Re: [PATCH 1/6] NFSv4.1: Callback share session between ops

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On Oct 28, 2010, at 3:35 PM, Trond Myklebust wrote:


On Thu, 2010-10-28 at 15:09 -0400, Fred Isaman wrote:

From: Andy Adamson <andros@xxxxxxxxxx>

The NFSv4.1 session found in cb_sequence needs to be shared by other
callback operations in the same cb_compound.
Hold a reference to the session's nfs_client throughout the cb_compound 
processing.
Wait... That isn't holding a reference. This patch ends up just taking a 
pointer.
See comments in line. cb_sequence gets a reference to nfs_client and it's (for nfsv4.1) held until nfs4_callback_compound is done processing the compound. 


What guarantees that the session+nfs_client won't die on you
while you're processing the callback? Do we wait for callbacks to finish 
before closing the session?


I think so. I'll look.

-->Andy



Trond
Move NFS4ERR_RETRY_UNCACHED_REP processing into nfs4_callback_sequence. 

Signed-off-by: Andy Adamson <andros@xxxxxxxxxx>
Signed-off-by: Fred Isaman <iisaman@xxxxxxxxxx>
---
fs/nfs/callback.h      |   24 ++++++--
fs/nfs/callback_proc.c | 138 +++++++++++++++++++++++++++ +-------------------- 
fs/nfs/callback_xdr.c  |   29 +++++-----
3 files changed, 113 insertions(+), 78 deletions(-)

diff --git a/fs/nfs/callback.h b/fs/nfs/callback.h
index 2ce61b8..89fee05 100644
--- a/fs/nfs/callback.h
+++ b/fs/nfs/callback.h
@@ -34,6 +34,11 @@ enum nfs4_callback_opnum {
	OP_CB_ILLEGAL = 10044,
};

+struct cb_process_state {
+	__be32			drc_status;
+	struct nfs4_session	*session;
+};
+
struct cb_compound_hdr_arg {
	unsigned int taglen;
	const char *tag;
@@ -104,7 +109,8 @@ struct cb_sequenceres {
};

extern unsigned nfs4_callback_sequence(struct cb_sequenceargs *args,
-				       struct cb_sequenceres *res);
+				       struct cb_sequenceres *res,
+				       struct cb_process_state *cps);
extern int nfs41_validate_delegation_stateid(struct nfs_delegation *delegation, 
					     const nfs4_stateid *stateid);
@@ -125,14 +131,17 @@ struct cb_recallanyargs {
	uint32_t	craa_type_mask;
};
-extern unsigned nfs4_callback_recallany(struct cb_recallanyargs *args, void *dummy); +extern unsigned nfs4_callback_recallany(struct cb_recallanyargs *args, 
+					void *dummy,
+					struct cb_process_state *cps);

struct cb_recallslotargs {
	struct sockaddr	*crsa_addr;
	uint32_t	crsa_target_max_slots;
};
extern unsigned nfs4_callback_recallslot(struct cb_recallslotargs *args, 
-					  void *dummy);
+					 void *dummy,
+					 struct cb_process_state *cps);

struct cb_layoutrecallargs {
	struct sockaddr		*cbl_addr;
@@ -147,12 +156,15 @@ struct cb_layoutrecallargs {

extern unsigned nfs4_callback_layoutrecall(
	struct cb_layoutrecallargs *args,
-	void *dummy);
+	void *dummy, struct cb_process_state *cps);

#endif /* CONFIG_NFS_V4_1 */
-extern __be32 nfs4_callback_getattr(struct cb_getattrargs *args, struct cb_getattrres *res); -extern __be32 nfs4_callback_recall(struct cb_recallargs *args, void *dummy); 
+extern __be32 nfs4_callback_getattr(struct cb_getattrargs *args,
+				    struct cb_getattrres *res,
+				    struct cb_process_state *cps);
+extern __be32 nfs4_callback_recall(struct cb_recallargs *args, void *dummy, 
+				   struct cb_process_state *cps);

