Commit 09bc1f0f authored by Qu Wenruo's avatar Qu Wenruo Committed by David Sterba
Browse files

btrfs: attach private to dummy extent buffer pages 



There are locations where we allocate dummy extent buffers for temporary
usage, like in tree_mod_log_rewind() or get_old_root().

These dummy extent buffers will be handled by the same eb accessors, and
if they don't have page::private subpage eb accessors could fail.

To address such problems, make __alloc_dummy_extent_buffer() attach
page private for dummy extent buffers too.

Reviewed-by: default avatarJosef Bacik <josef@toxicpanda.com>
Signed-off-by: default avatarQu Wenruo <wqu@suse.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 8ff8466d

fs/btrfs/extent_io.c

+8 −1
Original line number Diff line number Diff line
@@ -5185,9 +5185,14 @@ struct extent_buffer *__alloc_dummy_extent_buffer(struct btrfs_fs_info *fs_info, 


	num_pages = num_extent_pages(eb);

	for (i = 0; i < num_pages; i++) {

		int ret;



		eb->pages[i] = alloc_page(GFP_NOFS);

		if (!eb->pages[i])

			goto err;

		ret = attach_extent_buffer_page(eb, eb->pages[i], NULL);

		if (ret < 0)

			goto err;

	}

	set_extent_buffer_uptodate(eb);

	btrfs_set_header_nritems(eb, 0);
@@ -5195,8 +5200,10 @@ struct extent_buffer *__alloc_dummy_extent_buffer(struct btrfs_fs_info *fs_info, 


	return eb;

err:

	for (; i > 0; i--)

	for (; i > 0; i--) {

		detach_extent_buffer_page(eb, eb->pages[i - 1]);

		__free_page(eb->pages[i - 1]);

	}

	__free_extent_buffer(eb);

	return NULL;

}