afs: Implement shared-writeable mmap
Implement shared-writeable mmap for AFS.
Signed-off-by: David Howells <dhowells@redhat.com>
diff --git a/fs/afs/file.c b/fs/afs/file.c
index fc0896c..0d89c8a 100644
--- a/fs/afs/file.c
+++ b/fs/afs/file.c
@@ -19,6 +19,7 @@
#include <linux/task_io_accounting_ops.h>
#include "internal.h"
+static int afs_file_mmap(struct file *file, struct vm_area_struct *vma);
static int afs_readpage(struct file *file, struct page *page);
static void afs_invalidatepage(struct page *page, unsigned int offset,
unsigned int length);
@@ -34,7 +35,7 @@ const struct file_operations afs_file_operations = {
.llseek = generic_file_llseek,
.read_iter = generic_file_read_iter,
.write_iter = afs_file_write,
- .mmap = generic_file_readonly_mmap,
+ .mmap = afs_file_mmap,
.splice_read = generic_file_splice_read,
.fsync = afs_fsync,
.lock = afs_lock,
@@ -60,6 +61,12 @@ const struct address_space_operations afs_fs_aops = {
.writepages = afs_writepages,
};
+static const struct vm_operations_struct afs_vm_ops = {
+ .fault = filemap_fault,
+ .map_pages = filemap_map_pages,
+ .page_mkwrite = afs_page_mkwrite,
+};
+
/*
* open an AFS file or directory and attach a key to it
*/
@@ -543,3 +550,16 @@ static int afs_releasepage(struct page *page, gfp_t gfp_flags)
_leave(" = %d", cleared);
return cleared;
}
+
+/*
+ * Handle setting up a memory mapping on an AFS file.
+ */
+static int afs_file_mmap(struct file *file, struct vm_area_struct *vma)
+{
+ int ret;
+
+ ret = generic_file_mmap(file, vma);
+ if (ret == 0)
+ vma->vm_ops = &afs_vm_ops;
+ return ret;
+}
diff --git a/fs/afs/internal.h b/fs/afs/internal.h
index 0de1f1b..2158f99 100644
--- a/fs/afs/internal.h
+++ b/fs/afs/internal.h
@@ -734,6 +734,8 @@ extern int afs_writeback_all(struct afs_vnode *);
extern int afs_flush(struct file *, fl_owner_t);
extern int afs_fsync(struct file *, loff_t, loff_t, int);
extern int afs_launder_page(struct page *);
+extern int afs_page_mkwrite(struct vm_fault *);
+
/*****************************************************************************/
/*
diff --git a/fs/afs/write.c b/fs/afs/write.c
index b349151..c8ac34b 100644
--- a/fs/afs/write.c
+++ b/fs/afs/write.c
@@ -1033,21 +1033,57 @@ int afs_flush(struct file *file, fl_owner_t id)
* notification that a previously read-only page is about to become writable
* - if it returns an error, the caller will deliver a bus error signal
*/
-int afs_page_mkwrite(struct vm_area_struct *vma, struct page *page)
+int afs_page_mkwrite(struct vm_fault *vmf)
{
- struct afs_vnode *vnode = AFS_FS_I(vma->vm_file->f_mapping->host);
+ struct file *file = vmf->vma->vm_file;
+ struct inode *inode = file_inode(file);
+ struct afs_vnode *vnode = AFS_FS_I(inode);
+ struct afs_writeback *candidate;
+ struct key *key = file->private_data;
+ int ret, vret;
_enter("{{%x:%u}},{%lx}",
- vnode->fid.vid, vnode->fid.vnode, page->index);
+ vnode->fid.vid, vnode->fid.vnode, vmf->page->index);
+ candidate = afs_alloc_writeback(vnode, key, vmf->page->index, 0, PAGE_SIZE);
+ if (!candidate)
+ return VM_FAULT_OOM;
+
+ sb_start_pagefault(inode->i_sb);
+
+retry:
/* wait for the page to be written to the cache before we allow it to
* be modified */
#ifdef CONFIG_AFS_FSCACHE
- fscache_wait_on_page_write(vnode->cache, page);
+ fscache_wait_on_page_write(vnode->cache, vmf->page);
#endif
- _leave(" = 0");
- return 0;
+ /* TODO: Get the key from vma->vm_file, flush any overlapping
+ * contradictory writeback record, set up new a writeback record if
+ * needed and remove the R/O check from afs_file_mmap().
+ *
+ * The code can probably be common with much of afs_write_begin().
+ */
+ lock_page(vmf->page);
+ vret = VM_FAULT_LOCKED;
+
+ ret = afs_add_writeback(vnode, candidate, vmf->page);
+ switch (ret) {
+ case 0:
+ break;
+ case -EAGAIN:
+ goto retry;
+ case -ENOMEM:
+ vret |= VM_FAULT_OOM;
+ break;
+ default:
+ vret |= VM_FAULT_SIGBUS;
+ break;
+ }
+
+ sb_end_pagefault(inode->i_sb);
+ _leave(" = %d", vret);
+ return vret;
}
/*
