fs/nfsd/blocklayout.c - pub/scm/linux/kernel/git/mkl/linux-can - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (c) 2014-2016 Christoph Hellwig.
  */
 #include <linux/exportfs.h>
 #include <linux/iomap.h>
 #include <linux/slab.h>
 #include <linux/pr.h>

 #include <linux/nfsd/debug.h>

 #include "blocklayoutxdr.h"
 #include "pnfs.h"
 #include "filecache.h"
 #include "vfs.h"

 #define NFSDDBG_FACILITY	NFSDDBG_PNFS


 static __be32
 nfsd4_block_proc_layoutget(struct inode *inode, const struct svc_fh *fhp,
 		struct nfsd4_layoutget *args)
 {
 	struct nfsd4_layout_seg *seg = &args->lg_seg;
 	struct super_block *sb = inode->i_sb;
 	u32 block_size = i_blocksize(inode);
 	struct pnfs_block_extent *bex;
 	struct iomap iomap;
 	u32 device_generation = 0;
 	int error;

 	if (seg->offset & (block_size - 1)) {
 		dprintk("pnfsd: I/O misaligned\n");
 		goto out_layoutunavailable;
 	}

 	/*
 	 * Some clients barf on non-zero block numbers for NONE or INVALID
 	 * layouts, so make sure to zero the whole structure.
 	 */
 	error = -ENOMEM;
 	bex = kzalloc(sizeof(*bex), GFP_KERNEL);
 	if (!bex)
 		goto out_error;
 	args->lg_content = bex;

 	error = sb->s_export_op->map_blocks(inode, seg->offset, seg->length,
 					    &iomap, seg->iomode != IOMODE_READ,
 					    &device_generation);
 	if (error) {
 		if (error == -ENXIO)
 			goto out_layoutunavailable;
 		goto out_error;
 	}

 	if (iomap.length < args->lg_minlength) {
 		dprintk("pnfsd: extent smaller than minlength\n");
 		goto out_layoutunavailable;
 	}

 	switch (iomap.type) {
 	case IOMAP_MAPPED:
 		if (seg->iomode == IOMODE_READ)
 			bex->es = PNFS_BLOCK_READ_DATA;
 		else
 			bex->es = PNFS_BLOCK_READWRITE_DATA;
 		bex->soff = iomap.addr;
 		break;
 	case IOMAP_UNWRITTEN:
 		if (seg->iomode & IOMODE_RW) {
 			/*
 			 * Crack monkey special case from section 2.3.1.
 			 */
 			if (args->lg_minlength == 0) {
 				dprintk("pnfsd: no soup for you!\n");
 				goto out_layoutunavailable;
 			}

 			bex->es = PNFS_BLOCK_INVALID_DATA;
 			bex->soff = iomap.addr;
 			break;
 		}
 		fallthrough;
 	case IOMAP_HOLE:
 		if (seg->iomode == IOMODE_READ) {
 			bex->es = PNFS_BLOCK_NONE_DATA;
 			break;
 		}
 		fallthrough;
 	case IOMAP_DELALLOC:
 	default:
 		WARN(1, "pnfsd: filesystem returned %d extent\n", iomap.type);
 		goto out_layoutunavailable;
 	}

 	error = nfsd4_set_deviceid(&bex->vol_id, fhp, device_generation);
 	if (error)
 		goto out_error;
 	bex->foff = iomap.offset;
 	bex->len = iomap.length;

 	seg->offset = iomap.offset;
 	seg->length = iomap.length;

 	dprintk("GET: 0x%llx:0x%llx %d\n", bex->foff, bex->len, bex->es);
 	return 0;

 out_error:
 	seg->length = 0;
 	return nfserrno(error);
 out_layoutunavailable:
 	seg->length = 0;
 	return nfserr_layoutunavailable;
 }

