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Patch "block: fix bio splitting on max sectors" has been added to the 4.4-stable tree

PATCH [email protected] 1 participant 1 message Feb 2, 2016

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This is a note to let you know that I've just added the patch titled

block: fix bio splitting on max sectors

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
block-fix-bio-splitting-on-max-sectors.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

Quoted 1 line

From d0e5fbb01a67e400e82fefe4896ea40c6447ab98 Mon Sep 17 00:00:00 2001

From: Ming Lei <[email protected]>
Date: Sat, 23 Jan 2016 08:05:33 +0800
Subject: block: fix bio splitting on max sectors

From: Ming Lei <[email protected]>

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 <[email protected]>
Cc Keith Busch <[email protected]>
Suggested-by Linus Torvalds <[email protected]>
Signed-off-by Ming Lei <[email protected]>
Signed-off-by Jens Axboe <[email protected]>
Signed-off-by Greg Kroah-Hartman <[email protected]>
---
 block/blk-merge.c |   26 +++++++++++++++++++-------
 1 file changed, 19 insertions(+), 7 deletions(-)
block/blk-merge.c +19 -7
@@ -68,6 +68,18 @@ static struct bio *blk_bio_write_same_sp
 	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
 	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
 		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)) {

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/block-fix-bio-splitting-on-max-sectors.patch queue-4.4/block-split-bios-to-max-possible-length.patch