fs/orangefs/pvfs2-bufmap.c - kernel/msm-4.9 - Gitiles

 /*
  * (C) 2001 Clemson University and The University of Chicago
  *
  * See COPYING in top-level directory.
  */
 #include "protocol.h"
 #include "pvfs2-kernel.h"
 #include "pvfs2-bufmap.h"

 DECLARE_WAIT_QUEUE_HEAD(orangefs_bufmap_init_waitq);

 static struct orangefs_bufmap {
 	atomic_t refcnt;

 	int desc_size;
 	int desc_shift;
 	int desc_count;
 	int total_size;
 	int page_count;

 	struct page **page_array;
 	struct orangefs_bufmap_desc *desc_array;

 	/* array to track usage of buffer descriptors */
 	int *buffer_index_array;
 	spinlock_t buffer_index_lock;

 	/* array to track usage of buffer descriptors for readdir */
 	int readdir_index_array[ORANGEFS_READDIR_DEFAULT_DESC_COUNT];
 	spinlock_t readdir_index_lock;
 } *__orangefs_bufmap;

 static DEFINE_SPINLOCK(orangefs_bufmap_lock);

 static void
 orangefs_bufmap_unmap(struct orangefs_bufmap *bufmap)
 {
 	int i;

 	for (i = 0; i < bufmap->page_count; i++)
 		page_cache_release(bufmap->page_array[i]);
 }

 static void
 orangefs_bufmap_free(struct orangefs_bufmap *bufmap)
 {
 	kfree(bufmap->page_array);
 	kfree(bufmap->desc_array);
 	kfree(bufmap->buffer_index_array);
 	kfree(bufmap);
 }

 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;
 }

 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);
 	}
 }

 inline int orangefs_bufmap_size_query(void)
 {
 	struct orangefs_bufmap *bufmap = orangefs_bufmap_ref();
 	int size = bufmap ? bufmap->desc_size : 0;

 	orangefs_bufmap_unref(bufmap);
 	return size;
 }

 inline int orangefs_bufmap_shift_query(void)
 {
 	struct orangefs_bufmap *bufmap = orangefs_bufmap_ref();
 	int shift = bufmap ? bufmap->desc_shift : 0;

 	orangefs_bufmap_unref(bufmap);
 	return shift;
 }

 static DECLARE_WAIT_QUEUE_HEAD(bufmap_waitq);
 static DECLARE_WAIT_QUEUE_HEAD(readdir_waitq);

 /*
  * get_bufmap_init
  *
  * If bufmap_init is 1, then the shared memory system, including the
  * buffer_index_array, is available.  Otherwise, it is not.
  *
  * returns the value of bufmap_init
  */
 int get_bufmap_init(void)
 {
 	return __orangefs_bufmap ? 1 : 0;
 }


 static struct orangefs_bufmap *
 orangefs_bufmap_alloc(struct ORANGEFS_dev_map_desc *user_desc)
 {
 	struct orangefs_bufmap *bufmap;

 	bufmap = kzalloc(sizeof(*bufmap), GFP_KERNEL);
 	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);
 	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),
 			GFP_KERNEL);
 	if (!bufmap->desc_array) {
 		gossip_err("orangefs: could not allocate %d descriptors\n",
 				bufmap->desc_count);
 		goto out_free_index_array;
 	}

 	bufmap->page_count = bufmap->total_size / PAGE_SIZE;

 	/* allocate storage to track our page mappings */
 	bufmap->page_array =
 		kcalloc(bufmap->page_count, sizeof(struct page *), GFP_KERNEL);
 	if (!bufmap->page_array)
 		goto out_free_desc_array;

 	return bufmap;

 out_free_desc_array:
 	kfree(bufmap->desc_array);
 out_free_index_array:
 	kfree(bufmap->buffer_index_array);
 out_free_bufmap:
 	kfree(bufmap);
 out:
 	return NULL;
 }

 static int
 orangefs_bufmap_map(struct orangefs_bufmap *bufmap,
 		struct ORANGEFS_dev_map_desc *user_desc)
 {
 	int pages_per_desc = bufmap->desc_size / PAGE_SIZE;
 	int offset = 0, ret, i;

