[PATCH] NFSv4: Clean up nfs4 lock state accounting

 Ensure that lock owner structures are not released prematurely.

 Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 79 insertions, 99 deletions

diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c
index 591ad1d5188..afe587d82f1 100644
--- a/fs/nfs/nfs4state.c
+++ b/fs/nfs/nfs4state.c
@@ -360,7 +360,7 @@ nfs4_alloc_open_state(void)
         atomic_set(&state->count, 1);
         INIT_LIST_HEAD(&state->lock_states);
         init_MUTEX(&state->lock_sema);
-        rwlock_init(&state->state_lock);
+        spin_lock_init(&state->state_lock);
         return state;
 }
 
@@ -542,16 +542,6 @@ __nfs4_find_lock_state(struct nfs4_state *state, fl_owner_t fl_owner)
         return NULL;
 }
 
-struct nfs4_lock_state *
-nfs4_find_lock_state(struct nfs4_state *state, fl_owner_t fl_owner)
-{
-        struct nfs4_lock_state *lsp;
-        read_lock(&state->state_lock);
-        lsp = __nfs4_find_lock_state(state, fl_owner);
-        read_unlock(&state->state_lock);
-        return lsp;
-}
-
 /*
  * Return a compatible lock_state. If no initialized lock_state structure
  * exists, return an uninitialized one.
@@ -568,14 +558,13 @@ static struct nfs4_lock_state *nfs4_alloc_lock_state(struct nfs4_state *state, f
                 return NULL;
         lsp->ls_flags = 0;
         lsp->ls_seqid = 0;      /* arbitrary */
-        lsp->ls_id = -1; 
         memset(lsp->ls_stateid.data, 0, sizeof(lsp->ls_stateid.data));
         atomic_set(&lsp->ls_count, 1);
         lsp->ls_owner = fl_owner;
-        INIT_LIST_HEAD(&lsp->ls_locks);
         spin_lock(&clp->cl_lock);
         lsp->ls_id = nfs4_alloc_lockowner_id(clp);
         spin_unlock(&clp->cl_lock);
+        INIT_LIST_HEAD(&lsp->ls_locks);
         return lsp;
 }
 
@@ -585,121 +574,112 @@ static struct nfs4_lock_state *nfs4_alloc_lock_state(struct nfs4_state *state, f
  *
  * The caller must be holding state->lock_sema and clp->cl_sem
  */
-struct nfs4_lock_state *nfs4_get_lock_state(struct nfs4_state *state, fl_owner_t owner)
+static struct nfs4_lock_state *nfs4_get_lock_state(struct nfs4_state *state, fl_owner_t owner)
 {
-        struct nfs4_lock_state * lsp;
+        struct nfs4_lock_state *lsp, *new = NULL;
         
-        lsp = nfs4_find_lock_state(state, owner);
-        if (lsp == NULL)
-                lsp = nfs4_alloc_lock_state(state, owner);
+        for(;;) {
+                spin_lock(&state->state_lock);
+                lsp = __nfs4_find_lock_state(state, owner);
+                if (lsp != NULL)
+                        break;
+                if (new != NULL) {
+                        new->ls_state = state;
+                        list_add(&new->ls_locks, &state->lock_states);
+                        set_bit(LK_STATE_IN_USE, &state->flags);
+                        lsp = new;
+                        new = NULL;
+                        break;
+                }
+                spin_unlock(&state->state_lock);
+                new = nfs4_alloc_lock_state(state, owner);
+                if (new == NULL)
+                        return NULL;
+        }
+        spin_unlock(&state->state_lock);
+        kfree(new);
         return lsp;
 }
 
 /*
- * Byte-range lock aware utility to initialize the stateid of read/write
- * requests.
+ * Release reference to lock_state, and free it if we see that
+ * it is no longer in use
  */
-void
-nfs4_copy_stateid(nfs4_stateid *dst, struct nfs4_state *state, fl_owner_t fl_owner)
+static void nfs4_put_lock_state(struct nfs4_lock_state *lsp)
 {
-        if (test_bit(LK_STATE_IN_USE, &state->flags)) {
-                struct nfs4_lock_state *lsp;
+        struct nfs4_state *state;
 
-                lsp = nfs4_find_lock_state(state, fl_owner);
-                if (lsp) {
-                        memcpy(dst, &lsp->ls_stateid, sizeof(*dst));
-                        nfs4_put_lock_state(lsp);
-                        return;
-                }
-        }
-        memcpy(dst, &state->stateid, sizeof(*dst));
+        if (lsp == NULL)
+                return;
+        state = lsp->ls_state;
+        if (!atomic_dec_and_lock(&lsp->ls_count, &state->state_lock))
+                return;
+        list_del(&lsp->ls_locks);
+        if (list_empty(&state->lock_states))
+                clear_bit(LK_STATE_IN_USE, &state->flags);
+        spin_unlock(&state->state_lock);
+        kfree(lsp);
 }
 