 static __be32
 nfsd4_block_commit_blocks(struct inode *inode, struct nfsd4_layoutcommit *lcp,
 		struct iomap *iomaps, int nr_iomaps)
 {
 	struct timespec64 mtime = inode_get_mtime(inode);
 	loff_t new_size = lcp->lc_last_wr + 1;
 	struct iattr iattr = { .ia_valid = 0 };
 	int error;

 	if (lcp->lc_mtime.tv_nsec == UTIME_NOW ||
 	    timespec64_compare(&lcp->lc_mtime, &mtime) < 0)
 		lcp->lc_mtime = current_time(inode);
 	iattr.ia_valid |= ATTR_ATIME | ATTR_CTIME | ATTR_MTIME;
 	iattr.ia_atime = iattr.ia_ctime = iattr.ia_mtime = lcp->lc_mtime;

 	if (new_size > i_size_read(inode)) {
 		iattr.ia_valid |= ATTR_SIZE;
 		iattr.ia_size = new_size;
 	}

 	error = inode->i_sb->s_export_op->commit_blocks(inode, iomaps,
 			nr_iomaps, &iattr);
 	kfree(iomaps);
 	return nfserrno(error);
 }

 #ifdef CONFIG_NFSD_BLOCKLAYOUT
 static int
 nfsd4_block_get_device_info_simple(struct super_block *sb,
 		struct nfsd4_getdeviceinfo *gdp)
 {
 	struct pnfs_block_deviceaddr *dev;
 	struct pnfs_block_volume *b;

 	dev = kzalloc(struct_size(dev, volumes, 1), GFP_KERNEL);
 	if (!dev)
 		return -ENOMEM;
 	gdp->gd_device = dev;

 	dev->nr_volumes = 1;
 	b = &dev->volumes[0];

 	b->type = PNFS_BLOCK_VOLUME_SIMPLE;
 	b->simple.sig_len = PNFS_BLOCK_UUID_LEN;
 	return sb->s_export_op->get_uuid(sb, b->simple.sig, &b->simple.sig_len,
 			&b->simple.offset);
 }

 static __be32
 nfsd4_block_proc_getdeviceinfo(struct super_block *sb,
 		struct svc_rqst *rqstp,
 		struct nfs4_client *clp,
 		struct nfsd4_getdeviceinfo *gdp)
 {
 	if (bdev_is_partition(sb->s_bdev))
 		return nfserr_inval;
 	return nfserrno(nfsd4_block_get_device_info_simple(sb, gdp));
 }

 static __be32
 nfsd4_block_proc_layoutcommit(struct inode *inode,
 		struct nfsd4_layoutcommit *lcp)
 {
 	struct iomap *iomaps;
 	int nr_iomaps;
 	__be32 nfserr;

 	nfserr = nfsd4_block_decode_layoutupdate(lcp->lc_up_layout,
 			lcp->lc_up_len, &iomaps, &nr_iomaps,
 			i_blocksize(inode));
 	if (nfserr != nfs_ok)
 		return nfserr;

 	return nfsd4_block_commit_blocks(inode, lcp, iomaps, nr_iomaps);
 }

 const struct nfsd4_layout_ops bl_layout_ops = {
 	/*
 	 * Pretend that we send notification to the client.  This is a blatant
 	 * lie to force recent Linux clients to cache our device IDs.
 	 * We rarely ever change the device ID, so the harm of leaking deviceids
 	 * for a while isn't too bad.  Unfortunately RFC5661 is a complete mess
 	 * in this regard, but I filed errata 4119 for this a while ago, and
 	 * hopefully the Linux client will eventually start caching deviceids
 	 * without this again.
 	 */
 	.notify_types		=
 			NOTIFY_DEVICEID4_DELETE | NOTIFY_DEVICEID4_CHANGE,
 	.proc_getdeviceinfo	= nfsd4_block_proc_getdeviceinfo,
 	.encode_getdeviceinfo	= nfsd4_block_encode_getdeviceinfo,
 	.proc_layoutget		= nfsd4_block_proc_layoutget,
 	.encode_layoutget	= nfsd4_block_encode_layoutget,
 	.proc_layoutcommit	= nfsd4_block_proc_layoutcommit,
 };
 #endif /* CONFIG_NFSD_BLOCKLAYOUT */

