From 26c4c170731f00008f4317a2888a0a07ac99d90d Mon Sep 17 00:00:00 2001 From: Jeff Layton Date: Wed, 27 Apr 2011 11:49:09 -0400 Subject: [PATCH] nfs: don't lose MS_SYNCHRONOUS on remount of noac mount On a remount, the VFS layer will clear the MS_SYNCHRONOUS bit on the assumption that the flags on the mount syscall will have it set if the remounted fs is supposed to keep it. In the case of "noac" though, MS_SYNCHRONOUS is implied. A remount of such a mount will lose the MS_SYNCHRONOUS flag since "sync" isn't part of the mount options. Reported-by: Max Matveev Signed-off-by: Jeff Layton Cc: stable@kernel.org Signed-off-by: Trond Myklebust --- fs/nfs/super.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/fs/nfs/super.c b/fs/nfs/super.c index 75bcc3f0e0b5..e288f06d3fa7 100644 --- a/fs/nfs/super.c +++ b/fs/nfs/super.c @@ -1977,6 +1977,15 @@ nfs_remount(struct super_block *sb, int *flags, char *raw_data) if (error < 0) goto out; + /* + * noac is a special case. It implies -o sync, but that's not + * necessarily reflected in the mtab options. do_remount_sb + * will clear MS_SYNCHRONOUS if -o sync wasn't specified in the + * remount options, so we have to explicitly reset it. + */ + if (data->flags & NFS_MOUNT_NOAC) + *flags |= MS_SYNCHRONOUS; + /* compare new mount options with old ones */ error = nfs_compare_remount_data(nfss, data); out: