"Hiroshi Inoue" <Inoue@tpf.co.jp> writes:
> As far as I see,PostgreSQL doesn't call LockBuffer() before
> calling smgrwrite(). This seems to mean that smgrwrite()
> could write buffers to disk which are being changed by
> another backend. If the(another) backend was aborted by
> some reason the buffer page would remain half-changed.
Hmm ... looks fishy to me too. Seems like we ought to hold
BUFFER_LOCK_SHARE on the buffer while dumping it out. It
wouldn't matter under normal circumstances, but as you say
there could be trouble if the other backend crashed before
it could mark the buffer dirty again, or if we had a system
crash before the dirtied page got written again.
Vadim, what do you think?
regards, tom lane