 	/* map the pages */
 	ret = get_user_pages_fast((unsigned long)user_desc->ptr,
 			     bufmap->page_count, 1, bufmap->page_array);

 	if (ret < 0)
 		return ret;

 	if (ret != bufmap->page_count) {
 		gossip_err("orangefs error: asked for %d pages, only got %d.\n",
 				bufmap->page_count, ret);

 		for (i = 0; i < ret; i++) {
 			SetPageError(bufmap->page_array[i]);
 			page_cache_release(bufmap->page_array[i]);
 		}
 		return -ENOMEM;
 	}

 	/*
 	 * ideally we want to get kernel space pointers for each page, but
 	 * we can't kmap that many pages at once if highmem is being used.
 	 * so instead, we just kmap/kunmap the page address each time the
 	 * kaddr is needed.
 	 */
 	for (i = 0; i < bufmap->page_count; i++)
 		flush_dcache_page(bufmap->page_array[i]);

 	/* build a list of available descriptors */
 	for (offset = 0, i = 0; i < bufmap->desc_count; i++) {
 		bufmap->desc_array[i].page_array = &bufmap->page_array[offset];
 		bufmap->desc_array[i].array_count = pages_per_desc;
 		bufmap->desc_array[i].uaddr =
 		    (user_desc->ptr + (i * pages_per_desc * PAGE_SIZE));
 		offset += pages_per_desc;
 	}

 	return 0;
 }

 /*
  * orangefs_bufmap_initialize()
  *
  * initializes the mapped buffer interface
  *
  * returns 0 on success, -errno on failure
  */
 int orangefs_bufmap_initialize(struct ORANGEFS_dev_map_desc *user_desc)
 {
 	struct orangefs_bufmap *bufmap;
 	int ret = -EINVAL;

 	gossip_debug(GOSSIP_BUFMAP_DEBUG,
 		     "orangefs_bufmap_initialize: called (ptr ("
 		     "%p) sz (%d) cnt(%d).\n",
 		     user_desc->ptr,
 		     user_desc->size,
 		     user_desc->count);

 	/*
 	 * sanity check alignment and size of buffer that caller wants to
 	 * work with
 	 */
 	if (PAGE_ALIGN((unsigned long)user_desc->ptr) !=
 	    (unsigned long)user_desc->ptr) {
 		gossip_err("orangefs error: memory alignment (front). %p\n",
 			   user_desc->ptr);
 		goto out;
 	}

 	if (PAGE_ALIGN(((unsigned long)user_desc->ptr + user_desc->total_size))
 	    != (unsigned long)(user_desc->ptr + user_desc->total_size)) {
 		gossip_err("orangefs error: memory alignment (back).(%p + %d)\n",
 			   user_desc->ptr,
 			   user_desc->total_size);
 		goto out;
 	}

 	if (user_desc->total_size != (user_desc->size * user_desc->count)) {
 		gossip_err("orangefs error: user provided an oddly sized buffer: (%d, %d, %d)\n",
 			   user_desc->total_size,
 			   user_desc->size,
 			   user_desc->count);
 		goto out;
 	}

 	if ((user_desc->size % PAGE_SIZE) != 0) {
 		gossip_err("orangefs error: bufmap size not page size divisible (%d).\n",
 			   user_desc->size);
 		goto out;
 	}

 	ret = -ENOMEM;
 	bufmap = orangefs_bufmap_alloc(user_desc);
 	if (!bufmap)
 		goto out;

 	ret = orangefs_bufmap_map(bufmap, user_desc);
 	if (ret)
 		goto out_free_bufmap;


 	spin_lock(&orangefs_bufmap_lock);
 	if (__orangefs_bufmap) {
 		spin_unlock(&orangefs_bufmap_lock);
 		gossip_err("orangefs: error: bufmap already initialized.\n");
 		ret = -EALREADY;
 		goto out_unmap_bufmap;
 	}
 	__orangefs_bufmap = bufmap;
 	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;

 out_unmap_bufmap:
 	orangefs_bufmap_unmap(bufmap);
 out_free_bufmap:
 	orangefs_bufmap_free(bufmap);
 out:
 	return ret;
 }

