Patch "block: move the bi_vcnt check out of __bio_try_merge_page" has been added to the 6.5-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

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

    block: move the bi_vcnt check out of __bio_try_merge_page

to the 6.5-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-move-the-bi_vcnt-check-out-of-__bio_try_merge_.patch
and it can be found in the queue-6.5 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 1a0e1090da4cf54b6aa51d52fc336cd29d7f007b
Author: Christoph Hellwig <hch@xxxxxx>
Date:   Mon Jul 24 09:54:29 2023 -0700

    block: move the bi_vcnt check out of __bio_try_merge_page
    
    [ Upstream commit 0eca8b6f97ac705c5806f7d062207379094fb114 ]
    
    Move the bi_vcnt out of __bio_try_merge_page and into the two callers
    that don't already have it in preparation for additional changes to
    __bio_try_merge_page.
    
    Signed-off-by: Christoph Hellwig <hch@xxxxxx>
    Reviewed-by: Jinyoung Choi <j-young.choi@xxxxxxxxxxx>
    Reviewed-by: Johannes Thumshirn <johannes.thumshirn@xxxxxxx>
    Link: https://lore.kernel.org/r/20230724165433.117645-5-hch@xxxxxx
    Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
    Stable-dep-of: 0ece1d649b6d ("bio-integrity: create multi-page bvecs in bio_integrity_add_page()")
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/block/bio.c b/block/bio.c
index fa2d5b15fa0fd..4369c9a355c3c 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -945,20 +945,17 @@ static inline bool page_is_mergeable(const struct bio_vec *bv,
 static bool __bio_try_merge_page(struct bio *bio, struct page *page,
 		unsigned int len, unsigned int off, bool *same_page)
 {
-	if (bio->bi_vcnt > 0) {
-		struct bio_vec *bv = &bio->bi_io_vec[bio->bi_vcnt - 1];
-
-		if (page_is_mergeable(bv, page, len, off, same_page)) {
-			if (bio->bi_iter.bi_size > UINT_MAX - len) {
-				*same_page = false;
-				return false;
-			}
-			bv->bv_len += len;
-			bio->bi_iter.bi_size += len;
-			return true;
-		}
+	struct bio_vec *bv = &bio->bi_io_vec[bio->bi_vcnt - 1];
+
+	if (!page_is_mergeable(bv, page, len, off, same_page))
+		return false;
+	if (bio->bi_iter.bi_size > UINT_MAX - len) {
+		*same_page = false;
+		return false;
 	}
-	return false;
+	bv->bv_len += len;
+	bio->bi_iter.bi_size += len;
+	return true;
 }
 
 /*
@@ -1129,11 +1126,13 @@ int bio_add_page(struct bio *bio, struct page *page,
 	if (WARN_ON_ONCE(bio_flagged(bio, BIO_CLONED)))
 		return 0;
 
-	if (!__bio_try_merge_page(bio, page, len, offset, &same_page)) {
-		if (bio_full(bio, len))
-			return 0;
-		__bio_add_page(bio, page, len, offset);
-	}
+	if (bio->bi_vcnt > 0 &&
+	    __bio_try_merge_page(bio, page, len, offset, &same_page))
+		return len;
+
+	if (bio_full(bio, len))
+		return 0;
+	__bio_add_page(bio, page, len, offset);
 	return len;
 }
 EXPORT_SYMBOL(bio_add_page);
@@ -1207,13 +1206,13 @@ static int bio_iov_add_page(struct bio *bio, struct page *page,
 {
 	bool same_page = false;
 
-	if (!__bio_try_merge_page(bio, page, len, offset, &same_page)) {
-		__bio_add_page(bio, page, len, offset);
+	if (bio->bi_vcnt > 0 &&
+	    __bio_try_merge_page(bio, page, len, offset, &same_page)) {
+		if (same_page)
+			bio_release_page(bio, page);
 		return 0;
 	}
-
-	if (same_page)
-		bio_release_page(bio, page);
+	__bio_add_page(bio, page, len, offset);
 	return 0;
 }