linux块设备缓冲机制，欢迎交流！！！
小弟最近在研究linux块设备缓冲机制，始终没有找齐相关的函数和数据结构，请大虾指导一下与块设备缓冲机制相关的源文件在哪里，具体有哪些文件，非常感谢！！！我只找到两个相关的数据结构
//linux-kernel2.2.0
//include/linux/fs.h
struct buffer_head {
/* First cache line: */
struct buffer_head * b_next; /* Hash queue list */
unsigned long b_blocknr; /* block number */
unsigned long b_size; /* block size */
kdev_t b_dev; /* device (B_FREE = free) */
kdev_t b_rdev; /* Real device */
unsigned long b_rsector; /* Real buffer location on disk */
struct buffer_head * b_this_page; /* circular list of buffers in one page */
unsigned long b_state; /* buffer state bitmap (see above) */
struct buffer_head * b_next_free;
unsigned int b_count; /* users using this block */
/* Non-performance-critical data follows. */
char * b_data; /* pointer to data block (1024 bytes) */
unsigned int b_list; /* List that this buffer appears */
unsigned long b_flushtime; /* Time when this (dirty) buffer
* should be written */
struct wait_queue * b_wait;
struct buffer_head ** b_pprev; /* doubly linked list of hash-queue */
struct buffer_head * b_prev_free; /* doubly linked list of buffers */
struct buffer_head * b_reqnext; /* request queue */
/*
* I/O completion
*/
void (*b_end_io)(struct buffer_head *bh, int uptodate);
void *b_dev_id;
};
//blkdev.h
struct request {
volatile int rq_status; /* should split this into a few status bits */
#define RQ_INACTIVE (-1)
#define RQ_ACTIVE 1
#define RQ_SCSI_BUSY 0xffff
#define RQ_SCSI_DONE 0xfffe
#define RQ_SCSI_DISCONNECTING 0xffe0
kdev_t rq_dev;
int cmd; /* READ or WRITE */
int errors;
unsigned long sector;
unsigned long nr_sectors;
unsigned long current_nr_sectors;
char * buffer;
struct semaphore * sem;
struct buffer_head * bh;
struct buffer_head * bhtail;
struct request * next;
}; ulk2 chapter 13, 14, 15
ldd2 block device driver chapter (i forget the number)
qjfx, chapter 5, 8
read them. and we can disuss here.
:-D:-D:-D I got it , Thanks welcome
good luck struct buffer_head * b_next; /* Hash queue list */
根据源代码，buffer_head可以处于３个queue中：
unused queue
request queue
hash queue
hash queue指的是什么呢，有什么作用？ pls read ULK2 14.2.1.3 The hash table of cached buffer heads
:-D
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