Re: [RFC v3 3/5] file-posix: introduce get_sysfs_long_val for zoned device information.

[Hannes Reinecke <hare@suse.de>]

On 6/27/22 02:19, Sam Li wrote:
> Use sysfs attribute files to get the zoned device information in case
> that ioctl() commands of zone management interface won't work. It can
> return long type of value like chunk_sectors, zoned_append_max_bytes,
> max_open_zones, max_active_zones.
> ---
>   block/file-posix.c | 37 +++++++++++++++++++++++++------------
>   1 file changed, 25 insertions(+), 12 deletions(-)
> 
> diff --git a/block/file-posix.c b/block/file-posix.c
> index 1b8b0d351f..73c2cdfbca 100644
> --- a/block/file-posix.c
> +++ b/block/file-posix.c
> @@ -1216,15 +1216,19 @@ static int hdev_get_max_hw_transfer(int fd, struct stat *st)
>   #endif
>   }
>   
> -static int hdev_get_max_segments(int fd, struct stat *st)
> -{
> +/*
> + * Get zoned device information (chunk_sectors, zoned_append_max_bytes,
> + * max_open_zones, max_active_zones) through sysfs attribute files.
> + */
> +static long get_sysfs_long_val(int fd, struct stat *st,
> +                               const char *attribute) {
>   #ifdef CONFIG_LINUX
>       char buf[32];
>       const char *end;
>       char *sysfspath = NULL;
>       int ret;
>       int sysfd = -1;
> -    long max_segments;
> +    long val;
>   
>       if (S_ISCHR(st->st_mode)) {
>           if (ioctl(fd, SG_GET_SG_TABLESIZE, &ret) == 0) {
> @@ -1237,8 +1241,9 @@ static int hdev_get_max_segments(int fd, struct stat *st)
>           return -ENOTSUP;
>       }
>   
> -    sysfspath = g_strdup_printf("/sys/dev/block/%u:%u/queue/max_segments",
> -                                major(st->st_rdev), minor(st->st_rdev));
> +    sysfspath = g_strdup_printf("/sys/dev/block/%u:%u/queue/%s",
> +                                major(st->st_rdev), minor(st->st_rdev),
> +                                attribute);
>       sysfd = open(sysfspath, O_RDONLY);
>       if (sysfd == -1) {
>           ret = -errno;
> @@ -1256,9 +1261,9 @@ static int hdev_get_max_segments(int fd, struct stat *st)
>       }
>       buf[ret] = 0;
>       /* The file is ended with '\n', pass 'end' to accept that. */
> -    ret = qemu_strtol(buf, &end, 10, &max_segments);
> +    ret = qemu_strtol(buf, &end, 10, &val);
>       if (ret == 0 && end && *end == '\n') {
> -        ret = max_segments;
> +        ret = val;
>       }
>   
>   out:
> @@ -1272,6 +1277,15 @@ out:
>   #endif
>   }
>   
> +static int hdev_get_max_segments(int fd, struct stat *st) {
> +    int ret;
> +    ret = get_sysfs_long_val(fd, st, "max_segments");
> +    if (ret < 0) {
> +        return -1;
> +    }
> +    return ret;
> +}
> +
>   static void raw_refresh_limits(BlockDriverState *bs, Error **errp)
>   {
>       BDRVRawState *s = bs->opaque;
> @@ -1872,6 +1886,7 @@ static int handle_aiocb_zone_report(void *opaque) {
>   
>   static int handle_aiocb_zone_mgmt(void *opaque) {
>       RawPosixAIOData *aiocb = opaque;
> +    BlockDriverState *s = aiocb->bs;
>       int fd = aiocb->aio_fildes;
>       int64_t offset = aiocb->aio_offset;
>       int64_t len = aiocb->aio_nbytes;
> @@ -1884,11 +1899,9 @@ static int handle_aiocb_zone_mgmt(void *opaque) {
>       int64_t zone_size_mask;
>       int ret;
>   
> -    ret = ioctl(fd, BLKGETZONESZ, &zone_size);
> -    if (ret) {
> -        return -1;
> -    }
> -
> +    g_autofree struct stat *file = g_new(struct stat, 1);
> +    stat(s->filename, file);
> +    zone_size = get_sysfs_long_val(fd, file, "chunk_sectors");
>       zone_size_mask = zone_size - 1;
>       if (offset & zone_size_mask) {
>           error_report("offset is not the start of a zone");

Round of applause.

Reviewed-by: Hannes Reinecke <hare@suse.de>

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		           Kernel Storage Architect
hare@suse.de			                  +49 911 74053 688
SUSE Software Solutions Germany GmbH, Maxfeldstr. 5, 90409 Nürnberg
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