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>

14 files changed, 62 insertions, 60 deletions

diff --git a/fs/ubifs/commit.c b/fs/ubifs/commit.c
index 712432789fb8..02429d81ca33 100644
--- a/fs/ubifs/commit.c
+++ b/fs/ubifs/commit.c
@@ -63,7 +63,7 @@ static int do_commit(struct ubifs_info *c)
         struct ubifs_lp_stats lst;
 
         dbg_cmt("start");
-        ubifs_assert(!c->ro_media);
+        ubifs_assert(!c->ro_media && !c->ro_mount);
 
         if (c->ro_error) {
                 err = -EROFS;
diff --git a/fs/ubifs/file.c b/fs/ubifs/file.c
index c6bc51c9f07c..d77db7e36484 100644
--- a/fs/ubifs/file.c
+++ b/fs/ubifs/file.c
@@ -433,7 +433,7 @@ static int ubifs_write_begin(struct file *file, struct address_space *mapping,
         struct page *page;
 
         ubifs_assert(ubifs_inode(inode)->ui_size == inode->i_size);
-        ubifs_assert(!c->ro_media);
+        ubifs_assert(!c->ro_media && !c->ro_mount);
 
         if (unlikely(c->ro_error))
                 return -EROFS;
@@ -1440,8 +1440,7 @@ static int ubifs_vm_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vm
 
         dbg_gen("ino %lu, pg %lu, i_size %lld", inode->i_ino, page->index,
                 i_size_read(inode));
-        ubifs_assert(!(inode->i_sb->s_flags & MS_RDONLY));
-        ubifs_assert(!c->ro_media);
+        ubifs_assert(!c->ro_media && !c->ro_mount);
 
         if (unlikely(c->ro_error))
                 return VM_FAULT_SIGBUS; /* -EROFS */
diff --git a/fs/ubifs/gc.c b/fs/ubifs/gc.c
index d927196d730b..151f10882820 100644
--- a/fs/ubifs/gc.c
+++ b/fs/ubifs/gc.c
@@ -616,7 +616,7 @@ int ubifs_garbage_collect(struct ubifs_info *c, int anyway)
         struct ubifs_wbuf *wbuf = &c->jheads[GCHD].wbuf;
 
         ubifs_assert_cmt_locked(c);
-        ubifs_assert(!c->ro_media);
+        ubifs_assert(!c->ro_media && !c->ro_mount);
 
         if (ubifs_gc_should_commit(c))
                 return -EAGAIN;
diff --git a/fs/ubifs/io.c b/fs/ubifs/io.c
index 18a4b8d7c844..d82173182eeb 100644
--- a/fs/ubifs/io.c
+++ b/fs/ubifs/io.c
@@ -356,10 +356,9 @@ int ubifs_wbuf_sync_nolock(struct ubifs_wbuf *wbuf)
 
         dbg_io("LEB %d:%d, %d bytes, jhead %s",
                wbuf->lnum, wbuf->offs, wbuf->used, dbg_jhead(wbuf->jhead));
-        ubifs_assert(!(c->vfs_sb->s_flags & MS_RDONLY));
         ubifs_assert(!(wbuf->avail & 7));
         ubifs_assert(wbuf->offs + c->min_io_size <= c->leb_size);
-        ubifs_assert(!c->ro_media);
+        ubifs_assert(!c->ro_media && !c->ro_mount);
 
         if (c->ro_error)
                 return -EROFS;
@@ -441,7 +440,7 @@ int ubifs_bg_wbufs_sync(struct ubifs_info *c)
 {
         int err, i;
 
-        ubifs_assert(!c->ro_media);
+        ubifs_assert(!c->ro_media && !c->ro_mount);
         if (!c->need_wbuf_sync)
                 return 0;
         c->need_wbuf_sync = 0;
@@ -521,7 +520,7 @@ int ubifs_wbuf_write_nolock(struct ubifs_wbuf *wbuf, void *buf, int len)
         ubifs_assert(!(wbuf->offs & 7) && wbuf->offs <= c->leb_size);
         ubifs_assert(wbuf->avail > 0 && wbuf->avail <= c->min_io_size);
         ubifs_assert(mutex_is_locked(&wbuf->io_mutex));
-        ubifs_assert(!c->ro_media);
+        ubifs_assert(!c->ro_media && !c->ro_mount);
 
