[05/11] btrfs: simplify btrfs_extract_ordered_extent

Commit Message

Christoph Hellwig March 28, 2023, 5:19 a.m. UTC

btrfs_extract_ordered_extent is always used to split an ordered_extent
and extent_map into two parts, so it doesn't need to deal with a three
way split.

Simplify it by only allowing for a single split point, and always split
out the beginning of the extent, as that is what we'll later need to
be able to hold on to a reference to the original ordered_extent that
the first part is split off for submission.

Signed-off-by: Christoph Hellwig <[e-mail]>
Tested-by: Johannes Thumshirn <[e-mail]>
---
 fs/btrfs/inode.c | 29 +++++++++++++----------------
 1 file changed, 13 insertions(+), 16 deletions(-)

Comments

David Sterba March 28, 2023, 5:53 p.m. UTC | #1

On Tue, Mar 28, 2023 at 02:19:51PM +0900, Christoph Hellwig wrote:

Subject: Re: [PATCH 05/11] btrfs: simplify btrfs_extract_ordered_extent

Please don't write subjects like 'simplify function'. There are many
ways how a function can be simplified or cleaned up and with so many
patches being merged it's obscuring what is actually being changed.  I'm
editing where I think the subject does not match and I won't bother
anybody if it's rare but within this series 3 out of 6 have such
subject. The changelog usually has that so the subject should state what
or how things are simplified.

Patch

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 5013d1b0b00e29..428fa99711def1 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -2632,39 +2632,36 @@  blk_status_t btrfs_extract_ordered_extent(struct btrfs_bio *bbio)
 	u64 len = bbio->bio.bi_iter.bi_size;
 	struct btrfs_inode *inode = bbio->inode;
 	struct btrfs_ordered_extent *ordered;
-	u64 file_len;
-	u64 end = start + len;
-	u64 ordered_end;
-	u64 pre, post;
+	u64 ordered_len;
 	int ret = 0;
 
 	ordered = btrfs_lookup_ordered_extent(inode, bbio->file_offset);
 	if (WARN_ON_ONCE(!ordered))
 		return BLK_STS_IOERR;
+	ordered_len = ordered->num_bytes;
 
-	/* No need to split */
-	if (ordered->disk_num_bytes == len)
+	/* Must always be called for the beginning of an ordered extent. */
+	if (WARN_ON_ONCE(start != ordered->disk_bytenr)) {
+		ret = -EINVAL;
 		goto out;
+	}
 
-	ordered_end = ordered->disk_bytenr + ordered->disk_num_bytes;
-	/* bio must be in one ordered extent */
-	if (WARN_ON_ONCE(start < ordered->disk_bytenr || end > ordered_end)) {
+	/* The bio must be entirely covered by the ordered extent */
+	if (WARN_ON_ONCE(len > ordered_len)) {
 		ret = -EINVAL;
 		goto out;
 	}
 
-	file_len = ordered->num_bytes;
-	pre = start - ordered->disk_bytenr;
-	post = ordered_end - end;
+	/* No need to split if the ordered extent covers the entire bio */
+	if (ordered->disk_num_bytes == len)
+		goto out;
 
-	ret = btrfs_split_ordered_extent(ordered, pre, post);
+	ret = btrfs_split_ordered_extent(ordered, len, 0);
 	if (ret)
 		goto out;
-	ret = split_zoned_em(inode, bbio->file_offset, file_len, pre, post);
-
+	ret = split_zoned_em(inode, bbio->file_offset, ordered_len, len, 0);
 out:
 	btrfs_put_ordered_extent(ordered);
-
 	return errno_to_blk_status(ret);
 }