UBIFS: introduce new flags for RO mounts

Commit 2fde99cb55fb9d9b88180512a5e8a5d939d27fec "UBIFS: mark VFS SB RO too"
introduced regression. This commit made UBIFS set the 'MS_RDONLY' flag in the
VFS superblock when it switches to R/O mode due to an error. This was done
to make VFS show the R/O UBIFS flag in /proc/mounts.

However, several places in UBIFS relied on the 'MS_RDONLY' flag and assume this
flag can only change when we re-mount. For example, 'ubifs_put_super()'.

This patch introduces new UBIFS flag - 'c->ro_mount' which changes only when
we re-mount, and preserves the way UBIFS was originally mounted (R/W or R/O).
This allows us to de-initialize UBIFS cleanly in 'ubifs_put_super()'.

This patch also changes all 'ubifs_assert(!c->ro_media)' assertions to
'ubifs_assert(!c->ro_media && !c->ro_mount)', because we never should write
anything if the FS was mounter R/O.

All the places where we test for 'MS_RDONLY' flag in the VFS SB were changed
and now we test the 'c->ro_mount' flag instead, because it preserves the
original UBIFS mount type, unlike the 'MS_RDONLY' flag.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/fs/ubifs/log.c b/fs/ubifs/log.c
index a41713e2fbb3..4d0cb1241460 100644
--- a/fs/ubifs/log.c
+++ b/fs/ubifs/log.c
@@ -159,7 +159,7 @@ void ubifs_add_bud(struct ubifs_info *c, struct ubifs_bud *bud)
 		jhead = &c->jheads[bud->jhead];
 		list_add_tail(&bud->list, &jhead->buds_list);
 	} else
-		ubifs_assert(c->replaying && (c->vfs_sb->s_flags & MS_RDONLY));
+		ubifs_assert(c->replaying && c->ro_mount);
 
 	/*
 	 * Note, although this is a new bud, we anyway account this space now,
@@ -223,7 +223,7 @@ int ubifs_add_bud_to_log(struct ubifs_info *c, int jhead, int lnum, int offs)
 	}
 
 	mutex_lock(&c->log_mutex);
-	ubifs_assert(!c->ro_media);
+	ubifs_assert(!c->ro_media && !c->ro_mount);
 	if (c->ro_error) {
 		err = -EROFS;
 		goto out_unlock;