cleanup block-style layouts exports v2

cleanup block-style layouts exports v2

[Christoph Hellwig]

Hi all,

this series cleanups the exportfs support for block-style layouts that
provide direct block device access.  This is preparation for supporting
exportfs of more than a single device per file system.

Changes since v1:
 - consity struct exportfs_block_ops
 - fix spelling

Changes since the multi-device export series:
 - check for NULL bops in nfsd4_setup_layout_type
 - clearly document why we are ignoring loca_time_modify

Diffstat:
 MAINTAINERS                    |    2 
 fs/nfsd/blocklayout.c          |   37 +++++++----------
 fs/nfsd/export.c               |    3 -
 fs/nfsd/nfs4layouts.c          |   29 +++----------
 fs/xfs/xfs_export.c            |    4 -
 fs/xfs/xfs_pnfs.c              |   44 ++++++++++++++------
 fs/xfs/xfs_pnfs.h              |   11 ++---
 include/linux/exportfs.h       |   25 +++--------
 include/linux/exportfs_block.h |   88 +++++++++++++++++++++++++++++++++++++++++
 9 files changed, 162 insertions(+), 81 deletions(-)

[PATCH 1/4] nfsd/blocklayout: always ignore loca_time_modify

[Christoph Hellwig]

RFC 8881 Section 18.42 makes it clear that the client provided timestamp
is a "may" condition, and clients that want to force a specific timestamp
should send a separate SETATTR in the compound.

Since commit b82f92d5dd1a ("fs: have setattr_copy handle multigrain
timestamps appropriately") the ia_mtime value is ignored by file
systems using multi-grain timestamps like XFS, which is the only
file system supporting blocklayout exports right now, so make that
explicit in NFSD as well.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
---
 fs/nfsd/blocklayout.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/fs/nfsd/blocklayout.c b/fs/nfsd/blocklayout.c
index a7cfba29990e..5ee5735b39bb 100644
--- a/fs/nfsd/blocklayout.c
+++ b/fs/nfsd/blocklayout.c
@@ -179,15 +179,20 @@ 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);
 	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);
+	/*
+	 * This ignores the client provided mtime in loca_time_modify, as a
+	 * fully client specified mtime doesn't really fit into the Linux
+	 * multi-grain timestamp architecture.
+	 *
+	 * RFC 8881 Section 18.42 makes it clear that the client provided
+	 * timestamp is a "may" condition, and clients that want to force a
+	 * specific timestamp should send a separate SETATTR in the compound.
+	 */
 	iattr.ia_valid |= ATTR_ATIME | ATTR_CTIME | ATTR_MTIME;
-	iattr.ia_atime = iattr.ia_ctime = iattr.ia_mtime = lcp->lc_mtime;
+	iattr.ia_atime = iattr.ia_ctime = iattr.ia_mtime = current_time(inode);
 
 	if (lcp->lc_size_chg) {
 		iattr.ia_valid |= ATTR_SIZE;
-- 
2.47.3

[PATCH 2/4] exportfs: split out the ops for layout-based block device access

[Christoph Hellwig]

The support to grant layouts for direct block device access works
at a very different layer than the rest of exports.  Split the methods
for it into a separate struct, and move that into a separate header
to better split things out.  The pointer to the new operation vector
is kept in export_operations to avoid bloating the super_block.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
---
 MAINTAINERS                    |  2 +-
 fs/nfsd/blocklayout.c          | 14 ++++++------
 fs/nfsd/nfs4layouts.c          |  9 ++++----
 fs/xfs/xfs_export.c            |  4 +---
 fs/xfs/xfs_pnfs.c              | 12 ++++++++---
 fs/xfs/xfs_pnfs.h              | 11 +++++-----
 include/linux/exportfs.h       | 25 +++++++---------------
 include/linux/exportfs_block.h | 39 ++++++++++++++++++++++++++++++++++
 8 files changed, 74 insertions(+), 42 deletions(-)
 create mode 100644 include/linux/exportfs_block.h

diff --git a/MAINTAINERS b/MAINTAINERS
index c3fe46d7c4bc..b531b87a007e 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -9856,7 +9856,7 @@ S:	Supported
 F:	Documentation/filesystems/nfs/exporting.rst
 F:	fs/exportfs/
 F:	fs/fhandle.c
-F:	include/linux/exportfs.h
+F:	include/linux/exportfs*.h
 
