release/5.2.37/btrfs-rework-arguments-of-btrfs_unlink_subvol.patch

From 5bd2acd99fb3e34c79075cc673f2b47871c541a1 Mon Sep 17 00:00:00 2001
From: Josef Bacik <josef@toxicpanda.com>
Date: Wed, 18 Dec 2019 17:20:27 -0500
Subject: [PATCH] btrfs: rework arguments of btrfs_unlink_subvol

commit 045d3967b6920b663fc010ad414ade1b24143bd1 upstream.

btrfs_unlink_subvol takes the name of the dentry and the root objectid
based on what kind of inode this is, either a real subvolume link or a
empty one that we inherited as a snapshot.  We need to fix how we unlink
in the case for BTRFS_EMPTY_SUBVOL_DIR_OBJECTID in the future, so rework
btrfs_unlink_subvol to just take the dentry and handle getting the right
objectid given the type of inode this is.  There is no functional change
here, simply pushing the work into btrfs_unlink_subvol() proper.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 25515b097125..eed3087d5f3e 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -4142,18 +4142,30 @@ static int btrfs_unlink(struct inode *dir, struct dentry *dentry)
 }
 
 static int btrfs_unlink_subvol(struct btrfs_trans_handle *trans,
-			       struct inode *dir, u64 objectid,
-			       const char *name, int name_len)
+			       struct inode *dir, struct dentry *dentry)
 {
 	struct btrfs_root *root = BTRFS_I(dir)->root;
+	struct btrfs_inode *inode = BTRFS_I(d_inode(dentry));
 	struct btrfs_path *path;
 	struct extent_buffer *leaf;
 	struct btrfs_dir_item *di;
 	struct btrfs_key key;
+	const char *name = dentry->d_name.name;
+	int name_len = dentry->d_name.len;
 	u64 index;
 	int ret;
+	u64 objectid;
 	u64 dir_ino = btrfs_ino(BTRFS_I(dir));
 
+	if (btrfs_ino(inode) == BTRFS_FIRST_FREE_OBJECTID) {
+		objectid = inode->root->root_key.objectid;
+	} else if (btrfs_ino(inode) == BTRFS_EMPTY_SUBVOL_DIR_OBJECTID) {
+		objectid = inode->location.objectid;
+	} else {
+		WARN_ON(1);
+		return -EINVAL;
+	}
+
 	path = btrfs_alloc_path();
 	if (!path)
 		return -ENOMEM;
@@ -4391,8 +4403,7 @@ int btrfs_delete_subvolume(struct inode *dir, struct dentry *dentry)
 
 	btrfs_record_snapshot_destroy(trans, BTRFS_I(dir));
 
-	ret = btrfs_unlink_subvol(trans, dir, dest->root_key.objectid,
-				  dentry->d_name.name, dentry->d_name.len);
+	ret = btrfs_unlink_subvol(trans, dir, dentry);
 	if (ret) {
 		err = ret;
 		btrfs_abort_transaction(trans, ret);
@@ -4487,10 +4498,7 @@ static int btrfs_rmdir(struct inode *dir, struct dentry *dentry)
 		return PTR_ERR(trans);
 
 	if (unlikely(btrfs_ino(BTRFS_I(inode)) == BTRFS_EMPTY_SUBVOL_DIR_OBJECTID)) {
-		err = btrfs_unlink_subvol(trans, dir,
-					  BTRFS_I(inode)->location.objectid,
-					  dentry->d_name.name,
-					  dentry->d_name.len);
+		err = btrfs_unlink_subvol(trans, dir, dentry);
 		goto out;
 	}
 
@@ -9479,7 +9487,6 @@ static int btrfs_rename_exchange(struct inode *old_dir,
 	u64 new_ino = btrfs_ino(BTRFS_I(new_inode));
 	u64 old_idx = 0;
 	u64 new_idx = 0;
-	u64 root_objectid;
 	int ret;
 	bool root_log_pinned = false;
 	bool dest_log_pinned = false;
@@ -9585,10 +9592,7 @@ static int btrfs_rename_exchange(struct inode *old_dir,
 
 	/* src is a subvolume */
 	if (old_ino == BTRFS_FIRST_FREE_OBJECTID) {
-		root_objectid = BTRFS_I(old_inode)->root->root_key.objectid;
-		ret = btrfs_unlink_subvol(trans, old_dir, root_objectid,
-					  old_dentry->d_name.name,
-					  old_dentry->d_name.len);
+		ret = btrfs_unlink_subvol(trans, old_dir, old_dentry);
 	} else { /* src is an inode */
 		ret = __btrfs_unlink_inode(trans, root, BTRFS_I(old_dir),
 					   BTRFS_I(old_dentry->d_inode),
@@ -9604,10 +9608,7 @@ static int btrfs_rename_exchange(struct inode *old_dir,
 
 	/* dest is a subvolume */
 	if (new_ino == BTRFS_FIRST_FREE_OBJECTID) {
-		root_objectid = BTRFS_I(new_inode)->root->root_key.objectid;
-		ret = btrfs_unlink_subvol(trans, new_dir, root_objectid,
-					  new_dentry->d_name.name,
-					  new_dentry->d_name.len);
+		ret = btrfs_unlink_subvol(trans, new_dir, new_dentry);
 	} else { /* dest is an inode */
 		ret = __btrfs_unlink_inode(trans, dest, BTRFS_I(new_dir),
 					   BTRFS_I(new_dentry->d_inode),
@@ -9805,7 +9806,6 @@ static int btrfs_rename(struct inode *old_dir, struct dentry *old_dentry,
 	struct inode *new_inode = d_inode(new_dentry);
 	struct inode *old_inode = d_inode(old_dentry);
 	u64 index = 0;
-	u64 root_objectid;
 	int ret;
 	u64 old_ino = btrfs_ino(BTRFS_I(old_inode));
 	bool log_pinned = false;
@@ -9913,10 +9913,7 @@ static int btrfs_rename(struct inode *old_dir, struct dentry *old_dentry,
 				BTRFS_I(old_inode), 1);
 
 	if (unlikely(old_ino == BTRFS_FIRST_FREE_OBJECTID)) {
-		root_objectid = BTRFS_I(old_inode)->root->root_key.objectid;
-		ret = btrfs_unlink_subvol(trans, old_dir, root_objectid,
-					old_dentry->d_name.name,
-					old_dentry->d_name.len);
+		ret = btrfs_unlink_subvol(trans, old_dir, old_dentry);
 	} else {
 		ret = __btrfs_unlink_inode(trans, root, BTRFS_I(old_dir),
 					BTRFS_I(d_inode(old_dentry)),
@@ -9935,10 +9932,7 @@ static int btrfs_rename(struct inode *old_dir, struct dentry *old_dentry,
 		new_inode->i_ctime = current_time(new_inode);
 		if (unlikely(btrfs_ino(BTRFS_I(new_inode)) ==
 			     BTRFS_EMPTY_SUBVOL_DIR_OBJECTID)) {
-			root_objectid = BTRFS_I(new_inode)->location.objectid;
-			ret = btrfs_unlink_subvol(trans, new_dir, root_objectid,
-						new_dentry->d_name.name,
-						new_dentry->d_name.len);
+			ret = btrfs_unlink_subvol(trans, new_dir, new_dentry);
 			BUG_ON(new_inode->i_nlink == 0);
 		} else {
 			ret = btrfs_unlink_inode(trans, dest, BTRFS_I(new_dir),
-- 
2.7.4