On Mon, Jul 17, 2017 at 09:25:57PM -0500, Eric Sandeen wrote: > > > On 07/17/2017 09:20 PM, Dave Chinner wrote: > > On Mon, Jul 17, 2017 at 03:51:50PM -0500, Eric Sandeen wrote: > >> > >> > >> On 06/28/2017 11:01 PM, Eric Sandeen wrote: > >>>> I guess there's also the problem that if inodesize != 512 then what are > >>>> we targeting, anyway? If inodesize = 256 then we can only hit > >>>> even-numbered inodes (not so bad) but if inodesize > 512 then do we jump > >>>> back to wherever the inode starts? Or just give the user what they > >>>> asked for, even if it's garbage? > >>> Oh, hum. Right, big inodes.... > >>> > >>> So I'm trying to go from disk location to inode number, but the current > >>> disk location may not even be the start of an inode. Hell. Well, I'm > >>> sure I could craft a test to disallow "type inode" if the current location > >>> cannot be on an inode boundary. But is that too clever? Should the > >>> debug tool just do what the user asks? > >>> > >>>> (FWIW I was fine with xfs_db being dumb and giving you exactly what you > >>>> point it at, even if that makes no sense. :P) > >>> yeah, if you do "daddr 0" "type agf" it'll squawk, too, so it's fine to > >>> do the dumb user's bidding... > >> > >> So as I have it today, issuing "type inode" will actually re-align you > >> to an inode offset even if you're not on one: > >> > >> xfs_db> sb 0 > >> xfs_db> addr rootino > >> xfs_db> daddr > >> current daddr is 128 > >> xfs_db> daddr 129 > >> xfs_db> type inode > >> xfs_db> daddr > >> current daddr is 128 > >> xfs_db> > >> > >> good? bad? indifferent? I'm thinking "bad" but we have no mechanism to > >> read a batch of inodes in xfs_db other than by passing in a legit inode number. > >> > >> And we have no mechanism to read only a /single/ inode... > >> > >> Maybe print a warning about the re-alignment and carry on? > > > > xfs_db is meant to be a developer tool, not idiot-proof. :P > > > > i.e. some knowledge of the layout of the metadata you are trying > > to examine is expected. I would not like xfs_db to change the daddr > > I've specified simply because I tried to parse it as the wrong > > object type.... > > That would be my first preference as well, but all the infrastructure > we have for gathering up an inode from a cluster is predicated on being > given an inode nr, not a daddr. I could hack the heck out of it and refactor > it to allow clusters starting on arbitrary sectors, I guess, but I'm not > sure it's worth it. For now it seems more useful than not to be able to > switch from a daddr to an inode (which possibly /contains/ rather than starts > at that daddr ...) That's what already have a mechanism for converting arbitrary daddrs to a correctly aligned inode number: xfs_db> convert daddr <daddr> inode 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