 #ifdef CONFIG_NFSD_SCSILAYOUT
 #define NFSD_MDS_PR_KEY		0x0100000000000000ULL

 /*
  * We use the client ID as a unique key for the reservations.
  * This allows us to easily fence a client when recalls fail.
  */
 static u64 nfsd4_scsi_pr_key(struct nfs4_client *clp)
 {
 	return ((u64)clp->cl_clientid.cl_boot << 32) | clp->cl_clientid.cl_id;
 }

 static const u8 designator_types[] = {
 	PS_DESIGNATOR_EUI64,
 	PS_DESIGNATOR_NAA,
 };

 static int
 nfsd4_block_get_unique_id(struct gendisk *disk, struct pnfs_block_volume *b)
 {
 	int ret, i;

 	for (i = 0; i < ARRAY_SIZE(designator_types); i++) {
 		u8 type = designator_types[i];

 		ret = disk->fops->get_unique_id(disk, b->scsi.designator, type);
 		if (ret > 0) {
 			b->scsi.code_set = PS_CODE_SET_BINARY;
 			b->scsi.designator_type = type;
 			b->scsi.designator_len = ret;
 			return 0;
 		}
 	}

 	return -EINVAL;
 }

 static int
 nfsd4_block_get_device_info_scsi(struct super_block *sb,
 		struct nfs4_client *clp,
 		struct nfsd4_getdeviceinfo *gdp)
 {
 	struct pnfs_block_deviceaddr *dev;
 	struct pnfs_block_volume *b;
 	const struct pr_ops *ops;
 	int ret;

 	dev = kzalloc(struct_size(dev, volumes, 1), GFP_KERNEL);
 	if (!dev)
 		return -ENOMEM;
 	gdp->gd_device = dev;

 	dev->nr_volumes = 1;
 	b = &dev->volumes[0];

 	b->type = PNFS_BLOCK_VOLUME_SCSI;
 	b->scsi.pr_key = nfsd4_scsi_pr_key(clp);

 	ret = nfsd4_block_get_unique_id(sb->s_bdev->bd_disk, b);
 	if (ret < 0)
 		goto out_free_dev;

 	ret = -EINVAL;
 	ops = sb->s_bdev->bd_disk->fops->pr_ops;
 	if (!ops) {
 		pr_err("pNFS: device %s does not support PRs.\n",
 			sb->s_id);
 		goto out_free_dev;
 	}

 	ret = ops->pr_register(sb->s_bdev, 0, NFSD_MDS_PR_KEY, true);
 	if (ret) {
 		pr_err("pNFS: failed to register key for device %s.\n",
 			sb->s_id);
 		goto out_free_dev;
 	}

 	ret = ops->pr_reserve(sb->s_bdev, NFSD_MDS_PR_KEY,
 			PR_EXCLUSIVE_ACCESS_REG_ONLY, 0);
 	if (ret) {
 		pr_err("pNFS: failed to reserve device %s.\n",
 			sb->s_id);
 		goto out_free_dev;
 	}

 	return 0;

 out_free_dev:
 	kfree(dev);
 	gdp->gd_device = NULL;
 	return ret;
 }

 static __be32
 nfsd4_scsi_proc_getdeviceinfo(struct super_block *sb,
 		struct svc_rqst *rqstp,
 		struct nfs4_client *clp,
 		struct nfsd4_getdeviceinfo *gdp)
 {
 	if (bdev_is_partition(sb->s_bdev))
 		return nfserr_inval;
 	return nfserrno(nfsd4_block_get_device_info_scsi(sb, clp, gdp));
 }
 static __be32
 nfsd4_scsi_proc_layoutcommit(struct inode *inode,
 		struct nfsd4_layoutcommit *lcp)
 {
 	struct iomap *iomaps;
 	int nr_iomaps;
 	__be32 nfserr;

