block: don't take lock on changing ra_pages
Wu Fengguang [Tue, 25 Nov 2008 08:08:39 +0000 (09:08 +0100)]
There's no need to take queue_lock or kernel_lock when modifying
bdi->ra_pages. So remove them. Also remove out of date comment for
queue_max_sectors_store().

Signed-off-by: Wu Fengguang <wfg@linux.intel.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

block/blk-sysfs.c
block/compat_ioctl.c
block/ioctl.c

index 21e275d..a29cb78 100644 (file)
@@ -88,9 +88,7 @@ queue_ra_store(struct request_queue *q, const char *page, size_t count)
        unsigned long ra_kb;
        ssize_t ret = queue_var_store(&ra_kb, page, count);
 
-       spin_lock_irq(q->queue_lock);
        q->backing_dev_info.ra_pages = ra_kb >> (PAGE_CACHE_SHIFT - 10);
-       spin_unlock_irq(q->queue_lock);
 
        return ret;
 }
@@ -117,10 +115,7 @@ queue_max_sectors_store(struct request_queue *q, const char *page, size_t count)
 
        if (max_sectors_kb > max_hw_sectors_kb || max_sectors_kb < page_kb)
                return -EINVAL;
-       /*
-        * Take the queue lock to update the readahead and max_sectors
-        * values synchronously:
-        */
+
        spin_lock_irq(q->queue_lock);
        q->max_sectors = max_sectors_kb << 1;
        spin_unlock_irq(q->queue_lock);
index 67eb93c..f87615d 100644 (file)
@@ -774,9 +774,7 @@ long compat_blkdev_ioctl(struct file *file, unsigned cmd, unsigned long arg)
                bdi = blk_get_backing_dev_info(bdev);
                if (bdi == NULL)
                        return -ENOTTY;
-               lock_kernel();
                bdi->ra_pages = (arg * 512) / PAGE_CACHE_SIZE;
-               unlock_kernel();
                return 0;
        case BLKGETSIZE:
                size = bdev->bd_inode->i_size;
index d03985b..0f22e62 100644 (file)
@@ -323,9 +323,7 @@ int blkdev_ioctl(struct block_device *bdev, fmode_t mode, unsigned cmd,
                bdi = blk_get_backing_dev_info(bdev);
                if (bdi == NULL)
                        return -ENOTTY;
-               lock_kernel();
                bdi->ra_pages = (arg * 512) / PAGE_CACHE_SIZE;
-               unlock_kernel();
                return 0;
        case BLKBSZSET:
                /* set the logical block size */