staging/lustre/llite: return valid fsid for statfs

Lustre uses 64-bits inode number to identify object on client side.
When re-export Lustre via NFS, NFS will detect whether support fsid
via statfs(). For the non-support case, it will only recognizes and
packs low 32-bits inode number in nfs handle. Such handle cannot be
used to locate the object properly.

To avoid patch linux kernel, Lustre client should generate fsid and
return it via statfs() to up layer.

Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-2904
Lustre-change: http://review.whamcloud.com/6493Signed-off-by: NFan Yong <fan.yong@intel.com>
Reviewed-by: NAndreas Dilger <andreas.dilger@intel.com>
Reviewed-by: NLai Siyao <lai.siyao@intel.com>
Reviewed-by: NOleg Drokin <oleg.drokin@intel.com>
Signed-off-by: NPeng Tao <tao.peng@emc.com>
Signed-off-by: NAndreas Dilger <andreas.dilger@intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/lustre/lustre/llite/llite_internal.h

@@ -505,6 +505,7 @@ struct ll_sb_info {
 						 * clustred nfs */
 	struct rmtacl_ctl_table   ll_rct;
 	struct eacl_table	 ll_et;
+	__kernel_fsid_t		  ll_fsid;
 };
 
 #define LL_DEFAULT_MAX_RW_CHUNK      (32 * 1024 * 1024)
@@ -833,6 +834,7 @@ char *ll_get_fsname(struct super_block *sb, char *buf, int buflen);
 /* llite/llite_nfs.c */
 extern struct export_operations lustre_export_operations;
 __u32 get_uuid2int(const char *name, int len);
+void get_uuid2fsid(const char *name, int len, __kernel_fsid_t *fsid);
 struct inode *search_inode_for_lustre(struct super_block *sb,
 				      const struct lu_fid *fid);
 

drivers/staging/lustre/lustre/llite/llite_lib.c

@@ -583,8 +583,10 @@ static int client_common_fill_super(struct super_block *sb, char *md, char *dt,
 	/* s_dev is also used in lt_compare() to compare two fs, but that is
 	 * only a node-local comparison. */
 	uuid = obd_get_uuid(sbi->ll_md_exp);
-	if (uuid != NULL)
+	if (uuid != NULL) {
 		sb->s_dev = get_uuid2int(uuid->uuid, strlen(uuid->uuid));
+		get_uuid2fsid(uuid->uuid, strlen(uuid->uuid), &sbi->ll_fsid);
+	}
 
 	if (data != NULL)
 		OBD_FREE_PTR(data);
@@ -1615,7 +1617,7 @@ int ll_statfs(struct dentry *de, struct kstatfs *sfs)
 	sfs->f_blocks = osfs.os_blocks;
 	sfs->f_bfree = osfs.os_bfree;
 	sfs->f_bavail = osfs.os_bavail;
-
+	sfs->f_fsid = ll_s2sbi(sb)->ll_fsid;
 	return 0;
 }
 

drivers/staging/lustre/lustre/llite/llite_nfs.c

@@ -58,6 +58,22 @@ __u32 get_uuid2int(const char *name, int len)
 	return (key0 << 1);
 }
 
+void get_uuid2fsid(const char *name, int len, __kernel_fsid_t *fsid)
+{
+	__u64 key = 0, key0 = 0x12a3fe2d, key1 = 0x37abe8f9;
+
+	while (len--) {
+		key = key1 + (key0 ^ (*name++ * 7152373));
+		if (key & 0x8000000000000000ULL)
+			key -= 0x7fffffffffffffffULL;
+		key1 = key0;
+		key0 = key;
+	}
+
+	fsid->val[0] = key;
+	fsid->val[1] = key >> 32;
+}
+
 static int ll_nfs_test_inode(struct inode *inode, void *opaque)
 {
 	return lu_fid_eq(&ll_i2info(inode)->lli_fid,