Btrfs: fix page reading in extent_same ioctl leading to csum errors

[firefly-linux-kernel-4.4.55.git] / fs / btrfs / ioctl.c

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index e225a615ad03e6da9b88f2799096a6784476e5c3..08fd3f0f34fd086d5faaa257608e0be5b8020c9b 100644 (file)
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -2782,21 +2782,27 @@ out:
 static struct page *extent_same_get_page(struct inode *inode, pgoff_t index)
 {
        struct page *page;
-       struct extent_io_tree *tree = &BTRFS_I(inode)->io_tree;
 
        page = grab_cache_page(inode->i_mapping, index);
        if (!page)
-               return NULL;
+               return ERR_PTR(-ENOMEM);
 
        if (!PageUptodate(page)) {
-               if (extent_read_full_page_nolock(tree, page, btrfs_get_extent,
-                                                0))
-                       return NULL;
+               int ret;
+
+               ret = btrfs_readpage(NULL, page);
+               if (ret)
+                       return ERR_PTR(ret);
                lock_page(page);
                if (!PageUptodate(page)) {
                        unlock_page(page);
                        page_cache_release(page);
-                       return NULL;
+                       return ERR_PTR(-EIO);
+               }
+               if (page->mapping != inode->i_mapping) {
+                       unlock_page(page);
+                       page_cache_release(page);
+                       return ERR_PTR(-EAGAIN);
                }
        }
 
@@ -2810,9 +2816,16 @@ static int gather_extent_pages(struct inode *inode, struct page **pages,
        pgoff_t index = off >> PAGE_CACHE_SHIFT;
 
        for (i = 0; i < num_pages; i++) {
+again:
                pages[i] = extent_same_get_page(inode, index + i);
-               if (!pages[i])
-                       return -ENOMEM;
+               if (IS_ERR(pages[i])) {
+                       int err = PTR_ERR(pages[i]);
+
+                       if (err == -EAGAIN)
+                               goto again;
+                       pages[i] = NULL;
+                       return err;
+               }
        }
        return 0;
 }