remove rq_vec

remove rq_vec

[Christoph Hellwig]

Hi all,

this series remove the rq_vec field from the svc_rqst structure and
always uses the bvec array for VFS operations.

It doesn't integrate the bvec arrays used by the socket transport and
those of the VFS layer in nfsd yet, but it is a step toward that.

Diffstat:
 fs/nfsd/nfs3proc.c         |    5 ----
 fs/nfsd/nfs4proc.c         |    7 ------
 fs/nfsd/nfsproc.c          |    7 +-----
 fs/nfsd/vfs.c              |   49 ++++++++++++++++++++++++++++-----------------
 fs/nfsd/vfs.h              |    4 +--
 include/linux/sunrpc/svc.h |    3 --
 net/sunrpc/svc.c           |   40 ------------------------------------
 7 files changed, 37 insertions(+), 78 deletions(-)

[PATCH 1/3] nfsd: call svc_fill_write_vector from nfsd_vfs_write

[Christoph Hellwig]

Creating the kvec is always done so that nfsd_vfs_write can use them.
Move the call there Instead of doing it in the first and second degree
callers, which just makes the code more complicated.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/nfsd/nfs3proc.c |  5 +----
 fs/nfsd/nfs4proc.c |  7 +------
 fs/nfsd/nfsproc.c  |  7 ++-----
 fs/nfsd/vfs.c      | 18 +++++++++++-------
 fs/nfsd/vfs.h      |  4 ++--
 5 files changed, 17 insertions(+), 24 deletions(-)

diff --git a/fs/nfsd/nfs3proc.c b/fs/nfsd/nfs3proc.c
index 372bdcf5e07a..3eecaabd96ce 100644
--- a/fs/nfsd/nfs3proc.c
+++ b/fs/nfsd/nfs3proc.c
@@ -220,7 +220,6 @@ nfsd3_proc_write(struct svc_rqst *rqstp)
 	struct nfsd3_writeargs *argp = rqstp->rq_argp;
 	struct nfsd3_writeres *resp = rqstp->rq_resp;
 	unsigned long cnt = argp->len;
-	unsigned int nvecs;
 
 	dprintk("nfsd: WRITE(3)    %s %d bytes at %Lu%s\n",
 				SVCFH_fmt(&argp->fh),
@@ -235,10 +234,8 @@ nfsd3_proc_write(struct svc_rqst *rqstp)
 
 	fh_copy(&resp->fh, &argp->fh);
 	resp->committed = argp->stable;
-	nvecs = svc_fill_write_vector(rqstp, &argp->payload);
-
 	resp->status = nfsd_write(rqstp, &resp->fh, argp->offset,
-				  rqstp->rq_vec, nvecs, &cnt,
+				  &argp->payload, &cnt,
 				  resp->committed, resp->verf);
 	resp->count = cnt;
 	resp->status = nfsd3_map_status(resp->status);
diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index b397246dae7b..2b814fc4c8cc 100644
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -1211,7 +1211,6 @@ nfsd4_write(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 	struct nfsd_file *nf = NULL;
 	__be32 status = nfs_ok;
 	unsigned long cnt;
-	int nvecs;
 
 	if (write->wr_offset > (u64)OFFSET_MAX ||
 	    write->wr_offset + write->wr_buflen > (u64)OFFSET_MAX)
@@ -1226,12 +1225,8 @@ nfsd4_write(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 		return status;
 
 	write->wr_how_written = write->wr_stable_how;
-
-	nvecs = svc_fill_write_vector(rqstp, &write->wr_payload);
-	WARN_ON_ONCE(nvecs > ARRAY_SIZE(rqstp->rq_vec));
-
 	status = nfsd_vfs_write(rqstp, &cstate->current_fh, nf,
-				write->wr_offset, rqstp->rq_vec, nvecs, &cnt,
+				write->wr_offset, &write->wr_payload, &cnt,
 				write->wr_how_written,
 				(__be32 *)write->wr_verifier.data);
 	nfsd_file_put(nf);
diff --git a/fs/nfsd/nfsproc.c b/fs/nfsd/nfsproc.c
index 6dda081eb24c..b4520b6fd9ee 100644
--- a/fs/nfsd/nfsproc.c
+++ b/fs/nfsd/nfsproc.c
@@ -250,17 +250,14 @@ nfsd_proc_write(struct svc_rqst *rqstp)
 	struct nfsd_writeargs *argp = rqstp->rq_argp;
 	struct nfsd_attrstat *resp = rqstp->rq_resp;
 	unsigned long cnt = argp->len;
-	unsigned int nvecs;
 
