do_mpage_readpage(): don't submit lots of small bios on boundary
While tracing I/O patterns with blktrace (a great tool) a few weeks ago I identified a minor issue in fs/mpage.c As the comment above mpage_readpages() says, a fs's get_block function will set BH_Boundary when it maps a block just before a block for which extra I/O is required. Since get_block() can map a range of pages, for all these pages the BH_Boundary flag will be set. But we only need to push what I/O we have accumulated at the last block of this range. This makes do_mpage_readpage() send out the largest possible bio instead of a bunch of page-sized ones in the BH_Boundary case. Signed-off-by: Miquel van Smoorenburg <mikevs@xs4all.net> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: Jens Axboe <jens.axboe@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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