afs: Fix page leak in afs_write_begin()

afs_write_begin() leaks a ref and a lock on a page if afs_fill_page()
fails.  Fix the leak by unlocking and releasing the page in the error path.

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

diff --git a/fs/afs/write.c b/fs/afs/write.c
index f1450ea094068535802b4a409df2b7b0199974ea..6e13e96c3db0d3371e46afdaffd8ee8336832a57 100644 (file)
--- a/fs/afs/write.c
+++ b/fs/afs/write.c
@@ -154,12 +154,12 @@ int afs_write_begin(struct file *file, struct address_space *mapping,
                kfree(candidate);
                return -ENOMEM;
        }
-       *pagep = page;
-       /* page won't leak in error case: it eventually gets cleaned off LRU */
 
        if (!PageUptodate(page) && len != PAGE_SIZE) {
                ret = afs_fill_page(vnode, key, pos & PAGE_MASK, PAGE_SIZE, page);
                if (ret < 0) {
+                       unlock_page(page);
+                       put_page(page);
                        kfree(candidate);
                        _leave(" = %d [prep]", ret);
                        return ret;
@@ -167,6 +167,9 @@ int afs_write_begin(struct file *file, struct address_space *mapping,
                SetPageUptodate(page);
        }
 
+       /* page won't leak in error case: it eventually gets cleaned off LRU */
+       *pagep = page;
+
 try_again:
        spin_lock(&vnode->writeback_lock);