dm-nfs: force random mode for the backend file

Orabug: 14092678
Without this flag page_cache_sync_readahead() might take some seconds to
complete.
Since dm-nfs used for ovm and as vdisk, random access is expect, so force
set this flag when open the backend file.

Signed-off-by: Joe Jin <joe.jin@oracle.com>
Cc: Adnan Misherfi <adnan.misherfi@oracle.com>
Cc: Kurt C Hackel <kurt.hackel@oracle.com>
Cc: Andrew Thomas <andrew.thomas@oracle.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

diff --git a/drivers/md/dm-nfs.c b/drivers/md/dm-nfs.c
index 2ee7e5ff91792c98eb44e152216df45d068bb36c..e03b9948307e93d9fc50f663aabec04d38d58d85 100644 (file)
--- a/drivers/md/dm-nfs.c
+++ b/drivers/md/dm-nfs.c
@@ -197,6 +197,9 @@ static int dm_nfs_io_get_file(struct dm_target *ti, uid_t uid)
        filp = filp_open(nc->path, flags, 0);
        if (IS_ERR(filp))
                return PTR_ERR(filp);
+
+       /* Force random reference */
+       filp->f_mode |= FMODE_RANDOM;
        nc->filp = filp;
 
        r = _check_file(ti);