diff --git a/Documentation/filesystems/xfs.txt b/Documentation/filesystems/xfs.txt
index 8146e9f..c2d44e6 100644
--- a/Documentation/filesystems/xfs.txt
+++ b/Documentation/filesystems/xfs.txt
@@ -348,3 +348,126 @@
   ----				-------
   fs.xfs.xfsbufd_centisec	v4.0
   fs.xfs.age_buffer_centisecs	v4.0
+
+
+Error handling
+==============
+
+XFS can act differently according to the type of error found during its
+operation. The implementation introduces the following concepts to the error
+handler:
+
+ -failure speed:
+	Defines how fast XFS should propagate an error upwards when a specific
+	error is found during the filesystem operation. It can propagate
+	immediately, after a defined number of retries, after a set time period,
+	or simply retry forever.
+
+ -error classes:
+	Specifies the subsystem the error configuration will apply to, such as
+	metadata IO or memory allocation. Different subsystems will have
+	different error handlers for which behaviour can be configured.
+
+ -error handlers:
+	Defines the behavior for a specific error.
+
+The filesystem behavior during an error can be set via sysfs files. Each
+error handler works independently - the first condition met by an error handler
+for a specific class will cause the error to be propagated rather than reset and
+retried.
+
+The action taken by the filesystem when the error is propagated is context
+dependent - it may cause a shut down in the case of an unrecoverable error,
+it may be reported back to userspace, or it may even be ignored because
+there's nothing useful we can with the error or anyone we can report it to (e.g.
+during unmount).
+
+The configuration files are organized into the following hierarchy for each
+mounted filesystem:
+
+  /sys/fs/xfs/<dev>/error/<class>/<error>/
+
+Where:
+  <dev>
+	The short device name of the mounted filesystem. This is the same device
+	name that shows up in XFS kernel error messages as "XFS(<dev>): ..."
+
+  <class>
+	The subsystem the error configuration belongs to. As of 4.9, the defined
+	classes are:
+
+		- "metadata": applies metadata buffer write IO
+
+  <error>
+	The individual error handler configurations.
+
+
+Each filesystem has "global" error configuration options defined in their top
+level directory:
+
+  /sys/fs/xfs/<dev>/error/
+
+  fail_at_unmount		(Min:  0  Default:  1  Max: 1)
+	Defines the filesystem error behavior at unmount time.
+
+	If set to a value of 1, XFS will override all other error configurations
+	during unmount and replace them with "immediate fail" characteristics.
+	i.e. no retries, no retry timeout. This will always allow unmount to
+	succeed when there are persistent errors present.
+
+	If set to 0, the configured retry behaviour will continue until all
+	retries and/or timeouts have been exhausted. This will delay unmount
+	completion when there are persistent errors, and it may prevent the
+	filesystem from ever unmounting fully in the case of "retry forever"
+	handler configurations.
+
+	Note: there is no guarantee that fail_at_unmount can be set whilst an
+	unmount is in progress. It is possible that the sysfs entries are
+	removed by the unmounting filesystem before a "retry forever" error
+	handler configuration causes unmount to hang, and hence the filesystem
+	must be configured appropriately before unmount begins to prevent
+	unmount hangs.
+
+Each filesystem has specific error class handlers that define the error
+propagation behaviour for specific errors. There is also a "default" error
+handler defined, which defines the behaviour for all errors that don't have
+specific handlers defined. Where multiple retry constraints are configuredi for
+a single error, the first retry configuration that expires will cause the error
+to be propagated. The handler configurations are found in the directory:
+
+  /sys/fs/xfs/<dev>/error/<class>/<error>/
+
+  max_retries			(Min: -1  Default: Varies  Max: INTMAX)
+	Defines the allowed number of retries of a specific error before
+	the filesystem will propagate the error. The retry count for a given
+	error context (e.g. a specific metadata buffer) is reset every time
+	there is a successful completion of the operation.
+
+	Setting the value to "-1" will cause XFS to retry forever for this
+	specific error.
+
+	Setting the value to "0" will cause XFS to fail immediately when the
+	specific error is reported.
+
+	Setting the value to "N" (where 0 < N < Max) will make XFS retry the
+	operation "N" times before propagating the error.
+
+  retry_timeout_seconds		(Min:  -1  Default:  Varies  Max: 1 day)
+	Define the amount of time (in seconds) that the filesystem is
+	allowed to retry its operations when the specific error is
+	found.
+
+	Setting the value to "-1" will allow XFS to retry forever for this
+	specific error.
+
+	Setting the value to "0" will cause XFS to fail immediately when the
+	specific error is reported.
+
+	Setting the value to "N" (where 0 < N < Max) will allow XFS to retry the
+	operation for up to "N" seconds before propagating the error.
+
+Note: The default behaviour for a specific error handler is dependent on both
+the class and error context. For example, the default values for
+"metadata/ENODEV" are "0" rather than "-1" so that this error handler defaults
+to "fail immediately" behaviour. This is done because ENODEV is a fatal,
+unrecoverable error no matter how many times the metadata IO is retried.
diff --git a/MAINTAINERS b/MAINTAINERS
index a306795..3246c85 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -12915,11 +12915,10 @@
 F:	drivers/xen/*swiotlb*
 
 XFS FILESYSTEM
-P:	Silicon Graphics Inc
 M:	Dave Chinner <david@fromorbit.com>
-M:	xfs@oss.sgi.com
-L:	xfs@oss.sgi.com
-W:	http://oss.sgi.com/projects/xfs
+M:	linux-xfs@vger.kernel.org
+L:	linux-xfs@vger.kernel.org
+W:	http://xfs.org/
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/dgc/linux-xfs.git
 S:	Supported
 F:	Documentation/filesystems/xfs.txt
diff --git a/fs/dax.c b/fs/dax.c
index 993dc6f..cc025f8 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -31,6 +31,8 @@
 #include <linux/vmstat.h>
 #include <linux/pfn_t.h>
 #include <linux/sizes.h>
+#include <linux/iomap.h>
+#include "internal.h"
 
 /*
  * We use lowest available bit in exceptional entry for locking, other two
@@ -580,14 +582,13 @@
 	return VM_FAULT_LOCKED;
 }
 
-static int copy_user_bh(struct page *to, struct inode *inode,
-		struct buffer_head *bh, unsigned long vaddr)
+static int copy_user_dax(struct block_device *bdev, sector_t sector, size_t size,
+		struct page *to, unsigned long vaddr)
 {
 	struct blk_dax_ctl dax = {
-		.sector = to_sector(bh, inode),
-		.size = bh->b_size,
+		.sector = sector,
+		.size = size,
 	};
-	struct block_device *bdev = bh->b_bdev;
 	void *vto;
 
 	if (dax_map_atomic(bdev, &dax) < 0)
@@ -790,14 +791,13 @@
 EXPORT_SYMBOL_GPL(dax_writeback_mapping_range);
 
 static int dax_insert_mapping(struct address_space *mapping,
-			struct buffer_head *bh, void **entryp,
-			struct vm_area_struct *vma, struct vm_fault *vmf)
+		struct block_device *bdev, sector_t sector, size_t size,
+		void **entryp, struct vm_area_struct *vma, struct vm_fault *vmf)
 {
 	unsigned long vaddr = (unsigned long)vmf->virtual_address;
-	struct block_device *bdev = bh->b_bdev;
 	struct blk_dax_ctl dax = {
-		.sector = to_sector(bh, mapping->host),
-		.size = bh->b_size,
+		.sector = sector,
+		.size = size,
 	};
 	void *ret;
 	void *entry = *entryp;
@@ -868,7 +868,8 @@
 	if (vmf->cow_page) {
 		struct page *new_page = vmf->cow_page;
 		if (buffer_written(&bh))
-			error = copy_user_bh(new_page, inode, &bh, vaddr);
+			error = copy_user_dax(bh.b_bdev, to_sector(&bh, inode),
+					bh.b_size, new_page, vaddr);
 		else
 			clear_user_highpage(new_page, vaddr);
 		if (error)
@@ -898,7 +899,8 @@
 
 	/* Filesystem should not return unwritten buffers to us! */
 	WARN_ON_ONCE(buffer_unwritten(&bh) || buffer_new(&bh));
-	error = dax_insert_mapping(mapping, &bh, &entry, vma, vmf);
+	error = dax_insert_mapping(mapping, bh.b_bdev, to_sector(&bh, inode),
+			bh.b_size, &entry, vma, vmf);
  unlock_entry:
 	put_locked_mapping_entry(mapping, vmf->pgoff, entry);
  out:
@@ -1241,3 +1243,229 @@
 	return dax_zero_page_range(inode, from, length, get_block);
 }
 EXPORT_SYMBOL_GPL(dax_truncate_page);
+
+#ifdef CONFIG_FS_IOMAP
+static loff_t
+iomap_dax_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
+		struct iomap *iomap)
+{
+	struct iov_iter *iter = data;
+	loff_t end = pos + length, done = 0;
+	ssize_t ret = 0;
+
+	if (iov_iter_rw(iter) == READ) {
+		end = min(end, i_size_read(inode));
+		if (pos >= end)
+			return 0;
+
+		if (iomap->type == IOMAP_HOLE || iomap->type == IOMAP_UNWRITTEN)
+			return iov_iter_zero(min(length, end - pos), iter);
+	}
+
+	if (WARN_ON_ONCE(iomap->type != IOMAP_MAPPED))
+		return -EIO;
+
+	while (pos < end) {
+		unsigned offset = pos & (PAGE_SIZE - 1);
+		struct blk_dax_ctl dax = { 0 };
+		ssize_t map_len;
+
+		dax.sector = iomap->blkno +
+			(((pos & PAGE_MASK) - iomap->offset) >> 9);
+		dax.size = (length + offset + PAGE_SIZE - 1) & PAGE_MASK;
+		map_len = dax_map_atomic(iomap->bdev, &dax);
+		if (map_len < 0) {
+			ret = map_len;
+			break;
+		}
+
+		dax.addr += offset;
+		map_len -= offset;
+		if (map_len > end - pos)
+			map_len = end - pos;
+
+		if (iov_iter_rw(iter) == WRITE)
+			map_len = copy_from_iter_pmem(dax.addr, map_len, iter);
+		else
+			map_len = copy_to_iter(dax.addr, map_len, iter);
+		dax_unmap_atomic(iomap->bdev, &dax);
+		if (map_len <= 0) {
+			ret = map_len ? map_len : -EFAULT;
+			break;
+		}
+
+		pos += map_len;
+		length -= map_len;
+		done += map_len;
+	}
+
+	return done ? done : ret;
+}
+
+/**
+ * iomap_dax_rw - Perform I/O to a DAX file
+ * @iocb:	The control block for this I/O
+ * @iter:	The addresses to do I/O from or to
+ * @ops:	iomap ops passed from the file system
+ *
+ * This function performs read and write operations to directly mapped
+ * persistent memory.  The callers needs to take care of read/write exclusion
+ * and evicting any page cache pages in the region under I/O.
+ */
+ssize_t
+iomap_dax_rw(struct kiocb *iocb, struct iov_iter *iter,
+		struct iomap_ops *ops)
+{
+	struct address_space *mapping = iocb->ki_filp->f_mapping;
+	struct inode *inode = mapping->host;
+	loff_t pos = iocb->ki_pos, ret = 0, done = 0;
+	unsigned flags = 0;
+
+	if (iov_iter_rw(iter) == WRITE)
+		flags |= IOMAP_WRITE;
+
+	/*
+	 * Yes, even DAX files can have page cache attached to them:  A zeroed
+	 * page is inserted into the pagecache when we have to serve a write
+	 * fault on a hole.  It should never be dirtied and can simply be
+	 * dropped from the pagecache once we get real data for the page.
+	 *
+	 * XXX: This is racy against mmap, and there's nothing we can do about
+	 * it. We'll eventually need to shift this down even further so that
+	 * we can check if we allocated blocks over a hole first.
+	 */
+	if (mapping->nrpages) {
+		ret = invalidate_inode_pages2_range(mapping,
+				pos >> PAGE_SHIFT,
+				(pos + iov_iter_count(iter) - 1) >> PAGE_SHIFT);
+		WARN_ON_ONCE(ret);
+	}
+
+	while (iov_iter_count(iter)) {
+		ret = iomap_apply(inode, pos, iov_iter_count(iter), flags, ops,
+				iter, iomap_dax_actor);
+		if (ret <= 0)
+			break;
+		pos += ret;
+		done += ret;
+	}
+
+	iocb->ki_pos += done;
+	return done ? done : ret;
+}
+EXPORT_SYMBOL_GPL(iomap_dax_rw);
+
+/**
+ * iomap_dax_fault - handle a page fault on a DAX file
+ * @vma: The virtual memory area where the fault occurred
+ * @vmf: The description of the fault
+ * @ops: iomap ops passed from the file system
+ *
+ * When a page fault occurs, filesystems may call this helper in their fault
+ * or mkwrite handler for DAX files. Assumes the caller has done all the
+ * necessary locking for the page fault to proceed successfully.
+ */
+int iomap_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
+			struct iomap_ops *ops)
+{
+	struct address_space *mapping = vma->vm_file->f_mapping;
+	struct inode *inode = mapping->host;
+	unsigned long vaddr = (unsigned long)vmf->virtual_address;
+	loff_t pos = (loff_t)vmf->pgoff << PAGE_SHIFT;
+	sector_t sector;
+	struct iomap iomap = { 0 };
+	unsigned flags = 0;
+	int error, major = 0;
+	void *entry;
+
+	/*
+	 * Check whether offset isn't beyond end of file now. Caller is supposed
+	 * to hold locks serializing us with truncate / punch hole so this is
+	 * a reliable test.
+	 */
+	if (pos >= i_size_read(inode))
+		return VM_FAULT_SIGBUS;
+
+	entry = grab_mapping_entry(mapping, vmf->pgoff);
+	if (IS_ERR(entry)) {
+		error = PTR_ERR(entry);
+		goto out;
+	}
+
+	if ((vmf->flags & FAULT_FLAG_WRITE) && !vmf->cow_page)
+		flags |= IOMAP_WRITE;
+
+	/*
+	 * Note that we don't bother to use iomap_apply here: DAX required
+	 * the file system block size to be equal the page size, which means
+	 * that we never have to deal with more than a single extent here.
+	 */
+	error = ops->iomap_begin(inode, pos, PAGE_SIZE, flags, &iomap);
+	if (error)
+		goto unlock_entry;
+	if (WARN_ON_ONCE(iomap.offset + iomap.length < pos + PAGE_SIZE)) {
+		error = -EIO;		/* fs corruption? */
+		goto unlock_entry;
+	}
+
+	sector = iomap.blkno + (((pos & PAGE_MASK) - iomap.offset) >> 9);
+
+	if (vmf->cow_page) {
+		switch (iomap.type) {
+		case IOMAP_HOLE:
+		case IOMAP_UNWRITTEN:
+			clear_user_highpage(vmf->cow_page, vaddr);
+			break;
+		case IOMAP_MAPPED:
+			error = copy_user_dax(iomap.bdev, sector, PAGE_SIZE,
+					vmf->cow_page, vaddr);
+			break;
+		default:
+			WARN_ON_ONCE(1);
+			error = -EIO;
+			break;
+		}
+
+		if (error)
+			goto unlock_entry;
+		if (!radix_tree_exceptional_entry(entry)) {
+			vmf->page = entry;
+			return VM_FAULT_LOCKED;
+		}
+		vmf->entry = entry;
+		return VM_FAULT_DAX_LOCKED;
+	}
+
+	switch (iomap.type) {
+	case IOMAP_MAPPED:
+		if (iomap.flags & IOMAP_F_NEW) {
+			count_vm_event(PGMAJFAULT);
+			mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT);
+			major = VM_FAULT_MAJOR;
+		}
+		error = dax_insert_mapping(mapping, iomap.bdev, sector,
+				PAGE_SIZE, &entry, vma, vmf);
+		break;
+	case IOMAP_UNWRITTEN:
+	case IOMAP_HOLE:
+		if (!(vmf->flags & FAULT_FLAG_WRITE))
+			return dax_load_hole(mapping, entry, vmf);
+		/*FALLTHRU*/
+	default:
+		WARN_ON_ONCE(1);
+		error = -EIO;
+		break;
+	}
+
+ unlock_entry:
+	put_locked_mapping_entry(mapping, vmf->pgoff, entry);
+ out:
+	if (error == -ENOMEM)
+		return VM_FAULT_OOM | major;
+	/* -EBUSY is fine, somebody else faulted on the same PTE */
+	if (error < 0 && error != -EBUSY)
+		return VM_FAULT_SIGBUS | major;
+	return VM_FAULT_NOPAGE | major;
+}
+EXPORT_SYMBOL_GPL(iomap_dax_fault);
+#endif /* CONFIG_FS_IOMAP */
diff --git a/fs/ext2/Kconfig b/fs/ext2/Kconfig
index c634874e..36bea5a 100644
--- a/fs/ext2/Kconfig
+++ b/fs/ext2/Kconfig
@@ -1,5 +1,6 @@
 config EXT2_FS
 	tristate "Second extended fs support"
+	select FS_IOMAP if FS_DAX
 	help
 	  Ext2 is a standard Linux file system for hard disks.
 
diff --git a/fs/ext2/ext2.h b/fs/ext2/ext2.h
index 06af2f9..37e2be7 100644
--- a/fs/ext2/ext2.h
+++ b/fs/ext2/ext2.h
@@ -814,6 +814,7 @@
 /* inode.c */
 extern const struct address_space_operations ext2_aops;
 extern const struct address_space_operations ext2_nobh_aops;
+extern struct iomap_ops ext2_iomap_ops;
 
 /* namei.c */
 extern const struct inode_operations ext2_dir_inode_operations;
diff --git a/fs/ext2/file.c b/fs/ext2/file.c
index 5efeefe..423cc01 100644
--- a/fs/ext2/file.c
+++ b/fs/ext2/file.c
@@ -22,11 +22,59 @@
 #include <linux/pagemap.h>
 #include <linux/dax.h>
 #include <linux/quotaops.h>
+#include <linux/iomap.h>
+#include <linux/uio.h>
 #include "ext2.h"
 #include "xattr.h"
 #include "acl.h"
 
