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rtems/cpukit/libblock/src/bdbuf.c
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Chris Johns 945884fe9f 2009-08-06 Chris Johns <chrisj@rtems.org> 
* libblock/src/bdbuf.c: Fix group user logic.
        * libblock/include/rtems/blkdev.h, libblock/src/blkdev.c,
        libblock/src/nvdisk.c, libblock/src/flashdisk.c: Add set block
        size, and get media block size support.
2009-08-06 03:58:09 +00:00

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/**
* @file
*
* @ingroup rtems_bdbuf
*
* Block device buffer management.
*/
/*
* Disk I/O buffering
* Buffer managment
*
* Copyright (C) 2001 OKTET Ltd., St.-Peterburg, Russia
* Author: Andrey G. Ivanov <Andrey.Ivanov@oktet.ru>
* Victor V. Vengerov <vvv@oktet.ru>
* Alexander Kukuta <kam@oktet.ru>
*
* Copyright (C) 2008,2009 Chris Johns <chrisj@rtems.org>
* Rewritten to remove score mutex access. Fixes many performance
* issues.
*
* @(#) bdbuf.c,v 1.14 2004/04/17 08:15:17 ralf Exp
*/
/**
* Set to 1 to enable debug tracing.
*/
#define RTEMS_BDBUF_TRACE 0
#if HAVE_CONFIG_H
#include "config.h"
#endif
#include <rtems.h>
#include <rtems/error.h>
#include <rtems/malloc.h>
#include <limits.h>
#include <errno.h>
#include <assert.h>
#if RTEMS_BDBUF_TRACE
#include <stdio.h>
#endif
#include "rtems/bdbuf.h"
/*
* Simpler label for this file.
*/
#define bdbuf_config rtems_bdbuf_configuration
/**
* A swapout transfer transaction data. This data is passed to a worked thread
* to handle the write phase of the transfer.
*/
typedef struct rtems_bdbuf_swapout_transfer
{
rtems_chain_control bds; /**< The transfer list of BDs. */
dev_t dev; /**< The device the transfer is for. */
rtems_blkdev_request* write_req; /**< The write request array. */
} rtems_bdbuf_swapout_transfer;
/**
* Swapout worker thread. These are available to take processing from the
* main swapout thread and handle the I/O operation.
*/
typedef struct rtems_bdbuf_swapout_worker
{
rtems_chain_node link; /**< The threads sit on a chain when
* idle. */
rtems_id id; /**< The id of the task so we can wake
* it. */
volatile bool enabled; /**< The worked is enabled. */
rtems_bdbuf_swapout_transfer transfer; /**< The transfer data for this
* thread. */
} rtems_bdbuf_swapout_worker;
/**
* The BD buffer cache.
*/
typedef struct rtems_bdbuf_cache
{
rtems_id swapout; /**< Swapout task ID */
volatile bool swapout_enabled; /**< Swapout is only running if
* enabled. Set to false to kill the
* swap out task. It deletes itself. */
rtems_chain_control swapout_workers; /**< The work threads for the swapout
* task. */
rtems_bdbuf_buffer* bds; /**< Pointer to table of buffer
* descriptors. */
void* buffers; /**< The buffer's memory. */
size_t buffer_min_count; /**< Number of minimum size buffers
* that fit the buffer memory. */
size_t max_bds_per_group; /**< The number of BDs of minimum
* buffer size that fit in a group. */
uint32_t flags; /**< Configuration flags. */
rtems_id lock; /**< The cache lock. It locks all
* cache data, BD and lists. */
rtems_id sync_lock; /**< Sync calls block writes. */
volatile bool sync_active; /**< True if a sync is active. */
volatile rtems_id sync_requester; /**< The sync requester. */
volatile dev_t sync_device; /**< The device to sync and -1 not a
* device sync. */
rtems_bdbuf_buffer* tree; /**< Buffer descriptor lookup AVL tree
* root. There is only one. */
rtems_chain_control ready; /**< Free buffers list, read-ahead, or
* resized group buffers. */
rtems_chain_control lru; /**< Least recently used list */
rtems_chain_control modified; /**< Modified buffers list */
rtems_chain_control sync; /**< Buffers to sync list */
rtems_id access; /**< Obtain if waiting for a buffer in
* the ACCESS state. */
volatile uint32_t access_waiters; /**< Count of access blockers. */
rtems_id transfer; /**< Obtain if waiting for a buffer in
* the TRANSFER state. */
volatile uint32_t transfer_waiters; /**< Count of transfer blockers. */
rtems_id waiting; /**< Obtain if waiting for a buffer
* and the none are available. */
volatile uint32_t wait_waiters; /**< Count of waiting blockers. */
size_t group_count; /**< The number of groups. */
rtems_bdbuf_group* groups; /**< The groups. */
bool initialised; /**< Initialised state. */
} rtems_bdbuf_cache;
/**
* Fatal errors
*/
#define RTEMS_BLKDEV_FATAL_ERROR(n) \
(((uint32_t)'B' << 24) | ((uint32_t)(n) & (uint32_t)0x00FFFFFF))
#define RTEMS_BLKDEV_FATAL_BDBUF_CONSISTENCY_1 RTEMS_BLKDEV_FATAL_ERROR(1)
#define RTEMS_BLKDEV_FATAL_BDBUF_CONSISTENCY_2 RTEMS_BLKDEV_FATAL_ERROR(2)
#define RTEMS_BLKDEV_FATAL_BDBUF_CONSISTENCY_3 RTEMS_BLKDEV_FATAL_ERROR(3)
#define RTEMS_BLKDEV_FATAL_BDBUF_CONSISTENCY_4 RTEMS_BLKDEV_FATAL_ERROR(4)
#define RTEMS_BLKDEV_FATAL_BDBUF_CONSISTENCY_5 RTEMS_BLKDEV_FATAL_ERROR(5)
#define RTEMS_BLKDEV_FATAL_BDBUF_CONSISTENCY_6 RTEMS_BLKDEV_FATAL_ERROR(6)
#define RTEMS_BLKDEV_FATAL_BDBUF_CONSISTENCY_7 RTEMS_BLKDEV_FATAL_ERROR(7)
#define RTEMS_BLKDEV_FATAL_BDBUF_CONSISTENCY_8 RTEMS_BLKDEV_FATAL_ERROR(8)
#define RTEMS_BLKDEV_FATAL_BDBUF_CONSISTENCY_9 RTEMS_BLKDEV_FATAL_ERROR(9)
#define RTEMS_BLKDEV_FATAL_BDBUF_SWAPOUT RTEMS_BLKDEV_FATAL_ERROR(10)
#define RTEMS_BLKDEV_FATAL_BDBUF_SYNC_LOCK RTEMS_BLKDEV_FATAL_ERROR(11)
#define RTEMS_BLKDEV_FATAL_BDBUF_SYNC_UNLOCK RTEMS_BLKDEV_FATAL_ERROR(12)
#define RTEMS_BLKDEV_FATAL_BDBUF_CACHE_LOCK RTEMS_BLKDEV_FATAL_ERROR(13)
#define RTEMS_BLKDEV_FATAL_BDBUF_CACHE_UNLOCK RTEMS_BLKDEV_FATAL_ERROR(14)
#define RTEMS_BLKDEV_FATAL_BDBUF_CACHE_WAIT_1 RTEMS_BLKDEV_FATAL_ERROR(15)
#define RTEMS_BLKDEV_FATAL_BDBUF_CACHE_WAIT_2 RTEMS_BLKDEV_FATAL_ERROR(16)
#define RTEMS_BLKDEV_FATAL_BDBUF_CACHE_WAIT_3 RTEMS_BLKDEV_FATAL_ERROR(17)
#define RTEMS_BLKDEV_FATAL_BDBUF_CACHE_WAKE RTEMS_BLKDEV_FATAL_ERROR(18)
#define RTEMS_BLKDEV_FATAL_BDBUF_SO_WAKE RTEMS_BLKDEV_FATAL_ERROR(19)
#define RTEMS_BLKDEV_FATAL_BDBUF_SO_NOMEM RTEMS_BLKDEV_FATAL_ERROR(20)
#define RTEMS_BLKDEV_FATAL_BDBUF_SO_WK_CREATE RTEMS_BLKDEV_FATAL_ERROR(21)
#define RTEMS_BLKDEV_FATAL_BDBUF_SO_WK_START RTEMS_BLKDEV_FATAL_ERROR(22)
#define BLKDEV_FATAL_BDBUF_SWAPOUT_RE RTEMS_BLKDEV_FATAL_ERROR(23)
#define BLKDEV_FATAL_BDBUF_SWAPOUT_TS RTEMS_BLKDEV_FATAL_ERROR(24)
/**
* The events used in this code. These should be system events rather than
* application events.
*/
#define RTEMS_BDBUF_TRANSFER_SYNC RTEMS_EVENT_1
#define RTEMS_BDBUF_SWAPOUT_SYNC RTEMS_EVENT_2
/**
* The swap out task size. Should be more than enough for most drivers with
* tracing turned on.
*/
#define SWAPOUT_TASK_STACK_SIZE (8 * 1024)
/**
* Lock semaphore attributes. This is used for locking type mutexes.
*
* @warning Priority inheritance is on.
*/
#define RTEMS_BDBUF_CACHE_LOCK_ATTRIBS \
(RTEMS_PRIORITY | RTEMS_BINARY_SEMAPHORE | \
RTEMS_INHERIT_PRIORITY | RTEMS_NO_PRIORITY_CEILING | RTEMS_LOCAL)
/**
* Waiter semaphore attributes.
*
* @warning Do not configure as inherit priority. If a driver is in the driver
* initialisation table this locked semaphore will have the IDLE task
* as the holder and a blocking task will raise the priority of the
* IDLE task which can cause unsual side effects.
*/
#define RTEMS_BDBUF_CACHE_WAITER_ATTRIBS \
(RTEMS_PRIORITY | RTEMS_SIMPLE_BINARY_SEMAPHORE | \
RTEMS_NO_INHERIT_PRIORITY | RTEMS_NO_PRIORITY_CEILING | RTEMS_LOCAL)
/*
* The swap out task.
*/
static rtems_task rtems_bdbuf_swapout_task(rtems_task_argument arg);
/**
* The Buffer Descriptor cache.
*/
static rtems_bdbuf_cache bdbuf_cache;
/**
* Print a message to the bdbuf trace output and flush it.
*
* @param format The format string. See printf for details.
* @param ... The arguments for the format text.
* @return int The number of bytes written to the output.
*/
#if RTEMS_BDBUF_TRACE
bool rtems_bdbuf_tracer;
static void
rtems_bdbuf_printf (const char *format, ...)
