5.4-stable review patch. If anyone has any objections, please let me know.
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From: Filipe Manana fdmanana@suse.com
[ Upstream commit c466e33e729a0ee017d10d919cba18f503853c60 ]
In case the removed directory had a snapshot that was deleted, we are propagating its inode's last_unlink_trans to the parent directory after we removed the entry from the parent directory. This leaves a small race window where someone can log the parent directory after we removed the entry and before we updated last_unlink_trans, and as a result if we ever try to replay such a log tree, we will fail since we will attempt to remove a snapshot during log replay, which is currently not possible and results in the log replay (and mount) to fail. This is the type of failure described in commit 1ec9a1ae1e30 ("Btrfs: fix unreplayable log after snapshot delete + parent dir fsync").
So fix this by propagating the last_unlink_trans to the parent directory before we remove the entry from it.
Fixes: 44f714dae50a ("Btrfs: improve performance on fsync against new inode after rename/unlink") Reviewed-by: Johannes Thumshirn johannes.thumshirn@wdc.com Signed-off-by: Filipe Manana fdmanana@suse.com Signed-off-by: David Sterba dsterba@suse.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/btrfs/inode.c | 36 ++++++++++++++++++------------------ 1 file changed, 18 insertions(+), 18 deletions(-)
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 004894e6dd23b..8f92f998dc37b 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -4747,7 +4747,6 @@ static int btrfs_rmdir(struct inode *dir, struct dentry *dentry) int err = 0; struct btrfs_root *root = BTRFS_I(dir)->root; struct btrfs_trans_handle *trans; - u64 last_unlink_trans;
if (inode->i_size > BTRFS_EMPTY_DIR_SIZE) return -ENOTEMPTY; @@ -4758,6 +4757,23 @@ static int btrfs_rmdir(struct inode *dir, struct dentry *dentry) if (IS_ERR(trans)) return PTR_ERR(trans);
+ /* + * Propagate the last_unlink_trans value of the deleted dir to its + * parent directory. This is to prevent an unrecoverable log tree in the + * case we do something like this: + * 1) create dir foo + * 2) create snapshot under dir foo + * 3) delete the snapshot + * 4) rmdir foo + * 5) mkdir foo + * 6) fsync foo or some file inside foo + * + * This is because we can't unlink other roots when replaying the dir + * deletes for directory foo. + */ + if (BTRFS_I(inode)->last_unlink_trans >= trans->transid) + BTRFS_I(dir)->last_unlink_trans = BTRFS_I(inode)->last_unlink_trans; + if (unlikely(btrfs_ino(BTRFS_I(inode)) == BTRFS_EMPTY_SUBVOL_DIR_OBJECTID)) { err = btrfs_unlink_subvol(trans, dir, dentry); goto out; @@ -4767,28 +4783,12 @@ static int btrfs_rmdir(struct inode *dir, struct dentry *dentry) if (err) goto out;
- last_unlink_trans = BTRFS_I(inode)->last_unlink_trans; - /* now the directory is empty */ err = btrfs_unlink_inode(trans, root, BTRFS_I(dir), BTRFS_I(d_inode(dentry)), dentry->d_name.name, dentry->d_name.len); - if (!err) { + if (!err) btrfs_i_size_write(BTRFS_I(inode), 0); - /* - * Propagate the last_unlink_trans value of the deleted dir to - * its parent directory. This is to prevent an unrecoverable - * log tree in the case we do something like this: - * 1) create dir foo - * 2) create snapshot under dir foo - * 3) delete the snapshot - * 4) rmdir foo - * 5) mkdir foo - * 6) fsync foo or some file inside foo - */ - if (last_unlink_trans >= trans->transid) - BTRFS_I(dir)->last_unlink_trans = last_unlink_trans; - } out: btrfs_end_transaction(trans); btrfs_btree_balance_dirty(root->fs_info);