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Message-ID: <baaef4711002240826t1b447662yf66c980dea1d9d00@mail.gmail.com> Date: Wed, 24 Feb 2010 17:26:37 +0100 From: Camille Moncelier <pix@...life.org> To: "linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>, ext4 development <linux-ext4@...r.kernel.org> Cc: Jan Kara <jack@...e.cz> Subject: Re: [ext3] Changes to block device after an ext3 mount point has been remounted readonly > Theoretically some pages may exist after rw=>ro remount > because of generic race between write/sync, And they will be written > in by writepage if page already has buffers. This not happen in ext4 > because. Each time it try to perform writepages it try to start_journal > and this result in EROFS. > The race bug will be closed some day but new one may appear again. > > Let's be honest and change ext3 writepage like follows: > - check ROFS flag inside write page > - dump writepage's errors. > > I think I don't understand correctly your patch. For me it seems that when an ext3 filesystem is remounted ro, some data may not have been written to disk right ? But as far as I understand some writes are performed on the journal on remount-ro, before the ro flag is set. So if writepage comes to play and write data to disk it my have to update the journal again, no ? If not it would mean that the journal would reference data that aren't available on disk ? Last question, would it be hard to implement a patch that trigger writepage and wait for completion when remounting read-only (I have no expertise on filesystems in general, but I tried my best to understand the ext3 driver) -- Camille Moncelier http://devlife.org/ If Java had true garbage collection, most programs would delete themselves upon execution. -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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