This is a note to let you know that I've just added the patch titled
cifs: set ra_pages in backing_dev_info
to the 2.6.38-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
cifs-set-ra_pages-in-backing_dev_info.patch
and it can be found in the queue-2.6.38 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From 2b6c26a0a62cc0bab0ad487533d5581d7c293fef Mon Sep 17 00:00:00 2001
From: Jeff Layton <[email protected]>
Date: Fri, 25 Mar 2011 16:25:57 -0400
Subject: cifs: set ra_pages in backing_dev_info
From: Jeff Layton <[email protected]>
commit 2b6c26a0a62cc0bab0ad487533d5581d7c293fef upstream.
Commit 522440ed made cifs set backing_dev_info on the mapping attached
to new inodes. This change caused a fairly significant read performance
regression, as cifs started doing page-sized reads exclusively.
By virtue of the fact that they're allocated as part of cifs_sb_info by
kzalloc, the ra_pages on cifs BDIs get set to 0, which prevents any
readahead. This forces the normal read codepaths to use readpage instead
of readpages causing a four-fold increase in the number of read calls
with the default rsize.
Fix it by setting ra_pages in the BDI to the same value as that in the
default_backing_dev_info.
Fixes https://bugzilla.kernel.org/show_bug.cgi?id=31662
Reported-and-Tested-by: Till <[email protected]>
Signed-off-by: Jeff Layton <[email protected]>
Signed-off-by: Steve French <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
fs/cifs/cifsfs.c | 1 +
1 file changed, 1 insertion(+)
--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -127,6 +127,7 @@ cifs_read_super(struct super_block *sb,
kfree(cifs_sb);
return rc;
}
+ cifs_sb->bdi.ra_pages = default_backing_dev_info.ra_pages;
#ifdef CONFIG_CIFS_DFS_UPCALL
/* copy mount params to sb for use in submounts */
Patches currently in stable-queue which might be from [email protected] are
queue-2.6.38/cifs-set-ra_pages-in-backing_dev_info.patch
queue-2.6.38/cifs-wrap-received-signature-check-in-srv_mutex.patch
queue-2.6.38/cifs-always-do-is_path_accessible-check-in-cifs_mount.patch
queue-2.6.38/cifs-check-for-private_data-before-trying-to-put-it.patch
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