orangefs: bufmap rewrite

new waiting-for-slot logics:
	* make request for slot wait for bufmap to be set up if it
comes before it's installed *OR* while it's running down
	* make closing control device wait for all slots to be freed
	* waiting itself rewritten to (open-coded) analogues of wait_event_...
primitives - we would need wait_event_locked() and, pardon an obscenely
long name, wait_event_interruptible_exclusive_timeout_locked().
	* we never wait for more than slot_timeout_secs in total and,
if during the wait the daemon goes away, we only allow
ORANGEFS_BUFMAP_WAIT_TIMEOUT_SECS for it to come back.
	* (cosmetical) bitmap is used instead of an array of zeroes and ones
	* old (and only reached if we are about to corrupt memory) waiting
for daemon restart in service_operation() removed.

[Martin's fixes folded]

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Mike Marshall <hubcap@omnibond.com>

4 files changed, 174 insertions, 247 deletions

diff --git a/fs/orangefs/devorangefs-req.c b/fs/orangefs/devorangefs-req.c
index 6a7df1204bfc..790855a72e32 100644
--- a/fs/orangefs/devorangefs-req.c
+++ b/fs/orangefs/devorangefs-req.c
@@ -508,8 +508,7 @@ static int orangefs_devreq_release(struct inode *inode, struct file *file)
                      __func__);
 
         mutex_lock(&devreq_mutex);
-        if (orangefs_get_bufmap_init())
-                orangefs_bufmap_finalize();
+        orangefs_bufmap_finalize();
 
         open_access_count = -1;
 
@@ -527,6 +526,9 @@ static int orangefs_devreq_release(struct inode *inode, struct file *file)
          * them as purged and wake them up
          */
         purge_inprogress_ops();
+
+        orangefs_bufmap_run_down();
+
         gossip_debug(GOSSIP_DEV_DEBUG,
                      "pvfs2-client-core: device close complete\n");
         open_access_count = 0;
@@ -607,13 +609,8 @@ static long dispatch_ioctl_command(unsigned int command, unsigned long arg)
                                      (struct ORANGEFS_dev_map_desc __user *)
                                      arg,
                                      sizeof(struct ORANGEFS_dev_map_desc));
-                if (orangefs_get_bufmap_init()) {
-                        return -EINVAL;
-                } else {
-                        return ret ?
-                               -EIO :
-                               orangefs_bufmap_initialize(&user_desc);
-                }
+                /* WTF -EIO and not -EFAULT? */
+                return ret ? -EIO : orangefs_bufmap_initialize(&user_desc);
         case ORANGEFS_DEV_REMOUNT_ALL:
                 gossip_debug(GOSSIP_DEV_DEBUG,
                              "%s: got ORANGEFS_DEV_REMOUNT_ALL\n",
diff --git a/fs/orangefs/orangefs-bufmap.c b/fs/orangefs/orangefs-bufmap.c
index cd484665bf72..96faf4ee6529 100644
--- a/fs/orangefs/orangefs-bufmap.c
+++ b/fs/orangefs/orangefs-bufmap.c
@@ -7,7 +7,133 @@
 #include "orangefs-kernel.h"
 #include "orangefs-bufmap.h"
 
