Messages in this thread | | | Date | Fri, 14 Dec 2001 10:06:38 -0500 | From | dmeyer@dmeyer ... | Subject | Re: reiser4 (was Re: [PATCH] Revised extended attributes interface) |
| |
In article <3C19DE41.6000507@namesys.com> you write: > Brad Boyer wrote: > >In particular, the files in the snapshot keep > >the same inode number as the actual file. Just remember that clever > >solutions that almost fit the traditional model can have strange > >results over time. > > Can you detail the problem?
Anything that uses something like file1.st_dev==file2.st_dev && file1.st_ino==file2.st_ino to decide if two filenames point to the same file can get terribly confused. For example,
$ ls -li .snapshot/hourly.0/.zshrc .zshrc 1411878 -rw-r--r-- 1 1247 Mar 19 2001 .snapshot/hourly.0/.zshrc 1411878 -rw-r--r-- 1 1248 Dec 14 09:51 .zshrc
Clearly, the file has been modified since the hourly.0 snapshot; however
$ cp .snapshot/hourly.0/.zshrc .zshrc cp: `.snapshot/hourly.0/.zshrc' and `.zshrc' are the same file
you can't copy the snapshot on top of the current version, since they have the same inode number. A somewhat contrived example, perhaps, but I have been bitten by something similar in the real world. One of the things I would like to be able to do with a snapshot is to open a file in emacs, open a snapshot in another window, and compare the two files with ediff. And you can't; emacs treats the original and the snapshot as if they were the same file - just like cp does - even though the file contents are different.
-- Dave Meyer dmeyer@dmeyer.net - 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/
| |