From 2d974619a77f106f3d1341686dea95c0eaad601f Mon Sep 17 00:00:00 2001

From: Qu Wenruo <wqu@suse.com>

Date: Wed, 23 Oct 2019 21:57:26 +0800

Patch-mainline: v5.5-rc1

Git-commit: 2d974619a77f106f3d1341686dea95c0eaad601f

References: bsc#1151910

Subject: [PATCH 1/2] btrfs: volumes: Use more straightforward way to calculate

 map length

The old code goes:

 	offset = logical - em->start;

	length = min_t(u64, em->len - offset, length);

Where @length calculation is dependent on offset, it can take reader

several more seconds to find it's just the same code as:

 	offset = logical - em->start;

	length = min_t(u64, em->start + em->len - logical, length);

Use above code to make the length calculate independent from other

variable, thus slightly increase the readability.

Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>

Reviewed-by: Josef Bacik <josef@toxicpanda.com>

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

Reviewed-by: David Sterba <dsterba@suse.com>

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

---

 fs/btrfs/volumes.c | 2 +-

 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c

index f534a6a5553e..6a0288d17b7d 100644

--- a/fs/btrfs/volumes.c

+++ b/fs/btrfs/volumes.c

@@ -5412,7 +5412,7 @@ static int __btrfs_map_block_for_discard(struct btrfs_fs_info *fs_info,

 	}

 	offset = logical - em->start;

-	length = min_t(u64, em->len - offset, length);

+	length = min_t(u64, em->start + em->len - logical, length);

 	stripe_len = map->stripe_len;

 	/*

-- 

2.24.1