 	dprintk("nfsd: WRITE    %s %u bytes at %d\n",
 		SVCFH_fmt(&argp->fh),
 		argp->len, argp->offset);
 
-	nvecs = svc_fill_write_vector(rqstp, &argp->payload);
-
 	resp->status = nfsd_write(rqstp, fh_copy(&resp->fh, &argp->fh),
-				  argp->offset, rqstp->rq_vec, nvecs,
-				  &cnt, NFS_DATA_SYNC, NULL);
+				  argp->offset, &argp->payload, &cnt,
+				  NFS_DATA_SYNC, NULL);
 	if (resp->status == nfs_ok)
 		resp->status = fh_getattr(&resp->fh, &resp->stat);
 	else if (resp->status == nfserr_jukebox)
diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index 9abdc4b75813..da62082d06dc 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -1141,9 +1141,8 @@ static int wait_for_concurrent_writes(struct file *file)
 
 __be32
 nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, struct nfsd_file *nf,
-				loff_t offset, struct kvec *vec, int vlen,
-				unsigned long *cnt, int stable,
-				__be32 *verf)
+		loff_t offset, struct xdr_buf *payload, unsigned long *cnt,
+		int stable, __be32 *verf)
 {
 	struct nfsd_net		*nn = net_generic(SVC_NET(rqstp), nfsd_net_id);
 	struct file		*file = nf->nf_file;
@@ -1158,9 +1157,14 @@ nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, struct nfsd_file *nf,
 	unsigned int		pflags = current->flags;
 	rwf_t			flags = 0;
 	bool			restore_flags = false;
+	unsigned int		nvecs;
 
 	trace_nfsd_write_opened(rqstp, fhp, offset, *cnt);
 
+	nvecs = svc_fill_write_vector(rqstp, payload);
+	if (WARN_ON_ONCE(nvecs > ARRAY_SIZE(rqstp->rq_vec)))
+		return -EIO;
+
 	if (sb->s_export_op)
 		exp_op_flags = sb->s_export_op->flags;
 
@@ -1185,7 +1189,7 @@ nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, struct nfsd_file *nf,
 	if (stable && !fhp->fh_use_wgather)
 		flags |= RWF_SYNC;
 
-	iov_iter_kvec(&iter, ITER_SOURCE, vec, vlen, *cnt);
+	iov_iter_kvec(&iter, ITER_SOURCE, rqstp->rq_vec, nvecs, *cnt);
 	since = READ_ONCE(file->f_wb_err);
 	if (verf)
 		nfsd_copy_write_verifier(verf, nn);
@@ -1290,7 +1294,7 @@ __be32 nfsd_read(struct svc_rqst *rqstp, struct svc_fh *fhp,
  */
 __be32
 nfsd_write(struct svc_rqst *rqstp, struct svc_fh *fhp, loff_t offset,
-	   struct kvec *vec, int vlen, unsigned long *cnt, int stable,
+	   struct xdr_buf *payload, unsigned long *cnt, int stable,
 	   __be32 *verf)
 {
 	struct nfsd_file *nf;
@@ -1302,8 +1306,8 @@ nfsd_write(struct svc_rqst *rqstp, struct svc_fh *fhp, loff_t offset,
 	if (err)
 		goto out;
 
