This is a note to let you know that I've just added the patch titled
zram: correct offset usage in zram_bio_discard
to the 3.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
zram-correct-offset-usage-in-zram_bio_discard.patch
and it can be found in the queue-3.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From 38515c73398a4c58059ecf1087e844561b58ee0f Mon Sep 17 00:00:00 2001
From: Weijie Yang <[email protected]>
Date: Wed, 4 Jun 2014 16:11:06 -0700
Subject: zram: correct offset usage in zram_bio_discard
From: Weijie Yang <[email protected]>
commit 38515c73398a4c58059ecf1087e844561b58ee0f upstream.
We want to skip the physical block(PAGE_SIZE) which is partially covered
by the discard bio, so we check the remaining size and subtract it if
there is a need to goto the next physical block.
The current offset usage in zram_bio_discard is incorrect, it will cause
its upper filesystem breakdown. Consider the following scenario:
On some architecture or config, PAGE_SIZE is 64K for example, filesystem
is set up on zram disk without PAGE_SIZE aligned, a discard bio leads to a
offset = 4K and size=72K, normally, it should not really discard any
physical block as it partially cover two physical blocks. However, with
the current offset usage, it will discard the second physical block and
free its memory, which will cause filesystem breakdown.
This patch corrects the offset usage in zram_bio_discard.
Signed-off-by: Weijie Yang <[email protected]>
Cc: Minchan Kim <[email protected]>
Cc: Nitin Gupta <[email protected]>
Acked-by: Joonsoo Kim <[email protected]>
Cc: Sergey Senozhatsky <[email protected]>
Cc: Bob Liu <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
drivers/block/zram/zram_drv.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -572,10 +572,10 @@ static void zram_bio_discard(struct zram
* skipping this logical block is appropriate here.
*/
if (offset) {
- if (n < offset)
+ if (n <= (PAGE_SIZE - offset))
return;
- n -= offset;
+ n -= (PAGE_SIZE - offset);
index++;
}
Patches currently in stable-queue which might be from [email protected]
are
queue-3.15/zram-correct-offset-usage-in-zram_bio_discard.patch
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