Merge branch 'for-linus' into for-3.1/core

Conflicts:
	block/blk-throttle.c
	block/cfq-iosched.c

Signed-off-by: Jens Axboe <jaxboe@fusionio.com>

11 files changed, 120 insertions, 60 deletions

diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index 144f2a3c7185..6f4850deb272 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -256,7 +256,8 @@ nfs_fhget(struct super_block *sb, struct nfs_fh *fh, struct nfs_fattr *fattr)
 
 	nfs_attr_check_mountpoint(sb, fattr);
 
-	if ((fattr->valid & NFS_ATTR_FATTR_FILEID) == 0 && (fattr->valid & NFS_ATTR_FATTR_MOUNTPOINT) == 0)
+	if (((fattr->valid & NFS_ATTR_FATTR_FILEID) == 0) &&
+	    !nfs_attr_use_mounted_on_fileid(fattr))
 		goto out_no_inode;
 	if ((fattr->valid & NFS_ATTR_FATTR_TYPE) == 0)
 		goto out_no_inode;
@@ -1294,7 +1295,8 @@ static int nfs_update_inode(struct inode *inode, struct nfs_fattr *fattr)
 		if (new_isize != cur_isize) {
 			/* Do we perhaps have any outstanding writes, or has
 			 * the file grown beyond our last write? */
-			if (nfsi->npages == 0 || new_isize > cur_isize) {
+			if ((nfsi->npages == 0 && !test_bit(NFS_INO_LAYOUTCOMMIT, &nfsi->flags)) ||
+			     new_isize > cur_isize) {
 				i_size_write(inode, new_isize);
 				invalid |= NFS_INO_INVALID_ATTR|NFS_INO_INVALID_DATA;
 			}
diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
index b9056cbe68d6..2a55347a2daa 100644
--- a/fs/nfs/internal.h
+++ b/fs/nfs/internal.h
@@ -45,6 +45,17 @@ static inline void nfs_attr_check_mountpoint(struct super_block *parent, struct
 		fattr->valid |= NFS_ATTR_FATTR_MOUNTPOINT;
 }
 
+static inline int nfs_attr_use_mounted_on_fileid(struct nfs_fattr *fattr)
+{
+	if (((fattr->valid & NFS_ATTR_FATTR_MOUNTED_ON_FILEID) == 0) ||
+	    (((fattr->valid & NFS_ATTR_FATTR_MOUNTPOINT) == 0) &&
+	     ((fattr->valid & NFS_ATTR_FATTR_V4_REFERRAL) == 0)))
+		return 0;
+
+	fattr->fileid = fattr->mounted_on_fileid;
+	return 1;
+}
+
 struct nfs_clone_mount {
 	const struct super_block *sb;
 	const struct dentry *dentry;
diff --git a/fs/nfs/nfs4filelayout.c b/fs/nfs/nfs4filelayout.c
index 426908809c97..0bafcc91c27f 100644
--- a/fs/nfs/nfs4filelayout.c
+++ b/fs/nfs/nfs4filelayout.c
@@ -30,6 +30,7 @@
  */
 
 #include <linux/nfs_fs.h>
+#include <linux/nfs_page.h>
 
 #include "internal.h"
 #include "nfs4filelayout.h"
@@ -552,13 +553,18 @@ filelayout_decode_layout(struct pnfs_layout_hdr *flo,
 		__func__, nfl_util, fl->num_fh, fl->first_stripe_index,
 		fl->pattern_offset);
 
-	if (!fl->num_fh)
+	/* Note that a zero value for num_fh is legal for STRIPE_SPARSE.
+	 * Futher checking is done in filelayout_check_layout */
+	if (fl->num_fh < 0 || fl->num_fh >
+	    max(NFS4_PNFS_MAX_STRIPE_CNT, NFS4_PNFS_MAX_MULTI_CNT))
 		goto out_err;
 
