From: Jan Kara Date: Mon, 29 Apr 2013 22:06:17 +0000 (-0700) Subject: direct-io: fix boundary block handling X-Git-Tag: omap-for-v3.10/dt-fixes-for-merge-window~128^2~116 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=092c8d46e348b5fa4109a06d8a1246060e09dc8c;p=pandora-kernel.git direct-io: fix boundary block handling When we read/write a file sequentially, we will read/write not only the data blocks but also the indirect blocks that may not be physically adjacent to the data blocks. So filesystems set the BH_Boundary flag to submit the previous I/O before reading/writing an indirect block. However the generic direct IO code mishandles buffer_boundary(), setting sdio->boundary before each submit_page_section() call which results in sending only one page bios as underlying code thinks this page is the last in the contiguous extent. So fix the problem by setting sdio->boundary only if the current page is really the last one in the mapped extent. With this patch and "direct-io: submit bio after boundary buffer is added to it" I've measured about 10% throughput improvement of direct IO reads on ext3 with SATA harddrive (from 90 MB/s to 100 MB/s). With ramdisk, the improvement was about 3-fold (from 350 MB/s to 1.2 GB/s). For other filesystems (such as ext4), the improvements won't be as visible because the frequency of BH_Boundary flag being set is much smaller. Signed-off-by: Jan Kara Reported-by: Kazuya Mio Tested-by: Kazuya Mio Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Reading git-diff-tree failed