[GFS2] Allow mounting of gfs2 and gfs2meta at the same time

This patch allows the simultaneous mounting of gfs2meta and gfs2
filesystems. A restriction however is that a gfs2meta fs may only be
mounted if its corresponding gfs2 filesystem is also mounted. Also, a
gfs2 filesystem cannot be unmounted before its gfs2meta filesystem.

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

4 files changed, 155 insertions, 3 deletions

diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
index 005788fb361f..ef713dbff601 100644
--- a/fs/gfs2/glock.c
+++ b/fs/gfs2/glock.c
@@ -1165,7 +1165,13 @@ static void add_to_queue(struct gfs2_holder *gh)
         existing = find_holder_by_owner(&gl->gl_holders, gh->gh_owner);
         if (existing) {
                 print_symbol(KERN_WARNING "original: %s\n", existing->gh_ip);
+                printk(KERN_INFO "pid : %d\n", existing->gh_owner->pid);
+                printk(KERN_INFO "lock type : %d lock state : %d\n", 
+                                existing->gh_gl->gl_name.ln_type, existing->gh_gl->gl_state);
                 print_symbol(KERN_WARNING "new: %s\n", gh->gh_ip);
+                printk(KERN_INFO "pid : %d\n", gh->gh_owner->pid);
+                printk(KERN_INFO "lock type : %d lock state : %d\n", 
+                                gl->gl_name.ln_type, gl->gl_state);
                 BUG();
         }
 
diff --git a/fs/gfs2/incore.h b/fs/gfs2/incore.h
index 78d3cb511eb8..77f0903d2f3e 100644
--- a/fs/gfs2/incore.h
+++ b/fs/gfs2/incore.h
@@ -472,6 +472,7 @@ enum {
 
 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 sd_sb;
@@ -652,6 +653,7 @@ struct gfs2_sbd {
         /* Debugging crud */
 
         unsigned long sd_last_warning;
+        struct vfsmount *sd_gfs2mnt;
 };
 
 #endif /* __INCORE_DOT_H__ */
diff --git a/fs/gfs2/ops_fstype.c b/fs/gfs2/ops_fstype.c
index c66067c84bcf..e5a91ead250c 100644
--- a/fs/gfs2/ops_fstype.c
+++ b/fs/gfs2/ops_fstype.c
@@ -15,6 +15,8 @@
 #include <linux/vmalloc.h>
 #include <linux/blkdev.h>
 #include <linux/kthread.h>
+#include <linux/namei.h>
+#include <linux/mount.h>
 #include <linux/gfs2_ondisk.h>
 