         if (c->leb_size - wbuf->offs - wbuf->used < aligned_len) {
                 err = -ENOSPC;
@@ -666,7 +665,7 @@ int ubifs_write_node(struct ubifs_info *c, void *buf, int len, int lnum,
                buf_len);
         ubifs_assert(lnum >= 0 && lnum < c->leb_cnt && offs >= 0);
         ubifs_assert(offs % c->min_io_size == 0 && offs < c->leb_size);
-        ubifs_assert(!c->ro_media);
+        ubifs_assert(!c->ro_media && !c->ro_mount);
 
         if (c->ro_error)
                 return -EROFS;
diff --git a/fs/ubifs/journal.c b/fs/ubifs/journal.c
index a6da8aa68f37..914f1bd89e57 100644
--- a/fs/ubifs/journal.c
+++ b/fs/ubifs/journal.c
@@ -122,7 +122,7 @@ static int reserve_space(struct ubifs_info *c, int jhead, int len)
          * better to try to allocate space at the ends of eraseblocks. This is
          * what the squeeze parameter does.
          */
-        ubifs_assert(!c->ro_media);
+        ubifs_assert(!c->ro_media && !c->ro_mount);
         squeeze = (jhead == BASEHD);
 again:
         mutex_lock_nested(&wbuf->io_mutex, wbuf->jhead);
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;
diff --git a/fs/ubifs/master.c b/fs/ubifs/master.c
index 0c818e855f59..21f47afdacff 100644
--- a/fs/ubifs/master.c
+++ b/fs/ubifs/master.c
@@ -361,7 +361,7 @@ int ubifs_write_master(struct ubifs_info *c)
 {
         int err, lnum, offs, len;
 
-        ubifs_assert(!c->ro_media);
+        ubifs_assert(!c->ro_media && !c->ro_mount);
         if (c->ro_error)
                 return -EROFS;
 
diff --git a/fs/ubifs/misc.h b/fs/ubifs/misc.h
index 5d476ba184e6..c3de04dc952a 100644
--- a/fs/ubifs/misc.h
+++ b/fs/ubifs/misc.h
@@ -132,7 +132,7 @@ static inline int ubifs_leb_unmap(const struct ubifs_info *c, int lnum)
 {
         int err;
 
-        ubifs_assert(!c->ro_media);
+        ubifs_assert(!c->ro_media && !c->ro_mount);
         if (c->ro_error)
                 return -EROFS;
         err = ubi_leb_unmap(c->ubi, lnum);
@@ -160,7 +160,7 @@ static inline int ubifs_leb_write(const struct ubifs_info *c, int lnum,
 {
         int err;
 
-        ubifs_assert(!c->ro_media);
+        ubifs_assert(!c->ro_media && !c->ro_mount);
         if (c->ro_error)
                 return -EROFS;
         err = ubi_leb_write(c->ubi, lnum, buf, offs, len, dtype);
@@ -188,7 +188,7 @@ static inline int ubifs_leb_change(const struct ubifs_info *c, int lnum,
 {
         int err;
 
-        ubifs_assert(!c->ro_media);
+        ubifs_assert(!c->ro_media && !c->ro_mount);
         if (c->ro_error)
                 return -EROFS;
         err = ubi_leb_change(c->ubi, lnum, buf, len, dtype);
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;
 
diff --git a/fs/ubifs/replay.c b/fs/ubifs/replay.c
index 5c2d6d759a3e..730598cf6342 100644
--- a/fs/ubifs/replay.c
+++ b/fs/ubifs/replay.c
@@ -627,8 +627,7 @@ static int replay_bud(struct ubifs_info *c, int lnum, int offs, int jhead,
         ubifs_assert(sleb->endpt - offs >= used);
         ubifs_assert(sleb->endpt % c->min_io_size == 0);
 