-	fl->fh_array = kzalloc(fl->num_fh * sizeof(struct nfs_fh *),
-			       gfp_flags);
-	if (!fl->fh_array)
-		goto out_err;
+	if (fl->num_fh > 0) {
+		fl->fh_array = kzalloc(fl->num_fh * sizeof(struct nfs_fh *),
+				       gfp_flags);
+		if (!fl->fh_array)
+			goto out_err;
+	}
 
 	for (i = 0; i < fl->num_fh; i++) {
 		/* Do we want to use a mempool here? */
@@ -661,8 +667,9 @@ filelayout_pg_test(struct nfs_pageio_descriptor *pgio, struct nfs_page *prev,
 	u64 p_stripe, r_stripe;
 	u32 stripe_unit;
 
-	if (!pnfs_generic_pg_test(pgio, prev, req))
-		return 0;
+	if (!pnfs_generic_pg_test(pgio, prev, req) ||
+	    !nfs_generic_pg_test(pgio, prev, req))
+		return false;
 
 	if (!pgio->pg_lseg)
 		return 1;
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index d2c4b59c896d..5879b23e0c99 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -2265,12 +2265,14 @@ static int nfs4_proc_get_root(struct nfs_server *server, struct nfs_fh *fhandle,
 	return nfs4_map_errors(status);
 }
 
+static void nfs_fixup_referral_attributes(struct nfs_fattr *fattr);
 /*
  * Get locations and (maybe) other attributes of a referral.
  * Note that we'll actually follow the referral later when
  * we detect fsid mismatch in inode revalidation
  */
-static int nfs4_get_referral(struct inode *dir, const struct qstr *name, struct nfs_fattr *fattr, struct nfs_fh *fhandle)
+static int nfs4_get_referral(struct inode *dir, const struct qstr *name,
+			     struct nfs_fattr *fattr, struct nfs_fh *fhandle)
 {
 	int status = -ENOMEM;
 	struct page *page = NULL;
@@ -2288,15 +2290,16 @@ static int nfs4_get_referral(struct inode *dir, const struct qstr *name, struct
 		goto out;
 	/* Make sure server returned a different fsid for the referral */
 	if (nfs_fsid_equal(&NFS_SERVER(dir)->fsid, &locations->fattr.fsid)) {
-		dprintk("%s: server did not return a different fsid for a referral at %s\n", __func__, name->name);
+		dprintk("%s: server did not return a different fsid for"
+			" a referral at %s\n", __func__, name->name);
 		status = -EIO;
 		goto out;
 	}
+	/* Fixup attributes for the nfs_lookup() call to nfs_fhget() */
+	nfs_fixup_referral_attributes(&locations->fattr);
 
+	/* replace the lookup nfs_fattr with the locations nfs_fattr */
 	memcpy(fattr, &locations->fattr, sizeof(struct nfs_fattr));
-	fattr->valid |= NFS_ATTR_FATTR_V4_REFERRAL;
-	if (!fattr->mode)
-		fattr->mode = S_IFDIR;
 	memset(fhandle, 0, sizeof(struct nfs_fh));
 out:
 	if (page)
@@ -4667,11 +4670,15 @@ static size_t nfs4_xattr_list_nfs4_acl(struct dentry *dentry, char *list,
 	return len;
 }
 
+/*
+ * nfs_fhget will use either the mounted_on_fileid or the fileid
+ */
 static void nfs_fixup_referral_attributes(struct nfs_fattr *fattr)
 {
-	if (!((fattr->valid & NFS_ATTR_FATTR_FILEID) &&
-		(fattr->valid & NFS_ATTR_FATTR_FSID) &&
-		(fattr->valid & NFS_ATTR_FATTR_V4_REFERRAL)))
+	if (!(((fattr->valid & NFS_ATTR_FATTR_MOUNTED_ON_FILEID) ||
+	       (fattr->valid & NFS_ATTR_FATTR_FILEID)) &&
+	      (fattr->valid & NFS_ATTR_FATTR_FSID) &&
+	      (fattr->valid & NFS_ATTR_FATTR_V4_REFERRAL)))
 		return;
 
