[PATCH v3 0/5] btrfs: fix io_uring encoded IO cleanup

Hi,

Fixes for the io_uring ENCODED_READ / ENCODED_WRITE cleanup paths.

1. Always return -EIOCBQUEUED after endio so the caller and
   btrfs_uring_read_finished() do not both clean up.

   Link: https://lore.kernel.org/linux-btrfs/[email protected]/

2. btrfs_uring_read_extent() failure skipped kfree(data->iov).

3. Unlock inode/extent in the caller on read-extent failure.

4. Do not stash encoded data in the cmd PDU across -EAGAIN.

5. Drop the unused REISSUE restore.

v2 also exported __import_iovec() and passed IO_URING_F_COMPAT.
That is not a bug with the current io_uring thread setup:
create_io_thread() copies TS_COMPAT, so import_iovec() already
sees compat iovecs. Passing the flag explicitly would still be a
cleanup, but this series does not take it.

Testing:
- xfstests btrfs/333 passed.
- kmemleak after dropping the ring on NONBLOCK encoded write/read:

  unreferenced object (size 512):
    comm "btrfs_uring_eag"
    __kmalloc_cache_noprof+0x38f/0x4a0
    btrfs_uring_encoded_write+0x78d/0x1790 [btrfs]
    btrfs_uring_cmd+0x142/0x1d0 [btrfs]
    io_uring_cmd+0x296/0x5e0

  unreferenced object (size 512):
    comm "btrfs_uring_eag"
    __kmalloc_cache_noprof+0x38f/0x4a0
    btrfs_uring_encoded_read+0x89a/0x12b0 [btrfs]
    btrfs_uring_cmd+0x173/0x1d0 [btrfs]
    io_uring_cmd+0x296/0x5e0

  After 4/5 the same repro is clean.

Changes in v3:
- Drop the __import_iovec / IO_URING_F_COMPAT patches. 
- 3/5: drop a leftover goto out_fail from v2.

Changes in v2:
- unlock in the caller (Qu Wenruo)
- address further error-path issues raised on the v1 review
- export __import_iovec(); use IO_URING_F_COMPAT
- no PDU stash across -EAGAIN; drop REISSUE helpers

v2: https://lore.kernel.org/linux-btrfs/[email protected]/
v1: https://lore.kernel.org/linux-btrfs/[email protected]/

Yang Xiuwei (5):
  btrfs: always return -EIOCBQUEUED after btrfs_uring_read_extent_endio
  btrfs: free iov when btrfs_uring_read_extent fails
  btrfs: unlock inode and extent in caller when uring read extent fails
  btrfs: don't stash uring encoded data across -EAGAIN
  btrfs: drop unused uring encoded IO REISSUE stash helpers

 fs/btrfs/inode.c |  7 +++----
 fs/btrfs/ioctl.c | 39 ++++++++++++++-------------------------
 2 files changed, 17 insertions(+), 29 deletions(-)

-- 
2.25.1