Make ZFS filesystem id persistent across different machines

Use ZFS dataset fsid guid as a unique file system id, similar to what is
done on Illumos/OpenSolaris.

Signed-off-by: Cyril Plisko <cyril.plisko@mountall.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #888

diff --git a/module/zfs/zfs_vfsops.c b/module/zfs/zfs_vfsops.c
index 1efe6a8..8fe457e 100644 (file)
--- a/module/zfs/zfs_vfsops.c
+++ b/module/zfs/zfs_vfsops.c
@@ -920,6 +920,7 @@ zfs_statvfs(struct dentry *dentry, struct kstatfs *statp)
 {
        zfs_sb_t *zsb = dentry->d_sb->s_fs_info;
        uint64_t refdbytes, availbytes, usedobjs, availobjs;
+       uint64_t fsid;
        uint32_t bshift;
 
        ZFS_ENTER(zsb);
@@ -927,6 +928,7 @@ zfs_statvfs(struct dentry *dentry, struct kstatfs *statp)
        dmu_objset_space(zsb->z_os,
            &refdbytes, &availbytes, &usedobjs, &availobjs);
 
+       fsid = dmu_objset_fsid_guid(zsb->z_os);
        /*
         * The underlying storage pool actually uses multiple block
         * size.  Under Solaris frsize (fragment size) is reported as
@@ -960,8 +962,8 @@ zfs_statvfs(struct dentry *dentry, struct kstatfs *statp)
         */
        statp->f_ffree = MIN(availobjs, availbytes >> DNODE_SHIFT);
        statp->f_files = statp->f_ffree + usedobjs;
-       statp->f_fsid.val[0] = dentry->d_sb->s_dev;
-       statp->f_fsid.val[1] = 0;
+       statp->f_fsid.val[0] = (uint32_t)fsid;
+       statp->f_fsid.val[1] = (uint32_t)(fsid >> 32);
        statp->f_type = ZFS_SUPER_MAGIC;
        statp->f_namelen = ZFS_MAXNAMELEN;