]> pilppa.com Git - linux-2.6-omap-h63xx.git/commit
[PATCH] knfsd: stop NFSD writes from being broken into lots of little writes to files...
authorNeilBrown <neilb@suse.de>
Fri, 16 Feb 2007 09:28:38 +0000 (01:28 -0800)
committerLinus Torvalds <torvalds@woody.linux-foundation.org>
Fri, 16 Feb 2007 16:14:01 +0000 (08:14 -0800)
commit29dbb3fc8020f025bc38b262ec494e19fd3eac02
tree579877f8d80e04e0908253b782b8e58c742b3fe6
parent3160a711ef754758e7f85ae371cf900252c1a392
[PATCH] knfsd: stop NFSD writes from being broken into lots of little writes to filesystem

When NFSD receives a write request, the data is typically in a number of
1448 byte segments and writev is used to collect them together.

Unfortunately, generic_file_buffered_write passes these to the filesystem
one at a time, so an e.g.  32K over-write becomes a series of partial-page
writes to each page, causing the filesystem to have to pre-read those pages
- wasted effort.

generic_file_buffered_write handles one segment of the vector at a time as
it has to pre-fault in each segment to avoid deadlocks.  When writing from
kernel-space (and nfsd does) this is not an issue, so
generic_file_buffered_write does not need to break and iovec from nfsd into
little pieces.

This patch avoids the splitting when  get_fs is KERNEL_DS as it is
from NFSd.

This issue was introduced by commit 6527c2bdf1f833cc18e8f42bd97973d583e4aa83

Acked-by: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Norman Weathers <norman.r.weathers@conocophillips.com>
Cc: Vladimir V. Saveliev <vs@namesys.com>
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm/filemap.c