Messages in this thread | | | From | Petr Tesarik <> | Subject | Re: ext4 features (salvage) | Date | Tue, 04 Jul 2006 13:55:54 +0200 |
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On Tue, 2006-07-04 at 13:35 +0200, Peter Zijlstra wrote: > On Tue, 2006-07-04 at 11:22 +0200, Petr Tesarik wrote: > > Yes and no. A simple mv is better done in userspace, but what I'd > > _really_ appreciate would be a true kernel salvage (similar to the way > > NetWare does things). That means marking the file as deleted in the > > directory, marking its blocks as deleted but avoiding the use of those > > blocks. The kernel would then prefer allocating new blocks from > > elsewhere but once the filesystem runs out of space, it would start > > allocating from the deleted files area and marking the blocks as well as > > the corresponding files purged. > > > > Salvaging files would be done with a separate tool. Of course, if you > > delete more files with the same name in the same directory, you'd need > > to tell that tool which one of them you want to salvage. Yes, I really > > mean you'd have more than one deleted file with the same name in the > > directory. > > Wouldn't such a scheme interfere with the block allocator algorithms, > and hence increase the risk of fragmentation? Schemes like this realy > put my hairs on end,
Yes, they would interfere. That's why I'm not proposing to add them to ext4 in the first place.
> 1) if you don't want to lose your data, make backups;
Generally, I agree.
> 2) if I mean to delete a file, I want it gone proper. Silently keeping > it about is not unix like;
Yes, this is a problem. Although you would of course have a tool for purging the files unconditionally, some programs may need the assumption that an unlinked file is gone forever.
Regarding the second clause, well, Linux is not Unix-like in many respects and we want it like that. That's a weak argument.
> 3) don't aid third parties in recovering your removed data. If I want > them to have it I'll give it to them.
See 2. Explicit purging is of course possible. (Novell Netware also had a "purge" command.)
Anyway, it seems that there is some functionality which many users want but which can't be provided in user space:
- if files are moved to the recycle-bin-or-whatever-you-call-it, their size is added to disk free space and - automatically purging least recently deleted files.
Regards, Petr Tesarik - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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