[RFC PATCH v1 04/10] KVM: guest_memfd: Implement evict_inode for guest_memfd

[Ackerley Tng <ackerleytng@google.com>]

In a later patch, guest_memfd will be using a custom truncation
routine. This is a preparatory patch, which implements .evict_inode for
guest_memfd, but just performs exactly what would have been done if
.evict_inode were not implemented.

No functional change intended.

Signed-off-by: Ackerley Tng <ackerleytng@google.com>
---
 virt/kvm/guest_memfd.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c
index 2488d7b8f2b0d..57dec458bfa77 100644
--- a/virt/kvm/guest_memfd.c
+++ b/virt/kvm/guest_memfd.c
@@ -978,11 +978,23 @@ static void kvm_gmem_free_inode(struct inode *inode)
 	kmem_cache_free(kvm_gmem_inode_cachep, GMEM_I(inode));
 }
 
+static void kvm_gmem_evict_inode(struct inode *inode)
+{
+	struct address_space *mapping = inode->i_mapping;
+
+	truncate_inode_pages_final_prepare(mapping);
+
+	truncate_inode_pages_range(mapping, 0, inode->i_size);
+
+	clear_inode(inode);
+}
+
 static const struct super_operations kvm_gmem_super_operations = {
 	.statfs		= simple_statfs,
 	.alloc_inode	= kvm_gmem_alloc_inode,
 	.destroy_inode	= kvm_gmem_destroy_inode,
 	.free_inode	= kvm_gmem_free_inode,
+	.evict_inode	= kvm_gmem_evict_inode,
 };
 
 static int kvm_gmem_init_fs_context(struct fs_context *fc)
-- 
2.53.0.345.g96ddfc5eaa-goog