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authorTrond Myklebust2011-06-14 12:18:11 -0400
committerTrond Myklebust2011-07-12 13:40:28 -0400
commit47cb498e9316314e7e681f417135589195ad78a7 (patch)
tree2f48649123504119c8ab200300b919b040a0897b /fs/nfs
parente885de1a5bc9f46ef8f934c5a7602c89d2d51e8d (diff)
NFSv4.1: Clean ups for the device id cache
The fact that the global device id cache holds a reference to the nfs4_deviceid_node until it is invisible to rcu lookups implies that we can always assume that the reference count is non-zero in _find_get_deviceid. Also clean up nfs4_put_deviceid_node and the removal of the device id from the cache. Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Diffstat (limited to 'fs/nfs')
-rw-r--r--fs/nfs/pnfs.h1
-rw-r--r--fs/nfs/pnfs_dev.c44
2 files changed, 11 insertions, 34 deletions
diff --git a/fs/nfs/pnfs.h b/fs/nfs/pnfs.h
index dd54351ae6ac..1cfc96f8c45b 100644
--- a/fs/nfs/pnfs.h
+++ b/fs/nfs/pnfs.h
@@ -198,7 +198,6 @@ struct nfs4_deviceid_node {
void nfs4_print_deviceid(const struct nfs4_deviceid *dev_id);
struct nfs4_deviceid_node *nfs4_find_get_deviceid(const struct pnfs_layoutdriver_type *, const struct nfs_client *, const struct nfs4_deviceid *);
-struct nfs4_deviceid_node *nfs4_unhash_put_deviceid(const struct pnfs_layoutdriver_type *, const struct nfs_client *, const struct nfs4_deviceid *);
void nfs4_delete_deviceid(const struct pnfs_layoutdriver_type *, const struct nfs_client *, const struct nfs4_deviceid *);
void nfs4_init_deviceid_node(struct nfs4_deviceid_node *,
const struct pnfs_layoutdriver_type *,
diff --git a/fs/nfs/pnfs_dev.c b/fs/nfs/pnfs_dev.c
index f0f8e1e22f6c..fb9498d91f6a 100644
--- a/fs/nfs/pnfs_dev.c
+++ b/fs/nfs/pnfs_dev.c
@@ -100,8 +100,8 @@ _find_get_deviceid(const struct pnfs_layoutdriver_type *ld,
rcu_read_lock();
d = _lookup_deviceid(ld, clp, id, hash);
- if (d && !atomic_inc_not_zero(&d->ref))
- d = NULL;
+ if (d != NULL)
+ atomic_inc(&d->ref);
rcu_read_unlock();
return d;
}
@@ -115,15 +115,15 @@ nfs4_find_get_deviceid(const struct pnfs_layoutdriver_type *ld,
EXPORT_SYMBOL_GPL(nfs4_find_get_deviceid);
/*
- * Unhash and put deviceid
+ * Remove a deviceid from cache
*
* @clp nfs_client associated with deviceid
* @id the deviceid to unhash
*
* @ret the unhashed node, if found and dereferenced to zero, NULL otherwise.
*/
-struct nfs4_deviceid_node *
-nfs4_unhash_put_deviceid(const struct pnfs_layoutdriver_type *ld,
+void
+nfs4_delete_deviceid(const struct pnfs_layoutdriver_type *ld,
const struct nfs_client *clp, const struct nfs4_deviceid *id)
{
struct nfs4_deviceid_node *d;
@@ -134,7 +134,7 @@ nfs4_unhash_put_deviceid(const struct pnfs_layoutdriver_type *ld,
rcu_read_unlock();
if (!d) {
spin_unlock(&nfs4_deviceid_lock);
- return NULL;
+ return;
}
hlist_del_init_rcu(&d->node);
spin_unlock(&nfs4_deviceid_lock);
@@ -142,28 +142,7 @@ nfs4_unhash_put_deviceid(const struct pnfs_layoutdriver_type *ld,
/* balance the initial ref set in pnfs_insert_deviceid */
if (atomic_dec_and_test(&d->ref))
- return d;
-
- return NULL;
-}
-EXPORT_SYMBOL_GPL(nfs4_unhash_put_deviceid);
-
-/*
- * Delete a deviceid from cache
- *
- * @clp struct nfs_client qualifying the deviceid
- * @id deviceid to delete
- */
-void
-nfs4_delete_deviceid(const struct pnfs_layoutdriver_type *ld,
- const struct nfs_client *clp, const struct nfs4_deviceid *id)
-{
- struct nfs4_deviceid_node *d;
-
- d = nfs4_unhash_put_deviceid(ld, clp, id);
- if (!d)
- return;
- d->ld->free_deviceid_node(d);
+ d->ld->free_deviceid_node(d);
}
EXPORT_SYMBOL_GPL(nfs4_delete_deviceid);
@@ -221,16 +200,15 @@ EXPORT_SYMBOL_GPL(nfs4_insert_deviceid_node);
*
* @d deviceid node to put
*
- * @ret true iff the node was deleted
+ * return true iff the node was deleted
+ * Note that since the test for d->ref == 0 is sufficient to establish
+ * that the node is no longer hashed in the global device id cache.
*/
bool
nfs4_put_deviceid_node(struct nfs4_deviceid_node *d)
{
- if (!atomic_dec_and_lock(&d->ref, &nfs4_deviceid_lock))
+ if (!atomic_dec_and_test(&d->ref))
return false;
- hlist_del_init_rcu(&d->node);
- spin_unlock(&nfs4_deviceid_lock);
- synchronize_rcu();
d->ld->free_deviceid_node(d);
return true;
}