btrfs: volumes: Remove the meaningless condition of minimal nr_devs when allocating...

When checking the minimal nr_devs, there is one dead and meaningless
condition:

if (ndevs < devs_increment * sub_stripes || ndevs < devs_min) {
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

This condition is meaningless, @devs_increment has nothing to do with
@sub_stripes.

In fact, in btrfs_raid_array[], profile with sub_stripes larger than 1
(RAID10) already has the @devs_increment set to 2.
So no need to multiple it by @sub_stripes.

And above condition is also dead.
For RAID10, @devs_increment * @sub_stripes equals 4, which is also the
@devs_min of RAID10.
For other profiles, @sub_stripes is always 1, and since @ndevs is
rounded down to @devs_increment, the condition will always be true.

Remove the meaningless condition to make later reader wander less.

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

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 1e72357bdfa8b44d41e523eddc8111e8ca9421a5..dcc2b486b2c5e2ec43d025f5ae3dd82d3006a1ca 100644 (file)
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -4837,13 +4837,12 @@ static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
        /* round down to number of usable stripes */
        ndevs = round_down(ndevs, devs_increment);
 
-       if (ndevs < devs_increment * sub_stripes || ndevs < devs_min) {
+       if (ndevs < devs_min) {
                ret = -ENOSPC;
                if (btrfs_test_opt(info, ENOSPC_DEBUG)) {
                        btrfs_debug(info,
        "%s: not enough devices with free space: have=%d minimum required=%d",
-                                   __func__, ndevs, min(devs_min,
-                                   devs_increment * sub_stripes));
+                                   __func__, ndevs, devs_min);
                }
                goto error;
        }