[PATCH] Avoid console spam with ext3 aborted journal.

Avoid console spam with ext3 aborted journal.

ext3 usually reports error conditions that it detects in its environment.
But when its journal gets aborted due to such errors, it can sometimes
continue to report that condition forever, spamming the console to such
an extent that the initial first cause of the journal abort can be lost.

When the journal aborts, we put the filesystem into readonly mode.  Most
subsequent filesystem operations will get rejected immediately by checks
for MS_RDONLY either in the filesystem or in the VFS.  But some paths do
not have such checks --- for example, if we continue to write to a file
handle that was opened before the fs went readonly.  (We only check for
the ROFS condition when the file is first opened.)  In these cases, we
can continue to generate log errors similar to

EXT3-fs error (device $DEV) in start_transaction: Journal has aborted

for each subsequent write.

There is really no point in generating these er...