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-rw-r--r--include/linux/bvec.h41
1 files changed, 36 insertions, 5 deletions
diff --git a/include/linux/bvec.h b/include/linux/bvec.h
index 89b65b82d98f..ec8a4d7af6bd 100644
--- a/include/linux/bvec.h
+++ b/include/linux/bvec.h
@@ -22,6 +22,7 @@
#include <linux/kernel.h>
#include <linux/bug.h>
+#include <linux/errno.h>
/*
* was unsigned short, but we might as well be ready for > 64kB I/O pages
@@ -39,6 +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 */
};
@@ -66,12 +69,14 @@ struct bvec_iter {
.bv_offset = bvec_iter_offset((bvec), (iter)), \
})
-static inline void bvec_iter_advance(const struct bio_vec *bv,
- struct bvec_iter *iter,
- unsigned bytes)
+static inline bool bvec_iter_advance(const struct bio_vec *bv,
+ struct bvec_iter *iter, unsigned bytes)
{
- WARN_ONCE(bytes > iter->bi_size,
- "Attempted to advance past end of bvec iter\n");
+ if (WARN_ONCE(bytes > iter->bi_size,
+ "Attempted to advance past end of bvec iter\n")) {
+ iter->bi_size = 0;
+ return false;
+ }
while (bytes) {
unsigned iter_len = bvec_iter_len(bv, *iter);
@@ -80,12 +85,38 @@ static inline void 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;
iter->bi_idx++;
}
}
+ 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) \