 /*
  * orangefs_bufmap_finalize()
  *
  * shuts down the mapped buffer interface and releases any resources
  * associated with it
  *
  * no return value
  */
 void orangefs_bufmap_finalize(void)
 {
 	gossip_debug(GOSSIP_BUFMAP_DEBUG, "orangefs_bufmap_finalize: called\n");
 	BUG_ON(!__orangefs_bufmap);
 	orangefs_bufmap_unref(__orangefs_bufmap);
 	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)
 {
 	int ret = -1;
 	int i = 0;
 	DECLARE_WAITQUEUE(my_wait, current);


 	add_wait_queue_exclusive(slargs->slot_wq, &my_wait);

 	while (1) {
 		set_current_state(TASK_INTERRUPTIBLE);

 		/*
 		 * check for available desc, slot_lock is the appropriate
 		 * index_lock
 		 */
 		spin_lock(slargs->slot_lock);
 		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)) {
 			int timeout =
 			    MSECS_TO_JIFFIES(1000 * slot_timeout_secs);
 			gossip_debug(GOSSIP_BUFMAP_DEBUG,
 				     "[BUFMAP]: waiting %d "
 				     "seconds for a slot\n",
 				     slot_timeout_secs);
 			if (!schedule_timeout(timeout)) {
 				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;
 	}

 	set_current_state(TASK_RUNNING);
 	remove_wait_queue(slargs->slot_wq, &my_wait);
 	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);
 		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);
 }

 /*
  * orangefs_bufmap_get()
  *
  * gets a free mapped buffer descriptor, will sleep until one becomes
  * available if necessary
  *
  * returns 0 on success, -errno on failure
  */
 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;
 	}

 	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;
 }

 /*
  * orangefs_bufmap_put()
  *
  * returns a mapped buffer descriptor to the collection
  *
  * no return value
  */
 void orangefs_bufmap_put(struct orangefs_bufmap *bufmap, int buffer_index)
 {
 	struct slot_args slargs;

 	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);
 }

 /*
  * readdir_index_get()
  *
  * gets a free descriptor, will sleep until one becomes
  * available if necessary.
  * Although the readdir buffers are not mapped into kernel space
  * we could do that at a later point of time. Regardless, these
  * indices are used by the client-core.
  *
  * returns 0 on success, -errno on failure
  */
 int 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;
 	}

 	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 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);
 }

 int orangefs_bufmap_copy_from_iovec(struct orangefs_bufmap *bufmap,
 				struct iov_iter *iter,
 				int buffer_index,
 				size_t size)
 {
 	struct orangefs_bufmap_desc *to = &bufmap->desc_array[buffer_index];
 	int i;

 	gossip_debug(GOSSIP_BUFMAP_DEBUG,
 		     "%s: buffer_index:%d: size:%zu:\n",
 		     __func__, buffer_index, size);


 	for (i = 0; size; i++) {
 		struct page *page = to->page_array[i];
 		size_t n = size;
 		if (n > PAGE_SIZE)
 			n = PAGE_SIZE;
 		n = copy_page_from_iter(page, 0, n, iter);
 		if (!n)
 			return -EFAULT;
 		size -= n;
 	}
 	return 0;

 }

 /*
  * Iterate through the array of pages containing the bytes from
  * a file being read.
  *
  */
 int orangefs_bufmap_copy_to_iovec(struct orangefs_bufmap *bufmap,
 				    struct iov_iter *iter,
 				    int buffer_index,
 				    size_t size)
 {
 	struct orangefs_bufmap_desc *from = &bufmap->desc_array[buffer_index];
 	int i;

 	gossip_debug(GOSSIP_BUFMAP_DEBUG,
 		     "%s: buffer_index:%d: size:%zu:\n",
 		     __func__, buffer_index, size);


 	for (i = 0; size; i++) {
 		struct page *page = from->page_array[i];
 		size_t n = size;
 		if (n > PAGE_SIZE)
 			n = PAGE_SIZE;
 		n = copy_page_to_iter(page, 0, n, iter);
 		if (!n)
 			return -EFAULT;
 		size -= n;
 	}
 	return 0;
 }
	/*
	* (C) 2001 Clemson University and The University of Chicago
	*
	* See COPYING in top-level directory.
	*/
	#include "protocol.h"
	#include "pvfs2-kernel.h"
	#include "pvfs2-bufmap.h"

	DECLARE_WAIT_QUEUE_HEAD(orangefs_bufmap_init_waitq);

	static struct orangefs_bufmap {
	atomic_t refcnt;

	int desc_size;
	int desc_shift;
	int desc_count;
	int total_size;
	int page_count;

	struct page **page_array;
	struct orangefs_bufmap_desc *desc_array;

	/* array to track usage of buffer descriptors */
	int *buffer_index_array;
	spinlock_t buffer_index_lock;

	/* array to track usage of buffer descriptors for readdir */
	int readdir_index_array[ORANGEFS_READDIR_DEFAULT_DESC_COUNT];
	spinlock_t readdir_index_lock;
	} *__orangefs_bufmap;

	static DEFINE_SPINLOCK(orangefs_bufmap_lock);

	static void
	orangefs_bufmap_unmap(struct orangefs_bufmap *bufmap)
	{
	int i;

	for (i = 0; i < bufmap->page_count; i++)
	page_cache_release(bufmap->page_array[i]);
	}

	static void
	orangefs_bufmap_free(struct orangefs_bufmap *bufmap)
	{
	kfree(bufmap->page_array);
	kfree(bufmap->desc_array);
	kfree(bufmap->buffer_index_array);
	kfree(bufmap);
	}

	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;
	}

	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);
	}
	}

	inline int orangefs_bufmap_size_query(void)
	{
	struct orangefs_bufmap *bufmap = orangefs_bufmap_ref();
	int size = bufmap ? bufmap->desc_size : 0;

	orangefs_bufmap_unref(bufmap);
	return size;
	}

	inline int orangefs_bufmap_shift_query(void)
	{
	struct orangefs_bufmap *bufmap = orangefs_bufmap_ref();
	int shift = bufmap ? bufmap->desc_shift : 0;

	orangefs_bufmap_unref(bufmap);
	return shift;
	}

	static DECLARE_WAIT_QUEUE_HEAD(bufmap_waitq);
	static DECLARE_WAIT_QUEUE_HEAD(readdir_waitq);

	/*
	* get_bufmap_init
	*
	* If bufmap_init is 1, then the shared memory system, including the
	* buffer_index_array, is available. Otherwise, it is not.
	*
	* returns the value of bufmap_init
	*/
	int get_bufmap_init(void)
	{
	return __orangefs_bufmap ? 1 : 0;
	}


	static struct orangefs_bufmap *
	orangefs_bufmap_alloc(struct ORANGEFS_dev_map_desc *user_desc)
	{
	struct orangefs_bufmap *bufmap;

	bufmap = kzalloc(sizeof(*bufmap), GFP_KERNEL);
	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);
	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),
	GFP_KERNEL);
	if (!bufmap->desc_array) {
	gossip_err("orangefs: could not allocate %d descriptors\n",
	bufmap->desc_count);
	goto out_free_index_array;
	}

	bufmap->page_count = bufmap->total_size / PAGE_SIZE;

	/* allocate storage to track our page mappings */
	bufmap->page_array =
	kcalloc(bufmap->page_count, sizeof(struct page *), GFP_KERNEL);
	if (!bufmap->page_array)
	goto out_free_desc_array;

	return bufmap;

	out_free_desc_array:
	kfree(bufmap->desc_array);
	out_free_index_array:
	kfree(bufmap->buffer_index_array);
	out_free_bufmap:
	kfree(bufmap);
	out:
	return NULL;
	}

	static int
	orangefs_bufmap_map(struct orangefs_bufmap *bufmap,
	struct ORANGEFS_dev_map_desc *user_desc)
	{
	int pages_per_desc = bufmap->desc_size / PAGE_SIZE;
	int offset = 0, ret, i;