-        if (sleb->endpt + c->min_io_size <= c->leb_size &&
-            !(c->vfs_sb->s_flags & MS_RDONLY))
+        if (sleb->endpt + c->min_io_size <= c->leb_size && !c->ro_mount)
                 err = ubifs_wbuf_seek_nolock(&c->jheads[jhead].wbuf, lnum,
                                              sleb->endpt, UBI_SHORTTERM);
 
diff --git a/fs/ubifs/sb.c b/fs/ubifs/sb.c
index 96cb62c8a9dd..bf31b4729e51 100644
--- a/fs/ubifs/sb.c
+++ b/fs/ubifs/sb.c
@@ -542,11 +542,8 @@ int ubifs_read_superblock(struct ubifs_info *c)
          * due to the unavailability of time-travelling equipment.
          */
         if (c->fmt_version > UBIFS_FORMAT_VERSION) {
-                struct super_block *sb = c->vfs_sb;
-                int mounting_ro = sb->s_flags & MS_RDONLY;
-
-                ubifs_assert(!c->ro_media || mounting_ro);
-                if (!mounting_ro ||
+                ubifs_assert(!c->ro_media || c->ro_mount);
+                if (!c->ro_mount ||
                     c->ro_compat_version > UBIFS_RO_COMPAT_VERSION) {
                         ubifs_err("on-flash format version is w%d/r%d, but "
                                   "software only supports up to version "
@@ -624,7 +621,7 @@ int ubifs_read_superblock(struct ubifs_info *c)
         c->old_leb_cnt = c->leb_cnt;
         if (c->leb_cnt < c->vi.size && c->leb_cnt < c->max_leb_cnt) {
                 c->leb_cnt = min_t(int, c->max_leb_cnt, c->vi.size);
-                if (c->vfs_sb->s_flags & MS_RDONLY)
+                if (c->ro_mount)
                         dbg_mnt("Auto resizing (ro) from %d LEBs to %d LEBs",
                                 c->old_leb_cnt, c->leb_cnt);
                 else {
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;
                         }
diff --git a/fs/ubifs/super.c b/fs/ubifs/super.c
index 1cfeec56df91..4e5bf3fbf782 100644
--- a/fs/ubifs/super.c
+++ b/fs/ubifs/super.c
@@ -1137,11 +1137,11 @@ static int check_free_space(struct ubifs_info *c)
  */
 static int mount_ubifs(struct ubifs_info *c)
 {
-        struct super_block *sb = c->vfs_sb;
-        int err, mounted_read_only = (sb->s_flags & MS_RDONLY);
+        int err;
         long long x;
         size_t sz;
 
+        c->ro_mount = !!(c->vfs_sb->s_flags & MS_RDONLY);
         err = init_constants_early(c);
         if (err)
                 return err;
@@ -1154,7 +1154,7 @@ static int mount_ubifs(struct ubifs_info *c)
         if (err)
                 goto out_free;
 
-        if (c->empty && (mounted_read_only || c->ro_media)) {
+        if (c->empty && (c->ro_mount || c->ro_media)) {
                 /*
                  * This UBI volume is empty, and read-only, or the file system
                  * is mounted read-only - we cannot format it.
@@ -1165,7 +1165,7 @@ static int mount_ubifs(struct ubifs_info *c)
                 goto out_free;
         }
 
-        if (c->ro_media && !mounted_read_only) {
+        if (c->ro_media && !c->ro_mount) {
                 ubifs_err("cannot mount read-write - read-only media");
                 err = -EROFS;
                 goto out_free;
@@ -1185,7 +1185,7 @@ static int mount_ubifs(struct ubifs_info *c)
         if (!c->sbuf)
                 goto out_free;
 
-        if (!mounted_read_only) {
+        if (!c->ro_mount) {
                 c->ileb_buf = vmalloc(c->leb_size);
                 if (!c->ileb_buf)
                         goto out_free;
@@ -1228,7 +1228,7 @@ static int mount_ubifs(struct ubifs_info *c)
         }
 
         sprintf(c->bgt_name, BGT_NAME_PATTERN, c->vi.ubi_num, c->vi.vol_id);
-        if (!mounted_read_only) {
+        if (!c->ro_mount) {
                 err = alloc_wbufs(c);
                 if (err)
                         goto out_cbuf;
@@ -1254,12 +1254,12 @@ static int mount_ubifs(struct ubifs_info *c)
         if ((c->mst_node->flags & cpu_to_le32(UBIFS_MST_DIRTY)) != 0) {
                 ubifs_msg("recovery needed");
                 c->need_recovery = 1;
-                if (!mounted_read_only) {
+                if (!c->ro_mount) {
                         err = ubifs_recover_inl_heads(c, c->sbuf);
                         if (err)
                                 goto out_master;
                 }
-        } else if (!mounted_read_only) {
+        } else if (!c->ro_mount) {
                 /*
                  * Set the "dirty" flag so that if we reboot uncleanly we
                  * will notice this immediately on the next mount.
@@ -1270,7 +1270,7 @@ static int mount_ubifs(struct ubifs_info *c)
                         goto out_master;
         }
 