 	nfserr = nfsd4_scsi_decode_layoutupdate(lcp->lc_up_layout,
 			lcp->lc_up_len, &iomaps, &nr_iomaps,
 			i_blocksize(inode));
 	if (nfserr != nfs_ok)
 		return nfserr;

 	return nfsd4_block_commit_blocks(inode, lcp, iomaps, nr_iomaps);
 }

 static void
 nfsd4_scsi_fence_client(struct nfs4_layout_stateid *ls, struct nfsd_file *file)
 {
 	struct nfs4_client *clp = ls->ls_stid.sc_client;
 	struct block_device *bdev = file->nf_file->f_path.mnt->mnt_sb->s_bdev;

 	bdev->bd_disk->fops->pr_ops->pr_preempt(bdev, NFSD_MDS_PR_KEY,
 			nfsd4_scsi_pr_key(clp), 0, true);
 }

 const struct nfsd4_layout_ops scsi_layout_ops = {
 	/*
 	 * Pretend that we send notification to the client.  This is a blatant
 	 * lie to force recent Linux clients to cache our device IDs.
 	 * We rarely ever change the device ID, so the harm of leaking deviceids
 	 * for a while isn't too bad.  Unfortunately RFC5661 is a complete mess
 	 * in this regard, but I filed errata 4119 for this a while ago, and
 	 * hopefully the Linux client will eventually start caching deviceids
 	 * without this again.
 	 */
 	.notify_types		=
 			NOTIFY_DEVICEID4_DELETE | NOTIFY_DEVICEID4_CHANGE,
 	.proc_getdeviceinfo	= nfsd4_scsi_proc_getdeviceinfo,
 	.encode_getdeviceinfo	= nfsd4_block_encode_getdeviceinfo,
 	.proc_layoutget		= nfsd4_block_proc_layoutget,
 	.encode_layoutget	= nfsd4_block_encode_layoutget,
 	.proc_layoutcommit	= nfsd4_scsi_proc_layoutcommit,
 	.fence_client		= nfsd4_scsi_fence_client,
 };
 #endif /* CONFIG_NFSD_SCSILAYOUT */
	// SPDX-License-Identifier: GPL-2.0
	/*
	* Copyright (c) 2014-2016 Christoph Hellwig.
	*/
	#include <linux/exportfs.h>
	#include <linux/iomap.h>
	#include <linux/slab.h>
	#include <linux/pr.h>

	#include <linux/nfsd/debug.h>

	#include "blocklayoutxdr.h"
	#include "pnfs.h"
	#include "filecache.h"
	#include "vfs.h"

	#define NFSDDBG_FACILITY NFSDDBG_PNFS


	static __be32
	nfsd4_block_proc_layoutget(struct inode inode, const struct svc_fh fhp,
	struct nfsd4_layoutget *args)
	{
	struct nfsd4_layout_seg *seg = &args->lg_seg;
	struct super_block *sb = inode->i_sb;
	u32 block_size = i_blocksize(inode);
	struct pnfs_block_extent *bex;
	struct iomap iomap;
	u32 device_generation = 0;
	int error;

	if (seg->offset & (block_size - 1)) {
	dprintk("pnfsd: I/O misaligned\n");
	goto out_layoutunavailable;
	}

