GFS2: Fix metafs mounts

This patch is intended to fix the issues reported in bz #457798. Instead
of having the metafs as a separate filesystem, it becomes a second root
of gfs2. As a result it will appear as type gfs2 in /proc/mounts, but it
is still possible (for backwards compatibility purposes) to mount it as
type gfs2meta. A new mount flag "meta" is introduced so that its possible
to tell the two cases apart in /proc/mounts.

As a result it becomes possible to mount type gfs2 with -o meta and
get the same result as mounting type gfs2meta. So it is possible to
mount just the metafs on its own. Currently if you do this, its then
impossible to mount the "normal" root of the gfs2 filesystem without
first unmounting the metafs root. I'm not sure if thats a feature or
a bug :-)

Either way, this is a great improvement on the previous scheme and I've
verified that it works ok with bind mounts on both the "normal" root
and the metafs root in various combinations.

There were also a bunch of functions in super.c which didn't belong there,
so this moves them into ops_fstype.c where they can be static. Hopefully
the mount/umount sequence is now more obvious as a result.
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
Cc: Alexander Viro <aviro@redhat.com>

fs/gfs2/incore.h

@@ -400,6 +400,7 @@ struct gfs2_args {
 	int ar_quota; /* off/account/on */
 	int ar_suiddir; /* suiddir support */
 	int ar_data; /* ordered/writeback */
+	int ar_meta; /* mount metafs */
 };
 
 struct gfs2_tune {
@@ -461,7 +462,6 @@ struct gfs2_sb_host {
 
 struct gfs2_sbd {
 	struct super_block *sd_vfs;
-	struct super_block *sd_vfs_meta;
 	struct kobject sd_kobj;
 	unsigned long sd_flags;	/* SDF_... */
 	struct gfs2_sb_host sd_sb;
@@ -499,7 +499,9 @@ struct gfs2_sbd {
 
 	/* Inode Stuff */
 
-	struct inode *sd_master_dir;
+	struct dentry *sd_master_dir;
+	struct dentry *sd_root_dir;
+
 	struct inode *sd_jindex;
 	struct inode *sd_inum_inode;
 	struct inode *sd_statfs_inode;
@@ -634,7 +636,6 @@ struct gfs2_sbd {
 	/* Debugging crud */
 
 	unsigned long sd_last_warning;
-	struct vfsmount *sd_gfs2mnt;
 	struct dentry *debugfs_dir;    /* debugfs directory */
 	struct dentry *debugfs_dentry_glocks; /* for debugfs */
 };

fs/gfs2/mount.c

@@ -42,6 +42,7 @@ enum {
 	Opt_nosuiddir,
 	Opt_data_writeback,
 	Opt_data_ordered,
+	Opt_meta,
 	Opt_err,
 };
 
@@ -66,6 +67,7 @@ static match_table_t tokens = {
 	{Opt_nosuiddir, "nosuiddir"},
 	{Opt_data_writeback, "data=writeback"},
 	{Opt_data_ordered, "data=ordered"},
+	{Opt_meta, "meta"},
 	{Opt_err, NULL}
 };
 
@@ -239,6 +241,11 @@ int gfs2_mount_args(struct gfs2_sbd *sdp, char *data_arg, int remount)
 		case Opt_data_ordered:
 			args->ar_data = GFS2_DATA_ORDERED;
 			break;
+		case Opt_meta:
+			if (remount && args->ar_meta != 1)
+				goto cant_remount;
+			args->ar_meta = 1;
+			break;
 		case Opt_err:
 		default:
 			fs_info(sdp, "unknown option: %s\n", o);

fs/gfs2/ops_super.c

@@ -62,6 +62,39 @@ static int gfs2_write_inode(struct inode *inode, int sync)
 	return 0;
 }
 
