NFSv4: Reduce the chances of an open_owner identifier collision
Currently we just use a 32-bit counter.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c
index 0f79d56..ab0b5ab 100644
--- a/fs/nfs/nfs4state.c
+++ b/fs/nfs/nfs4state.c
@@ -44,6 +44,7 @@
#include <linux/nfs_idmap.h>
#include <linux/kthread.h>
#include <linux/module.h>
+#include <linux/random.h>
#include <linux/workqueue.h>
#include <linux/bitops.h>
@@ -69,18 +70,14 @@
return status;
}
-u32
-nfs4_alloc_lockowner_id(struct nfs_client *clp)
-{
- return clp->cl_lockowner_id ++;
-}
-
struct rpc_cred *nfs4_get_renew_cred(struct nfs_client *clp)
{
struct nfs4_state_owner *sp;
+ struct rb_node *pos;
struct rpc_cred *cred = NULL;
- list_for_each_entry(sp, &clp->cl_state_owners, so_list) {
+ for (pos = rb_first(&clp->cl_state_owners); pos != NULL; pos = rb_next(pos)) {
+ sp = rb_entry(pos, struct nfs4_state_owner, so_client_node);
if (list_empty(&sp->so_states))
continue;
cred = get_rpccred(sp->so_cred);
@@ -92,32 +89,129 @@
static struct rpc_cred *nfs4_get_setclientid_cred(struct nfs_client *clp)
{
struct nfs4_state_owner *sp;
+ struct rb_node *pos;
- if (!list_empty(&clp->cl_state_owners)) {
- sp = list_entry(clp->cl_state_owners.next,
- struct nfs4_state_owner, so_list);
+ pos = rb_first(&clp->cl_state_owners);
+ if (pos != NULL) {
+ sp = rb_entry(pos, struct nfs4_state_owner, so_client_node);
return get_rpccred(sp->so_cred);
}
return NULL;
}
+static void nfs_alloc_unique_id(struct rb_root *root, struct nfs_unique_id *new,
+ __u64 minval, int maxbits)
+{
+ struct rb_node **p, *parent;
+ struct nfs_unique_id *pos;
+ __u64 mask = ~0ULL;
+
+ if (maxbits < 64)
+ mask = (1ULL << maxbits) - 1ULL;
+
+ /* Ensure distribution is more or less flat */
+ get_random_bytes(&new->id, sizeof(new->id));
+ new->id &= mask;
+ if (new->id < minval)
+ new->id += minval;
+retry:
+ p = &root->rb_node;
+ parent = NULL;
+
+ while (*p != NULL) {
+ parent = *p;
+ pos = rb_entry(parent, struct nfs_unique_id, rb_node);
+
+ if (new->id < pos->id)
+ p = &(*p)->rb_left;
+ else if (new->id > pos->id)
+ p = &(*p)->rb_right;
+ else
+ goto id_exists;
+ }
+ rb_link_node(&new->rb_node, parent, p);
+ rb_insert_color(&new->rb_node, root);
+ return;
+id_exists:
+ for (;;) {
+ new->id++;
+ if (new->id < minval || (new->id & mask) != new->id) {
+ new->id = minval;
+ break;
+ }
+ parent = rb_next(parent);
+ if (parent == NULL)
+ break;
+ pos = rb_entry(parent, struct nfs_unique_id, rb_node);
+ if (new->id < pos->id)
+ break;
+ }
+ goto retry;
+}
+
+static void nfs_free_unique_id(struct rb_root *root, struct nfs_unique_id *id)
+{
+ rb_erase(&id->rb_node, root);
+}
+
static struct nfs4_state_owner *
nfs4_find_state_owner(struct nfs_client *clp, struct rpc_cred *cred)
{
+ struct rb_node **p = &clp->cl_state_owners.rb_node,
+ *parent = NULL;
struct nfs4_state_owner *sp, *res = NULL;
- list_for_each_entry(sp, &clp->cl_state_owners, so_list) {
- if (sp->so_cred != cred)
- continue;
- atomic_inc(&sp->so_count);
- /* Move to the head of the list */
- list_move(&sp->so_list, &clp->cl_state_owners);
- res = sp;
- break;
+ while (*p != NULL) {
+ parent = *p;
+ sp = rb_entry(parent, struct nfs4_state_owner, so_client_node);
+
+ if (cred < sp->so_cred)
+ p = &parent->rb_left;
+ else if (cred > sp->so_cred)
+ p = &parent->rb_right;
+ else {
+ atomic_inc(&sp->so_count);
+ res = sp;
+ break;
+ }
}
return res;
}
+static struct nfs4_state_owner *
+nfs4_insert_state_owner(struct nfs_client *clp, struct nfs4_state_owner *new)
+{
+ struct rb_node **p = &clp->cl_state_owners.rb_node,
+ *parent = NULL;
+ struct nfs4_state_owner *sp;
+
+ while (*p != NULL) {
+ parent = *p;
+ sp = rb_entry(parent, struct nfs4_state_owner, so_client_node);
+
+ if (new->so_cred < sp->so_cred)
+ p = &parent->rb_left;
+ else if (new->so_cred > sp->so_cred)
+ p = &parent->rb_right;
+ else {
+ atomic_inc(&sp->so_count);
+ return sp;
+ }
+ }
+ nfs_alloc_unique_id(&clp->cl_openowner_id, &new->so_owner_id, 1, 64);
+ rb_link_node(&new->so_client_node, parent, p);
+ rb_insert_color(&new->so_client_node, &clp->cl_state_owners);
+ return new;
+}
+
+static void
+nfs4_remove_state_owner(struct nfs_client *clp, struct nfs4_state_owner *sp)
+{
+ if (!RB_EMPTY_NODE(&sp->so_client_node))
+ rb_erase(&sp->so_client_node, &clp->cl_state_owners);
+ nfs_free_unique_id(&clp->cl_openowner_id, &sp->so_owner_id);
+}
+
/*
* nfs4_alloc_state_owner(): this is called on the OPEN or CREATE path to
* create a new state_owner.
