ext4: Fix the loop condition in ext4_mb_free_committed_blocks

Since md is freed before the do-while checks it,
it's better to change it to while(1).

Signed-off-by Shen Feng <[email protected]>

---
 fs/ext4/mballoc.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

fs/ext4/mballoc.c +1 -1

index 42553f6..063f820 100644
@@ -2572,7 +2572,7 @@ ext4_mb_free_committed_blocks(struct super_block *sb)
 		kfree(md);
 		ext4_mb_release_desc(&e4b);
 
-	} while (md);
+	} while (1);
 
 	mb_debug("freed %u blocks in %u structures\n", count, count2);
 }

Signature · 5 lines

1.5.4.5
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Since md is freed before the do-while checks it,
it's better to change it to while(1).

Quoted 3 lines

Since md is freed before the do-while checks it,
it's better to change it to while(1).

This actually isn't a bug, since there is no problem checking a pointer that has been freed; its only *dereferencing* a pointer which is bad. That being said, md is never NULL at the end of the loop, since in the middle of the loop is the only break condition:

	if (md == NULL)
		break;

So the patch saves a tiny amount of compiled code, but it isn't really a fix in any way.

That being said, if we're going to make this sort of change, my preference would be to use the more common C idiom:

	while (1) {
	      ...
	}

as opposed to

	do {
	      ...
	} while (1);

The former makes it quite clear that any exit from the loop is not going to be coming from loop construct itself, but from any embedded break statements inside the loop construct