 	fattr->valid |= NFS_ATTR_FATTR_TYPE | NFS_ATTR_FATTR_MODE |
@@ -4686,7 +4693,6 @@ int nfs4_proc_fs_locations(struct inode *dir, const struct qstr *name,
 	struct nfs_server *server = NFS_SERVER(dir);
 	u32 bitmask[2] = {
 		[0] = FATTR4_WORD0_FSID | FATTR4_WORD0_FS_LOCATIONS,
-		[1] = FATTR4_WORD1_MOUNTED_ON_FILEID,
 	};
 	struct nfs4_fs_locations_arg args = {
 		.dir_fh = NFS_FH(dir),
@@ -4705,11 +4711,18 @@ int nfs4_proc_fs_locations(struct inode *dir, const struct qstr *name,
 	int status;
 
 	dprintk("%s: start\n", __func__);
+
+	/* Ask for the fileid of the absent filesystem if mounted_on_fileid
+	 * is not supported */
+	if (NFS_SERVER(dir)->attr_bitmask[1] & FATTR4_WORD1_MOUNTED_ON_FILEID)
+		bitmask[1] |= FATTR4_WORD1_MOUNTED_ON_FILEID;
+	else
+		bitmask[0] |= FATTR4_WORD0_FILEID;
+
 	nfs_fattr_init(&fs_locations->fattr);
 	fs_locations->server = server;
 	fs_locations->nlocations = 0;
 	status = nfs4_call_sync(server->client, server, &msg, &args.seq_args, &res.seq_res, 0);
-	nfs_fixup_referral_attributes(&fs_locations->fattr);
 	dprintk("%s: returned status = %d\n", __func__, status);
 	return status;
 }
@@ -5098,7 +5111,6 @@ static void nfs4_init_channel_attrs(struct nfs41_create_session_args *args)
 	if (mxresp_sz == 0)
 		mxresp_sz = NFS_MAX_FILE_IO_SIZE;
 	/* Fore channel attributes */
-	args->fc_attrs.headerpadsz = 0;
 	args->fc_attrs.max_rqst_sz = mxrqst_sz;
 	args->fc_attrs.max_resp_sz = mxresp_sz;
 	args->fc_attrs.max_ops = NFS4_MAX_OPS;
@@ -5111,7 +5123,6 @@ static void nfs4_init_channel_attrs(struct nfs41_create_session_args *args)
 		args->fc_attrs.max_ops, args->fc_attrs.max_reqs);
 
 	/* Back channel attributes */
-	args->bc_attrs.headerpadsz = 0;
 	args->bc_attrs.max_rqst_sz = PAGE_SIZE;
 	args->bc_attrs.max_resp_sz = PAGE_SIZE;
 	args->bc_attrs.max_resp_sz_cached = 0;
@@ -5131,8 +5142,6 @@ static int nfs4_verify_fore_channel_attrs(struct nfs41_create_session_args *args
 	struct nfs4_channel_attrs *sent = &args->fc_attrs;
 	struct nfs4_channel_attrs *rcvd = &session->fc_attrs;
 
-	if (rcvd->headerpadsz > sent->headerpadsz)
-		return -EINVAL;
 	if (rcvd->max_resp_sz > sent->max_resp_sz)
 		return -EINVAL;
 	/*
@@ -5697,6 +5706,7 @@ static void nfs4_layoutreturn_done(struct rpc_task *task, void *calldata)
 {
 	struct nfs4_layoutreturn *lrp = calldata;
 	struct nfs_server *server;
+	struct pnfs_layout_hdr *lo = NFS_I(lrp->args.inode)->layout;
 
 	dprintk("--> %s\n", __func__);
 
