[PATCH 37/78] block: split block_class_lock

[Christoph Hellwig <hch@xxxxxx>]

Split the block_class_lock mutex into one each to protect bdev_map
and major_names.

Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Reviewed-by: Hannes Reinecke <hare@xxxxxxx>
---
 block/genhd.c | 29 +++++++++++++++--------------
 1 file changed, 15 insertions(+), 14 deletions(-)

diff --git a/block/genhd.c b/block/genhd.c
index 482f7b89802010..2a20372756625e 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -25,7 +25,6 @@
 
 #include "blk.h"
 
-static DEFINE_MUTEX(block_class_lock);
 static struct kobject *block_depr;
 
 struct bdev_map {
@@ -37,6 +36,7 @@ struct bdev_map {
        int (*lock)(dev_t, void *);
        void *data;
 } *bdev_map[255];
+static DEFINE_MUTEX(bdev_map_lock);
 
 /* for extended dynamic devt allocation, currently only one major is used */
 #define NR_EXT_DEVT            (1 << MINORBITS)
@@ -400,6 +400,7 @@ static struct blk_major_name {
        int major;
        char name[16];
 } *major_names[BLKDEV_MAJOR_HASH_SIZE];
+static DEFINE_MUTEX(major_names_lock);
 
 /* index in the above - for now: assume no multimajor ranges */
 static inline int major_to_index(unsigned major)
@@ -412,11 +413,11 @@ void blkdev_show(struct seq_file *seqf, off_t offset)
 {
        struct blk_major_name *dp;
 
-       mutex_lock(&block_class_lock);
+       mutex_lock(&major_names_lock);
        for (dp = major_names[major_to_index(offset)]; dp; dp = dp->next)
                if (dp->major == offset)
                        seq_printf(seqf, "%3d %s\n", dp->major, dp->name);
-       mutex_unlock(&block_class_lock);
+       mutex_unlock(&major_names_lock);
 }
 #endif /* CONFIG_PROC_FS */
 
@@ -445,7 +446,7 @@ int register_blkdev(unsigned int major, const char *name)
        struct blk_major_name **n, *p;
        int index, ret = 0;
 
-       mutex_lock(&block_class_lock);
+       mutex_lock(&major_names_lock);
 
        /* temporary */
        if (major == 0) {
@@ -498,7 +499,7 @@ int register_blkdev(unsigned int major, const char *name)
                kfree(p);
        }
 out:
-       mutex_unlock(&block_class_lock);
+       mutex_unlock(&major_names_lock);
        return ret;
 }
 
@@ -510,7 +511,7 @@ void unregister_blkdev(unsigned int major, const char *name)
        struct blk_major_name *p = NULL;
        int index = major_to_index(major);
 
-       mutex_lock(&block_class_lock);
+       mutex_lock(&major_names_lock);
        for (n = &major_names[index]; *n; n = &(*n)->next)
                if ((*n)->major == major)
                        break;
@@ -520,7 +521,7 @@ void unregister_blkdev(unsigned int major, const char *name)
                p = *n;
                *n = p->next;
        }
-       mutex_unlock(&block_class_lock);
+       mutex_unlock(&major_names_lock);
        kfree(p);
 }
 
@@ -671,7 +672,7 @@ void blk_register_region(dev_t devt, unsigned long range, 
struct module *module,
                p->data = data;
        }
 
-       mutex_lock(&block_class_lock);
+       mutex_lock(&bdev_map_lock);
        for (i = 0, p -= n; i < n; i++, p++, index++) {
                struct bdev_map **s = &bdev_map[index % 255];
                while (*s && (*s)->range < range)
@@ -679,7 +680,7 @@ void blk_register_region(dev_t devt, unsigned long range, 
struct module *module,
                p->next = *s;
                *s = p;
        }
-       mutex_unlock(&block_class_lock);
+       mutex_unlock(&bdev_map_lock);
 }
 EXPORT_SYMBOL(blk_register_region);
 
@@ -690,7 +691,7 @@ void blk_unregister_region(dev_t devt, unsigned long range)
        unsigned i;
        struct bdev_map *found = NULL;
 
-       mutex_lock(&block_class_lock);
+       mutex_lock(&bdev_map_lock);
        for (i = 0; i < min(n, 255u); i++, index++) {
                struct bdev_map **s;
                for (s = &bdev_map[index % 255]; *s; s = &(*s)->next) {
@@ -703,7 +704,7 @@ void blk_unregister_region(dev_t devt, unsigned long range)
                        }
                }
        }
-       mutex_unlock(&block_class_lock);
+       mutex_unlock(&bdev_map_lock);
        kfree(found);
 }
 EXPORT_SYMBOL(blk_unregister_region);
@@ -1034,7 +1035,7 @@ static struct gendisk *lookup_gendisk(dev_t dev, int 
*partno)
        unsigned long best = ~0UL;
 
 retry:
-       mutex_lock(&block_class_lock);
+       mutex_lock(&bdev_map_lock);
        for (p = bdev_map[MAJOR(dev) % 255]; p; p = p->next) {
                struct kobject *(*probe)(dev_t, int *, void *);
                struct module *owner;
@@ -1055,7 +1056,7 @@ static struct gendisk *lookup_gendisk(dev_t dev, int 
*partno)
                        module_put(owner);
                        continue;
                }
-               mutex_unlock(&block_class_lock);
+               mutex_unlock(&bdev_map_lock);
                kobj = probe(dev, partno, data);
                /* Currently ->owner protects _only_ ->probe() itself. */
                module_put(owner);
@@ -1063,7 +1064,7 @@ static struct gendisk *lookup_gendisk(dev_t dev, int 
*partno)
                        return dev_to_disk(kobj_to_dev(kobj));
                goto retry;
        }
-       mutex_unlock(&block_class_lock);
+       mutex_unlock(&bdev_map_lock);
        return NULL;
 }
 
-- 
2.29.2