mount: add info about semantics of read-only mount to mount.8

Reported-by: Joachim Wagner <jwagner@computing.dcu.ie>
Signed-off-by: Karel Zak <kzak@redhat.com>

diff --git a/mount/mount.8 b/mount/mount.8
index 50655f0bed089f21490419143bf706e7fa656c6a..bbbbd33a8d56e20bbe2570fe34a7e3a08d489668 100644 (file)
--- a/mount/mount.8
+++ b/mount/mount.8
@@ -424,6 +424,12 @@ autofs\-based automounter.
 .B \-r
 Mount the file system read-only. A synonym is
 .BR "\-o ro" .
+
+Note that, depending on the filesystem type, state and kernel behavior, the
+system may still write to the device. For example, Ext3 will replay its journal
+if the filesystem is dirty. To prevent this kind of write access, you may want
+to map the device through a read-only loop device, see command
+.BR losetup (8).
 .TP
 .B \-w
 Mount the file system read/write. This is the default. A synonym is