commit d8983910a4045fa21022cfccf76ed13eb40fd7f5
author Fengguang Wu <wfg@mail.ustc.edu.cn> Thu Jul 19 01:48:06 2007 -0700
committer Linus Torvalds <torvalds@woody.linux-foundation.org> Thu Jul 19 10:04:44 2007 -0700
tree 81902a5157ace03a94aa4b62599a20bc87f7a1c0
parent 431a4820bfcdf7ff530e745230bafb06c9bf2d6d

readahead: pass real splice size

Pass real splice size to page_cache_readahead_ondemand().

The splice code works in chunks of 16 pages internally.  The readahead code
should be told of the overall splice size, instead of the internal chunk size.
 Otherwize bad things may happen.  Imagine some 17-page random splice reads.
The code before this patch will result in two readahead calls: readahead(16);
readahead(1); That leads to one 16-page I/O and one 32-page I/O: one extra I/O
and 31 readahead miss pages.

Signed-off-by: Fengguang Wu <wfg@mail.ustc.edu.cn>
Cc: Jens Axboe <jens.axboe@oracle.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>