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: stable@xxxxxxxxxx Reported-and-Tested-by: Till <till2.schaefer@xxxxxxxxxxxxxxx> Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx> --- 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 -- To unsubscribe from this list: send the line "unsubscribe linux-cifs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
