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Diffstat (limited to 'cpukit/libblock/include/rtems/bdbuf.h')
| -rw-r--r-- | cpukit/libblock/include/rtems/bdbuf.h | 699 |
1 files changed, 0 insertions, 699 deletions
diff --git a/cpukit/libblock/include/rtems/bdbuf.h b/cpukit/libblock/include/rtems/bdbuf.h deleted file mode 100644 index edec05e099..0000000000 --- a/cpukit/libblock/include/rtems/bdbuf.h +++ /dev/null @@ -1,699 +0,0 @@ -/** - * @file - * - * @ingroup rtems_bdbuf - * @brief Block Device Buffer Management - */ - -/* - * Copyright (C) 2001 OKTET Ltd., St.-Petersburg, Russia - * Author: Victor V. Vengerov <vvv@oktet.ru> - * - * Copyright (C) 2008,2009 Chris Johns <chrisj@rtems.org> - * Rewritten to remove score mutex access. Fixes many performance - * issues. - * Change to support demand driven variable buffer sizes. - * - * Copyright (c) 2009-2012 embedded brains GmbH. - */ - -#ifndef _RTEMS_BDBUF_H -#define _RTEMS_BDBUF_H - -#include <rtems.h> -#include <rtems/libio.h> -#include <rtems/chain.h> - -#include <rtems/blkdev.h> -#include <rtems/diskdevs.h> - -#ifdef __cplusplus -extern "C" { -#endif - -/** - * @defgroup rtems_libblock Block Device Library - * - * Block device modules. - */ - -/** - * @defgroup rtems_bdbuf Block Device Buffer Management - * - * @ingroup rtems_libblock - * - * The Block Device Buffer Management implements a cache between the disk - * devices and file systems. The code provides read-ahead and write queuing to - * the drivers and fast cache look-up using an AVL tree. - * - * The block size used by a file system can be set at runtime and must be a - * multiple of the disk device block size. The disk device's physical block - * size is called the media block size. The file system can set the block size - * it uses to a larger multiple of the media block size. The driver must be - * able to handle buffers sizes larger than one media block. - * - * The user configures the amount of memory to be used as buffers in the cache, - * and the minimum and maximum buffer size. The cache will allocate additional - * memory for the buffer descriptors and groups. There are enough buffer - * descriptors allocated so all the buffer memory can be used as minimum sized - * buffers. - * - * The cache is a single pool of buffers. The buffer memory is divided into - * groups where the size of buffer memory allocated to a group is the maximum - * buffer size. A group's memory can be divided down into small buffer sizes - * that are a multiple of 2 of the minimum buffer size. A group is the minimum - * allocation unit for buffers of a specific size. If a buffer of maximum size - * is request the group will have a single buffer. If a buffer of minimum size - * is requested the group is divided into minimum sized buffers and the - * remaining buffers are held ready for use. A group keeps track of which - * buffers are with a file system or driver and groups who have buffer in use - * cannot be realloced. Groups with no buffers in use can be taken and - * realloced to a new size. This is how buffers of different sizes move around - * the cache. - - * The buffers are held in various lists in the cache. All buffers follow this - * state machine: - * - * @dot - * digraph state { - * size="16,8"; - * f [label="FREE",style="filled",fillcolor="aquamarine"]; - * e [label="EMPTY",style="filled",fillcolor="seagreen"]; - * c [label="CACHED",style="filled",fillcolor="chartreuse"]; - * ac [label="ACCESS CACHED",style="filled",fillcolor="royalblue"]; - * am [label="ACCESS MODIFIED",style="filled",fillcolor="royalblue"]; - * ae [label="ACCESS EMPTY",style="filled",fillcolor="royalblue"]; - * ap [label="ACCESS PURGED",style="filled",fillcolor="royalblue"]; - * t [label="TRANSFER",style="filled",fillcolor="red"]; - * tp [label="TRANSFER PURGED",style="filled",fillcolor="red"]; - * s [label="SYNC",style="filled",fillcolor="red"]; - * m [label="MODIFIED",style="filled",fillcolor="gold"]; - * i [label="INITIAL"]; - * - * legend_transfer [label="Transfer Wake-Up",fontcolor="red",shape="none"]; - * legend_access [label="Access Wake-Up",fontcolor="royalblue",shape="none"]; - * - * i -> f [label="Init"]; - * f -> e [label="Buffer Recycle"]; - * e -> ae [label="Get"]; - * e -> t [label="Read"]; - * e -> f [label="Nobody Waits"]; - * c -> ac [label="Get\nRead"]; - * c -> e [label="Buffer Recycle\nPurge"]; - * c -> f [label="Reallocate\nBlock Size Changed"]; - * t -> c [label="Transfer Done",color="red",fontcolor="red"]; - * t -> e [label="Transfer Error",color="red",fontcolor="red"]; - * t -> tp [label="Purge"]; - * tp -> e [label="Transfer Done\nTransfer Error",color="red",fontcolor="red"]; - * m -> t [label="Swapout"]; - * m -> s [label="Block Size Changed"]; - * m -> am [label="Get\nRead"]; - * m -> e [label="Purge"]; - * ac -> m [label="Release Modified",color="royalblue",fontcolor="royalblue"]; - * ac -> s [label="Sync",color="royalblue",fontcolor="royalblue"]; - * ac -> c [label="Release",color="royalblue",fontcolor="royalblue"]; - * ac -> ap [label="Purge"]; - * am -> m [label="Release\nRelease Modified",color="royalblue",fontcolor="royalblue"]; - * am -> s [label="Sync",color="royalblue",fontcolor="royalblue"]; - * am -> ap [label="Purge"]; - * ae -> m [label="Release Modified",color="royalblue",fontcolor="royalblue"]; - * ae -> s [label="Sync",color="royalblue",fontcolor="royalblue"]; - * ae -> e [label="Release",color="royalblue",fontcolor="royalblue"]; - * ae -> ap [label="Purge"]; - * ap -> e [label="Release\nRelease Modified\nSync",color="royalblue",fontcolor="royalblue"]; - * s -> t [label="Swapout"]; - * s -> e [label="Purge",color="red",fontcolor="red"]; - * } - * @enddot - * - * Empty or cached buffers are added to the LRU list and removed from this - * queue when a caller requests a buffer. This is referred to as getting a - * buffer in the code and the event get in the state diagram. The buffer is - * assigned to a block and inserted to the AVL based on the block/device key. - * If the block is to be read by the user and not in the cache it is transfered - * from the disk into memory. If no buffers are on the LRU list the modified - * list is checked. If buffers are on the modified the swap out task will be - * woken. The request blocks until a buffer is available for recycle. - * - * A block being accessed is given to the file system layer and not accessible - * to another requester until released back to the cache. The same goes to a - * buffer in the transfer state. The transfer state means being read or - * written. If the file system has modified the block and releases it as - * modified it placed on the cache's modified list and a hold timer - * initialised. The buffer is held for the hold time before being written to - * disk. Buffers are held for a configurable period of time on the modified - * list as a write sets the state to transfer and this locks the buffer out - * from the file system until the write completes. Buffers are often accessed - * and modified in a series of small updates so if sent to the disk when - * released as modified the user would have to block waiting until it had been - * written. This would be a performance problem. - * - * The code performs multiple block reads and writes. Multiple block reads or - * read-ahead increases performance with hardware that supports it. It also - * helps with a large cache as the disk head movement is reduced. It however - * is a speculative operation so excessive use can remove valuable and needed - * blocks from the cache. The read-ahead is triggered after two misses of - * ascending consecutive blocks or a read hit of a block read by the - * most-resent read-ahead transfer. The read-ahead works per disk, but all - * transfers are issued by the read-ahead task. - * - * The cache has the following lists of buffers: - * - LRU: Accessed or transfered buffers released in least recently used - * order. Empty buffers will be placed to the front. - * - Modified: Buffers waiting to be written to disk. - * - Sync: Buffers to be synchronized with the disk. - * - * A cache look-up will be performed to find a suitable buffer. A suitable - * buffer is one that matches the same allocation size as the device the buffer - * is for. The a buffer's group has no buffers in use with the file system or - * driver the group is reallocated. This means the buffers in the group are - * invalidated, resized and placed on the LRU queue. There is a performance - * issue with this design. The reallocation of a group may forced recently - * accessed buffers out of the cache when they should not. The design should be - * change to have groups on a LRU list if they have no buffers in use. - */ -/**@{**/ - -#if defined(RTEMS_POSIX_API) - /* - * Use the PTHREAD mutexes and condition variables if available. This helps - * on SMP configurations to avoid the home grown condition variables via - * disabled preemption. - */ - #define RTEMS_BDBUF_USE_PTHREAD -#endif - -/** - * @brief State of a buffer of the cache. - * - * The state has several implications. Depending on the state a buffer can be - * in the AVL tree, in a list, in use by an entity and a group user or not. - * - * <table> - * <tr> - * <th>State</th><th>Valid Data</th><th>AVL Tree</th> - * <th>LRU List</th><th>Modified List</th><th>Synchronization List</th> - * <th>Group User</th><th>External User</th> - * </tr> - * <tr> - * <td>FREE</td><td></td><td></td> - * <td>X</td><td></td><td></td><td></td><td></td> - * </tr> - * <tr> - * <td>EMPTY</td><td></td><td>X</td> - * <td></td><td></td><td></td><td></td><td></td> - * </tr> - * <tr> - * <td>CACHED</td><td>X</td><td>X</td> - * <td>X</td><td></td><td></td><td></td><td></td> - * </tr> - * <tr> - * <td>ACCESS CACHED</td><td>X</td><td>X</td> - * <td></td><td></td><td></td><td>X</td><td>X</td> - * </tr> - * <tr> - * <td>ACCESS MODIFIED</td><td>X</td><td>X</td> - * <td></td><td></td><td></td><td>X</td><td>X</td> - * </tr> - * <tr> - * <td>ACCESS EMPTY</td><td></td><td>X</td> - * <td></td><td></td><td></td><td>X</td><td>X</td> - * </tr> - * <tr> - * <td>ACCESS PURGED</td><td></td><td>X</td> - * <td></td><td></td><td></td><td>X</td><td>X</td> - * </tr> - * <tr> - * <td>MODIFIED</td><td>X</td><td>X</td> - * <td></td><td>X</td><td></td><td>X</td><td></td> - * </tr> - * <tr> - * <td>SYNC</td><td>X</td><td>X</td> - * <td></td><td></td><td>X</td><td>X</td><td></td> - * </tr> - * <tr> - * <td>TRANSFER</td><td>X</td><td>X</td> - * <td></td><td></td><td></td><td>X</td><td>X</td> - * </tr> - * <tr> - * <td>TRANSFER PURGED</td><td></td><td>X</td> - * <td></td><td></td><td></td><td>X</td><td>X</td> - * </tr> - * </table> - */ -typedef enum -{ - /** - * @brief Free. - */ - RTEMS_BDBUF_STATE_FREE = 0, - - /** - * @brief Empty. - */ - RTEMS_BDBUF_STATE_EMPTY, - - /** - * @brief Cached. - */ - RTEMS_BDBUF_STATE_CACHED, - - /** - * @brief Accessed by upper layer with cached data. - */ - RTEMS_BDBUF_STATE_ACCESS_CACHED, - - /** - * @brief Accessed by upper layer with modified data. - */ - RTEMS_BDBUF_STATE_ACCESS_MODIFIED, - - /** - * @brief Accessed by upper layer with invalid data. - */ - RTEMS_BDBUF_STATE_ACCESS_EMPTY, - - /** - * @brief Accessed by upper layer with purged data. - */ - RTEMS_BDBUF_STATE_ACCESS_PURGED, - - /** - * @brief