[0/2] btrfs: zoned: fixes for data relocation

Message

Naohiro Aota June 6, 2022, 3:59 p.m. UTC

There are two long-standing potential bugs in the data relocation path of
zoned btrfs. They are recently revealed by commit 5f0addf7b890 ("btrfs:
zoned: use dedicated lock for data relocation"). One is a mixed issue of
WRITE (for relocation extents) and ZONE APPEND (for regular extent) at the
same time, which confuses the write pointer. The other one is a too short
critical section, which can cause an out-of-order issue of the IOs.

Actually, these bugs are easily reproducible with a smaller zone size (e.g,
128 MB) with fstests btrfs/232. For example, IO failures occurs like this:

  [99909.031820][T4038707] WARNING: CPU: 3 PID: 4038707 at fs/btrfs/extent-tree.c:2381 btrfs_cross_ref_exist+0xfc/0x120 [btrfs]
  <snip>
  [99909.268769][T4038707] Call Trace:
  [99909.272105][T4038707]  <TASK>
  [99909.275093][T4038707]  run_delalloc_nocow+0x7f1/0x11a0 [btrfs]
  [99909.280996][T4038707]  ? test_range_bit+0x174/0x320 [btrfs]
  [99909.286622][T4038707]  ? fallback_to_cow+0x980/0x980 [btrfs]
  [99909.292333][T4038707]  ? find_lock_delalloc_range+0x33e/0x3e0 [btrfs]
  [99909.298825][T4038707]  btrfs_run_delalloc_range+0x445/0x1320 [btrfs]
  [99909.305222][T4038707]  ? test_range_bit+0x320/0x320 [btrfs]
  [99909.310844][T4038707]  ? lock_downgrade+0x6a0/0x6a0
  [99909.315732][T4038707]  ? orc_find.part.0+0x1ed/0x300
  [99909.320705][T4038707]  ? __module_address.part.0+0x25/0x300
  [99909.326280][T4038707]  writepage_delalloc+0x159/0x310 [btrfs]
  <snip>
  [99909.883814][    C3] sd 10:0:1:0: [sde] tag#2620 FAILED Result: hostbyte=DID_OK driverbyte=DRIVER_OK cmd_age=0s
  [99909.893855][    C3] sd 10:0:1:0: [sde] tag#2620 Sense Key : Illegal Request [current]
  [99909.901819][    C3] sd 10:0:1:0: [sde] tag#2620 Add. Sense: Unaligned write command
  [99909.909525][    C3] sd 10:0:1:0: [sde] tag#2620 CDB: Write(16) 8a 00 00 00 00 00 02 f3 63 87 00 00 00 2c 00 00
  [99909.919544][    C3] critical target error, dev sde, sector 396041272 op 0x1:(WRITE) flags 0x800 phys_seg 3 prio class 0
  [99909.930329][    C3] BTRFS error (device dm-1): bdev /dev/mapper/dml_102_2 errs: wr 1, rd 0, flush 0, corrupt 0, gen 0

Or, an assertion failure occur like this:

  [   12.527832] assertion failed: start >= found_start && end <= found_end, in fs/btrfs/free-space-tree.c:737
  <snip>
  [   12.533391] Call Trace:
  [   12.533391]  <TASK>
  [   12.533391]  __remove_from_free_space_tree.cold+0x11/0x22 [btrfs]
  [   12.542073]  ? setup_items_for_insert.isra.0+0x2bf/0x3f0 [btrfs]
  [   12.542073]  remove_from_free_space_tree+0x80/0x110 [btrfs]
  [   12.542073]  alloc_reserved_file_extent+0x1b4/0x240 [btrfs]
  [   12.542073]  __btrfs_run_delayed_refs+0x692/0xf30 [btrfs]
  [   12.542073]  ? btrfs_btree_balance_dirty+0x2f/0x50 [btrfs]
  [   12.542073]  btrfs_run_delayed_refs+0x81/0x1e0 [btrfs]
  [   12.542073]  btrfs_commit_transaction+0x54/0xaf0 [btrfs]
  [   12.542073]  ? start_transaction+0xc2/0x5b0 [btrfs]
  [   12.542073]  ? _raw_read_lock_irqsave+0x20/0x40
  [   12.542073]  relocate_block_group+0x320/0x550 [btrfs]
  [   12.542073]  btrfs_relocate_block_group+0x1f9/0x3a0 [btrfs]
  [   12.542073]  btrfs_relocate_chunk+0x36/0xf0 [btrfs]
  [   12.542073]  btrfs_reclaim_bgs_work.cold+0x4f/0x74 [btrfs]
  [   12.542073]  process_one_work+0x1b0/0x310
  [   12.542073]  worker_thread+0x48/0x3d0
  [   12.542073]  ? rescuer_thread+0x3a0/0x3a0
  [   12.542073]  kthread+0xed/0x120
  [   12.550506]  ? kthread_complete_and_exit+0x20/0x20
  [   12.550506]  ret_from_fork+0x22/0x30
  [   12.550506]  </TASK>

This series fixes the two issues. The first one is fixed by introducing a
new btrfs_block_group bit to disallow extent allocation but still allow
nocow writes to start.

The second one is simply fixed by extending the critical section.

Naohiro Aota (2):
  btrfs: zoned: prevent allocation from previous data relocation BG
  btrfs: zoned: fix critical section of relocation inode writeback

 fs/btrfs/block-group.h |  1 +
 fs/btrfs/extent-tree.c | 20 ++++++++++++++++++--
 fs/btrfs/extent_io.c   |  3 ++-
 fs/btrfs/inode.c       |  2 ++
 fs/btrfs/zoned.c       | 27 +++++++++++++++++++++++++++
 fs/btrfs/zoned.h       |  5 +++++
 6 files changed, 55 insertions(+), 3 deletions(-)