ext4: add an option to control error handling on file data

If the journal doesn't abort when it gets an IO error in file data
blocks, the file data corruption will spread silently.  Because
most of applications and commands do buffered writes without fsync(),
they don't notice the IO error.  It's scary for mission critical
systems.  On the other hand, if the journal aborts whenever it gets
an IO error in file data blocks, the system will easily become
inoperable.  So this patch introduces a filesystem option to
determine whether it aborts the journal or just call printk() when
it gets an IO error in file data.

If you mount an ext4 fs with data_err=abort option, it aborts on file
data write error.  If you mount it with data_err=ignore, it doesn't
abort, just call printk().  data_err=ignore is the default.

Here is the corresponding patch of the ext3 version:
http://kerneltrap.org/mailarchive/linux-kernel/2008/9/9/3239374

Signed-off-by: Hidehiro Kawai <hidehiro.kawai.ez@hitachi.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

1 files changed, 3 insertions, 0 deletions

diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h
index c9e7d781db31..d2e91ea998fd 100644
--- a/include/linux/jbd2.h
+++ b/include/linux/jbd2.h
@@ -967,6 +967,9 @@ struct journal_s
 #define JBD2_FLUSHED    0x008   /* The journal superblock has been flushed */
 #define JBD2_LOADED     0x010   /* The journal superblock has been loaded */
 #define JBD2_BARRIER    0x020   /* Use IDE barriers */
+#define JBD2_ABORT_ON_SYNCDATA_ERR      0x040   /* Abort the journal on file
+                                                 * data write error in ordered
+                                                 * mode */
 
 /*
  * Function declarations for the journaling transaction and buffer