[GFS2] Add gfs2meta filesystem

In order to separate out the filesystem's metadata from "normal"
files and directories, a new filesystem type has been created.
It is called gfs2meta and mounting it gives access to the files
that were previously under .gfs2_admin (well still are until mkfs
is altered, which is next on the adgenda).

Its not currently possible to mount both gfs2 and gfs2meta on the
same block device at the same time. A future patch will allow that
to happen.

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

3 files changed, 45 insertions, 23 deletions

diff --git a/fs/gfs2/main.c b/fs/gfs2/main.c
index c541777..c8d17b7 100644
--- a/fs/gfs2/main.c
+++ b/fs/gfs2/main.c
@@ -64,11 +64,17 @@ static int __init init_gfs2_fs(void)
 	if (error)
 		goto fail;
 
+	error = register_filesystem(&gfs2meta_fs_type);
+	if (error)
+		goto fail_unregister;
+
 	printk("GFS2 (built %s %s) installed\n", __DATE__, __TIME__);
 
 	return 0;
 
- fail:
+fail_unregister:
+	unregister_filesystem(&gfs2_fs_type);
+fail:
 	if (gfs2_bufdata_cachep)
 		kmem_cache_destroy(gfs2_bufdata_cachep);
 
@@ -90,6 +96,7 @@ static int __init init_gfs2_fs(void)
 static void __exit exit_gfs2_fs(void)
 {
 	unregister_filesystem(&gfs2_fs_type);
+	unregister_filesystem(&gfs2meta_fs_type);
 
 	kmem_cache_destroy(gfs2_bufdata_cachep);
 	kmem_cache_destroy(gfs2_inode_cachep);
diff --git a/fs/gfs2/ops_fstype.c b/fs/gfs2/ops_fstype.c
index c3b830b..8d6d941 100644
--- a/fs/gfs2/ops_fstype.c
+++ b/fs/gfs2/ops_fstype.c
@@ -113,9 +113,9 @@ static struct gfs2_sbd *init_sbd(struct super_block *sb)
 	return sdp;
 }
 
-static void init_vfs(struct gfs2_sbd *sdp)
+static void init_vfs(struct super_block *sb, unsigned noatime)
 {
-	struct super_block *sb = sdp->sd_vfs;
+	struct gfs2_sbd *sdp = sb->s_fs_info;
 
 	sb->s_magic = GFS2_MAGIC;
 	sb->s_op = &gfs2_super_ops;
@@ -123,18 +123,10 @@ static void init_vfs(struct gfs2_sbd *sdp)
 	sb->s_maxbytes = MAX_LFS_FILESIZE;
 
 	if (sb->s_flags & (MS_NOATIME | MS_NODIRATIME))
-		set_bit(SDF_NOATIME, &sdp->sd_flags);
+		set_bit(noatime, &sdp->sd_flags);
 
 	/* Don't let the VFS update atimes.  GFS2 handles this itself. */
 	sb->s_flags |= MS_NOATIME | MS_NODIRATIME;
-
-	/* Set up the buffer cache and fill in some fake block size values
-	   to allow us to read-in the on-disk superblock. */
-	sdp->sd_sb.sb_bsize = sb_min_blocksize(sb, GFS2_BASIC_BLOCK);
-	sdp->sd_sb.sb_bsize_shift = sb->s_blocksize_bits;
-	sdp->sd_fsb2bb_shift = sdp->sd_sb.sb_bsize_shift -
-			       GFS2_BASIC_BLOCK_SHIFT;
-	sdp->sd_fsb2bb = 1 << sdp->sd_fsb2bb_shift;
 }
 
 static int init_names(struct gfs2_sbd *sdp, int silent)
@@ -291,18 +283,16 @@ static struct inode *gfs2_lookup_root(struct gfs2_sbd *sdp,
 	error = gfs2_glock_get(sdp, inum->no_addr,
                                &gfs2_inode_glops, CREATE, &gl);
         if (!error) {
-               	error = gfs2_inode_get(gl, inum,
-				       CREATE, &ip);
+               	error = gfs2_inode_get(gl, inum, CREATE, &ip);
 		if (!error) {
-			if (!error) 
-				gfs2_inode_min_init(ip, DT_DIR);
+			gfs2_inode_min_init(ip, DT_DIR);
 			inode = gfs2_ip2v(ip);
 			gfs2_inode_put(ip);
+			gfs2_glock_put(gl);
 			return inode;
 		}
                 gfs2_glock_put(gl);
         }
-
         return ERR_PTR(error);
 }
 
