[GFS2] Allow journal recovery on read-only mount

This patch allows gfs2 to perform journal recovery even if it is mounted
read-only. Strictly speaking, a read-only mount should not be writing to
the filesystem, but we do this only to perform journal recovery. A
read-only mount will fail if we don't recover the dirty journal. Also,
when gfs2 is used as a root filesystem, it will be mounted read-only
before being mounted read-write during the boot sequence. A failed
read-only mount will panic the machine during bootup.

Signed-off-by: Abhijith Das <adas@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

1 files changed, 12 insertions, 4 deletions

diff --git a/fs/gfs2/recovery.c b/fs/gfs2/recovery.c
index 27c994f2d1f0..b249e294a95b 100644
--- a/fs/gfs2/recovery.c
+++ b/fs/gfs2/recovery.c
@@ -504,13 +504,21 @@ int gfs2_recover_journal(struct gfs2_jdesc *jd)
                         if (!test_bit(SDF_JOURNAL_LIVE, &sdp->sd_flags))
                                 ro = 1;
                 } else {
-                        if (sdp->sd_vfs->s_flags & MS_RDONLY)
-                                ro = 1;
+                        if (sdp->sd_vfs->s_flags & MS_RDONLY) {
+                                /* check if device itself is read-only */
+                                ro = bdev_read_only(sdp->sd_vfs->s_bdev);
+                                if (!ro) {
+                                        fs_info(sdp, "recovery required on "
+                                                "read-only filesystem.\n");
+                                        fs_info(sdp, "write access will be "
+                                                "enabled during recovery.\n");
+                                }
+                        }
                 }
 
                 if (ro) {
-                        fs_warn(sdp, "jid=%u: Can't replay: read-only FS\n",
-                                jd->jd_jid);
+                        fs_warn(sdp, "jid=%u: Can't replay: read-only block "
+                                "device\n", jd->jd_jid);
                         error = -EROFS;
                         goto fail_gunlock_tr;
                 }