Messages in this thread | | | Date | Sun, 2 Apr 2006 19:43:15 +0100 | From | Al Viro <> | Subject | Re: RFC replace some locking of i_sem wiht atomic_t |
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On Sun, Apr 02, 2006 at 11:01:30AM -0700, Joshua Hudson wrote: > Herein lies the problem with the current locking scheme: > 1. rename locks target if it exists, but target may be created by > link() immediately > after the check&lock procedure. > 2. The target of link() is completely unprotected.
3. You have failed to RTFS or RTFM.
> Against ext2, this can result in a corrupted filesystem (two directory > entries with > the same name) by a three-way race between two instances of link() and one > unlink().
Not really.
> 1. Both instances of link are started with target being the same name > in the same directory. > 2. unlink() is started on a different name in the same directory. > 3. link() 1 doesn't find a free slot in the first page, moves to the second. > *rescheduled before locking second page* > 4. unlink() finds target in first page, removes it. > 5. link() 2 finds free slot in first page, creates entry, finishes > 6. link() 1 continues, finds space in second page, creates entry
And this is BS, since link() _does_ grab ->i_sem on directory it modifies. So does unlink(). - 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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