|author||Dongsu Park <firstname.lastname@example.org>||2014-12-19 14:53:03 +0100|
|committer||Jens Axboe <email@example.com>||2015-08-13 12:32:07 -0600|
Documentation: update notes in biovecs about arbitrarily sized biosfor-4.3/immutable-vecs
Update block/biovecs.txt so that it includes a note on what kind of effects arbitrarily sized bios would bring to the block layer. Also fix a trivial typo, bio_iter_iovec. Cc: Christoph Hellwig <firstname.lastname@example.org> Cc: Kent Overstreet <email@example.com> Cc: Jonathan Corbet <firstname.lastname@example.org> Cc: email@example.com Signed-off-by: Dongsu Park <firstname.lastname@example.org> Signed-off-by: Ming Lin <email@example.com> Signed-off-by: Jens Axboe <firstname.lastname@example.org>
1 files changed, 9 insertions, 1 deletions
diff --git a/Documentation/block/biovecs.txt b/Documentation/block/biovecs.txt
index 74a32ad52f53..25689584e6e0 100644
@@ -24,7 +24,7 @@ particular, presenting the illusion of partially completed biovecs so that
normal code doesn't have to deal with bi_bvec_done.
* Driver code should no longer refer to biovecs directly; we now have
- bio_iovec() and bio_iovec_iter() macros that return literal struct biovecs,
+ bio_iovec() and bio_iter_iovec() macros that return literal struct biovecs,
constructed from the raw biovecs but taking into account bi_bvec_done and
@@ -109,3 +109,11 @@ Other implications:
over all the biovecs in the new bio - which is silly as it's not needed.
So, don't use bi_vcnt anymore.
+ * The current interface allows the block layer to split bios as needed, so we
+ could eliminate a lot of complexity particularly in stacked drivers. Code
+ that creates bios can then create whatever size bios are convenient, and
+ more importantly stacked drivers don't have to deal with both their own bio
+ size limitations and the limitations of the underlying devices. Thus
+ there's no need to define ->merge_bvec_fn() callbacks for individual block