This is a note to let you know that I've just added the patch titled
NFSv4: Fix a deadlock between nfs4_open_recover_helper() and delegreturn
to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
nfsv4-fix-a-deadlock-between-nfs4_open_recover_helpe.patch
and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 451eae83ea587138812ad5f6a920318b0c73238b
Author: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
Date: Fri Nov 4 13:20:01 2022 -0400
NFSv4: Fix a deadlock between nfs4_open_recover_helper() and delegreturn
[ Upstream commit 51069e4aef6257b0454057359faed0ab0c9af083 ]
If we're asked to recover open state while a delegation return is
outstanding, then the state manager thread cannot use a cached open, so
if the server returns a delegation, we can end up deadlocked behind the
pending delegreturn.
To avoid this problem, let's just ask the server not to give us a
delegation unless we're explicitly reclaiming one.
Fixes: be36e185bd26 ("NFSv4: nfs4_open_recover_helper() must set share access")
Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 5baf6ed7732d..4771fc16d7d1 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -1822,18 +1822,18 @@ static struct nfs4_opendata *nfs4_open_recoverdata_alloc(struct nfs_open_context
}
static int nfs4_open_recover_helper(struct nfs4_opendata *opendata,
- fmode_t fmode)
+ fmode_t fmode)
{
struct nfs4_state *newstate;
+ struct nfs_server *server = NFS_SB(opendata->dentry->d_sb);
+ int openflags = opendata->o_arg.open_flags;
int ret;
if (!nfs4_mode_match_open_stateid(opendata->state, fmode))
return 0;
- opendata->o_arg.open_flags = 0;
opendata->o_arg.fmode = fmode;
- opendata->o_arg.share_access = nfs4_map_atomic_open_share(
- NFS_SB(opendata->dentry->d_sb),
- fmode, 0);
+ opendata->o_arg.share_access =
+ nfs4_map_atomic_open_share(server, fmode, openflags);
memset(&opendata->o_res, 0, sizeof(opendata->o_res));
memset(&opendata->c_res, 0, sizeof(opendata->c_res));
nfs4_init_opendata_res(opendata);
@@ -2411,10 +2411,15 @@ static int _nfs4_open_expired(struct nfs_open_context *ctx, struct nfs4_state *s
struct nfs4_opendata *opendata;
int ret;
- opendata = nfs4_open_recoverdata_alloc(ctx, state,
- NFS4_OPEN_CLAIM_FH);
+ opendata = nfs4_open_recoverdata_alloc(ctx, state, NFS4_OPEN_CLAIM_FH);
if (IS_ERR(opendata))
return PTR_ERR(opendata);
+ /*
+ * We're not recovering a delegation, so ask for no delegation.
+ * Otherwise the recovery thread could deadlock with an outstanding
+ * delegation return.
+ */
+ opendata->o_arg.open_flags = O_DIRECT;
ret = nfs4_open_recover(opendata, state);
if (ret == -ESTALE)
d_drop(ctx->dentry);
