[PATCH] ext4: don't count external journal blocks as overhead

[PATCH] ext4: don't count external journal blocks as overhead

[Eric Sandeen]

This was fixed for ext3 with:

e6d8fb3 ext3: Count internal journal as bsddf overhead in ext3_statfs

but was never fixed for ext4.

With a large external journal and no used disk blocks, df comes
out negative without this, as journal blocks are added to the
overhead & subtracted from used blocks unconditionally.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
---

ps: since this is stored in the on-disk superblock now, I'm not
sure how to fix up old filesystems, or if it matters much.

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 2c9e686..9674578 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -3338,8 +3338,8 @@ int ext4_calculate_overhead(struct super_block *sb)
 			memset(buf, 0, PAGE_SIZE);
 		cond_resched();
 	}
-	/* Add the journal blocks as well */
-	if (sbi->s_journal)
+	/* Add the internal journal blocks as well */
+	if (sbi->s_journal && !sbi->journal_bdev)
 		overhead += EXT4_NUM_B2C(sbi, sbi->s_journal->j_maxlen);
 
 	sbi->s_overhead = overhead;

Re: [PATCH] ext4: don't count external journal blocks as overhead

[Theodore Ts'o]

On Fri, Nov 14, 2014 at 12:39:47PM -0600, Eric Sandeen wrote:
> This was fixed for ext3 with:
> 
> e6d8fb3 ext3: Count internal journal as bsddf overhead in ext3_statfs
> 
> but was never fixed for ext4.
> 
> With a large external journal and no used disk blocks, df comes
> out negative without this, as journal blocks are added to the
> overhead & subtracted from used blocks unconditionally.
> 
> Signed-off-by: Eric Sandeen <sandeen@redhat.com>

Thanks, applied.

					- Ted