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, 5 deletions

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;