On Tue, Jan 23 2007, Jens Axboe wrote:
> On Sat, Jan 20 2007, FUJITA Tomonori wrote:
> > This enables bsg to resize the queue depth via
> > SG_SET_COMMAND_Q. bsg_command structures are allocated via mempool
> > because the previous way to use contiguous memory makes it difficult
> > to resize the queue depth when a bsg_device has outstanding commands.
>
> Overall the patch looks fine. I don't think we need a mempool though,
> and allocations could just use GFP_USER from the user invoked queuing
> paths. Just make it GFP_USER, we can always extend the
> bsg_alloc_command() to take a gfp_t argument as well If you get rid of
> the mempool, then resizing is simply just adjusting bd->max_queue.
Like so.
diff --git a/block/bsg.c b/block/bsg.c
index 9d77a0c..c56618a 100644
--- a/block/bsg.c
+++ b/block/bsg.c
@@ -33,8 +33,6 @@
static char bsg_version[] = "block layer sg (bsg) 0.4";
-struct bsg_command;
-
struct bsg_device {
struct gendisk *disk;
request_queue_t *queue;
@@ -46,8 +44,6 @@ struct bsg_device {
int minor;
int queued_cmds;
int done_cmds;
- unsigned long *cmd_bitmap;
- struct bsg_command *cmd_map;
wait_queue_head_t wq_done;
wait_queue_head_t wq_free;
char name[BDEVNAME_SIZE];
@@ -60,14 +56,7 @@ enum {
BSG_F_WRITE_PERM = 2,
};
-/*
- * command allocation bitmap defines
- */
-#define BSG_CMDS_PAGE_ORDER (1)
-#define BSG_CMDS_PER_LONG (sizeof(unsigned long) * 8)
-#define BSG_CMDS_MASK (BSG_CMDS_PER_LONG - 1)
-#define BSG_CMDS_BYTES (PAGE_SIZE * (1 << BSG_CMDS_PAGE_ORDER))
-#define BSG_CMDS (BSG_CMDS_BYTES / sizeof(struct bsg_command))
+#define BSG_DEFAULT_CMDS 64
#undef BSG_DEBUG
@@ -94,6 +83,8 @@ static struct hlist_head bsg_device_list[BSG_LIST_SIZE];
static struct class *bsg_class;
static LIST_HEAD(bsg_class_list);
+static struct kmem_cache *bsg_cmd_cachep;
+
/*
* our internal command type
*/
@@ -111,14 +102,12 @@ struct bsg_command {
static void bsg_free_command(struct bsg_command *bc)
{
struct bsg_device *bd = bc->bd;
- unsigned long bitnr = bc - bd->cmd_map;
unsigned long flags;
- dprintk("%s: command bit offset %lu\n", bd->name, bitnr);
+ kmem_cache_free(bsg_cmd_cachep, bc);
spin_lock_irqsave(&bd->lock, flags);
bd->queued_cmds--;
- __clear_bit(bitnr, bd->cmd_bitmap);
spin_unlock_irqrestore(&bd->lock, flags);
wake_up(&bd->wq_free);
@@ -127,32 +116,29 @@ static void bsg_free_command(struct bsg_command *bc)
static struct bsg_command *__bsg_alloc_command(struct bsg_device *bd)
{
struct bsg_command *bc = NULL;
- unsigned long *map;
- int free_nr;
spin_lock_irq(&bd->lock);
if (bd->queued_cmds >= bd->max_queue)
goto out;
- for (free_nr = 0, map = bd->cmd_bitmap; *map == ~0UL; map++)
- free_nr += BSG_CMDS_PER_LONG;
-
- BUG_ON(*map == ~0UL);
-
bd->queued_cmds++;
- free_nr += ffz(*map);
- __set_bit(free_nr, bd->cmd_bitmap);
spin_unlock_irq(&bd->lock);
- bc = bd->cmd_map + free_nr;
+ bc = kmem_cache_alloc(bsg_cmd_cachep, GFP_USER);
+ if (unlikely(!bc)) {
+ spin_lock_irq(&bd->lock);
+ goto alloc_fail;
+ }
+
memset(bc, 0, sizeof(*bc));
bc->bd = bd;
INIT_LIST_HEAD(&bc->list);
- dprintk("%s: returning free cmd %p (bit %d)\n", bd->name, bc, free_nr);
+ dprintk("%s: returning free cmd %p\n", bd->name, bc);
return bc;
+alloc_fail:
+ bd->queued_cmds--;
out:
