Hello, we are not quite careful enough about setting bio->bi_status in all places (see BACKGROUND below). This patch queue tries to fix this by systematically eliminating the direct assignments to bi_status sprinkled all throughout the code. Please comment.
The patches are currently still based on v6.18. GIT tree: https://git.kernel.org/pub/scm/linux/kernel/git/gfs2/linux-gfs2.git/log/?h=bio-cleanups The first version of this patch queue is avaliable here: https://lore.kernel.org/linux-block/[email protected]/ With these changes, only a few direct assignments to bio->bi_status remain, in BTRFS and in MD, and SOME OF THOSE MAY BE UNSAFE. Could the maintainers of those subsystems please have a look? Once the remaining direct assignments to bi_status are gone, we may want to think about "write protecting" bi_status to prevent unintended new direct assignments from creeping back in. BACKGROUND 'struct bio' objects start out with their bi_status field initialized to BLK_STS_OK (0). When the bio completes, that field needs to be left unchanged in case of success, and set to a BLK_STS_* error code otherwise. This is important when bios are chained (bio_chain()) because then, multiple execution contexts will race updating the same bi_status field. When an execution context resets bi_status to BLK_STS_OK (0) during bio completion, this could hide the error code of the adjacent bio in the chain. When more than a single bio fails in a chain, we know that the resulting bi_status will not be BLK_STS_OK, but we don't know which of the status error codes will survive. CRYPTO FALLBACK (SATYA TANGIRALA?) Related to chained bios but unrelated to setting bio->bi_status, blk_crypto_fallback_encrypt_bio() in block/blk-crypto-fallback.c swaps out bi_private and bi_end_io and reuses the same bio for downcalls, then restores those fields in blk_crypto_fallback_decrypt_endio() before calling bio_endio() again on the same bio. This will at the very least break with chained bios because it will mess up __bi_remaining. Thanks, Andreas Andreas Gruenbacher (17): xfs: don't clobber bi_status in xfs_zone_alloc_and_submit bio: rename bio_chain arguments bio: use bio_io_error more often bio: add bio_set_status bio: use bio_set_status for BLK_STS_* status codes bio: do not check bio->bi_status before assigning to it block: consecutive blk_status_t error codes block: fix blk_status_to_{errno,str} inconsistency block: turn blk_errors array into a macro block: optimize blk_status <=> errno conversion bio: bio_set_status from non-zero errno bio: do not check bio->bi_status before assigning to it (part 2) xfs: use bio_set_status in xfs_zone_alloc_and_submit bio: switch to bio_set_status in submit_bio_noacct bio: never set bi_status to BLK_STS_OK during completion bio: never set bi_status to BLK_STS_OK during completion (part 2) bio: add bio_endio_status block/bio-integrity-auto.c | 3 +- block/bio.c | 25 +++---- block/blk-core.c | 123 ++++++++++++++++--------------- block/blk-crypto-fallback.c | 22 +++--- block/blk-crypto-internal.h | 2 +- block/blk-crypto.c | 4 +- block/blk-merge.c | 6 +- block/blk-mq.c | 10 +-- block/fops.c | 6 +- block/t10-pi.c | 2 +- drivers/block/aoe/aoecmd.c | 8 +- drivers/block/aoe/aoedev.c | 2 +- drivers/block/drbd/drbd_int.h | 3 +- drivers/block/drbd/drbd_req.c | 7 +- drivers/block/ps3vram.c | 3 +- drivers/block/zram/zram_drv.c | 4 +- drivers/md/bcache/bcache.h | 3 +- drivers/md/bcache/request.c | 8 +- drivers/md/dm-cache-target.c | 9 ++- drivers/md/dm-ebs-target.c | 2 +- drivers/md/dm-flakey.c | 2 +- drivers/md/dm-integrity.c | 34 ++++----- drivers/md/dm-mpath.c | 6 +- drivers/md/dm-pcache/dm_pcache.c | 3 +- drivers/md/dm-raid1.c | 7 +- drivers/md/dm-thin.c | 7 +- drivers/md/dm-vdo/data-vio.c | 3 +- drivers/md/dm-verity-target.c | 2 +- drivers/md/dm-writecache.c | 7 +- drivers/md/dm-zoned-target.c | 3 +- drivers/md/dm.c | 4 +- drivers/md/md.c | 8 +- drivers/md/raid1-10.c | 3 +- drivers/md/raid1.c | 2 +- drivers/md/raid10.c | 20 +++-- drivers/md/raid5.c | 4 +- drivers/nvdimm/btt.c | 4 +- drivers/nvdimm/pmem.c | 4 +- fs/btrfs/bio.c | 8 +- fs/btrfs/direct-io.c | 2 +- fs/btrfs/raid56.c | 6 +- fs/crypto/bio.c | 2 +- fs/erofs/fileio.c | 4 +- fs/erofs/fscache.c | 8 +- fs/f2fs/data.c | 6 +- fs/f2fs/segment.c | 3 +- fs/iomap/ioend.c | 3 +- fs/verity/verify.c | 2 +- fs/xfs/xfs_aops.c | 3 +- fs/xfs/xfs_zone_alloc.c | 4 +- include/linux/bio.h | 28 ++++++- include/linux/blk_types.h | 2 +- include/linux/blkdev.h | 18 ++++- 53 files changed, 236 insertions(+), 238 deletions(-) -- 2.52.0
