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Subject[PATCH 1/2] btrfs: don't mess with i_nlink of unlocked inode in rename()
old_inode is not locked; it's not safe to play with its link
count. Instead of bumping it and calling btrfs_unlink_inode(),
add a variant of the latter that does not do btrfs_drop_nlink()/
btrfs_update_inode(), call it instead of btrfs_inc_nlink()/
btrfs_unlink_inode() and do btrfs_update_inode() ourselves.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
fs/btrfs/inode.c | 36 +++++++++++++++++++++++++-----------
1 files changed, 25 insertions(+), 11 deletions(-)

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 0efdb65..099d64c 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -2634,10 +2634,10 @@ failed:
* recovery code. It remove a link in a directory with a given name, and
* also drops the back refs in the inode to the directory
*/
-int btrfs_unlink_inode(struct btrfs_trans_handle *trans,
- struct btrfs_root *root,
- struct inode *dir, struct inode *inode,
- const char *name, int name_len)
+static int __btrfs_unlink_inode(struct btrfs_trans_handle *trans,
+ struct btrfs_root *root,
+ struct inode *dir, struct inode *inode,
+ const char *name, int name_len)
{
struct btrfs_path *path;
int ret = 0;
@@ -2709,12 +2709,25 @@ err:
btrfs_i_size_write(dir, dir->i_size - name_len * 2);
inode->i_ctime = dir->i_mtime = dir->i_ctime = CURRENT_TIME;
btrfs_update_inode(trans, root, dir);
- btrfs_drop_nlink(inode);
- ret = btrfs_update_inode(trans, root, inode);
out:
return ret;
}

+int btrfs_unlink_inode(struct btrfs_trans_handle *trans,
+ struct btrfs_root *root,
+ struct inode *dir, struct inode *inode,
+ const char *name, int name_len)
+{
+ int ret;
+ ret = __btrfs_unlink_inode(trans, root, dir, inode, name, name_len);
+ if (!ret) {
+ btrfs_drop_nlink(inode);
+ ret = btrfs_update_inode(trans, root, inode);
+ }
+ return ret;
+}
+
+
/* helper to check if there is any shared block in the path */
static int check_path_shared(struct btrfs_root *root,
struct btrfs_path *path)
@@ -6908,11 +6921,12 @@ static int btrfs_rename(struct inode *old_dir, struct dentry *old_dentry,
old_dentry->d_name.name,
old_dentry->d_name.len);
} else {
- btrfs_inc_nlink(old_dentry->d_inode);
- ret = btrfs_unlink_inode(trans, root, old_dir,
- old_dentry->d_inode,
- old_dentry->d_name.name,
- old_dentry->d_name.len);
+ ret = __btrfs_unlink_inode(trans, root, old_dir,
+ old_dentry->d_inode,
+ old_dentry->d_name.name,
+ old_dentry->d_name.len);
+ if (!ret)
+ ret = btrfs_update_inode(trans, root, old_inode);
}
BUG_ON(ret);

--
1.7.2.5


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