Re: [PATCH] mkfs.xfs: always use underlying fs sector size when mkfs'ing a file

[Jan Tulak <jtulak@redhat.com>]

----- Original Message -----
> From: "Eric Sandeen" <sandeen@sandeen.net>
> To: "Jan Tulak" <jtulak@redhat.com>, "Eric Sandeen" <sandeen@redhat.com>
> Cc: "xfs-oss" <xfs@oss.sgi.com>
> Sent: Thursday, June 18, 2015 4:57:09 PM
> Subject: Re: [PATCH] mkfs.xfs: always use underlying fs sector size when	mkfs'ing a file
> 
> On 6/18/15 6:03 AM, Jan Tulak wrote:
> > 
> > 
> > ----- Original Message -----
> >> From: "Eric Sandeen" <sandeen@redhat.com>
> >> To: "xfs-oss" <xfs@oss.sgi.com>
> >> Sent: Thursday, June 18, 2015 1:26:33 AM
> >> Subject: [PATCH] mkfs.xfs: always use underlying fs sector size when
> >> mkfs'ing	a file
> >>
> >> If we are mkfs'ing a file, and that file is on a 4k sector filesystem,
> >> we should make the fs image file with the same sector size, or things
> >> may fail when they try to do direct IO in 512 byte chunks (depending
> >> on whether it is a 512e or "hard" 4k device).
> >>
> >> Earlier commits attempted this to some degree:
> >>
> >> 5a7d59 xfsprogs: try to handle mkfs of a file on 4k sector device
> >> 3800a2 mkfs.xfs: don't call blkid_get_topology on existing regular files
> >>
> >> but inexplicably missed the case where mkfs.xfs with "-d file" was
> >> specified.
> >>
> >> One more try; in get_topology(), try to get the underlying fs sector
> >> size in *all* cases where we are mkfs'ing a file, and set the sector size
> >> accordingly.
> >>
> >> Signed-off-by: Eric Sandeen <sandeen@redhat.com>
> >> ---
> >>
> >> (This does it for 512e as well as hard 4k drives, but I think that's
> >> probably ok?  If not, perhaps we should go further and attempt to
> >> discern logical and physical sectors for the device under the
> >> filesystem.  Is it worth it?  Not sure it is.)
> >>
> >> diff --git a/mkfs/xfs_mkfs.c b/mkfs/xfs_mkfs.c
> >> index e2a052d..e44c390 100644
> >> --- a/mkfs/xfs_mkfs.c
> >> +++ b/mkfs/xfs_mkfs.c
> >> @@ -462,31 +462,34 @@ static void get_topology(
> >>  	struct fs_topology	*ft,
> >>  	int			force_overwrite)
> >>  {
> >> -	if (!xi->disfile) {
> >> -		char *dfile = xi->volname ? xi->volname : xi->dname;
> >> -		struct stat statbuf;
> >> +	struct stat statbuf;
> >> +	char *dfile = xi->volname ? xi->volname : xi->dname;
> >>  
> >> -		/*
> >> -		 * If our target is a regular file, and xi->disfile isn't
> >> -		 * set (i.e. no "-d file" invocation), use platform_findsizes
> >> -		 * to try to obtain the underlying filesystem's requirements
> >> -		 * for direct IO; we'll set our sector size to that if possible.
> >> -		 */
> >> -		if (!stat(dfile, &statbuf) && S_ISREG(statbuf.st_mode)) {
> >> -			int fd;
> >> -			long long dummy;
> >> -
> >> -			fd = open(dfile, O_RDONLY);
> >> -			if (fd >= 0) {
> >> -				platform_findsizes(dfile, fd, &dummy,
> >> -						   &ft->lsectorsize);
> >> -				close(fd);
> >> -			}
> >> -		} else {
> >> -			blkid_get_topology(dfile, &ft->dsunit, &ft->dswidth,
> >> -					   &ft->lsectorsize, &ft->psectorsize,
> >> -					   force_overwrite);
> >> +	/*
> >> +	 * If our target is a regular file, use platform_findsizes
> >> +	 * to try to obtain the underlying filesystem's requirements
> >> +	 * for direct IO; we'll set our sector size to that if possible.
> >> +	 */
> >> +	if (xi->disfile ||
> >> +	    (!stat(dfile, &statbuf) && S_ISREG(statbuf.st_mode))) {
> >> +		int fd;
> >> +		int flags = O_RDONLY;
> >> +		long long dummy;
> >> +
> >> +		/* with xi->disfile we may not have the file yet! */
> >> +		if (xi->disfile)
> >> +			flags |= O_CREAT;
> >> +
> >> +		fd = open(dfile, flags, 0666);
> >> +		if (fd >= 0) {
> >> +			platform_findsizes(dfile, fd, &dummy, &ft->lsectorsize);
> >> +			close (fd);
> >>  		}
> >> +
> >> +	} else {
> >> +		blkid_get_topology(dfile, &ft->dsunit, &ft->dswidth,
> >> +				   &ft->lsectorsize, &ft->psectorsize,
> >> +				   force_overwrite);
> >>  	}
> >>  
> >>  	if (xi->rtname && !xi->risfile) {
> >>
> > 
> > This changes get_topology only for ENABLE_BLKID branch of #ifdef. Is
> > that intentional, i.e. we don't expect anyone not using ENABLE_BLKID?
> > Because otherwise, if mkfs is compiled without ENABLE_BLKID, then all
> > we get is:
> 
> Hm, yeah, good point.  I always forget about this.  :(  I can send V2.
> 
> And sorry if this overlaps w/ your changes- 

No problem. :-)

Cheers,
Jan

-- 
Jan Tulak
jtulak@redhat.com

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