{
va_list args;
va_start (args, format);
if (rtems_bdbuf_tracer)
{
fprintf (stdout, "bdbuf:");
vfprintf (stdout, format, args);
fflush (stdout);
}
}
#endif
/**
* The default maximum height of 32 allows for AVL trees having between
* 5,704,880 and 4,294,967,295 nodes, depending on order of insertion. You may
* change this compile-time constant as you wish.
*/
#ifndef RTEMS_BDBUF_AVL_MAX_HEIGHT
#define RTEMS_BDBUF_AVL_MAX_HEIGHT (32)
#endif
/**
* Searches for the node with specified dev/block.
*
* @param root pointer to the root node of the AVL-Tree
* @param dev device search key
* @param block block search key
* @retval NULL node with the specified dev/block is not found
* @return pointer to the node with specified dev/block
*/
static rtems_bdbuf_buffer *
rtems_bdbuf_avl_search (rtems_bdbuf_buffer** root,
dev_t dev,
rtems_blkdev_bnum block)
{
rtems_bdbuf_buffer* p = *root;
while ((p != NULL) && ((p->dev != dev) || (p->block != block)))
{
if ((p->dev < dev) || ((p->dev == dev) && (p->block < block)))
{
p = p->avl.right;
}
else
{
p = p->avl.left;
}
}
return p;
}
/**
* Inserts the specified node to the AVl-Tree.
*
* @param root pointer to the root node of the AVL-Tree
* @param node Pointer to the node to add.
* @retval 0 The node added successfully
* @retval -1 An error occured
*/
static int
rtems_bdbuf_avl_insert(rtems_bdbuf_buffer** root,
rtems_bdbuf_buffer* node)
{
dev_t dev = node->dev;
rtems_blkdev_bnum block = node->block;
rtems_bdbuf_buffer* p = *root;
rtems_bdbuf_buffer* q;
rtems_bdbuf_buffer* p1;
rtems_bdbuf_buffer* p2;
rtems_bdbuf_buffer* buf_stack[RTEMS_BDBUF_AVL_MAX_HEIGHT];
rtems_bdbuf_buffer** buf_prev = buf_stack;
bool modified = false;
if (p == NULL)
{
*root = node;
node->avl.left = NULL;
node->avl.right = NULL;
node->avl.bal = 0;
return 0;
}
while (p != NULL)
{
*buf_prev++ = p;
if ((p->dev < dev) || ((p->dev == dev) && (p->block < block)))
{
p->avl.cache = 1;
q = p->avl.right;
if (q == NULL)
{
q = node;
p->avl.right = q = node;
break;
}
}
else if ((p->dev != dev) || (p->block != block))
{
p->avl.cache = -1;
q = p->avl.left;
if (q == NULL)
{
q = node;
p->avl.left = q;
break;
}
}
else
{
return -1;
}
p = q;
}
q->avl.left = q->avl.right = NULL;
q->avl.bal = 0;
modified = true;
buf_prev--;
while (modified)
{
if (p->avl.cache == -1)
{
switch (p->avl.bal)
{
case 1:
p->avl.bal = 0;
modified = false;
break;
case 0:
p->avl.bal = -1;
break;
case -1:
p1 = p->avl.left;
if (p1->avl.bal == -1) /* simple LL-turn */
{
p->avl.left = p1->avl.right;
p1->avl.right = p;
p->avl.bal = 0;
p = p1;
}
else /* double LR-turn */
{
p2 = p1->avl.right;
p1->avl.right = p2->avl.left;
p2->avl.left = p1;
p->avl.left = p2->avl.right;
p2->avl.right = p;
if (p2->avl.bal == -1) p->avl.bal = +1; else p->avl.bal = 0;
if (p2->avl.bal == +1) p1->avl.bal = -1; else p1->avl.bal = 0;
p = p2;
}
p->avl.bal = 0;
modified = false;
break;
default:
break;
}
}
else
{
switch (p->avl.bal)
{
case -1:
p->avl.bal = 0;
modified = false;
break;
case 0:
p->avl.bal = 1;
break;
case 1:
p1 = p->avl.right;
if (p1->avl.bal == 1) /* simple RR-turn */
{
p->avl.right = p1->avl.left;
p1->avl.left = p;
p->avl.bal = 0;
p = p1;
}
else /* double RL-turn */
{
p2 = p1->avl.left;
p1->avl.left = p2->avl.right;
p2->avl.right = p1;
p->avl.right = p2->avl.left;
p2->avl.left = p;
if (p2->avl.bal == +1) p->avl.bal = -1; else p->avl.bal = 0;
if (p2->avl.bal == -1) p1->avl.bal = +1; else p1->avl.bal = 0;
p = p2;
}
p->avl.bal = 0;
modified = false;
break;
default:
break;
}
}
q = p;
if (buf_prev > buf_stack)
{
p = *--buf_prev;
if (p->avl.cache == -1)
{
p->avl.left = q;
}
else
{
p->avl.right = q;
}
}
else
{
*root = p;
break;
}
};
return 0;
}
/**
* Removes the node from the tree.
*
* @param root Pointer to pointer to the root node
* @param node Pointer to the node to remove
* @retval 0 Item removed
* @retval -1 No such item found
*/
static int
rtems_bdbuf_avl_remove(rtems_bdbuf_buffer** root,
const rtems_bdbuf_buffer* node)
{
dev_t dev = node->dev;
rtems_blkdev_bnum block = node->block;
rtems_bdbuf_buffer* p = *root;
rtems_bdbuf_buffer* q;
rtems_bdbuf_buffer* r;
rtems_bdbuf_buffer* s;
rtems_bdbuf_buffer* p1;
rtems_bdbuf_buffer* p2;
rtems_bdbuf_buffer* buf_stack[RTEMS_BDBUF_AVL_MAX_HEIGHT];
rtems_bdbuf_buffer** buf_prev = buf_stack;
bool modified = false;
memset (buf_stack, 0, sizeof(buf_stack));
while (p != NULL)
{
*buf_prev++ = p;
if ((p->dev < dev) || ((p->dev == dev) && (p->block < block)))
{
p->avl.cache = 1;
p = p->avl.right;
}
else if ((p->dev != dev) || (p->block != block))
{
p->avl.cache = -1;
p = p->avl.left;
}
else
{
/* node found */
break;
}
}
if (p == NULL)
{
/* there is no such node */
return -1;
}
q = p;
buf_prev--;
if (buf_prev > buf_stack)
{
p = *(buf_prev - 1);
}
else
{
p = NULL;
}
/* at this moment q - is a node to delete, p is q's parent */
if (q->avl.right == NULL)
{
r = q->avl.left;
if (r != NULL)
{
r->avl.bal = 0;
}
q = r;
}
else
{
rtems_bdbuf_buffer **t;
r = q->avl.right;
if (r->avl.left == NULL)
{
r->avl.left = q->avl.left;
r->avl.bal = q->avl.bal;
r->avl.cache = 1;
*buf_prev++ = q = r;
}
else
{
t = buf_prev++;
s = r;
while (s->avl.left != NULL)
{
*buf_prev++ = r = s;
s = r->avl.left;
r->avl.cache = -1;
}
s->avl.left = q->avl.left;
r->avl.left = s->avl.right;
s->avl.right = q->avl.right;
s->avl.bal = q->avl.bal;
s->avl.cache = 1;
*t = q = s;
}
}
if (p != NULL)
{
if (p->avl.cache == -1)
{
p->avl.left = q;
}
else
{
p->avl.right = q;
}
}
else
{
*root = q;
}
modified = true;
while (modified)
{
if (buf_prev > buf_stack)
{
p = *--buf_prev;
}
else
{
break;
}
if (p->avl.cache == -1)
{
/* rebalance left branch */
switch (p->avl.bal)
{
case -1:
p->avl.bal = 0;
break;
case 0:
p->avl.bal = 1;
modified = false;
break;
case +1:
p1 = p->avl.right;
if (p1->avl.bal >= 0) /* simple RR-turn */
{
p->avl.right = p1->avl.left;
p1->avl.left = p;
if (p1->avl.bal == 0)
{
p1->avl.bal = -1;
modified = false;
}
else
{
p->avl.bal = 0;
p1->avl.bal = 0;
}
p = p1;
}
else /* double RL-turn */
{
p2 = p1->avl.left;
p1->avl.left = p2->avl.right;
p2->avl.right = p1;
p->avl.right = p2->avl.left;
p2->avl.left = p;
if (p2->avl.bal == +1) p->avl.bal = -1; else p->avl.bal = 0;
if (p2->avl.bal == -1) p1->avl.bal = 1; else p1->avl.bal = 0;
p = p2;
p2->avl.bal = 0;
}
break;
default:
break;
}
}
else
{
/* rebalance right branch */
switch (p->avl.bal)
{
case +1:
p->avl.bal = 0;
break;
case 0:
p->avl.bal = -1;
modified = false;
break;
case -1:
p1 = p->avl.left;
if (p1->avl.bal <= 0) /* simple LL-turn */
{
p->avl.left = p1->avl.right;
p1->avl.right = p;
if (p1->avl.bal == 0)
{
p1->avl.bal = 1;
modified = false;
}
else
{
p->avl.bal = 0;
p1->avl.bal = 0;
}
p = p1;
}
else /* double LR-turn */
{
p2 = p1->avl.right;
p1->avl.right = p2->avl.left;
p2->avl.left = p1;
p->avl.left = p2->avl.right;
p2->avl.right = p;
if (p2->avl.bal == -1) p->avl.bal = 1; else p->avl.bal = 0;
if (p2->avl.bal == +1) p1->avl.bal = -1; else p1->avl.bal = 0;
p = p2;
p2->avl.bal = 0;
}
break;
default:
break;
}
}
if (buf_prev > buf_stack)
{
q = *(buf_prev - 1);
if (q->avl.cache == -1)
{
q->avl.left = p;
}
else
{
q->avl.right = p;
}
}
else
{
*root = p;
break;
}
}
return 0;
}
/**
* Lock the mutex. A single task can nest calls.
*
* @param lock The mutex to lock.
* @param fatal_error_code The error code if the call fails.
*/
static void
rtems_bdbuf_lock (rtems_id lock, uint32_t fatal_error_code)
{
rtems_status_code sc = rtems_semaphore_obtain (lock,
RTEMS_WAIT,
RTEMS_NO_TIMEOUT);
if (sc != RTEMS_SUCCESSFUL)
rtems_fatal_error_occurred (fatal_error_code);
}
/**
* Unlock the mutex.
*
* @param lock The mutex to unlock.
* @param fatal_error_code The error code if the call fails.
