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| author | Jens Axboe <axboe@kernel.dk> | 2023-01-04 08:52:06 -0700 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2023-01-04 13:24:44 -0700 |
| commit | 9cea62b2cbabff8ed46f2df17778b624ad9dd25a (patch) | |
| tree | 2ab7dc9ca3cc8faeb269e35330697030b2d22330 | |
| parent | 613b14884b8595e20b9fac4126bf627313827fbe (diff) | |
| download | lwn-9cea62b2cbabff8ed46f2df17778b624ad9dd25a.tar.gz lwn-9cea62b2cbabff8ed46f2df17778b624ad9dd25a.zip | |
block: don't allow splitting of a REQ_NOWAIT bio
If we split a bio marked with REQ_NOWAIT, then we can trigger spurious
EAGAIN if constituent parts of that split bio end up failing request
allocations. Parts will complete just fine, but just a single failure
in one of the chained bios will yield an EAGAIN final result for the
parent bio.
Return EAGAIN early if we end up needing to split such a bio, which
allows for saner recovery handling.
Cc: stable@vger.kernel.org # 5.15+
Link: https://github.com/axboe/liburing/issues/766
Reported-by: Michael Kelley <mikelley@microsoft.com>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
| -rw-r--r-- | block/blk-merge.c | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/block/blk-merge.c b/block/blk-merge.c index 071c5f8cf0cf..b7c193d67185 100644 --- a/block/blk-merge.c +++ b/block/blk-merge.c @@ -309,6 +309,16 @@ static struct bio *bio_split_rw(struct bio *bio, const struct queue_limits *lim, *segs = nsegs; return NULL; split: + /* + * We can't sanely support splitting for a REQ_NOWAIT bio. End it + * with EAGAIN if splitting is required and return an error pointer. + */ + if (bio->bi_opf & REQ_NOWAIT) { + bio->bi_status = BLK_STS_AGAIN; + bio_endio(bio); + return ERR_PTR(-EAGAIN); + } + *segs = nsegs; /* |