-        err = ubifs_lpt_init(c, 1, !mounted_read_only);
+        err = ubifs_lpt_init(c, 1, !c->ro_mount);
         if (err)
                 goto out_lpt;
 
@@ -1285,11 +1285,11 @@ static int mount_ubifs(struct ubifs_info *c)
         /* Calculate 'min_idx_lebs' after journal replay */
         c->min_idx_lebs = ubifs_calc_min_idx_lebs(c);
 
-        err = ubifs_mount_orphans(c, c->need_recovery, mounted_read_only);
+        err = ubifs_mount_orphans(c, c->need_recovery, c->ro_mount);
         if (err)
                 goto out_orphans;
 
-        if (!mounted_read_only) {
+        if (!c->ro_mount) {
                 int lnum;
 
                 err = check_free_space(c);
@@ -1351,7 +1351,7 @@ static int mount_ubifs(struct ubifs_info *c)
         spin_unlock(&ubifs_infos_lock);
 
         if (c->need_recovery) {
-                if (mounted_read_only)
+                if (c->ro_mount)
                         ubifs_msg("recovery deferred");
                 else {
                         c->need_recovery = 0;
@@ -1378,7 +1378,7 @@ static int mount_ubifs(struct ubifs_info *c)
 
         ubifs_msg("mounted UBI device %d, volume %d, name \"%s\"",
                   c->vi.ubi_num, c->vi.vol_id, c->vi.name);
-        if (mounted_read_only)
+        if (c->ro_mount)
                 ubifs_msg("mounted read-only");
         x = (long long)c->main_lebs * c->leb_size;
         ubifs_msg("file system size:   %lld bytes (%lld KiB, %lld MiB, %d "
@@ -1640,7 +1640,7 @@ static int ubifs_remount_rw(struct ubifs_info *c)
         }
 
         dbg_gen("re-mounted read-write");
-        c->vfs_sb->s_flags &= ~MS_RDONLY;
+        c->ro_mount = 0;
         c->remounting_rw = 0;
         c->always_chk_crc = 0;
         err = dbg_check_space_info(c);
@@ -1676,7 +1676,7 @@ static void ubifs_remount_ro(struct ubifs_info *c)
         int i, err;
 
         ubifs_assert(!c->need_recovery);
-        ubifs_assert(!(c->vfs_sb->s_flags & MS_RDONLY));
+        ubifs_assert(!c->ro_mount);
 
         mutex_lock(&c->umount_mutex);
         if (c->bgt) {
@@ -1704,6 +1704,7 @@ static void ubifs_remount_ro(struct ubifs_info *c)
         vfree(c->ileb_buf);
         c->ileb_buf = NULL;
         ubifs_lpt_free(c, 1);
+        c->ro_mount = 1;
         err = dbg_check_space_info(c);
         if (err)
                 ubifs_ro_mode(c, err);
@@ -1735,7 +1736,7 @@ static void ubifs_put_super(struct super_block *sb)
          * the mutex is locked.
          */
         mutex_lock(&c->umount_mutex);
-        if (!(c->vfs_sb->s_flags & MS_RDONLY)) {
+        if (!c->ro_mount) {
                 /*
                  * First of all kill the background thread to make sure it does
                  * not interfere with un-mounting and freeing resources.
@@ -1745,23 +1746,23 @@ static void ubifs_put_super(struct super_block *sb)
                         c->bgt = NULL;
                 }
 
-                /* Synchronize write-buffers */
-                if (c->jheads)
-                        for (i = 0; i < c->jhead_cnt; i++)
-                                ubifs_wbuf_sync(&c->jheads[i].wbuf);
-
                 /*
                  * On fatal errors c->ro_error is set to 1, in which case we do
                  * not write the master node.
                  */
                 if (!c->ro_error) {
+                        int err;
+
+                        /* Synchronize write-buffers */
+                        if (c->jheads)
+                                for (i = 0; i < c->jhead_cnt; i++)
+                                        ubifs_wbuf_sync(&c->jheads[i].wbuf);
+
                         /*
                          * We are being cleanly unmounted which means the
                          * orphans were killed - indicate this in the master
                          * node. Also save the reserved GC LEB number.
                          */
-                        int err;
-
                         c->mst_node->flags &= ~cpu_to_le32(UBIFS_MST_DIRTY);
                         c->mst_node->flags |= cpu_to_le32(UBIFS_MST_NO_ORPHS);
                         c->mst_node->gc_lnum = cpu_to_le32(c->gc_lnum);
@@ -1797,7 +1798,7 @@ static int ubifs_remount_fs(struct super_block *sb, int *flags, char *data)
                 return err;
         }
 
-        if ((sb->s_flags & MS_RDONLY) && !(*flags & MS_RDONLY)) {
+        if (c->ro_mount && !(*flags & MS_RDONLY)) {
                 if (c->ro_error) {
                         ubifs_msg("cannot re-mount R/W due to prior errors");
                         return -EROFS;
@@ -1809,7 +1810,7 @@ static int ubifs_remount_fs(struct super_block *sb, int *flags, char *data)
                 err = ubifs_remount_rw(c);
                 if (err)
                         return err;
-        } else if (!(sb->s_flags & MS_RDONLY) && (*flags & MS_RDONLY)) {
+        } else if (!c->ro_mount && (*flags & MS_RDONLY)) {
                 if (c->ro_error) {
                         ubifs_msg("cannot re-mount R/O due to prior errors");
                         return -EROFS;
@@ -2068,9 +2069,11 @@ static int ubifs_get_sb(struct file_system_type *fs_type, int flags,
         }
 
         if (sb->s_root) {
+                struct ubifs_info *c1 = sb->s_fs_info;
+
                 /* A new mount point for already mounted UBIFS */
                 dbg_gen("this ubi volume is already mounted");
-                if ((flags ^ sb->s_flags) & MS_RDONLY) {
+                if (!!(flags & MS_RDONLY) != c1->ro_mount) {
                         err = -EBUSY;
                         goto out_deact;
                 }
diff --git a/fs/ubifs/ubifs.h b/fs/ubifs/ubifs.h
index f47ebb442d1c..381d6b207a52 100644
--- a/fs/ubifs/ubifs.h
+++ b/fs/ubifs/ubifs.h
@@ -1032,6 +1032,7 @@ struct ubifs_debug_info;
  * @max_leb_cnt: maximum count of logical eraseblocks
  * @old_leb_cnt: count of logical eraseblocks before re-size
  * @ro_media: the underlying UBI volume is read-only
+ * @ro_mount: the file-system was mounted as read-only
  * @ro_error: UBIFS switched to R/O mode because an error happened
  *
  * @dirty_pg_cnt: number of dirty pages (not used)
@@ -1173,11 +1174,14 @@ struct ubifs_debug_info;
  * @replay_sqnum: sequence number of node currently being replayed
  * @need_recovery: file-system needs recovery
  * @replaying: set to %1 during journal replay
- * @unclean_leb_list: LEBs to recover when mounting ro to rw
- * @rcvrd_mst_node: recovered master node to write when mounting ro to rw
+ * @unclean_leb_list: LEBs to recover when re-mounting R/O mounted FS to R/W
+ *                    mode
+ * @rcvrd_mst_node: recovered master node to write when re-mounting R/O mounted
+ *                  FS to R/W mode
  * @size_tree: inode size information for recovery
- * @remounting_rw: set while remounting from ro to rw (sb flags have MS_RDONLY)
- * @always_chk_crc: always check CRCs (while mounting and remounting rw)
+ * @remounting_rw: set while re-mounting from R/O mode to R/W mode
+ * @always_chk_crc: always check CRCs (while mounting and remounting to R/W
+ *                  mode)
  * @mount_opts: UBIFS-specific mount options
  *
  * @dbg: debugging-related information
@@ -1274,6 +1278,7 @@ struct ubifs_info {
         int max_leb_cnt;
         int old_leb_cnt;
         unsigned int ro_media:1;
+        unsigned int ro_mount:1;
         unsigned int ro_error:1;
 
         atomic_long_t dirty_pg_cnt;