block: don't grab block_class_lock unnecessarily

block_class_lock protects major_names array and bdev_map and doesn't
have anything to do with block class devices.  Don't grab them while
iterating over block class devices.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

diff --git a/block/genhd.c b/block/genhd.c
index 0be95135c404396cce029209cb1e253d7fc1c7da..9eb8b3e212c1058988a6474439b4107e79b54f68 100644 (file)
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -283,9 +283,7 @@ static int printk_partition(struct device *dev, void *data)
  */
 void __init printk_all_partitions(void)
 {
-       mutex_lock(&block_class_lock);
        class_for_each_device(&block_class, NULL, NULL, printk_partition);
-       mutex_unlock(&block_class_lock);
 }
 
 #ifdef CONFIG_PROC_FS
@@ -305,17 +303,15 @@ static int find_start(struct device *dev, void *data)
 static void *part_start(struct seq_file *part, loff_t *pos)
 {
        struct device *dev;
-       loff_t k = *pos;
+       loff_t n = *pos;
 
-       if (!k)
+       if (!n)
                part->private = (void *)1LU;    /* tell show to print header */
 
-       mutex_lock(&block_class_lock);
-       dev = class_find_device(&block_class, NULL, &k, find_start);
-       if (dev) {
-               put_device(dev);
+       dev = class_find_device(&block_class, NULL, &n, find_start);
+       if (dev)
                return dev_to_disk(dev);
-       }
+
        return NULL;
 }
 
@@ -341,7 +337,6 @@ static void *part_next(struct seq_file *part, void *v, loff_t *pos)
 
 static void part_stop(struct seq_file *part, void *v)
 {
-       mutex_unlock(&block_class_lock);
 }
 
 static int show_partition(struct seq_file *part, void *v)
@@ -583,14 +578,12 @@ static struct device_type disk_type = {
 static void *diskstats_start(struct seq_file *part, loff_t *pos)
 {
        struct device *dev;
-       loff_t k = *pos;
+       loff_t n = *pos;
 
-       mutex_lock(&block_class_lock);
-       dev = class_find_device(&block_class, NULL, &k, find_start);
-       if (dev) {
-               put_device(dev);
+       dev = class_find_device(&block_class, NULL, &n, find_start);
+       if (dev)
                return dev_to_disk(dev);
-       }
+
        return NULL;
 }
 
@@ -610,7 +603,6 @@ static void *diskstats_next(struct seq_file *part, void *v, loff_t *pos)
 
 static void diskstats_stop(struct seq_file *part, void *v)
 {
-       mutex_unlock(&block_class_lock);
 }
 
 static int diskstats_show(struct seq_file *s, void *v)
@@ -729,7 +721,6 @@ dev_t blk_lookup_devt(const char *name, int part)
        dev_t devt = MKDEV(0, 0);
        struct find_block find;
 
-       mutex_lock(&block_class_lock);
        find.name = name;
        find.part = part;
        dev = class_find_device(&block_class, NULL, &find, match_id);
@@ -738,7 +729,6 @@ dev_t blk_lookup_devt(const char *name, int part)
                devt = MKDEV(MAJOR(dev->devt),
                             MINOR(dev->devt) + part);
        }
-       mutex_unlock(&block_class_lock);
 
        return devt;
 }