Modified by upper layer. - */ - RTEMS_BDBUF_STATE_MODIFIED, - - /** - * @brief Scheduled for synchronization. - */ - RTEMS_BDBUF_STATE_SYNC, - - /** - * @brief In transfer by block device driver. - */ - RTEMS_BDBUF_STATE_TRANSFER, - - /** - * @brief In transfer by block device driver and purged. - */ - RTEMS_BDBUF_STATE_TRANSFER_PURGED -} rtems_bdbuf_buf_state; - -/** - * Forward reference to the block. - */ -struct rtems_bdbuf_group; -typedef struct rtems_bdbuf_group rtems_bdbuf_group; - -/** - * To manage buffers we using buffer descriptors (BD). A BD holds a buffer plus - * a range of other information related to managing the buffer in the cache. To - * speed-up buffer lookup descriptors are organized in AVL-Tree. The fields - * 'dd' and 'block' are search keys. - */ -typedef struct rtems_bdbuf_buffer -{ - rtems_chain_node link; /**< Link the BD onto a number of lists. */ - - struct rtems_bdbuf_avl_node - { - struct rtems_bdbuf_buffer* left; /**< Left Child */ - struct rtems_bdbuf_buffer* right; /**< Right Child */ - signed char cache; /**< Cache */ - signed char bal; /**< The balance of the sub-tree */ - } avl; - - rtems_disk_device *dd; /**< disk device */ - - rtems_blkdev_bnum block; /**< block number on the device */ - - unsigned char* buffer; /**< Pointer to the buffer memory area */ - - rtems_bdbuf_buf_state state; /**< State of the buffer. */ - - uint32_t waiters; /**< The number of threads waiting on this - * buffer. */ - rtems_bdbuf_group* group; /**< Pointer to the group of BDs this BD is - * part of. */ - uint32_t hold_timer; /**< Timer to indicate how long a buffer - * has been held in the cache modified. */ - - int references; /**< Allow reference counting by owner. */ - void* user; /**< User data. */ -} rtems_bdbuf_buffer; - -/** - * A group is a continuous block of buffer descriptors. A group covers the - * maximum configured buffer size and is the allocation size for the buffers to - * a specific buffer size. If you allocate a buffer to be a specific size, all - * buffers in the group, if there are more than 1 will also be that size. The - * number of buffers in a group is a multiple of 2, ie 1, 2, 4, 8, etc. - */ -struct rtems_bdbuf_group -{ - rtems_chain_node link; /**< Link the groups on a LRU list if they - * have no buffers in use. */ - size_t bds_per_group; /**< The number of BD allocated to this - * group. This value must be a multiple of - * 2. */ - uint32_t users; /**< How many users the block has. */ - rtems_bdbuf_buffer* bdbuf; /**< First BD this block covers. */ -}; - -/** - * Buffering configuration definition. See confdefs.h for support on using this - * structure. - */ -typedef struct rtems_bdbuf_config { - uint32_t max_read_ahead_blocks; /**< Number of blocks to read - * ahead. */ - uint32_t max_write_blocks; /**< Number of blocks to write - * at once. */ - rtems_task_priority swapout_priority; /**< Priority of the swap out - * task. */ - uint32_t swapout_period; /**< Period swap-out checks buf - * timers. */ - uint32_t swap_block_hold; /**< Period a buffer is held. */ - size_t swapout_workers; /**< The number of worker - * threads for the swap-out - * task. */ - rtems_task_priority swapout_worker_priority; /**< Priority of the swap out - * task. */ - size_t task_stack_size; /**< Task stack size for swap-out - * task and worker threads. */ - size_t size; /**< Size of memory in the - * cache */ - uint32_t buffer_min; /**< Minimum buffer size. */ - uint32_t buffer_max; /**< Maximum buffer size - * supported. It is also the - * allocation size. */ - rtems_task_priority read_ahead_priority; /**< Priority of the read-ahead - * task. */ -} rtems_bdbuf_config; - -/** - * External reference to the configuration. - * - * The configuration is provided by the