Describe resize action in manual page.

man/integritysetup.8

@@ -54,6 +54,21 @@ Reports status for the active integrity mapping <name>.
 .IP
 Reports parameters from on-disk stored superblock.
 
+.PP
+\fIresize\fR <name>
+.IP
+Resizes an active mapping <name>.
+
+If \-\-size (in 512-bytes sectors) or \-\-device\-size are not specified,
+the size is computed from the underlying device. After resize, the
+\fBrecalculating\fR flag is set. If \-\-wipe flag is set and the size of the
+device is increased, the newly added section will be wiped.
+
+Increasing the size of integrity volumes is available since the Linux kernel
+version 5.7, shrinking should work on older kernels too.
+
+\fB<options>\fR can be [\-\-size, \-\-device\-size, \-\-wipe]
+
 .SH OPTIONS
 .TP
 .B "\-\-verbose, \-v"
@@ -93,6 +108,9 @@ due to need of full 64bit unsigned integers.
 .B "\-\-no\-wipe"
 Do not wipe the device after format. A device that is not initially wiped will contain invalid checksums.
 .TP
+.B "\-\-wipe"
+Wipe the newly allocated area after resize to bigger size. If this flag is not set, checksums will be calculated for the data previously stored in the newly allocated area.
+.TP
 .B "\-\-journal\-size, \-j BYTES"
 Size of the journal.
 .TP