redonkable
/
alistair23-linux
1
0
Fork 0
Code Releases Activity

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 <jack@suse.cz>
Reported-by: Kazuya Mio <k-mio@sx.jp.nec.com>
Tested-by: Kazuya Mio <k-mio@sx.jp.nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
hifive-unleashed-5.1
Jan Kara 2013-04-29 15:06:17 -07:00 committed by Linus Torvalds
parent e05c4bbfae
commit 092c8d46e3
1 changed files with 2 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
fs/direct-io.c
View File

@ -969,7 +969,8 @@ do_holes:
this_chunk_bytes = this_chunk_blocks << blkbits;
BUG_ON(this_chunk_bytes == 0);
sdio->boundary = buffer_boundary(map_bh);
if (this_chunk_blocks == sdio->blocks_available)
sdio->boundary = buffer_boundary(map_bh);
ret = submit_page_section(dio, sdio, page,
offset_in_page,
this_chunk_bytes,