GFS2: Fix locking issue mounting gfs2meta fs
This patch uses sget() to get a reference to the
existing gfs2 sb when mouting the gfs2meta filesystem
(in fact thats just another mount of the gfs2
filesystem with a different root and this interface
is for backward compatibility).
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
Reported-by: Benjamin Marzinski <bmarzins@redhat.com>
Tested-by: Benjamin Marzinski <bmarzins@redhat.com>
Cc: Christoph Hellwig <hch@infradead.org>
diff --git a/fs/gfs2/ops_fstype.c b/fs/gfs2/ops_fstype.c
index 2cd1164..9da161c 100644
--- a/fs/gfs2/ops_fstype.c
+++ b/fs/gfs2/ops_fstype.c
@@ -1273,9 +1273,20 @@
return get_sb_bdev(fs_type, flags, dev_name, data, fill_super, mnt);
}
+static int test_meta_super(struct super_block *s, void *ptr)
+{
+ struct block_device *bdev = ptr;
+ return (bdev == s->s_bdev);
+}
+
+static int set_meta_super(struct super_block *s, void *ptr)
+{
+ return -EINVAL;
+}
+
static struct super_block *get_gfs2_sb(const char *dev_name)
{
- struct super_block *sb;
+ struct super_block *s;
struct path path;
int error;
@@ -1283,30 +1294,27 @@
if (error) {
printk(KERN_WARNING "GFS2: path_lookup on %s returned error %d\n",
dev_name, error);
- return NULL;
+ return ERR_PTR(-ENOENT);
}
- sb = path.dentry->d_inode->i_sb;
- if (sb && (sb->s_type == &gfs2_fs_type))
- atomic_inc(&sb->s_active);
- else
- sb = NULL;
+ s = sget(&gfs2_fs_type, test_meta_super, set_meta_super,
+ path.dentry->d_inode->i_sb->s_bdev);
path_put(&path);
- return sb;
+ return s;
}
static int gfs2_get_sb_meta(struct file_system_type *fs_type, int flags,
const char *dev_name, void *data, struct vfsmount *mnt)
{
- struct super_block *sb = NULL;
+ struct super_block *s;
struct gfs2_sbd *sdp;
- sb = get_gfs2_sb(dev_name);
- if (!sb) {
+ s = get_gfs2_sb(dev_name);
+ if (IS_ERR(s)) {
printk(KERN_WARNING "GFS2: gfs2 mount does not exist\n");
- return -ENOENT;
+ return PTR_ERR(s);
}
- sdp = sb->s_fs_info;
- mnt->mnt_sb = sb;
+ sdp = s->s_fs_info;
+ mnt->mnt_sb = s;
mnt->mnt_root = dget(sdp->sd_master_dir);
return 0;
}