On Sat, May 06, 2017 at 07:17:54AM +0800, Anand Jain wrote:
> This adds comments to the flush error handling part of
> the code, and hopes to maintain the same logic with a
> framework which can be used to handle the errors at the
> volume level.
>
> Signed-off-by: Anand Jain <anand.jain@xxxxxxxxxx>
Reviewed-by: David Sterba <dsterba@xxxxxxxx>
So the next step is to preallocate the flush_bio and remove the ENOMEM
handling.
I think we can skip the error handling on the submission path, even if
submit_bio can fail, the error code will be stored to the bio and this
will be checked in the waiting side.
Then write_dev_flush can be split into 2 functions by the parameter
'wait', as the paths are completely independent.
> +static int check_barrier_error(struct btrfs_fs_devices *fsdevs)
> +{
> + int submit_flush_error = 0;
> + int dev_flush_error = 0;
> + struct btrfs_device *dev;
> + int tolerance;
> +
> + list_for_each_entry_rcu(dev, &fsdevs->devices, dev_list) {
> + if (!dev->bdev) {
> + submit_flush_error++;
> + dev_flush_error++;
> + continue;
> + }
> + if (dev->last_flush_error == -ENOMEM)
> + submit_flush_error++;
> + if (dev->last_flush_error && dev->last_flush_error != -ENOMEM)
> + dev_flush_error++;
> + }
> +
> + tolerance = fsdevs->fs_info->num_tolerated_disk_barrier_failures;
> + if (submit_flush_error > tolerance || dev_flush_error > tolerance)
> + return -EIO;
Actually, after reading submit_bio and the comment above, do we need to
care about the submission errors? As submit_bio could return -EIO
immeditaelly, but does not help us anyway. We'll wait and check again
later. It's the bio completion what counts.
This should simplify the code.
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