Re: [PATCH] generic/223: port t_stripealign to FIEMAP

[Eryu Guan <guaneryu@gmail.com>]

On Wed, Jun 13, 2018 at 03:50:57PM -0700, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@oracle.com>
> 
> Since XFS has deprecated FIBMAP on FSDAX filesystems, we can't use
> FIBMAP to verify stripe alignment anymore.  FIEMAP has existed for quite
> some time now, so port it to use that instead, and only fall back to
> FIBMAP if FIEMAP doesn't exist.
> 
> Tested-by: ross.zwisler@linux.intel.com
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> ---
>  src/t_stripealign.c |   72 +++++++++++++++++++++++++++++++++++++++++++--------
>  1 file changed, 61 insertions(+), 11 deletions(-)
> 
> diff --git a/src/t_stripealign.c b/src/t_stripealign.c
> index 05ed36b5..690f743a 100644
> --- a/src/t_stripealign.c
> +++ b/src/t_stripealign.c
> @@ -17,8 +17,13 @@
>  #include <fcntl.h>
>  #include <stdio.h>
>  #include <sys/ioctl.h>
> +#include <linux/fiemap.h>
> +#include <linux/fs.h>

As it requires <linux/fiemap.h> now, looks like we should update
src/Makefile too to only compile it when "HAVE_FIEMAP" is true.

ifeq ($(HAVE_FIEMAP), true)
LINUX_TARGETS += fiemap-tester t_stripealign
endif

Thanks,
Eryu

P.S.

LINUX_TARGETS could be cleaned up and merged with TARGETS, it's useless
to have both TARGETS and LINUX_TARGETS defined now, as we only support
Linux platform, but that's a different issue.

>  
> -#define FIBMAP          _IO(0x00, 1)    /* bmap access */
> +#define FIEMAP_EXTENT_ACCEPTABLE	(FIEMAP_EXTENT_LAST | \
> +		FIEMAP_EXTENT_DATA_ENCRYPTED | FIEMAP_EXTENT_ENCODED | \
> +		FIEMAP_EXTENT_UNWRITTEN | FIEMAP_EXTENT_MERGED | \
> +		FIEMAP_EXTENT_SHARED)
>  
>  /*
>   * If only filename given, print first block.
> @@ -28,11 +33,14 @@
>  
>  int main(int argc, char ** argv)
>  {
> -	int	fd;
> -	int	ret;
> -	int	sunit = 0;	/* in blocks */
> -	char	*filename;
> -	unsigned int	block = 0;
> +	struct stat		sb;
> +	struct fiemap		*fie;
> +	struct fiemap_extent	*fe;
> +	int			fd;
> +	int			ret;
> +	int			sunit = 0;	/* in blocks */
> +	char			*filename;
> +	unsigned long long	block;
>  
>          if (argc < 3) {
>                  printf("Usage: %s <filename> <sunit in blocks>\n", argv[0]);
> @@ -48,21 +56,63 @@ int main(int argc, char ** argv)
>                  return 1;
>          }
>  
> -	ret = ioctl(fd, FIBMAP, &block);
> -	if (ret < 0) {
> +	ret = fstat(fd, &sb);
> +	if (ret) {
> +		perror(filename);
>  		close(fd);
> -		perror("fibmap");
>  		return 1;
>  	}
>  
> -	close(fd);
> +	fie = calloc(1, sizeof(struct fiemap) + sizeof(struct fiemap_extent));
> +	if (!fie) {
> +		close(fd);
> +		perror("malloc");
> +		return 1;
> +	}
> +	fie->fm_length = 1;
> +	fie->fm_flags = FIEMAP_FLAG_SYNC;
> +	fie->fm_extent_count = 1;
> +
> +	ret = ioctl(fd, FS_IOC_FIEMAP, fie);
> +	if (ret < 0) {
> +		unsigned int	bmap = 0;
> +
> +		ret = ioctl(fd, FIBMAP, &bmap);
> +		if (ret < 0) {
> +			perror("fibmap");
> +			free(fie);
> +			close(fd);
> +			return 1;
> +		}
> +		block = bmap;
> +		goto check;
> +	}
>  
> +
> +	if (fie->fm_mapped_extents != 1) {
> +		printf("%s: no extents?\n", filename);
> +		free(fie);
> +		close(fd);
> +		return 1;
> +	}
> +	fe = &fie->fm_extents[0];
> +	if (fe->fe_flags & ~FIEMAP_EXTENT_ACCEPTABLE) {
> +		printf("%s: bad flags 0x%x\n", filename, fe->fe_flags);
> +		free(fie);
> +		close(fd);
> +		return 1;
> +	}
> +
> +	block = fie->fm_extents[0].fe_physical / sb.st_blksize;
> +check:
>  	if (block % sunit) {
> -		printf("%s: Start block %u not multiple of sunit %u\n",
> +		printf("%s: Start block %llu not multiple of sunit %u\n",
>  			filename, block, sunit);
>  		return 1;
>  	} else
>  		printf("%s: well-aligned\n", filename);
> +	free(fie);
> +	close(fd);
>  
>  	return 0;
>  }