Extract a version of kvm_gmem_punch_hole() that expects the
caller to take the filemap invalidate_lock.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 virt/kvm/guest_memfd.c | 25 +++++++++++++++----------
 1 file changed, 15 insertions(+), 10 deletions(-)

diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c
index a537a7e63ab5..51c99667690a 100644
--- a/virt/kvm/guest_memfd.c
+++ b/virt/kvm/guest_memfd.c
@@ -152,19 +152,12 @@ static void kvm_gmem_invalidate_end(struct kvm_gmem *gmem, pgoff_t start,
 	}
 }
 
-static long kvm_gmem_punch_hole(struct inode *inode, loff_t offset, loff_t len)
+static long __kvm_gmem_punch_hole(struct inode *inode, loff_t offset, loff_t len)
 {
 	struct list_head *gmem_list = &inode->i_mapping->i_private_list;
 	pgoff_t start = offset >> PAGE_SHIFT;
 	pgoff_t end = (offset + len) >> PAGE_SHIFT;
 	struct kvm_gmem *gmem;
-
-	/*
-	 * Bindings must be stable across invalidation to ensure the start+end
-	 * are balanced.
-	 */
-	filemap_invalidate_lock(inode->i_mapping);
-
 	list_for_each_entry(gmem, gmem_list, entry)
 		kvm_gmem_invalidate_begin(gmem, start, end);
 
@@ -173,11 +166,23 @@ static long kvm_gmem_punch_hole(struct inode *inode, loff_t offset, loff_t len)
 	list_for_each_entry(gmem, gmem_list, entry)
 		kvm_gmem_invalidate_end(gmem, start, end);
 
-	filemap_invalidate_unlock(inode->i_mapping);
-
 	return 0;
 }
 
+static long kvm_gmem_punch_hole(struct inode *inode, loff_t offset, loff_t len)
+{
+	int r;
+
+	/*
+	 * Bindings must be stable across invalidation to ensure the start+end
+	 * are balanced.
+	 */
+	filemap_invalidate_lock(inode->i_mapping);
+	r = __kvm_gmem_punch_hole(inode, offset, len);
+	filemap_invalidate_unlock(inode->i_mapping);
+	return r;
+}
+
 static long kvm_gmem_allocate(struct inode *inode, loff_t offset, loff_t len)
 {
 	struct address_space *mapping = inode->i_mapping;
-- 
2.43.0