BugLink: http://bugs.launchpad.net/bugs/769042
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 <till2.schaefer@uni-dortmund.de>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Leann Ogasawara <leann.ogasawara@canonical.com>
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 */