+/**
+ * gfs2_make_fs_ro - Turn a Read-Write FS into a Read-Only one
+ * @sdp: the filesystem
+ *
+ * Returns: errno
+ */
+
+static int gfs2_make_fs_ro(struct gfs2_sbd *sdp)
+{
+	struct gfs2_holder t_gh;
+	int error;
+
+	gfs2_quota_sync(sdp);
+	gfs2_statfs_sync(sdp);
+
+	error = gfs2_glock_nq_init(sdp->sd_trans_gl, LM_ST_SHARED, GL_NOCACHE,
+				   &t_gh);
+	if (error && !test_bit(SDF_SHUTDOWN, &sdp->sd_flags))
+		return error;
+
+	gfs2_meta_syncfs(sdp);
+	gfs2_log_shutdown(sdp);
+
+	clear_bit(SDF_JOURNAL_LIVE, &sdp->sd_flags);
+
+	if (t_gh.gh_gl)
+		gfs2_glock_dq_uninit(&t_gh);
+
+	gfs2_quota_cleanup(sdp);
+
+	return error;
+}
+
 /**
  * gfs2_put_super - Unmount the filesystem
  * @sb: The VFS superblock
@@ -73,12 +106,6 @@ static void gfs2_put_super(struct super_block *sb)
 	struct gfs2_sbd *sdp = sb->s_fs_info;
 	int error;
 
-	if (!sdp)
-		return;
-
-	if (!strncmp(sb->s_type->name, "gfs2meta", 8))
-		return; /* Nothing to do */
-
 	/*  Unfreeze the filesystem, if we need to  */
 
 	mutex_lock(&sdp->sd_freeze_lock);
@@ -101,7 +128,6 @@ static void gfs2_put_super(struct super_block *sb)
 
 	/*  Release stuff  */
 
-	iput(sdp->sd_master_dir);
 	iput(sdp->sd_jindex);
 	iput(sdp->sd_inum_inode);
 	iput(sdp->sd_statfs_inode);
@@ -152,6 +178,7 @@ static void gfs2_write_super(struct super_block *sb)
  *
  * Flushes the log to disk.
  */
+
 static int gfs2_sync_fs(struct super_block *sb, int wait)
 {
 	sb->s_dirt = 0;
@@ -295,6 +322,7 @@ static int gfs2_remount_fs(struct super_block *sb, int *flags, char *data)
  * inode's blocks, or alternatively pass the baton on to another
  * node for later deallocation.
  */
+
 static void gfs2_drop_inode(struct inode *inode)
 {
 	struct gfs2_inode *ip = GFS2_I(inode);
@@ -333,6 +361,16 @@ static void gfs2_clear_inode(struct inode *inode)
 	}
 }
 
+static int is_ancestor(const struct dentry *d1, const struct dentry *d2)
+{
+	do {
+		if (d1 == d2)
+			return 1;
+		d1 = d1->d_parent;
+	} while (!IS_ROOT(d1));
+	return 0;
+}
+
 /**
  * gfs2_show_options - Show mount options for /proc/mounts
  * @s: seq_file structure
@@ -346,6 +384,8 @@ static int gfs2_show_options(struct seq_file *s, struct vfsmount *mnt)
 	struct gfs2_sbd *sdp = mnt->mnt_sb->s_fs_info;
 	struct gfs2_args *args = &sdp->sd_args;
 
+	if (is_ancestor(mnt->mnt_root, sdp->sd_master_dir))
+		seq_printf(s, ",meta");
 	if (args->ar_lockproto[0])
 		seq_printf(s, ",lockproto=%s", args->ar_lockproto);
 	if (args->ar_locktable[0])
@@ -414,6 +454,7 @@ static int gfs2_show_options(struct seq_file *s, struct vfsmount *mnt)
  * conversion on the iopen lock, but we can change that later. This
  * is safe, just less efficient.
  */
+
 static void gfs2_delete_inode(struct inode *inode)
 {
 	struct gfs2_sbd *sdp = inode->i_sb->s_fs_info;
@@ -478,8 +519,6 @@ static void gfs2_delete_inode(struct inode *inode)
 	clear_inode(inode);
 }
 
