forked from Imagelibrary/rtems
595 lines
22 KiB
C
595 lines
22 KiB
C
/**
|
|
* @file
|
|
*
|
|
* @ingroup rtems_bdbuf
|
|
*
|
|
* 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 embedded brains GmbH.
|
|
*
|
|
* @(#) bdbuf.h,v 1.9 2005/02/02 00:06:18 joel Exp
|
|
*/
|
|
|
|
#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 modifed 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 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.
|
|
*
|
|
* @{
|
|
*/
|
|
|
|
/**
|
|
* @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
|
|
* 'dev' 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;
|
|
|
|
dev_t dev; /**< device number */
|
|
|
|
rtems_blkdev_bnum block; /**< block number on the device */
|
|
|
|
unsigned char* buffer; /**< Pointer to the buffer memory area */
|
|
|
|
volatile rtems_bdbuf_buf_state state; /**< State of the buffer. */
|
|
|
|
volatile 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. */
|
|
volatile 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 swapout checks buf
|
|
* timers. */
|
|
uint32_t swap_block_hold; /**< Period a buffer is held. */
|
|
size_t swapout_workers; /**< The number of worker
|
|
* threads for the swapout
|
|
* task. */
|
|
rtems_task_priority swapout_worker_priority; /**< Priority of the swap out
|
|
* task. */
|
|
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_bdbuf_config;
|
|
|
|
/**
|
|
* External reference to the configuration.
|
|
*
|
|
* The configuration is provided by the application.
|
|
*/
|
|
extern const rtems_bdbuf_config rtems_bdbuf_configuration;
|
|
|
|
/**
|
|
* The max_read_ahead_blocks value is altered if there are fewer buffers
|
|
* than this defined max. This stops thrashing in the cache.
|
|
*/
|
|
#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 swapout task.
|
|
*/
|
|
#define RTEMS_BDBUF_SWAPOUT_WORKER_TASK_PRIORITY_DEFAULT \
|
|
RTEMS_BDBUF_SWAPOUT_TASK_PRIORITY_DEFAULT
|
|
|
|
/**
|
|
* 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.
|
|
*
|
|
* @return RTEMS status code (RTEMS_SUCCESSFUL if operation completed
|
|
* successfully or error code if error is occured)
|
|
*/
|
|
rtems_status_code
|
|
rtems_bdbuf_init (void);
|
|
|
|
/**
|
|
* Get block buffer for data to be written into. The buffers is set to the
|
|
* access or modifed 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.
|
|
*
|
|
* @param device Device number (constructed of major and minor device number)
|
|
* @param block Linear media block number
|
|
* @param bd Reference to the buffer descriptor pointer.
|
|
*
|
|
* @return RTEMS status code (RTEMS_SUCCESSFUL if operation completed
|
|
* successfully or error code if error is occured)
|
|
*/
|
|
rtems_status_code
|
|
rtems_bdbuf_get (dev_t device, 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
|
|
* modifed 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.
|
|
*
|
|
* @param device Device number (constructed of major and minor device number)
|
|
* @param block Linear media block number
|
|
* @param bd Reference to the buffer descriptor pointer.
|
|
*
|
|
* @return RTEMS status code (RTEMS_SUCCESSFUL if operation completed
|
|
* successfully or error code if error is occured)
|
|
*/
|
|
rtems_status_code
|
|
rtems_bdbuf_read (dev_t device, 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.
|
|
*
|
|
* @param bd Reference to the buffer descriptor.
|
|
*
|
|
* @return RTEMS status code (RTEMS_SUCCESSFUL if operation completed
|
|
* successfully or error code if error is occured)
|
|
*/
|
|
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.
|
|
*
|
|
* @param bd Reference to the buffer descriptor.
|
|
*
|
|
* @return RTEMS status code (RTEMS_SUCCESSFUL if operation completed
|
|
* successfully or error code if error is occured)
|
|
*/
|
|
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.
|
|
|
|
* @param bd Reference to the buffer descriptor.
|
|
*
|
|
* @return RTEMS status code (RTEMS_SUCCESSFUL if operation completed
|
|
* successfully or error code if error is occured)
|
|
*/
|
|
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 modifed 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.
|
|
*
|
|
* @param dev Block device number
|
|
*
|
|
* @return RTEMS status code (RTEMS_SUCCESSFUL if operation completed
|
|
* successfully or error code if error is occured)
|
|
*/
|
|
rtems_status_code
|
|
rtems_bdbuf_syncdev (dev_t dev);
|
|
|
|
/**
|
|
* @brief Purges all buffers that matches the device identifier @a dev.
|
|
*
|
|
* This may result in loss of data.
|
|
*/
|
|
void
|
|
rtems_bdbuf_purge_dev (dev_t dev);
|
|
|
|
/**
|
|
* @brief Purges all buffers that matches the device major number @a major.
|
|
*
|
|
* This may result in loss of data.
|
|
*/
|
|
void
|
|
rtems_bdbuf_purge_major (rtems_device_major_number major);
|
|
|
|
/** @} */
|
|
|
|
#ifdef __cplusplus
|
|
}
|
|
#endif
|
|
|
|
#endif
|