-DECLARE_WAIT_QUEUE_HEAD(orangefs_bufmap_init_waitq);
+struct slot_map {
+        int c;
+        wait_queue_head_t q;
+        int count;
+        unsigned long *map;
+};
+
+static struct slot_map rw_map = {
+        .c = -1,
+        .q = __WAIT_QUEUE_HEAD_INITIALIZER(rw_map.q)
+};
+static struct slot_map readdir_map = {
+        .c = -1,
+        .q = __WAIT_QUEUE_HEAD_INITIALIZER(readdir_map.q)
+};
+
+
+static void install(struct slot_map *m, int count, unsigned long *map)
+{
+        spin_lock(&m->q.lock);
+        m->c = m->count = count;
+        m->map = map;
+        wake_up_all_locked(&m->q);
+        spin_unlock(&m->q.lock);
+}
+
+static void mark_killed(struct slot_map *m)
+{
+        spin_lock(&m->q.lock);
+        m->c -= m->count + 1;
+        spin_unlock(&m->q.lock);
+}
+
+static void run_down(struct slot_map *m)
+{
+        DEFINE_WAIT(wait);
+        spin_lock(&m->q.lock);
+        if (m->c != -1) {
+                for (;;) {
+                        if (likely(list_empty(&wait.task_list)))
+                                __add_wait_queue_tail(&m->q, &wait);
+                        set_current_state(TASK_UNINTERRUPTIBLE);
+
+                        if (m->c == -1)
+                                break;
+
+                        spin_unlock(&m->q.lock);
+                        schedule();
+                        spin_lock(&m->q.lock);
+                }
+                __remove_wait_queue(&m->q, &wait);
+                __set_current_state(TASK_RUNNING);
+        }
+        m->map = NULL;
+        spin_unlock(&m->q.lock);
+}
+
+static void put(struct slot_map *m, int slot)
+{
+        int v;
+        spin_lock(&m->q.lock);
+        __clear_bit(slot, m->map);
+        v = ++m->c;
+        if (unlikely(v == 1))   /* no free slots -> one free slot */
+                wake_up_locked(&m->q);
+        else if (unlikely(v == -1))     /* finished dying */
+                wake_up_all_locked(&m->q);
+        spin_unlock(&m->q.lock);
+}
+
+static int wait_for_free(struct slot_map *m)
+{
+        long left = slot_timeout_secs * HZ;
+        DEFINE_WAIT(wait);
+
+        do {
+                long n = left, t;
+                if (likely(list_empty(&wait.task_list)))
+                        __add_wait_queue_tail_exclusive(&m->q, &wait);
+                set_current_state(TASK_INTERRUPTIBLE);
+
+                if (m->c > 0)
+                        break;
+
+                if (m->c < 0) {
+                        /* we are waiting for map to be installed */
+                        /* it would better be there soon, or we go away */
+                        if (n > ORANGEFS_BUFMAP_WAIT_TIMEOUT_SECS * HZ)
+                                n = ORANGEFS_BUFMAP_WAIT_TIMEOUT_SECS * HZ;
+                }
+                spin_unlock(&m->q.lock);
+                t = schedule_timeout(n);
+                spin_lock(&m->q.lock);
+                if (unlikely(!t) && n != left && m->c < 0)
+                        left = t;
+                else
+                        left = t + (left - n);
+                if (unlikely(signal_pending(current)))
+                        left = -EINTR;
+        } while (left > 0);
+
+        if (!list_empty(&wait.task_list))
+                list_del(&wait.task_list);
+        else if (left <= 0 && waitqueue_active(&m->q))
+                __wake_up_locked_key(&m->q, TASK_INTERRUPTIBLE, NULL);
+        __set_current_state(TASK_RUNNING);
+
+        if (likely(left > 0))
+                return 0;
+
+        return left < 0 ? -EINTR : -ETIMEDOUT;
+}
+
+static int get(struct slot_map *m)
+{
+        int res = 0;
+        spin_lock(&m->q.lock);
+        if (unlikely(m->c <= 0))
+                res = wait_for_free(m);
+        if (likely(!res)) {
+                m->c--;
+                res = find_first_zero_bit(m->map, m->count);
+                __set_bit(res, m->map);
+        }
+        spin_unlock(&m->q.lock);
+        return res;
+}
 
 /* used to describe mapped buffers */
 struct orangefs_bufmap_desc {
@@ -18,8 +144,6 @@ struct orangefs_bufmap_desc {
 };
 
 static struct orangefs_bufmap {
-        atomic_t refcnt;
-
         int desc_size;
         int desc_shift;
         int desc_count;
@@ -30,12 +154,12 @@ static struct orangefs_bufmap {
         struct orangefs_bufmap_desc *desc_array;
 
