2006-10-05 22:48:28

by Andrew Morton

[permalink] [raw]
Subject: + ext3-errors-behaviour-fix.patch added to -mm tree

The patch titled

ext3: errors behaviour fix

has been added to the -mm tree. Its filename is


See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this

Subject: ext3: errors behaviour fix
From: Dmitry Mishin <[email protected]>

Current error behaviour for ext2 and ext3 filesystems does not fully
correspond to the documentation and should be fixed.

According to man 8 mount, ext2 and ext3 file systems allow to set one of 3
different on-errors behaviours:

---- start of quote man 8 mount ----

errors=continue / errors=remount-ro / errors=panic

Define the behaviour when an error is encountered. (Either ignore
errors and just mark the file system erroneous and continue, or remount
the file system read-only, or panic and halt the system.) The default is
set in the filesystem superblock, and can be changed using tune2fs(8).

---- end of quote ----

However EXT3_ERRORS_CONTINUE is not read from the superblock, and thus
ERRORS_CONT is not saved on the sbi->s_mount_opt. It leads to the incorrect
handle of errors on ext3.

Then we've checked corresponding code in ext2 and discovered that it is buggy
as well:

- EXT2_ERRORS_CONTINUE is not read from the superblock (the same);

- parse_option() does not clean the alternative values and thus something
like (ERRORS_CONT|ERRORS_RO) can be set;

- if options are omitted, parse_option() does not set any of these options.

Therefore it is possible to set any combination of these options on the ext2:

- none of them may be set: EXT2_ERRORS_CONTINUE on superblock / empty mount

- any of them may be set using mount options;

- 2 any options may be set: by using EXT2_ERRORS_RO/EXT2_ERRORS_PANIC on the
superblock and other value in mount options;

- and finally all three options may be set by adding third option in remount.

Currently ext2 uses these values only in ext2_error() and it is not leading to
any noticeable troubles. However somebody may be discouraged when he will try
to workaround EXT2_ERRORS_PANIC on the superblock by using errors=continue in
mount options.

This patch:

EXT3_ERRORS_CONTINUE should be taken from the superblock as default value for
error behaviour.

Signed-off-by: Dmitry Mishin <[email protected]>
Acked-by: Vasily Averin <[email protected]>
Acked-by: Kirill Korotaev <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

fs/ext3/super.c | 2 ++
1 files changed, 2 insertions(+)

diff -puN fs/ext3/super.c~ext3-errors-behaviour-fix fs/ext3/super.c
--- a/fs/ext3/super.c~ext3-errors-behaviour-fix
+++ a/fs/ext3/super.c
@@ -1470,6 +1470,8 @@ static int ext3_fill_super (struct super
set_opt(sbi->s_mount_opt, ERRORS_PANIC);
else if (le16_to_cpu(sbi->s_es->s_errors) == EXT3_ERRORS_RO)
set_opt(sbi->s_mount_opt, ERRORS_RO);
+ else
+ set_opt(sbi->s_mount_opt, ERRORS_CONT);

sbi->s_resuid = le16_to_cpu(es->s_def_resuid);
sbi->s_resgid = le16_to_cpu(es->s_def_resgid);
diff -puN /dev/null /dev/null

Patches currently in -mm which might be from [email protected] are