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authorChristoph Hellwig <hch@lst.de>2021-03-31 09:30:01 +0200
committerJens Axboe <axboe@kernel.dk>2021-04-06 09:28:18 -0600
commit393bb12e00580aaa23356504eed38d8f5571153a (patch)
treef1dd0bfd89dd25032f06d231bed30767d45a29a6 /block
parent9bb33f24abbd0fa2fadad01ec75438d7cc239189 (diff)
block: stop calling blk_queue_bounce for passthrough requests
Instead of overloading the passthrough fast path with the deprecated block layer bounce buffering let the users that combine an old undermaintained driver with a highmem system pay the price by always falling back to copies in that case. Signed-off-by: Christoph Hellwig <hch@lst.de> Acked-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Link: https://lore.kernel.org/r/20210331073001.46776-9-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block')
-rw-r--r--block/blk-map.c116
-rw-r--r--block/bounce.c11
2 files changed, 32 insertions, 95 deletions
diff --git a/block/blk-map.c b/block/blk-map.c
index b62b52dcb61d..dac78376acc8 100644
--- a/block/blk-map.c
+++ b/block/blk-map.c
@@ -123,7 +123,6 @@ static int bio_uncopy_user(struct bio *bio)
bio_free_pages(bio);
}
kfree(bmd);
- bio_put(bio);
return ret;
}
@@ -132,7 +131,7 @@ static int bio_copy_user_iov(struct request *rq, struct rq_map_data *map_data,
{
struct bio_map_data *bmd;
struct page *page;
- struct bio *bio, *bounce_bio;
+ struct bio *bio;
int i = 0, ret;
int nr_pages;
unsigned int len = iter->count;
@@ -218,16 +217,9 @@ static int bio_copy_user_iov(struct request *rq, struct rq_map_data *map_data,
bio->bi_private = bmd;
- bounce_bio = bio;
- ret = blk_rq_append_bio(rq, &bounce_bio);
+ ret = blk_rq_append_bio(rq, bio);
if (ret)
goto cleanup;
-
- /*
- * We link the bounce buffer in and could have to traverse it later, so
- * we have to get a ref to prevent it from being freed
- */
- bio_get(bounce_bio);
return 0;
cleanup:
if (!map_data)
@@ -242,7 +234,7 @@ static int bio_map_user_iov(struct request *rq, struct iov_iter *iter,
gfp_t gfp_mask)
{
unsigned int max_sectors = queue_max_hw_sectors(rq->q);
- struct bio *bio, *bounce_bio;
+ struct bio *bio;
int ret;
int j;
@@ -304,49 +296,17 @@ static int bio_map_user_iov(struct request *rq, struct iov_iter *iter,
break;
}
- /*
- * Subtle: if we end up needing to bounce a bio, it would normally
- * disappear when its bi_end_io is run. However, we need the original
- * bio for the unmap, so grab an extra reference to it
- */
- bio_get(bio);
-
- bounce_bio = bio;
- ret = blk_rq_append_bio(rq, &bounce_bio);
+ ret = blk_rq_append_bio(rq, bio);
if (ret)
- goto out_put_orig;
-
- /*
- * We link the bounce buffer in and could have to traverse it
- * later, so we have to get a ref to prevent it from being freed
- */
- bio_get(bounce_bio);
+ goto out_unmap;
return 0;
- out_put_orig:
- bio_put(bio);
out_unmap:
bio_release_pages(bio, false);
bio_put(bio);
return ret;
}
-/**
- * bio_unmap_user - unmap a bio
- * @bio: the bio being unmapped
- *
- * Unmap a bio previously mapped by bio_map_user_iov(). Must be called from
- * process context.
- *
- * bio_unmap_user() may sleep.
- */
-static void bio_unmap_user(struct bio *bio)
-{
- bio_release_pages(bio, bio_data_dir(bio) == READ);
- bio_put(bio);
- bio_put(bio);
-}
-
static void bio_invalidate_vmalloc_pages(struct bio *bio)
{
#ifdef ARCH_HAS_FLUSH_KERNEL_DCACHE_PAGE
@@ -519,33 +479,27 @@ cleanup:
* Append a bio to a passthrough request. Only works if the bio can be merged
* into the request based on the driver constraints.
*/
-int blk_rq_append_bio(struct request *rq, struct bio **bio)
+int blk_rq_append_bio(struct request *rq, struct bio *bio)
{
- struct bio *orig_bio = *bio;
struct bvec_iter iter;
struct bio_vec bv;
unsigned int nr_segs = 0;
- blk_queue_bounce(rq->q, bio);
+ if (WARN_ON_ONCE(rq->q->limits.bounce != BLK_BOUNCE_NONE))
+ return -EINVAL;
- bio_for_each_bvec(bv, *bio, iter)
+ bio_for_each_bvec(bv, bio, iter)
nr_segs++;
if (!rq->bio) {
- blk_rq_bio_prep(rq, *bio, nr_segs);
+ blk_rq_bio_prep(rq, bio, nr_segs);
} else {
- if (!ll_back_merge_fn(rq, *bio, nr_segs)) {
- if (orig_bio != *bio) {
- bio_put(*bio);
- *bio = orig_bio;
- }
+ if (!ll_back_merge_fn(rq, bio, nr_segs))
return -EINVAL;
- }
-
- rq->biotail->bi_next = *bio;
- rq->biotail = *bio;
- rq->__data_len += (*bio)->bi_iter.bi_size;
- bio_crypt_free_ctx(*bio);
+ rq->biotail->bi_next = bio;
+ rq->biotail = bio;
+ rq->__data_len += (bio)->bi_iter.bi_size;
+ bio_crypt_free_ctx(bio);
}
return 0;
@@ -566,12 +520,6 @@ EXPORT_SYMBOL(blk_rq_append_bio);
*
* A matching blk_rq_unmap_user() must be issued at the end of I/O, while
* still in process context.
