[19/20] xfs: implement pNFS export operations
diff mbox

Message ID 1421925006-24231-20-git-send-email-hch@lst.de
State New, archived
Headers show

Commit Message

Christoph Hellwig Jan. 22, 2015, 11:10 a.m. UTC
Add operations to export pNFS block layouts from an XFS filesystem.  See
the previous commit adding the operations for an explanation of them.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/xfs/Makefile     |   1 +
 fs/xfs/xfs_export.c |   6 ++
 fs/xfs/xfs_fsops.c  |   2 +
 fs/xfs/xfs_iops.c   |   2 +-
 fs/xfs/xfs_iops.h   |   1 +
 fs/xfs/xfs_mount.h  |  11 +++
 fs/xfs/xfs_pnfs.c   | 243 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 fs/xfs/xfs_pnfs.h   |  11 +++
 8 files changed, 276 insertions(+), 1 deletion(-)
 create mode 100644 fs/xfs/xfs_pnfs.c
 create mode 100644 fs/xfs/xfs_pnfs.h

Comments

Dave Chinner Feb. 5, 2015, 12:47 a.m. UTC | #1
On Thu, Jan 22, 2015 at 12:10:05PM +0100, Christoph Hellwig wrote:
> Add operations to export pNFS block layouts from an XFS filesystem.  See
> the previous commit adding the operations for an explanation of them.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Note that I haven't applied this patch, or attempted to compile it
yet....

> diff --git a/fs/xfs/Makefile b/fs/xfs/Makefile
> index d617999..df68285 100644
> --- a/fs/xfs/Makefile
> +++ b/fs/xfs/Makefile
> @@ -121,3 +121,4 @@ xfs-$(CONFIG_XFS_POSIX_ACL)	+= xfs_acl.o
>  xfs-$(CONFIG_PROC_FS)		+= xfs_stats.o
>  xfs-$(CONFIG_SYSCTL)		+= xfs_sysctl.o
>  xfs-$(CONFIG_COMPAT)		+= xfs_ioctl32.o
> +xfs-$(CONFIG_NFSD_PNFS)		+= xfs_pnfs.o

... because I'll have to jump through hoops to get it to compile, I
think.

> diff --git a/fs/xfs/xfs_fsops.c b/fs/xfs/xfs_fsops.c
> index 74c6211..99465ba 100644
> --- a/fs/xfs/xfs_fsops.c
> +++ b/fs/xfs/xfs_fsops.c
> @@ -602,6 +602,8 @@ xfs_growfs_data(
>  	if (!mutex_trylock(&mp->m_growlock))
>  		return -EWOULDBLOCK;
>  	error = xfs_growfs_data_private(mp, in);
> +	if (!error)
> +		mp->m_generation++;
>  	mutex_unlock(&mp->m_growlock);
>  	return error;
>  }

Even on error I think we should bump this. Errors can come from
secondary superblock updates after the filesystem has been grown,
hence an error is not a reliable indication of whether the layout
has changed or not.

> +int
> +xfs_fs_get_uuid(
> +	struct super_block	*sb,
> +	u8			*buf,
> +	u32			*len,
> +	u64			*offset)
> +{
> +	struct xfs_mount	*mp = XFS_M(sb);
> +
> +	if (*len < sizeof(uuid_t))
> +		return -EINVAL;
> +
> +	memcpy(buf, &mp->m_sb.sb_uuid, sizeof(uuid_t));
> +	*len = sizeof(uuid_t);
> +	*offset = offsetof(struct xfs_dsb, sb_uuid);

What purpose does the offset serve here? I can't tell from the usage
in the PNFS code. Can we ignore offset - as it seems entirely
arbitrary - and still have this work? Either way, comment please.


