afs: afs_fill_page reads too much, or wrong data
afs_fill_page should read the page that is about to be written but
the current implementation has a number of issues. If we aren't
extending the file we always read PAGE_CACHE_SIZE at offset 0. If we
are extending the file we try to read the entire file.
Change afs_fill_page to read PAGE_CACHE_SIZE at the right offset,
clamped to i_size.
While here, avoid calling afs_fill_page when we are doing a
PAGE_CACHE_SIZE write.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/afs/write.c b/fs/afs/write.c
index 789b3af..b806285 100644
--- a/fs/afs/write.c
+++ b/fs/afs/write.c
@@ -84,23 +84,21 @@
* partly or wholly fill a page that's under preparation for writing
*/
static int afs_fill_page(struct afs_vnode *vnode, struct key *key,
- loff_t pos, unsigned len, struct page *page)
+ loff_t pos, struct page *page)
{
loff_t i_size;
- unsigned eof;
int ret;
+ int len;
- _enter(",,%llu,%u", (unsigned long long)pos, len);
-
- ASSERTCMP(len, <=, PAGE_CACHE_SIZE);
+ _enter(",,%llu", (unsigned long long)pos);
i_size = i_size_read(&vnode->vfs_inode);
- if (pos + len > i_size)
- eof = i_size;
+ if (pos + PAGE_CACHE_SIZE > i_size)
+ len = i_size - pos;
else
- eof = PAGE_CACHE_SIZE;
+ len = PAGE_CACHE_SIZE;
- ret = afs_vnode_fetch_data(vnode, key, 0, eof, page);
+ ret = afs_vnode_fetch_data(vnode, key, pos, len, page);
if (ret < 0) {
if (ret == -ENOENT) {
_debug("got NOENT from server"
@@ -153,9 +151,8 @@
*pagep = page;
/* page won't leak in error case: it eventually gets cleaned off LRU */
- if (!PageUptodate(page)) {
- _debug("not up to date");
- ret = afs_fill_page(vnode, key, pos, len, page);
+ if (!PageUptodate(page) && len != PAGE_CACHE_SIZE) {
+ ret = afs_fill_page(vnode, key, index << PAGE_CACHE_SHIFT, page);
if (ret < 0) {
kfree(candidate);
_leave(" = %d [prep]", ret);