         /* array to track usage of buffer descriptors */
-        int *buffer_index_array;
-        spinlock_t buffer_index_lock;
+        unsigned long *buffer_index_array;
 
         /* array to track usage of buffer descriptors for readdir */
-        int readdir_index_array[ORANGEFS_READDIR_DEFAULT_DESC_COUNT];
-        spinlock_t readdir_index_lock;
+#define N DIV_ROUND_UP(ORANGEFS_READDIR_DEFAULT_DESC_COUNT, BITS_PER_LONG)
+        unsigned long readdir_index_array[N];
+#undef N
 } *__orangefs_bufmap;
 
 static DEFINE_SPINLOCK(orangefs_bufmap_lock);
@@ -58,30 +182,6 @@ orangefs_bufmap_free(struct orangefs_bufmap *bufmap)
         kfree(bufmap);
 }
 
-static struct orangefs_bufmap *orangefs_bufmap_ref(void)
-{
-        struct orangefs_bufmap *bufmap = NULL;
-
-        spin_lock(&orangefs_bufmap_lock);
-        if (__orangefs_bufmap) {
-                bufmap = __orangefs_bufmap;
-                atomic_inc(&bufmap->refcnt);
-        }
-        spin_unlock(&orangefs_bufmap_lock);
-        return bufmap;
-}
-
-static void orangefs_bufmap_unref(struct orangefs_bufmap *bufmap)
-{
-        if (atomic_dec_and_lock(&bufmap->refcnt, &orangefs_bufmap_lock)) {
-                __orangefs_bufmap = NULL;
-                spin_unlock(&orangefs_bufmap_lock);
-
-                orangefs_bufmap_unmap(bufmap);
-                orangefs_bufmap_free(bufmap);
-        }
-}
-
 /*
  * XXX: Can the size and shift change while the caller gives up the 
  * XXX: lock between calling this and doing something useful?
@@ -137,21 +237,18 @@ orangefs_bufmap_alloc(struct ORANGEFS_dev_map_desc *user_desc)
         if (!bufmap)
                 goto out;
 
-        atomic_set(&bufmap->refcnt, 1);
         bufmap->total_size = user_desc->total_size;
         bufmap->desc_count = user_desc->count;
         bufmap->desc_size = user_desc->size;
         bufmap->desc_shift = ilog2(bufmap->desc_size);
 
-        spin_lock_init(&bufmap->buffer_index_lock);
         bufmap->buffer_index_array =
-                kcalloc(bufmap->desc_count, sizeof(int), GFP_KERNEL);
+                kzalloc(DIV_ROUND_UP(bufmap->desc_count, BITS_PER_LONG), GFP_KERNEL);
         if (!bufmap->buffer_index_array) {
                 gossip_err("orangefs: could not allocate %d buffer indices\n",
                                 bufmap->desc_count);
                 goto out_free_bufmap;
         }
-        spin_lock_init(&bufmap->readdir_index_lock);
 
         bufmap->desc_array =
                 kcalloc(bufmap->desc_count, sizeof(struct orangefs_bufmap_desc),
@@ -294,24 +391,18 @@ int orangefs_bufmap_initialize(struct ORANGEFS_dev_map_desc *user_desc)
         if (__orangefs_bufmap) {
                 spin_unlock(&orangefs_bufmap_lock);
                 gossip_err("orangefs: error: bufmap already initialized.\n");
-                ret = -EALREADY;
+                ret = -EINVAL;
                 goto out_unmap_bufmap;
         }
         __orangefs_bufmap = bufmap;
+        install(&rw_map,
+                bufmap->desc_count,
+                bufmap->buffer_index_array);
+        install(&readdir_map,
+                ORANGEFS_READDIR_DEFAULT_DESC_COUNT,
+                bufmap->readdir_index_array);
         spin_unlock(&orangefs_bufmap_lock);
 