 FILESYSTEMS [IDMAPPED MOUNTS]
 M:	Christian Brauner <brauner@kernel.org>
diff --git a/fs/nfsd/blocklayout.c b/fs/nfsd/blocklayout.c
index 5ee5735b39bb..3cc3b47361e2 100644
--- a/fs/nfsd/blocklayout.c
+++ b/fs/nfsd/blocklayout.c
@@ -2,7 +2,7 @@
 /*
  * Copyright (c) 2014-2016 Christoph Hellwig.
  */
-#include <linux/exportfs.h>
+#include <linux/exportfs_block.h>
 #include <linux/iomap.h>
 #include <linux/slab.h>
 #include <linux/pr.h>
@@ -32,8 +32,8 @@ nfsd4_block_map_extent(struct inode *inode, const struct svc_fh *fhp,
 	u32 device_generation = 0;
 	int error;
 
-	error = sb->s_export_op->map_blocks(inode, offset, length, &iomap,
-			iomode != IOMODE_READ, &device_generation);
+	error = sb->s_export_op->block_ops->map_blocks(inode, offset, length,
+			&iomap, iomode != IOMODE_READ, &device_generation);
 	if (error) {
 		if (error == -ENXIO)
 			return nfserr_layoutunavailable;
@@ -199,8 +199,8 @@ nfsd4_block_commit_blocks(struct inode *inode, struct nfsd4_layoutcommit *lcp,
 		iattr.ia_size = lcp->lc_newsize;
 	}
 
-	error = inode->i_sb->s_export_op->commit_blocks(inode, iomaps,
-			nr_iomaps, &iattr);
+	error = inode->i_sb->s_export_op->block_ops->commit_blocks(inode,
+			iomaps, nr_iomaps, &iattr);
 	kfree(iomaps);
 	return nfserrno(error);
 }
@@ -223,8 +223,8 @@ nfsd4_block_get_device_info_simple(struct super_block *sb,
 
 	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);
+	return sb->s_export_op->block_ops->get_uuid(sb, b->simple.sig,
+			&b->simple.sig_len, &b->simple.offset);
 }
 
 static __be32
diff --git a/fs/nfsd/nfs4layouts.c b/fs/nfsd/nfs4layouts.c
index ad7af8cfcf1f..6c1ff21b83a2 100644
--- a/fs/nfsd/nfs4layouts.c
+++ b/fs/nfsd/nfs4layouts.c
@@ -3,6 +3,7 @@
  * Copyright (c) 2014 Christoph Hellwig.
  */
 #include <linux/blkdev.h>
+#include <linux/exportfs_block.h>
 #include <linux/kmod.h>
 #include <linux/file.h>
 #include <linux/jhash.h>
@@ -127,6 +128,7 @@ void nfsd4_setup_layout_type(struct svc_export *exp)
 {
 #if defined(CONFIG_NFSD_BLOCKLAYOUT) || defined(CONFIG_NFSD_SCSILAYOUT)
 	struct super_block *sb = exp->ex_path.mnt->mnt_sb;
+	const struct exportfs_block_ops *bops = sb->s_export_op->block_ops;
 #endif
 
