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>

diff --git a/fs/afs/write.c b/fs/afs/write.c
index fdb9d60..11066a3 100644 (file)
--- 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)