* [PATCH] ext4: Fix handle refcount leak in ext4_write_begin()
@ 2021-09-08 7:06 Chenyuan Mi
2021-10-07 14:06 ` Jan Kara
0 siblings, 1 reply; 2+ messages in thread
From: Chenyuan Mi @ 2021-09-08 7:06 UTC (permalink / raw)
Cc: yuanxzhang, Chenyuan Mi, Xiyu Yang, Xin Tan, Theodore Ts'o,
Andreas Dilger, linux-ext4, linux-kernel
The reference counting issue happens when ret is zero,
the function forgets to decrease the refcount of handle
increased by ext4_journal_start().
Fix this issue by using ext4_journal_stop() to decrease
the refcount of handle.
Signed-off-by: Chenyuan Mi <cymi20@fudan.edu.cn>
Signed-off-by: Xiyu Yang <xiyuyang19@fudan.edu.cn>
Signed-off-by: Xin Tan <tanxin.ctf@gmail.com>
---
fs/ext4/inode.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index d18852d6029c..90c57d8e3de1 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1249,6 +1249,7 @@ static int ext4_write_begin(struct file *file, struct address_space *mapping,
put_page(page);
return ret;
}
+ ext4_journal_stop(handle);
*pagep = page;
return ret;
}
--
2.17.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] ext4: Fix handle refcount leak in ext4_write_begin()
2021-09-08 7:06 [PATCH] ext4: Fix handle refcount leak in ext4_write_begin() Chenyuan Mi
@ 2021-10-07 14:06 ` Jan Kara
0 siblings, 0 replies; 2+ messages in thread
From: Jan Kara @ 2021-10-07 14:06 UTC (permalink / raw)
To: Chenyuan Mi
Cc: yuanxzhang, Xiyu Yang, Xin Tan, Theodore Ts'o,
Andreas Dilger, linux-ext4, linux-kernel
On Wed 08-09-21 15:06:40, Chenyuan Mi wrote:
> The reference counting issue happens when ret is zero,
> the function forgets to decrease the refcount of handle
> increased by ext4_journal_start().
>
> Fix this issue by using ext4_journal_stop() to decrease
> the refcount of handle.
>
> Signed-off-by: Chenyuan Mi <cymi20@fudan.edu.cn>
> Signed-off-by: Xiyu Yang <xiyuyang19@fudan.edu.cn>
> Signed-off-by: Xin Tan <tanxin.ctf@gmail.com>
Yes, but that is deliberate. We want to keep the transaction running until
the write is done - i.e., until ->write_end() callback where we call
ext4_journal_stop(). As a side note, please test your patches. You clearly
didn't test this patch because if you did, you would notice that your patch
breaks writing to ext4.
Honza
> ---
> fs/ext4/inode.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index d18852d6029c..90c57d8e3de1 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -1249,6 +1249,7 @@ static int ext4_write_begin(struct file *file, struct address_space *mapping,
> put_page(page);
> return ret;
> }
> + ext4_journal_stop(handle);
> *pagep = page;
> return ret;
> }
> --
> 2.17.1
>
--
Jan Kara <jack@suse.com>
SUSE Labs, CR
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