> +static void
> +xfs_bmbt_to_iomap(
> +	struct xfs_inode	*ip,
> +	struct iomap		*iomap,
> +	struct xfs_bmbt_irec	*imap)
> +{
> +	struct xfs_mount	*mp = ip->i_mount;
> +
> +	if (imap->br_startblock == HOLESTARTBLOCK) {
> +		iomap->blkno = -1;
> +		iomap->type = IOMAP_HOLE;
> +	} else if (imap->br_startblock == DELAYSTARTBLOCK) {
> +		iomap->blkno = -1;
> +		iomap->type = IOMAP_DELALLOC;

I'd like to see a IOMAP_NULL_BLOCK define here for the -1 value,
say:

#define IOMAP_NULL_BLOCK	-1LL

> +int
> +xfs_fs_map_blocks(
> +	struct inode		*inode,
> +	loff_t			offset,
> +	u64			length,
> +	struct iomap		*iomap,
> +	bool			write,
> +	u32			*device_generation)
> +{
> +	struct xfs_inode	*ip = XFS_I(inode);
> +	struct xfs_mount	*mp = ip->i_mount;
> +	struct xfs_bmbt_irec	imap;
> +	xfs_fileoff_t		offset_fsb, end_fsb;
> +	loff_t			limit;
> +	int			bmapi_flags = XFS_BMAPI_ENTIRE;
> +	int			nimaps = 1;
> +	uint			lock_flags;
> +	int			error = 0;
> +
> +	if (XFS_FORCED_SHUTDOWN(mp))
> +		return -EIO;
> +	if (XFS_IS_REALTIME_INODE(ip))
> +		return -ENXIO;

OK, so we are not mapping realtime inodes here. Any specific reason?
FWIW, that also means you can use XFS_FSB_TO_DADDR() in the iomap
mapping as xfs_fsb_to_db() is only needed if we might be mapping
realtime extents...

> +	for (i = 0; i < nr_maps; i++) {
> +		u64 start, length, end;
> +
> +		start = maps[i].offset;
> +		if (start > size)
> +			continue;
> +
> +		end = start + maps[i].length;
> +		if (end > size)
> +			end = size;
> +
> +		length = end - start;
> +		if (!length)
> +			continue;
> +	
   ^^^^^
Stray whitespace

> +	tp = xfs_trans_alloc(mp, XFS_TRANS_SETATTR_NOT_SIZE);
> +	error = xfs_trans_reserve(tp, &M_RES(mp)->tr_ichange, 0, 0);
> +	if (error)
> +		goto out_drop_iolock;
> +
> +	xfs_ilock(ip, XFS_ILOCK_EXCL);
> +	xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
> +	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
> +
> +	xfs_setattr_time(ip, iattr);
> +	if (iattr->ia_valid & ATTR_SIZE) {
> +		if (iattr->ia_size > i_size_read(inode)) {
> +			i_size_write(inode, iattr->ia_size);
> +			ip->i_d.di_size = iattr->ia_size;
> +		}
> +	}

The concern I have about this is that extending the file size can
expose uninitialised blocks beyond the old EOF. That can happen if
delayed allocation has previously been done on the file and we
haven't trimmed the excess beyond EOF back yet. I know the pnfs
server is not aimed at mixed usage, but it still makes me
uncomfortable in the case where you have normal NFS and PNFS clients
accessing the same files...

> +	xfs_trans_set_sync(tp);
> +	error = xfs_trans_commit(tp, 0);

I just had a thought about these sync transctions - could the NFS
server handle persistence of the maps via ->commit_metadata?

Cheers,

Dave.
Christoph Hellwig Feb. 5, 2015, 7:08 a.m. UTC | #2
On Thu, Feb 05, 2015 at 11:47:58AM +1100, Dave Chinner wrote:
> > +++ b/fs/xfs/Makefile
> > @@ -121,3 +121,4 @@ xfs-$(CONFIG_XFS_POSIX_ACL)	+= xfs_acl.o
> >  xfs-$(CONFIG_PROC_FS)		+= xfs_stats.o
> >  xfs-$(CONFIG_SYSCTL)		+= xfs_sysctl.o
> >  xfs-$(CONFIG_COMPAT)		+= xfs_ioctl32.o
> > +xfs-$(CONFIG_NFSD_PNFS)		+= xfs_pnfs.o
> 
> ... because I'll have to jump through hoops to get it to compile, I
> think.