- dprintk("%s: failed (depth %d)\n", bd->name, bd->queued_cmds);
spin_unlock_irq(&bd->lock);
return bc;
}
@@ -356,8 +342,8 @@ static void bsg_rq_end_io(struct request *rq, int uptodate)
struct bsg_device *bd = bc->bd;
unsigned long flags;
- dprintk("%s: finished rq %p bc %p, bio %p offset %Zd stat %d\n",
- bd->name, rq, bc, bc->bio, bc - bd->cmd_map, uptodate);
+ dprintk("%s: finished rq %p bc %p, bio %p stat %d\n",
+ bd->name, rq, bc, bc->bio, uptodate);
bc->hdr.duration = jiffies_to_msecs(jiffies - bc->hdr.duration);
@@ -703,21 +689,9 @@ bsg_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
return bytes_read;
}
-static void bsg_free_device(struct bsg_device *bd)
-{
- if (bd->cmd_map)
- free_pages((unsigned long) bd->cmd_map, BSG_CMDS_PAGE_ORDER);
-
- kfree(bd->cmd_bitmap);
- kfree(bd);
-}
-
static struct bsg_device *bsg_alloc_device(void)
{
- struct bsg_command *cmd_map;
- unsigned long *cmd_bitmap;
struct bsg_device *bd;
- int bits;
bd = kzalloc(sizeof(struct bsg_device), GFP_KERNEL);
if (unlikely(!bd))
@@ -725,19 +699,7 @@ static struct bsg_device *bsg_alloc_device(void)
spin_lock_init(&bd->lock);
- bd->max_queue = BSG_CMDS;
-
- bits = (BSG_CMDS / BSG_CMDS_PER_LONG) + 1;
- cmd_bitmap = kzalloc(bits * sizeof(unsigned long), GFP_KERNEL);
- if (!cmd_bitmap)
- goto out_free_bd;
- bd->cmd_bitmap = cmd_bitmap;
-
- cmd_map = (void *) __get_free_pages(GFP_KERNEL | __GFP_ZERO,
- BSG_CMDS_PAGE_ORDER);
- if (!cmd_map)
- goto out_free_bitmap;
- bd->cmd_map = cmd_map;
+ bd->max_queue = BSG_DEFAULT_CMDS;
INIT_LIST_HEAD(&bd->busy_list);
INIT_LIST_HEAD(&bd->done_list);
@@ -746,12 +708,6 @@ static struct bsg_device *bsg_alloc_device(void)
init_waitqueue_head(&bd->wq_free);
init_waitqueue_head(&bd->wq_done);
return bd;
-
-out_free_bitmap:
- kfree(cmd_bitmap);
-out_free_bd:
- kfree(bd);
- return NULL;
}
static int bsg_put_device(struct bsg_device *bd)
@@ -779,7 +735,7 @@ static int bsg_put_device(struct bsg_device *bd)
blk_put_queue(bd->queue);
hlist_del(&bd->dev_list);
- bsg_free_device(bd);
+ kfree(bd);
out:
mutex_unlock(&bsg_mutex);
return ret;
@@ -918,15 +874,17 @@ bsg_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
*/
case SG_GET_COMMAND_Q:
return put_user(bd->max_queue, uarg);
- case SG_SET_COMMAND_Q: {
+ case SG_SET_COMMAND_Q: {
int queue;
if (get_user(queue, uarg))
return -EFAULT;
- if (queue > BSG_CMDS || queue < 1)
+ if (queue < 1)
return -EINVAL;
+ spin_lock_irq(&bd->lock);
bd->max_queue = queue;
+ spin_unlock_irq(&bd->lock);
return 0;
}
@@ -1035,15 +993,25 @@ static int __init bsg_init(void)
{
int ret, i;
+ bsg_cmd_cachep = kmem_cache_create("bsg_cmd",
+ sizeof(struct bsg_command), 0, 0, NULL, NULL);
+ if (!bsg_cmd_cachep) {
+ printk(KERN_ERR "bsg: failed creating slab cache\n");
+ return -ENOMEM;
+ }
+
for (i = 0; i < BSG_LIST_SIZE; i++)
INIT_HLIST_HEAD(&bsg_device_list[i]);
bsg_class = class_create(THIS_MODULE, "bsg");
- if (IS_ERR(bsg_class))
+ if (IS_ERR(bsg_class)) {
+ kmem_cache_destroy(bsg_cmd_cachep);
return PTR_ERR(bsg_class);
+ }
ret = register_chrdev(BSG_MAJOR, "bsg", &bsg_fops);
if (ret) {
+ kmem_cache_destroy(bsg_cmd_cachep);
class_destroy(bsg_class);
return ret;
}
--
Jens Axboe
-
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