-
-
 static struct inode *gfs2_alloc_inode(struct super_block *sb)
 {
 	struct gfs2_inode *ip;

fs/gfs2/super.c

@@ -33,313 +33,6 @@
 #include "trans.h"
 #include "util.h"
 
-static const u32 gfs2_old_fs_formats[] = {
-        0
-};
-
-static const u32 gfs2_old_multihost_formats[] = {
-        0
-};
-
-/**
- * gfs2_tune_init - Fill a gfs2_tune structure with default values
- * @gt: tune
- *
- */
-
-void gfs2_tune_init(struct gfs2_tune *gt)
-{
-	spin_lock_init(&gt->gt_spin);
-
-	gt->gt_demote_secs = 300;
-	gt->gt_incore_log_blocks = 1024;
-	gt->gt_log_flush_secs = 60;
-	gt->gt_recoverd_secs = 60;
-	gt->gt_logd_secs = 1;
-	gt->gt_quotad_secs = 5;
-	gt->gt_quota_simul_sync = 64;
-	gt->gt_quota_warn_period = 10;
-	gt->gt_quota_scale_num = 1;
-	gt->gt_quota_scale_den = 1;
-	gt->gt_quota_cache_secs = 300;
-	gt->gt_quota_quantum = 60;
-	gt->gt_atime_quantum = 3600;
-	gt->gt_new_files_jdata = 0;
-	gt->gt_max_readahead = 1 << 18;
-	gt->gt_stall_secs = 600;
-	gt->gt_complain_secs = 10;
-	gt->gt_statfs_quantum = 30;
-	gt->gt_statfs_slow = 0;
-}
-
-/**
- * gfs2_check_sb - Check superblock
- * @sdp: the filesystem
- * @sb: The superblock
- * @silent: Don't print a message if the check fails
- *
- * Checks the version code of the FS is one that we understand how to
- * read and that the sizes of the various on-disk structures have not
- * changed.
- */
-
-int gfs2_check_sb(struct gfs2_sbd *sdp, struct gfs2_sb_host *sb, int silent)
-{
-	unsigned int x;
-
-	if (sb->sb_magic != GFS2_MAGIC ||
-	    sb->sb_type != GFS2_METATYPE_SB) {
-		if (!silent)
-			printk(KERN_WARNING "GFS2: not a GFS2 filesystem\n");
-		return -EINVAL;
-	}
-
-	/*  If format numbers match exactly, we're done.  */
-
-	if (sb->sb_fs_format == GFS2_FORMAT_FS &&
-	    sb->sb_multihost_format == GFS2_FORMAT_MULTI)
-		return 0;
-
-	if (sb->sb_fs_format != GFS2_FORMAT_FS) {
-		for (x = 0; gfs2_old_fs_formats[x]; x++)
-			if (gfs2_old_fs_formats[x] == sb->sb_fs_format)
-				break;
-
-		if (!gfs2_old_fs_formats[x]) {
-			printk(KERN_WARNING
-			       "GFS2: code version (%u, %u) is incompatible "
-			       "with ondisk format (%u, %u)\n",
-			       GFS2_FORMAT_FS, GFS2_FORMAT_MULTI,
-			       sb->sb_fs_format, sb->sb_multihost_format);
-			printk(KERN_WARNING
-			       "GFS2: I don't know how to upgrade this FS\n");
-			return -EINVAL;
-		}
-	}
-
-	if (sb->sb_multihost_format != GFS2_FORMAT_MULTI) {
-		for (x = 0; gfs2_old_multihost_formats[x]; x++)
-			if (gfs2_old_multihost_formats[x] ==
-			    sb->sb_multihost_format)
-				break;
-
-		if (!gfs2_old_multihost_formats[x]) {
-			printk(KERN_WARNING
-			       "GFS2: code version (%u, %u) is incompatible "
-			       "with ondisk format (%u, %u)\n",
-			       GFS2_FORMAT_FS, GFS2_FORMAT_MULTI,
-			       sb->sb_fs_format, sb->sb_multihost_format);
-			printk(KERN_WARNING
-			       "GFS2: I don't know how to upgrade this FS\n");
-			return -EINVAL;
-		}
-	}
-
-	if (!sdp->sd_args.ar_upgrade) {
-		printk(KERN_WARNING
-		       "GFS2: code version (%u, %u) is incompatible "
-		       "with ondisk format (%u, %u)\n",