 	if (!(exp->ex_flags & NFSEXP_PNFS))
@@ -136,14 +138,11 @@ void nfsd4_setup_layout_type(struct svc_export *exp)
 	exp->ex_layout_types |= 1 << LAYOUT_FLEX_FILES;
 #endif
 #ifdef CONFIG_NFSD_BLOCKLAYOUT
-	if (sb->s_export_op->get_uuid &&
-	    sb->s_export_op->map_blocks &&
-	    sb->s_export_op->commit_blocks)
+	if (bops && bops->get_uuid && bops->map_blocks && bops->commit_blocks)
 		exp->ex_layout_types |= 1 << LAYOUT_BLOCK_VOLUME;
 #endif
 #ifdef CONFIG_NFSD_SCSILAYOUT
-	if (sb->s_export_op->map_blocks &&
-	    sb->s_export_op->commit_blocks &&
+	if (bops && bops->map_blocks && bops->commit_blocks &&
 	    sb->s_bdev &&
 	    sb->s_bdev->bd_disk->fops->pr_ops &&
 	    sb->s_bdev->bd_disk->fops->get_unique_id)
diff --git a/fs/xfs/xfs_export.c b/fs/xfs/xfs_export.c
index e3e3c3c89840..9b2ad3786b19 100644
--- a/fs/xfs/xfs_export.c
+++ b/fs/xfs/xfs_export.c
@@ -244,8 +244,6 @@ const struct export_operations xfs_export_operations = {
 	.get_parent		= xfs_fs_get_parent,
 	.commit_metadata	= xfs_fs_nfs_commit_metadata,
 #ifdef CONFIG_EXPORTFS_BLOCK_OPS
-	.get_uuid		= xfs_fs_get_uuid,
-	.map_blocks		= xfs_fs_map_blocks,
-	.commit_blocks		= xfs_fs_commit_blocks,
+	.block_ops		= &xfs_export_block_ops,
 #endif
 };
diff --git a/fs/xfs/xfs_pnfs.c b/fs/xfs/xfs_pnfs.c
index 221e55887a2a..12e083f1b9ba 100644
--- a/fs/xfs/xfs_pnfs.c
+++ b/fs/xfs/xfs_pnfs.c
@@ -49,7 +49,7 @@ xfs_break_leased_layouts(
  * Get a unique ID including its location so that the client can identify
  * the exported device.
  */
-int
+static int
 xfs_fs_get_uuid(
 	struct super_block	*sb,
 	u8			*buf,
@@ -104,7 +104,7 @@ xfs_fs_map_update_inode(
 /*
  * Get a layout for the pNFS client.
  */
-int
+static int
 xfs_fs_map_blocks(
 	struct inode		*inode,
 	loff_t			offset,
@@ -252,7 +252,7 @@ xfs_pnfs_validate_isize(
  * to manually flush the cache here similar to what the fsync code path does
  * for datasyncs on files that have no dirty metadata.
  */
-int
+static int
 xfs_fs_commit_blocks(
 	struct inode		*inode,
 	struct iomap		*maps,
@@ -332,3 +332,9 @@ xfs_fs_commit_blocks(
 	xfs_iunlock(ip, XFS_IOLOCK_EXCL);
 	return error;
 }
+
+const struct exportfs_block_ops xfs_export_block_ops = {
+	.get_uuid		= xfs_fs_get_uuid,
+	.map_blocks		= xfs_fs_map_blocks,
+	.commit_blocks		= xfs_fs_commit_blocks,
+};
diff --git a/fs/xfs/xfs_pnfs.h b/fs/xfs/xfs_pnfs.h
index 940c6c2ad88c..bf43b2009e4c 100644
--- a/fs/xfs/xfs_pnfs.h
+++ b/fs/xfs/xfs_pnfs.h
@@ -2,13 +2,9 @@
 #ifndef _XFS_PNFS_H
 #define _XFS_PNFS_H 1
 
-#ifdef CONFIG_EXPORTFS_BLOCK_OPS
-int xfs_fs_get_uuid(struct super_block *sb, u8 *buf, u32 *len, u64 *offset);
-int xfs_fs_map_blocks(struct inode *inode, loff_t offset, u64 length,
-		struct iomap *iomap, bool write, u32 *device_generation);
-int xfs_fs_commit_blocks(struct inode *inode, struct iomap *maps, int nr_maps,
-		struct iattr *iattr);
+#include <linux/exportfs_block.h>
 
+#ifdef CONFIG_EXPORTFS_BLOCK_OPS
 int xfs_break_leased_layouts(struct inode *inode, uint *iolock,
 		bool *did_unlock);
 #else
@@ -18,4 +14,7 @@ xfs_break_leased_layouts(struct inode *inode, uint *iolock, bool *did_unlock)
 	return 0;
 }
 #endif /* CONFIG_EXPORTFS_BLOCK_OPS */
+
+extern const struct exportfs_block_ops xfs_export_block_ops;
+
 #endif /* _XFS_PNFS_H */
diff --git a/include/linux/exportfs.h b/include/linux/exportfs.h
index 8bcdba28b406..c835bc64f4fa 100644
--- a/include/linux/exportfs.h
+++ b/include/linux/exportfs.h
@@ -6,9 +6,8 @@
 #include <linux/path.h>
 
 struct dentry;
-struct iattr;
+struct exportfs_block_ops;
 struct inode;
-struct iomap;
 struct super_block;
 struct vfsmount;
 
