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authorDmitry Monakhov <dmonakhov@openvz.org>2017-06-29 20:31:14 +0200
committerJens Axboe <axboe@kernel.dk>2017-07-04 00:56:28 +0200
commitf9df1cd99ebd82f05e8f5e0aa7e38cb8d3c791d7 (patch)
treeb5d6222cd50a8e57719e6dbbb57dd5392a07096b /include
parentblock: guard bvec iteration logic (diff)
downloadlinux-f9df1cd99ebd82f05e8f5e0aa7e38cb8d3c791d7.tar.xz
linux-f9df1cd99ebd82f05e8f5e0aa7e38cb8d3c791d7.zip
bio: add bvec_iter rewind API
Some ->bi_end_io handlers (for example: pi_verify or decrypt handlers) need to know original data vector, but after bio traverse io-stack it may be advanced, splited and relocated many times so it is hard to guess original iterator. Let's add 'bi_done' conter which accounts number of bytes iterator was advanced during it's evolution. Later end_io handler may easily restore original iterator by rewinding iterator to iter->bi_done. Note: this change makes sizeof (struct bvec_iter) multiple to 8 Reviewed-by: Hannes Reinecke <hare@suse.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org> [hch: switched to true/false return] Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'include')
-rw-r--r--include/linux/bio.h19
-rw-r--r--include/linux/bvec.h27
2 files changed, 44 insertions, 2 deletions
diff --git a/include/linux/bio.h b/include/linux/bio.h
index d5e8689f86b8..1eba19580185 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -165,14 +165,29 @@ static inline void bio_advance_iter(struct bio *bio, struct bvec_iter *iter,
{
iter->bi_sector += bytes >> 9;
- if (bio_no_advance_iter(bio))
+ if (bio_no_advance_iter(bio)) {
iter->bi_size -= bytes;
- else {
+ iter->bi_done += bytes;
+ } else {
bvec_iter_advance(bio->bi_io_vec, iter, bytes);
/* TODO: It is reasonable to complete bio with error here. */
}
}
+static inline bool bio_rewind_iter(struct bio *bio, struct bvec_iter *iter,
+ unsigned int bytes)
+{
+ iter->bi_sector -= bytes >> 9;
+
+ if (bio_no_advance_iter(bio)) {
+ iter->bi_size += bytes;
+ iter->bi_done -= bytes;
+ return true;
+ }
+
+ return bvec_iter_rewind(bio->bi_io_vec, iter, bytes);
+}
+
#define __bio_for_each_segment(bvl, bio, iter, start) \
for (iter = (start); \
(iter).bi_size && \
diff --git a/include/linux/bvec.h b/include/linux/bvec.h
index de317b4c13c1..ec8a4d7af6bd 100644
--- a/include/linux/bvec.h
+++ b/include/linux/bvec.h
@@ -40,6 +40,8 @@ struct bvec_iter {
unsigned int bi_idx; /* current index into bvl_vec */
+ unsigned int bi_done; /* number of bytes completed */
+
unsigned int bi_bvec_done; /* number of bytes completed in
current bvec */
};
@@ -83,6 +85,7 @@ static inline bool bvec_iter_advance(const struct bio_vec *bv,
bytes -= len;
iter->bi_size -= len;
iter->bi_bvec_done += len;
+ iter->bi_done += len;
if (iter->bi_bvec_done == __bvec_iter_bvec(bv, *iter)->bv_len) {
iter->bi_bvec_done = 0;
@@ -92,6 +95,30 @@ static inline bool bvec_iter_advance(const struct bio_vec *bv,
return true;
}
+static inline bool bvec_iter_rewind(const struct bio_vec *bv,
+ struct bvec_iter *iter,
+ unsigned int bytes)
+{
+ while (bytes) {
+ unsigned len = min(bytes, iter->bi_bvec_done);
+
+ if (iter->bi_bvec_done == 0) {
+ if (WARN_ONCE(iter->bi_idx == 0,
+ "Attempted to rewind iter beyond "
+ "bvec's boundaries\n")) {
+ return false;
+ }
+ iter->bi_idx--;
+ iter->bi_bvec_done = __bvec_iter_bvec(bv, *iter)->bv_len;
+ continue;
+ }
+ bytes -= len;
+ iter->bi_size += len;
+ iter->bi_bvec_done -= len;
+ }
+ return true;
+}
+
#define for_each_bvec(bvl, bio_vec, iter, start) \
for (iter = (start); \
(iter).bi_size && \