ext4: Fix initalization of s_flex_groups
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" <tytso@mit.edu>
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 9f6fa3f..04c6933 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1694,12 +1694,12 @@
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;