Re: [PATCH] write barriers for 2.4.x

Chris Mason
2002-02-15T22:04:31Z

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Ok, based on input from the scsi folks, reiserfs can't safely use the
ordered tags until some error handling changes are made in the scsi
drivers. Controllers that do write back caching (with battery backup) are
a different story, and since they can still benefit from the patch, I left
the scsi support in.

In this new version, filesystems can request either ordered tags (for scsi)
or just cache flushes (for ide). The idea is to have the ide flushing on
by default in the final version, since so many people have ide drives with
write back caching on.

reiserfs now has -o barrier_tag and -o barrier_flush mount options. In
both cases, if the device doesn't support the ordering, reiserfs backs down
to unordered writes.

The attached patch is against 2.4.18-pre9, but also works against rc1. The
main target for this will be making journaled filesystems safer for IDE
users, so ide testers would be appreciated.

-chris

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