Re: [PATCH RFC v21 2/7] NFSD: add support for share reservation conflict to courteous server

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On 4/25/22 6:15 AM, Chuck Lever III wrote:

On Apr 23, 2022, at 2:44 PM, Dai Ngo <dai.ngo@xxxxxxxxxx> wrote:

This patch allows expired client with open state to be in COURTESY
state. Share/access conflict with COURTESY client is resolved by
setting COURTESY client to EXPIRABLE state, schedule laundromat
to run and returning nfserr_jukebox to the request client.

Signed-off-by: Dai Ngo <dai.ngo@xxxxxxxxxx>
---
fs/nfsd/nfs4state.c | 111 +++++++++++++++++++++++++++++++++++++++++++++++++---
1 file changed, 105 insertions(+), 6 deletions(-)

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index fea5e24e7d94..b08c132648b9 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -700,6 +700,57 @@ run_laundromat(struct nfsd_net *nn, bool wait)
		flush_workqueue(laundry_wq);
}

+/*
+ * Check if courtesy clients have conflicting access and resolve it if possible
+ *
+ * access:  is op_share_access if share_access is true.
+ *	    Check if access mode, op_share_access, would conflict with
+ *	    the current deny mode of the file 'fp'.
+ * access:  is op_share_deny if share_access is false.
+ *	    Check if the deny mode, op_share_deny, would conflict with
+ *	    current access of the file 'fp'.
+ * stp:     skip checking this entry.
+ * new_stp: normal open, not open upgrade.
+ *
+ * Function returns:
+ *	false - access/deny mode conflict with normal client.
+ *	true  - no conflict or conflict with courtesy client(s) is resolved.
+ */
+static bool
+nfs4_resolve_deny_conflicts_locked(struct nfs4_file *fp, bool new_stp,
+		struct nfs4_ol_stateid *stp, u32 access, bool share_access)
+{
+	struct nfs4_ol_stateid *st;
+	bool conflict = true;
+	unsigned char bmap;
+	struct nfsd_net *nn;
+	struct nfs4_client *clp;
+
+	lockdep_assert_held(&fp->fi_lock);
+	list_for_each_entry(st, &fp->fi_stateids, st_perfile) {
+		/* ignore lock stateid */
+		if (st->st_openstp)
+			continue;
+		if (st == stp && new_stp)
+			continue;
+		/* check file access against deny mode or vice versa */
+		bmap = share_access ? st->st_deny_bmap : st->st_access_bmap;
+		if (!(access & bmap_to_share_mode(bmap)))
+			continue;
+		clp = st->st_stid.sc_client;
+		if (try_to_expire_client(clp))
+			continue;
+		conflict = false;
+		break;
+	}
+	if (conflict) {
+		clp = stp->st_stid.sc_client;
+		nn = net_generic(clp->net, nfsd_net_id);
+		run_laundromat(nn, false);
+	}
+	return conflict;
+}
+
static void
__nfs4_file_get_access(struct nfs4_file *fp, u32 access)
{
@@ -4995,13 +5046,14 @@ nfsd4_truncate(struct svc_rqst *rqstp, struct svc_fh *fh,

static __be32 nfs4_get_vfs_file(struct svc_rqst *rqstp, struct nfs4_file *fp,
		struct svc_fh *cur_fh, struct nfs4_ol_stateid *stp,
-		struct nfsd4_open *open)
+		struct nfsd4_open *open, bool new_stp)
{
	struct nfsd_file *nf = NULL;
	__be32 status;
	int oflag = nfs4_access_to_omode(open->op_share_access);
	int access = nfs4_access_to_access(open->op_share_access);
	unsigned char old_access_bmap, old_deny_bmap;
+	struct nfs4_client *clp;

	spin_lock(&fp->fi_lock);

@@ -5011,6 +5063,14 @@ static __be32 nfs4_get_vfs_file(struct svc_rqst *rqstp, struct nfs4_file *fp,
	 */
	status = nfs4_file_check_deny(fp, open->op_share_deny);
	if (status != nfs_ok) {
+		if (status != nfserr_share_denied) {
+			spin_unlock(&fp->fi_lock);
+			goto out;
+		}
+		clp = stp->st_stid.sc_client;
@clp is set here, but the value is never used in this function,
even in later patches. Possibly left over from the previous
revision of this series?

