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authorJens Axboe <axboe@kernel.dk>2023-01-04 08:52:06 -0700
committerJens Axboe <axboe@kernel.dk>2023-01-04 13:24:44 -0700
commit9cea62b2cbabff8ed46f2df17778b624ad9dd25a (patch)
tree2ab7dc9ca3cc8faeb269e35330697030b2d22330 /block/blk-merge.c
parent613b14884b8595e20b9fac4126bf627313827fbe (diff)
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>
Diffstat (limited to 'block/blk-merge.c')
-rw-r--r--block/blk-merge.c10
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;
/*