Just get the whole git tree from

	git://git.infradead.org/users/hch/pnfs.git pnfsd-for-3.20-3

> > diff --git a/fs/xfs/xfs_fsops.c b/fs/xfs/xfs_fsops.c
> > index 74c6211..99465ba 100644
> > --- a/fs/xfs/xfs_fsops.c
> > +++ b/fs/xfs/xfs_fsops.c
> > @@ -602,6 +602,8 @@ xfs_growfs_data(
> >  	if (!mutex_trylock(&mp->m_growlock))
> >  		return -EWOULDBLOCK;
> >  	error = xfs_growfs_data_private(mp, in);
> > +	if (!error)
> > +		mp->m_generation++;
> >  	mutex_unlock(&mp->m_growlock);
> >  	return error;
> >  }
> 
> Even on error I think we should bump this. Errors can come from
> secondary superblock updates after the filesystem has been grown,
> hence an error is not a reliable indication of whether the layout
> has changed or not.

Ok.
> 
> > +int
> > +xfs_fs_get_uuid(
> > +	struct super_block	*sb,
> > +	u8			*buf,
> > +	u32			*len,
> > +	u64			*offset)
> > +{
> > +	struct xfs_mount	*mp = XFS_M(sb);
> > +
> > +	if (*len < sizeof(uuid_t))
> > +		return -EINVAL;
> > +
> > +	memcpy(buf, &mp->m_sb.sb_uuid, sizeof(uuid_t));
> > +	*len = sizeof(uuid_t);
> > +	*offset = offsetof(struct xfs_dsb, sb_uuid);
> 
> What purpose does the offset serve here? I can't tell from the usage
> in the PNFS code. Can we ignore offset - as it seems entirely
> arbitrary - and still have this work? Either way, comment please.

The get_uuid methods gets content and location of the uuid so that
the client can find the disks.  The offset simply is part of the wire
protocol.

> I'd like to see a IOMAP_NULL_BLOCK define here for the -1 value,
> say:
> 
> #define IOMAP_NULL_BLOCK	-1LL

Ok.

> OK, so we are not mapping realtime inodes here. Any specific reason?

The realtime device doesn't have a way for the client to find it, as
it doesn't have its own superblockuuids.

> FWIW, that also means you can use XFS_FSB_TO_DADDR() in the iomap
> mapping as xfs_fsb_to_db() is only needed if we might be mapping
> realtime extents...

ok.

> > +	tp = xfs_trans_alloc(mp, XFS_TRANS_SETATTR_NOT_SIZE);
> > +	error = xfs_trans_reserve(tp, &M_RES(mp)->tr_ichange, 0, 0);
> > +	if (error)
> > +		goto out_drop_iolock;
> > +
> > +	xfs_ilock(ip, XFS_ILOCK_EXCL);
> > +	xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
> > +	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
> > +
> > +	xfs_setattr_time(ip, iattr);
> > +	if (iattr->ia_valid & ATTR_SIZE) {
> > +		if (iattr->ia_size > i_size_read(inode)) {
> > +			i_size_write(inode, iattr->ia_size);
> > +			ip->i_d.di_size = iattr->ia_size;
> > +		}
> > +	}
> 
> The concern I have about this is that extending the file size can
> expose uninitialised blocks beyond the old EOF. That can happen if
> delayed allocation has previously been done on the file and we
> haven't trimmed the excess beyond EOF back yet. I know the pnfs
> server is not aimed at mixed usage, but it still makes me
> uncomfortable in the case where you have normal NFS and PNFS clients
> accessing the same files...

The protocol only allows to commit to a size that we previously
returned a layout for, which means we already have allocated space
for it at same time.  For robustness reasons a sanity check might make
sense, though.

> > +	xfs_trans_set_sync(tp);
> > +	error = xfs_trans_commit(tp, 0);
> 
> I just had a thought about these sync transctions - could the NFS
> server handle persistence of the maps via ->commit_metadata?

It probably could, but that wouldn't buy us anything over just committing
the transaction synchronously.
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Patch
diff mbox

diff --git a/fs/xfs/Makefile b/fs/xfs/Makefile
index d617999..df68285 100644
--- a/fs/xfs/Makefile
+++ b/fs/xfs/Makefile
@@ -121,3 +121,4 @@  xfs-$(CONFIG_XFS_POSIX_ACL)	+= xfs_acl.o
 xfs-$(CONFIG_PROC_FS)		+= xfs_stats.o
 xfs-$(CONFIG_SYSCTL)		+= xfs_sysctl.o
 xfs-$(CONFIG_COMPAT)		+= xfs_ioctl32.o
+xfs-$(CONFIG_NFSD_PNFS)		+= xfs_pnfs.o
diff --git a/fs/xfs/xfs_export.c b/fs/xfs/xfs_export.c
index 5eb4a14..b97359b 100644
--- a/fs/xfs/xfs_export.c
+++ b/fs/xfs/xfs_export.c
@@ -30,6 +30,7 @@ 
 #include "xfs_trace.h"
 #include "xfs_icache.h"
 #include "xfs_log.h"
+#include "xfs_pnfs.h"
 
