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Neil Brown 28ae094c62 ext3 can fail badly when device stops accepting BIO_RW_BARRIER requests ... Some devices - notably dm and md - can change their behaviour in response to BIO_RW_BARRIER requests. They might start out accepting such requests but on reconfiguration, they find out that they cannot any more. ext3 (and other filesystems) deal with this by always testing if BIO_RW_BARRIER requests fail with EOPNOTSUPP, and retrying the write requests without the barrier (probably after waiting for any pending writes to complete). However there is a bug in the handling for this for ext3. When ext3 (jbd actually) decides to submit a BIO_RW_BARRIER request, it sets the buffer_ordered flag on the buffer head. If the request completes successfully, the flag STAYS SET. Other code might then write the same buffer_head after the device has been reconfigured to not accept barriers. This write will then fail, but the "other code" is not ready to handle EOPNOTSUPP errors and the error will be treated as fatal. This can be seen without having to reconfigure a device at exactly the wrong time by putting: if (buffer_ordered(bh)) printk("OH DEAR, and ordered buffer\n"); in the while loop in "commit phase 5" of journal_commit_transaction. If it ever prints the "OH DEAR ..." message (as it does sometimes for me), then that request could (in different circumstances) have failed with EOPNOTSUPP, but that isn't tested for. My proposed fix is to clear the buffer_ordered flag after it has been used, as in the following patch. Signed-off-by: Neil Brown <neilb@suse.de> Cc: <linux-ext4@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>		17 years ago
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Makefile	Linux-2.6.12-rc2	20 years ago
checkpoint.c	spinlock: lockbreak cleanup	17 years ago
commit.c	ext3 can fail badly when device stops accepting BIO_RW_BARRIER requests	17 years ago
journal.c	make jbd/journal.c:__journal_abort_hard() static	17 years ago
recovery.c	BKL-removal: remove incorrect comment refering to lock_kernel() from jbd/jbd2	17 years ago
revoke.c	Group short-lived and reclaimable kernel allocations	18 years ago
transaction.c	jbd: do not try lock_acquire after handle made invalid	17 years ago