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ceph: handle the case where a dentry has been renamed on outstanding req

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It's possible for us to issue a lookup to revalidate a dentry
concurrently with a rename. If done in the right order, then we could
end up processing dentry info in the reply that no longer reflects the
state of the dentry.

If req->r_dentry->d_name differs from the one in the trace, then just
ignore the trace in the reply. We only need to do this however if the
parent's i_rwsem is not held.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: "Yan, Zheng" <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
This commit is contained in:
Jeff Layton 2019-04-15 12:00:42 -04:00 committed by Ilya Dryomov
parent 76a495d666
commit 4b82228700
1 changed files with 15 additions and 1 deletions
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16
fs/ceph/inode.c
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@ -1163,6 +1163,19 @@ static int splice_dentry(struct dentry **pdn, struct inode *in)
return 0;
}
static int d_name_cmp(struct dentry *dentry, const char *name, size_t len)
{
int ret;
/* take d_lock to ensure dentry->d_name stability */
spin_lock(&dentry->d_lock);
ret = dentry->d_name.len - len;
if (!ret)
ret = memcmp(dentry->d_name.name, name, len);
spin_unlock(&dentry->d_lock);
return ret;
}
/*
* Incorporate results into the local cache. This is either just
* one inode, or a directory, dentry, and possibly linked-to inode (e.g.,
@ -1412,7 +1425,8 @@ retry_lookup:
err = splice_dentry(&req->r_dentry, in);
if (err < 0)
goto done;
} else if (rinfo->head->is_dentry) {
} else if (rinfo->head->is_dentry &&
!d_name_cmp(req->r_dentry, rinfo->dname, rinfo->dname_len)) {
struct ceph_vino *ptvino = NULL;
if ((le32_to_cpu(rinfo->diri.in->cap.caps) & CEPH_CAP_FILE_SHARED) ||