No changes in functionality. Split the proc_layoutget function to
create a helper function that maps single extent to the requested
range. This helper function is then used to implement support for
multiple extents per LAYOUTGET.

Signed-off-by: Sergey Bashirov <sergeybashirov@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
 fs/nfsd/blocklayout.c | 115 ++++++++++++++++++++++++------------------
 1 file changed, 66 insertions(+), 49 deletions(-)

diff --git a/fs/nfsd/blocklayout.c b/fs/nfsd/blocklayout.c
index 425648565ab2..35a95501db63 100644
--- a/fs/nfsd/blocklayout.c
+++ b/fs/nfsd/blocklayout.c
@@ -17,68 +17,44 @@
 #define NFSDDBG_FACILITY	NFSDDBG_PNFS
 
 
+/*
+ * Get an extent from the file system that starts at offset or below
+ * and may be shorter than the requested length.
+ */
 static __be32
-nfsd4_block_proc_layoutget(struct svc_rqst *rqstp, struct inode *inode,
-		const struct svc_fh *fhp, struct nfsd4_layoutget *args)
+nfsd4_block_map_extent(struct inode *inode, const struct svc_fh *fhp,
+		u64 offset, u64 length, u32 iomode, u64 minlength,
+		struct pnfs_block_extent *bex)
 {
-	struct nfsd4_layout_seg *seg = &args->lg_seg;
 	struct super_block *sb = inode->i_sb;
-	u64 length;
-	u32 block_size = i_blocksize(inode);
-	struct pnfs_block_extent *bex;
 	struct iomap iomap;
 	u32 device_generation = 0;
 	int error;
 
-	if (locks_in_grace(SVC_NET(rqstp)))
-		return nfserr_grace;
-
-	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);
+	error = sb->s_export_op->map_blocks(inode, offset, length, &iomap,
+			iomode != IOMODE_READ, &device_generation);
 	if (error) {
 		if (error == -ENXIO)
-			goto out_layoutunavailable;
-		goto out_error;
-	}
-
-	length = iomap.offset + iomap.length - seg->offset;
-	if (length < args->lg_minlength) {
-		dprintk("pnfsd: extent smaller than minlength\n");
-		goto out_layoutunavailable;
+			return nfserr_layoutunavailable;
+		return nfserrno(error);
 	}
 
 	switch (iomap.type) {
 	case IOMAP_MAPPED:
-		if (seg->iomode == IOMODE_READ)
+		if (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) {
+		if (iomode & IOMODE_RW) {
 			/*
 			 * Crack monkey special case from section 2.3.1.
 			 */
-			if (args->lg_minlength == 0) {
+			if (minlength == 0) {
 				dprintk("pnfsd: no soup for you!\n");
-				goto out_layoutunavailable;
+				return nfserr_layoutunavailable;
 			}
 
 			bex->es = PNFS_BLOCK_INVALID_DATA;
@@ -87,7 +63,7 @@ nfsd4_block_proc_layoutget(struct svc_rqst *rqstp, struct inode *inode,
 		}
 		fallthrough;
 	case IOMAP_HOLE:
-		if (seg->iomode == IOMODE_READ) {
+		if (iomode == IOMODE_READ) {
 			bex->es = PNFS_BLOCK_NONE_DATA;
 			break;
 		}
@@ -95,27 +71,68 @@ nfsd4_block_proc_layoutget(struct svc_rqst *rqstp, struct inode *inode,
 	case IOMAP_DELALLOC:
 	default:
 		WARN(1, "pnfsd: filesystem returned %d extent\n", iomap.type);
-		goto out_layoutunavailable;
+		return nfserr_layoutunavailable;
 	}
 
 	error = nfsd4_set_deviceid(&bex->vol_id, fhp, device_generation);
 	if (error)
-		goto out_error;
+		return nfserrno(error);
+
 	bex->foff = iomap.offset;
 	bex->len = iomap.length;
+	return nfs_ok;
+}
+
+static __be32
+nfsd4_block_proc_layoutget(struct svc_rqst *rqstp, struct inode *inode,
+		const struct svc_fh *fhp, struct nfsd4_layoutget *args)
+{
+	struct nfsd4_layout_seg *seg = &args->lg_seg;
+	struct pnfs_block_extent *bex;
+	u64 length;
+	u32 block_size = i_blocksize(inode);
+	__be32 nfserr;
+
+	if (locks_in_grace(SVC_NET(rqstp)))
+		return nfserr_grace;
 
-	seg->offset = iomap.offset;
-	seg->length = iomap.length;
+	nfserr = nfserr_layoutunavailable;
+	if (seg->offset & (block_size - 1)) {
+		dprintk("pnfsd: I/O misaligned\n");
+		goto out_error;
+	}
+
+	/*
+	 * Some clients barf on non-zero block numbers for NONE or INVALID
+	 * layouts, so make sure to zero the whole structure.
+	 */
+	nfserr = nfserrno(-ENOMEM);
+	bex = kzalloc(sizeof(*bex), GFP_KERNEL);
+	if (!bex)
+		goto out_error;
+	args->lg_content = bex;
+
+	nfserr = nfsd4_block_map_extent(inode, fhp, seg->offset, seg->length,
+			seg->iomode, args->lg_minlength, bex);
+	if (nfserr != nfs_ok)
+		goto out_error;
+
+	nfserr = nfserr_layoutunavailable;
+	length = bex->foff + bex->len - seg->offset;
+	if (length < args->lg_minlength) {
+		dprintk("pnfsd: extent smaller than minlength\n");
+		goto out_error;
+	}
+
+	seg->offset = bex->foff;
+	seg->length = bex->len;
 
 	dprintk("GET: 0x%llx:0x%llx %d\n", bex->foff, bex->len, bex->es);
-	return 0;
+	return nfs_ok;
 
 out_error:
 	seg->length = 0;
-	return nfserrno(error);
-out_layoutunavailable:
-	seg->length = 0;
-	return nfserr_layoutunavailable;
+	return nfserr;
 }
 
 static __be32
-- 
2.43.0