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blk-merge: fix blk_recount_segments

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QUEUE_FLAG_NO_SG_MERGE is set at default for blk-mq devices,
so bio->bi_phys_segment computed may be bigger than
queue_max_segments(q) for blk-mq devices, then drivers will
fail to handle the case, for example, BUG_ON() in
virtio_queue_rq() can be triggerd for virtio-blk:

	https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1359146

This patch fixes the issue by ignoring the QUEUE_FLAG_NO_SG_MERGE
flag if the computed bio->bi_phys_segment is bigger than
queue_max_segments(q), and the regression is caused by commit
05f1dd53152173(block: add queue flag for disabling SG merging).

Reported-by: Kick In <pierre-andre.morey@canonical.com>
Tested-by: Chris J Arges <chris.j.arges@canonical.com>
Signed-off-by: Ming Lei <ming.lei@canonical.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Ming Lei 2014-09-02 23:02:59 +08:00 committed by Jens Axboe
parent 7505ceaf86
commit 0738854939
1 changed files with 11 additions and 6 deletions
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17
block/blk-merge.c
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@ -10,10 +10,11 @@
#include "blk.h" #include "blk.h"
static unsigned int __blk_recalc_rq_segments(struct request_queue *q, static unsigned int __blk_recalc_rq_segments(struct request_queue *q,
struct bio *bio) struct bio *bio,
bool no_sg_merge)
{ {
struct bio_vec bv, bvprv = { NULL }; struct bio_vec bv, bvprv = { NULL };
int cluster, high, highprv = 1, no_sg_merge; int cluster, high, highprv = 1;
unsigned int seg_size, nr_phys_segs; unsigned int seg_size, nr_phys_segs;
struct bio *fbio, *bbio; struct bio *fbio, *bbio;
struct bvec_iter iter; struct bvec_iter iter;
@ -35,7 +36,6 @@ static unsigned int __blk_recalc_rq_segments(struct request_queue *q,
cluster = blk_queue_cluster(q); cluster = blk_queue_cluster(q);
seg_size = 0; seg_size = 0;
nr_phys_segs = 0; nr_phys_segs = 0;
no_sg_merge = test_bit(QUEUE_FLAG_NO_SG_MERGE, &q->queue_flags);
high = 0; high = 0;
for_each_bio(bio) { for_each_bio(bio) {
bio_for_each_segment(bv, bio, iter) { bio_for_each_segment(bv, bio, iter) {
@ -88,18 +88,23 @@ new_segment:
void blk_recalc_rq_segments(struct request *rq) void blk_recalc_rq_segments(struct request *rq)
{ {
rq->nr_phys_segments = __blk_recalc_rq_segments(rq->q, rq->bio); bool no_sg_merge = !!test_bit(QUEUE_FLAG_NO_SG_MERGE,
&rq->q->queue_flags);
rq->nr_phys_segments = __blk_recalc_rq_segments(rq->q, rq->bio,
no_sg_merge);
} }
void blk_recount_segments(struct request_queue *q, struct bio *bio) void blk_recount_segments(struct request_queue *q, struct bio *bio)
{ {
if (test_bit(QUEUE_FLAG_NO_SG_MERGE, &q->queue_flags)) if (test_bit(QUEUE_FLAG_NO_SG_MERGE, &q->queue_flags) &&
bio->bi_vcnt < queue_max_segments(q))
bio->bi_phys_segments = bio->bi_vcnt; bio->bi_phys_segments = bio->bi_vcnt;
else { else {
struct bio *nxt = bio->bi_next; struct bio *nxt = bio->bi_next;
bio->bi_next = NULL; bio->bi_next = NULL;
bio->bi_phys_segments = __blk_recalc_rq_segments(q, bio); bio->bi_phys_segments = __blk_recalc_rq_segments(q, bio, false);
bio->bi_next = nxt; bio->bi_next = nxt;
} }