block: don't take lock on changing ra_pages

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 Also remove out of date comment for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>

3 files changed, 1 insertions, 10 deletions

diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 21e275d7eed9..a29cb788e408 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -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);
diff --git a/block/compat_ioctl.c b/block/compat_ioctl.c
index 67eb93cff699..f87615dea46b 100644
--- a/block/compat_ioctl.c
+++ b/block/compat_ioctl.c
@@ -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;
diff --git a/block/ioctl.c b/block/ioctl.c
index d03985b04d67..0f22e629b13c 100644
--- a/block/ioctl.c
+++ b/block/ioctl.c
@@ -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 */