#ifdef CONFIG_NFS_V4
extern int nfs_callback_up(u32 minorversion, struct rpc_xprt *xprt);
diff --git a/fs/nfs/callback_proc.c b/fs/nfs/callback_proc.c
index 6b560ce..84c5a1b 100644
--- a/fs/nfs/callback_proc.c
+++ b/fs/nfs/callback_proc.c
@@ -20,8 +20,10 @@
#ifdef NFS_DEBUG
#define NFSDBG_FACILITY NFSDBG_CALLBACK
#endif
-
-__be32 nfs4_callback_getattr(struct cb_getattrargs *args, struct cb_getattrres *res) 
+
+__be32 nfs4_callback_getattr(struct cb_getattrargs *args,
+			     struct cb_getattrres *res,
+			     struct cb_process_state *cps)
{
	struct nfs_client *clp;
	struct nfs_delegation *delegation;
@@ -30,9 +32,13 @@ __be32 nfs4_callback_getattr(struct cb_getattrargs *args, struct cb_getattrres * 

	res->bitmap[0] = res->bitmap[1] = 0;
	res->status = htonl(NFS4ERR_BADHANDLE);
-	clp = nfs_find_client(args->addr, 4);
-	if (clp == NULL)
-		goto out;
+	if (cps->session) { /* set in cb_sequence */
+		clp = cps->session->clp;
+	} else {
+		clp = nfs_find_client(args->addr, 4);
+		if (clp == NULL)
+			goto out;
+	}

	dprintk("NFS: GETATTR callback request from %s\n",
		rpc_peeraddr2str(clp->cl_rpcclient, RPC_DISPLAY_ADDR));
@@ -60,22 +66,28 @@ out_iput:
	rcu_read_unlock();
	iput(inode);
out_putclient:
-	nfs_put_client(clp);
+	if (!cps->session)
+		nfs_put_client(clp);
out:
dprintk("%s: exit with status = %d\n", __func__, ntohl(res- >status)); 
	return res->status;
}

-__be32 nfs4_callback_recall(struct cb_recallargs *args, void *dummy)
+__be32 nfs4_callback_recall(struct cb_recallargs *args, void *dummy,
+			    struct cb_process_state *cps)
{
	struct nfs_client *clp;
	struct inode *inode;
	__be32 res;
	
	res = htonl(NFS4ERR_BADHANDLE);
-	clp = nfs_find_client(args->addr, 4);
-	if (clp == NULL)
-		goto out;
+	if (cps->session) { /* set in cb_sequence */
+		clp = cps->session->clp;
+	} else {
+		clp = nfs_find_client(args->addr, 4);
+		if (clp == NULL)
+			goto out;
+	}

	dprintk("NFS: RECALL callback request from %s\n",
		rpc_peeraddr2str(clp->cl_rpcclient, RPC_DISPLAY_ADDR));
@@ -99,9 +111,11 @@ __be32 nfs4_callback_recall(struct cb_recallargs *args, void *dummy) 
			}
			iput(inode);
		}
-		clp = nfs_find_client_next(prev);
-		nfs_put_client(prev);
-	} while (clp != NULL);
+		if (!cps->session) {
+			clp = nfs_find_client_next(prev);
+			nfs_put_client(prev);
+		}
+	} while (!cps->session && clp != NULL);
out:
	dprintk("%s: exit with status = %d\n", __func__, ntohl(res));
	return res;
@@ -346,46 +360,40 @@ static int pnfs_recall_all_layouts(struct nfs_client *clp) 
}

