From: Filipe Manana fdmanana@suse.com
commit 4c8f353272dd1262013873990c0fafd0e3c8f274 upstream.
We use a device's allocation state tree to track ranges in a device used for allocated chunks, and we set ranges in this tree when allocating a new chunk. However after a device replace operation, we were not setting the allocated ranges in the new device's allocation state tree, so that tree is empty after a device replace.
This means that a fitrim operation after a device replace will trim the device ranges that have allocated chunks and extents, as we trim every range for which there is not a range marked in the device's allocation state tree. It is also important during chunk allocation, since the device's allocation state is used to determine if a range is already allocated when allocating a new chunk.
This is trivial to reproduce and the following script triggers the bug:
$ cat reproducer.sh #!/bin/bash
DEV1="/dev/sdg" DEV2="/dev/sdh" DEV3="/dev/sdi"
wipefs -a $DEV1 $DEV2 $DEV3 &> /dev/null
# Create a raid1 test fs on 2 devices. mkfs.btrfs -f -m raid1 -d raid1 $DEV1 $DEV2 > /dev/null mount $DEV1 /mnt/btrfs
xfs_io -f -c "pwrite -S 0xab 0 10M" /mnt/btrfs/foo
echo "Starting to replace $DEV1 with $DEV3" btrfs replace start -B $DEV1 $DEV3 /mnt/btrfs echo
echo "Running fstrim" fstrim /mnt/btrfs echo
echo "Unmounting filesystem" umount /mnt/btrfs
echo "Mounting filesystem in degraded mode using $DEV3 only" wipefs -a $DEV1 $DEV2 &> /dev/null mount -o degraded $DEV3 /mnt/btrfs if [ $? -ne 0 ]; then dmesg | tail echo echo "Failed to mount in degraded mode" exit 1 fi
echo echo "File foo data (expected all bytes = 0xab):" od -A d -t x1 /mnt/btrfs/foo
umount /mnt/btrfs
When running the reproducer:
$ ./replace-test.sh wrote 10485760/10485760 bytes at offset 0 10 MiB, 2560 ops; 0.0901 sec (110.877 MiB/sec and 28384.5216 ops/sec) Starting to replace /dev/sdg with /dev/sdi
Running fstrim
Unmounting filesystem Mounting filesystem in degraded mode using /dev/sdi only mount: /mnt/btrfs: wrong fs type, bad option, bad superblock on /dev/sdi, missing codepage or helper program, or other error. [19581.748641] BTRFS info (device sdg): dev_replace from /dev/sdg (devid 1) to /dev/sdi started [19581.803842] BTRFS info (device sdg): dev_replace from /dev/sdg (devid 1) to /dev/sdi finished [19582.208293] BTRFS info (device sdi): allowing degraded mounts [19582.208298] BTRFS info (device sdi): disk space caching is enabled [19582.208301] BTRFS info (device sdi): has skinny extents [19582.212853] BTRFS warning (device sdi): devid 2 uuid 1f731f47-e1bb-4f00-bfbb-9e5a0cb4ba9f is missing [19582.213904] btree_readpage_end_io_hook: 25839 callbacks suppressed [19582.213907] BTRFS error (device sdi): bad tree block start, want 30490624 have 0 [19582.214780] BTRFS warning (device sdi): failed to read root (objectid=7): -5 [19582.231576] BTRFS error (device sdi): open_ctree failed
Failed to mount in degraded mode
So fix by setting all allocated ranges in the replace target device when the replace operation is finishing, when we are holding the chunk mutex and we can not race with new chunk allocations.
A test case for fstests follows soon.
Fixes: 1c11b63eff2a67 ("btrfs: replace pending/pinned chunks lists with io tree") CC: stable@vger.kernel.org # 5.2+ Reviewed-by: Nikolay Borisov nborisov@suse.com 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: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- fs/btrfs/dev-replace.c | 40 +++++++++++++++++++++++++++++++++++++++- 1 file changed, 39 insertions(+), 1 deletion(-)
--- a/fs/btrfs/dev-replace.c +++ b/fs/btrfs/dev-replace.c @@ -599,6 +599,37 @@ static void btrfs_rm_dev_replace_unblock wake_up(&fs_info->dev_replace.replace_wait); }
+/* + * When finishing the device replace, before swapping the source device with the + * target device we must update the chunk allocation state in the target device, + * as it is empty because replace works by directly copying the chunks and not + * through the normal chunk allocation path. + */ +static int btrfs_set_target_alloc_state(struct btrfs_device *srcdev, + struct btrfs_device *tgtdev) +{ + struct extent_state *cached_state = NULL; + u64 start = 0; + u64 found_start; + u64 found_end; + int ret = 0; + + lockdep_assert_held(&srcdev->fs_info->chunk_mutex); + + while (!find_first_extent_bit(&srcdev->alloc_state, start, + &found_start, &found_end, + CHUNK_ALLOCATED, &cached_state)) { + ret = set_extent_bits(&tgtdev->alloc_state, found_start, + found_end, CHUNK_ALLOCATED); + if (ret) + break; + start = found_end + 1; + } + + free_extent_state(cached_state); + return ret; +} + static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info, int scrub_ret) { @@ -673,8 +704,14 @@ static int btrfs_dev_replace_finishing(s dev_replace->time_stopped = ktime_get_real_seconds(); dev_replace->item_needs_writeback = 1;
- /* replace old device with new one in mapping tree */ + /* + * Update allocation state in the new device and replace the old device + * with the new one in the mapping tree. + */ if (!scrub_ret) { + scrub_ret = btrfs_set_target_alloc_state(src_device, tgt_device); + if (scrub_ret) + goto error; btrfs_dev_replace_update_device_in_mapping_tree(fs_info, src_device, tgt_device); @@ -685,6 +722,7 @@ static int btrfs_dev_replace_finishing(s btrfs_dev_name(src_device), src_device->devid, rcu_str_deref(tgt_device->name), scrub_ret); +error: up_write(&dev_replace->rwsem); mutex_unlock(&fs_info->chunk_mutex); mutex_unlock(&fs_info->fs_devices->device_list_mutex);