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author | Anand Jain <anand.jain@oracle.com> | 2021-04-30 19:59:51 +0800 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-06-10 13:37:15 +0200 |
commit | 0450af01ae7e7df5786833255a50e2502df80a95 (patch) | |
tree | b66bf9a223d166e073306437b36f43fe925a84b4 | |
parent | mm/filemap: fix storing to a THP shadow entry (diff) | |
download | wireguard-linux-0450af01ae7e7df5786833255a50e2502df80a95.tar.xz wireguard-linux-0450af01ae7e7df5786833255a50e2502df80a95.zip |
btrfs: fix unmountable seed device after fstrim
commit 5e753a817b2d5991dfe8a801b7b1e8e79a1c5a20 upstream.
The following test case reproduces an issue of wrongly freeing in-use
blocks on the readonly seed device when fstrim is called on the rw sprout
device. As shown below.
Create a seed device and add a sprout device to it:
$ mkfs.btrfs -fq -dsingle -msingle /dev/loop0
$ btrfstune -S 1 /dev/loop0
$ mount /dev/loop0 /btrfs
$ btrfs dev add -f /dev/loop1 /btrfs
BTRFS info (device loop0): relocating block group 290455552 flags system
BTRFS info (device loop0): relocating block group 1048576 flags system
BTRFS info (device loop0): disk added /dev/loop1
$ umount /btrfs
Mount the sprout device and run fstrim:
$ mount /dev/loop1 /btrfs
$ fstrim /btrfs
$ umount /btrfs
Now try to mount the seed device, and it fails:
$ mount /dev/loop0 /btrfs
mount: /btrfs: wrong fs type, bad option, bad superblock on /dev/loop0, missing codepage or helper program, or other error.
Block 5292032 is missing on the readonly seed device:
$ dmesg -kt | tail
<snip>
BTRFS error (device loop0): bad tree block start, want 5292032 have 0
BTRFS warning (device loop0): couldn't read-tree root
BTRFS error (device loop0): open_ctree failed
>From the dump-tree of the seed device (taken before the fstrim). Block
5292032 belonged to the block group starting at 5242880:
$ btrfs inspect dump-tree -e /dev/loop0 | grep -A1 BLOCK_GROUP
<snip>
item 3 key (5242880 BLOCK_GROUP_ITEM 8388608) itemoff 16169 itemsize 24
block group used 114688 chunk_objectid 256 flags METADATA
<snip>
>From the dump-tree of the sprout device (taken before the fstrim).
fstrim used block-group 5242880 to find the related free space to free:
$ btrfs inspect dump-tree -e /dev/loop1 | grep -A1 BLOCK_GROUP
<snip>
item 1 key (5242880 BLOCK_GROUP_ITEM 8388608) itemoff 16226 itemsize 24
block group used 32768 chunk_objectid 256 flags METADATA
<snip>
BPF kernel tracing the fstrim command finds the missing block 5292032
within the range of the discarded blocks as below:
kprobe:btrfs_discard_extent {
printf("freeing start %llu end %llu num_bytes %llu:\n",
arg1, arg1+arg2, arg2);
}
freeing start 5259264 end 5406720 num_bytes 147456
<snip>
Fix this by avoiding the discard command to the readonly seed device.
Reported-by: Chris Murphy <lists@colorremedies.com>
CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r-- | fs/btrfs/extent-tree.c | 10 |
1 files changed, 7 insertions, 3 deletions
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index 22622ea532cd..832b40293907 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -1338,16 +1338,20 @@ int btrfs_discard_extent(struct btrfs_fs_info *fs_info, u64 bytenr, for (i = 0; i < bbio->num_stripes; i++, stripe++) { u64 bytes; struct request_queue *req_q; + struct btrfs_device *device = stripe->dev; - if (!stripe->dev->bdev) { + if (!device->bdev) { ASSERT(btrfs_test_opt(fs_info, DEGRADED)); continue; } - req_q = bdev_get_queue(stripe->dev->bdev); + req_q = bdev_get_queue(device->bdev); if (!blk_queue_discard(req_q)) continue; - ret = btrfs_issue_discard(stripe->dev->bdev, + if (!test_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state)) + continue; + + ret = btrfs_issue_discard(device->bdev, stripe->physical, stripe->length, &bytes); |