block: Immutable bio vecs

[linux-block.git] / include / linux / bio.h

diff --git a/include/linux/bio.h b/include/linux/bio.h
index c16adb5f69f8b5f4f84fc2f96419b2eb0ebbb6c8..04e592e74c92b6362dfe5fd80bb0a91bacd049db 100644 (file)
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -64,11 +64,38 @@
 #define bio_iovec_idx(bio, idx)        (&((bio)->bi_io_vec[(idx)]))
 #define __bio_iovec(bio)       bio_iovec_idx((bio), (bio)->bi_iter.bi_idx)
 
-#define bio_iter_iovec(bio, iter) ((bio)->bi_io_vec[(iter).bi_idx])
+#define __bvec_iter_bvec(bvec, iter)   (&(bvec)[(iter).bi_idx])
 
-#define bio_page(bio)          (bio_iovec((bio)).bv_page)
-#define bio_offset(bio)                (bio_iovec((bio)).bv_offset)
-#define bio_iovec(bio)         (*__bio_iovec(bio))
+#define bvec_iter_page(bvec, iter)                             \
+       (__bvec_iter_bvec((bvec), (iter))->bv_page)
+
+#define bvec_iter_len(bvec, iter)                              \
+       min((iter).bi_size,                                     \
+           __bvec_iter_bvec((bvec), (iter))->bv_len - (iter).bi_bvec_done)
+
+#define bvec_iter_offset(bvec, iter)                           \
+       (__bvec_iter_bvec((bvec), (iter))->bv_offset + (iter).bi_bvec_done)
+
+#define bvec_iter_bvec(bvec, iter)                             \
+((struct bio_vec) {                                            \
+       .bv_page        = bvec_iter_page((bvec), (iter)),       \
+       .bv_len         = bvec_iter_len((bvec), (iter)),        \
+       .bv_offset      = bvec_iter_offset((bvec), (iter)),     \
+})
+
+#define bio_iter_iovec(bio, iter)                              \
+       bvec_iter_bvec((bio)->bi_io_vec, (iter))
+
+#define bio_iter_page(bio, iter)                               \
+       bvec_iter_page((bio)->bi_io_vec, (iter))
+#define bio_iter_len(bio, iter)                                        \
+       bvec_iter_len((bio)->bi_io_vec, (iter))
+#define bio_iter_offset(bio, iter)                             \
+       bvec_iter_offset((bio)->bi_io_vec, (iter))
+
+#define bio_page(bio)          bio_iter_page((bio), (bio)->bi_iter)
+#define bio_offset(bio)                bio_iter_offset((bio), (bio)->bi_iter)
+#define bio_iovec(bio)         bio_iter_iovec((bio), (bio)->bi_iter)
 
 #define bio_segments(bio)      ((bio)->bi_vcnt - (bio)->bi_iter.bi_idx)
 #define bio_sectors(bio)       ((bio)->bi_iter.bi_size >> 9)
@@ -145,16 +172,54 @@ static inline void *bio_data(struct bio *bio)
             bvl = bio_iovec_idx((bio), (i)), i < (bio)->bi_vcnt;       \
             i++)
 
+static inline void bvec_iter_advance(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");
+
+       while (bytes) {
+               unsigned len = min(bytes, bvec_iter_len(bv, *iter));
+
+               bytes -= len;
+               iter->bi_size -= len;
+               iter->bi_bvec_done += len;
+
+               if (iter->bi_bvec_done == __bvec_iter_bvec(bv, *iter)->bv_len) {
+                       iter->bi_bvec_done = 0;
+                       iter->bi_idx++;
+               }
+       }
+}
+
+#define for_each_bvec(bvl, bio_vec, iter, start)                       \
+       for ((iter) = start;                                            \
+            (bvl) = bvec_iter_bvec((bio_vec), (iter)),                 \
+               (iter).bi_size;                                         \
+            bvec_iter_advance((bio_vec), &(iter), (bvl).bv_len))
+
+
+static inline void bio_advance_iter(struct bio *bio, struct bvec_iter *iter,
+                                   unsigned bytes)
+{
+       iter->bi_sector += bytes >> 9;
+
+       if (bio->bi_rw & BIO_NO_ADVANCE_ITER_MASK)
+               iter->bi_size -= bytes;
+       else
+               bvec_iter_advance(bio->bi_io_vec, iter, bytes);
+}
+
 #define __bio_for_each_segment(bvl, bio, iter, start)                  \
        for (iter = (start);                                            \
-            bvl = bio_iter_iovec((bio), (iter)),                       \
-            (iter).bi_idx < (bio)->bi_vcnt;                            \
-            (iter).bi_idx++)
+            (iter).bi_size &&                                          \
+               ((bvl = bio_iter_iovec((bio), (iter))), 1);             \
+            bio_advance_iter((bio), &(iter), (bvl).bv_len))
 
 #define bio_for_each_segment(bvl, bio, iter)                           \
        __bio_for_each_segment(bvl, bio, iter, (bio)->bi_iter)
 
-#define bio_iter_last(bio, iter) ((iter).bi_idx == (bio)->bi_vcnt - 1)
+#define bio_iter_last(bvec, iter) ((iter).bi_size == (bvec).bv_len)
 
 /*
  * get a reference to a bio, so it won't disappear. the intended use is