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Message-Id: <1337817771-25038-15-git-send-email-koverstreet@google.com>
Date: Wed, 23 May 2012 17:02:51 -0700
From: Kent Overstreet <koverstreet@...gle.com>
To: linux-kernel@...r.kernel.org, linux-bcache@...r.kernel.org,
dm-devel@...hat.com, linux-fsdevel@...r.kernel.org
Cc: Kent Overstreet <koverstreet@...gle.com>, tj@...nel.org,
axboe@...nel.dk, agk@...hat.com, neilb@...e.de,
drbd-dev@...ts.linbit.com, bharrosh@...asas.com, vgoyal@...hat.com,
mpatocka@...hat.com, sage@...dream.net, yehuda@...newdream.net
Subject: [PATCH v2 14/14] Gut bio_add_page()
Since generic_make_request() can now handle arbitrary size bios, all we
have to do is make sure the bvec array doesn't overflow.
Signed-off-by: Kent Overstreet <koverstreet@...gle.com>
---
fs/bio.c | 133 ++++++++++++--------------------------------------------------
1 file changed, 26 insertions(+), 107 deletions(-)
diff --git a/fs/bio.c b/fs/bio.c
index 9077a07..763e919 100644
--- a/fs/bio.c
+++ b/fs/bio.c
@@ -566,12 +566,22 @@ int bio_get_nr_vecs(struct block_device *bdev)
}
EXPORT_SYMBOL(bio_get_nr_vecs);
-static int __bio_add_page(struct request_queue *q, struct bio *bio, struct page
- *page, unsigned int len, unsigned int offset,
- unsigned short max_sectors)
+/**
+ * bio_add_page - attempt to add page to bio
+ * @bio: destination bio
+ * @page: page to add
+ * @len: vec entry length
+ * @offset: vec entry offset
+ *
+ * Attempt to add a page to the bio_vec maplist. This can fail for a
+ * number of reasons, such as the bio being full or target block device
+ * limitations. The target block device must allow bio's up to PAGE_SIZE,
+ * so it is always possible to add a single page to an empty bio.
+ */
+int bio_add_page(struct bio *bio, struct page *page,
+ unsigned int len, unsigned int offset)
{
- int retried_segments = 0;
- struct bio_vec *bvec;
+ struct bio_vec *bv;
/*
* cloned bio must not modify vec list
@@ -579,40 +589,17 @@ static int __bio_add_page(struct request_queue *q, struct bio *bio, struct page
if (unlikely(bio_flagged(bio, BIO_CLONED)))
return 0;
- if (((bio->bi_size + len) >> 9) > max_sectors)
- return 0;
-
/*
* For filesystems with a blocksize smaller than the pagesize
* we will often be called with the same page as last time and
* a consecutive offset. Optimize this special case.
*/
if (bio->bi_vcnt > 0) {
- struct bio_vec *prev = &bio->bi_io_vec[bio->bi_vcnt - 1];
-
- if (page == prev->bv_page &&
- offset == prev->bv_offset + prev->bv_len) {
- unsigned int prev_bv_len = prev->bv_len;
- prev->bv_len += len;
-
- if (q->merge_bvec_fn) {
- struct bvec_merge_data bvm = {
- /* prev_bvec is already charged in
- bi_size, discharge it in order to
- simulate merging updated prev_bvec
- as new bvec. */
- .bi_bdev = bio->bi_bdev,
- .bi_sector = bio->bi_sector,
- .bi_size = bio->bi_size - prev_bv_len,
- .bi_rw = bio->bi_rw,
- };
-
- if (q->merge_bvec_fn(q, &bvm, prev) < prev->bv_len) {
- prev->bv_len -= len;
- return 0;
- }
- }
+ bv = bio_iovec_idx(bio, bio->bi_vcnt - 1);
+ if (page == bv->bv_page &&
+ offset == bv->bv_offset + bv->bv_len) {
+ bv->bv_len += len;
goto done;
}
}
@@ -620,64 +607,17 @@ static int __bio_add_page(struct request_queue *q, struct bio *bio, struct page
if (bio->bi_vcnt >= bio->bi_max_vecs)
return 0;
- /*
- * we might lose a segment or two here, but rather that than
- * make this too complex.
- */
-
- while (bio->bi_phys_segments >= queue_max_segments(q)) {
-
- if (retried_segments)
- return 0;
-
- retried_segments = 1;
- blk_recount_segments(q, bio);
- }
-
- /*
- * setup the new entry, we might clear it again later if we
- * cannot add the page
- */
- bvec = &bio->bi_io_vec[bio->bi_vcnt];
- bvec->bv_page = page;
- bvec->bv_len = len;
- bvec->bv_offset = offset;
-
- /*
- * if queue has other restrictions (eg varying max sector size
- * depending on offset), it can specify a merge_bvec_fn in the
- * queue to get further control
- */
- if (q->merge_bvec_fn) {
- struct bvec_merge_data bvm = {
- .bi_bdev = bio->bi_bdev,
- .bi_sector = bio->bi_sector,
- .bi_size = bio->bi_size,
- .bi_rw = bio->bi_rw,
- };
-
- /*
- * merge_bvec_fn() returns number of bytes it can accept
- * at this offset
- */
- if (q->merge_bvec_fn(q, &bvm, bvec) < bvec->bv_len) {
- bvec->bv_page = NULL;
- bvec->bv_len = 0;
- bvec->bv_offset = 0;
- return 0;
- }
- }
-
- /* If we may be able to merge these biovecs, force a recount */
- if (bio->bi_vcnt && (BIOVEC_PHYS_MERGEABLE(bvec-1, bvec)))
- bio->bi_flags &= ~(1 << BIO_SEG_VALID);
+ bv = bio_iovec_idx(bio, bio->bi_vcnt);
+ bv->bv_page = page;
+ bv->bv_len = len;
+ bv->bv_offset = offset;
bio->bi_vcnt++;
- bio->bi_phys_segments++;
- done:
+done:
bio->bi_size += len;
return len;
}
+EXPORT_SYMBOL(bio_add_page);
/**
* bio_add_pc_page - attempt to add page to bio
@@ -697,31 +637,10 @@ static int __bio_add_page(struct request_queue *q, struct bio *bio, struct page
int bio_add_pc_page(struct request_queue *q, struct bio *bio, struct page *page,
unsigned int len, unsigned int offset)
{
- return __bio_add_page(q, bio, page, len, offset,
- queue_max_hw_sectors(q));
+ return bio_add_page(bio, page, len, offset);
}
EXPORT_SYMBOL(bio_add_pc_page);
-/**
- * bio_add_page - attempt to add page to bio
- * @bio: destination bio
- * @page: page to add
- * @len: vec entry length
- * @offset: vec entry offset
- *
- * Attempt to add a page to the bio_vec maplist. This can fail for a
- * number of reasons, such as the bio being full or target block device
- * limitations. The target block device must allow bio's up to PAGE_SIZE,
- * so it is always possible to add a single page to an empty bio.
- */
-int bio_add_page(struct bio *bio, struct page *page, unsigned int len,
- unsigned int offset)
-{
- struct request_queue *q = bdev_get_queue(bio->bi_bdev);
- return __bio_add_page(q, bio, page, len, offset, queue_max_sectors(q));
-}
-EXPORT_SYMBOL(bio_add_page);
-
struct bio_map_data {
struct bio_vec *iovecs;
struct sg_iovec *sgvecs;
--
1.7.9.3.327.g2980b
--
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