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Subject[29/90] ext4: Fix initalization of s_flex_groups
2.6.31-stable review patch.  If anyone has any objections, please let us know.

(cherry picked from commit 7ad9bb651fc2036ea94bed94da76a4b08959a911)

The s_flex_groups array should have been initialized using atomic_add
to sum up the free counts from the block groups that make up a
flex_bg. By using atomic_set, the value of the s_flex_groups array
was set to the values of the last block group in the flex_bg.

The impact of this bug is that the block and inode allocation
algorithms might not pick the best flex_bg for new allocation.

Thanks to Damien Guibouret for pointing out this problem!

Signed-off-by: "Theodore Ts'o" <>
Signed-off-by: Greg Kroah-Hartman <>
fs/ext4/super.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)

--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1696,12 +1696,12 @@ static int ext4_fill_flex_info(struct su
gdp = ext4_get_group_desc(sb, i, NULL);

flex_group = ext4_flex_group(sbi, i);
- atomic_set(&sbi->s_flex_groups[flex_group].free_inodes,
- ext4_free_inodes_count(sb, gdp));
- atomic_set(&sbi->s_flex_groups[flex_group].free_blocks,
- ext4_free_blks_count(sb, gdp));
- atomic_set(&sbi->s_flex_groups[flex_group].used_dirs,
- ext4_used_dirs_count(sb, gdp));
+ atomic_add(ext4_free_inodes_count(sb, gdp),
+ &sbi->s_flex_groups[flex_group].free_inodes);
+ atomic_add(ext4_free_blks_count(sb, gdp),
+ &sbi->s_flex_groups[flex_group].free_blocks);
+ atomic_add(ext4_used_dirs_count(sb, gdp),
+ &sbi->s_flex_groups[flex_group].used_dirs);

return 1;

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