*/
static void
rtems_bdbuf_unlock (rtems_id lock, uint32_t fatal_error_code)
{
rtems_status_code sc = rtems_semaphore_release (lock);
if (sc != RTEMS_SUCCESSFUL)
rtems_fatal_error_occurred (fatal_error_code);
}
/**
* Lock the cache. A single task can nest calls.
*/
static void
rtems_bdbuf_lock_cache (void)
{
rtems_bdbuf_lock (bdbuf_cache.lock, RTEMS_BLKDEV_FATAL_BDBUF_CACHE_LOCK);
}
/**
* Unlock the cache.
*/
static void
rtems_bdbuf_unlock_cache (void)
{
rtems_bdbuf_unlock (bdbuf_cache.lock, RTEMS_BLKDEV_FATAL_BDBUF_CACHE_UNLOCK);
}
/**
* Lock the cache's sync. A single task can nest calls.
*/
static void
rtems_bdbuf_lock_sync (void)
{
rtems_bdbuf_lock (bdbuf_cache.sync_lock, RTEMS_BLKDEV_FATAL_BDBUF_SYNC_LOCK);
}
/**
* Unlock the cache's sync lock. Any blocked writers are woken.
*/
static void
rtems_bdbuf_unlock_sync (void)
{
rtems_bdbuf_unlock (bdbuf_cache.sync_lock,
RTEMS_BLKDEV_FATAL_BDBUF_SYNC_UNLOCK);
}
/**
* Wait until woken. Semaphores are used so a number of tasks can wait and can
* be woken at once. Task events would require we maintain a list of tasks to
* be woken and this would require storgage and we do not know the number of
* tasks that could be waiting.
*
* While we have the cache locked we can try and claim the semaphore and
* therefore know when we release the lock to the cache we will block until the
* semaphore is released. This may even happen before we get to block.
*
* A counter is used to save the release call when no one is waiting.
*
* The function assumes the cache is locked on entry and it will be locked on
* exit.
*
* @param sema The semaphore to block on and wait.
* @param waiters The wait counter for this semaphore.
*/
static void
rtems_bdbuf_wait (rtems_id* sema, volatile uint32_t* waiters)
{
rtems_status_code sc;
rtems_mode prev_mode;
/*
* Indicate we are waiting.
*/
*waiters += 1;
/*
* Disable preemption then unlock the cache and block. There is no POSIX
* condition variable in the core API so this is a work around.
*
* The issue is a task could preempt after the cache is unlocked because it is
* blocking or just hits that window, and before this task has blocked on the
* semaphore. If the preempting task flushes the queue this task will not see
* the flush and may block for ever or until another transaction flushes this
* semaphore.
*/
sc = rtems_task_mode (RTEMS_NO_PREEMPT, RTEMS_PREEMPT_MASK, &prev_mode);
if (sc != RTEMS_SUCCESSFUL)
rtems_fatal_error_occurred (RTEMS_BLKDEV_FATAL_BDBUF_CACHE_WAIT_1);
/*
* Unlock the cache, wait, and lock the cache when we return.
*/
rtems_bdbuf_unlock_cache ();
sc = rtems_semaphore_obtain (*sema, RTEMS_WAIT, RTEMS_NO_TIMEOUT);
if (sc != RTEMS_UNSATISFIED)
rtems_fatal_error_occurred (RTEMS_BLKDEV_FATAL_BDBUF_CACHE_WAIT_2);
rtems_bdbuf_lock_cache ();
sc = rtems_task_mode (prev_mode, RTEMS_ALL_MODE_MASKS, &prev_mode);
if (sc != RTEMS_SUCCESSFUL)
rtems_fatal_error_occurred (RTEMS_BLKDEV_FATAL_BDBUF_CACHE_WAIT_3);
*waiters -= 1;
}
/**
* Wake a blocked resource. The resource has a counter that lets us know if
* there are any waiters.
*
* @param sema The semaphore to release.
* @param waiters The wait counter for this semaphore.
*/
static void
rtems_bdbuf_wake (rtems_id sema, volatile uint32_t* waiters)
{
if (*waiters)
{
rtems_status_code sc;
sc = rtems_semaphore_flush (sema);
if (sc != RTEMS_SUCCESSFUL)
rtems_fatal_error_occurred (RTEMS_BLKDEV_FATAL_BDBUF_CACHE_WAKE);
}
}
/**
* Add a buffer descriptor to the modified list. This modified list is treated
* a litte differently to the other lists. To access it you must have the cache
* locked and this is assumed to be the case on entry to this call.
*
* If the cache has a device being sync'ed and the bd is for that device the
* call must block and wait until the sync is over before adding the bd to the
* modified list. Once a sync happens for a device no bd's can be added the
* modified list. The disk image is forced to be snapshot at that moment in
* time.
*
* @note Do not lower the group user count as the modified list is a user of
* the buffer.
*
* @param bd The bd to queue to the cache's modified list.
*/
static void
rtems_bdbuf_append_modified (rtems_bdbuf_buffer* bd)
{
/*
* If the cache has a device being sync'ed check if this bd is for that
* device. If it is unlock the cache and block on the sync lock. Once we have
* the sync lock release it.
*/
if (bdbuf_cache.sync_active && (bdbuf_cache.sync_device == bd->dev))
{
rtems_bdbuf_unlock_cache ();
/* Wait for the sync lock */
rtems_bdbuf_lock_sync ();
rtems_bdbuf_unlock_sync ();
rtems_bdbuf_lock_cache ();
}
bd->state = RTEMS_BDBUF_STATE_MODIFIED;
rtems_chain_append (&bdbuf_cache.modified, &bd->link);
}
/**
* Wait the swapper task.
*/
static void
rtems_bdbuf_wake_swapper (void)
{
rtems_status_code sc = rtems_event_send (bdbuf_cache.swapout,
RTEMS_BDBUF_SWAPOUT_SYNC);
if (sc != RTEMS_SUCCESSFUL)
rtems_fatal_error_occurred (RTEMS_BLKDEV_FATAL_BDBUF_SO_WAKE);
}
/**
* Compute the number of BDs per group for a given buffer size.
*
* @param size The buffer size. It can be any size and we scale up.
*/
static size_t
rtems_bdbuf_bds_per_group (size_t size)
{
size_t bufs_per_size;
size_t bds_per_size;
if (size > rtems_bdbuf_configuration.buffer_max)
return 0;
bufs_per_size = ((size - 1) / bdbuf_config.buffer_min) + 1;
for (bds_per_size = 1;
bds_per_size < bufs_per_size;
bds_per_size <<= 1)
;
return bdbuf_cache.max_bds_per_group / bds_per_size;
}
/**
* Reallocate a group. The BDs currently allocated in the group are removed
* from the ALV tree and any lists then the new BD's are prepended to the ready
* list of the cache.
*
* @param group The group to reallocate.
* @param new_bds_per_group The new count of BDs per group.
*/
static void
rtems_bdbuf_group_realloc (rtems_bdbuf_group* group, size_t new_bds_per_group)
{
rtems_bdbuf_buffer* bd;
int b;
size_t bufs_per_bd;
bufs_per_bd = bdbuf_cache.max_bds_per_group / group->bds_per_group;
for (b = 0, bd = group->bdbuf;
b < group->bds_per_group;
b++, bd += bufs_per_bd)
{
if ((bd->state == RTEMS_BDBUF_STATE_MODIFIED) ||
(bd->state == RTEMS_BDBUF_STATE_ACCESS) ||
(bd->state == RTEMS_BDBUF_STATE_ACCESS_MODIFIED) ||
(bd->state == RTEMS_BDBUF_STATE_SYNC) ||
(bd->state == RTEMS_BDBUF_STATE_TRANSFER))
rtems_fatal_error_occurred ((bd->state << 16) |
RTEMS_BLKDEV_FATAL_BDBUF_CONSISTENCY_8);
if ((bd->state == RTEMS_BDBUF_STATE_CACHED) ||
(bd->state == RTEMS_BDBUF_STATE_READ_AHEAD))
{
if (rtems_bdbuf_avl_remove (&bdbuf_cache.tree, bd) != 0)
rtems_fatal_error_occurred ((bd->state << 16) |
RTEMS_BLKDEV_FATAL_BDBUF_CONSISTENCY_1);
}
rtems_chain_extract (&bd->link);
}
group->bds_per_group = new_bds_per_group;
bufs_per_bd = bdbuf_cache.max_bds_per_group / new_bds_per_group;
for (b = 0, bd = group->bdbuf;
b < group->bds_per_group;
b++, bd += bufs_per_bd)
{
bd->state = RTEMS_BDBUF_STATE_EMPTY;
rtems_chain_prepend (&bdbuf_cache.ready, &bd->link);
}
}
/**
* Get the next BD from the list. This call assumes the cache is locked.
*
* @param bds_per_group The number of BDs per block we are need.
* @param list The list to find the BD on.
* @return The next BD if found or NULL is none are available.
*/
static rtems_bdbuf_buffer*
rtems_bdbuf_get_next_bd (size_t bds_per_group,
rtems_chain_control* list)
{
rtems_chain_node* node = rtems_chain_first (list);
while (!rtems_chain_is_tail (list, node))
{
rtems_bdbuf_buffer* bd = (rtems_bdbuf_buffer*) node;
/*
* If this bd is already part of a group that supports the same number of
* BDs per group return it. If the bd is part of another group check the
* number of users and if 0 we can take this group and resize it.
*/
if (bd->group->bds_per_group == bds_per_group)
{
rtems_chain_extract (node);
return bd;
}
if (bd->group->users == 0)
{
/*
* We use the group to locate the start of the BDs for this group.
*/
rtems_bdbuf_group_realloc (bd->group, bds_per_group);
bd = (rtems_bdbuf_buffer*) rtems_chain_get (&bdbuf_cache.ready);
return bd;
}
node = rtems_chain_next (node);
}
return NULL;
}
/**
* Initialise the cache.
*
* @return rtems_status_code The initialisation status.
*/
rtems_status_code
rtems_bdbuf_init (void)
{
rtems_bdbuf_group* group;
rtems_bdbuf_buffer* bd;
uint8_t* buffer;
int b;
int cache_aligment;
rtems_status_code sc;
#if RTEMS_BDBUF_TRACE
rtems_bdbuf_printf ("init\n");
#endif
/*
* Check the configuration table values.
*/
if ((bdbuf_config.buffer_max % bdbuf_config.buffer_min) != 0)
return RTEMS_INVALID_NUMBER;
/*
* We use a special variable to manage the initialisation incase we have
* completing threads doing this. You may get errors if the another thread
* makes a call and we have not finished initialisation.
*/
if (bdbuf_cache.initialised)
return RTEMS_RESOURCE_IN_USE;
bdbuf_cache.initialised = true;
/*
* For unspecified cache alignments we use the CPU alignment.