Thanks Chuck, will fix in v22.
Kernel test robot also reported the problem.

-Dai



+		if (nfs4_resolve_deny_conflicts_locked(fp, new_stp,
+				stp, open->op_share_deny, false))
+			status = nfserr_jukebox;
		spin_unlock(&fp->fi_lock);
		goto out;
	}
@@ -5018,6 +5078,14 @@ static __be32 nfs4_get_vfs_file(struct svc_rqst *rqstp, struct nfs4_file *fp,
	/* set access to the file */
	status = nfs4_file_get_access(fp, open->op_share_access);
	if (status != nfs_ok) {
+		if (status != nfserr_share_denied) {
+			spin_unlock(&fp->fi_lock);
+			goto out;
+		}
+		clp = stp->st_stid.sc_client;
Ditto.


+		if (nfs4_resolve_deny_conflicts_locked(fp, new_stp,
+				stp, open->op_share_access, true))
+			status = nfserr_jukebox;
		spin_unlock(&fp->fi_lock);
		goto out;
	}
@@ -5064,21 +5132,29 @@ static __be32 nfs4_get_vfs_file(struct svc_rqst *rqstp, struct nfs4_file *fp,
}

static __be32
-nfs4_upgrade_open(struct svc_rqst *rqstp, struct nfs4_file *fp, struct svc_fh *cur_fh, struct nfs4_ol_stateid *stp, struct nfsd4_open *open)
+nfs4_upgrade_open(struct svc_rqst *rqstp, struct nfs4_file *fp,
+		struct svc_fh *cur_fh, struct nfs4_ol_stateid *stp,
+		struct nfsd4_open *open)
{
	__be32 status;
	unsigned char old_deny_bmap = stp->st_deny_bmap;

	if (!test_access(open->op_share_access, stp))
-		return nfs4_get_vfs_file(rqstp, fp, cur_fh, stp, open);
+		return nfs4_get_vfs_file(rqstp, fp, cur_fh, stp, open, false);

	/* test and set deny mode */
	spin_lock(&fp->fi_lock);
	status = nfs4_file_check_deny(fp, open->op_share_deny);
	if (status == nfs_ok) {
-		set_deny(open->op_share_deny, stp);
-		fp->fi_share_deny |=
+		if (status != nfserr_share_denied) {
+			set_deny(open->op_share_deny, stp);
+			fp->fi_share_deny |=
				(open->op_share_deny & NFS4_SHARE_DENY_BOTH);
+		} else {
+			if (nfs4_resolve_deny_conflicts_locked(fp, false,
+					stp, open->op_share_deny, false))
+				status = nfserr_jukebox;
+		}
	}
	spin_unlock(&fp->fi_lock);

@@ -5419,7 +5495,7 @@ nfsd4_process_open2(struct svc_rqst *rqstp, struct svc_fh *current_fh, struct nf
			goto out;
		}
	} else {
-		status = nfs4_get_vfs_file(rqstp, fp, current_fh, stp, open);
+		status = nfs4_get_vfs_file(rqstp, fp, current_fh, stp, open, true);
		if (status) {
			stp->st_stid.sc_type = NFS4_CLOSED_STID;
			release_open_stateid(stp);
@@ -5653,12 +5729,35 @@ static void nfsd4_ssc_expire_umount(struct nfsd_net *nn)
}
#endif

+static bool
+nfs4_has_any_locks(struct nfs4_client *clp)
+{
+	int i;
+	struct nfs4_stateowner *so;
+
+	spin_lock(&clp->cl_lock);
+	for (i = 0; i < OWNER_HASH_SIZE; i++) {
+		list_for_each_entry(so, &clp->cl_ownerstr_hashtbl[i],
+				so_strhash) {
+			if (so->so_is_open_owner)
+				continue;
+			spin_unlock(&clp->cl_lock);
+			return true;
+		}
+	}
+	spin_unlock(&clp->cl_lock);
+	return false;
+}
+
/*
  * place holder for now, no check for lock blockers yet
  */
static bool
nfs4_anylock_blockers(struct nfs4_client *clp)
{
+	/* not allow locks yet */
+	if (nfs4_has_any_locks(clp))
+		return true;
	/*
	 * don't want to check for delegation conflict here since
	 * we need the state_lock for it. The laundromat willexpire
--
2.9.5

--
Chuck Lever






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