Commit b5a7c4f5 authored by Glauber de Oliveira Costa's avatar Glauber de Oliveira Costa Committed by Linus Torvalds
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[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: default avatarGlauber 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: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent d3561f78

fs/ext3/balloc.c

+33 −7
Original line number Diff line number Diff line
@@ -1493,12 +1493,33 @@ static int ext3_group_sparse(int group) 
 */

int ext3_bg_has_super(struct super_block *sb, int group)

{

	if (EXT3_HAS_RO_COMPAT_FEATURE(sb,EXT3_FEATURE_RO_COMPAT_SPARSE_SUPER)&&

	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 @@ int ext3_bg_has_super(struct super_block *sb, int group) 
 */

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);



}

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