Commit 5c1ff336 authored by Eric Whitney's avatar Eric Whitney Committed by Theodore Ts'o
Browse files

ext4: fix free space estimate in ext4_nonda_switch() 



Values stored in s_freeclusters_counter and s_dirtyclusters_counter
are both in cluster units.  Remove the cluster to block conversion
applied to s_freeclusters_counter causing an inflated estimate of
free space because s_dirtyclusters_counter is not similarly
converted.  Rename free_blocks and dirty_blocks to better reflect
the units these variables contain to avoid future confusion.  This
fix corrects ENOSPC failures for xfstests 127 and 231 on bigalloc
file systems.

Signed-off-by: default avatarEric Whitney <enwlinux@gmail.com>
Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent bcb13850

fs/ext4/inode.c

+8 −7
Original line number Diff line number Diff line
@@ -2609,7 +2609,7 @@ out_writepages: 


static int ext4_nonda_switch(struct super_block *sb)

{

	s64 free_blocks, dirty_blocks;

	s64 free_clusters, dirty_clusters;

	struct ext4_sb_info *sbi = EXT4_SB(sb);



	/*
@@ -2620,17 +2620,18 @@ static int ext4_nonda_switch(struct super_block *sb) 
	 * Delalloc need an accurate free block accounting. So switch

	 * to non delalloc when we are near to error range.

	 */

	free_blocks  = EXT4_C2B(sbi,

		percpu_counter_read_positive(&sbi->s_freeclusters_counter));

	dirty_blocks = percpu_counter_read_positive(&sbi->s_dirtyclusters_counter);

	free_clusters =

		percpu_counter_read_positive(&sbi->s_freeclusters_counter);

	dirty_clusters =

		percpu_counter_read_positive(&sbi->s_dirtyclusters_counter);

	/*

	 * Start pushing delalloc when 1/2 of free blocks are dirty.

	 */

	if (dirty_blocks && (free_blocks < 2 * dirty_blocks))

	if (dirty_clusters && (free_clusters < 2 * dirty_clusters))

		try_to_writeback_inodes_sb(sb, WB_REASON_FS_FREE_SPACE);



	if (2 * free_blocks < 3 * dirty_blocks ||

		free_blocks < (dirty_blocks + EXT4_FREECLUSTERS_WATERMARK)) {

	if (2 * free_clusters < 3 * dirty_clusters ||

	    free_clusters < (dirty_clusters + EXT4_FREECLUSTERS_WATERMARK)) {

		/*

		 * free block count is less than 150% of dirty blocks

		 * or free blocks is less than watermark

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