On Thu, Nov 08, 2012 at 05:46:42PM -0600, Ben Myers wrote: > Hey Dave, > > On Fri, Nov 09, 2012 at 10:06:49AM +1100, Dave Chinner wrote: > > On Thu, Nov 08, 2012 at 04:23:16PM -0600, Andrew Dahl wrote: > > > xfs_tosspages() takes a closed interval as an argument, take > > > this into account when rounding down to the last byte of the > > > last complete page. If the request consists of a single > > > partial page, there will be nothing to toss. > > > > > > Signed-off-by: Andrew Dahl <adahl@xxxxxxx> > > > > > > --- > > ... > > > So the change is good. > > > > However, there's a bigger issue here. We've planned to remove these > > wrappers for a long time, just never got around to doing it. Seeing > > as there is a bug in this wrapper and it needs to be fixed, now > > seems like the right time to remove it. > > The removal of the wrappers would not be appropriate for -stable. This fix > needs to go in separately from any refactoring so that it can be pulled back > within the rules outlined in Documentation/stable_kernel_rules.txt. You're acting like I've never read those rules before. I know exactly what they say, and patch that removes a busted helper is well and truly within the scope of a stable backport. Quoting rules at me like I'm a newbie only serves to annoy me.... As it is, looking at what xfs_tosspages is supposed to be doing, calling truncate_inode_pages_range() is actually the wrong thing to do. We should be calling truncate_pagecache_range(), because we should be unmapping pages before truncating them away. And for that same reason, xfs_flushinvalidate() is also wrong and broken. That is, the call in xfs_swap_extents() changes to: - xfs_tosspages(ip, 0, -1, FI_REMAPF); + truncate_pagecache_range(VFS_I(ip), 0, -1); And the one in xfs_change_file_space becomes: - xfs_tosspages(ip, startoffset, startoffset + bf->l_len, 0); + truncate_pagecache_range(VFS_I(ip), startoffset, + startoffset + bf->l_len); and xfs_tosspages() goes away. That's a far better fix for the problem than what has been proposed, IMO, and in no way is inappropriate for -stable. As it is, I wouldn't even consider this a fix that is needed for stable kernels - XFS_IOC_ZERO is an obscure interface, and xfs_swap_extents works just fine as it stands.... .... > > > prealloc_type |= XFS_BMAPI_CONVERT; > > > - xfs_tosspages(ip, startoffset, startoffset + bf->l_len, 0); > > > + xfs_tosspages(ip, startoffset, bf->l_len ? startoffset + llen : -1, 0); > > > /* FALLTHRU */ > > > case XFS_IOC_RESVSP: > > > case XFS_IOC_RESVSP64: > > > > What's this hunk for? Indeed, one of the first things that the > > xfs_alloc_file_space() checks is this: > > > > if (len <= 0) > > return XFS_ERROR(EINVAL); > > > > xfs_free_file_space() does the same check, so it is invalid to pass > > a bf_len <= 0 for any of these specific functions. Hence this change > > is wrong regardless of what the comment on the struct xfs_flock64_t > > says - preallocation and hole punch operations must have a positive > > length associated with them. > > Andrew, if you agree that this second change is unnecessary go ahead and remove > it and repost. Otherwise, I didn't say it was unnecessary - I said it was wrong. We shouldn't even be getting as far as the xfs_tosspages() call if bf_len is zero or negative. That's the bug that needs fixing in this function. Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