-/*
-* Called with state->lock_sema and clp->cl_sem held.
-*/
-void nfs4_increment_lock_seqid(int status, struct nfs4_lock_state *lsp)
+static void nfs4_fl_copy_lock(struct file_lock *dst, struct file_lock *src)
 {
-        if (status == NFS_OK || seqid_mutating_err(-status))
-                lsp->ls_seqid++;
-}
+        struct nfs4_lock_state *lsp = src->fl_u.nfs4_fl.owner;
 
-/* 
-* Check to see if the request lock (type FL_UNLK) effects the fl lock.
-*
-* fl and request must have the same posix owner
-*
-* return: 
-* 0 -> fl not effected by request
-* 1 -> fl consumed by request
-*/
+        dst->fl_u.nfs4_fl.owner = lsp;
+        atomic_inc(&lsp->ls_count);
+}
 
-static int
-nfs4_check_unlock(struct file_lock *fl, struct file_lock *request)
+static void nfs4_fl_release_lock(struct file_lock *fl)
 {
-        if (fl->fl_start >= request->fl_start && fl->fl_end <= request->fl_end)
-                return 1;
-        return 0;
+        nfs4_put_lock_state(fl->fl_u.nfs4_fl.owner);
 }
 
-/*
- * Post an initialized lock_state on the state->lock_states list.
- */
-void nfs4_notify_setlk(struct nfs4_state *state, struct file_lock *request, struct nfs4_lock_state *lsp)
+static struct file_lock_operations nfs4_fl_lock_ops = {
+        .fl_copy_lock = nfs4_fl_copy_lock,
+        .fl_release_private = nfs4_fl_release_lock,
+};
+
+int nfs4_set_lock_state(struct nfs4_state *state, struct file_lock *fl)
 {
-        if (!list_empty(&lsp->ls_locks))
-                return;
-        atomic_inc(&lsp->ls_count);
-        write_lock(&state->state_lock);
-        list_add(&lsp->ls_locks, &state->lock_states);
-        set_bit(LK_STATE_IN_USE, &state->flags);
-        write_unlock(&state->state_lock);
+        struct nfs4_lock_state *lsp;
+
+        if (fl->fl_ops != NULL)
+                return 0;
+        lsp = nfs4_get_lock_state(state, fl->fl_owner);
+        if (lsp == NULL)
+                return -ENOMEM;
+        fl->fl_u.nfs4_fl.owner = lsp;
+        fl->fl_ops = &nfs4_fl_lock_ops;
+        return 0;
 }
 
-/* 
- * to decide to 'reap' lock state:
- * 1) search i_flock for file_locks with fl.lock_state = to ls.
- * 2) determine if unlock will consume found lock. 
- *      if so, reap
- *
- *      else, don't reap.
- *
+/*
+ * Byte-range lock aware utility to initialize the stateid of read/write
+ * requests.
  */
-void
-nfs4_notify_unlck(struct nfs4_state *state, struct file_lock *request, struct nfs4_lock_state *lsp)
+void nfs4_copy_stateid(nfs4_stateid *dst, struct nfs4_state *state, fl_owner_t fl_owner)
 {
-        struct inode *inode = state->inode;
-        struct file_lock *fl;
+        struct nfs4_lock_state *lsp;
 
-        for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
-                if (!(fl->fl_flags & FL_POSIX))
-                        continue;
-                if (fl->fl_owner != lsp->ls_owner)
-                        continue;
-                /* Exit if we find at least one lock which is not consumed */
-                if (nfs4_check_unlock(fl,request) == 0)
-                        return;
-        }
+        memcpy(dst, &state->stateid, sizeof(*dst));
+        if (test_bit(LK_STATE_IN_USE, &state->flags) == 0)
+                return;
 
-        write_lock(&state->state_lock);
-        list_del_init(&lsp->ls_locks);
-        if (list_empty(&state->lock_states))
-                clear_bit(LK_STATE_IN_USE, &state->flags);
-        write_unlock(&state->state_lock);
+        spin_lock(&state->state_lock);
+        lsp = __nfs4_find_lock_state(state, fl_owner);
+        if (lsp != NULL && (lsp->ls_flags & NFS_LOCK_INITIALIZED) != 0)
+                memcpy(dst, &lsp->ls_stateid, sizeof(*dst));
+        spin_unlock(&state->state_lock);
         nfs4_put_lock_state(lsp);
 }
 
 /*
- * Release reference to lock_state, and free it if we see that
- * it is no longer in use
- */
-void
-nfs4_put_lock_state(struct nfs4_lock_state *lsp)
+* Called with state->lock_sema and clp->cl_sem held.
+*/
+void nfs4_increment_lock_seqid(int status, struct nfs4_lock_state *lsp)
 {
-        if (!atomic_dec_and_test(&lsp->ls_count))
-                return;
-        BUG_ON (!list_empty(&lsp->ls_locks));
-        kfree(lsp);
+        if (status == NFS_OK || seqid_mutating_err(-status))
+                lsp->ls_seqid++;
 }
 
 /*