application. - */ -extern const rtems_bdbuf_config rtems_bdbuf_configuration; - -/** - * The default value for the maximum read-ahead blocks disables the read-ahead - * feature. - */ -#define RTEMS_BDBUF_MAX_READ_AHEAD_BLOCKS_DEFAULT 0 - -/** - * Default maximum number of blocks to write at once. - */ -#define RTEMS_BDBUF_MAX_WRITE_BLOCKS_DEFAULT 16 - -/** - * Default swap-out task priority. - */ -#define RTEMS_BDBUF_SWAPOUT_TASK_PRIORITY_DEFAULT 15 - -/** - * Default swap-out task swap period in milli seconds. - */ -#define RTEMS_BDBUF_SWAPOUT_TASK_SWAP_PERIOD_DEFAULT 250 - -/** - * Default swap-out task block hold time in milli seconds. - */ -#define RTEMS_BDBUF_SWAPOUT_TASK_BLOCK_HOLD_DEFAULT 1000 - -/** - * Default swap-out worker tasks. Currently disabled. - */ -#define RTEMS_BDBUF_SWAPOUT_WORKER_TASKS_DEFAULT 0 - -/** - * Default swap-out worker task priority. The same as the swap-out task. - */ -#define RTEMS_BDBUF_SWAPOUT_WORKER_TASK_PRIORITY_DEFAULT \ - RTEMS_BDBUF_SWAPOUT_TASK_PRIORITY_DEFAULT - -/** - * Default read-ahead task priority. The same as the swap-out task. - */ -#define RTEMS_BDBUF_READ_AHEAD_TASK_PRIORITY_DEFAULT \ - RTEMS_BDBUF_SWAPOUT_TASK_PRIORITY_DEFAULT - -/** - * Default task stack size for swap-out and worker tasks. - */ -#define RTEMS_BDBUF_TASK_STACK_SIZE_DEFAULT RTEMS_MINIMUM_STACK_SIZE - -/** - * Default size of memory allocated to the cache. - */ -#define RTEMS_BDBUF_CACHE_MEMORY_SIZE_DEFAULT (64 * 512) - -/** - * Default minimum size of buffers. - */ -#define RTEMS_BDBUF_BUFFER_MIN_SIZE_DEFAULT (512) - -/** - * Default maximum size of buffers. - */ -#define RTEMS_BDBUF_BUFFER_MAX_SIZE_DEFAULT (4096) - -/** - * Prepare buffering layer to work - initialize buffer descritors and (if it is - * neccessary) buffers. After initialization all blocks is placed into the - * ready state. - * - * @retval RTEMS_SUCCESSFUL Successful operation. - * @retval RTEMS_CALLED_FROM_ISR Called from an interrupt context. - * @retval RTEMS_INVALID_NUMBER The buffer maximum is not an integral multiple - * of the buffer minimum. The maximum read-ahead blocks count is too large. - * @retval RTEMS_RESOURCE_IN_USE Already initialized. - * @retval RTEMS_UNSATISFIED Not enough resources. - */ -rtems_status_code -rtems_bdbuf_init (void); - -/** - * Get block buffer for data to be written into. The buffers is set to the - * access or modified access state. If the buffer is in the cache and modified - * the state is access modified else the state is access. This buffer contents - * are not initialised if the buffer is not already in the cache. If the block - * is already resident in memory it is returned how-ever if not in memory the - * buffer is not read from disk. This call is used when writing the whole block - * on a disk rather than just changing a part of it. If there is no buffers - * available this call will block. A buffer obtained with this call will not be - * involved in a transfer request and will not be returned to another user - * until released. If the buffer is already with a user when this call is made - * the call is blocked until the buffer is returned. The highest priority - * waiter will obtain the buffer first. - * - * The block number is the linear block number. This is relative to the start - * of the partition on the media. - * - * Before you can use this function, the rtems_bdbuf_init() routine must be - * called at least once to initialize the cache, otherwise a fatal error will - * occur. - * - * @param dd [in] The disk device. - * @param block [in] Linear media block number. - * @param bd [out] Reference to the buffer descriptor pointer. - * - * @retval RTEMS_SUCCESSFUL Successful operation. - * @retval RTEMS_INVALID_ID Invalid block number. - */ -rtems_status_code -rtems_bdbuf_get ( - rtems_disk_device *dd, - rtems_blkdev_bnum block, - rtems_bdbuf_buffer** bd -); - -/** - * Get the block buffer and if not already in the cache read from the disk. If - * specified block already cached return. The buffer is set to the access or - * modified access state. If the buffer is in the cache and modified the state - * is access modified else the state is access. If block is already being read - * from disk for being written to disk this call blocks. If the buffer is - * waiting to be written it is removed from modified queue and returned to the - * user. If the buffer is not in the cache a new buffer is obtained and the - * data read from disk. The call may block until these operations complete. A - * buffer obtained with this call will not be involved in a transfer request - * and will not be returned to another user until released. If the buffer is - * already with a user when this call is made the call is blocked until the - * buffer is returned. The highest priority waiter will obtain the buffer - * first. - * - * Before you can use this function, the rtems_bdbuf_init() routine must be - * called at least once to initialize the cache, otherwise a fatal error will - * occur. - * - * @param dd [in] The disk device. - * @param block [in] Linear media block number. - * @param bd [out] Reference to the buffer descriptor pointer. - * - * @retval RTEMS_SUCCESSFUL Successful operation. - * @retval RTEMS_INVALID_ID Invalid block number. - * @retval RTEMS_IO_ERROR IO error. - */ -rtems_status_code -rtems_bdbuf_read ( - rtems_disk_device *dd, - rtems_blkdev_bnum block, - rtems_bdbuf_buffer** bd -); - -/** - * Release the buffer obtained by a read call back to the cache. If the buffer - * was obtained by a get call and was not already in the cache the release - * modified call should be used. A buffer released with this call obtained by a - * get call may not be in sync with the contents on disk. If the buffer was in - * the cache and modified before this call it will be returned to the modified - * queue. The buffers is returned to the end of the LRU list. - * - * Before you can use this function, the rtems_bdbuf_init() routine must be - * called at least once to initialize the cache, otherwise a fatal error will - * occur. - * - * @param bd [in] Reference to the buffer descriptor. The buffer descriptor - * reference must not be @c NULL and must be obtained via rtems_bdbuf_get() or - * rtems_bdbuf_read(). - * - * @retval RTEMS_SUCCESSFUL Successful operation. - * @retval RTEMS_INVALID_ADDRESS The reference is NULL. - */ -rtems_status_code -rtems_bdbuf_release (rtems_bdbuf_buffer* bd); - -/** - * Release the buffer allocated with a get or read call placing it on the - * modified list. If the buffer was not released modified before the hold - * timer is set to the configuration value. If the buffer had been released - * modified before but not written to disk the hold timer is not updated. The - * buffer will be written to disk when the hold timer has expired, there are - * not more buffers available in the cache and a get or read buffer needs one - * or a sync call has been made. If the buffer is obtained with a get or read - * before the hold timer has expired the buffer will be returned to the user. - * - * Before you can use this function, the rtems_bdbuf_init() routine must be - * called at least once to initialize the cache, otherwise a fatal error will - * occur. - * - * @param bd [in] Reference to the buffer descriptor. The buffer descriptor - * reference must not be @c NULL and must be obtained via rtems_bdbuf_get() or - * rtems_bdbuf_read(). - * - * @retval RTEMS_SUCCESSFUL Successful operation. - * @retval RTEMS_INVALID_ADDRESS The reference is NULL. - */ -rtems_status_code -rtems_bdbuf_release_modified (rtems_bdbuf_buffer* bd); - -/** - * Release the buffer as modified and wait until it has been synchronized with - * the disk by writing it. This buffer will be the first to be transfer to disk - * and other buffers may also be written if the maximum number of blocks in a - * requests allows it. - * - * @note This code does not lock the sync mutex and stop additions to the - * modified queue. - * - * Before you can use this function, the rtems_bdbuf_init() routine must be - * called at least once to initialize the cache, otherwise a fatal error will - * occur. - * - * @param bd [in] Reference to the buffer descriptor. The buffer descriptor - * reference must not be @c NULL and must be obtained via rtems_bdbuf_get() or - * rtems_bdbuf_read(). - * - * @retval RTEMS_SUCCESSFUL Successful operation. - * @retval RTEMS_INVALID_ADDRESS The reference is NULL. - */ -rtems_status_code -rtems_bdbuf_sync (rtems_bdbuf_buffer* bd); - -/** - * Synchronize all modified buffers for this device with the disk and wait - * until the transfers have completed. The sync mutex for the cache is locked - * stopping the addition of any further modified buffers. It is only the - * currently modified buffers that are written. - * - * @note Nesting calls to sync multiple devices will be handled sequentially. A - * nested call will be blocked until the first sync request has complete. - * - * Before you can use this function, the rtems_bdbuf_init() routine must be - * called at least once to initialize the cache, otherwise a fatal error will - * occur. - * - * @param dd [in] The disk device. - * - * @retval RTEMS_SUCCESSFUL Successful operation. - */ -rtems_status_code -rtems_bdbuf_syncdev (rtems_disk_device *dd); - -/** - * @brief Purges all buffers corresponding to the disk device @a dd. - * - * This may result in loss of data. The read-ahead state of this device is reset. - * - * Before you can use this function, the rtems_bdbuf_init() routine must be - * called at least once to initialize the cache, otherwise a fatal error will - * occur. - * - * @param dd [in] The disk device. - */ -void -rtems_bdbuf_purge_dev (rtems_disk_device *dd); - -/** - * @brief Sets the block size of a disk device. - * - * This will set the block size derived fields of the disk device. If - * requested the disk device is synchronized before the block size change - * occurs. Since the cache is unlocked during the synchronization operation - * some tasks may access the disk device in the meantime. This may result in - * loss of data. After the synchronization the disk device is purged to ensure - * a consistent cache state and the block size change occurs. This also resets - * the read-ahead state of this disk device. Due to the purge operation this - * may result in loss of data. - * - * Before you can use this function, the rtems_bdbuf_init() routine must be - * called at least once to initialize the cache, otherwise a fatal error will - * occur. - * - * @param dd [in, out] The disk device. - * @param block_size [in] The new block size in bytes. - * @param sync [in] If @c true, then synchronize the disk device before the - * block size change. - * - * @retval RTEMS_SUCCESSFUL Successful operation. - * @retval RTEMS_INVALID_NUMBER Invalid block size. - */ -rtems_status_code -rtems_bdbuf_set_block_size (rtems_disk_device *dd, - uint32_t block_size, - bool sync); - -/** - * @brief Returns the block device statistics. - */ -void -rtems_bdbuf_get_device_stats (const rtems_disk_device *dd, - rtems_blkdev_stats *stats); - -/** - * @brief Resets the block device statistics. - */ -void -rtems_bdbuf_reset_device_stats (rtems_disk_device *dd); - -/** @} */ - -#ifdef __cplusplus -} -#endif - -#endif |