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authorKent Overstreet <koverstreet@google.com>2012-09-29 00:17:55 +0400
committerKent Overstreet <koverstreet@google.com>2013-03-24 01:15:27 +0400
commit054bdf646e36c2f7dc1bf6bc6209dbbb5909164b (patch)
treeacd9989fd9e6f5c6d3c985e34e984081a33cbdc3 /fs/bio.c
parent9f060e2231ca96ca94f2ffcff730acd72606b280 (diff)
downloadlinux-054bdf646e36c2f7dc1bf6bc6209dbbb5909164b.tar.xz
block: Add bio_advance()
This is prep work for immutable bio vecs; we first want to centralize where bvecs are modified. Next two patches convert some existing code to use this function. Signed-off-by: Kent Overstreet <koverstreet@google.com> CC: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'fs/bio.c')
-rw-r--r--fs/bio.c41
1 files changed, 41 insertions, 0 deletions
diff --git a/fs/bio.c b/fs/bio.c
index 40aa96eae99f..7edc08d2246c 100644
--- a/fs/bio.c
+++ b/fs/bio.c
@@ -752,6 +752,47 @@ int bio_add_page(struct bio *bio, struct page *page, unsigned int len,
}
EXPORT_SYMBOL(bio_add_page);
+/**
+ * bio_advance - increment/complete a bio by some number of bytes
+ * @bio: bio to advance
+ * @bytes: number of bytes to complete
+ *
+ * This updates bi_sector, bi_size and bi_idx; if the number of bytes to
+ * complete doesn't align with a bvec boundary, then bv_len and bv_offset will
+ * be updated on the last bvec as well.
+ *
+ * @bio will then represent the remaining, uncompleted portion of the io.
+ */
+void bio_advance(struct bio *bio, unsigned bytes)
+{
+ if (bio_integrity(bio))
+ bio_integrity_advance(bio, bytes);
+
+ bio->bi_sector += bytes >> 9;
+ bio->bi_size -= bytes;
+
+ if (bio->bi_rw & BIO_NO_ADVANCE_ITER_MASK)
+ return;
+
+ while (bytes) {
+ if (unlikely(bio->bi_idx >= bio->bi_vcnt)) {
+ WARN_ONCE(1, "bio idx %d >= vcnt %d\n",
+ bio->bi_idx, bio->bi_vcnt);
+ break;
+ }
+
+ if (bytes >= bio_iovec(bio)->bv_len) {
+ bytes -= bio_iovec(bio)->bv_len;
+ bio->bi_idx++;
+ } else {
+ bio_iovec(bio)->bv_len -= bytes;
+ bio_iovec(bio)->bv_offset += bytes;
+ bytes = 0;
+ }
+ }
+}
+EXPORT_SYMBOL(bio_advance);
+
struct bio_map_data {
struct bio_vec *iovecs;
struct sg_iovec *sgvecs;