 #include "gfs2.h"
@@ -813,7 +815,138 @@ static int fill_super(struct super_block *sb, void *data, int silent)
 static int gfs2_get_sb(struct file_system_type *fs_type, int flags,
                 const char *dev_name, void *data, struct vfsmount *mnt)
 {
-        return get_sb_bdev(fs_type, flags, dev_name, data, fill_super, mnt);
+        struct super_block *sb;
+        struct gfs2_sbd *sdp;
+        int error = get_sb_bdev(fs_type, flags, dev_name, data, fill_super, mnt);
+        if (error)
+                goto out;
+        sb = mnt->mnt_sb;
+        sdp = (struct gfs2_sbd*)sb->s_fs_info;
+        sdp->sd_gfs2mnt = mnt;
+out:
+        return error;
+}
+
+static int fill_super_meta(struct super_block *sb, struct super_block *new, 
+                           void *data, int silent)
+{
+        struct gfs2_sbd *sdp = sb->s_fs_info;
+        struct inode *inode;
+        int error = 0;
+
+        new->s_fs_info = sdp;
+        sdp->sd_vfs_meta = sb;
+
+        init_vfs(new, SDF_NOATIME);
+
+        /* Get the master inode */
+        inode = igrab(sdp->sd_master_dir);
+
+        new->s_root = d_alloc_root(inode);
+        if (!new->s_root) {
+                fs_err(sdp, "can't get root dentry\n");
+                error = -ENOMEM;
+                iput(inode);
+        }
+        new->s_root->d_op = &gfs2_dops;
+
+        return error;
+}
+static int set_bdev_super(struct super_block *s, void *data)
+{
+        s->s_bdev = data;
+        s->s_dev = s->s_bdev->bd_dev;
+        return 0;
+}
+ 
+static int test_bdev_super(struct super_block *s, void *data)
+{
+        return (void *)s->s_bdev == data;
+}
+
+static struct super_block* get_gfs2_sb(const char *dev_name)
+{
+        struct kstat stat;
+        struct nameidata nd;
+        struct file_system_type *fstype;
+        struct super_block *sb = NULL, *s;
+        struct list_head *l;
+        int error;
+        
+        error = path_lookup(dev_name, LOOKUP_FOLLOW, &nd);
+        if (error) {
+                printk(KERN_WARNING "GFS2: path_lookup on %s returned error\n", 
+                       dev_name);
+                goto out;
+        }
+        error = vfs_getattr(nd.mnt, nd.dentry, &stat);
+
+        fstype = get_fs_type("gfs2");
+        list_for_each(l, &fstype->fs_supers) {
+                s = list_entry(l, struct super_block, s_instances);
+                if ((S_ISBLK(stat.mode) && s->s_dev == stat.rdev) ||
+                    (S_ISDIR(stat.mode) && s == nd.dentry->d_inode->i_sb)) {
+                        sb = s;
+                        goto free_nd;
+                }
+        }
+
+        printk(KERN_WARNING "GFS2: Unrecognized block device or "
+               "mount point %s", dev_name);
+
+free_nd:
+        path_release(&nd);
+out:
+        return sb;
+}
+
+static int gfs2_get_sb_meta(struct file_system_type *fs_type, int flags,
+                            const char *dev_name, void *data, struct vfsmount *mnt)
+{
+        int error = 0;
+        struct super_block *sb = NULL, *new;
+        struct gfs2_sbd *sdp;
+        char *gfs2mnt = NULL;
+
+        sb = get_gfs2_sb(dev_name);
+        if (!sb) {
+                printk(KERN_WARNING "GFS2: gfs2 mount does not exist\n");
+                error = -ENOENT;
+                goto error;
+        }
+        sdp = (struct gfs2_sbd*) sb->s_fs_info;
+        if (sdp->sd_vfs_meta) {
+                printk(KERN_WARNING "GFS2: gfs2meta mount already exists\n");
+                error = -EBUSY;
+                goto error;
+        }
+        mutex_lock(&sb->s_bdev->bd_mount_mutex);
+        new = sget(fs_type, test_bdev_super, set_bdev_super, sb->s_bdev);
+        mutex_unlock(&sb->s_bdev->bd_mount_mutex);
+        if (IS_ERR(new)) {
+                error = PTR_ERR(new);
+                goto error;
+        }
+        module_put(fs_type->owner);
+        new->s_flags = flags;
+        strlcpy(new->s_id, sb->s_id, sizeof(new->s_id));
+        sb_set_blocksize(new, sb->s_blocksize);
+        error = fill_super_meta(sb, new, data, flags & MS_SILENT ? 1 : 0);
+        if (error) {
+                up_write(&new->s_umount);
+                deactivate_super(new);
+                goto error;
+        }
+        
+        new->s_flags |= MS_ACTIVE;
+        
+        /* Grab a reference to the gfs2 mount point */
+        atomic_inc(&sdp->sd_gfs2mnt->mnt_count);
+        return simple_set_mnt(mnt, new);
+error:
+        if (gfs2mnt)
+                kfree(gfs2mnt);
+        return error;
 }
 
 static void gfs2_kill_sb(struct super_block *sb)
@@ -821,6 +954,14 @@ static void gfs2_kill_sb(struct super_block *sb)
         kill_block_super(sb);
 }
 
+static void gfs2_kill_sb_meta(struct super_block *sb)
+{
+        struct gfs2_sbd *sdp = sb->s_fs_info;
+        generic_shutdown_super(sb);
+        sdp->sd_vfs_meta = NULL;
+        atomic_dec(&sdp->sd_gfs2mnt->mnt_count);
+}
+
 struct file_system_type gfs2_fs_type = {
         .name = "gfs2",
         .fs_flags = FS_REQUIRES_DEV,
@@ -832,8 +973,8 @@ struct file_system_type gfs2_fs_type = {
 struct file_system_type gfs2meta_fs_type = {
         .name = "gfs2meta",
         .fs_flags = FS_REQUIRES_DEV,
-        .get_sb = gfs2_get_sb,
-        .kill_sb = gfs2_kill_sb,
+        .get_sb = gfs2_get_sb_meta,
+        .kill_sb = gfs2_kill_sb_meta,
         .owner = THIS_MODULE,
 };
 
diff --git a/fs/gfs2/ops_super.c b/fs/gfs2/ops_super.c
index 2e392c994ab1..18ed18c729e8 100644
--- a/fs/gfs2/ops_super.c
+++ b/fs/gfs2/ops_super.c
@@ -78,6 +78,9 @@ static void gfs2_put_super(struct super_block *sb)
         if (!sdp)
                 return;
 
+        if (!strncmp(sb->s_type->name, "gfs2meta", 8))
+                return; /* meta fs. don't do nothin' */
+
         /*  Unfreeze the filesystem, if we need to  */
 
         mutex_lock(&sdp->sd_freeze_lock);