*/
cache_aligment = 32; /* FIXME rtems_cache_get_data_line_size() */
if (cache_aligment <= 0)
cache_aligment = CPU_ALIGNMENT;
bdbuf_cache.sync_active = false;
bdbuf_cache.sync_device = -1;
bdbuf_cache.sync_requester = 0;
bdbuf_cache.tree = NULL;
rtems_chain_initialize_empty (&bdbuf_cache.swapout_workers);
rtems_chain_initialize_empty (&bdbuf_cache.ready);
rtems_chain_initialize_empty (&bdbuf_cache.lru);
rtems_chain_initialize_empty (&bdbuf_cache.modified);
rtems_chain_initialize_empty (&bdbuf_cache.sync);
bdbuf_cache.access = 0;
bdbuf_cache.access_waiters = 0;
bdbuf_cache.transfer = 0;
bdbuf_cache.transfer_waiters = 0;
bdbuf_cache.waiting = 0;
bdbuf_cache.wait_waiters = 0;
/*
* Create the locks for the cache.
*/
sc = rtems_semaphore_create (rtems_build_name ('B', 'D', 'C', 'l'),
1, RTEMS_BDBUF_CACHE_LOCK_ATTRIBS, 0,
&bdbuf_cache.lock);
if (sc != RTEMS_SUCCESSFUL)
{
bdbuf_cache.initialised = false;
return sc;
}
rtems_bdbuf_lock_cache ();
sc = rtems_semaphore_create (rtems_build_name ('B', 'D', 'C', 's'),
1, RTEMS_BDBUF_CACHE_LOCK_ATTRIBS, 0,
&bdbuf_cache.sync_lock);
if (sc != RTEMS_SUCCESSFUL)
{
rtems_bdbuf_unlock_cache ();
rtems_semaphore_delete (bdbuf_cache.lock);
bdbuf_cache.initialised = false;
return sc;
}
sc = rtems_semaphore_create (rtems_build_name ('B', 'D', 'C', 'a'),
0, RTEMS_BDBUF_CACHE_WAITER_ATTRIBS, 0,
&bdbuf_cache.access);
if (sc != RTEMS_SUCCESSFUL)
{
rtems_semaphore_delete (bdbuf_cache.sync_lock);
rtems_bdbuf_unlock_cache ();
rtems_semaphore_delete (bdbuf_cache.lock);
bdbuf_cache.initialised = false;
return sc;
}
sc = rtems_semaphore_create (rtems_build_name ('B', 'D', 'C', 't'),
0, RTEMS_BDBUF_CACHE_WAITER_ATTRIBS, 0,
&bdbuf_cache.transfer);
if (sc != RTEMS_SUCCESSFUL)
{
rtems_semaphore_delete (bdbuf_cache.access);
rtems_semaphore_delete (bdbuf_cache.sync_lock);
rtems_bdbuf_unlock_cache ();
rtems_semaphore_delete (bdbuf_cache.lock);
bdbuf_cache.initialised = false;
return sc;
}
sc = rtems_semaphore_create (rtems_build_name ('B', 'D', 'C', 'w'),
0, RTEMS_BDBUF_CACHE_WAITER_ATTRIBS, 0,
&bdbuf_cache.waiting);
if (sc != RTEMS_SUCCESSFUL)
{
rtems_semaphore_delete (bdbuf_cache.transfer);
rtems_semaphore_delete (bdbuf_cache.access);
rtems_semaphore_delete (bdbuf_cache.sync_lock);
rtems_bdbuf_unlock_cache ();
rtems_semaphore_delete (bdbuf_cache.lock);
bdbuf_cache.initialised = false;
return sc;
}
/*
* Allocate the memory for the buffer descriptors.
*/
bdbuf_cache.bds = calloc (sizeof (rtems_bdbuf_buffer),
bdbuf_config.size / bdbuf_config.buffer_min);
if (!bdbuf_cache.bds)
{
rtems_semaphore_delete (bdbuf_cache.transfer);
rtems_semaphore_delete (bdbuf_cache.access);
rtems_semaphore_delete (bdbuf_cache.sync_lock);
rtems_bdbuf_unlock_cache ();
rtems_semaphore_delete (bdbuf_cache.lock);
bdbuf_cache.initialised = false;
return RTEMS_NO_MEMORY;
}
/*
* Compute the various number of elements in the cache.
*/
bdbuf_cache.buffer_min_count =
bdbuf_config.size / bdbuf_config.buffer_min;
bdbuf_cache.max_bds_per_group =
bdbuf_config.buffer_max / bdbuf_config.buffer_min;
bdbuf_cache.group_count =
bdbuf_cache.buffer_min_count / bdbuf_cache.max_bds_per_group;
/*
* Allocate the memory for the buffer descriptors.
*/
bdbuf_cache.groups = calloc (sizeof (rtems_bdbuf_group),
bdbuf_cache.group_count);
if (!bdbuf_cache.groups)
{
free (bdbuf_cache.bds);
rtems_semaphore_delete (bdbuf_cache.transfer);
rtems_semaphore_delete (bdbuf_cache.access);
rtems_semaphore_delete (bdbuf_cache.sync_lock);
rtems_bdbuf_unlock_cache ();
rtems_semaphore_delete (bdbuf_cache.lock);
bdbuf_cache.initialised = false;
return RTEMS_NO_MEMORY;
}
/*
* Allocate memory for buffer memory. The buffer memory will be cache
* aligned. It is possible to free the memory allocated by rtems_memalign()
* with free(). Return 0 if allocated.
*/
if (rtems_memalign ((void **) &bdbuf_cache.buffers,
cache_aligment,
bdbuf_cache.buffer_min_count * bdbuf_config.buffer_min) != 0)
{
free (bdbuf_cache.groups);
free (bdbuf_cache.bds);
rtems_semaphore_delete (bdbuf_cache.transfer);
rtems_semaphore_delete (bdbuf_cache.access);
rtems_semaphore_delete (bdbuf_cache.sync_lock);
rtems_bdbuf_unlock_cache ();
rtems_semaphore_delete (bdbuf_cache.lock);
bdbuf_cache.initialised = false;
return RTEMS_NO_MEMORY;
}
/*
* The cache is empty after opening so we need to add all the buffers to it
* and initialise the groups.
*/
for (b = 0, group = bdbuf_cache.groups,
bd = bdbuf_cache.bds, buffer = bdbuf_cache.buffers;
b < bdbuf_cache.buffer_min_count;
b++, bd++, buffer += bdbuf_config.buffer_min)
{
bd->dev = -1;
bd->group = group;
bd->buffer = buffer;
bd->avl.left = NULL;
bd->avl.right = NULL;
bd->state = RTEMS_BDBUF_STATE_EMPTY;
bd->error = 0;
bd->waiters = 0;
bd->hold_timer = 0;
rtems_chain_append (&bdbuf_cache.ready, &bd->link);
if ((b % bdbuf_cache.max_bds_per_group) ==
(bdbuf_cache.max_bds_per_group - 1))
group++;
}
for (b = 0,
group = bdbuf_cache.groups,
bd = bdbuf_cache.bds;
b < bdbuf_cache.group_count;
b++,
group++,
bd += bdbuf_cache.max_bds_per_group)
{
group->bds_per_group = bdbuf_cache.max_bds_per_group;
group->users = 0;
group->bdbuf = bd;
}
/*
* Create and start swapout task. This task will create and manage the worker
* threads.
*/
bdbuf_cache.swapout_enabled = true;
sc = rtems_task_create (rtems_build_name('B', 'S', 'W', 'P'),
(bdbuf_config.swapout_priority ?
bdbuf_config.swapout_priority :
RTEMS_BDBUF_SWAPOUT_TASK_PRIORITY_DEFAULT),
SWAPOUT_TASK_STACK_SIZE,
RTEMS_PREEMPT | RTEMS_NO_TIMESLICE | RTEMS_NO_ASR,
RTEMS_LOCAL | RTEMS_NO_FLOATING_POINT,
&bdbuf_cache.swapout);
if (sc != RTEMS_SUCCESSFUL)
{
free (bdbuf_cache.buffers);
free (bdbuf_cache.groups);
free (bdbuf_cache.bds);
rtems_semaphore_delete (bdbuf_cache.transfer);
rtems_semaphore_delete (bdbuf_cache.access);
rtems_semaphore_delete (bdbuf_cache.sync_lock);
rtems_bdbuf_unlock_cache ();
rtems_semaphore_delete (bdbuf_cache.lock);
bdbuf_cache.initialised = false;
return sc;
}
sc = rtems_task_start (bdbuf_cache.swapout,
rtems_bdbuf_swapout_task,
(rtems_task_argument) &bdbuf_cache);
if (sc != RTEMS_SUCCESSFUL)
{
rtems_task_delete (bdbuf_cache.swapout);
free (bdbuf_cache.buffers);
free (bdbuf_cache.groups);
free (bdbuf_cache.bds);
rtems_semaphore_delete (bdbuf_cache.transfer);
rtems_semaphore_delete (bdbuf_cache.access);
rtems_semaphore_delete (bdbuf_cache.sync_lock);
rtems_bdbuf_unlock_cache ();
rtems_semaphore_delete (bdbuf_cache.lock);
bdbuf_cache.initialised = false;
return sc;
}
rtems_bdbuf_unlock_cache ();
return RTEMS_SUCCESSFUL;
}
/**
* Get a buffer for this device and block. This function returns a buffer once
* placed into the AVL tree. If no buffer is available and it is not a read
* ahead request and no buffers are waiting to the written to disk wait until a
* buffer is available. If buffers are waiting to be written to disk and none
* are available expire the hold timer's of the queued buffers and wake the
* swap out task. If the buffer is for a read ahead transfer return NULL if
* there are no buffers available or the buffer is already in the cache.
*
* The AVL tree of buffers for the cache is searched and if not found obtain a
* buffer and insert it into the AVL tree. Buffers are first obtained from the
* ready list until all empty/ready buffers are used. Once all buffers are in
* use the LRU list is searched for a buffer of the same group size or a group
* that has no active buffers in use. A buffer taken from the LRU list is
* removed from the AVL tree and assigned the new block number. The ready or
* LRU list buffer is initialised to this device and block. If no buffers are
* available due to the ready and LRU lists being empty a check is made of the
* modified list. Buffers may be queued waiting for the hold timer to
* expire. These buffers should be written to disk and returned to the LRU list
* where they can be used. If buffers are on the modified list the max. write
* block size of buffers have their hold timer's expired and the swap out task
* woken. The caller then blocks on the waiting semaphore and counter. When
* buffers return from the upper layers (access) or lower driver (transfer) the
* blocked caller task is woken and this procedure is repeated. The repeat
* handles a case of a another thread pre-empting getting a buffer first and
* adding it to the AVL tree.