@@ -5708,16 +5718,15 @@ static void nfs4_layoutreturn_done(struct rpc_task *task, void *calldata)
 		nfs_restart_rpc(task, lrp->clp);
 		return;
 	}
+	spin_lock(&lo->plh_inode->i_lock);
 	if (task->tk_status == 0) {
-		struct pnfs_layout_hdr *lo = NFS_I(lrp->args.inode)->layout;
-
 		if (lrp->res.lrs_present) {
-			spin_lock(&lo->plh_inode->i_lock);
 			pnfs_set_layout_stateid(lo, &lrp->res.stateid, true);
-			spin_unlock(&lo->plh_inode->i_lock);
 		} else
 			BUG_ON(!list_empty(&lo->plh_segs));
 	}
+	lo->plh_block_lgets--;
+	spin_unlock(&lo->plh_inode->i_lock);
 	dprintk("<-- %s\n", __func__);
 }
 
diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c
index d869a5e5464b..6870bc61ceec 100644
--- a/fs/nfs/nfs4xdr.c
+++ b/fs/nfs/nfs4xdr.c
@@ -255,7 +255,7 @@ static int nfs4_stat_to_errno(int);
 #define decode_fs_locations_maxsz \
 				(0)
 #define encode_secinfo_maxsz	(op_encode_hdr_maxsz + nfs4_name_maxsz)
-#define decode_secinfo_maxsz	(op_decode_hdr_maxsz + 4 + (NFS_MAX_SECFLAVORS * (16 + GSS_OID_MAX_LEN)))
+#define decode_secinfo_maxsz	(op_decode_hdr_maxsz + 1 + ((NFS_MAX_SECFLAVORS * (16 + GSS_OID_MAX_LEN)) / 4))
 
 #if defined(CONFIG_NFS_V4_1)
 #define NFS4_MAX_MACHINE_NAME_LEN (64)
@@ -1725,7 +1725,7 @@ static void encode_create_session(struct xdr_stream *xdr,
 	*p++ = cpu_to_be32(args->flags);			/*flags */
 
 	/* Fore Channel */
-	*p++ = cpu_to_be32(args->fc_attrs.headerpadsz);	/* header padding size */
+	*p++ = cpu_to_be32(0);				/* header padding size */
 	*p++ = cpu_to_be32(args->fc_attrs.max_rqst_sz);	/* max req size */
 	*p++ = cpu_to_be32(args->fc_attrs.max_resp_sz);	/* max resp size */
 	*p++ = cpu_to_be32(max_resp_sz_cached);		/* Max resp sz cached */
@@ -1734,7 +1734,7 @@ static void encode_create_session(struct xdr_stream *xdr,
 	*p++ = cpu_to_be32(0);				/* rdmachannel_attrs */
 
 	/* Back Channel */
-	*p++ = cpu_to_be32(args->fc_attrs.headerpadsz);	/* header padding size */
+	*p++ = cpu_to_be32(0);				/* header padding size */
 	*p++ = cpu_to_be32(args->bc_attrs.max_rqst_sz);	/* max req size */
 	*p++ = cpu_to_be32(args->bc_attrs.max_resp_sz);	/* max resp size */
 	*p++ = cpu_to_be32(args->bc_attrs.max_resp_sz_cached);	/* Max resp sz cached */
@@ -3098,7 +3098,7 @@ out_overflow:
 	return -EIO;
 }
 
-static int decode_attr_error(struct xdr_stream *xdr, uint32_t *bitmap)
+static int decode_attr_error(struct xdr_stream *xdr, uint32_t *bitmap, int32_t *res)
 {
 	__be32 *p;
 
@@ -3109,7 +3109,7 @@ static int decode_attr_error(struct xdr_stream *xdr, uint32_t *bitmap)
 		if (unlikely(!p))
 			goto out_overflow;
 		bitmap[0] &= ~FATTR4_WORD0_RDATTR_ERROR;
-		return -be32_to_cpup(p);
+		*res = -be32_to_cpup(p);
 	}
 	return 0;
 out_overflow:
@@ -4070,6 +4070,7 @@ static int decode_getfattr_attrs(struct xdr_stream *xdr, uint32_t *bitmap,
 	int status;
 	umode_t fmode = 0;
 	uint32_t type;
+	int32_t err;
 
 	status = decode_attr_type(xdr, bitmap, &type);
 	if (status < 0)
@@ -4095,13 +4096,12 @@ static int decode_getfattr_attrs(struct xdr_stream *xdr, uint32_t *bitmap,
 		goto xdr_error;
 	fattr->valid |= status;
 