__be32 nfs4_callback_layoutrecall(struct cb_layoutrecallargs *args,
-				  void *dummy)
+				  void *dummy, struct cb_process_state *cps)
{
	struct nfs_client *clp;
	struct inode *inode = NULL;
	__be32 res;
	int status;
-	unsigned int num_client = 0;

	dprintk("%s: -->\n", __func__);

	res = cpu_to_be32(NFS4ERR_OP_NOT_IN_SESSION);
-	clp  = nfs_find_client(args->cbl_addr, 4);
-	if (clp == NULL)
+	if (cps->session) /* set in cb_sequence */
+		clp = cps->session->clp;
+	else
		goto out;

-	res = cpu_to_be32(NFS4ERR_NOMATCHING_LAYOUT);
-	do {
-		struct nfs_client *prev = clp;
-		num_client++;
-		/* the callback must come from the MDS personality */
-		if (!(clp->cl_exchange_flags & EXCHGID4_FLAG_USE_PNFS_MDS))
-			goto loop;
-		/* In the _ALL or _FSID case, we need the inode to get
-		 * the nfs_server struct.
-		 */
-		inode = nfs_layoutrecall_find_inode(clp, args);
-		if (!inode)
-			goto loop;
-		status = pnfs_async_return_layout(clp, inode, args);
-		if (status)
-			res = cpu_to_be32(NFS4ERR_DELAY);
-		iput(inode);
-loop:
-		clp = nfs_find_client_next(prev);
-		nfs_put_client(prev);
-	} while (clp != NULL);
+	/* the callback must come from the MDS personality */
+	res = cpu_to_be32(NFS4ERR_NOTSUPP);
+	if (!(clp->cl_exchange_flags & EXCHGID4_FLAG_USE_PNFS_MDS))
+		goto out;

+	res = cpu_to_be32(NFS4ERR_NOMATCHING_LAYOUT);
+	/*
+	 * In the _ALL or _FSID case, we need the inode to get
+	 * the nfs_server struct.
+	 */
+	inode = nfs_layoutrecall_find_inode(clp, args);
+	if (!inode)
+		goto out;
+	status = pnfs_async_return_layout(clp, inode, args);
+	if (status)
+		res = cpu_to_be32(NFS4ERR_DELAY);
+	iput(inode);
out:
-	dprintk("%s: exit with status = %d numclient %u\n",
-		__func__, ntohl(res), num_client);
+	dprintk("%s: exit with status = %d\n", __func__, ntohl(res));
	return res;
}

@@ -552,12 +560,15 @@ out:
}

__be32 nfs4_callback_sequence(struct cb_sequenceargs *args,
-				struct cb_sequenceres *res)
+			      struct cb_sequenceres *res,
+			      struct cb_process_state *cps)
{
	struct nfs_client *clp;
	int i;
	__be32 status;

+	cps->session = NULL;
+
	status = htonl(NFS4ERR_BADSESSION);
clp = find_client_with_session(args->csa_addr, 4, &args- >csa_sessionid); 

find_client_with_session references the nfs_client.


	if (clp == NULL)
@@ -583,21 +594,27 @@ __be32 nfs4_callback_sequence(struct cb_sequenceargs *args, 
	res->csr_slotid = args->csa_slotid;
	res->csr_highestslotid = NFS41_BC_MAX_CALLBACKS - 1;
	res->csr_target_highestslotid = NFS41_BC_MAX_CALLBACKS - 1;
+	cps->session = clp->cl_session; /* caller must put nfs_client */

-out_putclient:
-	nfs_put_client(clp);
out:
	for (i = 0; i < args->csa_nrclists; i++)
		kfree(args->csa_rclists[i].rcl_refcalls);
	kfree(args->csa_rclists);