 #ifdef CONFIG_FS_DAX
+static ssize_t ext2_dax_read_iter(struct kiocb *iocb, struct iov_iter *to)
+{
+	struct inode *inode = iocb->ki_filp->f_mapping->host;
+	ssize_t ret;
+
+	if (!iov_iter_count(to))
+		return 0; /* skip atime */
+
+	inode_lock_shared(inode);
+	ret = iomap_dax_rw(iocb, to, &ext2_iomap_ops);
+	inode_unlock_shared(inode);
+
+	file_accessed(iocb->ki_filp);
+	return ret;
+}
+
+static ssize_t ext2_dax_write_iter(struct kiocb *iocb, struct iov_iter *from)
+{
+	struct file *file = iocb->ki_filp;
+	struct inode *inode = file->f_mapping->host;
+	ssize_t ret;
+
+	inode_lock(inode);
+	ret = generic_write_checks(iocb, from);
+	if (ret <= 0)
+		goto out_unlock;
+	ret = file_remove_privs(file);
+	if (ret)
+		goto out_unlock;
+	ret = file_update_time(file);
+	if (ret)
+		goto out_unlock;
+
+	ret = iomap_dax_rw(iocb, from, &ext2_iomap_ops);
+	if (ret > 0 && iocb->ki_pos > i_size_read(inode)) {
+		i_size_write(inode, iocb->ki_pos);
+		mark_inode_dirty(inode);
+	}
+
+out_unlock:
+	inode_unlock(inode);
+	if (ret > 0)
+		ret = generic_write_sync(iocb, ret);
+	return ret;
+}
+
 /*
  * The lock ordering for ext2 DAX fault paths is:
  *
@@ -51,7 +99,7 @@
 	}
 	down_read(&ei->dax_sem);
 
-	ret = dax_fault(vma, vmf, ext2_get_block);
+	ret = iomap_dax_fault(vma, vmf, &ext2_iomap_ops);
 
 	up_read(&ei->dax_sem);
 	if (vmf->flags & FAULT_FLAG_WRITE)
@@ -156,14 +204,28 @@
 	return ret;
 }
 
-/*
- * We have mostly NULL's here: the current defaults are ok for
- * the ext2 filesystem.
- */
+static ssize_t ext2_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
+{
+#ifdef CONFIG_FS_DAX
+	if (IS_DAX(iocb->ki_filp->f_mapping->host))
+		return ext2_dax_read_iter(iocb, to);
+#endif
+	return generic_file_read_iter(iocb, to);
+}
+
+static ssize_t ext2_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
+{
+#ifdef CONFIG_FS_DAX
+	if (IS_DAX(iocb->ki_filp->f_mapping->host))
+		return ext2_dax_write_iter(iocb, from);
+#endif
+	return generic_file_write_iter(iocb, from);
+}
+
 const struct file_operations ext2_file_operations = {
 	.llseek		= generic_file_llseek,
-	.read_iter	= generic_file_read_iter,
-	.write_iter	= generic_file_write_iter,
+	.read_iter	= ext2_file_read_iter,
+	.write_iter	= ext2_file_write_iter,
 	.unlocked_ioctl = ext2_ioctl,
 #ifdef CONFIG_COMPAT
 	.compat_ioctl	= ext2_compat_ioctl,
diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c
index d5c7d09..c7dbb46 100644
--- a/fs/ext2/inode.c
+++ b/fs/ext2/inode.c
@@ -32,6 +32,7 @@
 #include <linux/buffer_head.h>
 #include <linux/mpage.h>
 #include <linux/fiemap.h>
+#include <linux/iomap.h>
 #include <linux/namei.h>
 #include <linux/uio.h>
 #include "ext2.h"
@@ -618,7 +619,7 @@
  */
 static int ext2_get_blocks(struct inode *inode,
 			   sector_t iblock, unsigned long maxblocks,
-			   struct buffer_head *bh_result,
+			   u32 *bno, bool *new, bool *boundary,
 			   int create)
 {
 	int err = -EIO;
@@ -644,7 +645,6 @@
 	/* Simplest case - block found, no allocation needed */
 	if (!partial) {
 		first_block = le32_to_cpu(chain[depth - 1].key);
-		clear_buffer_new(bh_result); /* What's this do? */
 		count++;
 		/*map more blocks*/
 		while (count < maxblocks && count <= blocks_to_boundary) {
@@ -699,7 +699,6 @@
 			mutex_unlock(&ei->truncate_mutex);
 			if (err)
 				goto cleanup;
-			clear_buffer_new(bh_result);
 			goto got_it;
 		}
 	}
@@ -745,15 +744,16 @@
 			mutex_unlock(&ei->truncate_mutex);
 			goto cleanup;
 		}
-	} else
-		set_buffer_new(bh_result);
+	} else {
+		*new = true;
+	}
 
 	ext2_splice_branch(inode, iblock, partial, indirect_blks, count);
 	mutex_unlock(&ei->truncate_mutex);
 got_it:
-	map_bh(bh_result, inode->i_sb, le32_to_cpu(chain[depth-1].key));
+	*bno = le32_to_cpu(chain[depth-1].key);
 	if (count > blocks_to_boundary)
-		set_buffer_boundary(bh_result);
+		*boundary = true;
 	err = count;
 	/* Clean up and exit */
 	partial = chain + depth - 1;	/* the whole chain */
@@ -765,19 +765,82 @@
 	return err;
 }
 
-int ext2_get_block(struct inode *inode, sector_t iblock, struct buffer_head *bh_result, int create)
+int ext2_get_block(struct inode *inode, sector_t iblock,
+		struct buffer_head *bh_result, int create)
 {
 	unsigned max_blocks = bh_result->b_size >> inode->i_blkbits;
-	int ret = ext2_get_blocks(inode, iblock, max_blocks,
-			      bh_result, create);
-	if (ret > 0) {
-		bh_result->b_size = (ret << inode->i_blkbits);
-		ret = 0;
-	}
-	return ret;
+	bool new = false, boundary = false;
+	u32 bno;
+	int ret;
+
+	ret = ext2_get_blocks(inode, iblock, max_blocks, &bno, &new, &boundary,
+			create);
+	if (ret <= 0)
+		return ret;
+
+	map_bh(bh_result, inode->i_sb, bno);
+	bh_result->b_size = (ret << inode->i_blkbits);
+	if (new)
+		set_buffer_new(bh_result);
+	if (boundary)
+		set_buffer_boundary(bh_result);
+	return 0;
 
 }
 
+#ifdef CONFIG_FS_DAX
+static int ext2_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
+		unsigned flags, struct iomap *iomap)
+{
+	unsigned int blkbits = inode->i_blkbits;
+	unsigned long first_block = offset >> blkbits;
+	unsigned long max_blocks = (length + (1 << blkbits) - 1) >> blkbits;
+	bool new = false, boundary = false;
+	u32 bno;
+	int ret;
+
+	ret = ext2_get_blocks(inode, first_block, max_blocks,
+			&bno, &new, &boundary, flags & IOMAP_WRITE);
+	if (ret < 0)
+		return ret;
+
+	iomap->flags = 0;
+	iomap->bdev = inode->i_sb->s_bdev;
+	iomap->offset = (u64)first_block << blkbits;
+
+	if (ret == 0) {
+		iomap->type = IOMAP_HOLE;
+		iomap->blkno = IOMAP_NULL_BLOCK;
+		iomap->length = 1 << blkbits;
+	} else {
+		iomap->type = IOMAP_MAPPED;
+		iomap->blkno = (sector_t)bno << (blkbits - 9);
+		iomap->length = (u64)ret << blkbits;
+		iomap->flags |= IOMAP_F_MERGED;
+	}
+
+	if (new)
+		iomap->flags |= IOMAP_F_NEW;
+	return 0;
+}
+
+static int
+ext2_iomap_end(struct inode *inode, loff_t offset, loff_t length,
+		ssize_t written, unsigned flags, struct iomap *iomap)
+{
+	if (iomap->type == IOMAP_MAPPED &&
+	    written < length &&
+	    (flags & IOMAP_WRITE))
+		ext2_write_failed(inode->i_mapping, offset + length);
+	return 0;
+}
+
+struct iomap_ops ext2_iomap_ops = {
+	.iomap_begin		= ext2_iomap_begin,
+	.iomap_end		= ext2_iomap_end,
+};
+#endif /* CONFIG_FS_DAX */
+
 int ext2_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 		u64 start, u64 len)
 {
@@ -863,11 +926,10 @@
 	loff_t offset = iocb->ki_pos;
 	ssize_t ret;
 
-	if (IS_DAX(inode))
-		ret = dax_do_io(iocb, inode, iter, ext2_get_block, NULL,
-				DIO_LOCKING);
-	else
-		ret = blockdev_direct_IO(iocb, inode, iter, ext2_get_block);
+	if (WARN_ON_ONCE(IS_DAX(inode)))
+		return -EIO;
+
+	ret = blockdev_direct_IO(iocb, inode, iter, ext2_get_block);
 	if (ret < 0 && iov_iter_rw(iter) == WRITE)
 		ext2_write_failed(mapping, offset + count);
 	return ret;
diff --git a/fs/internal.h b/fs/internal.h
index ba07376..8591786 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -12,6 +12,7 @@
 struct super_block;
 struct file_system_type;
 struct iomap;
+struct iomap_ops;
 struct linux_binprm;
 struct path;
 struct mount;
@@ -164,3 +165,13 @@
 extern int do_vfs_ioctl(struct file *file, unsigned int fd, unsigned int cmd,
 		    unsigned long arg);
 extern long vfs_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
+
+/*
+ * iomap support:
+ */
+typedef loff_t (*iomap_actor_t)(struct inode *inode, loff_t pos, loff_t len,
+		void *data, struct iomap *iomap);
+
+loff_t iomap_apply(struct inode *inode, loff_t pos, loff_t length,
+		unsigned flags, struct iomap_ops *ops, void *data,
+		iomap_actor_t actor);
diff --git a/fs/iomap.c b/fs/iomap.c
index 706270f..013d1d36 100644
--- a/fs/iomap.c
+++ b/fs/iomap.c
@@ -27,9 +27,6 @@
 #include <linux/dax.h>
 #include "internal.h"
 
-typedef loff_t (*iomap_actor_t)(struct inode *inode, loff_t pos, loff_t len,
-		void *data, struct iomap *iomap);
-
 /*
  * Execute a iomap write on a segment of the mapping that spans a
  * contiguous range of pages that have identical block mapping state.
@@ -41,7 +38,7 @@
  * resources they require in the iomap_begin call, and release them in the
  * iomap_end call.
  */
-static loff_t
+loff_t
 iomap_apply(struct inode *inode, loff_t pos, loff_t length, unsigned flags,
 		struct iomap_ops *ops, void *data, iomap_actor_t actor)
 {
@@ -252,6 +249,88 @@
 }
 EXPORT_SYMBOL_GPL(iomap_file_buffered_write);
 
+static struct page *
+__iomap_read_page(struct inode *inode, loff_t offset)
+{
+	struct address_space *mapping = inode->i_mapping;
+	struct page *page;
+
+	page = read_mapping_page(mapping, offset >> PAGE_SHIFT, NULL);
+	if (IS_ERR(page))
+		return page;
+	if (!PageUptodate(page)) {
+		put_page(page);
+		return ERR_PTR(-EIO);
+	}
+	return page;
+}
+
+static loff_t
+iomap_dirty_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
+		struct iomap *iomap)
+{
+	long status = 0;
+	ssize_t written = 0;
+
+	do {
+		struct page *page, *rpage;
+		unsigned long offset;	/* Offset into pagecache page */
+		unsigned long bytes;	/* Bytes to write to page */
+
+		offset = (pos & (PAGE_SIZE - 1));
+		bytes = min_t(unsigned long, PAGE_SIZE - offset, length);
+
+		rpage = __iomap_read_page(inode, pos);
+		if (IS_ERR(rpage))
+			return PTR_ERR(rpage);
+
+		status = iomap_write_begin(inode, pos, bytes,
+				AOP_FLAG_NOFS | AOP_FLAG_UNINTERRUPTIBLE,
+				&page, iomap);
+		put_page(rpage);
+		if (unlikely(status))
+			return status;
+
+		WARN_ON_ONCE(!PageUptodate(page));
+
+		status = iomap_write_end(inode, pos, bytes, bytes, page);
+		if (unlikely(status <= 0)) {
+			if (WARN_ON_ONCE(status == 0))
+				return -EIO;
+			return status;
+		}
+
+		cond_resched();
+
+		pos += status;
+		written += status;
+		length -= status;
+
+		balance_dirty_pages_ratelimited(inode->i_mapping);
+	} while (length);
+
+	return written;
+}
+
+int
+iomap_file_dirty(struct inode *inode, loff_t pos, loff_t len,
+		struct iomap_ops *ops)
+{
+	loff_t ret;
+
+	while (len) {
+		ret = iomap_apply(inode, pos, len, IOMAP_WRITE, ops, NULL,
+				iomap_dirty_actor);
+		if (ret <= 0)
+			return ret;
+		pos += ret;
+		len -= ret;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(iomap_file_dirty);
+
 static int iomap_zero(struct inode *inode, loff_t pos, unsigned offset,
 		unsigned bytes, struct iomap *iomap)
 {
@@ -430,6 +509,8 @@
 
 	if (iomap->flags & IOMAP_F_MERGED)
 		flags |= FIEMAP_EXTENT_MERGED;
+	if (iomap->flags & IOMAP_F_SHARED)
+		flags |= FIEMAP_EXTENT_SHARED;
 