@@ -260,19 +259,13 @@ struct handle_to_path_ctx {
  * @commit_metadata:
  *    @commit_metadata should commit metadata changes to stable storage.
  *
- * @get_uuid:
- *    Get a filesystem unique signature exposed to clients.
- *
- * @map_blocks:
- *    Map and, if necessary, allocate blocks for a layout.
- *
- * @commit_blocks:
- *    Commit blocks in a layout once the client is done with them.
- *
  * @flags:
  *    Allows the filesystem to communicate to nfsd that it may want to do things
  *    differently when dealing with it.
  *
+ * @block_ops:
+ *    Operations for layout grants to block on the underlying device.
+ *
  * Locking rules:
  *    get_parent is called with child->d_inode->i_rwsem down
  *    get_name is not (which is possibly inconsistent)
@@ -290,12 +283,6 @@ struct export_operations {
 	struct dentry * (*get_parent)(struct dentry *child);
 	int (*commit_metadata)(struct inode *inode);
 
-	int (*get_uuid)(struct super_block *sb, u8 *buf, u32 *len, u64 *offset);
-	int (*map_blocks)(struct inode *inode, loff_t offset,
-			  u64 len, struct iomap *iomap,
-			  bool write, u32 *device_generation);
-	int (*commit_blocks)(struct inode *inode, struct iomap *iomaps,
-			     int nr_iomaps, struct iattr *iattr);
 	int (*permission)(struct handle_to_path_ctx *ctx, unsigned int oflags);
 	struct file * (*open)(const struct path *path, unsigned int oflags);
 #define	EXPORT_OP_NOWCC			(0x1) /* don't collect v3 wcc data */
@@ -308,6 +295,10 @@ struct export_operations {
 #define EXPORT_OP_FLUSH_ON_CLOSE	(0x20) /* fs flushes file data on close */
 #define EXPORT_OP_NOLOCKS		(0x40) /* no file locking support */
 	unsigned long	flags;
+
+#ifdef CONFIG_EXPORTFS_BLOCK_OPS
+	const struct exportfs_block_ops *block_ops;
+#endif
 };
 
 /**
diff --git a/include/linux/exportfs_block.h b/include/linux/exportfs_block.h
new file mode 100644
index 000000000000..1f52fea8e4dc
--- /dev/null
+++ b/include/linux/exportfs_block.h
@@ -0,0 +1,39 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (c) 2014-2026 Christoph Hellwig.
+ *
+ * Support for exportfs-based layout grants for direct block device access.
+ */
+#ifndef LINUX_EXPORTFS_BLOCK_H
+#define LINUX_EXPORTFS_BLOCK_H 1
+
+#include <linux/types.h>
+
+struct iattr;
+struct inode;
+struct iomap;
+struct super_block;
+
+struct exportfs_block_ops {
+	/*
+	 * Get the in-band device unique signature exposed to clients.
+	 */
+	int (*get_uuid)(struct super_block *sb, u8 *buf, u32 *len, u64 *offset);
+
+	/*
+	 * Map blocks for direct block access.
+	 * If @write is %true, also allocate the blocks for the range if needed.
+	 */
+	int (*map_blocks)(struct inode *inode, loff_t offset, u64 len,
+			struct iomap *iomap, bool write,
+			u32 *device_generation);
+
+	/*
+	 * Commit blocks previously handed out by ->map_blocks and written to by
+	 * the client.
+	 */
+	int (*commit_blocks)(struct inode *inode, struct iomap *iomaps,
+			int nr_iomaps, struct iattr *iattr);
+};
+
+#endif /* LINUX_EXPORTFS_BLOCK_H */
-- 
2.47.3

[PATCH 3/4] exportfs: don't pass struct iattr to ->commit_blocks

[Christoph Hellwig]

The only thing ->commit_blocks really needs is the new size, with a magic
-1 placeholder 0 for "do not change the size" because it only ever
extends the size.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jeff Layton <jlayton@kernel.org
---
 fs/nfsd/blocklayout.c          | 12 ++----------
 fs/xfs/xfs_pnfs.c              | 19 ++++++++++---------
 include/linux/exportfs_block.h |  3 +--
 3 files changed, 13 insertions(+), 21 deletions(-)

diff --git a/fs/nfsd/blocklayout.c b/fs/nfsd/blocklayout.c
index 3cc3b47361e2..23c0e4d0ff34 100644
--- a/fs/nfsd/blocklayout.c
+++ b/fs/nfsd/blocklayout.c
@@ -179,7 +179,6 @@ static __be32
 nfsd4_block_commit_blocks(struct inode *inode, struct nfsd4_layoutcommit *lcp,
 		struct iomap *iomaps, int nr_iomaps)
 {
-	struct iattr iattr = { .ia_valid = 0 };
 	int error;
 
