Re: [PATCH v2] mkfs.xfs: fix ASSERT on too-small device with stripe geometry

[Carlos Maiolino <cmaiolino@redhat.com>]

On Wed, Sep 16, 2020 at 10:40:56PM +0200, Pavel Reichl wrote:
> When a too-small device is created with stripe geometry, we hit an
> assert in align_ag_geometry():
> 
> mkfs.xfs: xfs_mkfs.c:2834: align_ag_geometry: Assertion `cfg->agcount != 0' failed.
> 
> This is because align_ag_geometry() finds that the size of the last
> (only) AG is too small, and attempts to trim it off.  Obviously 0
> AGs is invalid, and we hit the ASSERT.
> 

Patch looks good, next time please keep the Changelog :)
Cheers.

Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>

> Reported-by: Zdenek Kabelac <zkabelac@redhat.com>
> Suggested-by: Dave Chinner <dchinner@redhat.com>
> Signed-off-by: Pavel Reichl <preichl@redhat.com>
> ---
>  include/xfs_multidisk.h | 14 +++++++-------
>  mkfs/xfs_mkfs.c         |  6 +++---
>  2 files changed, 10 insertions(+), 10 deletions(-)
> 
> diff --git a/include/xfs_multidisk.h b/include/xfs_multidisk.h
> index 1b9936ec..abfb50ce 100644
> --- a/include/xfs_multidisk.h
> +++ b/include/xfs_multidisk.h
> @@ -14,7 +14,6 @@
>  #define	XFS_DFL_BLOCKSIZE_LOG	12		/* 4096 byte blocks */
>  #define	XFS_DINODE_DFL_LOG	8		/* 256 byte inodes */
>  #define	XFS_DINODE_DFL_CRC_LOG	9		/* 512 byte inodes for CRCs */
> -#define	XFS_MIN_DATA_BLOCKS	100
>  #define	XFS_MIN_INODE_PERBLOCK	2		/* min inodes per block */
>  #define	XFS_DFL_IMAXIMUM_PCT	25		/* max % of space for inodes */
>  #define	XFS_MIN_REC_DIRSIZE	12		/* 4096 byte dirblocks (V2) */
> @@ -25,13 +24,14 @@
>  						 * accept w/o warnings
>  						 */
>  
> -#define XFS_AG_BYTES(bblog)	((long long)BBSIZE << (bblog))
> -#define	XFS_AG_MIN_BYTES	((XFS_AG_BYTES(15)))	/* 16 MB */
> -#define	XFS_AG_MAX_BYTES	((XFS_AG_BYTES(31)))	/* 1 TB */
> -#define XFS_AG_MIN_BLOCKS(blog)	(XFS_AG_MIN_BYTES >> (blog))
> -#define XFS_AG_MAX_BLOCKS(blog)	((XFS_AG_MAX_BYTES - 1) >> (blog))
> +#define XFS_AG_BYTES(bblog)		((long long)BBSIZE << (bblog))
> +#define	XFS_MIN_DATA_BLOCKS(cfg)	(XFS_AG_MIN_BLOCKS((cfg)->blocklog))
> +#define	XFS_AG_MIN_BYTES		((XFS_AG_BYTES(15)))	/* 16 MB */
> +#define	XFS_AG_MAX_BYTES		((XFS_AG_BYTES(31)))	/* 1 TB */
> +#define XFS_AG_MIN_BLOCKS(blog)		(XFS_AG_MIN_BYTES >> (blog))
> +#define XFS_AG_MAX_BLOCKS(blog)		((XFS_AG_MAX_BYTES - 1) >> (blog))
>  
> -#define XFS_MAX_AGNUMBER	((xfs_agnumber_t)(NULLAGNUMBER - 1))
> +#define XFS_MAX_AGNUMBER		((xfs_agnumber_t)(NULLAGNUMBER - 1))
>  
>  /*
>   * These values define what we consider a "multi-disk" filesystem. That is, a
> diff --git a/mkfs/xfs_mkfs.c b/mkfs/xfs_mkfs.c
> index a687f385..204dfff1 100644
> --- a/mkfs/xfs_mkfs.c
> +++ b/mkfs/xfs_mkfs.c
> @@ -2530,10 +2530,10 @@ _("size %s specified for data subvolume is too large, maximum is %lld blocks\n")
>  		cfg->dblocks = DTOBT(xi->dsize, cfg->blocklog);
>  	}
>  
> -	if (cfg->dblocks < XFS_MIN_DATA_BLOCKS) {
> +	if (cfg->dblocks < XFS_MIN_DATA_BLOCKS(cfg)) {
>  		fprintf(stderr,
> -_("size %lld of data subvolume is too small, minimum %d blocks\n"),
> -			(long long)cfg->dblocks, XFS_MIN_DATA_BLOCKS);
> +_("size %lld of data subvolume is too small, minimum %lld blocks\n"),
> +			(long long)cfg->dblocks, XFS_MIN_DATA_BLOCKS(cfg));
>  		usage();
>  	}
>  
> -- 
> 2.26.2
> 

-- 
Carlos