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Diffstat (limited to 'Documentation/block/biovecs.rst')
| -rw-r--r-- | Documentation/block/biovecs.rst | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/Documentation/block/biovecs.rst b/Documentation/block/biovecs.rst index 86fa66c87172..b9dc0c9dbee4 100644 --- a/Documentation/block/biovecs.rst +++ b/Documentation/block/biovecs.rst @@ -40,6 +40,8 @@ normal code doesn't have to deal with bi_bvec_done. There is a lower level advance function - bvec_iter_advance() - which takes a pointer to a biovec, not a bio; this is used by the bio integrity code. +As of 5.12 bvec segments with zero bv_len are not supported. + What's all this get us? ======================= @@ -47,7 +49,7 @@ Having a real iterator, and making biovecs immutable, has a number of advantages: * Before, iterating over bios was very awkward when you weren't processing - exactly one bvec at a time - for example, bio_copy_data() in fs/bio.c, + exactly one bvec at a time - for example, bio_copy_data() in block/bio.c, which copies the contents of one bio into another. Because the biovecs wouldn't necessarily be the same size, the old code was tricky convoluted - it had to walk two different bios at the same time, keeping both bi_idx and @@ -129,8 +131,10 @@ Usage of helpers: :: bio_for_each_segment_all() + bio_for_each_bvec_all() bio_first_bvec_all() bio_first_page_all() + bio_first_folio_all() bio_last_bvec_all() * The following helpers iterate over single-page segment. The passed 'struct @@ -143,4 +147,5 @@ Usage of helpers: bio_vec' will contain a multi-page IO vector during the iteration:: bio_for_each_bvec() + bio_for_each_bvec_all() rq_for_each_bvec() |