diff options
authorDongsu Park <>2014-12-19 14:53:03 +0100
committerJens Axboe <>2015-08-13 12:32:07 -0600
commit2ec3182f9c20a9eef0dacc0512cf2ca2df7be5ad (patch)
parentb54ffb73cadcdcff9cc1ae0e11f502407e3e2e4c (diff)
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 <> Cc: Kent Overstreet <> Cc: Jonathan Corbet <> Cc: Signed-off-by: Dongsu Park <> Signed-off-by: Ming Lin <> Signed-off-by: Jens Axboe <>
1 files changed, 9 insertions, 1 deletions
diff --git a/Documentation/block/biovecs.txt b/Documentation/block/biovecs.txt
index 74a32ad52f53..25689584e6e0 100644
--- a/Documentation/block/biovecs.txt
+++ b/Documentation/block/biovecs.txt
@@ -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
+ drivers.