-        /*
-         * If there are operations in orangefs_bufmap_init_waitq, wake them up.
-         * This scenario occurs when the client-core is restarted and I/O
-         * requests in the in-progress or waiting tables are restarted.  I/O
-         * requests cannot be restarted until the shared memory system is
-         * completely re-initialized, so we put the I/O requests in this
-         * waitq until initialization has completed.  NOTE:  the I/O requests
-         * are also on a timer, so they don't wait forever just in case the
-         * client-core doesn't come back up.
-         */
-        wake_up_interruptible(&orangefs_bufmap_init_waitq);
-
         gossip_debug(GOSSIP_BUFMAP_DEBUG,
                      "orangefs_bufmap_initialize: exiting normally\n");
         return 0;
@@ -334,91 +425,28 @@ out:
  */
 void orangefs_bufmap_finalize(void)
 {
+        struct orangefs_bufmap *bufmap = __orangefs_bufmap;
+        if (!bufmap)
+                return;
         gossip_debug(GOSSIP_BUFMAP_DEBUG, "orangefs_bufmap_finalize: called\n");
-        BUG_ON(!__orangefs_bufmap);
-        orangefs_bufmap_unref(__orangefs_bufmap);
+        mark_killed(&rw_map);
+        mark_killed(&readdir_map);
         gossip_debug(GOSSIP_BUFMAP_DEBUG,
                      "orangefs_bufmap_finalize: exiting normally\n");
 }
 
-struct slot_args {
-        int slot_count;
-        int *slot_array;
-        spinlock_t *slot_lock;
-        wait_queue_head_t *slot_wq;
-};
-
-static int wait_for_a_slot(struct slot_args *slargs, int *buffer_index)
+void orangefs_bufmap_run_down(void)
 {
-        int ret = -1;
-        int i = 0;
-        DEFINE_WAIT(wait_entry);
-
-        while (1) {
-                /*
-                 * check for available desc, slot_lock is the appropriate
-                 * index_lock
-                 */
-                spin_lock(slargs->slot_lock);
-                prepare_to_wait_exclusive(slargs->slot_wq,
-                                          &wait_entry,
-                                          TASK_INTERRUPTIBLE);
-                for (i = 0; i < slargs->slot_count; i++)
-                        if (slargs->slot_array[i] == 0) {
-                                slargs->slot_array[i] = 1;
-                                *buffer_index = i;
-                                ret = 0;
-                                break;
-                        }
-                spin_unlock(slargs->slot_lock);
-
-                /* if we acquired a buffer, then break out of while */
-                if (ret == 0)
-                        break;
-
-                if (!signal_pending(current)) {
-                        gossip_debug(GOSSIP_BUFMAP_DEBUG,
-                                     "[BUFMAP]: waiting %d "
-                                     "seconds for a slot\n",
-                                     slot_timeout_secs);
-                        if (!schedule_timeout(slot_timeout_secs * HZ)) {
-                                gossip_debug(GOSSIP_BUFMAP_DEBUG,
-                                             "*** wait_for_a_slot timed out\n");
-                                ret = -ETIMEDOUT;
-                                break;
-                        }
-                        gossip_debug(GOSSIP_BUFMAP_DEBUG,
-                          "[BUFMAP]: woken up by a slot becoming available.\n");
-                        continue;
-                }
-
-                gossip_debug(GOSSIP_BUFMAP_DEBUG, "orangefs: %s interrupted.\n",
-                             __func__);
-                ret = -EINTR;
-                break;
-        }
-
-        spin_lock(slargs->slot_lock);
-        finish_wait(slargs->slot_wq, &wait_entry);
-        spin_unlock(slargs->slot_lock);
-        return ret;
-}
-
-static void put_back_slot(struct slot_args *slargs, int buffer_index)
-{
-        /* slot_lock is the appropriate index_lock */
-        spin_lock(slargs->slot_lock);
-        if (buffer_index < 0 || buffer_index >= slargs->slot_count) {
-                spin_unlock(slargs->slot_lock);
+        struct orangefs_bufmap *bufmap = __orangefs_bufmap;
+        if (!bufmap)
                 return;
-        }
-
-        /* put the desc back on the queue */
-        slargs->slot_array[buffer_index] = 0;
-        spin_unlock(slargs->slot_lock);
-
-        /* wake up anyone who may be sleeping on the queue */
-        wake_up_interruptible(slargs->slot_wq);
+        run_down(&rw_map);
+        run_down(&readdir_map);
+        spin_lock(&orangefs_bufmap_lock);
+        __orangefs_bufmap = NULL;
+        spin_unlock(&orangefs_bufmap_lock);
+        orangefs_bufmap_unmap(bufmap);
+        orangefs_bufmap_free(bufmap);
 }
 
