block: fix bio splitting on max sectors

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.

Ming Lei committed 10 years ago

Commit d0e5fbb1 parent b82dde01 file · +19 −7Browse files

Unified · Split

block/blk-merge.c+19−7

@@ -70,6 +70,18 @@ static struct bio blk_bio_write_same_split(struct request_queue q, · 69 unmodified lines
70	70	return bio_split(bio, q->limits.max_write_same_sectors, GFP_NOIO, bs);
71	71	}
72	72
	73	+static inline unsigned get_max_io_size(struct request_queue *q,
	74	+ struct bio *bio)
	75	+{
	76	+ unsigned sectors = blk_max_size_offset(q, bio->bi_iter.bi_sector);
	77	+ unsigned mask = queue_logical_block_size(q) - 1;
	78	+
	79	+ /* aligned to logical block size */
	80	+ sectors &= ~(mask >> 9);
	81	+
	82	+ return sectors;
	83	+}
	84	+
73	85	static struct bio blk_bio_segment_split(struct request_queue q,
74	86	struct bio *bio,
75	87	struct bio_set *bs,
@@ -81,6 +93,7 @@ static struct bio blk_bio_segment_split(struct request_queue q, · 5 unmodified lines
81	93	unsigned front_seg_size = bio->bi_seg_front_size;
82	94	bool do_split = true;
83	95	struct bio *new = NULL;
	96	+ const unsigned max_sectors = get_max_io_size(q, bio);
84	97
85	98	bio_for_each_segment(bv, bio, iter) {
86	99	/*
@@ -90,20 +103,19 @@ static struct bio blk_bio_segment_split(struct request_queue q, · 3 unmodified lines
90	103	if (bvprvp && bvec_gap_to_prev(q, bvprvp, bv.bv_offset))
91	104	goto split;
92	105
93		− if (sectors + (bv.bv_len >> 9) >
94		− blk_max_size_offset(q, bio->bi_iter.bi_sector)) {
	106	+ if (sectors + (bv.bv_len >> 9) > max_sectors) {
95	107	/*
96	108	* Consider this a new segment if we're splitting in
97	109	* the middle of this vector.
98	110	*/
99	111	if (nsegs < queue_max_segments(q) &&
100		− sectors < blk_max_size_offset(q,
101		− bio->bi_iter.bi_sector)) {
	112	+ sectors < max_sectors) {
102	113	nsegs++;
103		− sectors = blk_max_size_offset(q,
104		− bio->bi_iter.bi_sector);
	114	+ sectors = max_sectors;
105	115	}
106		− goto split;
	116	+ if (sectors)
	117	+ goto split;
	118	+ /* Make this single bvec as the 1st segment */
107	119	}
108	120
109	121	if (bvprvp && blk_queue_cluster(q)) {