-		       GFS2_FORMAT_FS, GFS2_FORMAT_MULTI,
-		       sb->sb_fs_format, sb->sb_multihost_format);
-		printk(KERN_INFO
-		       "GFS2: Use the \"upgrade\" mount option to upgrade "
-		       "the FS\n");
-		printk(KERN_INFO "GFS2: See the manual for more details\n");
-		return -EINVAL;
-	}
-
-	return 0;
-}
-
-
-static void end_bio_io_page(struct bio *bio, int error)
-{
-	struct page *page = bio->bi_private;
-
-	if (!error)
-		SetPageUptodate(page);
-	else
-		printk(KERN_WARNING "gfs2: error %d reading superblock\n", error);
-	unlock_page(page);
-}
-
-static void gfs2_sb_in(struct gfs2_sb_host *sb, const void *buf)
-{
-	const struct gfs2_sb *str = buf;
-
-	sb->sb_magic = be32_to_cpu(str->sb_header.mh_magic);
-	sb->sb_type = be32_to_cpu(str->sb_header.mh_type);
-	sb->sb_format = be32_to_cpu(str->sb_header.mh_format);
-	sb->sb_fs_format = be32_to_cpu(str->sb_fs_format);
-	sb->sb_multihost_format = be32_to_cpu(str->sb_multihost_format);
-	sb->sb_bsize = be32_to_cpu(str->sb_bsize);
-	sb->sb_bsize_shift = be32_to_cpu(str->sb_bsize_shift);
-	sb->sb_master_dir.no_addr = be64_to_cpu(str->sb_master_dir.no_addr);
-	sb->sb_master_dir.no_formal_ino = be64_to_cpu(str->sb_master_dir.no_formal_ino);
-	sb->sb_root_dir.no_addr = be64_to_cpu(str->sb_root_dir.no_addr);
-	sb->sb_root_dir.no_formal_ino = be64_to_cpu(str->sb_root_dir.no_formal_ino);
-
-	memcpy(sb->sb_lockproto, str->sb_lockproto, GFS2_LOCKNAME_LEN);
-	memcpy(sb->sb_locktable, str->sb_locktable, GFS2_LOCKNAME_LEN);
-}
-
-/**
- * gfs2_read_super - Read the gfs2 super block from disk
- * @sdp: The GFS2 super block
- * @sector: The location of the super block
- * @error: The error code to return
- *
- * This uses the bio functions to read the super block from disk
- * because we want to be 100% sure that we never read cached data.
- * A super block is read twice only during each GFS2 mount and is
- * never written to by the filesystem. The first time its read no
- * locks are held, and the only details which are looked at are those
- * relating to the locking protocol. Once locking is up and working,
- * the sb is read again under the lock to establish the location of
- * the master directory (contains pointers to journals etc) and the
- * root directory.
- *
- * Returns: 0 on success or error
- */
-
-int gfs2_read_super(struct gfs2_sbd *sdp, sector_t sector)
-{
-	struct super_block *sb = sdp->sd_vfs;
-	struct gfs2_sb *p;
-	struct page *page;
-	struct bio *bio;
-
-	page = alloc_page(GFP_NOFS);
-	if (unlikely(!page))
-		return -ENOBUFS;
-
-	ClearPageUptodate(page);
-	ClearPageDirty(page);
-	lock_page(page);
-
-	bio = bio_alloc(GFP_NOFS, 1);
-	if (unlikely(!bio)) {
-		__free_page(page);
-		return -ENOBUFS;
-	}
-
-	bio->bi_sector = sector * (sb->s_blocksize >> 9);
-	bio->bi_bdev = sb->s_bdev;
-	bio_add_page(bio, page, PAGE_SIZE, 0);
-
-	bio->bi_end_io = end_bio_io_page;
-	bio->bi_private = page;
-	submit_bio(READ_SYNC | (1 << BIO_RW_META), bio);
-	wait_on_page_locked(page);
-	bio_put(bio);
-	if (!PageUptodate(page)) {
-		__free_page(page);
-		return -EIO;
-	}
-	p = kmap(page);
