[PATCH v4 07/18] btrfs: attach private to dummy extent buffer pages
From: Qu Wenruo <hidden>
Date: 2021-01-16 07:17:30
Subsystem:
btrfs file system, filesystems (vfs and infrastructure), the rest · Maintainers:
Chris Mason, David Sterba, Alexander Viro, Christian Brauner, Linus Torvalds
Even for regular btrfs, there are locations where we allocate dummy extent buffers for temporary usage. Like tree_mod_log_rewind() and get_old_root(). Those dummy extent buffers will be handled by the same eb accessors, and if they don't have page::private subpage eb accessors can fail. To address such problems, make __alloc_dummy_extent_buffer() to attach page private for dummy extent buffers too. Signed-off-by: Qu Wenruo <redacted> --- fs/btrfs/extent_io.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index fb800f237099..7f94f00936d7 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c@@ -5204,9 +5204,14 @@ 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);
@@ -5214,8 +5219,10 @@ 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; }
--
2.30.0