 	/*
@@ -191,16 +190,9 @@ nfsd4_block_commit_blocks(struct inode *inode, struct nfsd4_layoutcommit *lcp,
 	 * timestamp is a "may" condition, and clients that want to force a
 	 * specific timestamp should send a separate SETATTR in the compound.
 	 */
-	iattr.ia_valid |= ATTR_ATIME | ATTR_CTIME | ATTR_MTIME;
-	iattr.ia_atime = iattr.ia_ctime = iattr.ia_mtime = current_time(inode);
-
-	if (lcp->lc_size_chg) {
-		iattr.ia_valid |= ATTR_SIZE;
-		iattr.ia_size = lcp->lc_newsize;
-	}
-
 	error = inode->i_sb->s_export_op->block_ops->commit_blocks(inode,
-			iomaps, nr_iomaps, &iattr);
+			iomaps, nr_iomaps,
+			lcp->lc_size_chg ? lcp->lc_newsize : 0);
 	kfree(iomaps);
 	return nfserrno(error);
 }
diff --git a/fs/xfs/xfs_pnfs.c b/fs/xfs/xfs_pnfs.c
index 12e083f1b9ba..7d689bb2efd9 100644
--- a/fs/xfs/xfs_pnfs.c
+++ b/fs/xfs/xfs_pnfs.c
@@ -257,23 +257,22 @@ xfs_fs_commit_blocks(
 	struct inode		*inode,
 	struct iomap		*maps,
 	int			nr_maps,
-	struct iattr		*iattr)
+	loff_t			new_size)
 {
 	struct xfs_inode	*ip = XFS_I(inode);
 	struct xfs_mount	*mp = ip->i_mount;
 	struct xfs_trans	*tp;
+	struct timespec64	now;
 	bool			update_isize = false;
 	int			error, i;
 	loff_t			size;
 
-	ASSERT(iattr->ia_valid & (ATTR_ATIME|ATTR_CTIME|ATTR_MTIME));
-
 	xfs_ilock(ip, XFS_IOLOCK_EXCL);
 
 	size = i_size_read(inode);
-	if ((iattr->ia_valid & ATTR_SIZE) && iattr->ia_size > size) {
+	if (new_size > size) {
 		update_isize = true;
-		size = iattr->ia_size;
+		size = new_size;
 	}
 
 	for (i = 0; i < nr_maps; i++) {
@@ -318,11 +317,13 @@ xfs_fs_commit_blocks(
 	xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
 	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 
-	ASSERT(!(iattr->ia_valid & (ATTR_UID | ATTR_GID)));
-	setattr_copy(&nop_mnt_idmap, inode, iattr);
+	now = inode_set_ctime_current(inode);
+	inode_set_atime_to_ts(inode, now);
+	inode_set_mtime_to_ts(inode, now);
+
 	if (update_isize) {
-		i_size_write(inode, iattr->ia_size);
-		ip->i_disk_size = iattr->ia_size;
+		i_size_write(inode, new_size);
+		ip->i_disk_size = new_size;
 	}
 
 	xfs_trans_set_sync(tp);
diff --git a/include/linux/exportfs_block.h b/include/linux/exportfs_block.h
index 1f52fea8e4dc..d1dec4689b14 100644
--- a/include/linux/exportfs_block.h
+++ b/include/linux/exportfs_block.h
@@ -9,7 +9,6 @@
 
 #include <linux/types.h>
 
-struct iattr;
 struct inode;
 struct iomap;
 struct super_block;
@@ -33,7 +32,7 @@ struct exportfs_block_ops {
 	 * the client.
 	 */
 	int (*commit_blocks)(struct inode *inode, struct iomap *iomaps,
-			int nr_iomaps, struct iattr *iattr);
+			int nr_iomaps, loff_t new_size);
 };
 
 #endif /* LINUX_EXPORTFS_BLOCK_H */
-- 
2.47.3

[PATCH 4/4] exportfs,nfsd: rework checking for layout-based block device access support

[Christoph Hellwig]

Currently NFSD hard codes checking support for block-style layouts.
Lift the checks into a file system-helper and provide a exportfs-level
helper to implement the typical checks.