- *
- * Note: The mapped bio may need to be bounced through blk_queue_bounce()
- * before being submitted to the device, as pages mapped may be out of
- * reach. It's the callers responsibility to make sure this happens. The
- * original bio must be passed back in to blk_rq_unmap_user() for proper
- * unmapping.
*/
int blk_rq_map_user_iov(struct request_queue *q, struct request *rq,
struct rq_map_data *map_data,
@@ -588,6 +536,8 @@ int blk_rq_map_user_iov(struct request_queue *q, struct request *rq,
if (map_data)
copy = true;
+ else if (blk_queue_may_bounce(q))
+ copy = true;
else if (iov_iter_alignment(iter) & align)
copy = true;
else if (queue_virt_boundary(q))
@@ -641,25 +591,21 @@ EXPORT_SYMBOL(blk_rq_map_user);
*/
int blk_rq_unmap_user(struct bio *bio)
{
- struct bio *mapped_bio;
+ struct bio *next_bio;
int ret = 0, ret2;
while (bio) {
- mapped_bio = bio;
- if (unlikely(bio_flagged(bio, BIO_BOUNCED)))
- mapped_bio = bio->bi_private;
-
if (bio->bi_private) {
- ret2 = bio_uncopy_user(mapped_bio);
+ ret2 = bio_uncopy_user(bio);
if (ret2 && !ret)
ret = ret2;
} else {
- bio_unmap_user(mapped_bio);
+ bio_release_pages(bio, bio_data_dir(bio) == READ);
}
- mapped_bio = bio;
+ next_bio = bio;
bio = bio->bi_next;
- bio_put(mapped_bio);
+ bio_put(next_bio);
}
return ret;
@@ -684,7 +630,7 @@ int blk_rq_map_kern(struct request_queue *q, struct request *rq, void *kbuf,
{
int reading = rq_data_dir(rq) == READ;
unsigned long addr = (unsigned long) kbuf;
- struct bio *bio, *orig_bio;
+ struct bio *bio;
int ret;
if (len > (queue_max_hw_sectors(q) << 9))
@@ -692,7 +638,8 @@ int blk_rq_map_kern(struct request_queue *q, struct request *rq, void *kbuf,
if (!len || !kbuf)
return -EINVAL;
- if (!blk_rq_aligned(q, addr, len) || object_is_on_stack(kbuf))
+ if (!blk_rq_aligned(q, addr, len) || object_is_on_stack(kbuf) ||
+ blk_queue_may_bounce(q))
bio = bio_copy_kern(q, kbuf, len, gfp_mask, reading);
else
bio = bio_map_kern(q, kbuf, len, gfp_mask);
@@ -703,14 +650,9 @@ int blk_rq_map_kern(struct request_queue *q, struct request *rq, void *kbuf,
bio->bi_opf &= ~REQ_OP_MASK;
bio->bi_opf |= req_op(rq);
- orig_bio = bio;
- ret = blk_rq_append_bio(rq, &bio);
- if (unlikely(ret)) {
- /* request is too big */
- bio_put(orig_bio);
- return ret;
- }
-
- return 0;
+ ret = blk_rq_append_bio(rq, bio);
+ if (unlikely(ret))
+ bio_put(bio);
+ return ret;
}
EXPORT_SYMBOL(blk_rq_map_kern);
diff --git a/block/bounce.c b/block/bounce.c
index 6bafc0d1f867..94081e013c58 100644
--- a/block/bounce.c
+++ b/block/bounce.c
@@ -180,12 +180,8 @@ static struct bio *bounce_clone_bio(struct bio *bio_src)
* asking for trouble and would force extra work on
* __bio_clone_fast() anyways.
*/
- if (bio_is_passthrough(bio_src))
- bio = bio_kmalloc(GFP_NOIO | __GFP_NOFAIL,
- bio_segments(bio_src));
- else
- bio = bio_alloc_bioset(GFP_NOIO, bio_segments(bio_src),
- &bounce_bio_set);
+ bio = bio_alloc_bioset(GFP_NOIO, bio_segments(bio_src),
+ &bounce_bio_set);
bio->bi_bdev = bio_src->bi_bdev;
if (bio_flagged(bio_src, BIO_REMAPPED))
bio_set_flag(bio, BIO_REMAPPED);
@@ -245,8 +241,7 @@ void __blk_queue_bounce(struct request_queue *q, struct bio **bio_orig)
if (!bounce)
return;
- if (!bio_is_passthrough(*bio_orig) &&
- sectors < bio_sectors(*bio_orig)) {
+ if (sectors < bio_sectors(*bio_orig)) {
bio = bio_split(*bio_orig, sectors, GFP_NOIO, &bounce_bio_split);
bio_chain(bio, *bio_orig);
submit_bio_noacct(*bio_orig);

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