On Jan 3, 2005, at 7:07 PM, Gregor Mosheh wrote:
--- David Kelly <[EMAIL PROTECTED]> wrote:
Another goof is for root to "write" to an unmounted filesystem. Later when the filesystem is mounted the written files are hidden yet still consume space on the fs containing the mount point (usually /).
Could you explain how this happens (or point me to a doc)? Do you mean something like "tar cvf /dev/ad0s1a"?
Guessing you quoted the wrong paragraph for the question.
As for tar, yes, "tar -cvf /dev/baddevicename myfiles" will happily create a file (not device) named /dev/baddevicename and write the contents of myfiles into it. Iff you have write permission on /dev/. Its no different than "tar -cvf myfiles.tar myfiles" other than you tried to hit a device but created a file instead.
As for what I was writing about consider the case where one is running single user and /usr is not yet mounted. A directory named /usr exists. Nothing is preventing root from writing in the /usr directory. This will consume space on / but no longer exist in file namespace once a filesystem is mounted on top of the /usr directory. Files are still there but you can't get to them.
Does that cause fs corruption? Would fsck reclaim that space?
No corruption. Fsck is perfectly happy with it and won't change a thing. The stuff hidden under the mount point is still there. The only way to get at it is to umount the fs on top and then the previous contents of /usr reappear. Assuming of course that /usr actually had files underneath.
Go read the manpage for mount. Search for "union". Its talking about the same thing as above only a union mount appends the underlying namespace at the end of the mounted filesystem's namespace. Without "union" the underlying namespace is unreachable.
-- David Kelly N4HHE, [EMAIL PROTECTED] ======================================================================== Whom computers would destroy, they must first drive mad.
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