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SubjectRe: [PATCH] add label interface for cache device in sysfs
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On 9/14/18 5:51 PM, Dongbo Cao wrote:
> label interface will be called by bcache tools in user space.
>
> Signed-off-by: Dongbo Cao <cdbdyx@163.com>

Hi Dongbo,


In your change I see you set superblock label to cache set. What is the
use case for doing this ?

Thanks.


Coly Li


> ---
> drivers/md/bcache/sysfs.c | 19 +++++++++++++++++++
> 1 file changed, 19 insertions(+)
>
> diff --git a/drivers/md/bcache/sysfs.c b/drivers/md/bcache/sysfs.c
> index 225b15aa..e64c718f 100644
> --- a/drivers/md/bcache/sysfs.c
> +++ b/drivers/md/bcache/sysfs.c
> @@ -950,6 +950,13 @@ SHOW(__bch_cache)
> return ret;
> }
>
> + if (attr == &sysfs_label) {
> + memcpy(buf, ca->sb.label, SB_LABEL_SIZE);
> + buf[SB_LABEL_SIZE + 1] = '\0';
> + strcat(buf, "\n");
> + return strlen(buf);
> + }
> +
> return 0;
> }
> SHOW_LOCKED(bch_cache)
> @@ -993,6 +1000,17 @@ STORE(__bch_cache)
> atomic_set(&ca->io_errors, 0);
> }
>
> + if (attr == &sysfs_label) {
> + if (size > SB_LABEL_SIZE)
> + return -EINVAL;
> + memcpy(ca->sb.label, buf, size);
> + if (size < SB_LABEL_SIZE)
> + ca->sb.label[size] = '\0';
> + if (size && ca->sb.label[size - 1] == '\n')
> + ca->sb.label[size - 1] = '\0';
> + bcache_write_super(ca->set);
> + }
> +
> return size;
> }
> STORE_LOCKED(bch_cache)
> @@ -1009,6 +1027,7 @@ static struct attribute *bch_cache_files[] = {
> &sysfs_io_errors,
> &sysfs_clear_stats,
> &sysfs_cache_replacement_policy,
> + &sysfs_label,
> NULL
> };
> KTYPE(bch_cache);

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