*
* A buffer located in the AVL tree means it is already in the cache and maybe
* in use somewhere. The buffer can be either:
*
* # Cached. Not being accessed or part of a media transfer.
* # Access or modifed access. Is with an upper layer being accessed.
* # Transfer. Is with the driver and part of a media transfer.
*
* If cached we assign the new state, extract it from any list it maybe part of
* and return to the user.
*
* This function assumes the cache the buffer is being taken from is locked and
* it will make sure the cache is locked when it returns. The cache will be
* unlocked if the call could block.
*
* Variable sized buffer is handled by groups. A group is the size of the
* maximum buffer that can be allocated. The group can size in multiples of the
* minimum buffer size where the mulitples are 1,2,4,8, etc. If the buffer is
* found in the AVL tree the number of BDs in the group is check and if
* different the buffer size for the block has changed. The buffer needs to be
* invalidated.
*
* @param dd The disk device. Has the configured block size.
* @param bds_per_group The number of BDs in a group for this block.
* @param block Absolute media block number for the device
* @param read_ahead The get is for a read ahead buffer if true
* @return RTEMS status code (if operation completed successfully or error
* code if error is occured)
*/
static rtems_bdbuf_buffer*
rtems_bdbuf_get_buffer (rtems_disk_device* dd,
size_t bds_per_group,
rtems_blkdev_bnum block,
bool read_ahead)
{
dev_t device = dd->dev;
rtems_bdbuf_buffer* bd;
bool available;
/*
* Loop until we get a buffer. Under load we could find no buffers are
* available requiring this task to wait until some become available before
* proceeding. There is no timeout. If this call is to block and the buffer
* is for a read ahead buffer return NULL. The read ahead is nice but not
* that important.
*
* The search procedure is repeated as another thread could have pre-empted
* us while we waited for a buffer, obtained an empty buffer and loaded the
* AVL tree with the one we are after. In this case we move down and wait for
* the buffer to return to the cache.
*/
do
{
/*
* Search for buffer descriptor for this dev/block key.
*/
bd = rtems_bdbuf_avl_search (&bdbuf_cache.tree, device, block);
/*
* No buffer in the cache for this block. We need to obtain a buffer and
* this means take a buffer that is ready to use. If all buffers are in use
* take the least recently used buffer. If there are none then the cache is
* empty. All the buffers are either queued to be written to disk or with
* the user. We cannot do much with the buffers with the user how-ever with
* the modified buffers waiting to be written to disk flush the maximum
* number transfered in a block to disk. After this all that can be done is
* to wait for a buffer to return to the cache.
*/
if (!bd)
{
/*
* Assign new buffer descriptor from the ready list if one is present. If
* the ready queue is empty get the oldest buffer from LRU list. If the
* LRU list is empty there are no available buffers check the modified
* list.
*/
bd = rtems_bdbuf_get_next_bd (bds_per_group, &bdbuf_cache.ready);
if (!bd)
{
/*
* No unused or read-ahead buffers.
*
* If this is a read ahead buffer just return. No need to place further
* pressure on the cache by reading something that may be needed when
* we have data in the cache that was needed and may still be in the
* future.
*/
if (read_ahead)
return NULL;
/*
* Check the LRU list.
*/
bd = rtems_bdbuf_get_next_bd (bds_per_group, &bdbuf_cache.lru);
if (bd)
{
/*
* Remove the buffer from the AVL tree.
*/
if (rtems_bdbuf_avl_remove (&bdbuf_cache.tree, bd) != 0)
rtems_fatal_error_occurred (RTEMS_BLKDEV_FATAL_BDBUF_CONSISTENCY_2);
}
else
{
/*
* If there are buffers on the modified list expire the hold timer
* and wake the swap out task then wait else just go and wait.
*
* The check for an empty list is made so the swapper is only woken
* when if timers are changed.
*/
if (!rtems_chain_is_empty (&bdbuf_cache.modified))
{
rtems_chain_node* node = rtems_chain_first (&bdbuf_cache.modified);
uint32_t write_blocks = 0;
while ((write_blocks < bdbuf_config.max_write_blocks) &&
!rtems_chain_is_tail (&bdbuf_cache.modified, node))
{
rtems_bdbuf_buffer* bd = (rtems_bdbuf_buffer*) node;
bd->hold_timer = 0;
write_blocks++;
node = rtems_chain_next (node);
}
rtems_bdbuf_wake_swapper ();
}
/*
* Wait for a buffer to be returned to the cache. The buffer will be
* placed on the LRU list.
*/
rtems_bdbuf_wait (&bdbuf_cache.waiting, &bdbuf_cache.wait_waiters);
}
}
else
{
/*
* We have a new buffer for this block.
*/
if ((bd->state != RTEMS_BDBUF_STATE_EMPTY) &&
(bd->state != RTEMS_BDBUF_STATE_READ_AHEAD))
rtems_fatal_error_occurred (RTEMS_BLKDEV_FATAL_BDBUF_CONSISTENCY_3);
if (bd->state == RTEMS_BDBUF_STATE_READ_AHEAD)
{
if (rtems_bdbuf_avl_remove (&bdbuf_cache.tree, bd) != 0)
rtems_fatal_error_occurred (RTEMS_BLKDEV_FATAL_BDBUF_CONSISTENCY_4);
}
}
if (bd)
{
bd->dev = device;
bd->block = block;
bd->avl.left = NULL;
bd->avl.right = NULL;
bd->state = RTEMS_BDBUF_STATE_EMPTY;
bd->error = 0;
bd->waiters = 0;
if (rtems_bdbuf_avl_insert (&bdbuf_cache.tree, bd) != 0)
rtems_fatal_error_occurred (RTEMS_BLKDEV_FATAL_BDBUF_CONSISTENCY_5);
return bd;
}
}
else
{
/*
* We have the buffer for the block from the cache. Check if the buffer
* in the cache is the same size and the requested size we are after.
*/
if (bd->group->bds_per_group != bds_per_group)
{
bd->state = RTEMS_BDBUF_STATE_EMPTY;
rtems_chain_extract (&bd->link);
rtems_chain_prepend (&bdbuf_cache.ready, &bd->link);
bd = NULL;
}
}
}
while (!bd);
/*
* If the buffer is for read ahead and it exists in the AVL cache or is being
* accessed or being transfered then return NULL.
*/
if (read_ahead)
return NULL;
/*
* Loop waiting for the buffer to enter the cached state. If the buffer is in
* the access or transfer state then wait until it is not.
*/
available = false;
while (!available)
{
switch (bd->state)
{
case RTEMS_BDBUF_STATE_CACHED:
case RTEMS_BDBUF_STATE_MODIFIED:
case RTEMS_BDBUF_STATE_READ_AHEAD:
available = true;
break;
case RTEMS_BDBUF_STATE_ACCESS:
case RTEMS_BDBUF_STATE_ACCESS_MODIFIED:
bd->waiters++;
rtems_bdbuf_wait (&bdbuf_cache.access,
&bdbuf_cache.access_waiters);
bd->waiters--;
break;
case RTEMS_BDBUF_STATE_SYNC:
case RTEMS_BDBUF_STATE_TRANSFER:
bd->waiters++;
rtems_bdbuf_wait (&bdbuf_cache.transfer,
&bdbuf_cache.transfer_waiters);
bd->waiters--;
break;
default:
rtems_fatal_error_occurred (RTEMS_BLKDEV_FATAL_BDBUF_CONSISTENCY_6);
}
}
/*
* Buffer is linked to the LRU, modifed, or sync lists. Remove it from there.
*/
rtems_chain_extract (&bd->link);
return bd;
}
rtems_status_code
rtems_bdbuf_get (dev_t device,
rtems_blkdev_bnum block,
rtems_bdbuf_buffer** bdp)
{
rtems_disk_device* dd;
rtems_bdbuf_buffer* bd;
size_t bds_per_group;
if (!bdbuf_cache.initialised)
return RTEMS_NOT_CONFIGURED;
/*
* Do not hold the cache lock when obtaining the disk table.
*/
dd = rtems_disk_obtain (device);
if (!dd)
return RTEMS_INVALID_ID;
if (block >= dd->size)
{
rtems_disk_release (dd);
return RTEMS_INVALID_ADDRESS;
}
bds_per_group = rtems_bdbuf_bds_per_group (dd->block_size);
if (!bds_per_group)
{
rtems_disk_release (dd);
return RTEMS_INVALID_NUMBER;
}
rtems_bdbuf_lock_cache ();
#if RTEMS_BDBUF_TRACE
/* Print the block index relative to the physical disk */
rtems_bdbuf_printf ("get: %d (dev = %08x)\n", block + dd->start, device);
#endif
bd = rtems_bdbuf_get_buffer (dd, bds_per_group, block + dd->start, false);
if (bd->state == RTEMS_BDBUF_STATE_MODIFIED)
bd->state = RTEMS_BDBUF_STATE_ACCESS_MODIFIED;
else
bd->state = RTEMS_BDBUF_STATE_ACCESS;
/*
* Indicate a buffer in this group is being used.
*/
bd->group->users++;
rtems_bdbuf_unlock_cache ();
rtems_disk_release(dd);
*bdp = bd;
return RTEMS_SUCCESSFUL;
}
/**
* Call back handler called by the low level driver when the transfer has
* completed. This function may be invoked from interrupt handler.
*
* @param arg Arbitrary argument specified in block device request
* structure (in this case - pointer to the appropriate
* block device request structure).
* @param status I/O completion status
* @param error errno error code if status != RTEMS_SUCCESSFUL
*/
static void
rtems_bdbuf_read_done (void* arg, rtems_status_code status, int error)
{
rtems_blkdev_request* req = (rtems_blkdev_request*) arg;
req->error = error;
req->status = status;
rtems_event_send (req->io_task, RTEMS_BDBUF_TRANSFER_SYNC);
}
rtems_status_code
rtems_bdbuf_read (dev_t device,
rtems_blkdev_bnum block,
rtems_bdbuf_buffer** bdp)
{
rtems_disk_device* dd;
rtems_bdbuf_buffer* bd = NULL;
uint32_t read_ahead_count;
rtems_blkdev_request* req;
size_t bds_per_group;
if (!bdbuf_cache.initialised)
return RTEMS_NOT_CONFIGURED;
/*
* @todo This type of request structure is wrong and should be removed.
*/
#define bdbuf_alloc(size) __builtin_alloca (size)
req = bdbuf_alloc (sizeof (rtems_blkdev_request) +
(sizeof ( rtems_blkdev_sg_buffer) *
rtems_bdbuf_configuration.max_read_ahead_blocks));
/*
* Do not hold the cache lock when obtaining the disk table.