-	gfs2_sb_in(&sdp->sd_sb, p);
-	kunmap(page);
-	__free_page(page);
-	return 0;
-}
-
-/**
- * gfs2_read_sb - Read super block
- * @sdp: The GFS2 superblock
- * @gl: the glock for the superblock (assumed to be held)
- * @silent: Don't print message if mount fails
- *
- */
-
-int gfs2_read_sb(struct gfs2_sbd *sdp, struct gfs2_glock *gl, int silent)
-{
-	u32 hash_blocks, ind_blocks, leaf_blocks;
-	u32 tmp_blocks;
-	unsigned int x;
-	int error;
-
-	error = gfs2_read_super(sdp, GFS2_SB_ADDR >> sdp->sd_fsb2bb_shift);
-	if (error) {
-		if (!silent)
-			fs_err(sdp, "can't read superblock\n");
-		return error;
-	}
-
-	error = gfs2_check_sb(sdp, &sdp->sd_sb, silent);
-	if (error)
-		return error;
-
-	sdp->sd_fsb2bb_shift = sdp->sd_sb.sb_bsize_shift -
-			       GFS2_BASIC_BLOCK_SHIFT;
-	sdp->sd_fsb2bb = 1 << sdp->sd_fsb2bb_shift;
-	sdp->sd_diptrs = (sdp->sd_sb.sb_bsize -
-			  sizeof(struct gfs2_dinode)) / sizeof(u64);
-	sdp->sd_inptrs = (sdp->sd_sb.sb_bsize -
-			  sizeof(struct gfs2_meta_header)) / sizeof(u64);
-	sdp->sd_jbsize = sdp->sd_sb.sb_bsize - sizeof(struct gfs2_meta_header);
-	sdp->sd_hash_bsize = sdp->sd_sb.sb_bsize / 2;
-	sdp->sd_hash_bsize_shift = sdp->sd_sb.sb_bsize_shift - 1;
-	sdp->sd_hash_ptrs = sdp->sd_hash_bsize / sizeof(u64);
-	sdp->sd_qc_per_block = (sdp->sd_sb.sb_bsize -
-				sizeof(struct gfs2_meta_header)) /
-			        sizeof(struct gfs2_quota_change);
-
-	/* Compute maximum reservation required to add a entry to a directory */
-
-	hash_blocks = DIV_ROUND_UP(sizeof(u64) * (1 << GFS2_DIR_MAX_DEPTH),
-			     sdp->sd_jbsize);
-
-	ind_blocks = 0;
-	for (tmp_blocks = hash_blocks; tmp_blocks > sdp->sd_diptrs;) {
-		tmp_blocks = DIV_ROUND_UP(tmp_blocks, sdp->sd_inptrs);
-		ind_blocks += tmp_blocks;
-	}
-
-	leaf_blocks = 2 + GFS2_DIR_MAX_DEPTH;
-
-	sdp->sd_max_dirres = hash_blocks + ind_blocks + leaf_blocks;
-
-	sdp->sd_heightsize[0] = sdp->sd_sb.sb_bsize -
-				sizeof(struct gfs2_dinode);
-	sdp->sd_heightsize[1] = sdp->sd_sb.sb_bsize * sdp->sd_diptrs;
-	for (x = 2;; x++) {
-		u64 space, d;
-		u32 m;
-
-		space = sdp->sd_heightsize[x - 1] * sdp->sd_inptrs;
-		d = space;
-		m = do_div(d, sdp->sd_inptrs);
-
-		if (d != sdp->sd_heightsize[x - 1] || m)
-			break;
-		sdp->sd_heightsize[x] = space;
-	}
-	sdp->sd_max_height = x;
-	sdp->sd_heightsize[x] = ~0;
-	gfs2_assert(sdp, sdp->sd_max_height <= GFS2_MAX_META_HEIGHT);
-
-	sdp->sd_jheightsize[0] = sdp->sd_sb.sb_bsize -
-				 sizeof(struct gfs2_dinode);
-	sdp->sd_jheightsize[1] = sdp->sd_jbsize * sdp->sd_diptrs;
-	for (x = 2;; x++) {
-		u64 space, d;
-		u32 m;
-
-		space = sdp->sd_jheightsize[x - 1] * sdp->sd_inptrs;
-		d = space;
-		m = do_div(d, sdp->sd_inptrs);
-
-		if (d != sdp->sd_jheightsize[x - 1] || m)
-			break;
-		sdp->sd_jheightsize[x] = space;
-	}
-	sdp->sd_max_jheight = x;
-	sdp->sd_jheightsize[x] = ~0;
-	gfs2_assert(sdp, sdp->sd_max_jheight <= GFS2_MAX_META_HEIGHT);
-
-	return 0;
-}
-
 /**
  * gfs2_jindex_hold - Grab a lock on the jindex
  * @sdp: The GFS2 superblock
@@ -581,39 +274,6 @@ int gfs2_make_fs_rw(struct gfs2_sbd *sdp)
 	return error;
 }
 