This prepares for supporting block layout export of multiple devices
per file system.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
---
 fs/nfsd/export.c               |  3 +-
 fs/nfsd/nfs4layouts.c          | 26 +++++------------
 fs/xfs/xfs_pnfs.c              | 13 +++++++++
 include/linux/exportfs_block.h | 52 +++++++++++++++++++++++++++++++++-
 4 files changed, 73 insertions(+), 21 deletions(-)

diff --git a/fs/nfsd/export.c b/fs/nfsd/export.c
index 8e8a76a44ff0..e20298f9212f 100644
--- a/fs/nfsd/export.c
+++ b/fs/nfsd/export.c
@@ -735,7 +735,8 @@ static int svc_export_parse(struct cache_detail *cd, char *mesg, int mlen)
 			goto out4;
 		err = 0;
 
-		nfsd4_setup_layout_type(&exp);
+		if (exp.ex_flags & NFSEXP_PNFS)
+			nfsd4_setup_layout_type(&exp);
 	}
 
 	expp = svc_export_lookup(&exp);
diff --git a/fs/nfsd/nfs4layouts.c b/fs/nfsd/nfs4layouts.c
index 6c1ff21b83a2..0b51eabbafde 100644
--- a/fs/nfsd/nfs4layouts.c
+++ b/fs/nfsd/nfs4layouts.c
@@ -2,7 +2,6 @@
 /*
  * Copyright (c) 2014 Christoph Hellwig.
  */
-#include <linux/blkdev.h>
 #include <linux/exportfs_block.h>
 #include <linux/kmod.h>
 #include <linux/file.h>
@@ -126,28 +125,17 @@ nfsd4_set_deviceid(struct nfsd4_deviceid *id, const struct svc_fh *fhp,
 
 void nfsd4_setup_layout_type(struct svc_export *exp)
 {
-#if defined(CONFIG_NFSD_BLOCKLAYOUT) || defined(CONFIG_NFSD_SCSILAYOUT)
 	struct super_block *sb = exp->ex_path.mnt->mnt_sb;
-	const struct exportfs_block_ops *bops = sb->s_export_op->block_ops;
-#endif
-
-	if (!(exp->ex_flags & NFSEXP_PNFS))
-		return;
+	expfs_block_layouts_t block_supported = exportfs_layouts_supported(sb);
 
-#ifdef CONFIG_NFSD_FLEXFILELAYOUT
-	exp->ex_layout_types |= 1 << LAYOUT_FLEX_FILES;
-#endif
-#ifdef CONFIG_NFSD_BLOCKLAYOUT
-	if (bops && bops->get_uuid && bops->map_blocks && bops->commit_blocks)
+	if (IS_ENABLED(CONFIG_NFSD_FLEXFILELAYOUT))
+		exp->ex_layout_types |= 1 << LAYOUT_FLEX_FILES;
+	if (IS_ENABLED(CONFIG_NFSD_BLOCKLAYOUT) &&
+	    (block_supported & EXPFS_BLOCK_IN_BAND_ID))
 		exp->ex_layout_types |= 1 << LAYOUT_BLOCK_VOLUME;
-#endif
-#ifdef CONFIG_NFSD_SCSILAYOUT
-	if (bops && bops->map_blocks && bops->commit_blocks &&
-	    sb->s_bdev &&
-	    sb->s_bdev->bd_disk->fops->pr_ops &&
-	    sb->s_bdev->bd_disk->fops->get_unique_id)
+	if (IS_ENABLED(CONFIG_NFSD_SCSILAYOUT) &&
+	    (block_supported & EXPFS_BLOCK_OUT_OF_BAND_ID))
 		exp->ex_layout_types |= 1 << LAYOUT_SCSI;
-#endif
 }
 
 void nfsd4_close_layout(struct nfs4_layout_stateid *ls)
diff --git a/fs/xfs/xfs_pnfs.c b/fs/xfs/xfs_pnfs.c
index 7d689bb2efd9..266a07601e8d 100644
--- a/fs/xfs/xfs_pnfs.c
+++ b/fs/xfs/xfs_pnfs.c
@@ -13,6 +13,7 @@
 #include "xfs_bmap.h"
 #include "xfs_iomap.h"
 #include "xfs_pnfs.h"
+#include <linux/exportfs_block.h>
 
