[PATCH] ext2: fsid for statvfs

Update ext2_statfs to return an FSID that is a 64 bit XOR of the 128 bit
filesystem UUID as suggested by Andreas Dilger.  See the following Bugzilla
entry for details:

  http://bugzilla.kernel.org/show_bug.cgi?id=136

Cc: Andreas Dilger <adilger@clusterfs.com>
Cc: Stephen Tweedie <sct@redhat.com>
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 12 insertions, 6 deletions

diff --git a/fs/ext2/super.c b/fs/ext2/super.c
index 3aafb1dd917..255cef5f742 100644
--- a/fs/ext2/super.c
+++ b/fs/ext2/super.c
@@ -1090,8 +1090,10 @@ static int ext2_statfs (struct dentry * dentry, struct kstatfs * buf)
 {
         struct super_block *sb = dentry->d_sb;
         struct ext2_sb_info *sbi = EXT2_SB(sb);
+        struct ext2_super_block *es = sbi->s_es;
         unsigned long overhead;
         int i;
+        u64 fsid;
 
         if (test_opt (sb, MINIX_DF))
                 overhead = 0;
@@ -1104,7 +1106,7 @@ static int ext2_statfs (struct dentry * dentry, struct kstatfs * buf)
                  * All of the blocks before first_data_block are
                  * overhead
                  */
-                overhead = le32_to_cpu(sbi->s_es->s_first_data_block);
+                overhead = le32_to_cpu(es->s_first_data_block);
 
                 /*
                  * Add the overhead attributed to the superblock and
@@ -1125,14 +1127,18 @@ static int ext2_statfs (struct dentry * dentry, struct kstatfs * buf)
 
         buf->f_type = EXT2_SUPER_MAGIC;
         buf->f_bsize = sb->s_blocksize;
-        buf->f_blocks = le32_to_cpu(sbi->s_es->s_blocks_count) - overhead;
+        buf->f_blocks = le32_to_cpu(es->s_blocks_count) - overhead;
         buf->f_bfree = ext2_count_free_blocks(sb);
-        buf->f_bavail = buf->f_bfree - le32_to_cpu(sbi->s_es->s_r_blocks_count);
-        if (buf->f_bfree < le32_to_cpu(sbi->s_es->s_r_blocks_count))
+        buf->f_bavail = buf->f_bfree - le32_to_cpu(es->s_r_blocks_count);
+        if (buf->f_bfree < le32_to_cpu(es->s_r_blocks_count))
                 buf->f_bavail = 0;
-        buf->f_files = le32_to_cpu(sbi->s_es->s_inodes_count);
-        buf->f_ffree = ext2_count_free_inodes (sb);
+        buf->f_files = le32_to_cpu(es->s_inodes_count);
+        buf->f_ffree = ext2_count_free_inodes(sb);
         buf->f_namelen = EXT2_NAME_LEN;
+        fsid = le64_to_cpup((void *)es->s_uuid) ^
+               le64_to_cpup((void *)es->s_uuid + sizeof(u64));
+        buf->f_fsid.val[0] = fsid & 0xFFFFFFFFUL;
+        buf->f_fsid.val[1] = (fsid >> 32) & 0xFFFFFFFFUL;
         return 0;
 }