From 8a12c4a456c7ee261a85c2cbec835601e6aae05a Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Fri, 8 May 2009 11:54:02 +0900 Subject: [PATCH] hd: dequeue and track in-flight request hd has at most single request in flight. Till now, whenever it needs to access the in-flight request it called elv_next_request(). This patch makes hd track the in-flight request directly and dequeue it when processing starts. The added complexity is minimal and this will help future block layer changes. [ Impact: dequeue in-flight request, one elv_next_request() per request ] Signed-off-by: Tejun Heo Signed-off-by: Jens Axboe --- drivers/block/hd.c | 63 +++++++++++++++++++++++++++++----------------- 1 file changed, 40 insertions(+), 23 deletions(-) diff --git a/drivers/block/hd.c b/drivers/block/hd.c index a3b39940ce0..288ab63c102 100644 --- a/drivers/block/hd.c +++ b/drivers/block/hd.c @@ -98,10 +98,9 @@ static DEFINE_SPINLOCK(hd_lock); static struct request_queue *hd_queue; +static struct request *hd_req; #define MAJOR_NR HD_MAJOR -#define QUEUE (hd_queue) -#define CURRENT elv_next_request(hd_queue) #define TIMEOUT_VALUE (6*HZ) #define HD_DELAY 0 @@ -195,11 +194,24 @@ static void __init hd_setup(char *str, int *ints) NR_HD = hdind+1; } +static bool hd_end_request(int err, unsigned int bytes) +{ + if (__blk_end_request(hd_req, err, bytes)) + return true; + hd_req = NULL; + return false; +} + +static bool hd_end_request_cur(int err) +{ + return hd_end_request(err, blk_rq_cur_bytes(hd_req)); +} + static void dump_status(const char *msg, unsigned int stat) { char *name = "hd?"; - if (CURRENT) - name = CURRENT->rq_disk->disk_name; + if (hd_req) + name = hd_req->rq_disk->disk_name; #ifdef VERBOSE_ERRORS printk("%s: %s: status=0x%02x { ", name, msg, stat & 0xff); @@ -227,8 +239,8 @@ static void dump_status(const char *msg, unsigned int stat) if (hd_error & (BBD_ERR|ECC_ERR|ID_ERR|MARK_ERR)) { printk(", CHS=%d/%d/%d", (inb(HD_HCYL)<<8) + inb(HD_LCYL), inb(HD_CURRENT) & 0xf, inb(HD_SECTOR)); - if (CURRENT) - printk(", sector=%ld", blk_rq_pos(CURRENT)); + if (hd_req) + printk(", sector=%ld", blk_rq_pos(hd_req)); } printk("\n"); } @@ -406,11 +418,12 @@ static void unexpected_hd_interrupt(void) */ static void bad_rw_intr(void) { - struct request *req = CURRENT; + struct request *req = hd_req; + if (req != NULL) { struct hd_i_struct *disk = req->rq_disk->private_data; if (++req->errors >= MAX_ERRORS || (hd_error & BBD_ERR)) { - __blk_end_request_cur(req, -EIO); + hd_end_request_cur(-EIO); disk->special_op = disk->recalibrate = 1; } else if (req->errors % RESET_FREQ == 0) reset = 1; @@ -454,14 +467,14 @@ static void read_intr(void) return; ok_to_read: - req = CURRENT; + req = hd_req; insw(HD_DATA, req->buffer, 256); #ifdef DEBUG printk("%s: read: sector %ld, remaining = %u, buffer=%p\n", req->rq_disk->disk_name, blk_rq_pos(req) + 1, blk_rq_sectors(req) - 1, req->buffer+512); #endif - if (__blk_end_request(req, 0, 512)) { + if (hd_end_request(0, 512)) { SET_HANDLER(&read_intr); return; } @@ -475,7 +488,7 @@ ok_to_read: static void write_intr(void) { - struct request *req = CURRENT; + struct request *req = hd_req; int i; int retries = 100000; @@ -494,7 +507,7 @@ static void write_intr(void) return; ok_to_write: - if (__blk_end_request(req, 0, 512)) { + if (hd_end_request(0, 512)) { SET_HANDLER(&write_intr); outsw(HD_DATA, req->buffer, 256); return; @@ -525,18 +538,18 @@ static void hd_times_out(unsigned long dummy) do_hd = NULL; - if (!CURRENT) + if (!hd_req) return; spin_lock_irq(hd_queue->queue_lock); reset = 1; - name = CURRENT->rq_disk->disk_name; + name = hd_req->rq_disk->disk_name; printk("%s: timeout\n", name); - if (++CURRENT->errors >= MAX_ERRORS) { + if (++hd_req->errors >= MAX_ERRORS) { #ifdef DEBUG printk("%s: too many errors\n", name); #endif - __blk_end_request_cur(CURRENT, -EIO); + hd_end_request_cur(-EIO); } hd_request(); spin_unlock_irq(hd_queue->queue_lock); @@ -551,7 +564,7 @@ static int do_special_op(struct hd_i_struct *disk, struct request *req) } if (disk->head > 16) { printk("%s: cannot handle device with more than 16 heads - giving up\n", req->rq_disk->disk_name); - __blk_end_request_cur(req, -EIO); + hd_end_request_cur(-EIO); } disk->special_op = 0; return 1; @@ -578,11 +591,15 @@ static void hd_request(void) repeat: del_timer(&device_timer); - req = CURRENT; - if (!req) { - do_hd = NULL; - return; + if (!hd_req) { + hd_req = elv_next_request(hd_queue); + if (!hd_req) { + do_hd = NULL; + return; + } + blkdev_dequeue_request(hd_req); } + req = hd_req; if (reset) { reset_hd(); @@ -595,7 +612,7 @@ repeat: ((block+nsect) > get_capacity(req->rq_disk))) { printk("%s: bad access: block=%d, count=%d\n", req->rq_disk->disk_name, block, nsect); - __blk_end_request_cur(req, -EIO); + hd_end_request_cur(-EIO); goto repeat; } @@ -635,7 +652,7 @@ repeat: break; default: printk("unknown hd-command\n"); - __blk_end_request_cur(req, -EIO); + hd_end_request_cur(-EIO); break; } } -- 2.20.1