-	if (status == htonl(NFS4ERR_RETRY_UNCACHED_REP))
+	if (status == htonl(NFS4ERR_RETRY_UNCACHED_REP)) {
		res->csr_status = 0;
-	else
+		cps->drc_status = status;
+		status = 0;
+	} else
		res->csr_status = status;
+
	dprintk("%s: exit with status = %d res->csr_status %d\n", __func__,
		ntohl(status), ntohl(res->csr_status));
	return status;
+
+out_putclient:
+	nfs_put_client(clp);
+	goto out;
}

static inline bool
@@ -624,24 +641,31 @@ validate_bitmap_values(const unsigned long *mask) 
	return false;
}
-__be32 nfs4_callback_recallany(struct cb_recallanyargs *args, void *dummy) +__be32 nfs4_callback_recallany(struct cb_recallanyargs *args, void *dummy, 
+			       struct cb_process_state *cps)
{
	struct nfs_client *clp;
	__be32 status;
	fmode_t flags = 0;

	status = cpu_to_be32(NFS4ERR_OP_NOT_IN_SESSION);
-	clp = nfs_find_client(args->craa_addr, 4);
-	if (clp == NULL)
+	if (cps->session) /* set in cb_sequence */
+		clp = cps->session->clp;
+	else
		goto out;

	dprintk("NFS: RECALL_ANY callback request from %s\n",
		rpc_peeraddr2str(clp->cl_rpcclient, RPC_DISPLAY_ADDR));

+	/* the callback must come from the MDS personality */
+	status = cpu_to_be32(NFS4ERR_NOTSUPP);
+	if (!(clp->cl_exchange_flags & EXCHGID4_FLAG_USE_PNFS_MDS))
+		goto out;
+
	status = cpu_to_be32(NFS4ERR_INVAL);
	if (!validate_bitmap_values((const unsigned long *)
				    &args->craa_type_mask))
-		goto out_put;
+		goto out;

	status = cpu_to_be32(NFS4_OK);
	if (test_bit(RCA4_TYPE_MASK_RDATA_DLG, (const unsigned long *)
@@ -657,23 +681,23 @@ __be32 nfs4_callback_recallany(struct cb_recallanyargs *args, void *dummy) 

	if (flags)
		nfs_expire_all_delegation_types(clp, flags);
-out_put:
-	nfs_put_client(clp);
out:
	dprintk("%s: exit with status = %d\n", __func__, ntohl(status));
	return status;
}

/* Reduce the fore channel's max_slots to the target value */
-__be32 nfs4_callback_recallslot(struct cb_recallslotargs *args, void *dummy) +__be32 nfs4_callback_recallslot(struct cb_recallslotargs *args, void *dummy, 
+				struct cb_process_state *cps)
{
	struct nfs_client *clp;
	struct nfs4_slot_table *fc_tbl;
	__be32 status;

	status = htonl(NFS4ERR_OP_NOT_IN_SESSION);
-	clp = nfs_find_client(args->crsa_addr, 4);
-	if (clp == NULL)
+	if (cps->session) /* set in cb_sequence */
+		clp = cps->session->clp;
+	else
		goto out;

	dprintk("NFS: CB_RECALL_SLOT request from %s target max slots %d\n",
@@ -685,16 +709,14 @@ __be32 nfs4_callback_recallslot(struct cb_recallslotargs *args, void *dummy) 
	status = htonl(NFS4ERR_BAD_HIGH_SLOT);
	if (args->crsa_target_max_slots > fc_tbl->max_slots ||
	    args->crsa_target_max_slots < 1)
-		goto out_putclient;
+		goto out;

	status = htonl(NFS4_OK);
	if (args->crsa_target_max_slots == fc_tbl->max_slots)
-		goto out_putclient;
+		goto out;

	fc_tbl->target_max_slots = args->crsa_target_max_slots;
	nfs41_handle_recall_slot(clp);
-out_putclient:
-	nfs_put_client(clp);	/* balance nfs_find_client */
out:
	dprintk("%s: exit with status = %d\n", __func__, ntohl(status));
	return status;
diff --git a/fs/nfs/callback_xdr.c b/fs/nfs/callback_xdr.c
index 63b17d0..1650ab0 100644
--- a/fs/nfs/callback_xdr.c
+++ b/fs/nfs/callback_xdr.c
@@ -12,6 +12,7 @@
#include <linux/slab.h>
#include "nfs4_fs.h"
#include "callback.h"
+#include "internal.h"

