2022-10-31 15:40:53

by Jeff Layton

Subject: [PATCH] nfsd: fix net-namespace logic in __nfsd_file_cache_purge

If the namespace doesn't match the one in "net", then we'll continue,
but that doesn't cause another rhashtable_walk_next call, so it will
loop infinitely.

Fixes: ce502f81ba88 ("NFSD: Convert the filecache to use rhashtable")
Reported-by: Petr Vorel <[email protected]>
Signed-off-by: Jeff Layton <[email protected]>
---
fs/nfsd/filecache.c | 20 +++++++++-----------
1 file changed, 9 insertions(+), 11 deletions(-)

This should probably go to stable too.

diff --git a/fs/nfsd/filecache.c b/fs/nfsd/filecache.c
index eeed4ae5b4ad..f9ea89057ae8 100644
--- a/fs/nfsd/filecache.c
+++ b/fs/nfsd/filecache.c
@@ -908,19 +908,17 @@ __nfsd_file_cache_purge(struct net *net)

nf = rhashtable_walk_next(&iter);
while (!IS_ERR_OR_NULL(nf)) {
- if (net && nf->nf_net != net)
- continue;
- del = nfsd_file_unhash_and_dispose(nf, &dispose);
-
- /*
- * Deadlock detected! Something marked this entry as
- * unhased, but hasn't removed it from the hash list.
- */
- WARN_ON_ONCE(!del);
-
+ if (!net || nf->nf_net == net) {
+ del = nfsd_file_unhash_and_dispose(nf, &dispose);
+
+ /*
+ * Deadlock detected! Something marked this entry as
+ * unhased, but hasn't removed it from the hash list.
+ */
+ WARN_ON_ONCE(!del);
+ }
nf = rhashtable_walk_next(&iter);
}
-
rhashtable_walk_stop(&iter);
} while (nf == ERR_PTR(-EAGAIN));
rhashtable_walk_exit(&iter);
--
2.38.1

2022-10-31 15:43:45

by Chuck Lever III

Subject: Re: [PATCH] nfsd: fix net-namespace logic in __nfsd_file_cache_purge

> On Oct 31, 2022, at 11:35 AM, Jeff Layton <[email protected]> wrote:
>
> If the namespace doesn't match the one in "net", then we'll continue,
> but that doesn't cause another rhashtable_walk_next call, so it will
> loop infinitely.
>
> Fixes: ce502f81ba88 ("NFSD: Convert the filecache to use rhashtable")
> Reported-by: Petr Vorel <[email protected]>
> Signed-off-by: Jeff Layton <[email protected]>
> ---
> fs/nfsd/filecache.c | 20 +++++++++-----------
> 1 file changed, 9 insertions(+), 11 deletions(-)
>
> This should probably go to stable too.

I tried to apply this to for-rc, but the WARN_ON_ONCE logic
has already been removed there. Can you rebase and resend?


> diff --git a/fs/nfsd/filecache.c b/fs/nfsd/filecache.c
> index eeed4ae5b4ad..f9ea89057ae8 100644
> --- a/fs/nfsd/filecache.c
> +++ b/fs/nfsd/filecache.c
> @@ -908,19 +908,17 @@ __nfsd_file_cache_purge(struct net *net)
>
> nf = rhashtable_walk_next(&iter);
> while (!IS_ERR_OR_NULL(nf)) {
> - if (net && nf->nf_net != net)
> - continue;
> - del = nfsd_file_unhash_and_dispose(nf, &dispose);
> -
> - /*
> - * Deadlock detected! Something marked this entry as
> - * unhased, but hasn't removed it from the hash list.
> - */
> - WARN_ON_ONCE(!del);
> -
> + if (!net || nf->nf_net == net) {
> + del = nfsd_file_unhash_and_dispose(nf, &dispose);
> +
> + /*
> + * Deadlock detected! Something marked this entry as
> + * unhased, but hasn't removed it from the hash list.
> + */
> + WARN_ON_ONCE(!del);
> + }
> nf = rhashtable_walk_next(&iter);
> }
> -
> rhashtable_walk_stop(&iter);
> } while (nf == ERR_PTR(-EAGAIN));
> rhashtable_walk_exit(&iter);
> --
> 2.38.1
>

--
Chuck Lever