-	err = nfsd_vfs_write(rqstp, fhp, nf, offset, vec,
-			vlen, cnt, stable, verf);
+	err = nfsd_vfs_write(rqstp, fhp, nf, offset, payload, cnt, stable,
+			verf);
 	nfsd_file_put(nf);
 out:
 	trace_nfsd_write_done(rqstp, fhp, offset, *cnt);
diff --git a/fs/nfsd/vfs.h b/fs/nfsd/vfs.h
index f9b09b842856..97c509e0d170 100644
--- a/fs/nfsd/vfs.h
+++ b/fs/nfsd/vfs.h
@@ -129,11 +129,11 @@ __be32		nfsd_read(struct svc_rqst *rqstp, struct svc_fh *fhp,
 				loff_t offset, unsigned long *count,
 				u32 *eof);
 __be32 		nfsd_write(struct svc_rqst *, struct svc_fh *, loff_t,
-				struct kvec *, int, unsigned long *,
+				struct xdr_buf *payload, unsigned long *cnt,
 				int stable, __be32 *verf);
 __be32		nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp,
 				struct nfsd_file *nf, loff_t offset,
-				struct kvec *vec, int vlen, unsigned long *cnt,
+				struct xdr_buf *payload, unsigned long *cnt,
 				int stable, __be32 *verf);
 __be32		nfsd_readlink(struct svc_rqst *, struct svc_fh *,
 				char *, int *);
-- 
2.47.2

[PATCH 2/3] nfsd: use rq_bvec instead of rq_vec in nfsd_vfs_write

[Christoph Hellwig]

There is no benefit in using a kvec vs a bvec for in-kernel writes,
but phasing out the kvec here will allow us to eventually remove that
array.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/nfsd/vfs.c              | 10 +++++++---
 include/linux/sunrpc/svc.h |  2 --
 net/sunrpc/svc.c           | 40 --------------------------------------
 3 files changed, 7 insertions(+), 45 deletions(-)

diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index da62082d06dc..0cc9639fba79 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -1161,8 +1161,12 @@ nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, struct nfsd_file *nf,
 
 	trace_nfsd_write_opened(rqstp, fhp, offset, *cnt);
 
-	nvecs = svc_fill_write_vector(rqstp, payload);
-	if (WARN_ON_ONCE(nvecs > ARRAY_SIZE(rqstp->rq_vec)))
+	if (WARN_ON_ONCE(payload->tail->iov_len))
+		return -EIO;
+
+	nvecs = xdr_buf_to_bvec(rqstp->rq_bvec, ARRAY_SIZE(rqstp->rq_bvec),
+			payload);
+	if (WARN_ON_ONCE(nvecs > ARRAY_SIZE(rqstp->rq_bvec)))
 		return -EIO;
 
 	if (sb->s_export_op)
@@ -1189,7 +1193,7 @@ nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, struct nfsd_file *nf,
 	if (stable && !fhp->fh_use_wgather)
 		flags |= RWF_SYNC;
 
-	iov_iter_kvec(&iter, ITER_SOURCE, rqstp->rq_vec, nvecs, *cnt);
+	iov_iter_bvec(&iter, ITER_SOURCE, rqstp->rq_bvec, nvecs, *cnt);
 	since = READ_ONCE(file->f_wb_err);
 	if (verf)
 		nfsd_copy_write_verifier(verf, nn);
diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h
index 74658cca0f38..c25456738315 100644
--- a/include/linux/sunrpc/svc.h
+++ b/include/linux/sunrpc/svc.h
@@ -452,8 +452,6 @@ const char *	   svc_proc_name(const struct svc_rqst *rqstp);
 int		   svc_encode_result_payload(struct svc_rqst *rqstp,
 					     unsigned int offset,
 					     unsigned int length);
-unsigned int	   svc_fill_write_vector(struct svc_rqst *rqstp,
-					 struct xdr_buf *payload);
 char		  *svc_fill_symlink_pathname(struct svc_rqst *rqstp,
 					     struct kvec *first, void *p,
 					     size_t total);
diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c
index e7f9c295d13c..9fd370d6676c 100644
--- a/net/sunrpc/svc.c
+++ b/net/sunrpc/svc.c
@@ -1713,46 +1713,6 @@ int svc_encode_result_payload(struct svc_rqst *rqstp, unsigned int offset,
 }
 EXPORT_SYMBOL_GPL(svc_encode_result_payload);
 
