[PATCH] ext4: allow larger descriptor size

make block group descriptor larger.

Signed-off-by: Alexandre Ratchov <alexandre.ratchov@bull.net>
Signed-off-by: Dave Kleikamp <shaggy@austin.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 7 insertions, 3 deletions

diff --git a/include/linux/ext4_fs.h b/include/linux/ext4_fs.h
index 8e5009ee4ad8..a3df2afc004b 100644
--- a/include/linux/ext4_fs.h
+++ b/include/linux/ext4_fs.h
@@ -142,6 +142,9 @@ struct ext4_group_desc
 /*
  * Macro-instructions used to manage group descriptors
  */
+#define EXT4_MIN_DESC_SIZE              32
+#define EXT4_MAX_DESC_SIZE              EXT4_MIN_BLOCK_SIZE
+#define EXT4_DESC_SIZE(s)               (EXT4_SB(s)->s_desc_size)
 #ifdef __KERNEL__
 # define EXT4_BLOCKS_PER_GROUP(s)       (EXT4_SB(s)->s_blocks_per_group)
 # define EXT4_DESC_PER_BLOCK(s)         (EXT4_SB(s)->s_desc_per_block)
@@ -149,7 +152,7 @@ struct ext4_group_desc
 # define EXT4_DESC_PER_BLOCK_BITS(s)    (EXT4_SB(s)->s_desc_per_block_bits)
 #else
 # define EXT4_BLOCKS_PER_GROUP(s)       ((s)->s_blocks_per_group)
-# define EXT4_DESC_PER_BLOCK(s)         (EXT4_BLOCK_SIZE(s) / sizeof (struct ext4_group_desc))
+# define EXT4_DESC_PER_BLOCK(s)         (EXT4_BLOCK_SIZE(s) / EXT4_DESC_SIZE(s))
 # define EXT4_INODES_PER_GROUP(s)       ((s)->s_inodes_per_group)
 #endif
 
@@ -474,7 +477,7 @@ struct ext4_super_block {
          * things it doesn't understand...
          */
         __le32  s_first_ino;            /* First non-reserved inode */
-        __le16   s_inode_size;          /* size of inode structure */
+        __le16  s_inode_size;           /* size of inode structure */
         __le16  s_block_group_nr;       /* block group # of this superblock */
         __le32  s_feature_compat;       /* compatible feature set */
 /*60*/  __le32  s_feature_incompat;     /* incompatible feature set */
@@ -500,7 +503,7 @@ struct ext4_super_block {
         __le32  s_hash_seed[4];         /* HTREE hash seed */
         __u8    s_def_hash_version;     /* Default hash version to use */
         __u8    s_reserved_char_pad;
-        __u16   s_reserved_word_pad;
+        __le16  s_desc_size;            /* size of group descriptor */
 /*100*/ __le32  s_default_mount_opts;
         __le32  s_first_meta_bg;        /* First metablock block group */
         __le32  s_mkfs_time;            /* When the filesystem was created */
diff --git a/include/linux/ext4_fs_sb.h b/include/linux/ext4_fs_sb.h
index ce7a844d6703..691a713139ce 100644
--- a/include/linux/ext4_fs_sb.h
+++ b/include/linux/ext4_fs_sb.h
@@ -29,6 +29,7 @@
  */
 struct ext4_sb_info {
         unsigned long s_frag_size;      /* Size of a fragment in bytes */
+        unsigned long s_desc_size;      /* Size of a group descriptor in bytes */
         unsigned long s_frags_per_block;/* Number of fragments per block */
         unsigned long s_inodes_per_block;/* Number of inodes per block */
         unsigned long s_frags_per_group;/* Number of fragments in a group */