	/*
	* Some clients barf on non-zero block numbers for NONE or INVALID
	* layouts, so make sure to zero the whole structure.
	*/
	error = -ENOMEM;
	bex = kzalloc(sizeof(*bex), GFP_KERNEL);
	if (!bex)
	goto out_error;
	args->lg_content = bex;

	error = sb->s_export_op->map_blocks(inode, seg->offset, seg->length,
	&iomap, seg->iomode != IOMODE_READ,
	&device_generation);
	if (error) {
	if (error == -ENXIO)
	goto out_layoutunavailable;
	goto out_error;
	}

	if (iomap.length < args->lg_minlength) {
	dprintk("pnfsd: extent smaller than minlength\n");
	goto out_layoutunavailable;
	}

	switch (iomap.type) {
	case IOMAP_MAPPED:
	if (seg->iomode == IOMODE_READ)
	bex->es = PNFS_BLOCK_READ_DATA;
	else
	bex->es = PNFS_BLOCK_READWRITE_DATA;
	bex->soff = iomap.addr;
	break;
	case IOMAP_UNWRITTEN:
	if (seg->iomode & IOMODE_RW) {
	/*
	* Crack monkey special case from section 2.3.1.
	*/
	if (args->lg_minlength == 0) {
	dprintk("pnfsd: no soup for you!\n");
	goto out_layoutunavailable;
	}

	bex->es = PNFS_BLOCK_INVALID_DATA;
	bex->soff = iomap.addr;
	break;
	}
	fallthrough;
	case IOMAP_HOLE:
	if (seg->iomode == IOMODE_READ) {
	bex->es = PNFS_BLOCK_NONE_DATA;
	break;
	}
	fallthrough;
	case IOMAP_DELALLOC:
	default:
	WARN(1, "pnfsd: filesystem returned %d extent\n", iomap.type);
	goto out_layoutunavailable;
	}

	error = nfsd4_set_deviceid(&bex->vol_id, fhp, device_generation);
	if (error)
	goto out_error;
	bex->foff = iomap.offset;
	bex->len = iomap.length;

	seg->offset = iomap.offset;
	seg->length = iomap.length;

	dprintk("GET: 0x%llx:0x%llx %d\n", bex->foff, bex->len, bex->es);
	return 0;

	out_error:
	seg->length = 0;
	return nfserrno(error);
	out_layoutunavailable:
	seg->length = 0;
	return nfserr_layoutunavailable;
	}

	static __be32
	nfsd4_block_commit_blocks(struct inode inode, struct nfsd4_layoutcommit lcp,
	struct iomap *iomaps, int nr_iomaps)
	{
	struct timespec64 mtime = inode_get_mtime(inode);
	loff_t new_size = lcp->lc_last_wr + 1;
	struct iattr iattr = { .ia_valid = 0 };
	int error;

	if (lcp->lc_mtime.tv_nsec == UTIME_NOW \|\|
	timespec64_compare(&lcp->lc_mtime, &mtime) < 0)
	lcp->lc_mtime = current_time(inode);
	iattr.ia_valid \|= ATTR_ATIME \| ATTR_CTIME \| ATTR_MTIME;
	iattr.ia_atime = iattr.ia_ctime = iattr.ia_mtime = lcp->lc_mtime;

	if (new_size > i_size_read(inode)) {
	iattr.ia_valid \|= ATTR_SIZE;
	iattr.ia_size = new_size;
	}

	error = inode->i_sb->s_export_op->commit_blocks(inode, iomaps,
	nr_iomaps, &iattr);
	kfree(iomaps);
	return nfserrno(error);
	}

	#ifdef CONFIG_NFSD_BLOCKLAYOUT
	static int
	nfsd4_block_get_device_info_simple(struct super_block *sb,
	struct nfsd4_getdeviceinfo *gdp)
	{
	struct pnfs_block_deviceaddr *dev;
	struct pnfs_block_volume *b;

	dev = kzalloc(struct_size(dev, volumes, 1), GFP_KERNEL);
	if (!dev)
	return -ENOMEM;
	gdp->gd_device = dev;

	dev->nr_volumes = 1;
	b = &dev->volumes[0];

	b->type = PNFS_BLOCK_VOLUME_SIMPLE;
	b->simple.sig_len = PNFS_BLOCK_UUID_LEN;
	return sb->s_export_op->get_uuid(sb, b->simple.sig, &b->simple.sig_len,
	&b->simple.offset);
	}

