From 20d0189b1012a37d2533a87fb451f7852f2418d1 Mon Sep 17 00:00:00 2001 From: Kent Overstreet Date: Sat, 23 Nov 2013 18:21:01 -0800 Subject: block: Introduce new bio_split() The new bio_split() can split arbitrary bios - it's not restricted to single page bios, like the old bio_split() (previously renamed to bio_pair_split()). It also has different semantics - it doesn't allocate a struct bio_pair, leaving it up to the caller to handle completions. Then convert the existing bio_pair_split() users to the new bio_split() - and also nvme, which was open coding bio splitting. (We have to take that BUG_ON() out of bio_integrity_trim() because this bio_split() needs to use it, and there's no reason it has to be used on bios marked as cloned; BIO_CLONED doesn't seem to have clearly documented semantics anyways.) Signed-off-by: Kent Overstreet Cc: Jens Axboe Cc: Martin K. Petersen Cc: Matthew Wilcox Cc: Keith Busch Cc: Vishal Verma Cc: Jiri Kosina Cc: Neil Brown --- fs/bio.c | 36 ++++++++++++++++++++++++++++++++++++ 1 file changed, 36 insertions(+) (limited to 'fs/bio.c') diff --git a/fs/bio.c b/fs/bio.c index a3e753f4d5a6..7b062befac82 100644 --- a/fs/bio.c +++ b/fs/bio.c @@ -1793,6 +1793,42 @@ void bio_endio_nodec(struct bio *bio, int error) } EXPORT_SYMBOL(bio_endio_nodec); +/** + * bio_split - split a bio + * @bio: bio to split + * @sectors: number of sectors to split from the front of @bio + * @gfp: gfp mask + * @bs: bio set to allocate from + * + * Allocates and returns a new bio which represents @sectors from the start of + * @bio, and updates @bio to represent the remaining sectors. + * + * The newly allocated bio will point to @bio's bi_io_vec; it is the caller's + * responsibility to ensure that @bio is not freed before the split. + */ +struct bio *bio_split(struct bio *bio, int sectors, + gfp_t gfp, struct bio_set *bs) +{ + struct bio *split = NULL; + + BUG_ON(sectors <= 0); + BUG_ON(sectors >= bio_sectors(bio)); + + split = bio_clone_fast(bio, gfp, bs); + if (!split) + return NULL; + + split->bi_iter.bi_size = sectors << 9; + + if (bio_integrity(split)) + bio_integrity_trim(split, 0, sectors); + + bio_advance(bio, split->bi_iter.bi_size); + + return split; +} +EXPORT_SYMBOL(bio_split); + void bio_pair_release(struct bio_pair *bp) { if (atomic_dec_and_test(&bp->cnt)) { -- cgit v1.2.3