block: fix bio splitting on max sectors

commit d0e5fbb01a67e400e82fefe4896ea40c6447ab98 upstream.

After commit e36f62042880(block: split bios to maxpossible length),
bio can be splitted in the middle of a vector entry, then it
is easy to split out one bio which size isn't aligned with block
size, especially when the block size is bigger than 512.

This patch fixes the issue by making the max io size aligned
to logical block size.

Fixes: e36f62042880(block: split bios to maxpossible length)
Reported-by: Stefan Haberland <sth@linux.vnet.ibm.com>
Cc: Keith Busch <keith.busch@intel.com>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ming Lei <tom.leiming@gmail.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/block/blk-merge.c b/block/blk-merge.c
index 6b982cacaea85abc3bebd7ea9631154d5c7e7f10..b966db8f35569fbf970a787e583333bb84b8ec91 100644 (file)
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -68,6 +68,18 @@ static struct bio *blk_bio_write_same_split(struct request_queue *q,
        return bio_split(bio, q->limits.max_write_same_sectors, GFP_NOIO, bs);
 }
 
+static inline unsigned get_max_io_size(struct request_queue *q,
+                                      struct bio *bio)
+{
+       unsigned sectors = blk_max_size_offset(q, bio->bi_iter.bi_sector);
+       unsigned mask = queue_logical_block_size(q) - 1;
+
+       /* aligned to logical block size */
+       sectors &= ~(mask >> 9);
+
+       return sectors;
+}
+
 static struct bio *blk_bio_segment_split(struct request_queue *q,
                                         struct bio *bio,
                                         struct bio_set *bs,
@@ -79,6 +91,7 @@ static struct bio *blk_bio_segment_split(struct request_queue *q,
        unsigned front_seg_size = bio->bi_seg_front_size;
        bool do_split = true;
        struct bio *new = NULL;
+       const unsigned max_sectors = get_max_io_size(q, bio);
 
        bio_for_each_segment(bv, bio, iter) {
                /*
@@ -88,20 +101,19 @@ static struct bio *blk_bio_segment_split(struct request_queue *q,
                if (bvprvp && bvec_gap_to_prev(q, bvprvp, bv.bv_offset))
                        goto split;
 
-               if (sectors + (bv.bv_len >> 9) >
-                               blk_max_size_offset(q, bio->bi_iter.bi_sector)) {
+               if (sectors + (bv.bv_len >> 9) > max_sectors) {
                        /*
                         * Consider this a new segment if we're splitting in
                         * the middle of this vector.
                         */
                        if (nsegs < queue_max_segments(q) &&
-                           sectors < blk_max_size_offset(q,
-                                               bio->bi_iter.bi_sector)) {
+                           sectors < max_sectors) {
                                nsegs++;
-                               sectors = blk_max_size_offset(q,
-                                               bio->bi_iter.bi_sector);
+                               sectors = max_sectors;
                        }
-                       goto split;
+                       if (sectors)
+                               goto split;
+                       /* Make this single bvec as the 1st segment */
                }
 
                if (bvprvp && blk_queue_cluster(q)) {