btrfs: zoned: check if bio spans across an ordered extent

To ensure that an ordered extent maps to a contiguous region on disk, we
need to maintain a "one bio == one ordered extent" rule.

Ensure that constructing bio does not span more than an ordered extent.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/ctree.h

@@ -3120,6 +3120,8 @@ void btrfs_split_delalloc_extent(struct inode *inode,
 				 struct extent_state *orig, u64 split);
 int btrfs_bio_fits_in_stripe(struct page *page, size_t size, struct bio *bio,
 			     unsigned long bio_flags);
+bool btrfs_bio_fits_in_ordered_extent(struct page *page, struct bio *bio,
+				      unsigned int size);
 void btrfs_set_range_writeback(struct extent_io_tree *tree, u64 start, u64 end);
 vm_fault_t btrfs_page_mkwrite(struct vm_fault *vmf);
 int btrfs_readpage(struct file *file, struct page *page);

fs/btrfs/extent_io.c

@@ -3124,10 +3124,15 @@ static bool btrfs_bio_add_page(struct bio *bio, struct page *page,
 	if (btrfs_bio_fits_in_stripe(page, size, bio, bio_flags))
 		return false;
 
-	if (bio_op(bio) == REQ_OP_ZONE_APPEND)
+	if (bio_op(bio) == REQ_OP_ZONE_APPEND) {
+		struct page *first_page = bio_first_bvec_all(bio)->bv_page;
+
+		if (!btrfs_bio_fits_in_ordered_extent(first_page, bio, size))
+			return false;
 		ret = bio_add_zone_append_page(bio, page, size, pg_offset);
-	else
+	} else {
 		ret = bio_add_page(bio, page, size, pg_offset);
+	}
 
 	return ret == size;
 }

fs/btrfs/inode.c

@@ -2215,6 +2215,33 @@ static blk_status_t btrfs_submit_bio_start(struct inode *inode, struct bio *bio,
 	return btrfs_csum_one_bio(BTRFS_I(inode), bio, 0, 0);
 }
 
+bool btrfs_bio_fits_in_ordered_extent(struct page *page, struct bio *bio,
+				      unsigned int size)
+{
+	struct btrfs_inode *inode = BTRFS_I(page->mapping->host);
+	struct btrfs_fs_info *fs_info = inode->root->fs_info;
+	struct btrfs_ordered_extent *ordered;
+	u64 len = bio->bi_iter.bi_size + size;
+	bool ret = true;
+
+	ASSERT(btrfs_is_zoned(fs_info));
+	ASSERT(fs_info->max_zone_append_size > 0);
+	ASSERT(bio_op(bio) == REQ_OP_ZONE_APPEND);
+
+	/* Ordered extent not yet created, so we're good */
+	ordered = btrfs_lookup_ordered_extent(inode, page_offset(page));
+	if (!ordered)
+		return ret;
+
+	if ((bio->bi_iter.bi_sector << SECTOR_SHIFT) + len >
+	    ordered->disk_bytenr + ordered->disk_num_bytes)
+		ret = false;
+
+	btrfs_put_ordered_extent(ordered);
+
+	return ret;
+}
+
 static blk_status_t extract_ordered_extent(struct btrfs_inode *inode,
 					   struct bio *bio, loff_t file_offset)
 {