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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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