ext4: Fix initalization of s_flex_groups (7ad9bb65) · Commits · 戴 / test

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>

fs/ext4/super.c

+6 −6

Original line number	Diff line number	Diff line
		@@ -1694,12 +1694,12 @@ static int ext4_fill_flex_info(struct super_block *sb)
		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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