xfs: use %px for data pointers when debugging

Starting with commit 57e734423a ("vsprintf: refactor %pK code out of
pointer"), the behavior of the raw '%p' printk format specifier was
changed to print a 32-bit hash of the pointer value to avoid leaking
kernel pointers into dmesg.  For most situations that's good.

This is /undesirable/ behavior when we're trying to debug XFS, however,
so define a PTR_FMT that prints the actual pointer when we're in debug
mode.

Note that %p for tracepoints still prints the raw pointer, so in the
long run we could consider rewriting some of these messages as
tracepoints.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

fs/xfs/xfs_qm.c

@@ -162,7 +162,7 @@ xfs_qm_dqpurge(
 		 */
 		error = xfs_qm_dqflush(dqp, &bp);
 		if (error) {
-			xfs_warn(mp, "%s: dquot %p flush failed",
+			xfs_warn(mp, "%s: dquot "PTR_FMT" flush failed",
 				__func__, dqp);
 		} else {
 			error = xfs_bwrite(bp);
@@ -480,7 +480,7 @@ xfs_qm_dquot_isolate(
 
 		error = xfs_qm_dqflush(dqp, &bp);
 		if (error) {
-			xfs_warn(dqp->q_mount, "%s: dquot %p flush failed",
+			xfs_warn(dqp->q_mount, "%s: dquot "PTR_FMT" flush failed",
 				 __func__, dqp);
 			goto out_unlock_dirty;
 		}