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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>
This commit is contained in:
Trond Myklebust 2011-06-14 12:18:11 -04:00
parent e885de1a5b
commit 47cb498e93
2 changed files with 11 additions and 34 deletions
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1
fs/nfs/pnfs.h
View File

@ -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 *,

44
fs/nfs/pnfs_dev.c
View File

@ -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;
}