reiserfs: ignore on disk s_bmap_nr value

Implement support for file systems larger than 8 TiB.

The reiserfs superblock contains a 16 bit value for counting the number of
bitmap blocks.  The rest of the disk format supports file systems up to 2^32
blocks, but the bitmap block limitation artificially limits this to 8 TiB with
a 4KiB block size.

Rather than trust the superblock's 16-bit bitmap block count, we calculate it
dynamically based on the number of blocks in the file system.  When an
incorrect value is observed in the superblock, it is zeroed out, ensuring that
older kernels will not be able to mount the file system.

Userspace support has already been implemented and shipped in reiserfsprogs
3.6.20.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 3 insertions, 3 deletions

diff --git a/fs/reiserfs/journal.c b/fs/reiserfs/journal.c
index 0e30ba0ac489..bb05a3e51b93 100644
--- a/fs/reiserfs/journal.c
+++ b/fs/reiserfs/journal.c
@@ -240,7 +240,7 @@ static void cleanup_bitmap_list(struct super_block *p_s_sb,
         if (jb->bitmaps == NULL)
                 return;
 
-        for (i = 0; i < SB_BMAP_NR(p_s_sb); i++) {
+        for (i = 0; i < reiserfs_bmap_count(p_s_sb); i++) {
                 if (jb->bitmaps[i]) {
                         free_bitmap_node(p_s_sb, jb->bitmaps[i]);
                         jb->bitmaps[i] = NULL;
@@ -2734,7 +2734,7 @@ int journal_init(struct super_block *p_s_sb, const char *j_dev_name,
         journal->j_persistent_trans = 0;
         if (reiserfs_allocate_list_bitmaps(p_s_sb,
                                            journal->j_list_bitmap,
-                                           SB_BMAP_NR(p_s_sb)))
+                                           reiserfs_bmap_count(p_s_sb)))
                 goto free_and_return;
         allocate_bitmap_nodes(p_s_sb);
 
@@ -2742,7 +2742,7 @@ int journal_init(struct super_block *p_s_sb, const char *j_dev_name,
         SB_JOURNAL_1st_RESERVED_BLOCK(p_s_sb) = (old_format ?
                                                  REISERFS_OLD_DISK_OFFSET_IN_BYTES
                                                  / p_s_sb->s_blocksize +
-                                                 SB_BMAP_NR(p_s_sb) +
+                                                 reiserfs_bmap_count(p_s_sb) +
                                                  1 :
                                                  REISERFS_DISK_OFFSET_IN_BYTES /
                                                  p_s_sb->s_blocksize + 2);