afs: Don't invoke the server to read data beyond EOF

When writing a new page, clear space in the page rather than attempting to
load it from the server if the space is beyond the EOF.

Signed-off-by: David Howells <dhowells@redhat.com>

1 files changed, 11 insertions, 0 deletions

diff --git a/fs/afs/write.c b/fs/afs/write.c
index fdb9d6024126..11066a3248ba 100644
--- a/fs/afs/write.c
+++ b/fs/afs/write.c
@@ -33,10 +33,21 @@ static int afs_fill_page(struct afs_vnode *vnode, struct key *key,
                          loff_t pos, unsigned int len, struct page *page)
 {
         struct afs_read *req;
+        size_t p;
+        void *data;
         int ret;
 
         _enter(",,%llu", (unsigned long long)pos);
 
+        if (pos >= vnode->vfs_inode.i_size) {
+                p = pos & ~PAGE_MASK;
+                ASSERTCMP(p + len, <=, PAGE_SIZE);
+                data = kmap(page);
+                memset(data + p, 0, len);
+                kunmap(page);
+                return 0;
+        }
+
         req = kzalloc(sizeof(struct afs_read) + sizeof(struct page *),
                       GFP_KERNEL);
         if (!req)