 /*
@@ -431,23 +459,12 @@ static void put_back_slot(struct slot_args *slargs, int buffer_index)
  */
 int orangefs_bufmap_get(struct orangefs_bufmap **mapp, int *buffer_index)
 {
-        struct orangefs_bufmap *bufmap = orangefs_bufmap_ref();
-        struct slot_args slargs;
-        int ret;
-
-        if (!bufmap) {
-                gossip_err("orangefs: please confirm that pvfs2-client daemon is running.\n");
-                return -EIO;
+        int ret = get(&rw_map);
+        if (ret >= 0) {
+                *mapp = __orangefs_bufmap;
+                *buffer_index = ret;
+                ret = 0;
         }
-
-        slargs.slot_count = bufmap->desc_count;
-        slargs.slot_array = bufmap->buffer_index_array;
-        slargs.slot_lock = &bufmap->buffer_index_lock;
-        slargs.slot_wq = &bufmap_waitq;
-        ret = wait_for_a_slot(&slargs, buffer_index);
-        if (ret)
-                orangefs_bufmap_unref(bufmap);
-        *mapp = bufmap;
         return ret;
 }
 
@@ -460,15 +477,7 @@ int orangefs_bufmap_get(struct orangefs_bufmap **mapp, int *buffer_index)
  */
 void orangefs_bufmap_put(int buffer_index)
 {
-        struct slot_args slargs;
-        struct orangefs_bufmap *bufmap = __orangefs_bufmap;
-
-        slargs.slot_count = bufmap->desc_count;
-        slargs.slot_array = bufmap->buffer_index_array;
-        slargs.slot_lock = &bufmap->buffer_index_lock;
-        slargs.slot_wq = &bufmap_waitq;
-        put_back_slot(&slargs, buffer_index);
-        orangefs_bufmap_unref(bufmap);
+        put(&rw_map, buffer_index);
 }
 
 /*
@@ -484,36 +493,18 @@ void orangefs_bufmap_put(int buffer_index)
  */
 int orangefs_readdir_index_get(struct orangefs_bufmap **mapp, int *buffer_index)
 {
-        struct orangefs_bufmap *bufmap = orangefs_bufmap_ref();
-        struct slot_args slargs;
-        int ret;
-
-        if (!bufmap) {
-                gossip_err("orangefs: please confirm that pvfs2-client daemon is running.\n");
-                return -EIO;
+        int ret = get(&readdir_map);
+        if (ret >= 0) {
+                *mapp = __orangefs_bufmap;
+                *buffer_index = ret;
+                ret = 0;
         }
-
-        slargs.slot_count = ORANGEFS_READDIR_DEFAULT_DESC_COUNT;
-        slargs.slot_array = bufmap->readdir_index_array;
-        slargs.slot_lock = &bufmap->readdir_index_lock;
-        slargs.slot_wq = &readdir_waitq;
-        ret = wait_for_a_slot(&slargs, buffer_index);
-        if (ret)
-                orangefs_bufmap_unref(bufmap);
-        *mapp = bufmap;
         return ret;
 }
 
 void orangefs_readdir_index_put(struct orangefs_bufmap *bufmap, int buffer_index)
 {
-        struct slot_args slargs;
-
-        slargs.slot_count = ORANGEFS_READDIR_DEFAULT_DESC_COUNT;
-        slargs.slot_array = bufmap->readdir_index_array;
-        slargs.slot_lock = &bufmap->readdir_index_lock;
-        slargs.slot_wq = &readdir_waitq;
-        put_back_slot(&slargs, buffer_index);
-        orangefs_bufmap_unref(bufmap);
+        put(&readdir_map, buffer_index);
 }
 
