Messages in this thread | | | Date | Sat, 29 Aug 2009 01:59:21 +0100 | From | Jamie Lokier <> | Subject | Re: adding proper O_SYNC/O_DSYNC, was Re: O_DIRECT and barriers |
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Jamie Lokier wrote: > Ulrich Drepper wrote: > > > - O_RSYNC basically means we need to commit atime updates before a > > > read returns, right? > > > > No, that's not it. > > > > O_RSYNC on its own just means the data is successfully transferred to > > the calling process (always the case). > > > > O_RSYNC|O_DSYNC means that if a read request hits data that is currently > > in a cache and not yet on the medium, then the write to medium is > > successful before the read succeeds. > > > > O_RSYNC|O_SYNC means the same plus the integrity of file meta > > information (access time etc). > > On several unixes, O_RSYNC means it will send the read to the > hardware, not relying on the cache. This can be used to verify the > data which was written earlier, whether by O_DSYNC or fdatasync.
I'm sure I read that in a couple of OS man pages, but I can't find it again. Maybe it was something more obscure than the mainstream unices; maybe I imagined it. Ho hum. For now, forget I said anythng.
-- Jamie
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