On Fri, Oct 24, 2008 at 09:48:04AM +1100, Dave Chinner wrote: > On Thu, Oct 23, 2008 at 01:15:00PM +0200, Nick Piggin wrote: > > On Thu, Oct 23, 2008 at 10:44:16AM +0100, steve@xxxxxxxxxxx wrote: > > > Hi, > > > > > > On Thu, Oct 23, 2008 at 09:07:11AM +0200, Nick Piggin wrote: > > > > On Thu, Oct 23, 2008 at 10:07:15AM +1100, Dave Chinner wrote: > > > [snip] > > > > > > > > > You could do the same thing for metadata read operations. e.g. build > > > > > a large directory structure, then do read operations on it (readdir, > > > > > stat, etc) and inject errors into each of those. All filesystems > > > > > should return the (EIO) error to the application in this case. > > > > > > > > > > Those two cases should be pretty generic and deterministic - they > > > > > both avoid the difficult problem of determining what the response > > > > > to an I/O error during metadata modifcation should be.... > > > > > > > > Good suggestion. > > > > > > > > I'll see what I can do. I'm using the fault injection stuff, which I > > > > don't think can distinguish metadata, so I might just have to work > > > > out a bio flag or something we can send down to the block layer to > > > > distinguish. > > > > > > > > Thanks, > > > > Nick > > > > > > > > > > Don't we already have such a flag? I know that its not set in all > > > the correct places in GFS2 so far, but I've gradually been fixing > > > them to include BIO_RW_META where appropriate. > > > > That should probably work. It seems to be very incomplete (GFS2 > > being one of the few exceptions). Though adding more support in > > ext2 and buffer layer should be enough for me to start with, > > and shouldn't be too hard. I have a patch for (most of) buffer and ext2 btw. Seems to work OK. > I've posted patches to tag XFS metadata with BIO_RW_META in the > past, but that patch set had performance implications for different I/O > schedulers so it never went further than just a patch. If I Hmm, yes CFQ does do something with meta requests. It's a pity you can't just add the annotations and file bugs with CFQ if it hurts performance :P > leave all the BIO_RW_SYNC tagging for the metadata bios, then > a single line change to add BIO_RW_META should not have any > performance impact.... Sorry, I don't understand what you mean here. -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