-/**
- * gfs2_make_fs_ro - Turn a Read-Write FS into a Read-Only one
- * @sdp: the filesystem
- *
- * Returns: errno
- */
-
-int gfs2_make_fs_ro(struct gfs2_sbd *sdp)
-{
-	struct gfs2_holder t_gh;
-	int error;
-
-	gfs2_quota_sync(sdp);
-	gfs2_statfs_sync(sdp);
-
-	error = gfs2_glock_nq_init(sdp->sd_trans_gl, LM_ST_SHARED, GL_NOCACHE,
-				   &t_gh);
-	if (error && !test_bit(SDF_SHUTDOWN, &sdp->sd_flags))
-		return error;
-
-	gfs2_meta_syncfs(sdp);
-	gfs2_log_shutdown(sdp);
-
-	clear_bit(SDF_JOURNAL_LIVE, &sdp->sd_flags);
-
-	if (t_gh.gh_gl)
-		gfs2_glock_dq_uninit(&t_gh);
-
-	gfs2_quota_cleanup(sdp);
-
-	return error;
-}
-
 static void gfs2_statfs_change_in(struct gfs2_statfs_change_host *sc, const void *buf)
 {
 	const struct gfs2_statfs_change *str = buf;

fs/gfs2/super.h

@@ -12,11 +12,6 @@
 
 #include "incore.h"
 
-void gfs2_tune_init(struct gfs2_tune *gt);
-
-int gfs2_check_sb(struct gfs2_sbd *sdp, struct gfs2_sb_host *sb, int silent);
-int gfs2_read_sb(struct gfs2_sbd *sdp, struct gfs2_glock *gl, int silent);
-int gfs2_read_super(struct gfs2_sbd *sdp, sector_t sector);
 void gfs2_lm_unmount(struct gfs2_sbd *sdp);
 
 static inline unsigned int gfs2_jindex_size(struct gfs2_sbd *sdp)
@@ -40,7 +35,6 @@ int gfs2_lookup_in_master_dir(struct gfs2_sbd *sdp, char *filename,
 			      struct gfs2_inode **ipp);
 
 int gfs2_make_fs_rw(struct gfs2_sbd *sdp);
-int gfs2_make_fs_ro(struct gfs2_sbd *sdp);
 
 int gfs2_statfs_init(struct gfs2_sbd *sdp);
 void gfs2_statfs_change(struct gfs2_sbd *sdp,