	/* map the pages */
	ret = get_user_pages_fast((unsigned long)user_desc->ptr,
	bufmap->page_count, 1, bufmap->page_array);

	if (ret < 0)
	return ret;

	if (ret != bufmap->page_count) {
	gossip_err("orangefs error: asked for %d pages, only got %d.\n",
	bufmap->page_count, ret);

	for (i = 0; i < ret; i++) {
	SetPageError(bufmap->page_array[i]);
	page_cache_release(bufmap->page_array[i]);
	}
	return -ENOMEM;
	}

	/*
	* ideally we want to get kernel space pointers for each page, but
	* we can't kmap that many pages at once if highmem is being used.
	* so instead, we just kmap/kunmap the page address each time the
	* kaddr is needed.
	*/
	for (i = 0; i < bufmap->page_count; i++)
	flush_dcache_page(bufmap->page_array[i]);

	/* build a list of available descriptors */
	for (offset = 0, i = 0; i < bufmap->desc_count; i++) {
	bufmap->desc_array[i].page_array = &bufmap->page_array[offset];
	bufmap->desc_array[i].array_count = pages_per_desc;
	bufmap->desc_array[i].uaddr =
	(user_desc->ptr + (i * pages_per_desc * PAGE_SIZE));
	offset += pages_per_desc;
	}

	return 0;
	}

	/*
	* orangefs_bufmap_initialize()
	*
	* initializes the mapped buffer interface
	*
	* returns 0 on success, -errno on failure
	*/
	int orangefs_bufmap_initialize(struct ORANGEFS_dev_map_desc *user_desc)
	{
	struct orangefs_bufmap *bufmap;
	int ret = -EINVAL;

	gossip_debug(GOSSIP_BUFMAP_DEBUG,
	"orangefs_bufmap_initialize: called (ptr ("
	"%p) sz (%d) cnt(%d).\n",
	user_desc->ptr,
	user_desc->size,
	user_desc->count);

	/*
	* sanity check alignment and size of buffer that caller wants to
	* work with
	*/
	if (PAGE_ALIGN((unsigned long)user_desc->ptr) !=
	(unsigned long)user_desc->ptr) {
	gossip_err("orangefs error: memory alignment (front). %p\n",
	user_desc->ptr);
	goto out;
	}

	if (PAGE_ALIGN(((unsigned long)user_desc->ptr + user_desc->total_size))
	!= (unsigned long)(user_desc->ptr + user_desc->total_size)) {
	gossip_err("orangefs error: memory alignment (back).(%p + %d)\n",
	user_desc->ptr,
	user_desc->total_size);
	goto out;
	}

	if (user_desc->total_size != (user_desc->size * user_desc->count)) {
	gossip_err("orangefs error: user provided an oddly sized buffer: (%d, %d, %d)\n",
	user_desc->total_size,
	user_desc->size,
	user_desc->count);
	goto out;
	}

	if ((user_desc->size % PAGE_SIZE) != 0) {
	gossip_err("orangefs error: bufmap size not page size divisible (%d).\n",
	user_desc->size);
	goto out;
	}

	ret = -ENOMEM;
	bufmap = orangefs_bufmap_alloc(user_desc);
	if (!bufmap)
	goto out;

	ret = orangefs_bufmap_map(bufmap, user_desc);
	if (ret)
	goto out_free_bufmap;


	spin_lock(&orangefs_bufmap_lock);
	if (__orangefs_bufmap) {
	spin_unlock(&orangefs_bufmap_lock);
	gossip_err("orangefs: error: bufmap already initialized.\n");
	ret = -EALREADY;
	goto out_unmap_bufmap;
	}
	__orangefs_bufmap = bufmap;
	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;

	out_unmap_bufmap:
	orangefs_bufmap_unmap(bufmap);
	out_free_bufmap:
	orangefs_bufmap_free(bufmap);
	out:
	return ret;
	}

