trivial: document ext3 semantics of 'ro' option a bit better

ext3 has quite unexpected semantics or "ro" and defaults are
not what they are documented to be, due to mkfs override.

Signed-off-by: Pavel Machek <pavel@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

diff --git a/Documentation/filesystems/ext3.txt b/Documentation/filesystems/ext3.txt
index e5f3833a6ef8f53c3b22adf48d57b84e2a24ba0c..570f9bd9be2becb3fee1c7869d9c911226690dc4 100644 (file)
--- a/Documentation/filesystems/ext3.txt
+++ b/Documentation/filesystems/ext3.txt
@@ -14,6 +14,11 @@ Options
 When mounting an ext3 filesystem, the following option are accepted:
 (*) == default
 
+ro                     Mount filesystem read only. Note that ext3 will replay
+                       the journal (and thus write to the partition) even when
+                       mounted "read only". Mount options "ro,noload" can be
+                       used to prevent writes to the filesystem.
+
 journal=update         Update the ext3 file system's journal to the current
                        format.
 
@@ -27,7 +32,9 @@ journal_dev=devnum    When the external journal device's major/minor numbers
                        identified through its new major/minor numbers encoded
                        in devnum.
 
-noload                 Don't load the journal on mounting.
+noload                 Don't load the journal on mounting. Note that this forces
+                       mount of inconsistent filesystem, which can lead to
+                       various problems.
 
 data=journal           All data are committed into the journal prior to being
                        written into the main file system.
@@ -92,9 +99,12 @@ nocheck
 
 debug                  Extra debugging information is sent to syslog.
 
-errors=remount-ro(*)   Remount the filesystem read-only on an error.
+errors=remount-ro      Remount the filesystem read-only on an error.
 errors=continue                Keep going on a filesystem error.
 errors=panic           Panic and halt the machine if an error occurs.
+                       (These mount options override the errors behavior
+                       specified in the superblock, which can be
+                       configured using tune2fs.)
 
 data_err=ignore(*)     Just print an error message if an error occurs
                        in a file data buffer in ordered mode.