 /*
  * Ensure that we do not have any outstanding pNFS layouts that can be used by
@@ -45,6 +46,17 @@ xfs_break_leased_layouts(
 	return error;
 }
 
+static expfs_block_layouts_t
+xfs_fs_layouts_supported(
+	struct super_block	*sb)
+{
+	expfs_block_layouts_t	supported = EXPFS_BLOCK_IN_BAND_ID;
+
+	if (exportfs_bdev_supports_out_of_band_id(sb->s_bdev))
+		supported |= EXPFS_BLOCK_OUT_OF_BAND_ID;
+	return supported;
+}
+
 /*
  * Get a unique ID including its location so that the client can identify
  * the exported device.
@@ -335,6 +347,7 @@ xfs_fs_commit_blocks(
 }
 
 const struct exportfs_block_ops xfs_export_block_ops = {
+	.layouts_supported	= xfs_fs_layouts_supported,
 	.get_uuid		= xfs_fs_get_uuid,
 	.map_blocks		= xfs_fs_map_blocks,
 	.commit_blocks		= xfs_fs_commit_blocks,
diff --git a/include/linux/exportfs_block.h b/include/linux/exportfs_block.h
index d1dec4689b14..de519b7b599b 100644
--- a/include/linux/exportfs_block.h
+++ b/include/linux/exportfs_block.h
@@ -7,13 +7,35 @@
 #ifndef LINUX_EXPORTFS_BLOCK_H
 #define LINUX_EXPORTFS_BLOCK_H 1
 
-#include <linux/types.h>
+#include <linux/blkdev.h>
+#include <linux/exportfs.h>
+#include <linux/fs.h>
 
 struct inode;
 struct iomap;
 struct super_block;
 
+/*
+ * There are the two types of block-style layout support:
+ *  - In-band implies a device identified by a unique cookie inside the actual
+ *    device address space checked by the ->get_uuid method as used by the pNFS
+ *    block layout.  This is a bit dangerous and deprecated.
+ *  - Out of band implies identification by out of band unique identifiers
+ *    specified by the storage protocol, which is much safer and used by the
+ *    pNFS SCSI/NVMe layouts.
+ */
+typedef unsigned int __bitwise expfs_block_layouts_t;
+#define EXPFS_BLOCK_FLAG(__bit) \
+	((__force expfs_block_layouts_t)(1u << __bit))
+#define EXPFS_BLOCK_IN_BAND_ID		EXPFS_BLOCK_FLAG(0)
+#define EXPFS_BLOCK_OUT_OF_BAND_ID	EXPFS_BLOCK_FLAG(1)
+
 struct exportfs_block_ops {
+	/*
+	 * Returns the EXPFS_BLOCK_* bitmap of supported layout types.
+	 */
+	expfs_block_layouts_t (*layouts_supported)(struct super_block *sb);
+
 	/*
 	 * Get the in-band device unique signature exposed to clients.
 	 */
@@ -35,4 +57,32 @@ struct exportfs_block_ops {
 			int nr_iomaps, loff_t new_size);
 };
 
+static inline bool
+exportfs_bdev_supports_out_of_band_id(struct block_device *bdev)
+{
+	return bdev->bd_disk->fops->pr_ops &&
+		bdev->bd_disk->fops->get_unique_id;
+}
+
+#ifdef CONFIG_EXPORTFS_BLOCK_OPS
+static inline expfs_block_layouts_t
+exportfs_layouts_supported(struct super_block *sb)
+{
+	const struct exportfs_block_ops *bops = sb->s_export_op->block_ops;
+
+	if (!bops ||
+	    !bops->layouts_supported ||
+	    WARN_ON_ONCE(!bops->map_blocks) ||
+	    WARN_ON_ONCE(!bops->commit_blocks))
+		return 0;
+	return bops->layouts_supported(sb);
+}
+#else
+static inline expfs_block_layouts_t
+exportfs_layouts_supported(struct super_block *sb)
+{
+	return 0;
+}
+#endif /* CONFIG_EXPORTFS_BLOCK_OPS */
+
 #endif /* LINUX_EXPORTFS_BLOCK_H */
-- 
2.47.3

Re: cleanup block-style layouts exports v2

[Chuck Lever]

