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ext4: fix overhead calculations in ext4_stats, again

PATCH Applied Eric Sandeen 3 participants 4 messages Oct 25, 2012 – Nov 8, 2012 ext4 file system

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Eric Sandeen

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#0 lore raw

PATCH 1/1 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!" ;)

fs/ext4/super.c +1 -1
index e44b233..2feaf78 100644
@@ -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 */
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#1 lore raw

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

sorry that should be "ext4_statfs" in the subject.

Quoted 31 lines · Eric Sandeen

"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!" ;)

fs/ext4/super.c +1 -2
index e44b233..2feaf78 100644
@@ -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 */
 
--

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reviewer Reviewed-by on v1 1/1
#2 lore raw
In reply to Eric Sandeen
Quoted 8 lines · Eric Sandeen

"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

Quoted 22 lines

---

"Once more, with feeling!" ;)

fs/ext4/super.c +1 -2
index e44b233..2feaf78 100644
@@ -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 */
 
--

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Signature · 2 lines
Jan Kara <[email protected]>
SUSE Labs, CR
maintainer Applied
#3 lore raw
In reply to Eric Sandeen
Quoted 8 lines · Eric Sandeen

"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