 	return fiemap_fill_next_extent(fi, iomap->offset,
 			iomap->blkno != IOMAP_NULL_BLOCK ? iomap->blkno << 9: 0,
diff --git a/fs/xfs/Makefile b/fs/xfs/Makefile
index fc593c8..584e87e 100644
--- a/fs/xfs/Makefile
+++ b/fs/xfs/Makefile
@@ -52,6 +52,7 @@
 				   xfs_inode_fork.o \
 				   xfs_inode_buf.o \
 				   xfs_log_rlimit.o \
+				   xfs_ag_resv.o \
 				   xfs_rmap.o \
 				   xfs_rmap_btree.o \
 				   xfs_sb.o \
diff --git a/fs/xfs/libxfs/xfs_ag_resv.c b/fs/xfs/libxfs/xfs_ag_resv.c
new file mode 100644
index 0000000..e3ae0f2
--- /dev/null
+++ b/fs/xfs/libxfs/xfs_ag_resv.c
@@ -0,0 +1,325 @@
+/*
+ * Copyright (C) 2016 Oracle.  All Rights Reserved.
+ *
+ * Author: Darrick J. Wong <darrick.wong@oracle.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it would be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write the Free Software Foundation,
+ * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+#include "xfs.h"
+#include "xfs_fs.h"
+#include "xfs_shared.h"
+#include "xfs_format.h"
+#include "xfs_log_format.h"
+#include "xfs_trans_resv.h"
+#include "xfs_sb.h"
+#include "xfs_mount.h"
+#include "xfs_defer.h"
+#include "xfs_alloc.h"
+#include "xfs_error.h"
+#include "xfs_trace.h"
+#include "xfs_cksum.h"
+#include "xfs_trans.h"
+#include "xfs_bit.h"
+#include "xfs_bmap.h"
+#include "xfs_bmap_btree.h"
+#include "xfs_ag_resv.h"
+#include "xfs_trans_space.h"
+#include "xfs_rmap_btree.h"
+#include "xfs_btree.h"
+
+/*
+ * Per-AG Block Reservations
+ *
+ * For some kinds of allocation group metadata structures, it is advantageous
+ * to reserve a small number of blocks in each AG so that future expansions of
+ * that data structure do not encounter ENOSPC because errors during a btree
+ * split cause the filesystem to go offline.
+ *
+ * Prior to the introduction of reflink, this wasn't an issue because the free
+ * space btrees maintain a reserve of space (the AGFL) to handle any expansion
+ * that may be necessary; and allocations of other metadata (inodes, BMBT,
+ * dir/attr) aren't restricted to a single AG.  However, with reflink it is
+ * possible to allocate all the space in an AG, have subsequent reflink/CoW
+ * activity expand the refcount btree, and discover that there's no space left
+ * to handle that expansion.  Since we can calculate the maximum size of the
+ * refcount btree, we can reserve space for it and avoid ENOSPC.
+ *
+ * Handling per-AG reservations consists of three changes to the allocator's
+ * behavior:  First, because these reservations are always needed, we decrease
+ * the ag_max_usable counter to reflect the size of the AG after the reserved
+ * blocks are taken.  Second, the reservations must be reflected in the
+ * fdblocks count to maintain proper accounting.  Third, each AG must maintain
+ * its own reserved block counter so that we can calculate the amount of space
+ * that must remain free to maintain the reservations.  Fourth, the "remaining
+ * reserved blocks" count must be used when calculating the length of the
+ * longest free extent in an AG and to clamp maxlen in the per-AG allocation
+ * functions.  In other words, we maintain a virtual allocation via in-core
+ * accounting tricks so that we don't have to clean up after a crash. :)
+ *
+ * Reserved blocks can be managed by passing one of the enum xfs_ag_resv_type
+ * values via struct xfs_alloc_arg or directly to the xfs_free_extent
+ * function.  It might seem a little funny to maintain a reservoir of blocks
+ * to feed another reservoir, but the AGFL only holds enough blocks to get
+ * through the next transaction.  The per-AG reservation is to ensure (we
+ * hope) that each AG never runs out of blocks.  Each data structure wanting
+ * to use the reservation system should update ask/used in xfs_ag_resv_init.
+ */
+
+/*
+ * Are we critically low on blocks?  For now we'll define that as the number
+ * of blocks we can get our hands on being less than 10% of what we reserved
+ * or less than some arbitrary number (maximum btree height).
+ */
+bool
+xfs_ag_resv_critical(
+	struct xfs_perag		*pag,
+	enum xfs_ag_resv_type		type)
+{
+	xfs_extlen_t			avail;
+	xfs_extlen_t			orig;
+
+	switch (type) {
+	case XFS_AG_RESV_METADATA:
+		avail = pag->pagf_freeblks - pag->pag_agfl_resv.ar_reserved;
+		orig = pag->pag_meta_resv.ar_asked;
+		break;
+	case XFS_AG_RESV_AGFL:
+		avail = pag->pagf_freeblks + pag->pagf_flcount -
+			pag->pag_meta_resv.ar_reserved;
+		orig = pag->pag_agfl_resv.ar_asked;
+		break;
+	default:
+		ASSERT(0);
+		return false;
+	}
+
+	trace_xfs_ag_resv_critical(pag, type, avail);
+
+	/* Critically low if less than 10% or max btree height remains. */
+	return avail < orig / 10 || avail < XFS_BTREE_MAXLEVELS;
+}
+
+/*
+ * How many blocks are reserved but not used, and therefore must not be
+ * allocated away?
+ */
+xfs_extlen_t
+xfs_ag_resv_needed(
+	struct xfs_perag		*pag,
+	enum xfs_ag_resv_type		type)
+{
+	xfs_extlen_t			len;
+
+	len = pag->pag_meta_resv.ar_reserved + pag->pag_agfl_resv.ar_reserved;
+	switch (type) {
+	case XFS_AG_RESV_METADATA:
+	case XFS_AG_RESV_AGFL:
+		len -= xfs_perag_resv(pag, type)->ar_reserved;
+		break;
+	case XFS_AG_RESV_NONE:
+		/* empty */
+		break;
+	default:
+		ASSERT(0);
+	}
+
+	trace_xfs_ag_resv_needed(pag, type, len);
+
+	return len;
+}
+
+/* Clean out a reservation */
+static int
+__xfs_ag_resv_free(
+	struct xfs_perag		*pag,
+	enum xfs_ag_resv_type		type)
+{
+	struct xfs_ag_resv		*resv;
+	xfs_extlen_t			oldresv;
+	int				error;
+
+	trace_xfs_ag_resv_free(pag, type, 0);
+
+	resv = xfs_perag_resv(pag, type);
+	pag->pag_mount->m_ag_max_usable += resv->ar_asked;
+	/*
+	 * AGFL blocks are always considered "free", so whatever
+	 * was reserved at mount time must be given back at umount.
+	 */
+	if (type == XFS_AG_RESV_AGFL)
+		oldresv = resv->ar_orig_reserved;
+	else
+		oldresv = resv->ar_reserved;
+	error = xfs_mod_fdblocks(pag->pag_mount, oldresv, true);
+	resv->ar_reserved = 0;
+	resv->ar_asked = 0;
+
+	if (error)
+		trace_xfs_ag_resv_free_error(pag->pag_mount, pag->pag_agno,
+				error, _RET_IP_);
+	return error;
+}
+
+/* Free a per-AG reservation. */
+int
+xfs_ag_resv_free(
+	struct xfs_perag		*pag)
+{
+	int				error;
+	int				err2;
+
+	error = __xfs_ag_resv_free(pag, XFS_AG_RESV_AGFL);
+	err2 = __xfs_ag_resv_free(pag, XFS_AG_RESV_METADATA);
+	if (err2 && !error)
+		error = err2;
+	return error;
+}
+
+static int
+__xfs_ag_resv_init(
+	struct xfs_perag		*pag,
+	enum xfs_ag_resv_type		type,
+	xfs_extlen_t			ask,
+	xfs_extlen_t			used)
+{
+	struct xfs_mount		*mp = pag->pag_mount;
+	struct xfs_ag_resv		*resv;
+	int				error;
+
+	resv = xfs_perag_resv(pag, type);
+	if (used > ask)
+		ask = used;
+	resv->ar_asked = ask;
+	resv->ar_reserved = resv->ar_orig_reserved = ask - used;
+	mp->m_ag_max_usable -= ask;
+
+	trace_xfs_ag_resv_init(pag, type, ask);
+
+	error = xfs_mod_fdblocks(mp, -(int64_t)resv->ar_reserved, true);
+	if (error)
+		trace_xfs_ag_resv_init_error(pag->pag_mount, pag->pag_agno,
+				error, _RET_IP_);
+
+	return error;
+}
+
+/* Create a per-AG block reservation. */
+int
+xfs_ag_resv_init(
+	struct xfs_perag		*pag)
+{
+	xfs_extlen_t			ask;
+	xfs_extlen_t			used;
+	int				error = 0;
+
+	/* Create the metadata reservation. */
+	if (pag->pag_meta_resv.ar_asked == 0) {
+		ask = used = 0;
+
+		error = __xfs_ag_resv_init(pag, XFS_AG_RESV_METADATA,
+				ask, used);
+		if (error)
+			goto out;
+	}
+
+	/* Create the AGFL metadata reservation */
+	if (pag->pag_agfl_resv.ar_asked == 0) {
+		ask = used = 0;
+
+		error = __xfs_ag_resv_init(pag, XFS_AG_RESV_AGFL, ask, used);
+		if (error)
+			goto out;
+	}
+
+out:
+	return error;
+}
+
+/* Allocate a block from the reservation. */
+void
+xfs_ag_resv_alloc_extent(
+	struct xfs_perag		*pag,
+	enum xfs_ag_resv_type		type,
+	struct xfs_alloc_arg		*args)
+{
+	struct xfs_ag_resv		*resv;
+	xfs_extlen_t			len;
+	uint				field;
+
+	trace_xfs_ag_resv_alloc_extent(pag, type, args->len);
+
+	switch (type) {
+	case XFS_AG_RESV_METADATA:
+	case XFS_AG_RESV_AGFL:
+		resv = xfs_perag_resv(pag, type);
+		break;
+	default:
+		ASSERT(0);
+		/* fall through */
+	case XFS_AG_RESV_NONE:
+		field = args->wasdel ? XFS_TRANS_SB_RES_FDBLOCKS :
+				       XFS_TRANS_SB_FDBLOCKS;
+		xfs_trans_mod_sb(args->tp, field, -(int64_t)args->len);
+		return;
+	}
+
+	len = min_t(xfs_extlen_t, args->len, resv->ar_reserved);
+	resv->ar_reserved -= len;
+	if (type == XFS_AG_RESV_AGFL)
+		return;
+	/* Allocations of reserved blocks only need on-disk sb updates... */
+	xfs_trans_mod_sb(args->tp, XFS_TRANS_SB_RES_FDBLOCKS, -(int64_t)len);
+	/* ...but non-reserved blocks need in-core and on-disk updates. */
+	if (args->len > len)
+		xfs_trans_mod_sb(args->tp, XFS_TRANS_SB_FDBLOCKS,
+				-((int64_t)args->len - len));
+}
+
+/* Free a block to the reservation. */
+void
+xfs_ag_resv_free_extent(
+	struct xfs_perag		*pag,
+	enum xfs_ag_resv_type		type,
+	struct xfs_trans		*tp,
+	xfs_extlen_t			len)
+{
+	xfs_extlen_t			leftover;
+	struct xfs_ag_resv		*resv;
+
+	trace_xfs_ag_resv_free_extent(pag, type, len);
+
+	switch (type) {
+	case XFS_AG_RESV_METADATA:
+	case XFS_AG_RESV_AGFL:
+		resv = xfs_perag_resv(pag, type);
+		break;
+	default:
+		ASSERT(0);
+		/* fall through */
+	case XFS_AG_RESV_NONE:
+		xfs_trans_mod_sb(tp, XFS_TRANS_SB_FDBLOCKS, (int64_t)len);
+		return;
+	}
+
+	leftover = min_t(xfs_extlen_t, len, resv->ar_asked - resv->ar_reserved);
+	resv->ar_reserved += leftover;
+	if (type == XFS_AG_RESV_AGFL)
+		return;
+	/* Freeing into the reserved pool only requires on-disk update... */
+	xfs_trans_mod_sb(tp, XFS_TRANS_SB_RES_FDBLOCKS, len);
+	/* ...but freeing beyond that requires in-core and on-disk update. */
+	if (len > leftover)
+		xfs_trans_mod_sb(tp, XFS_TRANS_SB_FDBLOCKS, len - leftover);
+}
diff --git a/fs/xfs/libxfs/xfs_ag_resv.h b/fs/xfs/libxfs/xfs_ag_resv.h
new file mode 100644
index 0000000..8d6c687
--- /dev/null
+++ b/fs/xfs/libxfs/xfs_ag_resv.h
@@ -0,0 +1,35 @@
+/*
+ * Copyright (C) 2016 Oracle.  All Rights Reserved.
+ *
+ * Author: Darrick J. Wong <darrick.wong@oracle.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it would be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write the Free Software Foundation,
+ * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+#ifndef __XFS_AG_RESV_H__
+#define	__XFS_AG_RESV_H__
+
+int xfs_ag_resv_free(struct xfs_perag *pag);
+int xfs_ag_resv_init(struct xfs_perag *pag);
+
+bool xfs_ag_resv_critical(struct xfs_perag *pag, enum xfs_ag_resv_type type);
+xfs_extlen_t xfs_ag_resv_needed(struct xfs_perag *pag,
+		enum xfs_ag_resv_type type);
+
+void xfs_ag_resv_alloc_extent(struct xfs_perag *pag, enum xfs_ag_resv_type type,
+		struct xfs_alloc_arg *args);
+void xfs_ag_resv_free_extent(struct xfs_perag *pag, enum xfs_ag_resv_type type,
+		struct xfs_trans *tp, xfs_extlen_t len);
+
+#endif	/* __XFS_AG_RESV_H__ */
diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c
index 1d530c2..ca75dc9 100644
--- a/fs/xfs/libxfs/xfs_alloc.c
+++ b/fs/xfs/libxfs/xfs_alloc.c
@@ -37,6 +37,7 @@
 #include "xfs_trans.h"
 #include "xfs_buf_item.h"
 #include "xfs_log.h"
+#include "xfs_ag_resv.h"
 
 struct workqueue_struct *xfs_alloc_wq;
 
@@ -74,14 +75,8 @@
  * extents need to be actually allocated. To get around this, we explicitly set
  * aside a few blocks which will not be reserved in delayed allocation.
  *
- * When rmap is disabled, we need to reserve 4 fsbs _per AG_ for the freelist
- * and 4 more to handle a potential split of the file's bmap btree.
- *
- * When rmap is enabled, we must also be able to handle two rmap btree inserts
- * to record both the file data extent and a new bmbt block.  The bmbt block
- * might not be in the same AG as the file data extent.  In the worst case
- * the bmap btree splits multiple levels and all the new blocks come from
- * different AGs, so set aside enough to handle rmap btree splits in all AGs.
+ * We need to reserve 4 fsbs _per AG_ for the freelist and 4 more to handle a
+ * potential split of the file's bmap btree.
  */
 unsigned int
 xfs_alloc_set_aside(
@@ -90,8 +85,6 @@
 	unsigned int		blocks;
 
 	blocks = 4 + (mp->m_sb.sb_agcount * XFS_ALLOC_AGFL_RESERVE);
-	if (xfs_sb_version_hasrmapbt(&mp->m_sb))
-		blocks += mp->m_sb.sb_agcount * mp->m_rmap_maxlevels;
 	return blocks;
 }
 
@@ -681,12 +674,29 @@
 	xfs_alloc_arg_t	*args)	/* argument structure for allocation */
 {
 	int		error=0;
+	xfs_extlen_t	reservation;
+	xfs_extlen_t	oldmax;
 
 	ASSERT(args->minlen > 0);
 	ASSERT(args->maxlen > 0);
 	ASSERT(args->minlen <= args->maxlen);
 	ASSERT(args->mod < args->prod);
 	ASSERT(args->alignment > 0);
+
+	/*
+	 * Clamp maxlen to the amount of free space minus any reservations
+	 * that have been made.
+	 */
+	oldmax = args->maxlen;
+	reservation = xfs_ag_resv_needed(args->pag, args->resv);
+	if (args->maxlen > args->pag->pagf_freeblks - reservation)
+		args->maxlen = args->pag->pagf_freeblks - reservation;
+	if (args->maxlen == 0) {
+		args->agbno = NULLAGBLOCK;
+		args->maxlen = oldmax;
+		return 0;
+	}
+
 	/*
 	 * Branch to correct routine based on the type.
 	 */
@@ -706,12 +716,14 @@
 		/* NOTREACHED */
 	}
 
+	args->maxlen = oldmax;
+
 	if (error || args->agbno == NULLAGBLOCK)
 		return error;
 
 	ASSERT(args->len >= args->minlen);
 	ASSERT(args->len <= args->maxlen);
-	ASSERT(!args->wasfromfl || !args->isfl);
+	ASSERT(!args->wasfromfl || args->resv != XFS_AG_RESV_AGFL);
 	ASSERT(args->agbno % args->alignment == 0);
 
 	/* if not file data, insert new block into the reverse map btree */
@@ -733,12 +745,7 @@
 					      args->agbno, args->len));
 	}
 
-	if (!args->isfl) {
-		xfs_trans_mod_sb(args->tp, args->wasdel ?
-				 XFS_TRANS_SB_RES_FDBLOCKS :
-				 XFS_TRANS_SB_FDBLOCKS,
-				 -((long)(args->len)));
-	}
+	xfs_ag_resv_alloc_extent(args->pag, args->resv, args);
 
 	XFS_STATS_INC(args->mp, xs_allocx);
 	XFS_STATS_ADD(args->mp, xs_allocb, args->len);
@@ -1584,6 +1591,7 @@
 	int		*stat)	/* status: 0-freelist, 1-normal/none */
 {
 	struct xfs_owner_info	oinfo;
+	struct xfs_perag	*pag;
 	int		error;
 	xfs_agblock_t	fbno;
 	xfs_extlen_t	flen;
@@ -1601,7 +1609,8 @@
 	 * to respect minleft even when pulling from the
 	 * freelist.
 	 */
-	else if (args->minlen == 1 && args->alignment == 1 && !args->isfl &&
+	else if (args->minlen == 1 && args->alignment == 1 &&
+		 args->resv != XFS_AG_RESV_AGFL &&
 		 (be32_to_cpu(XFS_BUF_TO_AGF(args->agbp)->agf_flcount)
 		  > args->minleft)) {
 		error = xfs_alloc_get_freelist(args->tp, args->agbp, &fbno, 0);
@@ -1630,13 +1639,18 @@
 			/*
 			 * If we're feeding an AGFL block to something that
 			 * doesn't live in the free space, we need to clear
-			 * out the OWN_AG rmap.
+			 * out the OWN_AG rmap and add the block back to
+			 * the AGFL per-AG reservation.
 			 */
 			xfs_rmap_ag_owner(&oinfo, XFS_RMAP_OWN_AG);
 			error = xfs_rmap_free(args->tp, args->agbp, args->agno,
 					fbno, 1, &oinfo);
 			if (error)
 				goto error0;
+			pag = xfs_perag_get(args->mp, args->agno);
+			xfs_ag_resv_free_extent(pag, XFS_AG_RESV_AGFL,
+					args->tp, 1);
+			xfs_perag_put(pag);
 
 			*stat = 0;
 			return 0;
@@ -1684,7 +1698,7 @@
 	xfs_agblock_t		bno,
 	xfs_extlen_t		len,
 	struct xfs_owner_info	*oinfo,
-	int			isfl)
+	enum xfs_ag_resv_type	type)
 {
 	xfs_btree_cur_t	*bno_cur;	/* cursor for by-block btree */
 	xfs_btree_cur_t	*cnt_cur;	/* cursor for by-size btree */
@@ -1912,21 +1926,22 @@
 	 */
 	pag = xfs_perag_get(mp, agno);
 	error = xfs_alloc_update_counters(tp, pag, agbp, len);
+	xfs_ag_resv_free_extent(pag, type, tp, len);
 	xfs_perag_put(pag);
 	if (error)
 		goto error0;
 
-	if (!isfl)
-		xfs_trans_mod_sb(tp, XFS_TRANS_SB_FDBLOCKS, (long)len);
 	XFS_STATS_INC(mp, xs_freex);
 	XFS_STATS_ADD(mp, xs_freeb, len);
 
-	trace_xfs_free_extent(mp, agno, bno, len, isfl, haveleft, haveright);
+	trace_xfs_free_extent(mp, agno, bno, len, type == XFS_AG_RESV_AGFL,
+			haveleft, haveright);
 
 	return 0;
 
  error0:
-	trace_xfs_free_extent(mp, agno, bno, len, isfl, -1, -1);
+	trace_xfs_free_extent(mp, agno, bno, len, type == XFS_AG_RESV_AGFL,
+			-1, -1);
 	if (bno_cur)
 		xfs_btree_del_cursor(bno_cur, XFS_BTREE_ERROR);
 	if (cnt_cur)
@@ -1951,21 +1966,43 @@
 }
 
 /*
- * Find the length of the longest extent in an AG.
+ * Find the length of the longest extent in an AG.  The 'need' parameter
+ * specifies how much space we're going to need for the AGFL and the
+ * 'reserved' parameter tells us how many blocks in this AG are reserved for
+ * other callers.
  */
 xfs_extlen_t
 xfs_alloc_longest_free_extent(
 	struct xfs_mount	*mp,
 	struct xfs_perag	*pag,
-	xfs_extlen_t		need)
+	xfs_extlen_t		need,
+	xfs_extlen_t		reserved)
 {
 	xfs_extlen_t		delta = 0;
 
+	/*
+	 * If the AGFL needs a recharge, we'll have to subtract that from the
+	 * longest extent.
+	 */
 	if (need > pag->pagf_flcount)
 		delta = need - pag->pagf_flcount;
 
+	/*
+	 * If we cannot maintain others' reservations with space from the
+	 * not-longest freesp extents, we'll have to subtract /that/ from
+	 * the longest extent too.
+	 */
+	if (pag->pagf_freeblks - pag->pagf_longest < reserved)
+		delta += reserved - (pag->pagf_freeblks - pag->pagf_longest);
+
+	/*
+	 * If the longest extent is long enough to satisfy all the
+	 * reservations and AGFL rules in place, we can return this extent.
+	 */
 	if (pag->pagf_longest > delta)
 		return pag->pagf_longest - delta;
+
+	/* Otherwise, let the caller try for 1 block if there's space. */
 	return pag->pagf_flcount > 0 || pag->pagf_longest > 0;
 }
 
@@ -2005,20 +2042,24 @@
 {
 	struct xfs_perag	*pag = args->pag;
 	xfs_extlen_t		longest;
+	xfs_extlen_t		reservation; /* blocks that are still reserved */
 	int			available;
 
 	if (flags & XFS_ALLOC_FLAG_FREEING)
 		return true;
 
+	reservation = xfs_ag_resv_needed(pag, args->resv);
+
 	/* do we have enough contiguous free space for the allocation? */
-	longest = xfs_alloc_longest_free_extent(args->mp, pag, min_free);
+	longest = xfs_alloc_longest_free_extent(args->mp, pag, min_free,
+			reservation);
 	if ((args->minlen + args->alignment + args->minalignslop - 1) > longest)
 		return false;
 
