Messages in this thread | | | Date | Wed, 9 Aug 2006 11:27:40 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH 3/6] unlink: monitor i_nlink |
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On Wed, 09 Aug 2006 10:17:19 -0700 Dave Hansen <haveblue@us.ibm.com> wrote:
> On Wed, 2006-08-09 at 18:11 +0100, Christoph Hellwig wrote: > > On Wed, Aug 09, 2006 at 09:57:32AM -0700, Dave Hansen wrote: > > > > > > When a filesystem decrements i_nlink to zero, it means that a > > > write must be performed in order to drop the inode from the > > > filesystem. > > > > > > We're shortly going to have keep filesystems from being remounted > > > r/o between the time that this i_nlink decrement and that write > > > occurs. > > > > > > So, add a little helper function to do the decrements. We'll > > > tie into it in a bit to note when i_nlink hits zero. > > > > > > Signed-off-by: Dave Hansen <haveblue@us.ibm.com> > > > > Acked-by: Christoph Hellwig <hch@lst.de> > > > Note that we all (and especially Andrew :)) need to be carefull not to > > introduce unguarded i_nlink decrements again. Dave, you'll probably need > > to do another audit when you introduce the real functionality. > > Yup, I have my eyes on it. git and mm commits should help as well. >
A comprehensive way to do this sort of thing is to rename the field. We have >500 references, so one would do:
struct inode { ... union { unsigned int i_nlink; unsigned int i_nlink_use_the_accessors_please; } ... };
then, when everything in-tree is migrated, remove `i_nlink'.
It's a bit of a hassle, but it will give the most reliable result for both in-tree and out-of-tree filesystems.
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