 /*
diff --git a/fs/orangefs/orangefs-bufmap.h b/fs/orangefs/orangefs-bufmap.h
index 2a2d4269d03e..f0684f0085d1 100644
--- a/fs/orangefs/orangefs-bufmap.h
+++ b/fs/orangefs/orangefs-bufmap.h
@@ -15,10 +15,10 @@ int orangefs_bufmap_shift_query(void);
 
 int orangefs_bufmap_initialize(struct ORANGEFS_dev_map_desc *user_desc);
 
-int orangefs_get_bufmap_init(void);
-
 void orangefs_bufmap_finalize(void);
 
+void orangefs_bufmap_run_down(void);
+
 int orangefs_bufmap_get(struct orangefs_bufmap **mapp, int *buffer_index);
 
 void orangefs_bufmap_put(int buffer_index);
diff --git a/fs/orangefs/waitqueue.c b/fs/orangefs/waitqueue.c
index 378cdcf43252..36eedd6a8335 100644
--- a/fs/orangefs/waitqueue.c
+++ b/fs/orangefs/waitqueue.c
@@ -155,67 +155,6 @@ retry_servicing:
                          * system
                          */
                         goto retry_servicing;
-
-                /* op uses shared memory */
-                if (orangefs_get_bufmap_init() == 0) {
-                        WARN_ON(1);
-                        /*
-                         * This operation uses the shared memory system AND
-                         * the system is not yet ready. This situation occurs
-                         * when the client-core is restarted AND there were
-                         * operations waiting to be processed or were already
-                         * in process.
-                         */
-                        gossip_debug(GOSSIP_WAIT_DEBUG,
-                                     "uses_shared_memory is true.\n");
-                        gossip_debug(GOSSIP_WAIT_DEBUG,
-                                     "Client core in-service status(%d).\n",
-                                     is_daemon_in_service());
-                        gossip_debug(GOSSIP_WAIT_DEBUG, "bufmap_init:%d.\n",
-                                     orangefs_get_bufmap_init());
-                        gossip_debug(GOSSIP_WAIT_DEBUG,
-                                     "operation's status is 0x%0x.\n",
-                                     op->op_state);
-
-                        /*
-                         * let process sleep for a few seconds so shared
-                         * memory system can be initialized.
-                         */
-                        prepare_to_wait(&orangefs_bufmap_init_waitq,
-                                        &wait_entry,
-                                        TASK_INTERRUPTIBLE);
-
-                        /*
-                         * Wait for orangefs_bufmap_initialize() to wake me up
-                         * within the allotted time.
-                         */
-                        ret = schedule_timeout(
-                                ORANGEFS_BUFMAP_WAIT_TIMEOUT_SECS * HZ);
-
-                        gossip_debug(GOSSIP_WAIT_DEBUG,
-                                     "Value returned from schedule_timeout:"
-                                     "%d.\n",
-                                     ret);
-                        gossip_debug(GOSSIP_WAIT_DEBUG,
-                                     "Is shared memory available? (%d).\n",
-                                     orangefs_get_bufmap_init());
-
-                        finish_wait(&orangefs_bufmap_init_waitq, &wait_entry);
-
-                        if (orangefs_get_bufmap_init() == 0) {
-                                gossip_err("%s:The shared memory system has not started in %d seconds after the client core restarted.  Aborting user's request(%s).\n",
-                                           __func__,
-                                           ORANGEFS_BUFMAP_WAIT_TIMEOUT_SECS,
-                                           get_opname_string(op));
-                                return -EIO;
-                        }
-
-                        /*
-                         * Return to the calling function and re-populate a
-                         * shared memory buffer.
-                         */
-                        return -EAGAIN;
-                }
         }
 
 out: