[PATCH 1/3] NFSv4: Track the number of referring calls in struct cb_process_state

[PATCH 1/3] NFSv4: Track the number of referring calls in struct cb_process_state

[trondmy]

From: Trond Myklebust <trond.myklebust@hammerspace.com>

When the server gives us a set of referring calls, to tell us that the
NFSv4.1 callback needs to be ordered with respect to those calls, then
we may want to make that information available to the operations. In
certain cases, it may allow them to optimise their behaviour due to the
extra knowledge.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
---
 fs/nfs/callback.h      |  5 +++--
 fs/nfs/callback_proc.c | 11 ++++++++---
 2 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/fs/nfs/callback.h b/fs/nfs/callback.h
index ccd4f245cae2..cc1b6620a0c2 100644
--- a/fs/nfs/callback.h
+++ b/fs/nfs/callback.h
@@ -40,11 +40,12 @@ enum nfs4_callback_opnum {
 
 struct nfs4_slot;
 struct cb_process_state {
-	__be32			drc_status;
 	struct nfs_client	*clp;
 	struct nfs4_slot	*slot;
-	u32			minorversion;
 	struct net		*net;
+	u32			minorversion;
+	__be32			drc_status;
+	unsigned int		referring_calls;
 };
 
 struct cb_compound_hdr_arg {
diff --git a/fs/nfs/callback_proc.c b/fs/nfs/callback_proc.c
index 6bed1394d748..ebecd1f6409e 100644
--- a/fs/nfs/callback_proc.c
+++ b/fs/nfs/callback_proc.c
@@ -450,6 +450,7 @@ static int referring_call_exists(struct nfs_client *clp,
 	__acquires(lock)
 {
 	int status = 0;
+	int found = 0;
 	int i, j;
 	struct nfs4_session *session;
 	struct nfs4_slot_table *tbl;
@@ -478,11 +479,12 @@ static int referring_call_exists(struct nfs_client *clp,
 			spin_lock(lock);
 			if (status)
 				goto out;
+			found++;
 		}
 	}
 
 out:
-	return status;
+	return status < 0 ? status : found;
 }
 
 __be32 nfs4_callback_sequence(void *argp, void *resp,
@@ -493,6 +495,7 @@ __be32 nfs4_callback_sequence(void *argp, void *resp,
 	struct nfs4_slot_table *tbl;
 	struct nfs4_slot *slot;
 	struct nfs_client *clp;
+	int ret;
 	int i;
 	__be32 status = htonl(NFS4ERR_BADSESSION);
 
@@ -552,11 +555,13 @@ __be32 nfs4_callback_sequence(void *argp, void *resp,
 	 * related callback was received before the response to the original
 	 * call.
 	 */
-	if (referring_call_exists(clp, args->csa_nrclists, args->csa_rclists,
-				&tbl->slot_tbl_lock) < 0) {
+	ret = referring_call_exists(clp, args->csa_nrclists, args->csa_rclists,
+				    &tbl->slot_tbl_lock);
+	if (ret < 0) {
 		status = htonl(NFS4ERR_DELAY);
 		goto out_unlock;
 	}
+	cps->referring_calls = ret;
 
 	/*
 	 * RFC5661 20.9.3
-- 
2.41.0

[PATCH 2/3] NFSv4.1: if referring calls are complete, trust the stateid argument

[trondmy]

From: Trond Myklebust <trond.myklebust@hammerspace.com>

If the server is recalling a layout, and sends us a list of referring
calls that we can see are complete, then we should just trust that the
stateid argument is correct, even if the sequence id doesn't match the
one we hold.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
---
 fs/nfs/callback_proc.c | 44 +++++++++++++++++++++++-------------------
 1 file changed, 24 insertions(+), 20 deletions(-)

diff --git a/fs/nfs/callback_proc.c b/fs/nfs/callback_proc.c
index ebecd1f6409e..c0d16ed3c3c5 100644
--- a/fs/nfs/callback_proc.c
+++ b/fs/nfs/callback_proc.c
@@ -207,7 +207,8 @@ static struct inode *nfs_layout_find_inode(struct nfs_client *clp,
  * Enforce RFC5661 section 12.5.5.2.1. (Layout Recall and Return Sequencing)
  */
 static u32 pnfs_check_callback_stateid(struct pnfs_layout_hdr *lo,
-					const nfs4_stateid *new)
+					const nfs4_stateid *new,
+					struct cb_process_state *cps)
 {
 	u32 oldseq, newseq;
 
@@ -221,28 +222,29 @@ static u32 pnfs_check_callback_stateid(struct pnfs_layout_hdr *lo,
 
 	newseq = be32_to_cpu(new->seqid);
 	/* Are we already in a layout recall situation? */
-	if (test_bit(NFS_LAYOUT_RETURN_REQUESTED, &lo->plh_flags) &&
-	    lo->plh_return_seq != 0) {
-		if (newseq < lo->plh_return_seq)
-			return NFS4ERR_OLD_STATEID;
-		if (newseq > lo->plh_return_seq)
-			return NFS4ERR_DELAY;
-		goto out;
-	}
+	if (test_bit(NFS_LAYOUT_RETURN, &lo->plh_flags))
+		return NFS4ERR_DELAY;
 
-	/* Check that the stateid matches what we think it should be. */
+	/*
+	 * Check that the stateid matches what we think it should be.
+	 * Note that if the server sent us a list of referring calls,
+	 * and we know that those have completed, then we trust the
+	 * stateid argument is correct.
+	 */
 	oldseq = be32_to_cpu(lo->plh_stateid.seqid);
-	if (newseq > oldseq + 1)
+	if (newseq > oldseq + 1 && !cps->referring_calls)
 		return NFS4ERR_DELAY;
+
 	/* Crazy server! */
 	if (newseq <= oldseq)
 		return NFS4ERR_OLD_STATEID;
-out:
+
 	return NFS_OK;
 }
 
 static u32 initiate_file_draining(struct nfs_client *clp,
-				  struct cb_layoutrecallargs *args)
+				  struct cb_layoutrecallargs *args,
+				  struct cb_process_state *cps)
 {
 	struct inode *ino;
 	struct pnfs_layout_hdr *lo;
@@ -266,7 +268,7 @@ static u32 initiate_file_draining(struct nfs_client *clp,
 		goto out;
 	}
 	pnfs_get_layout_hdr(lo);
-	rv = pnfs_check_callback_stateid(lo, &args->cbl_stateid);
+	rv = pnfs_check_callback_stateid(lo, &args->cbl_stateid, cps);
 	if (rv != NFS_OK)
 		goto unlock;
 
@@ -326,10 +328,11 @@ static u32 initiate_bulk_draining(struct nfs_client *clp,
 }
 
 static u32 do_callback_layoutrecall(struct nfs_client *clp,
-				    struct cb_layoutrecallargs *args)
+				    struct cb_layoutrecallargs *args,
+				    struct cb_process_state *cps)
 {
 	if (args->cbl_recall_type == RETURN_FILE)
-		return initiate_file_draining(clp, args);
+		return initiate_file_draining(clp, args, cps);
 	return initiate_bulk_draining(clp, args);
 }
 
@@ -340,11 +343,12 @@ __be32 nfs4_callback_layoutrecall(void *argp, void *resp,
 	u32 res = NFS4ERR_OP_NOT_IN_SESSION;
 
 	if (cps->clp)
-		res = do_callback_layoutrecall(cps->clp, args);
+		res = do_callback_layoutrecall(cps->clp, args, cps);
 	return cpu_to_be32(res);
 }
 
-static void pnfs_recall_all_layouts(struct nfs_client *clp)
+static void pnfs_recall_all_layouts(struct nfs_client *clp,
+				    struct cb_process_state *cps)
 {
 	struct cb_layoutrecallargs args;
 
@@ -352,7 +356,7 @@ static void pnfs_recall_all_layouts(struct nfs_client *clp)
 	memset(&args, 0, sizeof(args));
 	args.cbl_recall_type = RETURN_ALL;
 	/* FIXME we ignore errors, what should we do? */
-	do_callback_layoutrecall(clp, &args);
+	do_callback_layoutrecall(clp, &args, cps);
 }
 
 __be32 nfs4_callback_devicenotify(void *argp, void *resp,
@@ -622,7 +626,7 @@ __be32 nfs4_callback_recallany(void *argp, void *resp,
 		nfs_expire_unused_delegation_types(cps->clp, flags);
 
 	if (args->craa_type_mask & BIT(RCA4_TYPE_MASK_FILE_LAYOUT))
-		pnfs_recall_all_layouts(cps->clp);
+		pnfs_recall_all_layouts(cps->clp, cps);
 
 	if (args->craa_type_mask & BIT(PNFS_FF_RCA4_TYPE_MASK_READ)) {
 		set_bit(NFS4CLNT_RECALL_ANY_LAYOUT_READ, &cps->clp->cl_state);
-- 
2.41.0

[PATCH 3/3] NFSv4.1/pnfs: Ensure we handle the error NFS4ERR_RETURNCONFLICT

[trondmy]

From: Trond Myklebust <trond.myklebust@hammerspace.com>

Once the client has processed the CB_LAYOUTRECALL, but has not yet
successfully returned the layout, the server is supposed to switch to
returning NFS4ERR_RETURNCONFLICT. This patch ensures that we handle
that return value correctly.

Fixes: 183d9e7b112a ("pnfs: rework LAYOUTGET retry handling")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
---
 fs/nfs/nfs4proc.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index e7e80c67d82b..7e3053339d6a 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -170,6 +170,7 @@ static int nfs4_map_errors(int err)
 	case -NFS4ERR_RESOURCE:
 	case -NFS4ERR_LAYOUTTRYLATER:
 	case -NFS4ERR_RECALLCONFLICT:
+	case -NFS4ERR_RETURNCONFLICT:
 		return -EREMOTEIO;
 	case -NFS4ERR_WRONGSEC:
 	case -NFS4ERR_WRONG_CRED:
@@ -558,6 +559,7 @@ static int nfs4_do_handle_exception(struct nfs_server *server,
 		case -NFS4ERR_GRACE:
 		case -NFS4ERR_LAYOUTTRYLATER:
 		case -NFS4ERR_RECALLCONFLICT:
+		case -NFS4ERR_RETURNCONFLICT:
 			exception->delay = 1;
 			return 0;
 
@@ -9691,6 +9693,7 @@ nfs4_layoutget_handle_exception(struct rpc_task *task,
 		status = -EBUSY;
 		break;
 	case -NFS4ERR_RECALLCONFLICT:
+	case -NFS4ERR_RETURNCONFLICT:
 		status = -ERECALLCONFLICT;
 		break;
 	case -NFS4ERR_DELEG_REVOKED:
-- 
2.41.0