From 7b119a8b8998f17abd6caf928dee5bf203eef8c5 Mon Sep 17 00:00:00 2001 From: Filipe Manana Date: Sun, 16 Mar 2014 20:37:26 +0000 Subject: Btrfs: fix incremental send's decision to delay a dir move/rename It's possible to change the parent/child relationship between directories in such a way that if a child directory has a higher inode number than its parent, it doesn't necessarily means the child rename/move operation can be performed immediately. The parent migth have its own rename/move operation delayed, therefore in this case the child needs to have its rename/move operation delayed too, and be performed after its new parent's rename/move. Steps to reproduce the issue: $ umount /mnt $ mkfs.btrfs -f /dev/sdd $ mount /dev/sdd /mnt $ mkdir /mnt/A $ mkdir /mnt/B $ mkdir /mnt/C $ mv /mnt/C /mnt/A $ mv /mnt/B /mnt/A/C $ mkdir /mnt/A/C/D $ btrfs subvolume snapshot -r /mnt /mnt/snap1 $ btrfs send /mnt/snap1 -f /tmp/base.send $ mv /mnt/A/C/D /mnt/A/D2 $ mv /mnt/A/C/B /mnt/A/D2/B2 $ mv /mnt/A/C /mnt/A/D2/B2/C2 $ btrfs subvolume snapshot -r /mnt /mnt/snap2 $ btrfs send -p /mnt/snap1 /mnt/snap2 -f /tmp/incremental.send The incremental send caused the kernel code to enter an infinite loop when building the path string for directory C after its references are processed. The necessary conditions here are that C has an inode number higher than both A and B, and B as an higher inode number higher than A, and D has the highest inode number, that is: inode_number(A) < inode_number(B) < inode_number(C) < inode_number(D) The same issue could happen if after the first snapshot there's any number of intermediary parent directories between A2 and B2, and between B2 and C2. A test case for xfstests follows, covering this simple case and more advanced ones, with files and hard links created inside the directories. Signed-off-by: Filipe David Borba Manana Signed-off-by: Chris Mason --- fs/btrfs/send.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'fs/btrfs/send.c') diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c index 92d4ae8..f164724 100644 --- a/fs/btrfs/send.c +++ b/fs/btrfs/send.c @@ -3184,12 +3184,12 @@ static int wait_for_parent_move(struct send_ctx *sctx, struct fs_path *path_after = NULL; int len1, len2; - if (parent_ref->dir <= sctx->cur_ino) - return 0; - if (is_waiting_for_move(sctx, ino)) return 1; + if (parent_ref->dir <= sctx->cur_ino) + return 0; + ret = get_inode_info(sctx->parent_root, ino, NULL, &old_gen, NULL, NULL, NULL, NULL); if (ret == -ENOENT) -- cgit v1.1