[PATCH v4 09/21] fs: afs: revert mmap_prepare() change

[Lorenzo Stoakes (Oracle)]

Partially reverts commit 9d5403b1036c ("fs: convert most other
generic_file_*mmap() users to .mmap_prepare()").

This is because the .mmap invocation establishes a refcount, but
.mmap_prepare is called at a point where a merge or an allocation failure
might happen after the call, which would leak the refcount increment.

Functionality is being added to permit the use of .mmap_prepare in this
case, but in the interim, we need to fix this.

Fixes: 9d5403b1036c ("fs: convert most other generic_file_*mmap() users to .mmap_prepare()")
Cc: <stable at vger.kernel.org>
Signed-off-by: Lorenzo Stoakes (Oracle) <ljs at kernel.org>
---
 fs/afs/file.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/fs/afs/file.c b/fs/afs/file.c
index f609366fd2ac..74d04af51ff4 100644
--- a/fs/afs/file.c
+++ b/fs/afs/file.c
@@ -19,7 +19,7 @@
 #include <trace/events/netfs.h>
 #include "internal.h"
 
-static int afs_file_mmap_prepare(struct vm_area_desc *desc);
+static int afs_file_mmap(struct file *file, struct vm_area_struct *vma);
 
 static ssize_t afs_file_read_iter(struct kiocb *iocb, struct iov_iter *iter);
 static ssize_t afs_file_splice_read(struct file *in, loff_t *ppos,
@@ -35,7 +35,7 @@ const struct file_operations afs_file_operations = {
 	.llseek		= generic_file_llseek,
 	.read_iter	= afs_file_read_iter,
 	.write_iter	= netfs_file_write_iter,
-	.mmap_prepare	= afs_file_mmap_prepare,
+	.mmap		= afs_file_mmap,
 	.splice_read	= afs_file_splice_read,
 	.splice_write	= iter_file_splice_write,
 	.fsync		= afs_fsync,
@@ -492,16 +492,16 @@ static void afs_drop_open_mmap(struct afs_vnode *vnode)
 /*
  * Handle setting up a memory mapping on an AFS file.
  */
-static int afs_file_mmap_prepare(struct vm_area_desc *desc)
+static int afs_file_mmap(struct file *file, struct vm_area_struct *vma)
 {
-	struct afs_vnode *vnode = AFS_FS_I(file_inode(desc->file));
+	struct afs_vnode *vnode = AFS_FS_I(file_inode(file));
 	int ret;
 
 	afs_add_open_mmap(vnode);
 
-	ret = generic_file_mmap_prepare(desc);
+	ret = generic_file_mmap(file, vma);
 	if (ret == 0)
-		desc->vm_ops = &afs_vm_ops;
+		vma->vm_ops = &afs_vm_ops;
 	else
 		afs_drop_open_mmap(vnode);
 	return ret;
-- 
2.53.0