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 <[email protected]> --- 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 3158461ebf4c..3bd4b99897d6 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -5146,9 +5146,14 @@ 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]); + if (ret < 0) + goto err; } set_extent_buffer_uptodate(eb); btrfs_set_header_nritems(eb, 0); @@ -5156,8 +5161,10 @@ 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; } -- 2.29.2