-	status = decode_attr_error(xdr, bitmap);
-	if (status == -NFS4ERR_WRONGSEC) {
-		nfs_fixup_secinfo_attributes(fattr, fh);
-		status = 0;
-	}
+	err = 0;
+	status = decode_attr_error(xdr, bitmap, &err);
 	if (status < 0)
 		goto xdr_error;
+	if (err == -NFS4ERR_WRONGSEC)
+		nfs_fixup_secinfo_attributes(fattr, fh);
 
 	status = decode_attr_filehandle(xdr, bitmap, fh);
 	if (status < 0)
@@ -4997,12 +4997,14 @@ static int decode_chan_attrs(struct xdr_stream *xdr,
 			     struct nfs4_channel_attrs *attrs)
 {
 	__be32 *p;
-	u32 nr_attrs;
+	u32 nr_attrs, val;
 
 	p = xdr_inline_decode(xdr, 28);
 	if (unlikely(!p))
 		goto out_overflow;
-	attrs->headerpadsz = be32_to_cpup(p++);
+	val = be32_to_cpup(p++);	/* headerpadsz */
+	if (val)
+		return -EINVAL;		/* no support for header padding yet */
 	attrs->max_rqst_sz = be32_to_cpup(p++);
 	attrs->max_resp_sz = be32_to_cpup(p++);
 	attrs->max_resp_sz_cached = be32_to_cpup(p++);
diff --git a/fs/nfs/objlayout/objio_osd.c b/fs/nfs/objlayout/objio_osd.c
index 9cf208df1f25..8ff2ea3f10ef 100644
--- a/fs/nfs/objlayout/objio_osd.c
+++ b/fs/nfs/objlayout/objio_osd.c
@@ -108,7 +108,6 @@ _dev_list_add(const struct nfs_server *nfss,
 		de = n;
 	}
 
-	atomic_inc(&de->id_node.ref);
 	return de;
 }
 
@@ -1001,6 +1000,9 @@ static bool objio_pg_test(struct nfs_pageio_descriptor *pgio,
 	if (!pnfs_generic_pg_test(pgio, prev, req))
 		return false;
 
+	if (pgio->pg_lseg == NULL)
+		return true;
+
 	return pgio->pg_count + req->wb_bytes <=
 			OBJIO_LSEG(pgio->pg_lseg)->max_io_size;
 }
diff --git a/fs/nfs/objlayout/objlayout.c b/fs/nfs/objlayout/objlayout.c
index dc3956c0de80..1d06f8e2adea 100644
--- a/fs/nfs/objlayout/objlayout.c
+++ b/fs/nfs/objlayout/objlayout.c
@@ -291,7 +291,7 @@ objlayout_read_done(struct objlayout_io_state *state, ssize_t status, bool sync)
 	struct nfs_read_data *rdata;
 
 	state->status = status;
-	dprintk("%s: Begin status=%ld eof=%d\n", __func__, status, eof);
+	dprintk("%s: Begin status=%zd eof=%d\n", __func__, status, eof);
 	rdata = state->rpcdata;
 	rdata->task.tk_status = status;
 	if (status >= 0) {
diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
index 7913961aff22..009855716286 100644
--- a/fs/nfs/pagelist.c
+++ b/fs/nfs/pagelist.c
@@ -204,7 +204,7 @@ nfs_wait_on_request(struct nfs_page *req)
 			TASK_UNINTERRUPTIBLE);
 }
 
