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authorChristoph Hellwig <hch@lst.de>2010-06-18 16:59:42 +0200
committerJens Axboe <jaxboe@fusionio.com>2010-08-07 18:23:08 +0200
commit66ac0280197981f88774e74b60c8e5f9f07c1dba (patch)
treed093ce493146779926df88b5831805c6f9ee14e1 /block
parent082439004b31adc146e96e5f1c574dd2b57dcd93 (diff)
downloadlinux-linaro-stable-66ac0280197981f88774e74b60c8e5f9f07c1dba.tar.gz
block: don't allocate a payload for discard request
Allocating a fixed payload for discard requests always was a horrible hack, and it's not coming to byte us when adding support for discard in DM/MD. So change the code to leave the allocation of a payload to the lowlevel driver. Unfortunately that means we'll need another hack, which allows us to update the various block layer length fields indicating that we have a payload. Instead of hiding this in sd.c, which we already partially do for UNMAP support add a documented helper in the core block layer for it. Signed-off-by: Christoph Hellwig <hch@lst.de> Acked-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
Diffstat (limited to 'block')
-rw-r--r--block/blk-core.c32
-rw-r--r--block/blk-lib.c33
2 files changed, 38 insertions, 27 deletions
diff --git a/block/blk-core.c b/block/blk-core.c
index 66c3cfe94d0a..3531d8e1da04 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1135,6 +1135,38 @@ void blk_put_request(struct request *req)
}
EXPORT_SYMBOL(blk_put_request);
+/**
+ * blk_add_request_payload - add a payload to a request
+ * @rq: request to update
+ * @page: page backing the payload
+ * @len: length of the payload.
+ *
+ * This allows to later add a payload to an already submitted request by
+ * a block driver. The driver needs to take care of freeing the payload
+ * itself.
+ *
+ * Note that this is a quite horrible hack and nothing but handling of
+ * discard requests should ever use it.
+ */
+void blk_add_request_payload(struct request *rq, struct page *page,
+ unsigned int len)
+{
+ struct bio *bio = rq->bio;
+
+ bio->bi_io_vec->bv_page = page;
+ bio->bi_io_vec->bv_offset = 0;
+ bio->bi_io_vec->bv_len = len;
+
+ bio->bi_size = len;
+ bio->bi_vcnt = 1;
+ bio->bi_phys_segments = 1;
+
+ rq->__data_len = rq->resid_len = len;
+ rq->nr_phys_segments = 1;
+ rq->buffer = bio_data(bio);
+}
+EXPORT_SYMBOL_GPL(blk_add_request_payload);
+
void init_request_from_bio(struct request *req, struct bio *bio)
{
req->cpu = bio->bi_comp_cpu;
diff --git a/block/blk-lib.c b/block/blk-lib.c
index d0216b9f22d4..e16185b0d8e1 100644
--- a/block/blk-lib.c
+++ b/block/blk-lib.c
@@ -19,7 +19,6 @@ static void blkdev_discard_end_io(struct bio *bio, int err)
if (bio->bi_private)
complete(bio->bi_private);
- __free_page(bio_page(bio));
bio_put(bio);
}
@@ -43,7 +42,6 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
int type = flags & BLKDEV_IFL_BARRIER ?
DISCARD_BARRIER : DISCARD_NOBARRIER;
struct bio *bio;
- struct page *page;
int ret = 0;
if (!q)
@@ -53,35 +51,21 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
return -EOPNOTSUPP;
while (nr_sects && !ret) {
- unsigned int sector_size = q->limits.logical_block_size;
unsigned int max_discard_sectors =
min(q->limits.max_discard_sectors, UINT_MAX >> 9);
bio = bio_alloc(gfp_mask, 1);
- if (!bio)
- goto out;
+ if (!bio) {
+ ret = -ENOMEM;
+ break;
+ }
+
bio->bi_sector = sector;
bio->bi_end_io = blkdev_discard_end_io;
bio->bi_bdev = bdev;
if (flags & BLKDEV_IFL_WAIT)
bio->bi_private = &wait;
- /*
- * Add a zeroed one-sector payload as that's what
- * our current implementations need. If we'll ever need
- * more the interface will need revisiting.
- */
- page = alloc_page(gfp_mask | __GFP_ZERO);
- if (!page)
- goto out_free_bio;
- if (bio_add_pc_page(q, bio, page, sector_size, 0) < sector_size)
- goto out_free_page;
-
- /*
- * And override the bio size - the way discard works we
- * touch many more blocks on disk than the actual payload
- * length.
- */
if (nr_sects > max_discard_sectors) {
bio->bi_size = max_discard_sectors << 9;
nr_sects -= max_discard_sectors;
@@ -103,13 +87,8 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
ret = -EIO;
bio_put(bio);
}
+
return ret;
-out_free_page:
- __free_page(page);
-out_free_bio:
- bio_put(bio);
-out:
- return -ENOMEM;
}
EXPORT_SYMBOL(blkdev_issue_discard);