@@ -145,10 +239,14 @@
void
nfs4_drop_state_owner(struct nfs4_state_owner *sp)
{
- struct nfs_client *clp = sp->so_client;
- spin_lock(&clp->cl_lock);
- list_del_init(&sp->so_list);
- spin_unlock(&clp->cl_lock);
+ if (!RB_EMPTY_NODE(&sp->so_client_node)) {
+ struct nfs_client *clp = sp->so_client;
+
+ spin_lock(&clp->cl_lock);
+ rb_erase(&sp->so_client_node, &clp->cl_state_owners);
+ RB_CLEAR_NODE(&sp->so_client_node);
+ spin_unlock(&clp->cl_lock);
+ }
}
/*
@@ -160,22 +258,24 @@
struct nfs_client *clp = server->nfs_client;
struct nfs4_state_owner *sp, *new;
- new = nfs4_alloc_state_owner();
spin_lock(&clp->cl_lock);
sp = nfs4_find_state_owner(clp, cred);
- if (sp == NULL && new != NULL) {
- list_add(&new->so_list, &clp->cl_state_owners);
- new->so_client = clp;
- new->so_id = nfs4_alloc_lockowner_id(clp);
- new->so_cred = get_rpccred(cred);
- sp = new;
- new = NULL;
- }
spin_unlock(&clp->cl_lock);
- kfree(new);
if (sp != NULL)
return sp;
- return NULL;
+ new = nfs4_alloc_state_owner();
+ if (new == NULL)
+ return NULL;
+ new->so_client = clp;
+ new->so_cred = cred;
+ spin_lock(&clp->cl_lock);
+ sp = nfs4_insert_state_owner(clp, new);
+ spin_unlock(&clp->cl_lock);
+ if (sp == new)
+ get_rpccred(cred);
+ else
+ kfree(new);
+ return sp;
}
/*
@@ -189,7 +289,7 @@
if (!atomic_dec_and_lock(&sp->so_count, &clp->cl_lock))
return;
- list_del(&sp->so_list);
+ nfs4_remove_state_owner(clp, sp);
spin_unlock(&clp->cl_lock);
put_rpccred(cred);
kfree(sp);
@@ -386,12 +486,22 @@
atomic_set(&lsp->ls_count, 1);
lsp->ls_owner = fl_owner;
spin_lock(&clp->cl_lock);
- lsp->ls_id = nfs4_alloc_lockowner_id(clp);
+ nfs_alloc_unique_id(&clp->cl_lockowner_id, &lsp->ls_id, 1, 64);
spin_unlock(&clp->cl_lock);
INIT_LIST_HEAD(&lsp->ls_locks);
return lsp;
}
+static void nfs4_free_lock_state(struct nfs4_lock_state *lsp)
+{
+ struct nfs_client *clp = lsp->ls_state->owner->so_client;
+
+ spin_lock(&clp->cl_lock);
+ nfs_free_unique_id(&clp->cl_lockowner_id, &lsp->ls_id);
+ spin_unlock(&clp->cl_lock);
+ kfree(lsp);
+}
+
/*
* Return a compatible lock_state. If no initialized lock_state structure
* exists, return an uninitialized one.
@@ -421,7 +531,8 @@
return NULL;
}
spin_unlock(&state->state_lock);
- kfree(new);
+ if (new != NULL)
+ nfs4_free_lock_state(new);
return lsp;
}
@@ -442,7 +553,7 @@
if (list_empty(&state->lock_states))
clear_bit(LK_STATE_IN_USE, &state->flags);
spin_unlock(&state->state_lock);
- kfree(lsp);
+ nfs4_free_lock_state(lsp);
}
static void nfs4_fl_copy_lock(struct file_lock *dst, struct file_lock *src)
@@ -719,11 +830,13 @@
static void nfs4_state_mark_reclaim(struct nfs_client *clp)
{
struct nfs4_state_owner *sp;
+ struct rb_node *pos;
struct nfs4_state *state;
struct nfs4_lock_state *lock;
/* Reset all sequence ids to zero */
- list_for_each_entry(sp, &clp->cl_state_owners, so_list) {
+ for (pos = rb_first(&clp->cl_state_owners); pos != NULL; pos = rb_next(pos)) {
+ sp = rb_entry(pos, struct nfs4_state_owner, so_client_node);
sp->so_seqid.counter = 0;
sp->so_seqid.flags = 0;
spin_lock(&sp->so_lock);
@@ -742,6 +855,7 @@
{
struct nfs_client *clp = ptr;
struct nfs4_state_owner *sp;
+ struct rb_node *pos;
struct nfs4_state_recovery_ops *ops;
struct rpc_cred *cred;
int status = 0;
@@ -787,7 +901,8 @@
/* Mark all delegations for reclaim */
nfs_delegation_mark_reclaim(clp);
/* Note: list is protected by exclusive lock on cl->cl_sem */
- list_for_each_entry(sp, &clp->cl_state_owners, so_list) {
+ for (pos = rb_first(&clp->cl_state_owners); pos != NULL; pos = rb_next(pos)) {
+ sp = rb_entry(pos, struct nfs4_state_owner, so_client_node);
status = nfs4_reclaim_open_state(ops, sp);
if (status < 0) {
if (status == -NFS4ERR_NO_GRACE) {
