2024-01-29 09:50:32

by David Howells

Subject: [PATCH 1/2] netfs: Fix i_dio_count leak on DIO read past i_size

From: Marc Dionne <[email protected]>

If netfs_begin_read gets a NETFS_DIO_READ request that begins
past i_size, it won't perform any i/o and just return 0. This
will leak an increment to i_dio_count that is done at the top
of the function.

This can cause subsequent buffered read requests to block
indefinitely, waiting for a non existing dio operation to complete.

Add a inode_dio_end() for the NETFS_DIO_READ case, before returning.

Signed-off-by: Marc Dionne <[email protected]>
Signed-off-by: David Howells <[email protected]>
cc: Jeff Layton <[email protected]>
cc: [email protected]
cc: [email protected]
cc: [email protected]
---
fs/netfs/io.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/fs/netfs/io.c b/fs/netfs/io.c
index e8ff1e61ce79..4261ad6c55b6 100644
--- a/fs/netfs/io.c
+++ b/fs/netfs/io.c
@@ -748,6 +748,8 @@ int netfs_begin_read(struct netfs_io_request *rreq, bool sync)

if (!rreq->submitted) {
netfs_put_request(rreq, false, netfs_rreq_trace_put_no_submit);
+ if (rreq->origin == NETFS_DIO_READ)
+ inode_dio_end(rreq->inode);
ret = 0;
goto out;
}

2024-01-29 12:42:05

by Jeff Layton

Subject: Re: [PATCH 1/2] netfs: Fix i_dio_count leak on DIO read past i_size

On Mon, 2024-01-29 at 09:49 +0000, David Howells wrote:
> From: Marc Dionne <[email protected]>
>
> If netfs_begin_read gets a NETFS_DIO_READ request that begins
> past i_size, it won't perform any i/o and just return 0. This
> will leak an increment to i_dio_count that is done at the top
> of the function.
>
> This can cause subsequent buffered read requests to block
> indefinitely, waiting for a non existing dio operation to complete.
>
> Add a inode_dio_end() for the NETFS_DIO_READ case, before returning.
>
> Signed-off-by: Marc Dionne <[email protected]>
> Signed-off-by: David Howells <[email protected]>
> cc: Jeff Layton <[email protected]>
> cc: [email protected]
> cc: [email protected]
> cc: [email protected]
> ---
> fs/netfs/io.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/fs/netfs/io.c b/fs/netfs/io.c
> index e8ff1e61ce79..4261ad6c55b6 100644
> --- a/fs/netfs/io.c
> +++ b/fs/netfs/io.c
> @@ -748,6 +748,8 @@ int netfs_begin_read(struct netfs_io_request *rreq, bool sync)
>
> if (!rreq->submitted) {
> netfs_put_request(rreq, false, netfs_rreq_trace_put_no_submit);
> + if (rreq->origin == NETFS_DIO_READ)
> + inode_dio_end(rreq->inode);
> ret = 0;
> goto out;
> }
>
>

Reviewed-by: Jeff Layton <[email protected]>