xfs: check the realtime superblock at mount time

Check the realtime superblock at mount time, to ensure that the label
actually matches the primary superblock.  If the rt superblock is good,
attach it to the xfs_mount so that the log can use ordered buffers to
keep this primary in sync with the primary super on the data device.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>

4 files changed, 70 insertions, 2 deletions

diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h
index 674938008a97..7f0a80a8dcd4 100644
--- a/fs/xfs/xfs_mount.h
+++ b/fs/xfs/xfs_mount.h
@@ -82,6 +82,7 @@ typedef struct xfs_mount {
 	struct super_block	*m_super;
 	struct xfs_ail		*m_ail;		/* fs active log item list */
 	struct xfs_buf		*m_sb_bp;	/* buffer for superblock */
+	struct xfs_buf		*m_rtsb_bp;	/* realtime superblock */
 	char			*m_rtname;	/* realtime device name */
 	char			*m_logname;	/* external log device name */
 	struct xfs_da_geometry	*m_dir_geo;	/* directory block geometry */
diff --git a/fs/xfs/xfs_rtalloc.c b/fs/xfs/xfs_rtalloc.c
index 3b13352cfbfc..9c842237c452 100644
--- a/fs/xfs/xfs_rtalloc.c
+++ b/fs/xfs/xfs_rtalloc.c
@@ -1263,6 +1263,56 @@ retry:
 	return 0;
 }
 
+/* Read the primary realtime group's superblock and attach it to the mount. */
+int
+xfs_rtmount_readsb(
+	struct xfs_mount	*mp)
+{
+	struct xfs_buf		*bp;
+	int			error;
+
+	if (!xfs_has_rtgroups(mp))
+		return 0;
+	if (mp->m_sb.sb_rblocks == 0)
+		return 0;
+	if (mp->m_rtdev_targp == NULL) {
+		xfs_warn(mp,
+	"Filesystem has a realtime volume, use rtdev=device option");
+		return -ENODEV;
+	}
+
+	/* m_blkbb_log is not set up yet */
+	error = xfs_buf_read_uncached(mp->m_rtdev_targp, XFS_RTSB_DADDR,
+			mp->m_sb.sb_blocksize >> BBSHIFT, XBF_NO_IOACCT, &bp,
+			&xfs_rtsb_buf_ops);
+	if (error) {
+		xfs_warn(mp, "rt sb validate failed with error %d.", error);
+		/* bad CRC means corrupted metadata */
+		if (error == -EFSBADCRC)
+			error = -EFSCORRUPTED;
+		return error;
+	}
+
+	mp->m_rtsb_bp = bp;
+	xfs_buf_unlock(bp);
+	return 0;
+}
+
+/* Detach the realtime superblock from the mount and free it. */
+void
+xfs_rtmount_freesb(
+	struct xfs_mount	*mp)
+{
+	struct xfs_buf		*bp = mp->m_rtsb_bp;
+
+	if (!bp)
+		return;
+
+	xfs_buf_lock(bp);
+	mp->m_rtsb_bp = NULL;
+	xfs_buf_relse(bp);
+}
+
 /*
  * Initialize realtime fields in the mount structure.
  */
diff --git a/fs/xfs/xfs_rtalloc.h b/fs/xfs/xfs_rtalloc.h
index 5ac9c15948c8..d0fd49db77bd 100644
--- a/fs/xfs/xfs_rtalloc.h
+++ b/fs/xfs/xfs_rtalloc.h
@@ -33,6 +33,9 @@ xfs_rtallocate_extent(
 	xfs_rtxnum_t		*rtblock); /* out: start rtext allocated */
 
 
+int xfs_rtmount_readsb(struct xfs_mount *mp);
+void xfs_rtmount_freesb(struct xfs_mount *mp);
+
 /*
  * Initialize realtime fields in the mount structure.
  */
@@ -81,6 +84,8 @@ int xfs_rtfile_convert_unwritten(struct xfs_inode *ip, loff_t pos,
 # define xfs_rtpick_extent(m,t,l,rb)			(-ENOSYS)
 # define xfs_growfs_rt(mp,in)				(-ENOSYS)
 # define xfs_rtalloc_reinit_frextents(m)		(0)
+# define xfs_rtmount_readsb(mp)				(0)
+# define xfs_rtmount_freesb(mp)				((void)0)
 static inline int		/* error */
 xfs_rtmount_init(
 	xfs_mount_t	*mp)	/* file system mount structure */
diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
index f13ab39212d2..68c41a904652 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -43,6 +43,7 @@
 #include "xfs_iunlink_item.h"
 #include "xfs_swapext_item.h"
 #include "xfs_rtbitmap.h"
+#include "xfs_rtalloc.h"
 
 #include <linux/magic.h>
 #include <linux/fs_context.h>
@@ -1116,6 +1117,7 @@ xfs_fs_put_super(
 	xfs_filestream_unmount(mp);
 	xfs_unmountfs(mp);
 
+	xfs_rtmount_freesb(mp);
 	xfs_freesb(mp);
 	free_percpu(mp->m_stats.xs_stats);
 	xfs_mount_list_del(mp);
@@ -1598,10 +1600,14 @@ xfs_fs_fill_super(
 		goto out_free_sb;
 	}
 
-	error = xfs_filestream_mount(mp);
+	error = xfs_rtmount_readsb(mp);
 	if (error)
 		goto out_free_sb;
 
+	error = xfs_filestream_mount(mp);
+	if (error)
+		goto out_free_rtsb;
+
 	/*
 	 * we must configure the block size in the superblock before we run the
 	 * full mount process as the mount process can lookup and cache inodes.
@@ -1644,6 +1650,10 @@ xfs_fs_fill_super(
 		xfs_warn(mp,
 "EXPERIMENTAL metadata directory feature in use. Use at your own risk!");
 
+	if (xfs_has_rtgroups(mp))
+		xfs_warn(mp,
+"EXPERIMENTAL realtime allocation group feature in use. Use at your own risk!");
+
 	if (xfs_has_reflink(mp)) {
 		if (mp->m_sb.sb_rblocks) {
 			xfs_alert(mp,
@@ -1688,6 +1698,8 @@ xfs_fs_fill_super(
 
  out_filestream_unmount:
 	xfs_filestream_unmount(mp);
+ out_free_rtsb:
+	xfs_rtmount_freesb(mp);
  out_free_sb:
 	xfs_freesb(mp);
  out_free_stats:
@@ -1709,7 +1721,7 @@ xfs_fs_fill_super(
  out_unmount:
 	xfs_filestream_unmount(mp);
 	xfs_unmountfs(mp);
-	goto out_free_sb;
+	goto out_free_rtsb;
 }
 
 static int