[PATCH v2] zonefs: fix page reference and BIO leak

[PATCH v2] zonefs: fix page reference and BIO leak

[Damien Le Moal]

In zonefs_file_dio_append(), the pages obtained using
bio_iov_iter_get_pages() are not released on completion of the
REQ_OP_APPEND BIO, nor when bio_iov_iter_get_pages() fails.
Furthermore, a call to bio_put() is missing when
bio_iov_iter_get_pages() fails.

Fix these resource leaks by adding BIO resource release code (bio_put()i
and bio_release_pages()) at the end of the function after the BIO
execution and add a jump to this resource cleanup code in case of
bio_iov_iter_get_pages() failure.

While at it, also fix the call to task_io_account_write() to be passed
the correct BIO size instead of bio_iov_iter_get_pages() return value.

Reported-by: Christoph Hellwig <hch@lst.de>
Fixes: 02ef12a663c7 ("zonefs: use REQ_OP_ZONE_APPEND for sync DIO")
Cc: stable@vger.kernel.org
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
---
 fs/zonefs/super.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/fs/zonefs/super.c b/fs/zonefs/super.c
index ff5930be096c..bec47f2d074b 100644
--- a/fs/zonefs/super.c
+++ b/fs/zonefs/super.c
@@ -691,21 +691,23 @@ static ssize_t zonefs_file_dio_append(struct kiocb *iocb, struct iov_iter *from)
 		bio->bi_opf |= REQ_FUA;
 
 	ret = bio_iov_iter_get_pages(bio, from);
-	if (unlikely(ret)) {
-		bio_io_error(bio);
-		return ret;
-	}
+	if (unlikely(ret))
+		goto out_release;
+
 	size = bio->bi_iter.bi_size;
-	task_io_account_write(ret);
+	task_io_account_write(size);
 
 	if (iocb->ki_flags & IOCB_HIPRI)
 		bio_set_polled(bio, iocb);
 
 	ret = submit_bio_wait(bio);
 
+	zonefs_file_write_dio_end_io(iocb, size, ret, 0);
+
+out_release:
+	bio_release_pages(bio, false);
 	bio_put(bio);
 
-	zonefs_file_write_dio_end_io(iocb, size, ret, 0);
 	if (ret >= 0) {
 		iocb->ki_pos += size;
 		return size;
-- 
2.28.0

Re: [PATCH v2] zonefs: fix page reference and BIO leak

[Chaitanya Kulkarni]

On 12/9/20 17:41, Damien Le Moal wrote:
> In zonefs_file_dio_append(), the pages obtained using
> bio_iov_iter_get_pages() are not released on completion of the
> REQ_OP_APPEND BIO, nor when bio_iov_iter_get_pages() fails.
> Furthermore, a call to bio_put() is missing when
> bio_iov_iter_get_pages() fails.
>
> Fix these resource leaks by adding BIO resource release code (bio_put()i
I think extra 'i' above needs to be removed at the time of applying the
patch.
> and bio_release_pages()) at the end of the function after the BIO
> execution and add a jump to this resource cleanup code in case of
> bio_iov_iter_get_pages() failure.
>
> While at it, also fix the call to task_io_account_write() to be passed
> the correct BIO size instead of bio_iov_iter_get_pages() return value.
>
> Reported-by: Christoph Hellwig <hch@lst.de>
> Fixes: 02ef12a663c7 ("zonefs: use REQ_OP_ZONE_APPEND for sync DIO")
> Cc: stable@vger.kernel.org
> Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Looks good.

Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>

Re: [PATCH v2] zonefs: fix page reference and BIO leak

[Christoph Hellwig]

Looks good,

Reviewed-by: Christoph Hellwig <hch@lst.de>

Re: [PATCH v2] zonefs: fix page reference and BIO leak

[Johannes Thumshirn]

On 10/12/2020 02:38, Damien Le Moal wrote:
> In zonefs_file_dio_append(), the pages obtained using
> bio_iov_iter_get_pages() are not released on completion of the
> REQ_OP_APPEND BIO, nor when bio_iov_iter_get_pages() fails.
> Furthermore, a call to bio_put() is missing when
> bio_iov_iter_get_pages() fails.
> 
> Fix these resource leaks by adding BIO resource release code (bio_put()i
> and bio_release_pages()) at the end of the function after the BIO
> execution and add a jump to this resource cleanup code in case of
> bio_iov_iter_get_pages() failure.
> 
> While at it, also fix the call to task_io_account_write() to be passed
> the correct BIO size instead of bio_iov_iter_get_pages() return value.
> 
> Reported-by: Christoph Hellwig <hch@lst.de>
> Fixes: 02ef12a663c7 ("zonefs: use REQ_OP_ZONE_APPEND for sync DIO")
> Cc: stable@vger.kernel.org
> Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
> ---
>  fs/zonefs/super.c | 14 ++++++++------
>  1 file changed, 8 insertions(+), 6 deletions(-)
> 
> diff --git a/fs/zonefs/super.c b/fs/zonefs/super.c
> index ff5930be096c..bec47f2d074b 100644
> --- a/fs/zonefs/super.c
> +++ b/fs/zonefs/super.c
> @@ -691,21 +691,23 @@ static ssize_t zonefs_file_dio_append(struct kiocb *iocb, struct iov_iter *from)
>  		bio->bi_opf |= REQ_FUA;
>  
>  	ret = bio_iov_iter_get_pages(bio, from);
> -	if (unlikely(ret)) {
> -		bio_io_error(bio);
> -		return ret;
> -	}
> +	if (unlikely(ret))
> +		goto out_release;
> +
>  	size = bio->bi_iter.bi_size;
> -	task_io_account_write(ret);
> +	task_io_account_write(size);
>  
>  	if (iocb->ki_flags & IOCB_HIPRI)
>  		bio_set_polled(bio, iocb);
>  
>  	ret = submit_bio_wait(bio);
>  
> +	zonefs_file_write_dio_end_io(iocb, size, ret, 0);
> +
> +out_release:
> +	bio_release_pages(bio, false);
>  	bio_put(bio);
>  
> -	zonefs_file_write_dio_end_io(iocb, size, ret, 0);
>  	if (ret >= 0) {
>  		iocb->ki_pos += size;
>  		return size;
> 

Aren't we loosing bio->bi_status = BLK_STS_IOERR in case bio_iov_iter_get_pages() fails now?

Re: [PATCH v2] zonefs: fix page reference and BIO leak

[Christoph Hellwig]

On Thu, Dec 10, 2020 at 07:03:08AM +0000, Johannes Thumshirn wrote:
> Aren't we loosing bio->bi_status = BLK_STS_IOERR in case bio_iov_iter_get_pages() fails now?

We do, but it does not matter because nothing actually looks at
->bi_status in this failure path.

Re: [PATCH v2] zonefs: fix page reference and BIO leak

[Johannes Thumshirn]

On 10/12/2020 08:06, Christoph Hellwig wrote:
> On Thu, Dec 10, 2020 at 07:03:08AM +0000, Johannes Thumshirn wrote:
>> Aren't we loosing bio->bi_status = BLK_STS_IOERR in case bio_iov_iter_get_pages() fails now?
> 
> We do, but it does not matter because nothing actually looks at
> ->bi_status in this failure path.
> 

Right we never pass the bio to the block layer in the error case.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>