	static __be32
	nfsd4_block_proc_getdeviceinfo(struct super_block *sb,
	struct svc_rqst *rqstp,
	struct nfs4_client *clp,
	struct nfsd4_getdeviceinfo *gdp)
	{
	if (bdev_is_partition(sb->s_bdev))
	return nfserr_inval;
	return nfserrno(nfsd4_block_get_device_info_simple(sb, gdp));
	}

	static __be32
	nfsd4_block_proc_layoutcommit(struct inode *inode,
	struct nfsd4_layoutcommit *lcp)
	{
	struct iomap *iomaps;
	int nr_iomaps;
	__be32 nfserr;

	nfserr = nfsd4_block_decode_layoutupdate(lcp->lc_up_layout,
	lcp->lc_up_len, &iomaps, &nr_iomaps,
	i_blocksize(inode));
	if (nfserr != nfs_ok)
	return nfserr;

	return nfsd4_block_commit_blocks(inode, lcp, iomaps, nr_iomaps);
	}

	const struct nfsd4_layout_ops bl_layout_ops = {
	/*
	* Pretend that we send notification to the client. This is a blatant
	* lie to force recent Linux clients to cache our device IDs.
	* We rarely ever change the device ID, so the harm of leaking deviceids
	* for a while isn't too bad. Unfortunately RFC5661 is a complete mess
	* in this regard, but I filed errata 4119 for this a while ago, and
	* hopefully the Linux client will eventually start caching deviceids
	* without this again.
	*/
	.notify_types =
	NOTIFY_DEVICEID4_DELETE \| NOTIFY_DEVICEID4_CHANGE,
	.proc_getdeviceinfo = nfsd4_block_proc_getdeviceinfo,
	.encode_getdeviceinfo = nfsd4_block_encode_getdeviceinfo,
	.proc_layoutget = nfsd4_block_proc_layoutget,
	.encode_layoutget = nfsd4_block_encode_layoutget,
	.proc_layoutcommit = nfsd4_block_proc_layoutcommit,
	};
	#endif /* CONFIG_NFSD_BLOCKLAYOUT */

	#ifdef CONFIG_NFSD_SCSILAYOUT
	#define NFSD_MDS_PR_KEY 0x0100000000000000ULL

	/*
	* We use the client ID as a unique key for the reservations.
	* This allows us to easily fence a client when recalls fail.
	*/
	static u64 nfsd4_scsi_pr_key(struct nfs4_client *clp)
	{
	return ((u64)clp->cl_clientid.cl_boot << 32) \| clp->cl_clientid.cl_id;
	}

	static const u8 designator_types[] = {
	PS_DESIGNATOR_EUI64,
	PS_DESIGNATOR_NAA,
	};

	static int
	nfsd4_block_get_unique_id(struct gendisk disk, struct pnfs_block_volume b)
	{
	int ret, i;

	for (i = 0; i < ARRAY_SIZE(designator_types); i++) {
	u8 type = designator_types[i];

	ret = disk->fops->get_unique_id(disk, b->scsi.designator, type);
	if (ret > 0) {
	b->scsi.code_set = PS_CODE_SET_BINARY;
	b->scsi.designator_type = type;
	b->scsi.designator_len = ret;
	return 0;
	}
	}

	return -EINVAL;
	}

	static int
	nfsd4_block_get_device_info_scsi(struct super_block *sb,
	struct nfs4_client *clp,
	struct nfsd4_getdeviceinfo *gdp)
	{
	struct pnfs_block_deviceaddr *dev;
	struct pnfs_block_volume *b;
	const struct pr_ops *ops;
	int ret;

	dev = kzalloc(struct_size(dev, volumes, 1), GFP_KERNEL);
	if (!dev)
	return -ENOMEM;
	gdp->gd_device = dev;

	dev->nr_volumes = 1;
	b = &dev->volumes[0];