*/
dd = rtems_disk_obtain (device);
if (!dd)
return RTEMS_INVALID_ID;
if (block >= dd->size) {
rtems_disk_release(dd);
return RTEMS_INVALID_NUMBER;
}
bds_per_group = rtems_bdbuf_bds_per_group (dd->block_size);
if (!bds_per_group)
{
rtems_disk_release (dd);
return RTEMS_INVALID_NUMBER;
}
#if RTEMS_BDBUF_TRACE
/* Print the block index relative to the physical disk */
rtems_bdbuf_printf ("read: %d (dev = %08x)\n", block + dd->start, device);
#endif
req->bufnum = 0;
/*
* Read the block plus the required number of blocks ahead. The number of
* blocks to read ahead is configured by the user and limited by the size of
* the disk or reaching a read ahead block that is also cached.
*
* Limit the blocks read by the size of the disk.
*/
if ((rtems_bdbuf_configuration.max_read_ahead_blocks + block) < dd->size)
read_ahead_count = rtems_bdbuf_configuration.max_read_ahead_blocks;
else
read_ahead_count = dd->size - block;
rtems_bdbuf_lock_cache ();
while (req->bufnum < read_ahead_count)
{
/*
* Get the buffer for the requested block. If the block is cached then
* return it. If it is not cached transfer the block from the disk media
* into memory.
*
* We need to clean up any buffers allocated and not passed back to the
* caller.
*/
bd = rtems_bdbuf_get_buffer (dd, bds_per_group,
block + dd->start + req->bufnum,
req->bufnum == 0 ? false : true);
/*
* Read ahead buffer is in the cache or none available. Read what we
* can.
*/
if (!bd)
break;
/*
* Is the block we are interested in the cache ?
*/
if ((bd->state == RTEMS_BDBUF_STATE_CACHED) ||
(bd->state == RTEMS_BDBUF_STATE_MODIFIED))
break;
bd->state = RTEMS_BDBUF_STATE_TRANSFER;
bd->error = 0;
/*
* The buffer will be passed to the driver so this buffer has a user.
*/
bd->group->users++;
/*
* @todo The use of these req blocks is not a great design. The req is a
* struct with a single 'bufs' declared in the req struct and the
* others are added in the outer level struct. This relies on the
* structs joining as a single array and that assumes the compiler
* packs the structs. Why not just place on a list ? The BD has a
* node that can be used.
*/
req->bufs[req->bufnum].user = bd;
req->bufs[req->bufnum].block = bd->block;
req->bufs[req->bufnum].length = dd->block_size;
req->bufs[req->bufnum].buffer = bd->buffer;
req->bufnum++;
}
/*
* Transfer any requested buffers. If the request count is 0 we have found
* the block in the cache so return it.
*/
if (req->bufnum)
{
/*
* Unlock the cache. We have the buffer for the block and it will be in the
* access or transfer state. We may also have a number of read ahead blocks
* if we need to transfer data. At this point any other threads can gain
* access to the cache and if they are after any of the buffers we have
* they will block and be woken when the buffer is returned to the cache.
*
* If a transfer is needed the I/O operation will occur with pre-emption
* enabled and the cache unlocked. This is a change to the previous version
* of the bdbuf code.
*/
rtems_event_set out;
int result;
uint32_t b;
/*
* Flush any events.
*/
rtems_event_receive (RTEMS_BDBUF_TRANSFER_SYNC,
RTEMS_EVENT_ALL | RTEMS_NO_WAIT,
0, &out);
rtems_bdbuf_unlock_cache ();
req->req = RTEMS_BLKDEV_REQ_READ;
req->req_done = rtems_bdbuf_read_done;
req->done_arg = req;
req->io_task = rtems_task_self ();
req->status = RTEMS_RESOURCE_IN_USE;
req->error = 0;
result = dd->ioctl (dd->phys_dev->dev, RTEMS_BLKIO_REQUEST, req);
/*
* Inspection of the DOS FS code shows the result from this function is
* handled and a buffer must be returned.
*/
if (result < 0)
{
req->error = errno;
req->status = RTEMS_IO_ERROR;
}
else
{
rtems_status_code sc;
sc = rtems_event_receive (RTEMS_BDBUF_TRANSFER_SYNC,
RTEMS_EVENT_ALL | RTEMS_WAIT,
0, &out);
if (sc != RTEMS_SUCCESSFUL)
rtems_fatal_error_occurred (BLKDEV_FATAL_BDBUF_SWAPOUT_RE);
}
rtems_bdbuf_lock_cache ();
for (b = 1; b < req->bufnum; b++)
{
bd = req->bufs[b].user;
bd->error = req->error;
bd->state = RTEMS_BDBUF_STATE_READ_AHEAD;
bd->group->users--;
rtems_chain_prepend (&bdbuf_cache.ready, &bd->link);
/*
* If there is an error remove the BD from the AVL tree as it does is
* invalid, then wake any threads that may be waiting. A thread may have
* been waiting for this block and assumed it was in the tree.
*/
if (bd->error)
{
bd->state = RTEMS_BDBUF_STATE_EMPTY;
if (rtems_bdbuf_avl_remove (&bdbuf_cache.tree, bd) != 0)
rtems_fatal_error_occurred (RTEMS_BLKDEV_FATAL_BDBUF_CONSISTENCY_9);
}
if (bd->waiters)
rtems_bdbuf_wake (bdbuf_cache.access, &bdbuf_cache.access_waiters);
else
{
if (rtems_chain_has_only_one_node (&bdbuf_cache.ready))
rtems_bdbuf_wake (bdbuf_cache.waiting, &bdbuf_cache.wait_waiters);
}
}
bd = req->bufs[0].user;
/*
* One less user. We do this here then increment again so the case of the
* buffer in the the cache and no read leaves the user counts at the
* correct level.
*/
bd->group->users--;
}
/*
* The data for this block is cached in the buffer.
*/
if (bd->state == RTEMS_BDBUF_STATE_MODIFIED)
bd->state = RTEMS_BDBUF_STATE_ACCESS_MODIFIED;
else
{
/*
* The file system is a user of the buffer.
*/
bd->group->users++;
bd->state = RTEMS_BDBUF_STATE_ACCESS;
}
rtems_bdbuf_unlock_cache ();
rtems_disk_release (dd);
*bdp = bd;
return RTEMS_SUCCESSFUL;
}
rtems_status_code
rtems_bdbuf_release (rtems_bdbuf_buffer* bd)
{
if (!bdbuf_cache.initialised)
return RTEMS_NOT_CONFIGURED;
if (bd == NULL)
return RTEMS_INVALID_ADDRESS;
rtems_bdbuf_lock_cache ();
#if RTEMS_BDBUF_TRACE
rtems_bdbuf_printf ("release: %d\n", bd->block);
#endif
if (bd->state == RTEMS_BDBUF_STATE_ACCESS_MODIFIED)
{
rtems_bdbuf_append_modified (bd);
}
else
{
/*
* If this is a read ahead buffer place the ready queue. Buffers are taken
* from here first. If we prepend then get from the queue the buffers
* furthermost from the read buffer will be used.
*/
if (bd->state == RTEMS_BDBUF_STATE_READ_AHEAD)
rtems_chain_prepend (&bdbuf_cache.ready, &bd->link);
else
{
bd->state = RTEMS_BDBUF_STATE_CACHED;
rtems_chain_append (&bdbuf_cache.lru, &bd->link);
}
/*
* One less user for the group of bds.
*/
bd->group->users--;
}
/*
* If there are threads waiting to access the buffer wake them. Wake any
* waiters if this is the first buffer to placed back onto the queue.
*/
if (bd->waiters)
rtems_bdbuf_wake (bdbuf_cache.access, &bdbuf_cache.access_waiters);
else
{
if (bd->state == RTEMS_BDBUF_STATE_READ_AHEAD)
{
if (rtems_chain_has_only_one_node (&bdbuf_cache.ready))
rtems_bdbuf_wake (bdbuf_cache.waiting, &bdbuf_cache.wait_waiters);
}
else
{
if (rtems_chain_has_only_one_node (&bdbuf_cache.lru))
rtems_bdbuf_wake (bdbuf_cache.waiting, &bdbuf_cache.wait_waiters);
}
}
rtems_bdbuf_unlock_cache ();
return RTEMS_SUCCESSFUL;
}
rtems_status_code
rtems_bdbuf_release_modified (rtems_bdbuf_buffer* bd)
{
if (!bdbuf_cache.initialised)
return RTEMS_NOT_CONFIGURED;
if (!bd)
return RTEMS_INVALID_ADDRESS;
rtems_bdbuf_lock_cache ();
#if RTEMS_BDBUF_TRACE
rtems_bdbuf_printf ("release modified: %d\n", bd->block);
#endif
bd->hold_timer = rtems_bdbuf_configuration.swap_block_hold;
rtems_bdbuf_append_modified (bd);
if (bd->waiters)
rtems_bdbuf_wake (bdbuf_cache.access, &bdbuf_cache.access_waiters);
rtems_bdbuf_unlock_cache ();
return RTEMS_SUCCESSFUL;
}
rtems_status_code
rtems_bdbuf_sync (rtems_bdbuf_buffer* bd)
{
bool available;
#if RTEMS_BDBUF_TRACE
rtems_bdbuf_printf ("sync: %d\n", bd->block);
#endif
if (!bdbuf_cache.initialised)
return RTEMS_NOT_CONFIGURED;
if (!bd)
return RTEMS_INVALID_ADDRESS;
rtems_bdbuf_lock_cache ();
bd->state = RTEMS_BDBUF_STATE_SYNC;
rtems_chain_append (&bdbuf_cache.sync, &bd->link);
rtems_bdbuf_wake_swapper ();
available = false;
while (!available)
{
switch (bd->state)
{
case RTEMS_BDBUF_STATE_CACHED:
case RTEMS_BDBUF_STATE_READ_AHEAD:
case RTEMS_BDBUF_STATE_MODIFIED:
case RTEMS_BDBUF_STATE_ACCESS:
case RTEMS_BDBUF_STATE_ACCESS_MODIFIED:
available = true;
break;
case RTEMS_BDBUF_STATE_SYNC:
case RTEMS_BDBUF_STATE_TRANSFER:
bd->waiters++;
rtems_bdbuf_wait (&bdbuf_cache.transfer,
&bdbuf_cache.transfer_waiters);
bd->waiters--;
break;
default:
rtems_fatal_error_occurred (RTEMS_BLKDEV_FATAL_BDBUF_CONSISTENCY_7);
}
}
rtems_bdbuf_unlock_cache ();
return RTEMS_SUCCESSFUL;
}
rtems_status_code
rtems_bdbuf_syncdev (dev_t dev)
{
rtems_disk_device* dd;
rtems_status_code sc;
rtems_event_set out;
#if RTEMS_BDBUF_TRACE
rtems_bdbuf_printf ("syncdev: %08x\n", dev);
#endif
if (!bdbuf_cache.initialised)
return RTEMS_NOT_CONFIGURED;
/*
* Do not hold the cache lock when obtaining the disk table.
