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, 4 insertions, 4 deletions

diff --git a/fs/ubifs/recovery.c b/fs/ubifs/recovery.c
index daae9e1f5382..c902a5de90ae 100644
--- a/fs/ubifs/recovery.c
+++ b/fs/ubifs/recovery.c
@@ -292,7 +292,7 @@ int ubifs_recover_master_node(struct ubifs_info *c)
 
         memcpy(c->mst_node, mst, UBIFS_MST_NODE_SZ);
 
-        if ((c->vfs_sb->s_flags & MS_RDONLY)) {
+        if (c->ro_mount) {
                 /* Read-only mode. Keep a copy for switching to rw mode */
                 c->rcvrd_mst_node = kmalloc(sz, GFP_KERNEL);
                 if (!c->rcvrd_mst_node) {
@@ -469,7 +469,7 @@ static int fix_unclean_leb(struct ubifs_info *c, struct ubifs_scan_leb *sleb,
                 endpt = snod->offs + snod->len;
         }
 
-        if ((c->vfs_sb->s_flags & MS_RDONLY) && !c->remounting_rw) {
+        if (c->ro_mount && !c->remounting_rw) {
                 /* Add to recovery list */
                 struct ubifs_unclean_leb *ucleb;
 
@@ -883,7 +883,7 @@ int ubifs_recover_inl_heads(const struct ubifs_info *c, void *sbuf)
 {
         int err;
 
-        ubifs_assert(!(c->vfs_sb->s_flags & MS_RDONLY) || c->remounting_rw);
+        ubifs_assert(!c->ro_mount || c->remounting_rw);
 
         dbg_rcvry("checking index head at %d:%d", c->ihead_lnum, c->ihead_offs);
         err = recover_head(c, c->ihead_lnum, c->ihead_offs, sbuf);
@@ -1461,7 +1461,7 @@ int ubifs_recover_size(struct ubifs_info *c)
                         }
                 }
                 if (e->exists && e->i_size < e->d_size) {
-                        if (!e->inode && (c->vfs_sb->s_flags & MS_RDONLY)) {
+                        if (!e->inode && c->ro_mount) {
                                 /* Fix the inode size and pin it in memory */
                                 struct inode *inode;