[PATCH] ext3: Properly report backup block present in a group
In filesystems with the meta block group flag on, ext3_bg_num_gdb() fails
to report the correct number of blocks used to store the group descriptor
backups in a given group. It happens because meta_bg follows a different
logic from the original ext3 backup placement in groups multiples of 3, 5
and 7.
Signed-off-by: Glauber de Oliveira Costa <glommer@br.ibm.com>
Cc: Andreas Dilger <adilger@clusterfs.com>
Cc: "Stephen C. Tweedie" <sct@redhat.com>
Cc: Alex Tomas <alex@clusterfs.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/fs/ext3/balloc.c b/fs/ext3/balloc.c
index 6250fcd..46623f7 100644
--- a/fs/ext3/balloc.c
+++ b/fs/ext3/balloc.c
@@ -1493,12 +1493,33 @@
*/
int ext3_bg_has_super(struct super_block *sb, int group)
{
- if (EXT3_HAS_RO_COMPAT_FEATURE(sb,EXT3_FEATURE_RO_COMPAT_SPARSE_SUPER)&&
- !ext3_group_sparse(group))
+ if (EXT3_HAS_RO_COMPAT_FEATURE(sb,
+ EXT3_FEATURE_RO_COMPAT_SPARSE_SUPER) &&
+ !ext3_group_sparse(group))
return 0;
return 1;
}
+static unsigned long ext3_bg_num_gdb_meta(struct super_block *sb, int group)
+{
+ unsigned long metagroup = group / EXT3_DESC_PER_BLOCK(sb);
+ unsigned long first = metagroup * EXT3_DESC_PER_BLOCK(sb);
+ unsigned long last = first + EXT3_DESC_PER_BLOCK(sb) - 1;
+
+ if (group == first || group == first + 1 || group == last)
+ return 1;
+ return 0;
+}
+
+static unsigned long ext3_bg_num_gdb_nometa(struct super_block *sb, int group)
+{
+ if (EXT3_HAS_RO_COMPAT_FEATURE(sb,
+ EXT3_FEATURE_RO_COMPAT_SPARSE_SUPER) &&
+ !ext3_group_sparse(group))
+ return 0;
+ return EXT3_SB(sb)->s_gdb_count;
+}
+
/**
* ext3_bg_num_gdb - number of blocks used by the group table in group
* @sb: superblock for filesystem
@@ -1510,9 +1531,14 @@
*/
unsigned long ext3_bg_num_gdb(struct super_block *sb, int group)
{
- if (EXT3_HAS_RO_COMPAT_FEATURE(sb,EXT3_FEATURE_RO_COMPAT_SPARSE_SUPER)&&
- !ext3_group_sparse(group))
- return 0;
- return EXT3_SB(sb)->s_gdb_count;
-}
+ unsigned long first_meta_bg =
+ le32_to_cpu(EXT3_SB(sb)->s_es->s_first_meta_bg);
+ unsigned long metagroup = group / EXT3_DESC_PER_BLOCK(sb);
+ if (!EXT3_HAS_INCOMPAT_FEATURE(sb,EXT3_FEATURE_INCOMPAT_META_BG) ||
+ metagroup < first_meta_bg)
+ return ext3_bg_num_gdb_nometa(sb,group);
+
+ return ext3_bg_num_gdb_meta(sb,group);
+
+}