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NFSv4: Clean up nfs_client_return_marked_delegations()

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Convert it to use the nfs_client_for_each_server() helper, and
make it more efficient by skipping delegations for inodes we
know are in the process of being freed. Also improve the efficiency
of the cursor by skipping delegations that are being freed.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
This commit is contained in:
Trond Myklebust 2020-02-27 08:29:02 -05:00
parent 3c9e502b59
commit af3b61bf61
1 changed files with 75 additions and 84 deletions
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159
fs/nfs/delegation.c
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@ -563,6 +563,79 @@ static bool nfs_delegation_need_return(struct nfs_delegation *delegation)
return ret;
}
static int nfs_server_return_marked_delegations(struct nfs_server *server,
void __always_unused *data)
{
struct nfs_delegation *delegation;
struct nfs_delegation *prev;
struct inode *inode;
struct inode *place_holder = NULL;
struct nfs_delegation *place_holder_deleg = NULL;
int err = 0;
restart:
/*
* To avoid quadratic looping we hold a reference
* to an inode place_holder. Each time we restart, we
* list delegation in the server from the delegations
* of that inode.
* prev is an RCU-protected pointer to a delegation which
* wasn't marked for return and might be a good choice for
* the next place_holder.
*/
prev = NULL;
delegation = NULL;
rcu_read_lock();
if (place_holder)
delegation = rcu_dereference(NFS_I(place_holder)->delegation);
if (!delegation || delegation != place_holder_deleg)
delegation = list_entry_rcu(server->delegations.next,
struct nfs_delegation, super_list);
list_for_each_entry_from_rcu(delegation, &server->delegations, super_list) {
struct inode *to_put = NULL;
if (test_bit(NFS_DELEGATION_INODE_FREEING, &delegation->flags))
continue;
if (!nfs_delegation_need_return(delegation)) {
if (nfs4_is_valid_delegation(delegation, 0))
prev = delegation;
continue;
}
if (prev) {
struct inode *tmp = nfs_delegation_grab_inode(prev);
if (tmp) {
to_put = place_holder;
place_holder = tmp;
place_holder_deleg = prev;
}
}
inode = nfs_delegation_grab_inode(delegation);
if (inode == NULL) {
rcu_read_unlock();
iput(to_put);
goto restart;
}
delegation = nfs_start_delegation_return_locked(NFS_I(inode));
rcu_read_unlock();
iput(to_put);
err = nfs_end_delegation_return(inode, delegation, 0);
iput(inode);
cond_resched();
if (!err)
goto restart;
set_bit(NFS4CLNT_DELEGRETURN, &server->nfs_client->cl_state);
goto out;
}
rcu_read_unlock();
out:
iput(place_holder);
return err;
}
/**
* nfs_client_return_marked_delegations - return previously marked delegations
* @clp: nfs_client to process
@ -575,90 +648,8 @@ static bool nfs_delegation_need_return(struct nfs_delegation *delegation)
*/
int nfs_client_return_marked_delegations(struct nfs_client *clp)
{
struct nfs_delegation *delegation;
struct nfs_delegation *prev;
struct nfs_server *server;
struct inode *inode;
struct inode *place_holder = NULL;
struct nfs_delegation *place_holder_deleg = NULL;
int err = 0;
restart:
/*
* To avoid quadratic looping we hold a reference
* to an inode place_holder. Each time we restart, we
* list nfs_servers from the server of that inode, and
* delegation in the server from the delegations of that
* inode.
* prev is an RCU-protected pointer to a delegation which
* wasn't marked for return and might be a good choice for
* the next place_holder.
*/
rcu_read_lock();
prev = NULL;
if (place_holder)
server = NFS_SERVER(place_holder);
else
server = list_entry_rcu(clp->cl_superblocks.next,
struct nfs_server, client_link);
list_for_each_entry_from_rcu(server, &clp->cl_superblocks, client_link) {
delegation = NULL;
if (place_holder && server == NFS_SERVER(place_holder))
delegation = rcu_dereference(NFS_I(place_holder)->delegation);
if (!delegation || delegation != place_holder_deleg)
delegation = list_entry_rcu(server->delegations.next,
struct nfs_delegation, super_list);
list_for_each_entry_from_rcu(delegation, &server->delegations, super_list) {
struct inode *to_put = NULL;
if (!nfs_delegation_need_return(delegation)) {
prev = delegation;
continue;
}
if (!nfs_sb_active(server->super))
break; /* continue in outer loop */
if (prev) {
struct inode *tmp;
tmp = nfs_delegation_grab_inode(prev);
if (tmp) {
to_put = place_holder;
place_holder = tmp;
place_holder_deleg = prev;
}
}
inode = nfs_delegation_grab_inode(delegation);
if (inode == NULL) {
rcu_read_unlock();
if (to_put)
iput(to_put);
nfs_sb_deactive(server->super);
goto restart;
}
delegation = nfs_start_delegation_return_locked(NFS_I(inode));
rcu_read_unlock();
if (to_put)
iput(to_put);
err = nfs_end_delegation_return(inode, delegation, 0);
iput(inode);
nfs_sb_deactive(server->super);
cond_resched();
if (!err)
goto restart;
set_bit(NFS4CLNT_DELEGRETURN, &clp->cl_state);
if (place_holder)
iput(place_holder);
return err;
}
}
rcu_read_unlock();
if (place_holder)
iput(place_holder);
return 0;
return nfs_client_for_each_server(clp,
nfs_server_return_marked_delegations, NULL);
}
/**