From: Trond Myklebust <trond.myklebust@hammerspace.com>
Date: Fri, 17 Nov 2023 06:25:13 -0500
Subject: [PATCH] pNFS: Fix the pnfs block driver's calculation of layoutget
 size
Git-commit: 8a6291bf3b0eae1bf26621e6419a91682f2d6227
Patch-mainline: v6.8
References: git-fixes

Instead of relying on the value of the 'bytes_left' field, we should
calculate the layout size based on the offset of the request that is
being written out.

Reported-by: Benjamin Coddington <bcodding@redhat.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Fixes: 954998b60caa ("NFS: Fix error handling for O_DIRECT write scheduling")
Reviewed-by: Benjamin Coddington <bcodding@redhat.com>
Tested-by: Benjamin Coddington <bcodding@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Acked-by: NeilBrown <neilb@suse.com>

---
 fs/nfs/blocklayout/blocklayout.c |    5 ++---
 fs/nfs/direct.c                  |    5 +++--
 fs/nfs/internal.h                |    2 +-
 fs/nfs/pnfs.c                    |    3 ++-
 4 files changed, 8 insertions(+), 7 deletions(-)

--- a/fs/nfs/blocklayout/blocklayout.c
+++ b/fs/nfs/blocklayout/blocklayout.c
@@ -847,10 +847,9 @@ bl_pg_init_write(struct nfs_pageio_descr
 	}
 
 	if (pgio->pg_dreq == NULL)
-		wb_size = pnfs_num_cont_bytes(pgio->pg_inode,
-					      req->wb_index);
+		wb_size = pnfs_num_cont_bytes(pgio->pg_inode, req->wb_index);
 	else
-		wb_size = nfs_dreq_bytes_left(pgio->pg_dreq);
+		wb_size = nfs_dreq_bytes_left(pgio->pg_dreq, req_offset(req));
 
 	pnfs_generic_pg_init_write(pgio, req, wb_size);
 }
--- a/fs/nfs/direct.c
+++ b/fs/nfs/direct.c
@@ -267,9 +267,10 @@ static void nfs_direct_req_release(struc
 	kref_put(&dreq->kref, nfs_direct_req_free);
 }
 
-ssize_t nfs_dreq_bytes_left(struct nfs_direct_req *dreq)
+ssize_t nfs_dreq_bytes_left(struct nfs_direct_req *dreq, loff_t offset)
 {
-	return dreq->bytes_left;
+	loff_t start = offset - dreq->io_start;
+	return dreq->max_count - start;
 }
 EXPORT_SYMBOL_GPL(nfs_dreq_bytes_left);
 
--- a/fs/nfs/internal.h
+++ b/fs/nfs/internal.h
@@ -577,7 +577,7 @@ extern int nfs_sillyrename(struct inode
 /* direct.c */
 void nfs_init_cinfo_from_dreq(struct nfs_commit_info *cinfo,
 			      struct nfs_direct_req *dreq);
-extern ssize_t nfs_dreq_bytes_left(struct nfs_direct_req *dreq);
+extern ssize_t nfs_dreq_bytes_left(struct nfs_direct_req *dreq, loff_t offset);
 
 /* nfs4proc.c */
 extern struct nfs_client *nfs4_init_client(struct nfs_client *clp,
--- a/fs/nfs/pnfs.c
+++ b/fs/nfs/pnfs.c
@@ -2173,7 +2173,8 @@ pnfs_generic_pg_init_read(struct nfs_pag
 		if (pgio->pg_dreq == NULL)
 			rd_size = i_size_read(pgio->pg_inode) - req_offset(req);
 		else
-			rd_size = nfs_dreq_bytes_left(pgio->pg_dreq);
+			rd_size = nfs_dreq_bytes_left(pgio->pg_dreq,
+						      req_offset(req));
 
 		pgio->pg_lseg = pnfs_update_layout(pgio->pg_inode,
 						   req->wb_context,