-/**
- * svc_fill_write_vector - Construct data argument for VFS write call
- * @rqstp: svc_rqst to operate on
- * @payload: xdr_buf containing only the write data payload
- *
- * Fills in rqstp::rq_vec, and returns the number of elements.
- */
-unsigned int svc_fill_write_vector(struct svc_rqst *rqstp,
-				   struct xdr_buf *payload)
-{
-	struct page **pages = payload->pages;
-	struct kvec *first = payload->head;
-	struct kvec *vec = rqstp->rq_vec;
-	size_t total = payload->len;
-	unsigned int i;
-
-	/* Some types of transport can present the write payload
-	 * entirely in rq_arg.pages. In this case, @first is empty.
-	 */
-	i = 0;
-	if (first->iov_len) {
-		vec[i].iov_base = first->iov_base;
-		vec[i].iov_len = min_t(size_t, total, first->iov_len);
-		total -= vec[i].iov_len;
-		++i;
-	}
-
-	while (total) {
-		vec[i].iov_base = page_address(*pages);
-		vec[i].iov_len = min_t(size_t, total, PAGE_SIZE);
-		total -= vec[i].iov_len;
-		++i;
-		++pages;
-	}
-
-	WARN_ON_ONCE(i > ARRAY_SIZE(rqstp->rq_vec));
-	return i;
-}
-EXPORT_SYMBOL_GPL(svc_fill_write_vector);
-
 /**
  * svc_fill_symlink_pathname - Construct pathname argument for VFS symlink call
  * @rqstp: svc_rqst to operate on
-- 
2.47.2

[PATCH 3/3] nfsd: use rq_bvec in nfsd_iter_read

[Christoph Hellwig]

Using a bvec array vs a kvec one slightly simplifies the logic, and allow
to remove the rq_vecs array.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/nfsd/vfs.c              | 27 ++++++++++++++++-----------
 include/linux/sunrpc/svc.h |  1 -
 2 files changed, 16 insertions(+), 12 deletions(-)

diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index 0cc9639fba79..1804aed0739b 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -1078,26 +1078,31 @@ __be32 nfsd_iter_read(struct svc_rqst *rqstp, struct svc_fh *fhp,
 		      struct file *file, loff_t offset, unsigned long *count,
 		      unsigned int base, u32 *eof)
 {
-	unsigned long v, total;
+	unsigned long total = *count;
 	struct iov_iter iter;
 	loff_t ppos = offset;
-	struct page *page;
+	unsigned int v = 0;
 	ssize_t host_err;
 
-	v = 0;
-	total = *count;
+	/*
+	 * Note: if this request is served through the socket transport, rq_bvec
+	 * will be rebuilt again in the transport, including the XDR header and
+	 * trailer.  It would be nice to fully build it in one place, but that
+	 * needs more work.
+	 */
 	while (total) {
-		page = *(rqstp->rq_next_page++);
-		rqstp->rq_vec[v].iov_base = page_address(page) + base;
-		rqstp->rq_vec[v].iov_len = min_t(size_t, total, PAGE_SIZE - base);
-		total -= rqstp->rq_vec[v].iov_len;
-		++v;
+		unsigned int len = min(total, PAGE_SIZE - base);
+		struct page *page = *(rqstp->rq_next_page++);
+
+		bvec_set_page(&rqstp->rq_bvec[v++], page, len, base);
+		if (WARN_ON_ONCE(v > ARRAY_SIZE(rqstp->rq_bvec)))
+			return -EIO;
+		total -= len;
 		base = 0;
 	}
-	WARN_ON_ONCE(v > ARRAY_SIZE(rqstp->rq_vec));
 
 	trace_nfsd_read_vector(rqstp, fhp, offset, *count);
-	iov_iter_kvec(&iter, ITER_DEST, rqstp->rq_vec, v, *count);
+	iov_iter_bvec(&iter, ITER_DEST, rqstp->rq_bvec, v, *count);
 	host_err = vfs_iter_read(file, &iter, &ppos, 0);
 	return nfsd_finish_read(rqstp, fhp, file, offset, count, eof, host_err);
 }
diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h
index c25456738315..a040583a29da 100644
--- a/include/linux/sunrpc/svc.h
+++ b/include/linux/sunrpc/svc.h
@@ -194,7 +194,6 @@ struct svc_rqst {
 	struct page *		*rq_page_end;  /* one past the last page */
 
 	struct folio_batch	rq_fbatch;
-	struct kvec		rq_vec[RPCSVC_MAXPAGES]; /* generally useful.. */
 	struct bio_vec		rq_bvec[RPCSVC_MAXPAGES];
 
