From: Trond Myklebust <trond.myklebust@hammerspace.com>
Date: Wed, 14 Apr 2021 10:10:09 -0400
Subject: [PATCH] NFSv42: Copy offload should update the file size when
 appropriate
Git-commit: 94d202d5ca39d0eb757d16ef2624b013fb64f64d
Patch-mainline: v5.13
References: git-fixes

If the result of a copy offload or clone operation is to grow the
destination file size, then we should update it. The reason is that when
a client holds a delegation, it is authoritative for the file size.

Fixes: 16abd2a0c124 ("NFSv4.2: fix client's attribute cache management for copy_file_range")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Acked-by: NeilBrown <neilb@suse.com>

---
 fs/nfs/nfs42proc.c |   37 +++++++++++++++++++++++++++++--------
 1 file changed, 29 insertions(+), 8 deletions(-)

--- a/fs/nfs/nfs42proc.c
+++ b/fs/nfs/nfs42proc.c
@@ -129,6 +129,30 @@ out_unlock:
 	return err;
 }
 
+/**
+ * nfs42_copy_dest_done - perform inode cache updates after clone/copy offload
+ * @inode: pointer to destination inode
+ * @pos: destination offset
+ * @len: copy length
+ *
+ * Punch a hole in the inode page cache, so that the NFS client will
+ * know to retrieve new data.
+ * Update the file size if necessary, and then mark the inode as having
+ * invalid cached values for change attribute, ctime, mtime and space used.
+ */
+static void nfs42_copy_dest_done(struct inode *inode, loff_t pos, loff_t len)
+{
+	loff_t newsize = pos + len;
+	loff_t end = newsize - 1;
+
+	truncate_pagecache_range(inode, pos, end);
+	spin_lock(&inode->i_lock);
+	if (newsize > i_size_read(inode))
+		i_size_write(inode, newsize);
+	NFS_I(inode)->cache_validity |= NFS_INO_INVALID_ATTR;
+	spin_unlock(&inode->i_lock);
+}
+
 static ssize_t _nfs42_proc_copy(struct file *src,
 				struct nfs_lock_context *src_lock,
 				struct file *dst,
@@ -183,13 +207,8 @@ static ssize_t _nfs42_proc_copy(struct f
 		goto out;
 	}
 
-	truncate_pagecache_range(dst_inode, pos_dst,
-				 pos_dst + res->write_res.count);
-	spin_lock(&dst_inode->i_lock);
-	NFS_I(dst_inode)->cache_validity |= (NFS_INO_REVAL_PAGECACHE |
-			NFS_INO_REVAL_FORCED |
-			NFS_INO_INVALID_ATTR | NFS_INO_INVALID_DATA);
-	spin_unlock(&dst_inode->i_lock);
+	nfs42_copy_dest_done(dst_inode, pos_dst, res->write_res.count);
+
 	spin_lock(&file_inode(src)->i_lock);
 	NFS_I(file_inode(src))->cache_validity |= (NFS_INO_REVAL_PAGECACHE |
 			NFS_INO_REVAL_FORCED | NFS_INO_INVALID_ATIME);
@@ -517,8 +536,10 @@ static int _nfs42_proc_clone(struct rpc_
 
 	status = nfs4_call_sync(server->client, server, msg,
 				&args.seq_args, &res.seq_res, 0);
-	if (status == 0)
+	if (status == 0) {
+		nfs42_copy_dest_done(dst_inode, dst_offset, count);
 		status = nfs_post_op_update_inode(dst_inode, res.dst_fattr);
+	}
 
 	kfree(res.dst_fattr);
 	return status;