mkfs: avoid divide-by-zero when hardware reports optimal i/o size as 0

Commit 051b4e37f5e (mkfs: factor AG alignment) factored out the
AG alignment code into a separate function.  It got rid of
redundant checks for dswidth != 0 since calc_stripe_factors was
supposed to guarantee that if dsunit is non-zero dswidth will be
as well.  Unfortunately, there's hardware out there that reports its
optimal i/o size as larger than the maximum i/o size, which the kernel
treats as broken and zeros out the optimal i/o size.

To resolve this we can check the topology before consuming it, and
ignore the bad stripe geometry.

Fixes: 051b4e37f5e (mkfs: factor AG alignment)
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
[sandeen: remove guessing heuristic, just warn and ignore bad data.]
Reviewed-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>

diff --git a/mkfs/xfs_mkfs.c b/mkfs/xfs_mkfs.c
index 1074886a098b77ce6dc75302a74c9cd7588d781a..2e53c1e83b6a77c73307a508638b3dae51387d7c 100644 (file)
--- a/mkfs/xfs_mkfs.c
+++ b/mkfs/xfs_mkfs.c
@@ -2281,11 +2281,20 @@ _("data stripe width (%d) must be a multiple of the data stripe unit (%d)\n"),
 
        /* if no stripe config set, use the device default */
        if (!dsunit) {
-               dsunit = ft->dsunit;
-               dswidth = ft->dswidth;
-               use_dev = true;
+               /* Ignore nonsense from device.  XXX add more validation */
+               if (ft->dsunit && ft->dswidth == 0) {
+                       fprintf(stderr,
+_("%s: Volume reports stripe unit of %d bytes and stripe width of 0, ignoring.\n"),
+                               progname, BBTOB(ft->dsunit));
+                       ft->dsunit = 0;
+                       ft->dswidth = 0;
+               } else {
+                       dsunit = ft->dsunit;
+                       dswidth = ft->dswidth;
+                       use_dev = true;
+               }
        } else {
-               /* check and warn is alignment is sub-optimal */
+               /* check and warn if user-specified alignment is sub-optimal */
                if (ft->dsunit && ft->dsunit != dsunit) {
                        fprintf(stderr,
 _("%s: Specified data stripe unit %d is not the same as the volume stripe unit %d\n"),