Hi David,
On Mon, Oct 21, 2024 at 21:38:23 +0100, David Howells wrote:
> Hi Antony,
>
> I think I may have a fix already lurking on my netfs-writeback branch for the
> next merge window. Can you try the attached?
yes. The fix works. I rebooted a few times and no crash.
Tested-by: Antony Antony <antony.antony@xxxxxxxxxxx>
I am running test script in a loop over night.
thanks,
-antony
>
> David
> ---
> Don't revert the I/O iterator before returning from p9_client_read_once().
> netfslib doesn't require the reversion and nor doed 9P directory reading.
>
> Make p9_client_read() use a temporary iterator to call down into
> p9_client_read_once(), and advance that by the amount read.
>
> Reported-by: Antony Antony <antony@xxxxxxxxxxx>
> Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
> cc: Eric Van Hensbergen <ericvh@xxxxxxxxxx>
> cc: Latchesar Ionkov <lucho@xxxxxxxxxx>
> cc: Dominique Martinet <asmadeus@xxxxxxxxxxxxx>
> cc: Christian Schoenebeck <linux_oss@xxxxxxxxxxxxx>
> cc: v9fs@xxxxxxxxxxxxxxx
> cc: netfs@xxxxxxxxxxxxxxx
> cc: linux-fsdevel@xxxxxxxxxxxxxxx
> ---
> net/9p/client.c | 10 +++-------
> 1 file changed, 3 insertions(+), 7 deletions(-)
>
> diff --git a/net/9p/client.c b/net/9p/client.c
> index 5cd94721d974..be59b0a94eaf 100644
> --- a/net/9p/client.c
> +++ b/net/9p/client.c
> @@ -1519,13 +1519,15 @@ p9_client_read(struct p9_fid *fid, u64 offset, struct iov_iter *to, int *err)
> *err = 0;
>
> while (iov_iter_count(to)) {
> + struct iov_iter tmp = *to;
> int count;
>
> - count = p9_client_read_once(fid, offset, to, err);
> + count = p9_client_read_once(fid, offset, &tmp, err);
> if (!count || *err)
> break;
> offset += count;
> total += count;
> + iov_iter_advance(to, count);
> }
> return total;
> }
> @@ -1567,16 +1569,12 @@ p9_client_read_once(struct p9_fid *fid, u64 offset, struct iov_iter *to,
> }
> if (IS_ERR(req)) {
> *err = PTR_ERR(req);
> - if (!non_zc)
> - iov_iter_revert(to, count - iov_iter_count(to));
> return 0;
> }
>
> *err = p9pdu_readf(&req->rc, clnt->proto_version,
> "D", &received, &dataptr);
> if (*err) {
> - if (!non_zc)
> - iov_iter_revert(to, count - iov_iter_count(to));
> trace_9p_protocol_dump(clnt, &req->rc);
> p9_req_put(clnt, req);
> return 0;
> @@ -1596,8 +1594,6 @@ p9_client_read_once(struct p9_fid *fid, u64 offset, struct iov_iter *to,
> p9_req_put(clnt, req);
> return n;
> }
> - } else {
> - iov_iter_revert(to, count - received - iov_iter_count(to));
> }
> p9_req_put(clnt, req);
> return received;
>
