btrfs: subpage: add bitmap for PageChecked flag

Although in btrfs we have very limited usage of PageChecked flag, it's
still some page flag not yet subpage compatible.

Fix it by introducing btrfs_subpage::checked_offset to do the convert.

For most call sites, especially for free-space cache, COW fixup and
btrfs_invalidatepage(), they all work in full page mode anyway.

For other call sites, they work as subpage compatible mode.

Some call sites need extra modification:

- btrfs_drop_pages()
  Needs extra parameter to get the real range we need to clear checked
  flag.

  Also since btrfs_drop_pages() will accept pages beyond the dirtied
  range, update btrfs_subpage_clamp_range() to handle such case
  by setting @len to 0 if the page is beyond target range.

- btrfs_invalidatepage()
  We need to call subpage helper before calling __btrfs_releasepage(),
  or it will trigger ASSERT() as page->private will be cleared.

- btrfs_verify_data_csum()
  In theory we don't need the io_bio->csum check anymore, but it's
  won't hurt.  Just change the comment.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 12 insertions, 5 deletions

diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 6c50561f932f..38e878946761 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -437,9 +437,15 @@ static noinline int btrfs_copy_from_user(loff_t pos, size_t write_bytes,
 /*
  * unlocks pages after btrfs_file_write is done with them
  */
-static void btrfs_drop_pages(struct page **pages, size_t num_pages)
+static void btrfs_drop_pages(struct btrfs_fs_info *fs_info,
+			     struct page **pages, size_t num_pages,
+			     u64 pos, u64 copied)
 {
 	size_t i;
+	u64 block_start = round_down(pos, fs_info->sectorsize);
+	u64 block_len = round_up(pos + copied, fs_info->sectorsize) - block_start;
+
+	ASSERT(block_len <= U32_MAX);
 	for (i = 0; i < num_pages; i++) {
 		/* page checked is some magic around finding pages that
 		 * have been modified without going through btrfs_set_page_dirty
@@ -447,7 +453,8 @@ static void btrfs_drop_pages(struct page **pages, size_t num_pages)
 		 * accessed as prepare_pages should have marked them accessed
 		 * in prepare_pages via find_or_create_page()
 		 */
-		ClearPageChecked(pages[i]);
+		btrfs_page_clamp_clear_checked(fs_info, pages[i], block_start,
+					       block_len);
 		unlock_page(pages[i]);
 		put_page(pages[i]);
 	}
@@ -504,7 +511,7 @@ int btrfs_dirty_pages(struct btrfs_inode *inode, struct page **pages,
 		struct page *p = pages[i];
 
 		btrfs_page_clamp_set_uptodate(fs_info, p, start_pos, num_bytes);
-		ClearPageChecked(p);
+		btrfs_page_clamp_clear_checked(fs_info, p, start_pos, num_bytes);
 		btrfs_page_clamp_set_dirty(fs_info, p, start_pos, num_bytes);
 	}
 
@@ -1843,7 +1850,7 @@ again:
 
 		btrfs_delalloc_release_extents(BTRFS_I(inode), reserve_bytes);
 		if (ret) {
-			btrfs_drop_pages(pages, num_pages);
+			btrfs_drop_pages(fs_info, pages, num_pages, pos, copied);
 			break;
 		}
 
@@ -1851,7 +1858,7 @@ again:
 		if (only_release_metadata)
 			btrfs_check_nocow_unlock(BTRFS_I(inode));
 
-		btrfs_drop_pages(pages, num_pages);
+		btrfs_drop_pages(fs_info, pages, num_pages, pos, copied);
 
 		cond_resched();