*/
dd = rtems_disk_obtain (dev);
if (!dd)
return RTEMS_INVALID_ID;
/*
* Take the sync lock before locking the cache. Once we have the sync lock we
* can lock the cache. If another thread has the sync lock it will cause this
* thread to block until it owns the sync lock then it can own the cache. The
* sync lock can only be obtained with the cache unlocked.
*/
rtems_bdbuf_lock_sync ();
rtems_bdbuf_lock_cache ();
/*
* Set the cache to have a sync active for a specific device and let the swap
* out task know the id of the requester to wake when done.
*
* The swap out task will negate the sync active flag when no more buffers
* for the device are held on the "modified for sync" queues.
*/
bdbuf_cache.sync_active = true;
bdbuf_cache.sync_requester = rtems_task_self ();
bdbuf_cache.sync_device = dev;
rtems_bdbuf_wake_swapper ();
rtems_bdbuf_unlock_cache ();
sc = rtems_event_receive (RTEMS_BDBUF_TRANSFER_SYNC,
RTEMS_EVENT_ALL | RTEMS_WAIT,
0, &out);
if (sc != RTEMS_SUCCESSFUL)
rtems_fatal_error_occurred (BLKDEV_FATAL_BDBUF_SWAPOUT_RE);
rtems_bdbuf_unlock_sync ();
return rtems_disk_release (dd);
}
/**
* Call back handler called by the low level driver when the transfer has
* completed. This function may be invoked from interrupt handler.
*
* @param arg Arbitrary argument specified in block device request
* structure (in this case - pointer to the appropriate
* block device request structure).
* @param status I/O completion status
* @param error errno error code if status != RTEMS_SUCCESSFUL
*/
static void
rtems_bdbuf_write_done(void *arg, rtems_status_code status, int error)
{
rtems_blkdev_request* req = (rtems_blkdev_request*) arg;
req->error = error;
req->status = status;
rtems_event_send (req->io_task, RTEMS_BDBUF_TRANSFER_SYNC);
}
/**
* Swapout transfer to the driver. The driver will break this I/O into groups
* of consecutive write requests is multiple consecutive buffers are required
* by the driver.
*
* @param transfer The transfer transaction.
*/
static void
rtems_bdbuf_swapout_write (rtems_bdbuf_swapout_transfer* transfer)
{
rtems_disk_device* dd;
#if RTEMS_BDBUF_TRACE
rtems_bdbuf_printf ("swapout transfer: %08x\n", transfer->dev);
#endif
/*
* If there are buffers to transfer to the media transfer them.
*/
if (!rtems_chain_is_empty (&transfer->bds))
{
/*
* Obtain the disk device. The cache's mutex has been released to avoid a
* dead lock.
*/
dd = rtems_disk_obtain (transfer->dev);
if (dd)
{
/*
* The last block number used when the driver only supports
* continuous blocks in a single request.
*/
uint32_t last_block = 0;
/*
* Take as many buffers as configured and pass to the driver. Note, the
* API to the drivers has an array of buffers and if a chain was passed
* we could have just passed the list. If the driver API is updated it
* should be possible to make this change with little effect in this
* code. The array that is passed is broken in design and should be
* removed. Merging members of a struct into the first member is
* trouble waiting to happen.
*/
transfer->write_req->status = RTEMS_RESOURCE_IN_USE;
transfer->write_req->error = 0;
transfer->write_req->bufnum = 0;
while (!rtems_chain_is_empty (&transfer->bds))
{
rtems_bdbuf_buffer* bd =
(rtems_bdbuf_buffer*) rtems_chain_get (&transfer->bds);
bool write = false;
/*
* If the device only accepts sequential buffers and this is not the
* first buffer (the first is always sequential, and the buffer is not
* sequential then put the buffer back on the transfer chain and write
* the committed buffers.
*/
#if RTEMS_BDBUF_TRACE
rtems_bdbuf_printf ("swapout write: bd:%d, bufnum:%d mode:%s\n",
bd->block, transfer->write_req->bufnum,
dd->phys_dev->capabilities &
RTEMS_BLKDEV_CAP_MULTISECTOR_CONT ? "MULIT" : "SCAT");
#endif
if ((dd->phys_dev->capabilities & RTEMS_BLKDEV_CAP_MULTISECTOR_CONT) &&
transfer->write_req->bufnum &&
(bd->block != (last_block + 1)))
{
rtems_chain_prepend (&transfer->bds, &bd->link);
write = true;
}
else
{
rtems_blkdev_sg_buffer* buf;
buf = &transfer->write_req->bufs[transfer->write_req->bufnum];
transfer->write_req->bufnum++;
buf->user = bd;
buf->block = bd->block;
buf->length = dd->block_size;
buf->buffer = bd->buffer;
last_block = bd->block;
}
/*
* Perform the transfer if there are no more buffers, or the transfer
* size has reached the configured max. value.
*/
if (rtems_chain_is_empty (&transfer->bds) ||
(transfer->write_req->bufnum >= rtems_bdbuf_configuration.max_write_blocks))
write = true;
if (write)
{
int result;
uint32_t b;
#if RTEMS_BDBUF_TRACE
rtems_bdbuf_printf ("swapout write: writing bufnum:%d\n",
transfer->write_req->bufnum);
#endif
/*
* Perform the transfer. No cache locks, no preemption, only the disk
* device is being held.
*/
result = dd->phys_dev->ioctl (dd->phys_dev->dev,
RTEMS_BLKIO_REQUEST, transfer->write_req);
if (result < 0)
{
rtems_bdbuf_lock_cache ();
for (b = 0; b < transfer->write_req->bufnum; b++)
{
bd = transfer->write_req->bufs[b].user;
bd->state = RTEMS_BDBUF_STATE_MODIFIED;
bd->error = errno;
/*
* Place back on the cache's modified queue and try again.
*
* @warning Not sure this is the best option but I do not know
* what else can be done.
*/
rtems_chain_append (&bdbuf_cache.modified, &bd->link);
}
}
else
{
rtems_status_code sc = 0;
rtems_event_set out;
sc = rtems_event_receive (RTEMS_BDBUF_TRANSFER_SYNC,
RTEMS_EVENT_ALL | RTEMS_WAIT,
0, &out);
if (sc != RTEMS_SUCCESSFUL)
rtems_fatal_error_occurred (BLKDEV_FATAL_BDBUF_SWAPOUT_RE);
rtems_bdbuf_lock_cache ();
for (b = 0; b < transfer->write_req->bufnum; b++)
{
bd = transfer->write_req->bufs[b].user;
bd->state = RTEMS_BDBUF_STATE_CACHED;
bd->error = 0;
/*
* The buffer is now not modified so lower the user count for the group.
*/
bd->group->users--;
rtems_chain_append (&bdbuf_cache.lru, &bd->link);
if (bd->waiters)
rtems_bdbuf_wake (bdbuf_cache.transfer, &bdbuf_cache.transfer_waiters);
else
{
if (rtems_chain_has_only_one_node (&bdbuf_cache.lru))
rtems_bdbuf_wake (bdbuf_cache.waiting, &bdbuf_cache.wait_waiters);
}
}
}
rtems_bdbuf_unlock_cache ();
transfer->write_req->status = RTEMS_RESOURCE_IN_USE;
transfer->write_req->error = 0;
transfer->write_req->bufnum = 0;
}
}
rtems_disk_release (dd);
}
else
{
/*
* We have buffers but no device. Put the BDs back onto the
* ready queue and exit.
*/
/* @todo fixme */
}
}
}
/**
* Process the modified list of buffers. There is a sync or modified list that
* needs to be handled so we have a common function to do the work.
*
* @param dev The device to handle. If -1 no device is selected so select the
* device of the first buffer to be written to disk.
* @param chain The modified chain to process.
* @param transfer The chain to append buffers to be written too.
* @param sync_active If true this is a sync operation so expire all timers.
* @param update_timers If true update the timers.
* @param timer_delta It update_timers is true update the timers by this
* amount.
*/
static void
rtems_bdbuf_swapout_modified_processing (dev_t* dev,
rtems_chain_control* chain,
rtems_chain_control* transfer,
bool sync_active,
bool update_timers,
uint32_t timer_delta)
{
if (!rtems_chain_is_empty (chain))
{
rtems_chain_node* node = rtems_chain_head (chain);
node = node->next;
while (!rtems_chain_is_tail (chain, node))
{
rtems_bdbuf_buffer* bd = (rtems_bdbuf_buffer*) node;
/*
* Check if the buffer's hold timer has reached 0. If a sync is active
* force all the timers to 0.
*
* @note Lots of sync requests will skew this timer. It should be based
* on TOD to be accurate. Does it matter ?
*/
if (sync_active)
bd->hold_timer = 0;
if (bd->hold_timer)
{
if (update_timers)
{
if (bd->hold_timer > timer_delta)
bd->hold_timer -= timer_delta;
else
bd->hold_timer = 0;
}
if (bd->hold_timer)
{
node = node->next;
continue;
}
}
/*
* This assumes we can set dev_t to -1 which is just an
* assumption. Cannot use the transfer list being empty the sync dev
* calls sets the dev to use.
*/
if (*dev == (dev_t)-1)
*dev = bd->dev;
if (bd->dev == *dev)
{
rtems_chain_node* next_node = node->next;
rtems_chain_node* tnode = rtems_chain_tail (transfer);
/*
* The blocks on the transfer list are sorted in block order. This
* means multi-block transfers for drivers that require consecutive
* blocks perform better with sorted blocks and for real disks it may
* help lower head movement.
*/
bd->state = RTEMS_BDBUF_STATE_TRANSFER;
rtems_chain_extract (node);
tnode = tnode->previous;
while (node && !rtems_chain_is_head (transfer, tnode))
{
rtems_bdbuf_buffer* tbd = (rtems_bdbuf_buffer*) tnode;
if (bd->block > tbd->block)
{
rtems_chain_insert (tnode, node);
node = NULL;
}
else
tnode = tnode->previous;
}
if (node)
rtems_chain_prepend (transfer, node);
node = next_node;
}
else
{
node = node->next;
}
}
}
}
/**
* Process the cache's modified buffers. Check the sync list first then the
* modified list extracting the buffers suitable to be written to disk. We have
* a device at a time. The task level loop will repeat this operation while
* there are buffers to be written. If the transfer fails place the buffers
* back on the modified list and try again later. The cache is unlocked while
* the buffers are being written to disk.