 /*
  * Note that we only accept fileids which are long enough rather than allow
@@ -245,4 +246,9 @@  const struct export_operations xfs_export_operations = {
 	.fh_to_parent		= xfs_fs_fh_to_parent,
 	.get_parent		= xfs_fs_get_parent,
 	.commit_metadata	= xfs_fs_nfs_commit_metadata,
+#ifdef CONFIG_NFSD_PNFS
+	.get_uuid		= xfs_fs_get_uuid,
+	.map_blocks		= xfs_fs_map_blocks,
+	.commit_blocks		= xfs_fs_commit_blocks,
+#endif
 };
diff --git a/fs/xfs/xfs_fsops.c b/fs/xfs/xfs_fsops.c
index 74c6211..99465ba 100644
--- a/fs/xfs/xfs_fsops.c
+++ b/fs/xfs/xfs_fsops.c
@@ -602,6 +602,8 @@  xfs_growfs_data(
 	if (!mutex_trylock(&mp->m_growlock))
 		return -EWOULDBLOCK;
 	error = xfs_growfs_data_private(mp, in);
+	if (!error)
+		mp->m_generation++;
 	mutex_unlock(&mp->m_growlock);
 	return error;
 }
diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c
index c50311c..6ff84e8 100644
--- a/fs/xfs/xfs_iops.c
+++ b/fs/xfs/xfs_iops.c
@@ -496,7 +496,7 @@  xfs_setattr_mode(
 	inode->i_mode |= mode & ~S_IFMT;
 }
 
-static void
+void
 xfs_setattr_time(
 	struct xfs_inode	*ip,
 	struct iattr		*iattr)
diff --git a/fs/xfs/xfs_iops.h b/fs/xfs/xfs_iops.h
index 1c34e43..ea7a98e 100644
--- a/fs/xfs/xfs_iops.h
+++ b/fs/xfs/xfs_iops.h
@@ -32,6 +32,7 @@  extern void xfs_setup_inode(struct xfs_inode *);
  */
 #define XFS_ATTR_NOACL		0x01	/* Don't call posix_acl_chmod */
 
+extern void xfs_setattr_time(struct xfs_inode *ip, struct iattr *iattr);
 extern int xfs_setattr_nonsize(struct xfs_inode *ip, struct iattr *vap,
 			       int flags);
 extern int xfs_setattr_size(struct xfs_inode *ip, struct iattr *vap);
diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h
index 22ccf69..12925d5 100644
--- a/fs/xfs/xfs_mount.h
+++ b/fs/xfs/xfs_mount.h
@@ -175,6 +175,17 @@  typedef struct xfs_mount {
 	struct workqueue_struct	*m_reclaim_workqueue;
 	struct workqueue_struct	*m_log_workqueue;
 	struct workqueue_struct *m_eofblocks_workqueue;
+
+	/*
+	 * Generation of the filesysyem layout.  This is incremented by each
+	 * growfs, and used by the pNFS server to ensure the client updates
+	 * its view of the block device once it gets a layout that might
+	 * reference the newly added blocks.  Does not need to be persistent
+	 * as long as we only allow file system size increments, but if we
+	 * ever support shrinks it would have to be persisted in addition
+	 * to various other kinds of pain inflicted on the pNFS server.
+	 */
+	__uint32_t		m_generation;
 } xfs_mount_t;
 
