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authorDarrick J. Wong <darrick.wong@oracle.com>2014-05-12 10:06:27 -0400
committerTheodore Ts'o <tytso@mit.edu>2014-05-12 10:06:27 -0400
commitbd63f6b0cd577e94846869db0c86a7b2bee79b26 (patch)
tree0ed548caaaacd22a93dbf018768e6497e3df7b34 /fs/ext4
parent230b8c1a7b388ac5e06549a7dbe083568875804e (diff)
ext4: find the group descriptors on a 1k-block bigalloc,meta_bg filesystem
On a filesystem with a 1k block size, the group descriptors live in block 2, not block 1. If the filesystem has bigalloc,meta_bg set, however, the calculation of the group descriptor table location does not take this into account and returns the wrong block number. Fix the calculation to return the correct value for this case. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Diffstat (limited to 'fs/ext4')
-rw-r--r--fs/ext4/super.c10
1 files changed, 10 insertions, 0 deletions
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 1f8cb1812723..e38dd7d37a69 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -2405,6 +2405,16 @@ static ext4_fsblk_t descriptor_loc(struct super_block *sb,
if (ext4_bg_has_super(sb, bg))
has_super = 1;
+ /*
+ * If we have a meta_bg fs with 1k blocks, group 0's GDT is at
+ * block 2, not 1. If s_first_data_block == 0 (bigalloc is enabled
+ * on modern mke2fs or blksize > 1k on older mke2fs) then we must
+ * compensate.
+ */
+ if (sb->s_blocksize == 1024 && nr == 0 &&
+ le32_to_cpu(EXT4_SB(sb)->s_es->s_first_data_block) == 0)
+ has_super++;
+
return (has_super + ext4_group_first_block_no(sb, bg));
}