[PATCH v13 23/42] btrfs: check if bio spans across an ordered extent

[Naohiro Aota <naohiro.aota@wdc.com>]

From: Johannes Thumshirn <johannes.thumshirn@wdc.com>

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

This commit ensures that constructing bio does not span across an ordered
extent.

Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
---
 fs/btrfs/ctree.h     |  2 ++
 fs/btrfs/extent_io.c |  9 +++++++--
 fs/btrfs/inode.c     | 29 +++++++++++++++++++++++++++++
 3 files changed, 38 insertions(+), 2 deletions(-)

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 4b2e19daed40..1b6f66575471 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -3116,6 +3116,8 @@ 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);
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 9c8faaf260ee..b9fefa624760 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -3097,10 +3097,15 @@ 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;
 }
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index ab97d4349515..286eee122657 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -2217,6 +2217,35 @@ 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)
 {
-- 
2.27.0