 /*
diff --git a/fs/xfs/xfs_pnfs.c b/fs/xfs/xfs_pnfs.c
new file mode 100644
index 0000000..5d25f5d
--- /dev/null
+++ b/fs/xfs/xfs_pnfs.c
@@ -0,0 +1,243 @@ 
+/*
+ * Copyright (c) 2014 Christoph Hellwig.
+ */
+#include "xfs.h"
+#include "xfs_format.h"
+#include "xfs_log_format.h"
+#include "xfs_trans_resv.h"
+#include "xfs_sb.h"
+#include "xfs_mount.h"
+#include "xfs_inode.h"
+#include "xfs_trans.h"
+#include "xfs_log.h"
+#include "xfs_bmap.h"
+#include "xfs_bmap_util.h"
+#include "xfs_error.h"
+#include "xfs_iomap.h"
+#include "xfs_shared.h"
+#include "xfs_pnfs.h"
+
+int
+xfs_fs_get_uuid(
+	struct super_block	*sb,
+	u8			*buf,
+	u32			*len,
+	u64			*offset)
+{
+	struct xfs_mount	*mp = XFS_M(sb);
+
+	if (*len < sizeof(uuid_t))
+		return -EINVAL;
+
+	memcpy(buf, &mp->m_sb.sb_uuid, sizeof(uuid_t));
+	*len = sizeof(uuid_t);
+	*offset = offsetof(struct xfs_dsb, sb_uuid);
+	return 0;
+}
+
+static void
+xfs_bmbt_to_iomap(
+	struct xfs_inode	*ip,
+	struct iomap		*iomap,
+	struct xfs_bmbt_irec	*imap)
+{
+	struct xfs_mount	*mp = ip->i_mount;
+
+	if (imap->br_startblock == HOLESTARTBLOCK) {
+		iomap->blkno = -1;
+		iomap->type = IOMAP_HOLE;
+	} else if (imap->br_startblock == DELAYSTARTBLOCK) {
+		iomap->blkno = -1;
+		iomap->type = IOMAP_DELALLOC;
+	} else {
+		iomap->blkno = xfs_fsb_to_db(ip, imap->br_startblock);
+		if (imap->br_state == XFS_EXT_UNWRITTEN)
+			iomap->type = IOMAP_UNWRITTEN;
+		else
+			iomap->type = IOMAP_MAPPED;
+	}
+	iomap->offset = XFS_FSB_TO_B(mp, imap->br_startoff);
+	iomap->length = XFS_FSB_TO_B(mp, imap->br_blockcount);
+}
+
+/*
+ * Get a layout for the pNFS client.
+ */
+int
+xfs_fs_map_blocks(
+	struct inode		*inode,
+	loff_t			offset,
+	u64			length,
+	struct iomap		*iomap,
+	bool			write,
+	u32			*device_generation)
+{
+	struct xfs_inode	*ip = XFS_I(inode);
+	struct xfs_mount	*mp = ip->i_mount;
+	struct xfs_bmbt_irec	imap;
+	xfs_fileoff_t		offset_fsb, end_fsb;
+	loff_t			limit;
+	int			bmapi_flags = XFS_BMAPI_ENTIRE;
+	int			nimaps = 1;
+	uint			lock_flags;
+	int			error = 0;
+
+	if (XFS_FORCED_SHUTDOWN(mp))
+		return -EIO;
+	if (XFS_IS_REALTIME_INODE(ip))
+		return -ENXIO;
+
+	/*
+	 * Lock out any other I/O before we flush and invalidate the pagecache,
+	 * and then hand out a layout to the remote system.  This is very
+	 * similar to direct I/O, except that the synchronization is much more
+	 * complicated.  See the comment near xfs_break_layouts for a detailed
+	 * explanation.
+	 */
+	xfs_ilock(ip, XFS_IOLOCK_EXCL);
+
+	error = -EINVAL;
+	limit = mp->m_super->s_maxbytes;
+	if (!write)
+		limit = max(limit, round_up(i_size_read(inode),
+				     inode->i_sb->s_blocksize));
+	if (offset > limit)
+		goto out_unlock;
+	if (offset > limit - length)
+		length = limit - offset;
+
+	error = filemap_write_and_wait(inode->i_mapping);
+	if (error)
+		goto out_unlock;
+	error = invalidate_inode_pages2(inode->i_mapping);
+	if (WARN_ON_ONCE(error))
+		return error;
+
+	end_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)offset + length);
+	offset_fsb = XFS_B_TO_FSBT(mp, offset);
+
+	lock_flags = xfs_ilock_data_map_shared(ip);
+	error = xfs_bmapi_read(ip, offset_fsb, end_fsb - offset_fsb,
+				&imap, &nimaps, bmapi_flags);
+	xfs_iunlock(ip, lock_flags);
+
+	if (error)
