On Fri, Sep 01, 2017 at 09:37:26AM +1000, Dave Chinner wrote: > On Wed, Aug 30, 2017 at 10:44:43PM -0700, Darrick J. Wong wrote: > > On Thu, Aug 31, 2017 at 01:27:36PM +1000, Dave Chinner wrote: > > > On Wed, Aug 30, 2017 at 10:05:25PM -0500, Eric Sandeen wrote: > > > > On 8/30/17 9:43 PM, Dave Chinner wrote: > > > > > On Wed, Aug 30, 2017 at 05:10:09PM -0700, Darrick J. Wong wrote: > > > > >> On Wed, Aug 30, 2017 at 08:22:47AM +1000, Dave Chinner wrote: > > > > >>> On Tue, Aug 29, 2017 at 08:11:59AM -0700, Christoph Hellwig wrote: > > > > >>>> On Mon, Aug 21, 2017 at 01:13:33AM -0700, Christoph Hellwig wrote: > > > > >>>>> So what do you think of the version that adds real printks for > > > > >>>>> each condition including more details like the one verifier I > > > > >>>>> did below? Probably needs some unlikely annotations, though. > > > > >>>> > > > > >>>> Given that there was another resend of the series I'd be really > > > > >>>> curious about the answer to this? > > > > >>> > > > > >>> If we increase the size of the hexdump on error, then most of the > > > > >>> specific numbers in the print statements can be pulled from the > > > > >>> hexdump. And if the verifier tells us exactly what check failed, > > > > >>> we don't have to decode the entire hexdump to know what field was > > > > >>> out of band. > > > > >> > > > > >> How much do we increase the size of the hexdump? 64 -> 128? Or > > > > >> whatever the structure header size is? > > > > > > > > > > I choose 64 because it captured the primary header for most > > > > > structures for CRC enabled filesystems, so it would have > > > > > owner/crc/uuid/etc in it. I wasn't really trying to capture the > > > > > object specific metadata in it, but increasing to 128 bytes would > > > > > capture most of that block headers, too. Won't really help with > > > > > inodes, though, as the core is 176 bytes and the owner/crc stuff is > > > > > at the end.... > > > > > > > > > >> How about if xfs_error_level >= > > > > >> XFS_ERRORLEVEL_HIGH then we dump the entire buffer? > > > > > > > > > > Excellent idea. We can easily capture the entire output for > > > > > corruptions the users can easily trip over. Maybe put in the short > > > > > dump a line "turn error level up to 11 to get a full dump of the > > > > > corruption"? > > > > > > > > Yep, the thing about "more info only if you tune it" is that nobody > > > > will know to tune it. Unless you printk that info... > > > > > > > > Of course nobody will know what "turn error up ..." means, either. > > > > > > Sure, I was just paraphrasing how an error message might look. A > > > few quick coats of paint on the bikeshed will result in something > > > like: > > > > > > "If this is a recurring error, please set > > > /proc/sys/fs/xfs/error_level to ...." > > > > > > > Hm, at one point I had a patch to add object size to the > > > > xfs_buf_ops struct and print that many bytes, but can't find it now :/ > > > > (not that it was very complicated...) > > > > > > > > Anyway, point is making it vary with the size of the object wouldn't > > > > be too hard. > > > > > > Probably not, but it is complicated by the fact we have a couple of > > > different ways of dumping corruption errors. e.g. inode verifier > > > warnings are dumped through XFS_CORRUPTION_ERROR() rather than > > > xfs_verifier_error() as they are not buffer based verifiers. Other > > > things like log record CRC failures are hard coded to dump 32 bytes, > > > as is xlog_print_trans() on transaction overruns.... > > > > > > That's not a show stopper, but it would be nice to have consistent > > > behaviour across all the mechanisms we use to dump object data that > > > failed verification... > > > > /me wonders if it'd suffice just to add an xfs_params value in /proc, > > set its default to 128 bytes, and make the corruption reporters query > > the xfs_param. Then we could tell users to set it to some magic value > > (-1? 0?) to get the entire buffer. > > Let's avoid adding a new proc entries to configure error verbosity > when we already have a proc entry that controls error verbosity.... Fair enough. > > I just had another thought -- what if we always dump the whole buffer if > > the corruption would result in fs shutdown? > > How do you know that a verifier failure (or any specific call to > XFS_CORRUPTION_ERROR) is going to result in a filesystem shutdown? Nuts. For a minute there I thought that if we were trying to get/read a buffer we'd have assigned it to a transaction before calling the verifier, but that's not true. Oh well. I'll start with a simpler patch to increase the dump size if xfs_error_level is high. --D > Cheers, > > Dave. > -- > Dave Chinner > david@xxxxxxxxxxxxx > -- > To unsubscribe from this list: send the line "unsubscribe linux-xfs" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-xfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
