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.
Cc: sta...@kernel.org
Reported-and-Tested-by: Till <till2.schae...@uni-dortmund.de>
Signed-off-by: Jeff Layton <jlay...@redhat.com>
---
fs/cifs/cifsfs.c | 1 +
1 files changed, 1 insertions(+), 0 deletions(-)
diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
index 1af2470..fb6a2ad 100644
--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -131,6 +131,7 @@ cifs_read_super(struct super_block *sb, void *data,
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 */
--
1.7.4.1
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