diff options
| author |   Ming Lei <ming.lei@redhat.com> | 2017-12-18 20:22:09 +0800 |
|---|---|---|
| committer |   Jens Axboe <axboe@kernel.dk> | 2018-01-06 09:18:00 -0700 |
| commit | c2421edf5f9151d0eb28affbf76e9e4f8ddd03c6 (patch) | |
| tree | 2b766d69e02c2941c2996e2902b54fc859625751 /drivers/md/bcache | |
| parent | dm: limit the max bio size as BIO_MAX_PAGES * PAGE_SIZE (diff) | |
| download | linux-dev-c2421edf5f9151d0eb28affbf76e9e4f8ddd03c6.tar.xz linux-dev-c2421edf5f9151d0eb28affbf76e9e4f8ddd03c6.zip | |
bcache: comment on direct access to bvec table
All direct access to bvec table are safe even after multipage bvec is
supported.
Cc: linux-bcache@vger.kernel.org
Acked-by: Coly Li <colyli@suse.de>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'drivers/md/bcache')
| -rw-r--r-- | drivers/md/bcache/btree.c | 1 | ||||
| -rw-r--r-- | drivers/md/bcache/util.c | 7 |
2 files changed, 8 insertions, 0 deletions
diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c index 81e8dc3dbe5e..02a4cf646fdc 100644 --- a/drivers/md/bcache/btree.c +++ b/drivers/md/bcache/btree.c @@ -432,6 +432,7 @@ static void do_btree_node_write(struct btree *b) continue_at(cl, btree_node_write_done, NULL); } else { + /* No problem for multipage bvec since the bio is just allocated */ b->bio->bi_vcnt = 0; bch_bio_map(b->bio, i); diff --git a/drivers/md/bcache/util.c b/drivers/md/bcache/util.c index e548b8b51322..61813d230015 100644 --- a/drivers/md/bcache/util.c +++ b/drivers/md/bcache/util.c @@ -249,6 +249,13 @@ uint64_t bch_next_delay(struct bch_ratelimit *d, uint64_t done) : 0; } +/* + * Generally it isn't good to access .bi_io_vec and .bi_vcnt directly, + * the preferred way is bio_add_page, but in this case, bch_bio_map() + * supposes that the bvec table is empty, so it is safe to access + * .bi_vcnt & .bi_io_vec in this way even after multipage bvec is + * supported. + */ void bch_bio_map(struct bio *bio, void *base) { size_t size = bio->bi_iter.bi_size; |