-static bool nfs_generic_pg_test(struct nfs_pageio_descriptor *desc, struct nfs_page *prev, struct nfs_page *req)
+bool nfs_generic_pg_test(struct nfs_pageio_descriptor *desc, struct nfs_page *prev, struct nfs_page *req)
 {
 	/*
 	 * FIXME: ideally we should be able to coalesce all requests
@@ -218,6 +218,7 @@ static bool nfs_generic_pg_test(struct nfs_pageio_descriptor *desc, struct nfs_p
 
 	return desc->pg_count + req->wb_bytes <= desc->pg_bsize;
 }
+EXPORT_SYMBOL_GPL(nfs_generic_pg_test);
 
 /**
  * nfs_pageio_init - initialise a page io descriptor
diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
index 8c1309d852a6..29c0ca7fc347 100644
--- a/fs/nfs/pnfs.c
+++ b/fs/nfs/pnfs.c
@@ -634,14 +634,16 @@ _pnfs_return_layout(struct inode *ino)
 
 	spin_lock(&ino->i_lock);
 	lo = nfsi->layout;
-	if (!lo || !mark_matching_lsegs_invalid(lo, &tmp_list, NULL)) {
+	if (!lo) {
 		spin_unlock(&ino->i_lock);
-		dprintk("%s: no layout segments to return\n", __func__);
-		goto out;
+		dprintk("%s: no layout to return\n", __func__);
+		return status;
 	}
 	stateid = nfsi->layout->plh_stateid;
 	/* Reference matched in nfs4_layoutreturn_release */
 	get_layout_hdr(lo);
+	mark_matching_lsegs_invalid(lo, &tmp_list, NULL);
+	lo->plh_block_lgets++;
 	spin_unlock(&ino->i_lock);
 	pnfs_free_lseg_list(&tmp_list);
 
@@ -650,6 +652,9 @@ _pnfs_return_layout(struct inode *ino)
 	lrp = kzalloc(sizeof(*lrp), GFP_KERNEL);
 	if (unlikely(lrp == NULL)) {
 		status = -ENOMEM;
+		set_bit(NFS_LAYOUT_RW_FAILED, &lo->plh_flags);
+		set_bit(NFS_LAYOUT_RO_FAILED, &lo->plh_flags);
+		put_layout_hdr(lo);
 		goto out;
 	}
 
@@ -887,7 +892,7 @@ pnfs_find_lseg(struct pnfs_layout_hdr *lo,
 			ret = get_lseg(lseg);
 			break;
 		}
-		if (cmp_layout(range, &lseg->pls_range) > 0)
+		if (lseg->pls_range.offset > range->offset)
 			break;
 	}
 
@@ -1059,23 +1064,36 @@ pnfs_generic_pg_test(struct nfs_pageio_descriptor *pgio, struct nfs_page *prev,
 		gfp_flags = GFP_NOFS;
 	}
 
-	if (pgio->pg_count == prev->wb_bytes) {
+	if (pgio->pg_lseg == NULL) {
+		if (pgio->pg_count != prev->wb_bytes)
+			return true;
 		/* This is first coelesce call for a series of nfs_pages */
 		pgio->pg_lseg = pnfs_update_layout(pgio->pg_inode,
 						   prev->wb_context,
-						   req_offset(req),
+						   req_offset(prev),
 						   pgio->pg_count,
 						   access_type,
 						   gfp_flags);
-		return true;
+		if (pgio->pg_lseg == NULL)
+			return true;
 	}
 
-	if (pgio->pg_lseg &&
-	    req_offset(req) > end_offset(pgio->pg_lseg->pls_range.offset,
-					 pgio->pg_lseg->pls_range.length))
-		return false;
-
-	return true;
+	/*
+	 * Test if a nfs_page is fully contained in the pnfs_layout_range.
+	 * Note that this test makes several assumptions:
+	 * - that the previous nfs_page in the struct nfs_pageio_descriptor
+	 *   is known to lie within the range.
+	 *   - that the nfs_page being tested is known to be contiguous with the
+	 *   previous nfs_page.
+	 *   - Layout ranges are page aligned, so we only have to test the
+	 *   start offset of the request.
+	 *
+	 * Please also note that 'end_offset' is actually the offset of the
+	 * first byte that lies outside the pnfs_layout_range. FIXME?
+	 *
+	 */
+	return req_offset(req) < end_offset(pgio->pg_lseg->pls_range.offset,
+					 pgio->pg_lseg->pls_range.length);
 }
 EXPORT_SYMBOL_GPL(pnfs_generic_pg_test);
 