@@ -310,6 +300,7 @@ static int init_sb(struct gfs2_sbd *sdp, int silent, int undo)
 {
 	struct super_block *sb = sdp->sd_vfs;
 	struct gfs2_holder sb_gh;
+	struct gfs2_inum *inum;
 	struct inode *inode;
 	int error = 0;
 
@@ -332,14 +323,15 @@ static int init_sb(struct gfs2_sbd *sdp, int silent, int undo)
 	}
 
 	/* Set up the buffer cache and SB for real */
-	error = -EINVAL;
 	if (sdp->sd_sb.sb_bsize < bdev_hardsect_size(sb->s_bdev)) {
+		error = -EINVAL;
 		fs_err(sdp, "FS block size (%u) is too small for device "
 		       "block size (%u)\n",
 		       sdp->sd_sb.sb_bsize, bdev_hardsect_size(sb->s_bdev));
 		goto out;
 	}
 	if (sdp->sd_sb.sb_bsize > PAGE_SIZE) {
+		error = -EINVAL;
 		fs_err(sdp, "FS block size (%u) is too big for machine "
 		       "page size (%u)\n",
 		       sdp->sd_sb.sb_bsize, (unsigned int)PAGE_SIZE);
@@ -353,7 +345,10 @@ static int init_sb(struct gfs2_sbd *sdp, int silent, int undo)
 	sb_set_blocksize(sb, sdp->sd_sb.sb_bsize);
 
 	/* Get the root inode */
-	inode = gfs2_lookup_root(sdp, &sdp->sd_sb.sb_root_dir);
+	inum = &sdp->sd_sb.sb_root_dir;
+	if (sb->s_type == &gfs2meta_fs_type)
+		inum = &sdp->sd_sb.sb_master_dir;
+	inode = gfs2_lookup_root(sdp, inum);
 	if (IS_ERR(inode)) {
 		error = PTR_ERR(inode);
 		fs_err(sdp, "can't read in root inode: %d\n", error);
@@ -366,10 +361,8 @@ static int init_sb(struct gfs2_sbd *sdp, int silent, int undo)
 		error = -ENOMEM;
 		iput(inode);
 	}
-
 out:
 	gfs2_glock_dq_uninit(&sb_gh);
-
 	return error;
 }
 
@@ -791,7 +784,15 @@ static int fill_super(struct super_block *sb, void *data, int silent)
 		goto fail;
 	}
 
-	init_vfs(sdp);
+	init_vfs(sb, SDF_NOATIME);
+
+	/* Set up the buffer cache and fill in some fake block size values
+	   to allow us to read-in the on-disk superblock. */
+	sdp->sd_sb.sb_bsize = sb_min_blocksize(sb, GFS2_BASIC_BLOCK);
+	sdp->sd_sb.sb_bsize_shift = sb->s_blocksize_bits;
+	sdp->sd_fsb2bb_shift = sdp->sd_sb.sb_bsize_shift -
+                               GFS2_BASIC_BLOCK_SHIFT;
+	sdp->sd_fsb2bb = 1 << sdp->sd_fsb2bb_shift;
 
 	error = init_names(sdp, silent);
 	if (error)
@@ -881,11 +882,24 @@ static struct super_block *gfs2_get_sb(struct file_system_type *fs_type,
 	return get_sb_bdev(fs_type, flags, dev_name, data, fill_super);
 }
 
+static void gfs2_kill_sb(struct super_block *sb)
+{
+	kill_block_super(sb);
+}
+
 struct file_system_type gfs2_fs_type = {
 	.name = "gfs2",
 	.fs_flags = FS_REQUIRES_DEV,
 	.get_sb = gfs2_get_sb,
-	.kill_sb = kill_block_super,
+	.kill_sb = gfs2_kill_sb,
+	.owner = THIS_MODULE,
+};
+
+struct file_system_type gfs2meta_fs_type = {
+	.name = "gfs2meta",
+	.fs_flags = FS_REQUIRES_DEV,
+	.get_sb = gfs2_get_sb,
+	.kill_sb = gfs2_kill_sb,
 	.owner = THIS_MODULE,
 };
 
diff --git a/fs/gfs2/ops_fstype.h b/fs/gfs2/ops_fstype.h
index 7008364..c645287 100644
--- a/fs/gfs2/ops_fstype.h
+++ b/fs/gfs2/ops_fstype.h
@@ -11,5 +11,6 @@
 #define __OPS_FSTYPE_DOT_H__
 
 extern struct file_system_type gfs2_fs_type;
+extern struct file_system_type gfs2meta_fs_type;
 
 #endif /* __OPS_FSTYPE_DOT_H__ */