+		goto out_unlock;
+
+	if (write) {
+		enum xfs_prealloc_flags	flags = 0;
+
+		ASSERT(imap.br_startblock != DELAYSTARTBLOCK);
+
+		if (!nimaps || imap.br_startblock == HOLESTARTBLOCK) {
+			error = xfs_iomap_write_direct(ip, offset, length,
+						       &imap, nimaps);
+			if (error)
+				goto out_unlock;
+
+			/*
+			 * Ensure the next transaction is committed
+			 * synchronously so that the blocks allocated and
+			 * handed out to the client are guaranteed to be
+			 * present even after a server crash.
+			 */
+			flags |= XFS_PREALLOC_SET | XFS_PREALLOC_SYNC;
+		}
+
+		error = xfs_update_prealloc_flags(ip, flags);
+		if (error)
+			goto out_unlock;
+	}
+	xfs_iunlock(ip, XFS_IOLOCK_EXCL);
+
+	xfs_bmbt_to_iomap(ip, iomap, &imap);
+	*device_generation = mp->m_generation;
+	return error;
+out_unlock:
+	xfs_iunlock(ip, XFS_IOLOCK_EXCL);
+	return error;
+}
+
+/*
+ * Make sure the blocks described by maps are stable on disk.  This includes
+ * converting any unwritten extents, flushing the disk cache and updating the
+ * time stamps.
+ *
+ * Note that we rely on the caller to always send us a timestamp update so that
+ * we always commit a transaction here.  If that stops being true we will have
+ * to manually flush the cache here similar to what the fsync code path does
+ * for datasyncs on files that have no dirty metadata.
+ */
+int
+xfs_fs_commit_blocks(
+	struct inode		*inode,
+	struct iomap		*maps,
+	int			nr_maps,
+	struct iattr		*iattr)
+{
+	struct xfs_inode	*ip = XFS_I(inode);
+	struct xfs_mount	*mp = ip->i_mount;
+	struct xfs_trans	*tp;
+	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)
+		size = iattr->ia_size;
+
+	for (i = 0; i < nr_maps; i++) {
+		u64 start, length, end;
+
+		start = maps[i].offset;
+		if (start > size)
+			continue;
+
+		end = start + maps[i].length;
+		if (end > size)
+			end = size;
+
+		length = end - start;
+		if (!length)
+			continue;
+	
+		/*
+		 * Make sure reads through the pagecache see the new data.
+		 */
+		error = invalidate_inode_pages2_range(inode->i_mapping,
+					start >> PAGE_CACHE_SHIFT,
+					(end - 1) >> PAGE_CACHE_SHIFT);
+		WARN_ON_ONCE(error);
+
+		error = xfs_iomap_write_unwritten(ip, start, length);
+		if (error)
+			goto out_drop_iolock;
+	}
+
+	tp = xfs_trans_alloc(mp, XFS_TRANS_SETATTR_NOT_SIZE);
+	error = xfs_trans_reserve(tp, &M_RES(mp)->tr_ichange, 0, 0);
+	if (error)
+		goto out_drop_iolock;
+
+	xfs_ilock(ip, XFS_ILOCK_EXCL);
+	xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
+	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
+
+	xfs_setattr_time(ip, iattr);
+	if (iattr->ia_valid & ATTR_SIZE) {
+		if (iattr->ia_size > i_size_read(inode)) {
+			i_size_write(inode, iattr->ia_size);
+			ip->i_d.di_size = iattr->ia_size;
+		}
+	}
+
+	xfs_trans_set_sync(tp);
+	error = xfs_trans_commit(tp, 0);
+
+out_drop_iolock:
+	xfs_iunlock(ip, XFS_IOLOCK_EXCL);
+	return error;
+}
diff --git a/fs/xfs/xfs_pnfs.h b/fs/xfs/xfs_pnfs.h
new file mode 100644
index 0000000..0d91255
--- /dev/null
+++ b/fs/xfs/xfs_pnfs.h
@@ -0,0 +1,11 @@ 
+#ifndef _XFS_PNFS_H
+#define _XFS_PNFS_H 1
+
+#ifdef CONFIG_NFSD_PNFS
+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);
+#endif /* CONFIG_NFSD_PNFS */
+#endif /* _XFS_PNFS_H */