diff --git a/fs/nfs/pnfs.h b/fs/nfs/pnfs.h
index 48d0a8e4d062..96bf4e6f45be 100644
--- a/fs/nfs/pnfs.h
+++ b/fs/nfs/pnfs.h
@@ -186,6 +186,7 @@ int pnfs_ld_read_done(struct nfs_read_data *);
 /* pnfs_dev.c */
 struct nfs4_deviceid_node {
 	struct hlist_node		node;
+	struct hlist_node		tmpnode;
 	const struct pnfs_layoutdriver_type *ld;
 	const struct nfs_client		*nfs_client;
 	struct nfs4_deviceid		deviceid;
diff --git a/fs/nfs/pnfs_dev.c b/fs/nfs/pnfs_dev.c
index c65e133ce9c0..f0f8e1e22f6c 100644
--- a/fs/nfs/pnfs_dev.c
+++ b/fs/nfs/pnfs_dev.c
@@ -174,6 +174,7 @@ nfs4_init_deviceid_node(struct nfs4_deviceid_node *d,
 			const struct nfs4_deviceid *id)
 {
 	INIT_HLIST_NODE(&d->node);
+	INIT_HLIST_NODE(&d->tmpnode);
 	d->ld = ld;
 	d->nfs_client = nfs_client;
 	d->deviceid = *id;
@@ -208,6 +209,7 @@ nfs4_insert_deviceid_node(struct nfs4_deviceid_node *new)
 
 	hlist_add_head_rcu(&new->node, &nfs4_deviceid_cache[hash]);
 	spin_unlock(&nfs4_deviceid_lock);
+	atomic_inc(&new->ref);
 
 	return new;
 }
@@ -238,24 +240,29 @@ static void
 _deviceid_purge_client(const struct nfs_client *clp, long hash)
 {
 	struct nfs4_deviceid_node *d;
-	struct hlist_node *n, *next;
+	struct hlist_node *n;
 	HLIST_HEAD(tmp);
 
+	spin_lock(&nfs4_deviceid_lock);
 	rcu_read_lock();
 	hlist_for_each_entry_rcu(d, n, &nfs4_deviceid_cache[hash], node)
 		if (d->nfs_client == clp && atomic_read(&d->ref)) {
 			hlist_del_init_rcu(&d->node);
-			hlist_add_head(&d->node, &tmp);
+			hlist_add_head(&d->tmpnode, &tmp);
 		}
 	rcu_read_unlock();
+	spin_unlock(&nfs4_deviceid_lock);
 
 	if (hlist_empty(&tmp))
 		return;
 
 	synchronize_rcu();
-	hlist_for_each_entry_safe(d, n, next, &tmp, node)
+	while (!hlist_empty(&tmp)) {
+		d = hlist_entry(tmp.first, struct nfs4_deviceid_node, tmpnode);
+		hlist_del(&d->tmpnode);
 		if (atomic_dec_and_test(&d->ref))
 			d->ld->free_deviceid_node(d);
+	}
 }
 
 void
@@ -263,8 +270,8 @@ nfs4_deviceid_purge_client(const struct nfs_client *clp)
 {
 	long h;
 
-	spin_lock(&nfs4_deviceid_lock);
+	if (!(clp->cl_exchange_flags & EXCHGID4_FLAG_USE_PNFS_MDS))
+		return;
 	for (h = 0; h < NFS4_DEVICE_ID_HASH_SIZE; h++)
 		_deviceid_purge_client(clp, h);
-	spin_unlock(&nfs4_deviceid_lock);
 }