-	/* do have enough free space remaining for the allocation? */
+	/* do we have enough free space remaining for the allocation? */
 	available = (int)(pag->pagf_freeblks + pag->pagf_flcount -
-			  min_free - args->total);
-	if (available < (int)args->minleft)
+			  reservation - min_free - args->total);
+	if (available < (int)args->minleft || available <= 0)
 		return false;
 
 	return true;
@@ -2125,7 +2166,7 @@
 		if (error)
 			goto out_agbp_relse;
 		error = xfs_free_ag_extent(tp, agbp, args->agno, bno, 1,
-					   &targs.oinfo, 1);
+					   &targs.oinfo, XFS_AG_RESV_AGFL);
 		if (error)
 			goto out_agbp_relse;
 		bp = xfs_btree_get_bufs(mp, tp, args->agno, bno, 0);
@@ -2136,7 +2177,7 @@
 	targs.mp = mp;
 	targs.agbp = agbp;
 	targs.agno = args->agno;
-	targs.alignment = targs.minlen = targs.prod = targs.isfl = 1;
+	targs.alignment = targs.minlen = targs.prod = 1;
 	targs.type = XFS_ALLOCTYPE_THIS_AG;
 	targs.pag = pag;
 	error = xfs_alloc_read_agfl(mp, tp, targs.agno, &agflbp);
@@ -2147,6 +2188,7 @@
 	while (pag->pagf_flcount < need) {
 		targs.agbno = 0;
 		targs.maxlen = need - pag->pagf_flcount;
+		targs.resv = XFS_AG_RESV_AGFL;
 
 		/* Allocate as many blocks as possible at once. */
 		error = xfs_alloc_ag_vextent(&targs);
@@ -2826,7 +2868,8 @@
 	struct xfs_trans	*tp,	/* transaction pointer */
 	xfs_fsblock_t		bno,	/* starting block number of extent */
 	xfs_extlen_t		len,	/* length of extent */
-	struct xfs_owner_info	*oinfo)	/* extent owner */
+	struct xfs_owner_info	*oinfo,	/* extent owner */
+	enum xfs_ag_resv_type	type)	/* block reservation type */
 {
 	struct xfs_mount	*mp = tp->t_mountp;
 	struct xfs_buf		*agbp;
@@ -2835,6 +2878,7 @@
 	int			error;
 
 	ASSERT(len != 0);
+	ASSERT(type != XFS_AG_RESV_AGFL);
 
 	if (XFS_TEST_ERROR(false, mp,
 			XFS_ERRTAG_FREE_EXTENT,
@@ -2852,7 +2896,7 @@
 		agbno + len <= be32_to_cpu(XFS_BUF_TO_AGF(agbp)->agf_length),
 				err);
 
-	error = xfs_free_ag_extent(tp, agbp, agno, agbno, len, oinfo, 0);
+	error = xfs_free_ag_extent(tp, agbp, agno, agbno, len, oinfo, type);
 	if (error)
 		goto err;
 
diff --git a/fs/xfs/libxfs/xfs_alloc.h b/fs/xfs/libxfs/xfs_alloc.h
index 7fd8eaf..7c404a6 100644
--- a/fs/xfs/libxfs/xfs_alloc.h
+++ b/fs/xfs/libxfs/xfs_alloc.h
@@ -88,9 +88,9 @@
 	int		datatype;	/* mask defining data type treatment */
 	char		wasdel;		/* set if allocation was prev delayed */
 	char		wasfromfl;	/* set if allocation is from freelist */
-	char		isfl;		/* set if is freelist blocks - !acctg */
 	xfs_fsblock_t	firstblock;	/* io first block allocated */
 	struct xfs_owner_info	oinfo;	/* owner of blocks being allocated */
+	enum xfs_ag_resv_type	resv;	/* block reservation to use */
 } xfs_alloc_arg_t;
 
 /*
@@ -119,7 +119,8 @@
 unsigned int xfs_alloc_ag_max_usable(struct xfs_mount *mp);
 
 xfs_extlen_t xfs_alloc_longest_free_extent(struct xfs_mount *mp,
-		struct xfs_perag *pag, xfs_extlen_t need);
+		struct xfs_perag *pag, xfs_extlen_t need,
+		xfs_extlen_t reserved);
 unsigned int xfs_alloc_min_freelist(struct xfs_mount *mp,
 		struct xfs_perag *pag);
 
@@ -197,7 +198,8 @@
 	struct xfs_trans	*tp,	/* transaction pointer */
 	xfs_fsblock_t		bno,	/* starting block number of extent */
 	xfs_extlen_t		len,	/* length of extent */
-	struct xfs_owner_info	*oinfo);/* extent owner */
+	struct xfs_owner_info	*oinfo,	/* extent owner */
+	enum xfs_ag_resv_type	type);	/* block reservation type */
 
 int				/* error */
 xfs_alloc_lookup_ge(
diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index 06d1201..9d7f61d 100644
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -47,6 +47,7 @@
 #include "xfs_attr_leaf.h"
 #include "xfs_filestream.h"
 #include "xfs_rmap.h"
+#include "xfs_ag_resv.h"
 
 
 kmem_zone_t		*xfs_bmap_free_item_zone;
@@ -1388,7 +1389,7 @@
  * Else, *lastxp will be set to the index of the found
  * entry; *gotp will contain the entry.
  */
-STATIC xfs_bmbt_rec_host_t *                 /* pointer to found extent entry */
+xfs_bmbt_rec_host_t *                 /* pointer to found extent entry */
 xfs_bmap_search_extents(
 	xfs_inode_t     *ip,            /* incore inode pointer */
 	xfs_fileoff_t   bno,            /* block number searched for */
@@ -3502,7 +3503,8 @@
 	}
 
 	longest = xfs_alloc_longest_free_extent(mp, pag,
-					xfs_alloc_min_freelist(mp, pag));
+				xfs_alloc_min_freelist(mp, pag),
+				xfs_ag_resv_needed(pag, XFS_AG_RESV_NONE));
 	if (*blen < longest)
 		*blen = longest;
 
@@ -3785,7 +3787,7 @@
 	}
 	args.minleft = ap->minleft;
 	args.wasdel = ap->wasdel;
-	args.isfl = 0;
+	args.resv = XFS_AG_RESV_NONE;
 	args.datatype = ap->datatype;
 	if (ap->datatype & XFS_ALLOC_USERDATA_ZERO)
 		args.ip = ap->ip;
@@ -4079,7 +4081,7 @@
 	return 0;
 }
 
-STATIC int
+int
 xfs_bmapi_reserve_delalloc(
 	struct xfs_inode	*ip,
 	xfs_fileoff_t		aoff,
@@ -4175,91 +4177,6 @@
 	return error;
 }
 
-/*
- * Map file blocks to filesystem blocks, adding delayed allocations as needed.
- */
-int
-xfs_bmapi_delay(
-	struct xfs_inode	*ip,	/* incore inode */
-	xfs_fileoff_t		bno,	/* starting file offs. mapped */
-	xfs_filblks_t		len,	/* length to map in file */
-	struct xfs_bmbt_irec	*mval,	/* output: map values */
-	int			*nmap,	/* i/o: mval size/count */
-	int			flags)	/* XFS_BMAPI_... */
-{
-	struct xfs_mount	*mp = ip->i_mount;
-	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, XFS_DATA_FORK);
-	struct xfs_bmbt_irec	got;	/* current file extent record */
-	struct xfs_bmbt_irec	prev;	/* previous file extent record */
-	xfs_fileoff_t		obno;	/* old block number (offset) */
-	xfs_fileoff_t		end;	/* end of mapped file region */
-	xfs_extnum_t		lastx;	/* last useful extent number */
-	int			eof;	/* we've hit the end of extents */
-	int			n = 0;	/* current extent index */
-	int			error = 0;
-
-	ASSERT(*nmap >= 1);
-	ASSERT(*nmap <= XFS_BMAP_MAX_NMAP);
-	ASSERT(!(flags & ~XFS_BMAPI_ENTIRE));
-	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
-
-	if (unlikely(XFS_TEST_ERROR(
-	    (XFS_IFORK_FORMAT(ip, XFS_DATA_FORK) != XFS_DINODE_FMT_EXTENTS &&
-	     XFS_IFORK_FORMAT(ip, XFS_DATA_FORK) != XFS_DINODE_FMT_BTREE),
-	     mp, XFS_ERRTAG_BMAPIFORMAT, XFS_RANDOM_BMAPIFORMAT))) {
-		XFS_ERROR_REPORT("xfs_bmapi_delay", XFS_ERRLEVEL_LOW, mp);
-		return -EFSCORRUPTED;
-	}
-
-	if (XFS_FORCED_SHUTDOWN(mp))
-		return -EIO;
-
-	XFS_STATS_INC(mp, xs_blk_mapw);
-
-	if (!(ifp->if_flags & XFS_IFEXTENTS)) {
-		error = xfs_iread_extents(NULL, ip, XFS_DATA_FORK);
-		if (error)
-			return error;
-	}
-
-	xfs_bmap_search_extents(ip, bno, XFS_DATA_FORK, &eof, &lastx, &got, &prev);
-	end = bno + len;
-	obno = bno;
-
-	while (bno < end && n < *nmap) {
-		if (eof || got.br_startoff > bno) {
-			error = xfs_bmapi_reserve_delalloc(ip, bno, len, &got,
-							   &prev, &lastx, eof);
-			if (error) {
-				if (n == 0) {
-					*nmap = 0;
-					return error;
-				}
-				break;
-			}
-		}
-
-		/* set up the extent map to return. */
-		xfs_bmapi_trim_map(mval, &got, &bno, len, obno, end, n, flags);
-		xfs_bmapi_update_map(&mval, &bno, &len, obno, end, &n, flags);
-
-		/* If we're done, stop now. */
-		if (bno >= end || n >= *nmap)
-			break;
-
-		/* Else go on to the next record. */
-		prev = got;
-		if (++lastx < ifp->if_bytes / sizeof(xfs_bmbt_rec_t))
-			xfs_bmbt_get_all(xfs_iext_get_ext(ifp, lastx), &got);
-		else
-			eof = 1;
-	}
-
-	*nmap = n;
-	return 0;
-}
-
-
 static int
 xfs_bmapi_allocate(
 	struct xfs_bmalloca	*bma)
diff --git a/fs/xfs/libxfs/xfs_bmap.h b/fs/xfs/libxfs/xfs_bmap.h
index 05576b7..8395f6e 100644
--- a/fs/xfs/libxfs/xfs_bmap.h
+++ b/fs/xfs/libxfs/xfs_bmap.h
@@ -181,9 +181,6 @@
 int	xfs_bmapi_read(struct xfs_inode *ip, xfs_fileoff_t bno,
 		xfs_filblks_t len, struct xfs_bmbt_irec *mval,
 		int *nmap, int flags);
-int	xfs_bmapi_delay(struct xfs_inode *ip, xfs_fileoff_t bno,
-		xfs_filblks_t len, struct xfs_bmbt_irec *mval,
-		int *nmap, int flags);
 int	xfs_bmapi_write(struct xfs_trans *tp, struct xfs_inode *ip,
 		xfs_fileoff_t bno, xfs_filblks_t len, int flags,
 		xfs_fsblock_t *firstblock, xfs_extlen_t total,
@@ -202,5 +199,12 @@
 		struct xfs_defer_ops *dfops, enum shift_direction direction,
 		int num_exts);
 int	xfs_bmap_split_extent(struct xfs_inode *ip, xfs_fileoff_t split_offset);
+struct xfs_bmbt_rec_host *
+	xfs_bmap_search_extents(struct xfs_inode *ip, xfs_fileoff_t bno,
+		int fork, int *eofp, xfs_extnum_t *lastxp,
+		struct xfs_bmbt_irec *gotp, struct xfs_bmbt_irec *prevp);
+int	xfs_bmapi_reserve_delalloc(struct xfs_inode *ip, xfs_fileoff_t aoff,
+		xfs_filblks_t len, struct xfs_bmbt_irec *got,
+		struct xfs_bmbt_irec *prev, xfs_extnum_t *lastx, int eof);
 
 #endif	/* __XFS_BMAP_H__ */
diff --git a/fs/xfs/libxfs/xfs_btree.c b/fs/xfs/libxfs/xfs_btree.c
index 0856979..aa1752f 100644
--- a/fs/xfs/libxfs/xfs_btree.c
+++ b/fs/xfs/libxfs/xfs_btree.c
@@ -2070,7 +2070,7 @@
 	struct xfs_buf		*bp0,
 	bool			force_all)
 {
-	union xfs_btree_bigkey	key;	/* keys from current level */
+	union xfs_btree_key	key;	/* keys from current level */
 	union xfs_btree_key	*lkey;	/* keys from the next level up */
 	union xfs_btree_key	*hkey;
 	union xfs_btree_key	*nlkey;	/* keys from the next level up */
@@ -2086,7 +2086,7 @@
 
 	trace_xfs_btree_updkeys(cur, level, bp0);
 
-	lkey = (union xfs_btree_key *)&key;
+	lkey = &key;
 	hkey = xfs_btree_high_key_from_key(cur, lkey);
 	xfs_btree_get_keys(cur, block, lkey);
 	for (level++; level < cur->bc_nlevels; level++) {
@@ -3226,7 +3226,7 @@
 	struct xfs_buf		*bp;	/* buffer for block */
 	union xfs_btree_ptr	nptr;	/* new block ptr */
 	struct xfs_btree_cur	*ncur;	/* new btree cursor */
-	union xfs_btree_bigkey	nkey;	/* new block key */
+	union xfs_btree_key	nkey;	/* new block key */
 	union xfs_btree_key	*lkey;
 	int			optr;	/* old key/record index */
 	int			ptr;	/* key/record index */
@@ -3241,7 +3241,7 @@
 	XFS_BTREE_TRACE_ARGIPR(cur, level, *ptrp, &rec);
 
 	ncur = NULL;
-	lkey = (union xfs_btree_key *)&nkey;
+	lkey = &nkey;
 
 	/*
 	 * If we have an external root pointer, and we've made it to the
@@ -3444,14 +3444,14 @@
 	union xfs_btree_ptr	nptr;	/* new block number (split result) */
 	struct xfs_btree_cur	*ncur;	/* new cursor (split result) */
 	struct xfs_btree_cur	*pcur;	/* previous level's cursor */
-	union xfs_btree_bigkey	bkey;	/* key of block to insert */
+	union xfs_btree_key	bkey;	/* key of block to insert */
 	union xfs_btree_key	*key;
 	union xfs_btree_rec	rec;	/* record to insert */
 
 	level = 0;
 	ncur = NULL;
 	pcur = cur;
-	key = (union xfs_btree_key *)&bkey;
+	key = &bkey;
 
 	xfs_btree_set_ptr_null(cur, &nptr);
 
@@ -4797,3 +4797,50 @@
 	return xfs_btree_overlapped_query_range(cur, &low_key, &high_key,
 			fn, priv);
 }
+
+/*
+ * Calculate the number of blocks needed to store a given number of records
+ * in a short-format (per-AG metadata) btree.
+ */
+xfs_extlen_t
+xfs_btree_calc_size(
+	struct xfs_mount	*mp,
+	uint			*limits,
+	unsigned long long	len)
+{
+	int			level;
+	int			maxrecs;
+	xfs_extlen_t		rval;
+
+	maxrecs = limits[0];
+	for (level = 0, rval = 0; len > 1; level++) {
+		len += maxrecs - 1;
+		do_div(len, maxrecs);
+		maxrecs = limits[1];
+		rval += len;
+	}
+	return rval;
+}
+
+int
+xfs_btree_count_blocks_helper(
+	struct xfs_btree_cur	*cur,
+	int			level,
+	void			*data)
+{
+	xfs_extlen_t		*blocks = data;
+	(*blocks)++;
+
+	return 0;
+}
+
+/* Count the blocks in a btree and return the result in *blocks. */
+int
+xfs_btree_count_blocks(
+	struct xfs_btree_cur	*cur,
+	xfs_extlen_t		*blocks)
+{
+	*blocks = 0;
+	return xfs_btree_visit_blocks(cur, xfs_btree_count_blocks_helper,
+			blocks);
+}
diff --git a/fs/xfs/libxfs/xfs_btree.h b/fs/xfs/libxfs/xfs_btree.h
index 04d0865..3f8556a 100644
--- a/fs/xfs/libxfs/xfs_btree.h
+++ b/fs/xfs/libxfs/xfs_btree.h
@@ -37,30 +37,18 @@
 	__be64			l;	/* long form ptr */
 };
 
+/*
+ * The in-core btree key.  Overlapping btrees actually store two keys
+ * per pointer, so we reserve enough memory to hold both.  The __*bigkey
+ * items should never be accessed directly.
+ */
 union xfs_btree_key {
 	struct xfs_bmbt_key		bmbt;
 	xfs_bmdr_key_t			bmbr;	/* bmbt root block */
 	xfs_alloc_key_t			alloc;
 	struct xfs_inobt_key		inobt;
 	struct xfs_rmap_key		rmap;
-};
-
-/*
- * In-core key that holds both low and high keys for overlapped btrees.
- * The two keys are packed next to each other on disk, so do the same
- * in memory.  Preserve the existing xfs_btree_key as a single key to
- * avoid the mental model breakage that would happen if we passed a
- * bigkey into a function that operates on a single key.
- */
-union xfs_btree_bigkey {
-	struct xfs_bmbt_key		bmbt;
-	xfs_bmdr_key_t			bmbr;	/* bmbt root block */
-	xfs_alloc_key_t			alloc;
-	struct xfs_inobt_key		inobt;
-	struct {
-		struct xfs_rmap_key	rmap;
-		struct xfs_rmap_key	rmap_hi;
-	};
+	struct xfs_rmap_key		__rmap_bigkey[2];
 };
 
 union xfs_btree_rec {
@@ -513,6 +501,8 @@
 bool xfs_btree_sblock_verify(struct xfs_buf *bp, unsigned int max_recs);
 uint xfs_btree_compute_maxlevels(struct xfs_mount *mp, uint *limits,
 				 unsigned long len);
+xfs_extlen_t xfs_btree_calc_size(struct xfs_mount *mp, uint *limits,
+		unsigned long long len);
 
 /* return codes */
 #define XFS_BTREE_QUERY_RANGE_CONTINUE	0	/* keep iterating */
@@ -529,4 +519,6 @@
 int xfs_btree_visit_blocks(struct xfs_btree_cur *cur,
 		xfs_btree_visit_blocks_fn fn, void *data);
 
+int xfs_btree_count_blocks(struct xfs_btree_cur *cur, xfs_extlen_t *blocks);
+
 #endif	/* __XFS_BTREE_H__ */
diff --git a/fs/xfs/libxfs/xfs_defer.c b/fs/xfs/libxfs/xfs_defer.c
index c221d0e..613c5cf1 100644
--- a/fs/xfs/libxfs/xfs_defer.c
+++ b/fs/xfs/libxfs/xfs_defer.c
@@ -81,6 +81,10 @@
  *   - For each work item attached to the log intent item,
  *     * Perform the described action.
  *     * Attach the work item to the log done item.
+ *     * If the result of doing the work was -EAGAIN, ->finish work
+ *       wants a new transaction.  See the "Requesting a Fresh
+ *       Transaction while Finishing Deferred Work" section below for
+ *       details.
  *
  * The key here is that we must log an intent item for all pending
  * work items every time we roll the transaction, and that we must log
@@ -88,6 +92,34 @@
  * we can perform complex remapping operations, chaining intent items
  * as needed.
  *
+ * Requesting a Fresh Transaction while Finishing Deferred Work
+ *
+ * If ->finish_item decides that it needs a fresh transaction to
+ * finish the work, it must ask its caller (xfs_defer_finish) for a
+ * continuation.  The most likely cause of this circumstance are the
+ * refcount adjust functions deciding that they've logged enough items
+ * to be at risk of exceeding the transaction reservation.
+ *
+ * To get a fresh transaction, we want to log the existing log done
+ * item to prevent the log intent item from replaying, immediately log
+ * a new log intent item with the unfinished work items, roll the
+ * transaction, and re-call ->finish_item wherever it left off.  The
+ * log done item and the new log intent item must be in the same
+ * transaction or atomicity cannot be guaranteed; defer_finish ensures
+ * that this happens.
+ *
+ * This requires some coordination between ->finish_item and
+ * defer_finish.  Upon deciding to request a new transaction,
+ * ->finish_item should update the current work item to reflect the
+ * unfinished work.  Next, it should reset the log done item's list
+ * count to the number of items finished, and return -EAGAIN.
+ * defer_finish sees the -EAGAIN, logs the new log intent item
+ * with the remaining work items, and leaves the xfs_defer_pending
+ * item at the head of the dop_work queue.  Then it rolls the
+ * transaction and picks up processing where it left off.  It is
+ * required that ->finish_item must be careful to leave enough
+ * transaction reservation to fit the new log intent item.
+ *
  * This is an example of remapping the extent (E, E+B) into file X at
  * offset A and dealing with the extent (C, C+B) already being mapped
  * there:
@@ -104,21 +136,26 @@
  * | Intent to add rmap (X, E, A, B)                 |
  * +-------------------------------------------------+
  * | Reduce refcount for extent (C, B)               | t2
- * | Done reducing refcount for extent (C, B)        |
+ * | Done reducing refcount for extent (C, 9)        |
+ * | Intent to reduce refcount for extent (C+9, B-9) |
+ * | (ran out of space after 9 refcount updates)     |
+ * +-------------------------------------------------+
+ * | Reduce refcount for extent (C+9, B+9)           | t3
+ * | Done reducing refcount for extent (C+9, B-9)    |
  * | Increase refcount for extent (E, B)             |
  * | Done increasing refcount for extent (E, B)      |
  * | Intent to free extent (C, B)                    |
  * | Intent to free extent (F, 1) (refcountbt block) |
  * | Intent to remove rmap (F, 1, REFC)              |
  * +-------------------------------------------------+
- * | Remove rmap (X, C, A, B)                        | t3
+ * | Remove rmap (X, C, A, B)                        | t4
  * | Done removing rmap (X, C, A, B)                 |
  * | Add rmap (X, E, A, B)                           |
  * | Done adding rmap (X, E, A, B)                   |
  * | Remove rmap (F, 1, REFC)                        |
  * | Done removing rmap (F, 1, REFC)                 |
  * +-------------------------------------------------+
- * | Free extent (C, B)                              | t4
+ * | Free extent (C, B)                              | t5
  * | Done freeing extent (C, B)                      |
  * | Free extent (D, 1)                              |
  * | Done freeing extent (D, 1)                      |
@@ -141,6 +178,9 @@
  * - Intent to free extent (C, B)
  * - Intent to free extent (F, 1) (refcountbt block)
  * - Intent to remove rmap (F, 1, REFC)
+ *
+ * Note that the continuation requested between t2 and t3 is likely to
+ * reoccur.
  */
 
 static const struct xfs_defer_op_type *defer_op_types[XFS_DEFER_OPS_TYPE_MAX];
@@ -323,7 +363,16 @@
 			dfp->dfp_count--;
 			error = dfp->dfp_type->finish_item(*tp, dop, li,
 					dfp->dfp_done, &state);
-			if (error) {
+			if (error == -EAGAIN) {
+				/*
+				 * Caller wants a fresh transaction;
+				 * put the work item back on the list
+				 * and jump out.
+				 */
+				list_add(li, &dfp->dfp_work);
+				dfp->dfp_count++;
+				break;
+			} else if (error) {
 				/*
 				 * Clean up after ourselves and jump out.
 				 * xfs_defer_cancel will take care of freeing
@@ -335,9 +384,25 @@
 				goto out;
 			}
 		}
-		/* Done with the dfp, free it. */
-		list_del(&dfp->dfp_list);
-		kmem_free(dfp);
+		if (error == -EAGAIN) {
+			/*
+			 * Caller wants a fresh transaction, so log a
+			 * new log intent item to replace the old one
+			 * and roll the transaction.  See "Requesting
+			 * a Fresh Transaction while Finishing
+			 * Deferred Work" above.
+			 */
+			dfp->dfp_intent = dfp->dfp_type->create_intent(*tp,
+					dfp->dfp_count);
+			dfp->dfp_done = NULL;
+			list_for_each(li, &dfp->dfp_work)
+				dfp->dfp_type->log_item(*tp, dfp->dfp_intent,
+						li);
+		} else {
+			/* Done with the dfp, free it. */
+			list_del(&dfp->dfp_list);
+			kmem_free(dfp);
+		}
 
 		if (cleanup_fn)
 			cleanup_fn(*tp, state, error);
diff --git a/fs/xfs/libxfs/xfs_ialloc_btree.c b/fs/xfs/libxfs/xfs_ialloc_btree.c
index 31ca220..eab68ae 100644
--- a/fs/xfs/libxfs/xfs_ialloc_btree.c
+++ b/fs/xfs/libxfs/xfs_ialloc_btree.c
@@ -132,7 +132,7 @@
 	xfs_rmap_ag_owner(&oinfo, XFS_RMAP_OWN_INOBT);
 	return xfs_free_extent(cur->bc_tp,
 			XFS_DADDR_TO_FSB(cur->bc_mp, XFS_BUF_ADDR(bp)), 1,
-			&oinfo);
+			&oinfo, XFS_AG_RESV_NONE);
 }
 
 STATIC int
diff --git a/fs/xfs/libxfs/xfs_log_format.h b/fs/xfs/libxfs/xfs_log_format.h
index a6eed43..fc5eef8 100644
--- a/fs/xfs/libxfs/xfs_log_format.h
+++ b/fs/xfs/libxfs/xfs_log_format.h
@@ -647,9 +647,17 @@
 	__uint16_t		rui_size;	/* size of this item */
 	__uint32_t		rui_nextents;	/* # extents to free */
 	__uint64_t		rui_id;		/* rui identifier */
-	struct xfs_map_extent	rui_extents[1];	/* array of extents to rmap */
+	struct xfs_map_extent	rui_extents[];	/* array of extents to rmap */
 };
 
+static inline size_t
+xfs_rui_log_format_sizeof(
+	unsigned int		nr)
+{
+	return sizeof(struct xfs_rui_log_format) +
+			nr * sizeof(struct xfs_map_extent);
+}
+
 /*
  * This is the structure used to lay out an rud log item in the
  * log.  The rud_extents array is a variable size array whose
diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
index 7575cfc..4a28fa9 100644
--- a/fs/xfs/xfs_aops.c
+++ b/fs/xfs/xfs_aops.c
@@ -200,7 +200,7 @@
  * Update on-disk file size now that data has been written to disk.
  */
 STATIC int
-xfs_setfilesize(
+__xfs_setfilesize(
 	struct xfs_inode	*ip,
 	struct xfs_trans	*tp,
 	xfs_off_t		offset,
@@ -225,6 +225,23 @@
 	return xfs_trans_commit(tp);
 }
 
+int
+xfs_setfilesize(
+	struct xfs_inode	*ip,
+	xfs_off_t		offset,
+	size_t			size)
+{
+	struct xfs_mount	*mp = ip->i_mount;
+	struct xfs_trans	*tp;
+	int			error;
+
+	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_fsyncts, 0, 0, 0, &tp);
+	if (error)
+		return error;
+
+	return __xfs_setfilesize(ip, tp, offset, size);
+}
+
 STATIC int
 xfs_setfilesize_ioend(
 	struct xfs_ioend	*ioend,
@@ -247,7 +264,7 @@
 		return error;
 	}
 
-	return xfs_setfilesize(ip, tp, ioend->io_offset, ioend->io_size);
+	return __xfs_setfilesize(ip, tp, ioend->io_offset, ioend->io_size);
 }
 
 /*
@@ -1336,13 +1353,12 @@
 {
 	struct inode		*inode = file_inode(iocb->ki_filp);
 	struct xfs_inode	*ip = XFS_I(inode);
-	struct xfs_mount	*mp = ip->i_mount;
 	uintptr_t		flags = (uintptr_t)private;
 	int			error = 0;
 
 	trace_xfs_end_io_direct_write(ip, offset, size);
 
-	if (XFS_FORCED_SHUTDOWN(mp))
+	if (XFS_FORCED_SHUTDOWN(ip->i_mount))
 		return -EIO;
 
 	if (size <= 0)
@@ -1380,14 +1396,9 @@
 
 		error = xfs_iomap_write_unwritten(ip, offset, size);
 	} else if (flags & XFS_DIO_FLAG_APPEND) {
-		struct xfs_trans *tp;
-
 		trace_xfs_end_io_direct_write_append(ip, offset, size);
 
-		error = xfs_trans_alloc(mp, &M_RES(mp)->tr_fsyncts, 0, 0, 0,
-				&tp);
-		if (!error)
-			error = xfs_setfilesize(ip, tp, offset, size);
+		error = xfs_setfilesize(ip, offset, size);
 	}
 
 	return error;
diff --git a/fs/xfs/xfs_aops.h b/fs/xfs/xfs_aops.h
index bf2d9a1..1950e3b 100644
--- a/fs/xfs/xfs_aops.h
+++ b/fs/xfs/xfs_aops.h
@@ -62,6 +62,7 @@
 
 int	xfs_end_io_direct_write(struct kiocb *iocb, loff_t offset,
 		ssize_t size, void *private);
+int	xfs_setfilesize(struct xfs_inode *ip, xfs_off_t offset, size_t size);
 
 extern void xfs_count_page_state(struct page *, int *, int *);
 extern struct block_device *xfs_find_bdev_for_inode(struct inode *);
diff --git a/fs/xfs/xfs_buf_item.c b/fs/xfs/xfs_buf_item.c
index e455f90..2975cb2 100644
--- a/fs/xfs/xfs_buf_item.c
+++ b/fs/xfs/xfs_buf_item.c
@@ -865,7 +865,7 @@
 	 */
 	if (bit) {
 		end_bit = MIN(bit + bits_to_set, (uint)NBWORD);
-		mask = ((1 << (end_bit - bit)) - 1) << bit;
+		mask = ((1U << (end_bit - bit)) - 1) << bit;
 		*wordp |= mask;
 		wordp++;
 		bits_set = end_bit - bit;
@@ -888,7 +888,7 @@
 	 */
 	end_bit = bits_to_set - bits_set;
 	if (end_bit) {
-		mask = (1 << end_bit) - 1;
+		mask = (1U << end_bit) - 1;
 		*wordp |= mask;
 	}
 }
@@ -1095,7 +1095,8 @@
 	     bp->b_last_error != bp->b_error) {
 		bp->b_flags |= (XBF_WRITE | XBF_DONE | XBF_WRITE_FAIL);
 		bp->b_last_error = bp->b_error;
-		if (cfg->retry_timeout && !bp->b_first_retry_time)
+		if (cfg->retry_timeout != XFS_ERR_RETRY_FOREVER &&
+		    !bp->b_first_retry_time)
 			bp->b_first_retry_time = jiffies;
 
 		xfs_buf_ioerror(bp, 0);
@@ -1111,7 +1112,7 @@
 	if (cfg->max_retries != XFS_ERR_RETRY_FOREVER &&
 	    ++bp->b_retries > cfg->max_retries)
 			goto permanent_error;
-	if (cfg->retry_timeout &&
+	if (cfg->retry_timeout != XFS_ERR_RETRY_FOREVER &&
 	    time_after(jiffies, cfg->retry_timeout + bp->b_first_retry_time))
 			goto permanent_error;
 
diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index e612a02..c68517b 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -269,6 +269,8 @@
 		return -EINVAL;
 	}
 
+	file_accessed(iocb->ki_filp);
+
 	/*
 	 * Locking is a bit tricky here. If we take an exclusive lock for direct
 	 * IO, we effectively serialise all new concurrent read IO to this file
@@ -323,7 +325,6 @@
 	}
 	xfs_rw_iunlock(ip, XFS_IOLOCK_SHARED);
 
-	file_accessed(iocb->ki_filp);
 	return ret;
 }
 
@@ -332,10 +333,7 @@
 	struct kiocb		*iocb,
 	struct iov_iter		*to)
 {
-	struct address_space	*mapping = iocb->ki_filp->f_mapping;
-	struct inode		*inode = mapping->host;
-	struct xfs_inode	*ip = XFS_I(inode);
-	struct iov_iter		data = *to;
+	struct xfs_inode	*ip = XFS_I(iocb->ki_filp->f_mapping->host);
 	size_t			count = iov_iter_count(to);
 	ssize_t			ret = 0;
 
@@ -345,11 +343,7 @@
 		return 0; /* skip atime */
 
 	xfs_rw_ilock(ip, XFS_IOLOCK_SHARED);
-	ret = dax_do_io(iocb, inode, &data, xfs_get_blocks_direct, NULL, 0);
-	if (ret > 0) {
-		iocb->ki_pos += ret;
-		iov_iter_advance(to, ret);
-	}
+	ret = iomap_dax_rw(iocb, to, &xfs_iomap_ops);
 	xfs_rw_iunlock(ip, XFS_IOLOCK_SHARED);
 
 	file_accessed(iocb->ki_filp);
@@ -711,70 +705,32 @@
 	struct kiocb		*iocb,
 	struct iov_iter		*from)
 {
-	struct address_space	*mapping = iocb->ki_filp->f_mapping;
-	struct inode		*inode = mapping->host;
+	struct inode		*inode = iocb->ki_filp->f_mapping->host;
 	struct xfs_inode	*ip = XFS_I(inode);
-	struct xfs_mount	*mp = ip->i_mount;
-	ssize_t			ret = 0;
-	int			unaligned_io = 0;
-	int			iolock;
-	struct iov_iter		data;
+	int			iolock = XFS_IOLOCK_EXCL;
+	ssize_t			ret, error = 0;
+	size_t			count;
+	loff_t			pos;
 
-	/* "unaligned" here means not aligned to a filesystem block */
-	if ((iocb->ki_pos & mp->m_blockmask) ||
-	    ((iocb->ki_pos + iov_iter_count(from)) & mp->m_blockmask)) {
-		unaligned_io = 1;
-		iolock = XFS_IOLOCK_EXCL;
-	} else if (mapping->nrpages) {
-		iolock = XFS_IOLOCK_EXCL;
-	} else {
-		iolock = XFS_IOLOCK_SHARED;
-	}
 	xfs_rw_ilock(ip, iolock);
-
 	ret = xfs_file_aio_write_checks(iocb, from, &iolock);
 	if (ret)
 		goto out;
 
-	/*
-	 * Yes, even DAX files can have page cache attached to them:  A zeroed
-	 * page is inserted into the pagecache when we have to serve a write
-	 * fault on a hole.  It should never be dirtied and can simply be
-	 * dropped from the pagecache once we get real data for the page.
-	 *
-	 * XXX: This is racy against mmap, and there's nothing we can do about
-	 * it. dax_do_io() should really do this invalidation internally as
-	 * it will know if we've allocated over a holei for this specific IO and
-	 * if so it needs to update the mapping tree and invalidate existing
-	 * PTEs over the newly allocated range. Remove this invalidation when
-	 * dax_do_io() is fixed up.
-	 */
-	if (mapping->nrpages) {
-		loff_t end = iocb->ki_pos + iov_iter_count(from) - 1;
+	pos = iocb->ki_pos;
+	count = iov_iter_count(from);
 
-		ret = invalidate_inode_pages2_range(mapping,
-						    iocb->ki_pos >> PAGE_SHIFT,
-						    end >> PAGE_SHIFT);
-		WARN_ON_ONCE(ret);
+	trace_xfs_file_dax_write(ip, count, pos);
+
+	ret = iomap_dax_rw(iocb, from, &xfs_iomap_ops);
+	if (ret > 0 && iocb->ki_pos > i_size_read(inode)) {
+		i_size_write(inode, iocb->ki_pos);
+		error = xfs_setfilesize(ip, pos, ret);
 	}
 
-	if (iolock == XFS_IOLOCK_EXCL && !unaligned_io) {
-		xfs_rw_ilock_demote(ip, XFS_IOLOCK_EXCL);
-		iolock = XFS_IOLOCK_SHARED;
-	}
-
-	trace_xfs_file_dax_write(ip, iov_iter_count(from), iocb->ki_pos);
-
-	data = *from;
-	ret = dax_do_io(iocb, inode, &data, xfs_get_blocks_direct,
-			xfs_end_io_direct_write, 0);
-	if (ret > 0) {
-		iocb->ki_pos += ret;
-		iov_iter_advance(from, ret);
-	}
 out:
 	xfs_rw_iunlock(ip, iolock);
-	return ret;
+	return error ? error : ret;
 }
 
 STATIC ssize_t
@@ -1513,7 +1469,7 @@
 	xfs_ilock(XFS_I(inode), XFS_MMAPLOCK_SHARED);
 
 	if (IS_DAX(inode)) {
-		ret = dax_mkwrite(vma, vmf, xfs_get_blocks_dax_fault);
+		ret = iomap_dax_fault(vma, vmf, &xfs_iomap_ops);
 	} else {
 		ret = iomap_page_mkwrite(vma, vmf, &xfs_iomap_ops);
 		ret = block_page_mkwrite_return(ret);
@@ -1547,7 +1503,7 @@
 		 * changes to xfs_get_blocks_direct() to map unwritten extent
 		 * ioend for conversion on read-only mappings.
 		 */
-		ret = dax_fault(vma, vmf, xfs_get_blocks_dax_fault);
+		ret = iomap_dax_fault(vma, vmf, &xfs_iomap_ops);
 	} else
 		ret = filemap_fault(vma, vmf);
 	xfs_iunlock(XFS_I(inode), XFS_MMAPLOCK_SHARED);
diff --git a/fs/xfs/xfs_filestream.c b/fs/xfs/xfs_filestream.c
index a75f7ab..043ca380 100644
--- a/fs/xfs/xfs_filestream.c
+++ b/fs/xfs/xfs_filestream.c
@@ -30,6 +30,7 @@
 #include "xfs_mru_cache.h"
 #include "xfs_filestream.h"
 #include "xfs_trace.h"
+#include "xfs_ag_resv.h"
 
 struct xfs_fstrm_item {
 	struct xfs_mru_cache_elem	mru;
@@ -198,7 +199,8 @@
 		}
 
 		longest = xfs_alloc_longest_free_extent(mp, pag,
-					xfs_alloc_min_freelist(mp, pag));
+				xfs_alloc_min_freelist(mp, pag),
+				xfs_ag_resv_needed(pag, XFS_AG_RESV_NONE));
 		if (((minlen && longest >= minlen) ||
 		     (!minlen && pag->pagf_freeblks >= minfree)) &&
 		    (!pag->pagf_metadata || !(flags & XFS_PICK_USERDATA) ||
diff --git a/fs/xfs/xfs_fsops.c b/fs/xfs/xfs_fsops.c
index 0b7f986..94ac06f 100644
--- a/fs/xfs/xfs_fsops.c
+++ b/fs/xfs/xfs_fsops.c
@@ -553,7 +553,7 @@
 		error = xfs_free_extent(tp,
 				XFS_AGB_TO_FSB(mp, agno,
 					be32_to_cpu(agf->agf_length) - new),
-				new, &oinfo);
+				new, &oinfo, XFS_AG_RESV_NONE);
 		if (error)
 			goto error0;
 	}
diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c
index fb39a66..65b2e3f 100644
--- a/fs/xfs/xfs_icache.c
+++ b/fs/xfs/xfs_icache.c
@@ -1414,6 +1414,16 @@
 	struct xfs_perag *pag;
 	int tagged;
 
+	/*
+	 * Don't bother locking the AG and looking up in the radix trees
+	 * if we already know that we have the tag set.
+	 */
+	if (ip->i_flags & XFS_IEOFBLOCKS)
+		return;
+	spin_lock(&ip->i_flags_lock);
+	ip->i_flags |= XFS_IEOFBLOCKS;
+	spin_unlock(&ip->i_flags_lock);
+
 	pag = xfs_perag_get(mp, XFS_INO_TO_AGNO(mp, ip->i_ino));
 	spin_lock(&pag->pag_ici_lock);
 	trace_xfs_inode_set_eofblocks_tag(ip);
@@ -1449,6 +1459,10 @@
 	struct xfs_mount *mp = ip->i_mount;
 	struct xfs_perag *pag;
 
+	spin_lock(&ip->i_flags_lock);
+	ip->i_flags &= ~XFS_IEOFBLOCKS;
+	spin_unlock(&ip->i_flags_lock);
+
 	pag = xfs_perag_get(mp, XFS_INO_TO_AGNO(mp, ip->i_ino));
 	spin_lock(&pag->pag_ici_lock);
 	trace_xfs_inode_clear_eofblocks_tag(ip);
diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h
index e1a411e..8f30d25 100644
--- a/fs/xfs/xfs_inode.h
+++ b/fs/xfs/xfs_inode.h
@@ -216,6 +216,7 @@
 #define __XFS_IPINNED_BIT	8	 /* wakeup key for zero pin count */
 #define XFS_IPINNED		(1 << __XFS_IPINNED_BIT)
 #define XFS_IDONTCACHE		(1 << 9) /* don't cache the inode long term */
+#define XFS_IEOFBLOCKS		(1 << 10)/* has the preallocblocks tag set */
 
 /*
  * Per-lifetime flags need to be reset when re-using a reclaimable inode during
diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
index 2af0dda..c08253e 100644
--- a/fs/xfs/xfs_iomap.c
+++ b/fs/xfs/xfs_iomap.c
@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2000-2006 Silicon Graphics, Inc.
+ * Copyright (c) 2016 Christoph Hellwig.
  * All Rights Reserved.
  *
  * This program is free software; you can redistribute it and/or
@@ -42,17 +43,40 @@
 
 #define XFS_WRITEIO_ALIGN(mp,off)	(((off) >> mp->m_writeio_log) \
 						<< mp->m_writeio_log)
-#define XFS_WRITE_IMAPS		XFS_BMAP_MAX_NMAP
 
-STATIC int
-xfs_iomap_eof_align_last_fsb(
-	xfs_mount_t	*mp,
-	xfs_inode_t	*ip,
-	xfs_extlen_t	extsize,
-	xfs_fileoff_t	*last_fsb)
+void
+xfs_bmbt_to_iomap(
+	struct xfs_inode	*ip,
+	struct iomap		*iomap,
+	struct xfs_bmbt_irec	*imap)
 {
-	xfs_extlen_t	align = 0;
-	int		eof, error;
+	struct xfs_mount	*mp = ip->i_mount;
+
+	if (imap->br_startblock == HOLESTARTBLOCK) {
+		iomap->blkno = IOMAP_NULL_BLOCK;
+		iomap->type = IOMAP_HOLE;
+	} else if (imap->br_startblock == DELAYSTARTBLOCK) {
+		iomap->blkno = IOMAP_NULL_BLOCK;
+		iomap->type = IOMAP_DELALLOC;
+	} else {
+		iomap->blkno = xfs_fsb_to_db(ip, imap->br_startblock);
+		if (imap->br_state == XFS_EXT_UNWRITTEN)
+			iomap->type = IOMAP_UNWRITTEN;
+		else
+			iomap->type = IOMAP_MAPPED;
+	}
+	iomap->offset = XFS_FSB_TO_B(mp, imap->br_startoff);
+	iomap->length = XFS_FSB_TO_B(mp, imap->br_blockcount);
+	iomap->bdev = xfs_find_bdev_for_inode(VFS_I(ip));
+}
+
+static xfs_extlen_t
+xfs_eof_alignment(
+	struct xfs_inode	*ip,
+	xfs_extlen_t		extsize)
+{
+	struct xfs_mount	*mp = ip->i_mount;
+	xfs_extlen_t		align = 0;
 
 	if (!XFS_IS_REALTIME_INODE(ip)) {
 		/*
@@ -83,8 +107,21 @@
 			align = extsize;
 	}
 
+	return align;
+}
+
+STATIC int
+xfs_iomap_eof_align_last_fsb(
+	struct xfs_inode	*ip,
+	xfs_extlen_t		extsize,
+	xfs_fileoff_t		*last_fsb)
+{
+	xfs_extlen_t		align = xfs_eof_alignment(ip, extsize);
+
 	if (align) {
 		xfs_fileoff_t	new_last_fsb = roundup_64(*last_fsb, align);
+		int		eof, error;
+
 		error = xfs_bmap_eof(ip, new_last_fsb, XFS_DATA_FORK, &eof);
 		if (error)
 			return error;
@@ -154,7 +191,7 @@
 		 */
 		ASSERT(XFS_IFORK_PTR(ip, XFS_DATA_FORK)->if_flags &
 								XFS_IFEXTENTS);
-		error = xfs_iomap_eof_align_last_fsb(mp, ip, extsz, &last_fsb);
+		error = xfs_iomap_eof_align_last_fsb(ip, extsz, &last_fsb);
 		if (error)
 			goto out_unlock;
 	} else {
@@ -274,130 +311,6 @@
 	goto out_unlock;
 }
 
-/*
- * If the caller is doing a write at the end of the file, then extend the
- * allocation out to the file system's write iosize.  We clean up any extra
- * space left over when the file is closed in xfs_inactive().
- *
- * If we find we already have delalloc preallocation beyond EOF, don't do more
- * preallocation as it it not needed.
- */
-STATIC int
-xfs_iomap_eof_want_preallocate(
-	xfs_mount_t	*mp,
-	xfs_inode_t	*ip,
-	xfs_off_t	offset,
-	size_t		count,
-	xfs_bmbt_irec_t *imap,
-	int		nimaps,
-	int		*prealloc)
-{
-	xfs_fileoff_t   start_fsb;
-	xfs_filblks_t   count_fsb;
-	int		n, error, imaps;
-	int		found_delalloc = 0;
-
-	*prealloc = 0;
-	if (offset + count <= XFS_ISIZE(ip))
-		return 0;
-
-	/*
-	 * If the file is smaller than the minimum prealloc and we are using
-	 * dynamic preallocation, don't do any preallocation at all as it is
-	 * likely this is the only write to the file that is going to be done.
-	 */
-	if (!(mp->m_flags & XFS_MOUNT_DFLT_IOSIZE) &&
-	    XFS_ISIZE(ip) < XFS_FSB_TO_B(mp, mp->m_writeio_blocks))
-		return 0;
-
-	/*
-	 * If there are any real blocks past eof, then don't
-	 * do any speculative allocation.
-	 */
-	start_fsb = XFS_B_TO_FSBT(mp, ((xfs_ufsize_t)(offset + count - 1)));
-	count_fsb = XFS_B_TO_FSB(mp, mp->m_super->s_maxbytes);
-	while (count_fsb > 0) {
-		imaps = nimaps;
-		error = xfs_bmapi_read(ip, start_fsb, count_fsb, imap, &imaps,
-				       0);
-		if (error)
-			return error;
-		for (n = 0; n < imaps; n++) {
-			if ((imap[n].br_startblock != HOLESTARTBLOCK) &&
-			    (imap[n].br_startblock != DELAYSTARTBLOCK))
-				return 0;
-			start_fsb += imap[n].br_blockcount;
-			count_fsb -= imap[n].br_blockcount;
-
-			if (imap[n].br_startblock == DELAYSTARTBLOCK)
-				found_delalloc = 1;
-		}
-	}
-	if (!found_delalloc)
-		*prealloc = 1;
-	return 0;
-}
-
-/*
- * Determine the initial size of the preallocation. We are beyond the current
- * EOF here, but we need to take into account whether this is a sparse write or
- * an extending write when determining the preallocation size.  Hence we need to
- * look up the extent that ends at the current write offset and use the result
- * to determine the preallocation size.
- *
- * If the extent is a hole, then preallocation is essentially disabled.
- * Otherwise we take the size of the preceeding data extent as the basis for the
- * preallocation size. If the size of the extent is greater than half the
- * maximum extent length, then use the current offset as the basis. This ensures
- * that for large files the preallocation size always extends to MAXEXTLEN
- * rather than falling short due to things like stripe unit/width alignment of
- * real extents.
- */
-STATIC xfs_fsblock_t
-xfs_iomap_eof_prealloc_initial_size(
-	struct xfs_mount	*mp,
-	struct xfs_inode	*ip,
-	xfs_off_t		offset,
-	xfs_bmbt_irec_t		*imap,
-	int			nimaps)
-{
-	xfs_fileoff_t   start_fsb;
-	int		imaps = 1;
-	int		error;
-
-	ASSERT(nimaps >= imaps);
-
-	/* if we are using a specific prealloc size, return now */
-	if (mp->m_flags & XFS_MOUNT_DFLT_IOSIZE)
-		return 0;
-
-	/* If the file is small, then use the minimum prealloc */
-	if (XFS_ISIZE(ip) < XFS_FSB_TO_B(mp, mp->m_dalign))
-		return 0;
-
-	/*
-	 * As we write multiple pages, the offset will always align to the
-	 * start of a page and hence point to a hole at EOF. i.e. if the size is
-	 * 4096 bytes, we only have one block at FSB 0, but XFS_B_TO_FSB(4096)
-	 * will return FSB 1. Hence if there are blocks in the file, we want to
-	 * point to the block prior to the EOF block and not the hole that maps
-	 * directly at @offset.
-	 */
-	start_fsb = XFS_B_TO_FSB(mp, offset);
-	if (start_fsb)
-		start_fsb--;
-	error = xfs_bmapi_read(ip, start_fsb, 1, imap, &imaps, XFS_BMAPI_ENTIRE);
-	if (error)
-		return 0;
-
-	ASSERT(imaps == 1);
-	if (imap[0].br_startblock == HOLESTARTBLOCK)
-		return 0;
-	if (imap[0].br_blockcount <= (MAXEXTLEN >> 1))
-		return imap[0].br_blockcount << 1;
-	return XFS_B_TO_FSB(mp, offset);
-}
-
 STATIC bool
 xfs_quota_need_throttle(
 	struct xfs_inode *ip,
@@ -459,27 +372,76 @@
 }
 
 /*
+ * If we are doing a write at the end of the file and there are no allocations
+ * past this one, then extend the allocation out to the file system's write
+ * iosize.
+ *
  * If we don't have a user specified preallocation size, dynamically increase
- * the preallocation size as the size of the file grows. Cap the maximum size
+ * the preallocation size as the size of the file grows.  Cap the maximum size
  * at a single extent or less if the filesystem is near full. The closer the
  * filesystem is to full, the smaller the maximum prealocation.
+ *
+ * As an exception we don't do any preallocation at all if the file is smaller
+ * than the minimum preallocation and we are using the default dynamic
+ * preallocation scheme, as it is likely this is the only write to the file that
+ * is going to be done.
+ *
+ * We clean up any extra space left over when the file is closed in
+ * xfs_inactive().
  */
 STATIC xfs_fsblock_t
 xfs_iomap_prealloc_size(
-	struct xfs_mount	*mp,
 	struct xfs_inode	*ip,
-	xfs_off_t		offset,
-	struct xfs_bmbt_irec	*imap,
-	int			nimaps)
+	loff_t			offset,
+	loff_t			count,
+	xfs_extnum_t		idx,
+	struct xfs_bmbt_irec	*prev)
 {
-	xfs_fsblock_t		alloc_blocks = 0;
+	struct xfs_mount	*mp = ip->i_mount;
+	xfs_fileoff_t		offset_fsb = XFS_B_TO_FSBT(mp, offset);
 	int			shift = 0;
 	int64_t			freesp;
 	xfs_fsblock_t		qblocks;
 	int			qshift = 0;
+	xfs_fsblock_t		alloc_blocks = 0;
 
-	alloc_blocks = xfs_iomap_eof_prealloc_initial_size(mp, ip, offset,
-							   imap, nimaps);
+	if (offset + count <= XFS_ISIZE(ip))
+		return 0;
+
+	if (!(mp->m_flags & XFS_MOUNT_DFLT_IOSIZE) &&
+	    (XFS_ISIZE(ip) < XFS_FSB_TO_B(mp, mp->m_writeio_blocks)))
+		return 0;
+
+	/*
+	 * If an explicit allocsize is set, the file is small, or we
+	 * are writing behind a hole, then use the minimum prealloc:
+	 */
+	if ((mp->m_flags & XFS_MOUNT_DFLT_IOSIZE) ||
+	    XFS_ISIZE(ip) < XFS_FSB_TO_B(mp, mp->m_dalign) ||
+	    idx == 0 ||
+	    prev->br_startoff + prev->br_blockcount < offset_fsb)
+		return mp->m_writeio_blocks;
+
+	/*
+	 * Determine the initial size of the preallocation. We are beyond the
+	 * current EOF here, but we need to take into account whether this is
+	 * a sparse write or an extending write when determining the
+	 * preallocation size.  Hence we need to look up the extent that ends
+	 * at the current write offset and use the result to determine the
+	 * preallocation size.
+	 *
+	 * If the extent is a hole, then preallocation is essentially disabled.
+	 * Otherwise we take the size of the preceding data extent as the basis
+	 * for the preallocation size. If the size of the extent is greater than
+	 * half the maximum extent length, then use the current offset as the
+	 * basis. This ensures that for large files the preallocation size
+	 * always extends to MAXEXTLEN rather than falling short due to things
+	 * like stripe unit/width alignment of real extents.
+	 */
+	if (prev->br_blockcount <= (MAXEXTLEN >> 1))
+		alloc_blocks = prev->br_blockcount << 1;
+	else
+		alloc_blocks = XFS_B_TO_FSB(mp, offset);
 	if (!alloc_blocks)
 		goto check_writeio;
 	qblocks = alloc_blocks;
@@ -550,120 +512,145 @@
 	 */
 	while (alloc_blocks && alloc_blocks >= freesp)
 		alloc_blocks >>= 4;
-
 check_writeio:
 	if (alloc_blocks < mp->m_writeio_blocks)
 		alloc_blocks = mp->m_writeio_blocks;
-
 	trace_xfs_iomap_prealloc_size(ip, alloc_blocks, shift,
 				      mp->m_writeio_blocks);
-
 	return alloc_blocks;
 }
 
-int
-xfs_iomap_write_delay(
-	xfs_inode_t	*ip,
-	xfs_off_t	offset,
-	size_t		count,
-	xfs_bmbt_irec_t *ret_imap)
+static int
+xfs_file_iomap_begin_delay(
+	struct inode		*inode,
+	loff_t			offset,
+	loff_t			count,
+	unsigned		flags,
+	struct iomap		*iomap)
 {
-	xfs_mount_t	*mp = ip->i_mount;
-	xfs_fileoff_t	offset_fsb;
-	xfs_fileoff_t	last_fsb;
-	xfs_off_t	aligned_offset;
-	xfs_fileoff_t	ioalign;
-	xfs_extlen_t	extsz;
-	int		nimaps;
-	xfs_bmbt_irec_t imap[XFS_WRITE_IMAPS];
-	int		prealloc;
-	int		error;
+	struct xfs_inode	*ip = XFS_I(inode);
+	struct xfs_mount	*mp = ip->i_mount;
+	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, XFS_DATA_FORK);
+	xfs_fileoff_t		offset_fsb = XFS_B_TO_FSBT(mp, offset);
+	xfs_fileoff_t		maxbytes_fsb =
+		XFS_B_TO_FSB(mp, mp->m_super->s_maxbytes);
+	xfs_fileoff_t		end_fsb, orig_end_fsb;
+	int			error = 0, eof = 0;
+	struct xfs_bmbt_irec	got;
+	struct xfs_bmbt_irec	prev;
+	xfs_extnum_t		idx;
 