	/*
	* orangefs_bufmap_finalize()
	*
	* shuts down the mapped buffer interface and releases any resources
	* associated with it
	*
	* no return value
	*/
	void orangefs_bufmap_finalize(void)
	{
	gossip_debug(GOSSIP_BUFMAP_DEBUG, "orangefs_bufmap_finalize: called\n");
	BUG_ON(!__orangefs_bufmap);
	orangefs_bufmap_unref(__orangefs_bufmap);
	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)
	{
	int ret = -1;
	int i = 0;
	DECLARE_WAITQUEUE(my_wait, current);


	add_wait_queue_exclusive(slargs->slot_wq, &my_wait);

	while (1) {
	set_current_state(TASK_INTERRUPTIBLE);

	/*
	* check for available desc, slot_lock is the appropriate
	* index_lock
	*/
	spin_lock(slargs->slot_lock);
	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)) {
	int timeout =
	MSECS_TO_JIFFIES(1000 * slot_timeout_secs);
	gossip_debug(GOSSIP_BUFMAP_DEBUG,
	"[BUFMAP]: waiting %d "
	"seconds for a slot\n",
	slot_timeout_secs);
	if (!schedule_timeout(timeout)) {
	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;
	}

	set_current_state(TASK_RUNNING);
	remove_wait_queue(slargs->slot_wq, &my_wait);
	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);
	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);
	}

	/*
	* orangefs_bufmap_get()
	*
	* gets a free mapped buffer descriptor, will sleep until one becomes
	* available if necessary
	*
	* returns 0 on success, -errno on failure
	*/
	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;
	}

	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;
	}

	/*
	* orangefs_bufmap_put()
	*
	* returns a mapped buffer descriptor to the collection
	*
	* no return value
	*/
	void orangefs_bufmap_put(struct orangefs_bufmap *bufmap, int buffer_index)
	{
	struct slot_args slargs;

	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);
	}

	/*
	* readdir_index_get()
	*
	* gets a free descriptor, will sleep until one becomes
	* available if necessary.
	* Although the readdir buffers are not mapped into kernel space
	* we could do that at a later point of time. Regardless, these
	* indices are used by the client-core.
	*
	* returns 0 on success, -errno on failure
	*/
	int 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;
	}

	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 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);
	}

	int orangefs_bufmap_copy_from_iovec(struct orangefs_bufmap *bufmap,
	struct iov_iter *iter,
	int buffer_index,
	size_t size)
	{
	struct orangefs_bufmap_desc *to = &bufmap->desc_array[buffer_index];
	int i;

	gossip_debug(GOSSIP_BUFMAP_DEBUG,
	"%s: buffer_index:%d: size:%zu:\n",
	__func__, buffer_index, size);


	for (i = 0; size; i++) {
	struct page *page = to->page_array[i];
	size_t n = size;
	if (n > PAGE_SIZE)
	n = PAGE_SIZE;
	n = copy_page_from_iter(page, 0, n, iter);
	if (!n)
	return -EFAULT;
	size -= n;
	}
	return 0;

	}

	/*
	* Iterate through the array of pages containing the bytes from
	* a file being read.
	*
	*/
	int orangefs_bufmap_copy_to_iovec(struct orangefs_bufmap *bufmap,
	struct iov_iter *iter,
	int buffer_index,
	size_t size)
	{
	struct orangefs_bufmap_desc *from = &bufmap->desc_array[buffer_index];
	int i;

	gossip_debug(GOSSIP_BUFMAP_DEBUG,
	"%s: buffer_index:%d: size:%zu:\n",
	__func__, buffer_index, size);


	for (i = 0; size; i++) {
	struct page *page = from->page_array[i];
	size_t n = size;
	if (n > PAGE_SIZE)
	n = PAGE_SIZE;
	n = copy_page_to_iter(page, 0, n, iter);
	if (!n)
	return -EFAULT;
	size -= n;
	}
	return 0;
	}