3.16.60-rc1 review patch. If anyone has any objections, please let me know.
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From: Filipe Manana fdmanana@suse.com
commit d50866d00fb39fcf72307001763ee9cc92625a43 upstream.
When we are creating a symlink we might fail with an error after we created its inode and added the corresponding directory indexes to its parent inode. In this case we end up never removing the directory indexes because the inode eviction handler, called for our symlink inode on the final iput(), only removes items associated with the symlink inode and not with the parent inode.
Example:
$ mkfs.btrfs -f /dev/sdi $ mount /dev/sdi /mnt $ touch /mnt/foo $ ln -s /mnt/foo /mnt/bar ln: failed to create symbolic link ‘bar’: Cannot allocate memory $ umount /mnt $ btrfsck /dev/sdi Checking filesystem on /dev/sdi UUID: d5acb5ba-31bd-42da-b456-89dca2e716e1 checking extents checking free space cache checking fs roots root 5 inode 258 errors 2001, no inode item, link count wrong unresolved ref dir 256 index 3 namelen 3 name bar filetype 7 errors 4, no inode ref found 131073 bytes used err is 1 total csum bytes: 0 total tree bytes: 131072 total fs tree bytes: 32768 total extent tree bytes: 16384 btree space waste bytes: 124305 file data blocks allocated: 262144 referenced 262144 btrfs-progs v4.2.3
So fix this by adding the directory index entries as the very last step of symlink creation.
Signed-off-by: Filipe Manana fdmanana@suse.com Signed-off-by: Ben Hutchings ben@decadent.org.uk --- fs/btrfs/inode.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-)
--- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -8877,10 +8877,6 @@ static int btrfs_symlink(struct inode *d if (err) goto out_unlock_inode;
- err = btrfs_add_nondir(trans, dir, dentry, inode, 0, index); - if (err) - goto out_unlock_inode; - path = btrfs_alloc_path(); if (!path) { err = -ENOMEM; @@ -8918,6 +8914,13 @@ static int btrfs_symlink(struct inode *d inode_set_bytes(inode, name_len); btrfs_i_size_write(inode, name_len); err = btrfs_update_inode(trans, root, inode); + /* + * Last step, add directory indexes for our symlink inode. This is the + * last step to avoid extra cleanup of these indexes if an error happens + * elsewhere above. + */ + if (!err) + err = btrfs_add_nondir(trans, dir, dentry, inode, 0, index); if (err) { drop_inode = 1; goto out_unlock_inode;