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

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>
This commit is contained in:
Qu Wenruo 2018-01-31 13:56:15 +08:00 committed by David Sterba
parent 6f47c706d9
commit ba89b80268
1 changed files with 2 additions and 3 deletions
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5
fs/btrfs/volumes.c
View File

@ -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;
}