	b->type = PNFS_BLOCK_VOLUME_SCSI;
	b->scsi.pr_key = nfsd4_scsi_pr_key(clp);

	ret = nfsd4_block_get_unique_id(sb->s_bdev->bd_disk, b);
	if (ret < 0)
	goto out_free_dev;

	ret = -EINVAL;
	ops = sb->s_bdev->bd_disk->fops->pr_ops;
	if (!ops) {
	pr_err("pNFS: device %s does not support PRs.\n",
	sb->s_id);
	goto out_free_dev;
	}

	ret = ops->pr_register(sb->s_bdev, 0, NFSD_MDS_PR_KEY, true);
	if (ret) {
	pr_err("pNFS: failed to register key for device %s.\n",
	sb->s_id);
	goto out_free_dev;
	}

	ret = ops->pr_reserve(sb->s_bdev, NFSD_MDS_PR_KEY,
	PR_EXCLUSIVE_ACCESS_REG_ONLY, 0);
	if (ret) {
	pr_err("pNFS: failed to reserve device %s.\n",
	sb->s_id);
	goto out_free_dev;
	}

	return 0;

	out_free_dev:
	kfree(dev);
	gdp->gd_device = NULL;
	return ret;
	}

	static __be32
	nfsd4_scsi_proc_getdeviceinfo(struct super_block *sb,
	struct svc_rqst *rqstp,
	struct nfs4_client *clp,
	struct nfsd4_getdeviceinfo *gdp)
	{
	if (bdev_is_partition(sb->s_bdev))
	return nfserr_inval;
	return nfserrno(nfsd4_block_get_device_info_scsi(sb, clp, gdp));
	}
	static __be32
	nfsd4_scsi_proc_layoutcommit(struct inode *inode,
	struct nfsd4_layoutcommit *lcp)
	{
	struct iomap *iomaps;
	int nr_iomaps;
	__be32 nfserr;

	nfserr = nfsd4_scsi_decode_layoutupdate(lcp->lc_up_layout,
	lcp->lc_up_len, &iomaps, &nr_iomaps,
	i_blocksize(inode));
	if (nfserr != nfs_ok)
	return nfserr;

	return nfsd4_block_commit_blocks(inode, lcp, iomaps, nr_iomaps);
	}

	static void
	nfsd4_scsi_fence_client(struct nfs4_layout_stateid ls, struct nfsd_file file)
	{
	struct nfs4_client *clp = ls->ls_stid.sc_client;
	struct block_device *bdev = file->nf_file->f_path.mnt->mnt_sb->s_bdev;

	bdev->bd_disk->fops->pr_ops->pr_preempt(bdev, NFSD_MDS_PR_KEY,
	nfsd4_scsi_pr_key(clp), 0, true);
	}

	const struct nfsd4_layout_ops scsi_layout_ops = {
	/*
	* Pretend that we send notification to the client. This is a blatant
	* lie to force recent Linux clients to cache our device IDs.
	* We rarely ever change the device ID, so the harm of leaking deviceids
	* for a while isn't too bad. Unfortunately RFC5661 is a complete mess
	* in this regard, but I filed errata 4119 for this a while ago, and
	* hopefully the Linux client will eventually start caching deviceids
	* without this again.
	*/
	.notify_types =
	NOTIFY_DEVICEID4_DELETE \| NOTIFY_DEVICEID4_CHANGE,
	.proc_getdeviceinfo = nfsd4_scsi_proc_getdeviceinfo,
	.encode_getdeviceinfo = nfsd4_block_encode_getdeviceinfo,
	.proc_layoutget = nfsd4_block_proc_layoutget,
	.encode_layoutget = nfsd4_block_encode_layoutget,
	.proc_layoutcommit = nfsd4_scsi_proc_layoutcommit,
	.fence_client = nfsd4_scsi_fence_client,
	};
	#endif /* CONFIG_NFSD_SCSILAYOUT */