Re: [PATCH 4/4] libfrog: enable cached report zones

["Darrick J. Wong" <djwong@kernel.org>]

On Fri, Jan 09, 2026 at 05:22:55PM +0100, Christoph Hellwig wrote:
> From: Damien Le Moal <dlemoal@kernel.org>
> 
> Modify the function xfrog_report_zones() to default to always trying
> first a cached report zones using the BLKREPORTZONEV2 ioctl.
> If the kernel does not support BLKREPORTZONEV2, fall back to the
> (slower) regular report zones BLKREPORTZONE ioctl.
> 
> TO enable this feature even if xfsprogs is compiled on a system where
> linux/blkzoned.h does not define BLKREPORTZONEV2, this ioctl is defined
> in libfrog/zones.h, together with the BLK_ZONE_REP_CACHED flag and the
> BLK_ZONE_COND_ACTIVE zone condition.
> 
> Since a cached report zone  always return the condition
> BLK_ZONE_COND_ACTIVE for any zone that is implicitly open, explicitly
> open or closed, the function xfs_zone_validate_seq() is modified to
> handle this new condition as being equivalent to the implicit open,
> explicit open or closed conditions.
> 
> Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
> [hch: don't try cached reporting again if not supported]
> Signed-off-by: Christoph Hellwig <hch@lst.de>

That's an amusing use of atomic_t :)
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>

--D

> ---
>  libfrog/zones.c | 31 ++++++++++++++++++++++++++++++-
>  1 file changed, 30 insertions(+), 1 deletion(-)
> 
> diff --git a/libfrog/zones.c b/libfrog/zones.c
> index 2276c56bec9c..f1ef0b24c564 100644
> --- a/libfrog/zones.c
> +++ b/libfrog/zones.c
> @@ -3,12 +3,24 @@
>   * Copyright (c) 2025, Western Digital Corporation or its affiliates.
>   */
>  #include "platform_defs.h"
> +#include "atomic.h"
>  #include "libfrog/zones.h"
>  #include <sys/ioctl.h>
>  
> +/*
> + * Cached report ioctl (/usr/include/linux/blkzoned.h).
> + * Add in Linux 6.19.
> + */
> +#ifndef BLKREPORTZONEV2
> +#define BLKREPORTZONEV2		_IOWR(0x12, 142, struct blk_zone_report)
> +#define BLK_ZONE_REP_CACHED	(1U << 31)
> +#endif /* BLKREPORTZONEV2 */
> +
>  /* random size that allows efficient processing */
>  #define ZONES_PER_REPORT		16384
>  
> +static atomic_t cached_reporting_disabled;
> +
>  struct xfrog_zone_report *
>  xfrog_report_zones(
>  	int			fd,
> @@ -24,10 +36,27 @@ _("Failed to allocate memory for reporting zones."));
>  		}
>  	}
>  
> +	/*
> +	 * Try cached report zones first. If this fails, fallback to the regular
> +	 * (slower) report zones.
> +	 */
>  	rep->rep.sector = sector;
>  	rep->rep.nr_zones = ZONES_PER_REPORT;
>  
> -	if (ioctl(fd, BLKREPORTZONE, &rep->rep)) {
> +	if (atomic_read(&cached_reporting_disabled))
> +		goto uncached;
> +
> +	rep->rep.flags = BLK_ZONE_REP_CACHED;
> +	if (ioctl(fd, BLKREPORTZONEV2, &rep->rep)) {
> +		atomic_inc(&cached_reporting_disabled);
> +		goto uncached;
> +	}
> +
> +	return rep;
> +
> +uncached:
> +	rep->rep.flags = 0;
> +	if (ioctl(fd, BLKREPORTZONE, rep)) {
>  		fprintf(stderr, "%s %s\n",
>  _("ioctl(BLKREPORTZONE) failed:\n"),
>  			strerror(-errno));
> -- 
> 2.47.3
> 
>