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author | Dongsu Park <dpark@posteo.net> | 2014-12-19 16:53:03 +0300 |
---|---|---|
committer | Jens Axboe <axboe@fb.com> | 2015-08-13 21:32:07 +0300 |
commit | 2ec3182f9c20a9eef0dacc0512cf2ca2df7be5ad (patch) | |
tree | 3d91f9da9ee949c20ae0ae6fa23b62d44c5a69e0 | |
parent | b54ffb73cadcdcff9cc1ae0e11f502407e3e2e4c (diff) | |
download | linux-2ec3182f9c20a9eef0dacc0512cf2ca2df7be5ad.tar.xz |
Documentation: update notes in biovecs about arbitrarily sized bios
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 <hch@infradead.org>
Cc: Kent Overstreet <kent.overstreet@gmail.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-doc@vger.kernel.org
Signed-off-by: Dongsu Park <dpark@posteo.net>
Signed-off-by: Ming Lin <ming.l@ssi.samsung.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
-rw-r--r-- | Documentation/block/biovecs.txt | 10 |
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 bi_size. @@ -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. |