-	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
+	ASSERT(!XFS_IS_REALTIME_INODE(ip));
+	ASSERT(!xfs_get_extsz_hint(ip));
 
-	/*
-	 * Make sure that the dquots are there. This doesn't hold
-	 * the ilock across a disk read.
-	 */
+	xfs_ilock(ip, XFS_ILOCK_EXCL);
+
+	if (unlikely(XFS_TEST_ERROR(
+	    (XFS_IFORK_FORMAT(ip, XFS_DATA_FORK) != XFS_DINODE_FMT_EXTENTS &&
+	     XFS_IFORK_FORMAT(ip, XFS_DATA_FORK) != XFS_DINODE_FMT_BTREE),
+	     mp, XFS_ERRTAG_BMAPIFORMAT, XFS_RANDOM_BMAPIFORMAT))) {
+		XFS_ERROR_REPORT(__func__, XFS_ERRLEVEL_LOW, mp);
+		error = -EFSCORRUPTED;
+		goto out_unlock;
+	}
+
+	XFS_STATS_INC(mp, xs_blk_mapw);
+
+	if (!(ifp->if_flags & XFS_IFEXTENTS)) {
+		error = xfs_iread_extents(NULL, ip, XFS_DATA_FORK);
+		if (error)
+			goto out_unlock;
+	}
+
+	xfs_bmap_search_extents(ip, offset_fsb, XFS_DATA_FORK, &eof, &idx,
+			&got, &prev);
+	if (!eof && got.br_startoff <= offset_fsb) {
+		trace_xfs_iomap_found(ip, offset, count, 0, &got);
+		goto done;
+	}
+
 	error = xfs_qm_dqattach_locked(ip, 0);
 	if (error)
-		return error;
+		goto out_unlock;
 
-	extsz = xfs_get_extsz_hint(ip);
-	offset_fsb = XFS_B_TO_FSBT(mp, offset);
+	/*
+	 * We cap the maximum length we map here to MAX_WRITEBACK_PAGES pages
+	 * to keep the chunks of work done where somewhat symmetric with the
+	 * work writeback does. This is a completely arbitrary number pulled
+	 * out of thin air as a best guess for initial testing.
+	 *
+	 * Note that the values needs to be less than 32-bits wide until
+	 * the lower level functions are updated.
+	 */
+	count = min_t(loff_t, count, 1024 * PAGE_SIZE);
+	end_fsb = orig_end_fsb =
+		min(XFS_B_TO_FSB(mp, offset + count), maxbytes_fsb);
 
-	error = xfs_iomap_eof_want_preallocate(mp, ip, offset, count,
-				imap, XFS_WRITE_IMAPS, &prealloc);
-	if (error)
-		return error;
+	if (eof) {
+		xfs_fsblock_t	prealloc_blocks;
+
+		prealloc_blocks =
+			xfs_iomap_prealloc_size(ip, offset, count, idx, &prev);
+		if (prealloc_blocks) {
+			xfs_extlen_t	align;
+			xfs_off_t	end_offset;
+
+			end_offset = XFS_WRITEIO_ALIGN(mp, offset + count - 1);
+			end_fsb = XFS_B_TO_FSBT(mp, end_offset) +
+				prealloc_blocks;
+
+			align = xfs_eof_alignment(ip, 0);
+			if (align)
+				end_fsb = roundup_64(end_fsb, align);
+
+			end_fsb = min(end_fsb, maxbytes_fsb);
+			ASSERT(end_fsb > offset_fsb);
+		}
+	}
 
 retry:
-	if (prealloc) {
-		xfs_fsblock_t	alloc_blocks;
-
-		alloc_blocks = xfs_iomap_prealloc_size(mp, ip, offset, imap,
-						       XFS_WRITE_IMAPS);
-
-		aligned_offset = XFS_WRITEIO_ALIGN(mp, (offset + count - 1));
-		ioalign = XFS_B_TO_FSBT(mp, aligned_offset);
-		last_fsb = ioalign + alloc_blocks;
-	} else {
-		last_fsb = XFS_B_TO_FSB(mp, ((xfs_ufsize_t)(offset + count)));
-	}
-
-	if (prealloc || extsz) {
-		error = xfs_iomap_eof_align_last_fsb(mp, ip, extsz, &last_fsb);
-		if (error)
-			return error;
-	}
-
-	/*
-	 * Make sure preallocation does not create extents beyond the range we
-	 * actually support in this filesystem.
-	 */
-	if (last_fsb > XFS_B_TO_FSB(mp, mp->m_super->s_maxbytes))
-		last_fsb = XFS_B_TO_FSB(mp, mp->m_super->s_maxbytes);
-
-	ASSERT(last_fsb > offset_fsb);
-
-	nimaps = XFS_WRITE_IMAPS;
-	error = xfs_bmapi_delay(ip, offset_fsb, last_fsb - offset_fsb,
-				imap, &nimaps, XFS_BMAPI_ENTIRE);
+	error = xfs_bmapi_reserve_delalloc(ip, offset_fsb,
+			end_fsb - offset_fsb, &got,
+			&prev, &idx, eof);
 	switch (error) {
 	case 0:
+		break;
 	case -ENOSPC:
 	case -EDQUOT:
-		break;
-	default:
-		return error;
-	}
-
-	/*
-	 * If bmapi returned us nothing, we got either ENOSPC or EDQUOT. Retry
-	 * without EOF preallocation.
-	 */
-	if (nimaps == 0) {
+		/* retry without any preallocation */
 		trace_xfs_delalloc_enospc(ip, offset, count);
-		if (prealloc) {
-			prealloc = 0;
-			error = 0;
+		if (end_fsb != orig_end_fsb) {
+			end_fsb = orig_end_fsb;
 			goto retry;
 		}
-		return error ? error : -ENOSPC;
+		/*FALLTHRU*/
+	default:
+		goto out_unlock;
 	}
 
-	if (!(imap[0].br_startblock || XFS_IS_REALTIME_INODE(ip)))
-		return xfs_alert_fsblock_zero(ip, &imap[0]);
-
 	/*
 	 * Tag the inode as speculatively preallocated so we can reclaim this
 	 * space on demand, if necessary.
 	 */
-	if (prealloc)
+	if (end_fsb != orig_end_fsb)
 		xfs_inode_set_eofblocks_tag(ip);
 
-	*ret_imap = imap[0];
-	return 0;
+	trace_xfs_iomap_alloc(ip, offset, count, 0, &got);
+done:
+	if (isnullstartblock(got.br_startblock))
+		got.br_startblock = DELAYSTARTBLOCK;
+
+	if (!got.br_startblock) {
+		error = xfs_alert_fsblock_zero(ip, &got);
+		if (error)
+			goto out_unlock;
+	}
+
+	xfs_bmbt_to_iomap(ip, iomap, &got);
+
+out_unlock:
+	xfs_iunlock(ip, XFS_ILOCK_EXCL);
+	return error;
 }
 
 /*
@@ -947,37 +934,13 @@
 	return error;
 }
 
-void
-xfs_bmbt_to_iomap(
-	struct xfs_inode	*ip,
-	struct iomap		*iomap,
-	struct xfs_bmbt_irec	*imap)
-{
-	struct xfs_mount	*mp = ip->i_mount;
-
-	if (imap->br_startblock == HOLESTARTBLOCK) {
-		iomap->blkno = IOMAP_NULL_BLOCK;
-		iomap->type = IOMAP_HOLE;
-	} else if (imap->br_startblock == DELAYSTARTBLOCK) {
-		iomap->blkno = IOMAP_NULL_BLOCK;
-		iomap->type = IOMAP_DELALLOC;
-	} else {
-		iomap->blkno = xfs_fsb_to_db(ip, imap->br_startblock);
-		if (imap->br_state == XFS_EXT_UNWRITTEN)
-			iomap->type = IOMAP_UNWRITTEN;
-		else
-			iomap->type = IOMAP_MAPPED;
-	}
-	iomap->offset = XFS_FSB_TO_B(mp, imap->br_startoff);
-	iomap->length = XFS_FSB_TO_B(mp, imap->br_blockcount);
-	iomap->bdev = xfs_find_bdev_for_inode(VFS_I(ip));
-}
-
-static inline bool imap_needs_alloc(struct xfs_bmbt_irec *imap, int nimaps)
+static inline bool imap_needs_alloc(struct inode *inode,
+		struct xfs_bmbt_irec *imap, int nimaps)
 {
 	return !nimaps ||
 		imap->br_startblock == HOLESTARTBLOCK ||
-		imap->br_startblock == DELAYSTARTBLOCK;
+		imap->br_startblock == DELAYSTARTBLOCK ||
+		(IS_DAX(inode) && ISUNWRITTEN(imap));
 }
 
 static int
@@ -993,11 +956,18 @@
 	struct xfs_bmbt_irec	imap;
 	xfs_fileoff_t		offset_fsb, end_fsb;
 	int			nimaps = 1, error = 0;
+	unsigned		lockmode;
 
 	if (XFS_FORCED_SHUTDOWN(mp))
 		return -EIO;
 
-	xfs_ilock(ip, XFS_ILOCK_EXCL);
+	if ((flags & IOMAP_WRITE) &&
+	    !IS_DAX(inode) && !xfs_get_extsz_hint(ip)) {
+		return xfs_file_iomap_begin_delay(inode, offset, length, flags,
+				iomap);
+	}
+
+	lockmode = xfs_ilock_data_map_shared(ip);
 
 	ASSERT(offset <= mp->m_super->s_maxbytes);
 	if ((xfs_fsize_t)offset + length > mp->m_super->s_maxbytes)
@@ -1008,11 +978,11 @@
 	error = xfs_bmapi_read(ip, offset_fsb, end_fsb - offset_fsb, &imap,
 			       &nimaps, XFS_BMAPI_ENTIRE);
 	if (error) {
-		xfs_iunlock(ip, XFS_ILOCK_EXCL);
+		xfs_iunlock(ip, lockmode);
 		return error;
 	}
 
-	if ((flags & IOMAP_WRITE) && imap_needs_alloc(&imap, nimaps)) {
+	if ((flags & IOMAP_WRITE) && imap_needs_alloc(inode, &imap, nimaps)) {
 		/*
 		 * We cap the maximum length we map here to MAX_WRITEBACK_PAGES
 		 * pages to keep the chunks of work done where somewhat symmetric
@@ -1024,27 +994,23 @@
 		 * the lower level functions are updated.
 		 */
 		length = min_t(loff_t, length, 1024 * PAGE_SIZE);
-		if (xfs_get_extsz_hint(ip)) {
-			/*
-			 * xfs_iomap_write_direct() expects the shared lock. It
-			 * is unlocked on return.
-			 */
-			xfs_ilock_demote(ip, XFS_ILOCK_EXCL);
-			error = xfs_iomap_write_direct(ip, offset, length, &imap,
-					nimaps);
-		} else {
-			error = xfs_iomap_write_delay(ip, offset, length, &imap);
-			xfs_iunlock(ip, XFS_ILOCK_EXCL);
-		}
-
+		/*
+		 * xfs_iomap_write_direct() expects the shared lock. It
+		 * is unlocked on return.
+		 */
+		if (lockmode == XFS_ILOCK_EXCL)
+			xfs_ilock_demote(ip, lockmode);
+		error = xfs_iomap_write_direct(ip, offset, length, &imap,
+				nimaps);
 		if (error)
 			return error;
 
+		iomap->flags = IOMAP_F_NEW;
 		trace_xfs_iomap_alloc(ip, offset, length, 0, &imap);
 	} else {
 		ASSERT(nimaps);
 
-		xfs_iunlock(ip, XFS_ILOCK_EXCL);
+		xfs_iunlock(ip, lockmode);
 		trace_xfs_iomap_found(ip, offset, length, 0, &imap);
 	}
 
diff --git a/fs/xfs/xfs_iomap.h b/fs/xfs/xfs_iomap.h
index fb8aca3..6498be4 100644
--- a/fs/xfs/xfs_iomap.h
+++ b/fs/xfs/xfs_iomap.h
@@ -25,8 +25,6 @@
 
 int xfs_iomap_write_direct(struct xfs_inode *, xfs_off_t, size_t,
 			struct xfs_bmbt_irec *, int);
-int xfs_iomap_write_delay(struct xfs_inode *, xfs_off_t, size_t,
-			struct xfs_bmbt_irec *);
 int xfs_iomap_write_allocate(struct xfs_inode *, xfs_off_t,
 			struct xfs_bmbt_irec *);
 int xfs_iomap_write_unwritten(struct xfs_inode *, xfs_off_t, xfs_off_t);
diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h
index b36676c..041d949 100644
--- a/fs/xfs/xfs_mount.h
+++ b/fs/xfs/xfs_mount.h
@@ -57,10 +57,16 @@
 
 #define XFS_ERR_RETRY_FOREVER	-1
 
+/*
+ * Although retry_timeout is in jiffies which is normally an unsigned long,
+ * we limit the retry timeout to 86400 seconds, or one day.  So even a
+ * signed 32-bit long is sufficient for a HZ value up to 24855.  Making it
+ * signed lets us store the special "-1" value, meaning retry forever.
+ */
 struct xfs_error_cfg {
 	struct xfs_kobj	kobj;
 	int		max_retries;
-	unsigned long	retry_timeout;	/* in jiffies, 0 = no timeout */
+	long		retry_timeout;	/* in jiffies, -1 = infinite */
 };
 
 typedef struct xfs_mount {
@@ -325,6 +331,22 @@
 }
 #endif
 
+/* per-AG block reservation data structures*/
+enum xfs_ag_resv_type {
+	XFS_AG_RESV_NONE = 0,
+	XFS_AG_RESV_METADATA,
+	XFS_AG_RESV_AGFL,
+};
+
+struct xfs_ag_resv {
+	/* number of blocks originally reserved here */
+	xfs_extlen_t			ar_orig_reserved;
+	/* number of blocks reserved here */
+	xfs_extlen_t			ar_reserved;
+	/* number of blocks originally asked for */
+	xfs_extlen_t			ar_asked;
+};
+
 /*
  * Per-ag incore structure, copies of information in agf and agi, to improve the
  * performance of allocation group selection.
@@ -372,8 +394,28 @@
 	/* for rcu-safe freeing */
 	struct rcu_head	rcu_head;
 	int		pagb_count;	/* pagb slots in use */
+
+	/* Blocks reserved for all kinds of metadata. */
+	struct xfs_ag_resv	pag_meta_resv;
+	/* Blocks reserved for just AGFL-based metadata. */
+	struct xfs_ag_resv	pag_agfl_resv;
 } xfs_perag_t;
 
+static inline struct xfs_ag_resv *
+xfs_perag_resv(
+	struct xfs_perag	*pag,
+	enum xfs_ag_resv_type	type)
+{
+	switch (type) {
+	case XFS_AG_RESV_METADATA:
+		return &pag->pag_meta_resv;
+	case XFS_AG_RESV_AGFL:
+		return &pag->pag_agfl_resv;
+	default:
+		return NULL;
+	}
+}
+
 extern void	xfs_uuid_table_free(void);
 extern int	xfs_log_sbcount(xfs_mount_t *);
 extern __uint64_t xfs_default_resblks(xfs_mount_t *mp);
diff --git a/fs/xfs/xfs_rmap_item.c b/fs/xfs/xfs_rmap_item.c
index 2500f286..0432a45 100644
--- a/fs/xfs/xfs_rmap_item.c
+++ b/fs/xfs/xfs_rmap_item.c
@@ -51,28 +51,16 @@
 		kmem_zone_free(xfs_rui_zone, ruip);
 }
 
-/*
- * This returns the number of iovecs needed to log the given rui item.
- * We only need 1 iovec for an rui item.  It just logs the rui_log_format
- * structure.
- */
-static inline int
-xfs_rui_item_sizeof(
-	struct xfs_rui_log_item *ruip)
-{
-	return sizeof(struct xfs_rui_log_format) +
-			(ruip->rui_format.rui_nextents - 1) *
-			sizeof(struct xfs_map_extent);
-}
-
 STATIC void
 xfs_rui_item_size(
 	struct xfs_log_item	*lip,
 	int			*nvecs,
 	int			*nbytes)
 {
+	struct xfs_rui_log_item	*ruip = RUI_ITEM(lip);
+
 	*nvecs += 1;
-	*nbytes += xfs_rui_item_sizeof(RUI_ITEM(lip));
+	*nbytes += xfs_rui_log_format_sizeof(ruip->rui_format.rui_nextents);
 }
 
 /*
@@ -97,7 +85,7 @@
 	ruip->rui_format.rui_size = 1;
 
 	xlog_copy_iovec(lv, &vecp, XLOG_REG_TYPE_RUI_FORMAT, &ruip->rui_format,
-			xfs_rui_item_sizeof(ruip));
+			xfs_rui_log_format_sizeof(ruip->rui_format.rui_nextents));
 }
 
 /*
@@ -205,16 +193,12 @@
 
 {
 	struct xfs_rui_log_item		*ruip;
-	uint				size;
 
 	ASSERT(nextents > 0);
-	if (nextents > XFS_RUI_MAX_FAST_EXTENTS) {
-		size = (uint)(sizeof(struct xfs_rui_log_item) +
-			((nextents - 1) * sizeof(struct xfs_map_extent)));
-		ruip = kmem_zalloc(size, KM_SLEEP);
-	} else {
+	if (nextents > XFS_RUI_MAX_FAST_EXTENTS)
+		ruip = kmem_zalloc(xfs_rui_log_item_sizeof(nextents), KM_SLEEP);
+	else
 		ruip = kmem_zone_zalloc(xfs_rui_zone, KM_SLEEP);
-	}
 
 	xfs_log_item_init(mp, &ruip->rui_item, XFS_LI_RUI, &xfs_rui_item_ops);
 	ruip->rui_format.rui_nextents = nextents;
@@ -239,14 +223,12 @@
 	uint				len;
 
 	src_rui_fmt = buf->i_addr;
-	len = sizeof(struct xfs_rui_log_format) +
-			(src_rui_fmt->rui_nextents - 1) *
-			sizeof(struct xfs_map_extent);
+	len = xfs_rui_log_format_sizeof(src_rui_fmt->rui_nextents);
 
 	if (buf->i_len != len)
 		return -EFSCORRUPTED;
 
