2012-10-25 16:59:04

by Eric Sandeen

Subject: [PATCH] ext4: fix overhead calculations in ext4_stats, again

"overhead" was a write-only variable in this function after commit
952fc18e; we set it to 0 for minixdf, or to sbi->s_overhead if !minixdf,
but never read it again after that.

We need to use it, not sbi->s_overhead, when subtracting out overhead
for f_blocks, or we get the wrong answer for minixdf.

Signed-off-by: Eric Sandeen <[email protected]>
---

"Once more, with feeling!" ;)

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index e44b233..2feaf78 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -4758,7 +4758,7 @@ static int ext4_statfs(struct dentry *dentry, struct kstatfs *buf)

buf->f_type = EXT4_SUPER_MAGIC;
buf->f_bsize = sb->s_blocksize;
- buf->f_blocks = ext4_blocks_count(es) - EXT4_C2B(sbi, sbi->s_overhead);
+ buf->f_blocks = ext4_blocks_count(es) - EXT4_C2B(sbi, overhead);
bfree = percpu_counter_sum_positive(&sbi->s_freeclusters_counter) -
percpu_counter_sum_positive(&sbi->s_dirtyclusters_counter);
/* prevent underflow in case that few free space is available */

2012-10-25 17:14:26

by Eric Sandeen

Subject: Re: [PATCH] ext4: fix overhead calculations in ext4_statfs, again

sorry that should be "ext4_statfs" in the subject.

On 10/25/12 11:59 AM, Eric Sandeen wrote:
> "overhead" was a write-only variable in this function after commit
> 952fc18e; we set it to 0 for minixdf, or to sbi->s_overhead if !minixdf,
> but never read it again after that.
>
> We need to use it, not sbi->s_overhead, when subtracting out overhead
> for f_blocks, or we get the wrong answer for minixdf.
>
> Signed-off-by: Eric Sandeen <[email protected]>
> ---
>
> "Once more, with feeling!" ;)
>
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index e44b233..2feaf78 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -4758,7 +4758,7 @@ static int ext4_statfs(struct dentry *dentry, struct kstatfs *buf)
>
> buf->f_type = EXT4_SUPER_MAGIC;
> buf->f_bsize = sb->s_blocksize;
> - buf->f_blocks = ext4_blocks_count(es) - EXT4_C2B(sbi, sbi->s_overhead);
> + buf->f_blocks = ext4_blocks_count(es) - EXT4_C2B(sbi, overhead);
> bfree = percpu_counter_sum_positive(&sbi->s_freeclusters_counter) -
> percpu_counter_sum_positive(&sbi->s_dirtyclusters_counter);
> /* prevent underflow in case that few free space is available */
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
> the body of a message to [email protected]
> More majordomo info at http://vger.kernel.org/majordomo-info.html
>

2012-10-29 17:13:59

by Jan Kara

Subject: Re: [PATCH] ext4: fix overhead calculations in ext4_stats, again

On Thu 25-10-12 11:59:02, Eric Sandeen wrote:
> "overhead" was a write-only variable in this function after commit
> 952fc18e; we set it to 0 for minixdf, or to sbi->s_overhead if !minixdf,
> but never read it again after that.
>
> We need to use it, not sbi->s_overhead, when subtracting out overhead
> for f_blocks, or we get the wrong answer for minixdf.
>
> Signed-off-by: Eric Sandeen <[email protected]>
Yeah, looks good. You can add:
Reviewed-by: Jan Kara <[email protected]>

Honza
> ---
>
> "Once more, with feeling!" ;)
>
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index e44b233..2feaf78 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -4758,7 +4758,7 @@ static int ext4_statfs(struct dentry *dentry, struct kstatfs *buf)
>
> buf->f_type = EXT4_SUPER_MAGIC;
> buf->f_bsize = sb->s_blocksize;
> - buf->f_blocks = ext4_blocks_count(es) - EXT4_C2B(sbi, sbi->s_overhead);
> + buf->f_blocks = ext4_blocks_count(es) - EXT4_C2B(sbi, overhead);
> bfree = percpu_counter_sum_positive(&sbi->s_freeclusters_counter) -
> percpu_counter_sum_positive(&sbi->s_dirtyclusters_counter);
> /* prevent underflow in case that few free space is available */
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
> the body of a message to [email protected]
> More majordomo info at http://vger.kernel.org/majordomo-info.html
--
Jan Kara <[email protected]>
SUSE Labs, CR

2012-11-08 22:11:01

by Theodore Ts'o

Subject: Re: [PATCH] ext4: fix overhead calculations in ext4_stats, again

On Thu, Oct 25, 2012 at 11:59:02AM -0500, Eric Sandeen wrote:
> "overhead" was a write-only variable in this function after commit
> 952fc18e; we set it to 0 for minixdf, or to sbi->s_overhead if !minixdf,
> but never read it again after that.
>
> We need to use it, not sbi->s_overhead, when subtracting out overhead
> for f_blocks, or we get the wrong answer for minixdf.
>
> Signed-off-by: Eric Sandeen <[email protected]>

Thanks, applied.

- Ted