 	__be32			rq_xid;		/* transmission id */
-- 
2.47.2

Re: remove rq_vec

[Chuck Lever]

On 5/7/25 7:55 AM, Christoph Hellwig wrote:
> Hi all,
> 
> this series remove the rq_vec field from the svc_rqst structure and
> always uses the bvec array for VFS operations.
> 
> It doesn't integrate the bvec arrays used by the socket transport and
> those of the VFS layer in nfsd yet, but it is a step toward that.
> 
> Diffstat:
>  fs/nfsd/nfs3proc.c         |    5 ----
>  fs/nfsd/nfs4proc.c         |    7 ------
>  fs/nfsd/nfsproc.c          |    7 +-----
>  fs/nfsd/vfs.c              |   49 ++++++++++++++++++++++++++++-----------------
>  fs/nfsd/vfs.h              |    4 +--
>  include/linux/sunrpc/svc.h |    3 --
>  net/sunrpc/svc.c           |   40 ------------------------------------
>  7 files changed, 37 insertions(+), 78 deletions(-)

I already have patches to do this in test.


-- 
Chuck Lever

Re: [PATCH 2/3] nfsd: use rq_bvec instead of rq_vec in nfsd_vfs_write

[kernel test robot]

Hi Christoph,

kernel test robot noticed the following build errors:

[auto build test ERROR on brauner-vfs/vfs.all]
[also build test ERROR on trondmy-nfs/linux-next linus/master v6.15-rc5]
[cannot apply to next-20250508]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Christoph-Hellwig/nfsd-use-rq_bvec-instead-of-rq_vec-in-nfsd_vfs_write/20250507-205615
base:   https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git vfs.all
patch link:    https://lore.kernel.org/r/20250507115617.3995150-3-hch%40lst.de
patch subject: [PATCH 2/3] nfsd: use rq_bvec instead of rq_vec in nfsd_vfs_write
config: m68k-defconfig (https://download.01.org/0day-ci/archive/20250508/202505082324.vojWBNIq-lkp@intel.com/config)
compiler: m68k-linux-gcc (GCC) 14.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250508/202505082324.vojWBNIq-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202505082324.vojWBNIq-lkp@intel.com/

All errors (new ones prefixed by >>, old ones prefixed by <<):

>> ERROR: modpost: "xdr_buf_to_bvec" [fs/nfsd/nfsd.ko] undefined!

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

Re: [PATCH 1/3] nfsd: call svc_fill_write_vector from nfsd_vfs_write

[kernel test robot]

Hi Christoph,

kernel test robot noticed the following build warnings:

[auto build test WARNING on brauner-vfs/vfs.all]
[also build test WARNING on trondmy-nfs/linux-next linus/master v6.15-rc5]
[cannot apply to next-20250508]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Christoph-Hellwig/nfsd-use-rq_bvec-instead-of-rq_vec-in-nfsd_vfs_write/20250507-205615
base:   https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git vfs.all
patch link:    https://lore.kernel.org/r/20250507115617.3995150-2-hch%40lst.de
patch subject: [PATCH 1/3] nfsd: call svc_fill_write_vector from nfsd_vfs_write
config: x86_64-randconfig-121-20250508 (https://download.01.org/0day-ci/archive/20250509/202505090631.R8lqfckA-lkp@intel.com/config)
compiler: clang version 20.1.2 (https://github.com/llvm/llvm-project 58df0ef89dd64126512e4ee27b4ac3fd8ddf6247)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250509/202505090631.R8lqfckA-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202505090631.R8lqfckA-lkp@intel.com/

sparse warnings: (new ones prefixed by >>)
>> fs/nfsd/vfs.c:1167:24: sparse: sparse: incorrect type in return expression (different base types) @@     expected restricted __be32 @@     got int @@
   fs/nfsd/vfs.c:1167:24: sparse:     expected restricted __be32
   fs/nfsd/vfs.c:1167:24: sparse:     got int

