mkfs.xfs: properly handle physical sector size

This splits the fs_topology structure "sectorsize" into
logical & physical, and gets both via blkid_get_topology().

This primarily allows us to default to using the physical
sectorsize for mkfs's "sector size" value, the fundamental
size of any IOs the filesystem will perform.

We reduce mkfs.xfs's "sector size" to logical if
a block size < physical sector size is specified.
This is suboptimal, but permissable.

For block size < sector size, differentiate the error
message based on whether the sector size was manually
specified, or deduced.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

1 files changed, 44 insertions, 13 deletions

diff --git a/mkfs/xfs_mkfs.c b/mkfs/xfs_mkfs.c
index 140837a..d0c2eb6 100644
--- a/mkfs/xfs_mkfs.c
+++ b/mkfs/xfs_mkfs.c
@@ -33,7 +33,8 @@ struct fs_topology {
 	int	dsunit;		/* stripe unit - data subvolume */
 	int	dswidth;	/* stripe width - data subvolume */
 	int	rtswidth;	/* stripe width - rt subvolume */
-	int	sectorsize;
+	int	lsectorsize;	/* logical sector size &*/
+	int	psectorsize;	/* physical sector size */
 	int	sectoralign;
 };
 
@@ -373,7 +374,8 @@ static void blkid_get_topology(
 	const char	*device,
 	int		*sunit,
 	int		*swidth,
-	int		*sectorsize,
+	int		*lsectorsize,
+	int		*psectorsize,
 	int		force_overwrite)
 {
 
@@ -408,8 +410,11 @@ static void blkid_get_topology(
 	val = blkid_topology_get_optimal_io_size(tp) >> 9;
 	if (val > 1)
 		*swidth = val;
-	val = blkid_probe_get_sectorsize(pr);
-	*sectorsize = val;
+
+	val = blkid_topology_get_logical_sector_size(tp);
+	*lsectorsize = val;
+	val = blkid_topology_get_physical_sector_size(tp);
+	*psectorsize = val;
 
 	if (blkid_topology_get_alignment_offset(tp) != 0) {
 		fprintf(stderr,
@@ -422,8 +427,8 @@ static void blkid_get_topology(
 
 			exit(EXIT_FAILURE);
 		}
-		/* force a 512b sector size if the device is misaligned */
-		*sectorsize = BBSIZE;
+		/* Do not use physical sector size if the device is misaligned */
+		*psectorsize = *lsectorsize;
 	}
 
 	blkid_free_probe(pr);
@@ -445,14 +450,15 @@ static void get_topology(
 		const char *dfile = xi->volname ? xi->volname : xi->dname;
 
 		blkid_get_topology(dfile, &ft->dsunit, &ft->dswidth,
-				   &ft->sectorsize, force_overwrite);
+				   &ft->lsectorsize, &ft->psectorsize,
+				   force_overwrite);
 	}
 
 	if (xi->rtname && !xi->risfile) {
 		int dummy;
 
 		blkid_get_topology(xi->rtname, &dummy, &ft->rtswidth,
-				   &dummy, force_overwrite);
+				   &dummy, &dummy, force_overwrite);
 	}
 }
 #else /* ENABLE_BLKID */
@@ -1663,9 +1669,29 @@ main(
 	} else if (!ssflag) {
 		/*
 		 * Unless specified manually on the command line use the
-		 * advertised sector size of the device.
+		 * advertised sector size of the device.  We use the physical
+		 * sector size unless the requested block size is smaller
+		 * than that, then we can use logical, but warn about the
+		 * inefficiency.
 		 */
-		sectorsize = ft.sectorsize ? ft.sectorsize : XFS_MIN_SECTORSIZE;
+
+		/* Older kernels may not have physical/logical distinction */
+		if (!ft.psectorsize)
+			ft.psectorsize = ft.lsectorsize;
+
+		sectorsize = ft.psectorsize ? ft.psectorsize :
+					      XFS_MIN_SECTORSIZE;
+
+		if ((blocksize < sectorsize) && (blocksize >= ft.lsectorsize)) {
+			fprintf(stderr,
+_("specified blocksize %d is less than device physical sector size %d\n"),
+				blocksize, ft.psectorsize);
+			fprintf(stderr,
+_("switching to logical sector size %d\n"),
+				ft.lsectorsize);
+			sectorsize = ft.lsectorsize ? ft.lsectorsize :
+						      XFS_MIN_SECTORSIZE;
+		}
 	}
 
 	if (ft.sectoralign || !ssflag) {
@@ -1678,12 +1704,17 @@ main(
 
 	if (sectorsize < XFS_MIN_SECTORSIZE ||
 	    sectorsize > XFS_MAX_SECTORSIZE || sectorsize > blocksize) {
-		fprintf(stderr, _("illegal sector size %d\n"), sectorsize);
+		if (ssflag)
+			fprintf(stderr, _("illegal sector size %d\n"), sectorsize);
+		else
+			fprintf(stderr,
+_("block size %d cannot be smaller than logical sector size %d\n"),
+				blocksize, ft.lsectorsize);
 		usage();
 	}
-	if (sectorsize < ft.sectorsize) {
+	if (sectorsize < ft.lsectorsize) {
 		fprintf(stderr, _("illegal sector size %d; hw sector is %d\n"),
-			sectorsize, ft.sectorsize);
+			sectorsize, ft.lsectorsize);
 		usage();
 	}
 	if (lsectorsize < XFS_MIN_SECTORSIZE ||