Btrfs: handle no memory properly in prepare_pages

Instead of doing a BUG_ON(1) in prepare_pages if grab_cache_page() fails, just
loop through the pages we've already grabbed and unlock and release them, then
return -ENOMEM like we should.  Thanks,

Signed-off-by: Josef Bacik <josef@redhat.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 65b2424a4116b37d5c4bf8e2fd5fc724ceb581ca..9e097fbfc78d395dca4e461f5a054135aa4e1ba3 100644 (file)
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -792,8 +792,12 @@ again:
        for (i = 0; i < num_pages; i++) {
                pages[i] = grab_cache_page(inode->i_mapping, index + i);
                if (!pages[i]) {
-                       err = -ENOMEM;
-                       BUG_ON(1);
+                       int c;
+                       for (c = i - 1; c >= 0; c--) {
+                               unlock_page(pages[c]);
+                               page_cache_release(pages[c]);
+                       }
+                       return -ENOMEM;
                }
                wait_on_page_writeback(pages[i]);
        }