-	memcpy((char *)dst_rui_fmt, (char *)src_rui_fmt, len);
+	memcpy(dst_rui_fmt, src_rui_fmt, len);
 	return 0;
 }
 
diff --git a/fs/xfs/xfs_rmap_item.h b/fs/xfs/xfs_rmap_item.h
index aefcc3a..340c968 100644
--- a/fs/xfs/xfs_rmap_item.h
+++ b/fs/xfs/xfs_rmap_item.h
@@ -70,6 +70,14 @@
 	struct xfs_rui_log_format	rui_format;
 };
 
+static inline size_t
+xfs_rui_log_item_sizeof(
+	unsigned int		nr)
+{
+	return offsetof(struct xfs_rui_log_item, rui_format) +
+			xfs_rui_log_format_sizeof(nr);
+}
+
 /*
  * This is the "rmap update done" log item.  It is used to log the fact that
  * some rmapbt updates mentioned in an earlier rui item have been performed.
diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
index c57c319..2d092f9 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -1782,9 +1782,8 @@
 	if (!xfs_rud_zone)
 		goto out_destroy_icreate_zone;
 
-	xfs_rui_zone = kmem_zone_init((sizeof(struct xfs_rui_log_item) +
-			((XFS_RUI_MAX_FAST_EXTENTS - 1) *
-				sizeof(struct xfs_map_extent))),
+	xfs_rui_zone = kmem_zone_init(
+			xfs_rui_log_item_sizeof(XFS_RUI_MAX_FAST_EXTENTS),
 			"xfs_rui_item");
 	if (!xfs_rui_zone)
 		goto out_destroy_rud_zone;
diff --git a/fs/xfs/xfs_sysfs.c b/fs/xfs/xfs_sysfs.c
index 79cfd3f..5f8d55d 100644
--- a/fs/xfs/xfs_sysfs.c
+++ b/fs/xfs/xfs_sysfs.c
@@ -393,9 +393,15 @@
 	struct kobject	*kobject,
 	char		*buf)
 {
+	int		retries;
 	struct xfs_error_cfg *cfg = to_error_cfg(kobject);
 
-	return snprintf(buf, PAGE_SIZE, "%d\n", cfg->max_retries);
+	if (cfg->retry_timeout == XFS_ERR_RETRY_FOREVER)
+		retries = -1;
+	else
+		retries = cfg->max_retries;
+
+	return snprintf(buf, PAGE_SIZE, "%d\n", retries);
 }
 
 static ssize_t
@@ -415,7 +421,10 @@
 	if (val < -1)
 		return -EINVAL;
 
-	cfg->max_retries = val;
+	if (val == -1)
+		cfg->retry_timeout = XFS_ERR_RETRY_FOREVER;
+	else
+		cfg->max_retries = val;
 	return count;
 }
 XFS_SYSFS_ATTR_RW(max_retries);
@@ -425,10 +434,15 @@
 	struct kobject	*kobject,
 	char		*buf)
 {
+	int		timeout;
 	struct xfs_error_cfg *cfg = to_error_cfg(kobject);
 
-	return snprintf(buf, PAGE_SIZE, "%ld\n",
-			jiffies_to_msecs(cfg->retry_timeout) / MSEC_PER_SEC);
+	if (cfg->retry_timeout == XFS_ERR_RETRY_FOREVER)
+		timeout = -1;
+	else
+		timeout = jiffies_to_msecs(cfg->retry_timeout) / MSEC_PER_SEC;
+
+	return snprintf(buf, PAGE_SIZE, "%d\n", timeout);
 }
 
 static ssize_t
@@ -445,11 +459,16 @@
 	if (ret)
 		return ret;
 
-	/* 1 day timeout maximum */
-	if (val < 0 || val > 86400)
+	/* 1 day timeout maximum, -1 means infinite */
+	if (val < -1 || val > 86400)
 		return -EINVAL;
 
-	cfg->retry_timeout = msecs_to_jiffies(val * MSEC_PER_SEC);
+	if (val == -1)
+		cfg->retry_timeout = XFS_ERR_RETRY_FOREVER;
+	else {
+		cfg->retry_timeout = msecs_to_jiffies(val * MSEC_PER_SEC);
+		ASSERT(msecs_to_jiffies(val * MSEC_PER_SEC) < LONG_MAX);
+	}
 	return count;
 }
 XFS_SYSFS_ATTR_RW(retry_timeout_seconds);
@@ -519,18 +538,19 @@
 static const struct xfs_error_init xfs_error_meta_init[XFS_ERR_ERRNO_MAX] = {
 	{ .name = "default",
 	  .max_retries = XFS_ERR_RETRY_FOREVER,
-	  .retry_timeout = 0,
+	  .retry_timeout = XFS_ERR_RETRY_FOREVER,
 	},
 	{ .name = "EIO",
 	  .max_retries = XFS_ERR_RETRY_FOREVER,
-	  .retry_timeout = 0,
+	  .retry_timeout = XFS_ERR_RETRY_FOREVER,
 	},
 	{ .name = "ENOSPC",
 	  .max_retries = XFS_ERR_RETRY_FOREVER,
-	  .retry_timeout = 0,
+	  .retry_timeout = XFS_ERR_RETRY_FOREVER,
 	},
 	{ .name = "ENODEV",
-	  .max_retries = 0,
+	  .max_retries = 0,	/* We can't recover from devices disappearing */
+	  .retry_timeout = 0,
 	},
 };
 
@@ -561,7 +581,10 @@
 			goto out_error;
 
 		cfg->max_retries = init[i].max_retries;
-		cfg->retry_timeout = msecs_to_jiffies(
+		if (init[i].retry_timeout == XFS_ERR_RETRY_FOREVER)
+			cfg->retry_timeout = XFS_ERR_RETRY_FOREVER;
+		else
+			cfg->retry_timeout = msecs_to_jiffies(
 					init[i].retry_timeout * MSEC_PER_SEC);
 	}
 	return 0;
diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h
index 74606cb..c6b2b1d 100644
--- a/fs/xfs/xfs_trace.h
+++ b/fs/xfs/xfs_trace.h
@@ -1570,14 +1570,15 @@
 
 TRACE_EVENT(xfs_free_extent,
 	TP_PROTO(struct xfs_mount *mp, xfs_agnumber_t agno, xfs_agblock_t agbno,
-		 xfs_extlen_t len, bool isfl, int haveleft, int haveright),
-	TP_ARGS(mp, agno, agbno, len, isfl, haveleft, haveright),
+		 xfs_extlen_t len, enum xfs_ag_resv_type resv, int haveleft,
+		 int haveright),
+	TP_ARGS(mp, agno, agbno, len, resv, haveleft, haveright),
 	TP_STRUCT__entry(
 		__field(dev_t, dev)
 		__field(xfs_agnumber_t, agno)
 		__field(xfs_agblock_t, agbno)
 		__field(xfs_extlen_t, len)
-		__field(int, isfl)
+		__field(int, resv)
 		__field(int, haveleft)
 		__field(int, haveright)
 	),
@@ -1586,16 +1587,16 @@
 		__entry->agno = agno;
 		__entry->agbno = agbno;
 		__entry->len = len;
-		__entry->isfl = isfl;
+		__entry->resv = resv;
 		__entry->haveleft = haveleft;
 		__entry->haveright = haveright;
 	),
-	TP_printk("dev %d:%d agno %u agbno %u len %u isfl %d %s",
+	TP_printk("dev %d:%d agno %u agbno %u len %u resv %d %s",
 		  MAJOR(__entry->dev), MINOR(__entry->dev),
 		  __entry->agno,
 		  __entry->agbno,
 		  __entry->len,
-		  __entry->isfl,
+		  __entry->resv,
 		  __entry->haveleft ?
 			(__entry->haveright ? "both" : "left") :
 			(__entry->haveright ? "right" : "none"))
@@ -1622,7 +1623,7 @@
 		__field(short, otype)
 		__field(char, wasdel)
 		__field(char, wasfromfl)
-		__field(char, isfl)
+		__field(int, resv)
 		__field(int, datatype)
 		__field(xfs_fsblock_t, firstblock)
 	),
@@ -1643,13 +1644,13 @@
 		__entry->otype = args->otype;
 		__entry->wasdel = args->wasdel;
 		__entry->wasfromfl = args->wasfromfl;
-		__entry->isfl = args->isfl;
+		__entry->resv = args->resv;
 		__entry->datatype = args->datatype;
 		__entry->firstblock = args->firstblock;
 	),
 	TP_printk("dev %d:%d agno %u agbno %u minlen %u maxlen %u mod %u "
 		  "prod %u minleft %u total %u alignment %u minalignslop %u "
-		  "len %u type %s otype %s wasdel %d wasfromfl %d isfl %d "
+		  "len %u type %s otype %s wasdel %d wasfromfl %d resv %d "
 		  "datatype 0x%x firstblock 0x%llx",
 		  MAJOR(__entry->dev), MINOR(__entry->dev),
 		  __entry->agno,
@@ -1667,7 +1668,7 @@
 		  __print_symbolic(__entry->otype, XFS_ALLOC_TYPES),
 		  __entry->wasdel,
 		  __entry->wasfromfl,
-		  __entry->isfl,
+		  __entry->resv,
 		  __entry->datatype,
 		  (unsigned long long)__entry->firstblock)
 )
@@ -2585,6 +2586,60 @@
 DEFINE_RMAPBT_EVENT(xfs_rmap_find_right_neighbor_result);
 DEFINE_RMAPBT_EVENT(xfs_rmap_find_left_neighbor_result);
 
+/* per-AG reservation */
+DECLARE_EVENT_CLASS(xfs_ag_resv_class,
+	TP_PROTO(struct xfs_perag *pag, enum xfs_ag_resv_type resv,
+		 xfs_extlen_t len),
+	TP_ARGS(pag, resv, len),
+	TP_STRUCT__entry(
+		__field(dev_t, dev)
+		__field(xfs_agnumber_t, agno)
+		__field(int, resv)
+		__field(xfs_extlen_t, freeblks)
+		__field(xfs_extlen_t, flcount)
+		__field(xfs_extlen_t, reserved)
+		__field(xfs_extlen_t, asked)
+		__field(xfs_extlen_t, len)
+	),
+	TP_fast_assign(
+		struct xfs_ag_resv	*r = xfs_perag_resv(pag, resv);
+
+		__entry->dev = pag->pag_mount->m_super->s_dev;
+		__entry->agno = pag->pag_agno;
+		__entry->resv = resv;
+		__entry->freeblks = pag->pagf_freeblks;
+		__entry->flcount = pag->pagf_flcount;
+		__entry->reserved = r ? r->ar_reserved : 0;
+		__entry->asked = r ? r->ar_asked : 0;
+		__entry->len = len;
+	),
+	TP_printk("dev %d:%d agno %u resv %d freeblks %u flcount %u resv %u ask %u len %u\n",
+		  MAJOR(__entry->dev), MINOR(__entry->dev),
+		  __entry->agno,
+		  __entry->resv,
+		  __entry->freeblks,
+		  __entry->flcount,
+		  __entry->reserved,
+		  __entry->asked,
+		  __entry->len)
+)
+#define DEFINE_AG_RESV_EVENT(name) \
+DEFINE_EVENT(xfs_ag_resv_class, name, \
+	TP_PROTO(struct xfs_perag *pag, enum xfs_ag_resv_type type, \
+		 xfs_extlen_t len), \
+	TP_ARGS(pag, type, len))
+
+/* per-AG reservation tracepoints */
+DEFINE_AG_RESV_EVENT(xfs_ag_resv_init);
+DEFINE_AG_RESV_EVENT(xfs_ag_resv_free);
+DEFINE_AG_RESV_EVENT(xfs_ag_resv_alloc_extent);
+DEFINE_AG_RESV_EVENT(xfs_ag_resv_free_extent);
+DEFINE_AG_RESV_EVENT(xfs_ag_resv_critical);
+DEFINE_AG_RESV_EVENT(xfs_ag_resv_needed);
+
+DEFINE_AG_ERROR_EVENT(xfs_ag_resv_free_error);
+DEFINE_AG_ERROR_EVENT(xfs_ag_resv_init_error);
+
 #endif /* _TRACE_XFS_H */
 
 #undef TRACE_INCLUDE_PATH
diff --git a/fs/xfs/xfs_trans.c b/fs/xfs/xfs_trans.c
index 5f3d33d..70f42ea 100644
--- a/fs/xfs/xfs_trans.c
+++ b/fs/xfs/xfs_trans.c
@@ -217,7 +217,7 @@
 
 undo_blocks:
 	if (blocks > 0) {
-		xfs_mod_fdblocks(tp->t_mountp, -((int64_t)blocks), rsvd);
+		xfs_mod_fdblocks(tp->t_mountp, (int64_t)blocks, rsvd);
 		tp->t_blk_res = 0;
 	}
 
@@ -318,7 +318,6 @@
 		 * in-core superblock's counter.  This should only
 		 * be applied to the on-disk superblock.
 		 */
-		ASSERT(delta < 0);
 		tp->t_res_fdblocks_delta += delta;
 		if (xfs_sb_version_haslazysbcount(&mp->m_sb))
 			flags &= ~XFS_TRANS_SB_DIRTY;
diff --git a/fs/xfs/xfs_trans_extfree.c b/fs/xfs/xfs_trans_extfree.c
index 459ddec..ab43864 100644
--- a/fs/xfs/xfs_trans_extfree.c
+++ b/fs/xfs/xfs_trans_extfree.c
@@ -79,7 +79,8 @@
 
 	trace_xfs_bmap_free_deferred(tp->t_mountp, agno, 0, agbno, ext_len);
 
-	error = xfs_free_extent(tp, start_block, ext_len, oinfo);
+	error = xfs_free_extent(tp, start_block, ext_len, oinfo,
+			XFS_AG_RESV_NONE);
 
 	/*
 	 * Mark the transaction dirty, even on error. This ensures the
diff --git a/fs/xfs/xfs_xattr.c b/fs/xfs/xfs_xattr.c
index ea62245..6290093 100644
--- a/fs/xfs/xfs_xattr.c
+++ b/fs/xfs/xfs_xattr.c
@@ -147,6 +147,7 @@
 	arraytop = context->count + prefix_len + namelen + 1;
 	if (arraytop > context->firstu) {
 		context->count = -1;	/* insufficient space */
+		context->seen_enough = 1;
 		return 0;
 	}
 	offset = (char *)context->alist + context->count;
diff --git a/include/linux/dax.h b/include/linux/dax.h
index 9c6dc77..add6c4b 100644
--- a/include/linux/dax.h
+++ b/include/linux/dax.h
@@ -6,13 +6,19 @@
 #include <linux/radix-tree.h>
 #include <asm/pgtable.h>
 
+struct iomap_ops;
+
 /* We use lowest available exceptional entry bit for locking */
 #define RADIX_DAX_ENTRY_LOCK (1 << RADIX_TREE_EXCEPTIONAL_SHIFT)
 
+ssize_t iomap_dax_rw(struct kiocb *iocb, struct iov_iter *iter,
+		struct iomap_ops *ops);
 ssize_t dax_do_io(struct kiocb *, struct inode *, struct iov_iter *,
 		  get_block_t, dio_iodone_t, int flags);
 int dax_zero_page_range(struct inode *, loff_t from, unsigned len, get_block_t);
 int dax_truncate_page(struct inode *, loff_t from, get_block_t);
+int iomap_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
+			struct iomap_ops *ops);
 int dax_fault(struct vm_area_struct *, struct vm_fault *, get_block_t);
 int dax_delete_mapping_entry(struct address_space *mapping, pgoff_t index);
 void dax_wake_mapping_entry_waiter(struct address_space *mapping,
diff --git a/include/linux/iomap.h b/include/linux/iomap.h
index 3d70ece..e63e288 100644
--- a/include/linux/iomap.h
+++ b/include/linux/iomap.h
@@ -22,6 +22,8 @@
  * Flags for iomap mappings:
  */
 #define IOMAP_F_MERGED	0x01	/* contains multiple blocks/extents */
+#define IOMAP_F_SHARED	0x02	/* block shared with another file */
+#define IOMAP_F_NEW	0x04	/* blocks have been newly allocated */
 
 /*
  * Magic value for blkno:
@@ -64,6 +66,8 @@
 
 ssize_t iomap_file_buffered_write(struct kiocb *iocb, struct iov_iter *from,
 		struct iomap_ops *ops);
+int iomap_file_dirty(struct inode *inode, loff_t pos, loff_t len,
+		struct iomap_ops *ops);
 int iomap_zero_range(struct inode *inode, loff_t pos, loff_t len,
 		bool *did_zero, struct iomap_ops *ops);
 int iomap_truncate_page(struct inode *inode, loff_t pos, bool *did_zero,
diff --git a/mm/filemap.c b/mm/filemap.c
index 8a287df..2f1175e 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1910,16 +1910,18 @@
 	if (iocb->ki_flags & IOCB_DIRECT) {
 		struct address_space *mapping = file->f_mapping;
 		struct inode *inode = mapping->host;
+		struct iov_iter data = *iter;
 		loff_t size;
 
 		size = i_size_read(inode);
 		retval = filemap_write_and_wait_range(mapping, iocb->ki_pos,
 					iocb->ki_pos + count - 1);
-		if (!retval) {
-			struct iov_iter data = *iter;
-			retval = mapping->a_ops->direct_IO(iocb, &data);
-		}
+		if (retval < 0)
+			goto out;
 
+		file_accessed(file);
+
+		retval = mapping->a_ops->direct_IO(iocb, &data);
 		if (retval > 0) {
 			iocb->ki_pos += retval;
 			iov_iter_advance(iter, retval);
@@ -1935,10 +1937,8 @@
 		 * DAX files, so don't bother trying.
 		 */
 		if (retval < 0 || !iov_iter_count(iter) || iocb->ki_pos >= size ||
-		    IS_DAX(inode)) {
-			file_accessed(file);
+		    IS_DAX(inode))
 			goto out;
-		}
 	}
 
 	retval = do_generic_file_read(file, &iocb->ki_pos, iter, retval);