[PATCH 6/7] exportfs: return a device index from ->map_blocks

[Christoph Hellwig <hch@lst.de>]

Allow file systems to return a device index from ->map_block that
indicates which device the layout is placed on.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/nfsd/blocklayout.c          | 7 +++++--
 fs/xfs/xfs_pnfs.c              | 3 +++
 include/linux/exportfs_block.h | 2 +-
 3 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/fs/nfsd/blocklayout.c b/fs/nfsd/blocklayout.c
index fb13f86f8eb5..636ccefe1959 100644
--- a/fs/nfsd/blocklayout.c
+++ b/fs/nfsd/blocklayout.c
@@ -30,10 +30,12 @@ nfsd4_block_map_extent(struct inode *inode, const struct svc_fh *fhp,
 	struct super_block *sb = inode->i_sb;
 	struct iomap iomap;
 	u32 device_generation = 0;
+	u32 dev_idx = 0;
 	int error;
 
 	error = sb->s_export_op->block_ops->map_blocks(inode, offset, length,
-			&iomap, iomode != IOMODE_READ, &device_generation);
+			&iomap, iomode != IOMODE_READ, &dev_idx,
+			&device_generation);
 	if (error) {
 		if (error == -ENXIO)
 			return nfserr_layoutunavailable;
@@ -75,7 +77,8 @@ nfsd4_block_map_extent(struct inode *inode, const struct svc_fh *fhp,
 		return nfserr_layoutunavailable;
 	}
 
-	error = nfsd4_set_deviceid(&bex->vol_id, fhp, 0, device_generation);
+	error = nfsd4_set_deviceid(&bex->vol_id, fhp, dev_idx,
+			device_generation);
 	if (error)
 		return nfserrno(error);
 
diff --git a/fs/xfs/xfs_pnfs.c b/fs/xfs/xfs_pnfs.c
index acefa0b99f53..7ef5a3f522f6 100644
--- a/fs/xfs/xfs_pnfs.c
+++ b/fs/xfs/xfs_pnfs.c
@@ -123,6 +123,7 @@ xfs_fs_map_blocks(
 	u64			length,
 	struct iomap		*iomap,
 	bool			write,
+	u32			*dev_idx,
 	u32			*device_generation)
 {
 	struct xfs_inode	*ip = XFS_I(inode);
@@ -139,6 +140,8 @@ xfs_fs_map_blocks(
 	if (xfs_is_shutdown(mp))
 		return -EIO;
 
+	*dev_idx = 0;
+
 	/*
 	 * We can't export inodes residing on the realtime device.  The realtime
 	 * device doesn't have a UUID to identify it, so the client has no way
diff --git a/include/linux/exportfs_block.h b/include/linux/exportfs_block.h
index a3f4054784e3..ec2f846c6b08 100644
--- a/include/linux/exportfs_block.h
+++ b/include/linux/exportfs_block.h
@@ -52,7 +52,7 @@ struct exportfs_block_ops {
 	 * 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,
+			struct iomap *iomap, bool write, u32 *dev_idx,
 			u32 *device_generation);
 
 	/*
-- 
2.47.3