The patch below does not apply to the 4.9-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From d8ac76cdd1755b21e8c008c28d0b7251c0b14986 Mon Sep 17 00:00:00 2001
From: Filipe Manana fdmanana@suse.com Date: Wed, 9 Jun 2021 11:25:03 +0100 Subject: [PATCH] btrfs: send: fix invalid path for unlink operations after parent orphanization
During an incremental send operation, when processing the new references for the current inode, we might send an unlink operation for another inode that has a conflicting path and has more than one hard link. However this path was computed and cached before we processed previous new references for the current inode. We may have orphanized a directory of that path while processing a previous new reference, in which case the path will be invalid and cause the receiver process to fail.
The following reproducer triggers the problem and explains how/why it happens in its comments:
$ cat test-send-unlink.sh #!/bin/bash
DEV=/dev/sdi MNT=/mnt/sdi
mkfs.btrfs -f $DEV >/dev/null mount $DEV $MNT
# Create our test files and directory. Inode 259 (file3) has two hard # links. touch $MNT/file1 touch $MNT/file2 touch $MNT/file3
mkdir $MNT/A ln $MNT/file3 $MNT/A/hard_link
# Filesystem looks like: # # . (ino 256) # |----- file1 (ino 257) # |----- file2 (ino 258) # |----- file3 (ino 259) # |----- A/ (ino 260) # |---- hard_link (ino 259) #
# Now create the base snapshot, which is going to be the parent snapshot # for a later incremental send. btrfs subvolume snapshot -r $MNT $MNT/snap1 btrfs send -f /tmp/snap1.send $MNT/snap1
# Move inode 257 into directory inode 260. This results in computing the # path for inode 260 as "/A" and caching it. mv $MNT/file1 $MNT/A/file1
# Move inode 258 (file2) into directory inode 260, with a name of # "hard_link", moving first inode 259 away since it currently has that # location and name. mv $MNT/A/hard_link $MNT/tmp mv $MNT/file2 $MNT/A/hard_link
# Now rename inode 260 to something else (B for example) and then create # a hard link for inode 258 that has the old name and location of inode # 260 ("/A"). mv $MNT/A $MNT/B ln $MNT/B/hard_link $MNT/A
# Filesystem now looks like: # # . (ino 256) # |----- tmp (ino 259) # |----- file3 (ino 259) # |----- B/ (ino 260) # | |---- file1 (ino 257) # | |---- hard_link (ino 258) # | # |----- A (ino 258)
# Create another snapshot of our subvolume and use it for an incremental # send. btrfs subvolume snapshot -r $MNT $MNT/snap2 btrfs send -f /tmp/snap2.send -p $MNT/snap1 $MNT/snap2
# Now unmount the filesystem, create a new one, mount it and try to # apply both send streams to recreate both snapshots. umount $DEV
mkfs.btrfs -f $DEV >/dev/null
mount $DEV $MNT
# First add the first snapshot to the new filesystem by applying the # first send stream. btrfs receive -f /tmp/snap1.send $MNT
# The incremental receive operation below used to fail with the # following error: # # ERROR: unlink A/hard_link failed: No such file or directory # # This is because when send is processing inode 257, it generates the # path for inode 260 as "/A", since that inode is its parent in the send # snapshot, and caches that path. # # Later when processing inode 258, it first processes its new reference # that has the path of "/A", which results in orphanizing inode 260 # because there is a a path collision. This results in issuing a rename # operation from "/A" to "/o260-6-0". # # Finally when processing the new reference "B/hard_link" for inode 258, # it notices that it collides with inode 259 (not yet processed, because # it has a higher inode number), since that inode has the name # "hard_link" under the directory inode 260. It also checks that inode # 259 has two hardlinks, so it decides to issue a unlink operation for # the name "hard_link" for inode 259. However the path passed to the # unlink operation is "/A/hard_link", which is incorrect since currently # "/A" does not exists, due to the orphanization of inode 260 mentioned # before. The path is incorrect because it was computed and cached # before the orphanization. This results in the receiver to fail with # the above error. btrfs receive -f /tmp/snap2.send $MNT
umount $MNT
When running the test, it fails like this:
$ ./test-send-unlink.sh Create a readonly snapshot of '/mnt/sdi' in '/mnt/sdi/snap1' At subvol /mnt/sdi/snap1 Create a readonly snapshot of '/mnt/sdi' in '/mnt/sdi/snap2' At subvol /mnt/sdi/snap2 At subvol snap1 At snapshot snap2 ERROR: unlink A/hard_link failed: No such file or directory
Fix this by recomputing a path before issuing an unlink operation when processing the new references for the current inode if we previously have orphanized a directory.
A test case for fstests will follow soon.
CC: stable@vger.kernel.org # 4.4+ Signed-off-by: Filipe Manana fdmanana@suse.com Signed-off-by: David Sterba dsterba@suse.com
diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c index bd69db72acc5..a2b3c594379d 100644 --- a/fs/btrfs/send.c +++ b/fs/btrfs/send.c @@ -4064,6 +4064,17 @@ static int process_recorded_refs(struct send_ctx *sctx, int *pending_move) if (ret < 0) goto out; } else { + /* + * If we previously orphanized a directory that + * collided with a new reference that we already + * processed, recompute the current path because + * that directory may be part of the path. + */ + if (orphanized_dir) { + ret = refresh_ref_path(sctx, cur); + if (ret < 0) + goto out; + } ret = send_unlink(sctx, cur->full_path); if (ret < 0) goto out;