On 15.01.2018 08:13, Qu Wenruo wrote:
> Enospc_debug makes extent allocator to print more debug messages,
> however for chunk allocation, there is no debug message for enospc_debug
> at all.
>
> This patch will add message for the following parts of chunk allocator:
>
> 1) No rw device at all
> Quite rare, but at least output one message for this case.
>
> 2) No enough space for some device
> This debug message is quite handy for unbalanced disks with stripe
> based profiles (RAID0/10/5/6).
>
> 3) Not enough free devices
> This debug message should tell us if current chunk allocator is
> working correctly on minimal device requirement.
>
> Although under most case, we will hit other ENOSPC before we even hit a
> chunk allocator ENOSPC, but such debug info won't help.
>
> Signed-off-by: Qu Wenruo <wqu@xxxxxxxx>
> ---
> fs/btrfs/volumes.c | 19 +++++++++++++++++--
> 1 file changed, 17 insertions(+), 2 deletions(-)
>
> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
> index a25684287501..664d8a1b90b3 100644
> --- a/fs/btrfs/volumes.c
> +++ b/fs/btrfs/volumes.c
> @@ -4622,8 +4622,11 @@ static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
>
> BUG_ON(!alloc_profile_is_valid(type, 0));
>
> - if (list_empty(&fs_devices->alloc_list))
> + if (list_empty(&fs_devices->alloc_list)) {
> + if (btrfs_test_opt(info, ENOSPC_DEBUG))
> + btrfs_warn(info, "%s: No writable device", __func__);
perhaps this shouldn't be gated on ENOSPC_DEBUG if it's a warning, or if
it's to be gated then make it a DEBUG.
> return -ENOSPC;
> + }
>
> index = __get_raid_index(type);
>
> @@ -4705,8 +4708,14 @@ static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
> if (ret == 0)
> max_avail = max_stripe_size * dev_stripes;
>
> - if (max_avail < BTRFS_STRIPE_LEN * dev_stripes)
> + if (max_avail < BTRFS_STRIPE_LEN * dev_stripes) {
> + if (btrfs_test_opt(info, ENOSPC_DEBUG))
> + btrfs_debug(info,
> + "%s: devid %llu has no free space, have=%llu want=%u",
> + __func__, device->devid, max_avail,
> + BTRFS_STRIPE_LEN * dev_stripes);
Here we have a debug output gated on ENOSCP_DEBUG so let's be consistent
(hence my previous comment)
> continue;
> + }
>
> if (ndevs == fs_devices->rw_devices) {
> WARN(1, "%s: found more than %llu devices\n",
> @@ -4731,6 +4740,12 @@ static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
>
> if (ndevs < devs_increment * sub_stripes || ndevs < devs_min) {
> ret = -ENOSPC;
> + if (btrfs_test_opt(info, ENOSPC_DEBUG)) {
> + btrfs_debug(info,
> + "%s: not enough devices with free space: have=%d minimal=%d increment=%d",
> + __func__, ndevs, devs_min,
> + devs_increment * sub_stripes);
Without looking at the code it's not really obvious what increment is.
Perhaps you can use a more descriptive word?
> + }
> goto error;
> }
>
>
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