* [PATCH] Btrfs: make sure there is always room for generation number
@ 2018-07-03 0:00 Zhihui Zhang
2018-07-04 15:14 ` David Sterba
2018-07-04 15:21 ` David Sterba
0 siblings, 2 replies; 4+ messages in thread
From: Zhihui Zhang @ 2018-07-03 0:00 UTC (permalink / raw)
To: jbacik, dsterba; +Cc: linux-btrfs
io_ctl_set_generation() assumes that the generation number shares
the same page with inline CRCs. Let's make sure this is always true.
Signed-off-by: Zhihui Zhang <zzhsuny@gmail.com>
---
fs/btrfs/free-space-cache.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index d5f80cb300be..9aa0fbf16515 100644
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -300,9 +300,9 @@ static int io_ctl_init(struct btrfs_io_ctl *io_ctl, struct inode *inode,
if (btrfs_ino(BTRFS_I(inode)) != BTRFS_FREE_INO_OBJECTID)
check_crcs = 1;
- /* Make sure we can fit our crcs into the first page */
+ /* Make sure we can fit our crcs and generation # into the first page */
if (write && check_crcs &&
- (num_pages * sizeof(u32)) >= PAGE_SIZE)
+ (num_pages * sizeof(u32) + sizeof(u64)) > PAGE_SIZE)
return -ENOSPC;
memset(io_ctl, 0, sizeof(struct btrfs_io_ctl));
--
2.17.1
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] Btrfs: make sure there is always room for generation number
2018-07-03 0:00 [PATCH] Btrfs: make sure there is always room for generation number Zhihui Zhang
@ 2018-07-04 15:14 ` David Sterba
2018-07-04 15:21 ` David Sterba
1 sibling, 0 replies; 4+ messages in thread
From: David Sterba @ 2018-07-04 15:14 UTC (permalink / raw)
To: Zhihui Zhang; +Cc: jbacik, dsterba, linux-btrfs
On Mon, Jul 02, 2018 at 08:00:54PM -0400, Zhihui Zhang wrote:
> io_ctl_set_generation() assumes that the generation number shares
> the same page with inline CRCs. Let's make sure this is always true.
Have you found this by code inspection or is it a fix for a bug that can
be reproduced?
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] Btrfs: make sure there is always room for generation number
2018-07-03 0:00 [PATCH] Btrfs: make sure there is always room for generation number Zhihui Zhang
2018-07-04 15:14 ` David Sterba
@ 2018-07-04 15:21 ` David Sterba
2018-07-05 12:40 ` Zhihui Zhang
1 sibling, 1 reply; 4+ messages in thread
From: David Sterba @ 2018-07-04 15:21 UTC (permalink / raw)
To: Zhihui Zhang; +Cc: jbacik, dsterba, linux-btrfs
On Mon, Jul 02, 2018 at 08:00:54PM -0400, Zhihui Zhang wrote:
> io_ctl_set_generation() assumes that the generation number shares
> the same page with inline CRCs. Let's make sure this is always true.
>
> Signed-off-by: Zhihui Zhang <zzhsuny@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.com>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] Btrfs: make sure there is always room for generation number
2018-07-04 15:21 ` David Sterba
@ 2018-07-05 12:40 ` Zhihui Zhang
0 siblings, 0 replies; 4+ messages in thread
From: Zhihui Zhang @ 2018-07-05 12:40 UTC (permalink / raw)
To: dsterba, Zhihui Zhang, jbacik, dsterba, linux-btrfs
code inspection. If I understand it correctly, we are off by 4 bytes
because CRC is 32 bits and generation is 64 bits. But this bug might
never hit in practice.
thanks,
-Zhihui
On Wed, Jul 4, 2018 at 11:21 AM, David Sterba <dsterba@suse.cz> wrote:
> On Mon, Jul 02, 2018 at 08:00:54PM -0400, Zhihui Zhang wrote:
>> io_ctl_set_generation() assumes that the generation number shares
>> the same page with inline CRCs. Let's make sure this is always true.
>>
>> Signed-off-by: Zhihui Zhang <zzhsuny@gmail.com>
>
> Reviewed-by: David Sterba <dsterba@suse.com>
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2018-07-05 12:40 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz follow: Atom feed
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2018-07-03 0:00 [PATCH] Btrfs: make sure there is always room for generation number Zhihui Zhang
2018-07-04 15:14 ` David Sterba
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2018-07-05 12:40 ` Zhihui Zhang
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