vim +1167 fs/nfsd/vfs.c

  1142	
  1143	__be32
  1144	nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, struct nfsd_file *nf,
  1145			loff_t offset, struct xdr_buf *payload, unsigned long *cnt,
  1146			int stable, __be32 *verf)
  1147	{
  1148		struct nfsd_net		*nn = net_generic(SVC_NET(rqstp), nfsd_net_id);
  1149		struct file		*file = nf->nf_file;
  1150		struct super_block	*sb = file_inode(file)->i_sb;
  1151		struct svc_export	*exp;
  1152		struct iov_iter		iter;
  1153		errseq_t		since;
  1154		__be32			nfserr;
  1155		int			host_err;
  1156		loff_t			pos = offset;
  1157		unsigned long		exp_op_flags = 0;
  1158		unsigned int		pflags = current->flags;
  1159		rwf_t			flags = 0;
  1160		bool			restore_flags = false;
  1161		unsigned int		nvecs;
  1162	
  1163		trace_nfsd_write_opened(rqstp, fhp, offset, *cnt);
  1164	
  1165		nvecs = svc_fill_write_vector(rqstp, payload);
  1166		if (WARN_ON_ONCE(nvecs > ARRAY_SIZE(rqstp->rq_vec)))
> 1167			return -EIO;
  1168	
  1169		if (sb->s_export_op)
  1170			exp_op_flags = sb->s_export_op->flags;
  1171	
  1172		if (test_bit(RQ_LOCAL, &rqstp->rq_flags) &&
  1173		    !(exp_op_flags & EXPORT_OP_REMOTE_FS)) {
  1174			/*
  1175			 * We want throttling in balance_dirty_pages()
  1176			 * and shrink_inactive_list() to only consider
  1177			 * the backingdev we are writing to, so that nfs to
  1178			 * localhost doesn't cause nfsd to lock up due to all
  1179			 * the client's dirty pages or its congested queue.
  1180			 */
  1181			current->flags |= PF_LOCAL_THROTTLE;
  1182			restore_flags = true;
  1183		}
  1184	
  1185		exp = fhp->fh_export;
  1186	
  1187		if (!EX_ISSYNC(exp))
  1188			stable = NFS_UNSTABLE;
  1189	
  1190		if (stable && !fhp->fh_use_wgather)
  1191			flags |= RWF_SYNC;
  1192	
  1193		iov_iter_kvec(&iter, ITER_SOURCE, rqstp->rq_vec, nvecs, *cnt);
  1194		since = READ_ONCE(file->f_wb_err);
  1195		if (verf)
  1196			nfsd_copy_write_verifier(verf, nn);
  1197		host_err = vfs_iter_write(file, &iter, &pos, flags);
  1198		if (host_err < 0) {
  1199			commit_reset_write_verifier(nn, rqstp, host_err);
  1200			goto out_nfserr;
  1201		}
  1202		*cnt = host_err;
  1203		nfsd_stats_io_write_add(nn, exp, *cnt);
  1204		fsnotify_modify(file);
  1205		host_err = filemap_check_wb_err(file->f_mapping, since);
  1206		if (host_err < 0)
  1207			goto out_nfserr;
  1208	
  1209		if (stable && fhp->fh_use_wgather) {
  1210			host_err = wait_for_concurrent_writes(file);
  1211			if (host_err < 0)
  1212				commit_reset_write_verifier(nn, rqstp, host_err);
  1213		}
  1214	
  1215	out_nfserr:
  1216		if (host_err >= 0) {
  1217			trace_nfsd_write_io_done(rqstp, fhp, offset, *cnt);
  1218			nfserr = nfs_ok;
  1219		} else {
  1220			trace_nfsd_write_err(rqstp, fhp, offset, host_err);
  1221			nfserr = nfserrno(host_err);
  1222		}
  1223		if (restore_flags)
  1224			current_restore_flags(pflags, PF_LOCAL_THROTTLE);
  1225		return nfserr;
  1226	}
  1227	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki