block: Consolidate duplicated bio_trim() implementations
Someone cut and pasted md's md_trim_bio() into xen-blkfront.c. Come on,
we should know better than this.
Signed-off-by: Kent Overstreet <kmo@daterainc.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Neil Brown <neilb@suse.de>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/fs/bio.c b/fs/bio.c
index ea5035d..2bdb4e2 100644
--- a/fs/bio.c
+++ b/fs/bio.c
@@ -1805,6 +1805,52 @@
EXPORT_SYMBOL(bio_split);
/**
+ * bio_trim - trim a bio
+ * @bio: bio to trim
+ * @offset: number of sectors to trim from the front of @bio
+ * @size: size we want to trim @bio to, in sectors
+ */
+void bio_trim(struct bio *bio, int offset, int size)
+{
+ /* 'bio' is a cloned bio which we need to trim to match
+ * the given offset and size.
+ * This requires adjusting bi_sector, bi_size, and bi_io_vec
+ */
+ int i;
+ struct bio_vec *bvec;
+ int sofar = 0;
+
+ size <<= 9;
+ if (offset == 0 && size == bio->bi_size)
+ return;
+
+ clear_bit(BIO_SEG_VALID, &bio->bi_flags);
+
+ bio_advance(bio, offset << 9);
+
+ bio->bi_size = size;
+
+ /* avoid any complications with bi_idx being non-zero*/
+ if (bio->bi_idx) {
+ memmove(bio->bi_io_vec, bio->bi_io_vec+bio->bi_idx,
+ (bio->bi_vcnt - bio->bi_idx) * sizeof(struct bio_vec));
+ bio->bi_vcnt -= bio->bi_idx;
+ bio->bi_idx = 0;
+ }
+ /* Make sure vcnt and last bv are not too big */
+ bio_for_each_segment(bvec, bio, i) {
+ if (sofar + bvec->bv_len > size)
+ bvec->bv_len = size - sofar;
+ if (bvec->bv_len == 0) {
+ bio->bi_vcnt = i;
+ break;
+ }
+ sofar += bvec->bv_len;
+ }
+}
+EXPORT_SYMBOL_GPL(bio_trim);
+
+/**
* bio_sector_offset - Find hardware sector offset in bio
* @bio: bio to inspect
* @index: bio_vec index