From: Qu Wenruo Date: Wed, 2 Dec 2020 06:48:03 +0000 (+0800) Subject: btrfs: update num_extent_pages to support subpage sized extent buffer X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=4a3dc93843dd6ee17c68231d6a90c76231cb65fc;p=linux.git btrfs: update num_extent_pages to support subpage sized extent buffer For subpage sized extent buffer, we have ensured no extent buffer will cross page boundary, thus we would only need one page for any extent buffer. Update function num_extent_pages to handle such case. Now num_extent_pages() returns 1 for subpage sized extent buffer. Reviewed-by: Nikolay Borisov Signed-off-by: Qu Wenruo Reviewed-by: David Sterba Signed-off-by: David Sterba --- diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h index 77f2211550e3b..19221095c6358 100644 --- a/fs/btrfs/extent_io.h +++ b/fs/btrfs/extent_io.h @@ -203,8 +203,14 @@ void btrfs_readahead_node_child(struct extent_buffer *node, int slot); static inline int num_extent_pages(const struct extent_buffer *eb) { - return (round_up(eb->start + eb->len, PAGE_SIZE) >> PAGE_SHIFT) - - (eb->start >> PAGE_SHIFT); + /* + * For sectorsize == PAGE_SIZE case, since nodesize is always aligned to + * sectorsize, it's just eb->len >> PAGE_SHIFT. + * + * For sectorsize < PAGE_SIZE case, we could have nodesize < PAGE_SIZE, + * thus have to ensure we get at least one page. + */ + return (eb->len >> PAGE_SHIFT) ?: 1; } static inline int extent_buffer_uptodate(const struct extent_buffer *eb)