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, 1 insertions, 1 deletions

diff --git a/fs/ubifs/shrinker.c b/fs/ubifs/shrinker.c
index 10eec8778438..46961c003236 100644
--- a/fs/ubifs/shrinker.c
+++ b/fs/ubifs/shrinker.c
@@ -250,7 +250,7 @@ static int kick_a_thread(void)
                         dirty_zn_cnt = atomic_long_read(&c->dirty_zn_cnt);
 
                         if (!dirty_zn_cnt || c->cmt_state == COMMIT_BROKEN ||
-                            c->ro_media || c->ro_error) {
+                            c->ro_mount || c->ro_error) {
                                 mutex_unlock(&c->umount_mutex);
                                 continue;
                         }