GFS2: Add some useful messages

The following patch adds a message to indicate when barriers have been
disabled due to a block device which doesn't support them. You could
already tell this via the mount options in /proc/mounts, but all the
other filesystems also log a message at the same time.

Also, the same mechanisms are used to indicate when the lock
demote interface has been used (only ever used for debugging)
which is a request from our support team.

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

4 files changed, 6 insertions, 1 deletions

diff --git a/fs/gfs2/incore.h b/fs/gfs2/incore.h
index 08dd6574547..b5d7363b22d 100644
--- a/fs/gfs2/incore.h
+++ b/fs/gfs2/incore.h
@@ -459,6 +459,7 @@ enum {
         SDF_SHUTDOWN            = 2,
         SDF_NOBARRIERS          = 3,
         SDF_NORECOVERY          = 4,
+        SDF_DEMOTE              = 5,
 };
 
 #define GFS2_FSNAME_LEN         256
diff --git a/fs/gfs2/log.c b/fs/gfs2/log.c
index d5959df6deb..b593f0e28f2 100644
--- a/fs/gfs2/log.c
+++ b/fs/gfs2/log.c
@@ -600,6 +600,7 @@ static void log_write_header(struct gfs2_sbd *sdp, u32 flags, int pull)
         if (buffer_eopnotsupp(bh)) {
                 clear_buffer_eopnotsupp(bh);
                 set_buffer_uptodate(bh);
+                fs_info(sdp, "barrier sync failed - disabling barriers\n");
                 set_bit(SDF_NOBARRIERS, &sdp->sd_flags);
                 lock_buffer(bh);
 skip_barrier:
diff --git a/fs/gfs2/super.c b/fs/gfs2/super.c
index 7a93e9ff7d3..4d1aad38f1b 100644
--- a/fs/gfs2/super.c
+++ b/fs/gfs2/super.c
@@ -1334,7 +1334,8 @@ static int gfs2_show_options(struct seq_file *s, struct vfsmount *mnt)
         }
         if (test_bit(SDF_NOBARRIERS, &sdp->sd_flags))
                 seq_printf(s, ",nobarrier");
-
+        if (test_bit(SDF_DEMOTE, &sdp->sd_flags))
+                seq_printf(s, ",demote_interface_used");
         return 0;
 }
 
diff --git a/fs/gfs2/sys.c b/fs/gfs2/sys.c
index 2ac845d9c46..7afb62ec97c 100644
--- a/fs/gfs2/sys.c
+++ b/fs/gfs2/sys.c
@@ -233,6 +233,8 @@ static ssize_t demote_rq_store(struct gfs2_sbd *sdp, const char *buf, size_t len
         glops = gfs2_glops_list[gltype];
         if (glops == NULL)
                 return -EINVAL;
+        if (test_and_set_bit(SDF_DEMOTE, &sdp->sd_flags))
+                fs_info(sdp, "demote interface used\n");
         rv = gfs2_glock_get(sdp, glnum, glops, 0, &gl);
         if (rv)
                 return rv;