Re: [PATCH 1/3] blkid: implement zone-aware probing

[Damien Le Moal <Damien.LeMoal@wdc.com>]

On 2021/04/14 7:11, Naohiro Aota wrote:
> This patch makes libblkid zone-aware. It can probe the magic located at
> some offset from the beginning of some specific zone of a device.
> 
> Ths patch introduces some new fields to struct blkid_idmag. They indicate
> the magic location is placed related to a zone, and the offset in the zone.
> 
> Also, this commit introduces `zone_size` to struct blkid_struct_probe. It
> stores the size of zones of a device.
> 
> Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
> ---
>  configure.ac          |  1 +
>  libblkid/src/blkidP.h |  5 +++++
>  libblkid/src/probe.c  | 26 ++++++++++++++++++++++++--
>  3 files changed, 30 insertions(+), 2 deletions(-)
> 
> diff --git a/configure.ac b/configure.ac
> index bebb4085425a..52b164e834db 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -302,6 +302,7 @@ AC_CHECK_HEADERS([ \
>  	lastlog.h \
>  	libutil.h \
>  	linux/btrfs.h \
> +	linux/blkzoned.h \
>  	linux/capability.h \
>  	linux/cdrom.h \
>  	linux/falloc.h \
> diff --git a/libblkid/src/blkidP.h b/libblkid/src/blkidP.h
> index a3fe6748a969..e3a160aa97c0 100644
> --- a/libblkid/src/blkidP.h
> +++ b/libblkid/src/blkidP.h
> @@ -150,6 +150,10 @@ struct blkid_idmag
>  	const char	*hoff;		/* hint which contains byte offset to kboff */
>  	long		kboff;		/* kilobyte offset of superblock */
>  	unsigned int	sboff;		/* byte offset within superblock */
> +
> +	int		is_zoned;	/* indicate magic location is calcluated based on zone position  */
> +	long		zonenum;	/* zone number which has superblock */
> +	long		kboff_inzone;	/* kilobyte offset of superblock in a zone */
>  };
>  
>  /*
> @@ -206,6 +210,7 @@ struct blkid_struct_probe
>  	dev_t			disk_devno;	/* devno of the whole-disk or 0 */
>  	unsigned int		blkssz;		/* sector size (BLKSSZGET ioctl) */
>  	mode_t			mode;		/* struct stat.sb_mode */
> +	uint64_t		zone_size;	/* zone size (BLKGETZONESZ ioctl) */
>  
>  	int			flags;		/* private library flags */
>  	int			prob_flags;	/* always zeroized by blkid_do_*() */
> diff --git a/libblkid/src/probe.c b/libblkid/src/probe.c
> index a47a8720d4ac..102766e57aa0 100644
> --- a/libblkid/src/probe.c
> +++ b/libblkid/src/probe.c
> @@ -94,6 +94,9 @@
>  #ifdef HAVE_LINUX_CDROM_H
>  #include <linux/cdrom.h>
>  #endif
> +#ifdef HAVE_LINUX_BLKZONED_H
> +#include <linux/blkzoned.h>
> +#endif
>  #ifdef HAVE_SYS_STAT_H
>  #include <sys/stat.h>
>  #endif
> @@ -871,6 +874,7 @@ int blkid_probe_set_device(blkid_probe pr, int fd,
>  #ifdef CDROM_GET_CAPABILITY
>  	long last_written = 0;
>  #endif
> +	uint32_t zone_size_sector;

Move this declaration under the # ifdef HAVE_LINUX_BLKZONED_H where it is used
below ?

>  
>  	blkid_reset_probe(pr);
>  	blkid_probe_reset_buffers(pr);
> @@ -897,6 +901,7 @@ int blkid_probe_set_device(blkid_probe pr, int fd,
>  	pr->wipe_off = 0;
>  	pr->wipe_size = 0;
>  	pr->wipe_chain = NULL;
> +	pr->zone_size = 0;
>  
>  	if (fd < 0)
>  		return 1;
> @@ -996,6 +1001,11 @@ int blkid_probe_set_device(blkid_probe pr, int fd,
>  #endif
>  	free(dm_uuid);
>  
> +# ifdef HAVE_LINUX_BLKZONED_H
> +	if (S_ISBLK(sb.st_mode) && !ioctl(pr->fd, BLKGETZONESZ, &zone_size_sector))
> +		pr->zone_size = zone_size_sector << 9;
> +# endif

So something like:

# ifdef HAVE_LINUX_BLKZONED_H
	if (S_ISBLK(sb.st_mode)) {
		 uint32_t zone_size_sector;

		if (!ioctl(pr->fd, BLKGETZONESZ, &zone_size_sector))
			pr->zone_size = zone_size_sector << 9;
	}
# endif

Otherwise, you probably will get a compiler warning as zone_size_sector will be
unused if HAVE_LINUX_BLKZONED_H is false.

> +
>  	DBG(LOWPROBE, ul_debug("ready for low-probing, offset=%"PRIu64", size=%"PRIu64"",
>  				pr->off, pr->size));
>  	DBG(LOWPROBE, ul_debug("whole-disk: %s, regfile: %s",
> @@ -1064,12 +1074,24 @@ int blkid_probe_get_idmag(blkid_probe pr, const struct blkid_idinfo *id,
>  	/* try to detect by magic string */
>  	while(mag && mag->magic) {
>  		unsigned char *buf;
> +		uint64_t kboff;
>  		uint64_t hint_offset;
>  
>  		if (!mag->hoff || blkid_probe_get_hint(pr, mag->hoff, &hint_offset) < 0)
>  			hint_offset = 0;
>  
> -		off = hint_offset + ((mag->kboff + (mag->sboff >> 10)) << 10);
> +		/* If the magic is for zoned device, skip non-zoned device */
> +		if (mag->is_zoned && !pr->zone_size) {
> +			mag++;
> +			continue;
> +		}
> +
> +		if (!mag->is_zoned)
> +			kboff = mag->kboff;
> +		else
> +			kboff = ((mag->zonenum * pr->zone_size) >> 10) + mag->kboff_inzone;
> +
> +		off = hint_offset + ((kboff + (mag->sboff >> 10)) << 10);
>  		buf = blkid_probe_get_buffer(pr, off, 1024);
>  
>  		if (!buf && errno)
> @@ -1079,7 +1101,7 @@ int blkid_probe_get_idmag(blkid_probe pr, const struct blkid_idinfo *id,
>  				buf + (mag->sboff & 0x3ff), mag->len)) {
>  
>  			DBG(LOWPROBE, ul_debug("\tmagic sboff=%u, kboff=%ld",
> -				mag->sboff, mag->kboff));
> +				mag->sboff, kboff));
>  			if (offset)
>  				*offset = off + (mag->sboff & 0x3ff);
>  			if (res)
> 


-- 
Damien Le Moal
Western Digital Research