On Wed, Apr 1, 2026, at 10:40 AM, Christoph Hellwig wrote:
> Hi all,
>
> this series cleanups the exportfs support for block-style layouts that
> provide direct block device access.  This is preparation for supporting
> exportfs of more than a single device per file system.
>
> Changes since v1:
>  - consity struct exportfs_block_ops
>  - fix spelling
>
> Changes since the multi-device export series:
>  - check for NULL bops in nfsd4_setup_layout_type
>  - clearly document why we are ignoring loca_time_modify
>
> Diffstat:
>  MAINTAINERS                    |    2 
>  fs/nfsd/blocklayout.c          |   37 +++++++----------
>  fs/nfsd/export.c               |    3 -
>  fs/nfsd/nfs4layouts.c          |   29 +++----------
>  fs/xfs/xfs_export.c            |    4 -
>  fs/xfs/xfs_pnfs.c              |   44 ++++++++++++++------
>  fs/xfs/xfs_pnfs.h              |   11 ++---
>  include/linux/exportfs.h       |   25 +++--------
>  include/linux/exportfs_block.h |   88 +++++++++++++++++++++++++++++++++++++++++
>  9 files changed, 162 insertions(+), 81 deletions(-)

Christian, are you OK if I take this series through the NFSD tree?


-- 
Chuck Lever

Re: cleanup block-style layouts exports v2

[Christian Brauner]

On Wed, Apr 01, 2026 at 04:31:10PM -0400, Chuck Lever wrote:
> 
> 
> On Wed, Apr 1, 2026, at 10:40 AM, Christoph Hellwig wrote:
> > Hi all,
> >
> > this series cleanups the exportfs support for block-style layouts that
> > provide direct block device access.  This is preparation for supporting
> > exportfs of more than a single device per file system.
> >
> > Changes since v1:
> >  - consity struct exportfs_block_ops
> >  - fix spelling
> >
> > Changes since the multi-device export series:
> >  - check for NULL bops in nfsd4_setup_layout_type
> >  - clearly document why we are ignoring loca_time_modify
> >
> > Diffstat:
> >  MAINTAINERS                    |    2 
> >  fs/nfsd/blocklayout.c          |   37 +++++++----------
> >  fs/nfsd/export.c               |    3 -
> >  fs/nfsd/nfs4layouts.c          |   29 +++----------
> >  fs/xfs/xfs_export.c            |    4 -
> >  fs/xfs/xfs_pnfs.c              |   44 ++++++++++++++------
> >  fs/xfs/xfs_pnfs.h              |   11 ++---
> >  include/linux/exportfs.h       |   25 +++--------
> >  include/linux/exportfs_block.h |   88 +++++++++++++++++++++++++++++++++++++++++
> >  9 files changed, 162 insertions(+), 81 deletions(-)
> 
> Christian, are you OK if I take this series through the NFSD tree?

Hm, I generally prefer infrastructure to go through the VFS tree.
You can get a stable branch ofc.

Re: cleanup block-style layouts exports v2

[Christoph Hellwig]

On Thu, Apr 09, 2026 at 03:26:09PM +0200, Christian Brauner wrote:
> > Christian, are you OK if I take this series through the NFSD tree?
> 
> Hm, I generally prefer infrastructure to go through the VFS tree.
> You can get a stable branch ofc.

Communicating this earlier would be helpful.  If we switch to a new
tree base we're going to miss this merge window.

Re: cleanup block-style layouts exports v2

[Chuck Lever]

From: Chuck Lever <chuck.lever@oracle.com>

On Wed, 01 Apr 2026 16:40:21 +0200, Christoph Hellwig wrote:
> this series cleanups the exportfs support for block-style layouts that
> provide direct block device access.  This is preparation for supporting
> exportfs of more than a single device per file system.
> 
> Changes since v1:
>  - consity struct exportfs_block_ops
>  - fix spelling
> 
> [...]

Applied to nfsd-testing, thanks!

[1/4] nfsd/blocklayout: always ignore loca_time_modify
      commit: ff6bb92c2f41eac178f9886d15a62cb7f8acf111
[2/4] exportfs: split out the ops for layout-based block device access
      commit: 86cc64ab3045f7130c2d2d7c458646038282938a
[3/4] exportfs: don't pass struct iattr to ->commit_blocks
      commit: 949378be2cd289d749ef9a826ea6cf376bca973e
[4/4] exportfs,nfsd: rework checking for layout-based block device access support
      commit: e0259785dffcb12f6850450344ab0f99b6283d60

--
Chuck Lever