*
* @param timer_delta It update_timers is true update the timers by this
* amount.
* @param update_timers If true update the timers.
* @param transfer The transfer transaction data.
*
* @retval true Buffers where written to disk so scan again.
* @retval false No buffers where written to disk.
*/
static bool
rtems_bdbuf_swapout_processing (unsigned long timer_delta,
bool update_timers,
rtems_bdbuf_swapout_transfer* transfer)
{
rtems_bdbuf_swapout_worker* worker;
bool transfered_buffers = false;
rtems_bdbuf_lock_cache ();
/*
* If a sync is active do not use a worker because the current code does not
* cleaning up after. We need to know the buffers have been written when
* syncing to release sync lock and currently worker threads do not return to
* here. We do not know the worker is the last in a sequence of sync writes
* until after we have it running so we do not know to tell it to release the
* lock. The simplest solution is to get the main swap out task perform all
* sync operations.
*/
if (bdbuf_cache.sync_active)
worker = NULL;
else
{
worker = (rtems_bdbuf_swapout_worker*)
rtems_chain_get (&bdbuf_cache.swapout_workers);
if (worker)
transfer = &worker->transfer;
}
rtems_chain_initialize_empty (&transfer->bds);
transfer->dev = -1;
/*
* When the sync is for a device limit the sync to that device. If the sync
* is for a buffer handle process the devices in the order on the sync
* list. This means the dev is -1.
*/
if (bdbuf_cache.sync_active)
transfer->dev = bdbuf_cache.sync_device;
/*
* If we have any buffers in the sync queue move them to the modified
* list. The first sync buffer will select the device we use.
*/
rtems_bdbuf_swapout_modified_processing (&transfer->dev,
&bdbuf_cache.sync,
&transfer->bds,
true, false,
timer_delta);
/*
* Process the cache's modified list.
*/
rtems_bdbuf_swapout_modified_processing (&transfer->dev,
&bdbuf_cache.modified,
&transfer->bds,
bdbuf_cache.sync_active,
update_timers,
timer_delta);
/*
* We have all the buffers that have been modified for this device so the
* cache can be unlocked because the state of each buffer has been set to
* TRANSFER.
*/
rtems_bdbuf_unlock_cache ();
/*
* If there are buffers to transfer to the media transfer them.
*/
if (!rtems_chain_is_empty (&transfer->bds))
{
if (worker)
{
rtems_status_code sc = rtems_event_send (worker->id,
RTEMS_BDBUF_SWAPOUT_SYNC);
if (sc != RTEMS_SUCCESSFUL)
rtems_fatal_error_occurred (RTEMS_BLKDEV_FATAL_BDBUF_SO_WAKE);
}
else
{
rtems_bdbuf_swapout_write (transfer);
}
transfered_buffers = true;
}
if (bdbuf_cache.sync_active && !transfered_buffers)
{
rtems_id sync_requester;
rtems_bdbuf_lock_cache ();
sync_requester = bdbuf_cache.sync_requester;
bdbuf_cache.sync_active = false;
bdbuf_cache.sync_requester = 0;
rtems_bdbuf_unlock_cache ();
if (sync_requester)
rtems_event_send (sync_requester, RTEMS_BDBUF_TRANSFER_SYNC);
}
return transfered_buffers;
}
/**
* Allocate the write request and initialise it for good measure.
*
* @return rtems_blkdev_request* The write reference memory.
*/
static rtems_blkdev_request*
rtems_bdbuf_swapout_writereq_alloc (void)
{
/*
* @note chrisj The rtems_blkdev_request and the array at the end is a hack.
* I am disappointment at finding code like this in RTEMS. The request should
* have been a rtems_chain_control. Simple, fast and less storage as the node
* is already part of the buffer structure.
*/
rtems_blkdev_request* write_req =
malloc (sizeof (rtems_blkdev_request) +
(rtems_bdbuf_configuration.max_write_blocks *
sizeof (rtems_blkdev_sg_buffer)));
if (!write_req)
rtems_fatal_error_occurred (RTEMS_BLKDEV_FATAL_BDBUF_SO_NOMEM);
write_req->req = RTEMS_BLKDEV_REQ_WRITE;
write_req->req_done = rtems_bdbuf_write_done;
write_req->done_arg = write_req;
write_req->io_task = rtems_task_self ();
return write_req;
}
/**
* The swapout worker thread body.
*
* @param arg A pointer to the worker thread's private data.
* @return rtems_task Not used.
*/
static rtems_task
rtems_bdbuf_swapout_worker_task (rtems_task_argument arg)
{
rtems_bdbuf_swapout_worker* worker = (rtems_bdbuf_swapout_worker*) arg;
while (worker->enabled)
{
rtems_event_set out;
rtems_status_code sc;
sc = rtems_event_receive (RTEMS_BDBUF_SWAPOUT_SYNC,
RTEMS_EVENT_ALL | RTEMS_WAIT,
RTEMS_NO_TIMEOUT,
&out);
if (sc != RTEMS_SUCCESSFUL)
rtems_fatal_error_occurred (BLKDEV_FATAL_BDBUF_SWAPOUT_RE);
rtems_bdbuf_swapout_write (&worker->transfer);
rtems_bdbuf_lock_cache ();
rtems_chain_initialize_empty (&worker->transfer.bds);
worker->transfer.dev = -1;
rtems_chain_append (&bdbuf_cache.swapout_workers, &worker->link);
rtems_bdbuf_unlock_cache ();
}
free (worker->transfer.write_req);
free (worker);
rtems_task_delete (RTEMS_SELF);
}
/**
* Open the swapout worker threads.
*/
static void
rtems_bdbuf_swapout_workers_open (void)
{
rtems_status_code sc;
int w;
rtems_bdbuf_lock_cache ();
for (w = 0; w < rtems_bdbuf_configuration.swapout_workers; w++)
{
rtems_bdbuf_swapout_worker* worker;
worker = malloc (sizeof (rtems_bdbuf_swapout_worker));
if (!worker)
rtems_fatal_error_occurred (RTEMS_BLKDEV_FATAL_BDBUF_SO_NOMEM);
rtems_chain_append (&bdbuf_cache.swapout_workers, &worker->link);
worker->enabled = true;
worker->transfer.write_req = rtems_bdbuf_swapout_writereq_alloc ();
rtems_chain_initialize_empty (&worker->transfer.bds);
worker->transfer.dev = -1;
sc = rtems_task_create (rtems_build_name('B', 'D', 'o', 'a' + w),
(rtems_bdbuf_configuration.swapout_priority ?
rtems_bdbuf_configuration.swapout_priority :
RTEMS_BDBUF_SWAPOUT_TASK_PRIORITY_DEFAULT),
SWAPOUT_TASK_STACK_SIZE,
RTEMS_PREEMPT | RTEMS_NO_TIMESLICE | RTEMS_NO_ASR,
RTEMS_LOCAL | RTEMS_NO_FLOATING_POINT,
&worker->id);
if (sc != RTEMS_SUCCESSFUL)
rtems_fatal_error_occurred (RTEMS_BLKDEV_FATAL_BDBUF_SO_WK_CREATE);
sc = rtems_task_start (worker->id,
rtems_bdbuf_swapout_worker_task,
(rtems_task_argument) worker);
if (sc != RTEMS_SUCCESSFUL)
rtems_fatal_error_occurred (RTEMS_BLKDEV_FATAL_BDBUF_SO_WK_START);
}
rtems_bdbuf_unlock_cache ();
}
/**
* Close the swapout worker threads.
*/
static void
rtems_bdbuf_swapout_workers_close (void)
{
rtems_chain_node* node;
rtems_bdbuf_lock_cache ();
node = rtems_chain_first (&bdbuf_cache.swapout_workers);
while (!rtems_chain_is_tail (&bdbuf_cache.swapout_workers, node))
{
rtems_bdbuf_swapout_worker* worker = (rtems_bdbuf_swapout_worker*) node;
worker->enabled = false;
rtems_event_send (worker->id, RTEMS_BDBUF_SWAPOUT_SYNC);
node = rtems_chain_next (node);
}
rtems_bdbuf_unlock_cache ();
}
/**
* Body of task which takes care on flushing modified buffers to the disk.
*
* @param arg A pointer to the global cache data. Use the global variable and
* not this.
* @return rtems_task Not used.
*/
static rtems_task
rtems_bdbuf_swapout_task (rtems_task_argument arg)
{
rtems_bdbuf_swapout_transfer transfer;
uint32_t period_in_ticks;
const uint32_t period_in_msecs = bdbuf_config.swapout_period;;
uint32_t timer_delta;
transfer.write_req = rtems_bdbuf_swapout_writereq_alloc ();
rtems_chain_initialize_empty (&transfer.bds);
transfer.dev = -1;
/*
* Localise the period.
*/
period_in_ticks = RTEMS_MICROSECONDS_TO_TICKS (period_in_msecs * 1000);
/*
* This is temporary. Needs to be changed to use the real time clock.
*/
timer_delta = period_in_msecs;
/*
* Create the worker threads.
*/
rtems_bdbuf_swapout_workers_open ();
while (bdbuf_cache.swapout_enabled)
{
rtems_event_set out;
rtems_status_code sc;
/*
* Only update the timers once in the processing cycle.
*/
bool update_timers = true;
/*
* If we write buffers to any disk perform a check again. We only write a
* single device at a time and the cache may have more than one device's
* buffers modified waiting to be written.
*/
bool transfered_buffers;
do
{
transfered_buffers = false;
/*
* Extact all the buffers we find for a specific device. The device is
* the first one we find on a modified list. Process the sync queue of
* buffers first.
*/
if (rtems_bdbuf_swapout_processing (timer_delta,
update_timers,
&transfer))
{
transfered_buffers = true;
}
/*
* Only update the timers once.
*/
update_timers = false;
}
while (transfered_buffers);
sc = rtems_event_receive (RTEMS_BDBUF_SWAPOUT_SYNC,
RTEMS_EVENT_ALL | RTEMS_WAIT,
period_in_ticks,
&out);
if ((sc != RTEMS_SUCCESSFUL) && (sc != RTEMS_TIMEOUT))
rtems_fatal_error_occurred (BLKDEV_FATAL_BDBUF_SWAPOUT_RE);
}
rtems_bdbuf_swapout_workers_close ();
free (transfer.write_req);
rtems_task_delete (RTEMS_SELF);
}
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