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SubjectRe: [PATCH 1/3] IMA: move read/write counters into struct inode
On Tue, Oct 19, 2010 at 01:11:33PM -0600, Matthew Wilcox wrote:
> Hm. Sounds like the same question that the file leases code needs
> answered. The important difference is that the leases code can just
> refuse to set a lease on inodes with multiple dentries.
> While my mind's on it ... Al, is this code even close to correct?
> if ((arg == F_RDLCK) && (atomic_read(&inode->i_writecount) > 0))
> goto out;
> if ((arg == F_WRLCK)
> && ((atomic_read(&dentry->d_count) > 1)
> || (atomic_read(&inode->i_count) > 1)))
> goto out;

No. This is complete junk; note that e.g. ls -lR will disrupt it, since
lstat(2) will bump dentry refcount. The first part is more or less OK;
the second makes no sense.

What is it trying to do? Note that the first part also doesn't make a lot
of sense, since you could be acquiring a write reference *right* *now*,
just as that check passes. And you could finish getting it before you get
to do anything else in generic_setlease().

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