#define CB_OP_TAGLEN_MAXSZ	(512)
#define CB_OP_HDR_RES_MAXSZ	(2 + CB_OP_TAGLEN_MAXSZ)
@@ -34,7 +35,8 @@
/* Internal error code */
#define NFS4ERR_RESOURCE_HDR	11050

-typedef __be32 (*callback_process_op_t)(void *, void *);
+typedef __be32 (*callback_process_op_t)(void *, void *,
+					struct cb_process_state *);
typedef __be32 (*callback_decode_arg_t)(struct svc_rqst *, struct xdr_stream *, void *); typedef __be32 (*callback_encode_res_t)(struct svc_rqst *, struct xdr_stream *, void *);
@@ -676,7 +678,8 @@ preprocess_nfs4_op(unsigned int op_nr, struct callback_op **op) 
static __be32 process_op(uint32_t minorversion, int nop,
		struct svc_rqst *rqstp,
		struct xdr_stream *xdr_in, void *argp,
-		struct xdr_stream *xdr_out, void *resp, int* drc_status)
+		struct xdr_stream *xdr_out, void *resp,
+		struct cb_process_state *cps)
{
	struct callback_op *op = &callback_ops[0];
	unsigned int op_nr;
@@ -699,8 +702,8 @@ static __be32 process_op(uint32_t minorversion, int nop, 
	if (status)
		goto encode_hdr;

-	if (*drc_status) {
-		status = *drc_status;
+	if (cps->drc_status) {
+		status = cps->drc_status;
		goto encode_hdr;
	}
@@ -708,16 +711,10 @@ static __be32 process_op(uint32_t minorversion, int nop, 
	if (maxlen > 0 && maxlen < PAGE_SIZE) {
		status = op->decode_args(rqstp, xdr_in, argp);
		if (likely(status == 0))
-			status = op->process_op(argp, resp);
+			status = op->process_op(argp, resp, cps);
	} else
		status = htonl(NFS4ERR_RESOURCE);

-	/* Only set by OP_CB_SEQUENCE processing */
-	if (status == htonl(NFS4ERR_RETRY_UNCACHED_REP)) {
-		*drc_status = status;
-		status = 0;
-	}
-
encode_hdr:
	res = encode_op_hdr(xdr_out, op_nr, status);
	if (unlikely(res))
@@ -736,8 +733,10 @@ static __be32 nfs4_callback_compound(struct svc_rqst *rqstp, void *argp, void *r 
	struct cb_compound_hdr_arg hdr_arg = { 0 };
	struct cb_compound_hdr_res hdr_res = { NULL };
	struct xdr_stream xdr_in, xdr_out;
-	__be32 *p;
-	__be32 status, drc_status = 0;
+	__be32 *p, status;
+	struct cb_process_state cps = {
+		.drc_status = 0,
+	};
	unsigned int nops = 0;

	dprintk("%s: start\n", __func__);
@@ -758,7 +757,7 @@ static __be32 nfs4_callback_compound(struct svc_rqst *rqstp, void *argp, void *r 

	while (status == 0 && nops != hdr_arg.nops) {
		status = process_op(hdr_arg.minorversion, nops, rqstp,
-				    &xdr_in, argp, &xdr_out, resp, &drc_status);
+				    &xdr_in, argp, &xdr_out, resp, &cps);
		nops++;
	}
@@ -771,6 +770,8 @@ static __be32 nfs4_callback_compound(struct svc_rqst *rqstp, void *argp, void *r 

	*hdr_res.status = status;
	*hdr_res.nops = htonl(nops);
+ if (cps.session) /* matched by cb_sequence find_client_with_session */ 
+		nfs_put_client(cps.session->clp);


this puts the nfs_client.


	dprintk("%s: done, status = %u\n", __func__, ntohl(status));
	return rpc_success;
}




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