[PATCH 03/18] block: split block_class_lock

Christoph Hellwig
2020-10-29T15:07:51Z

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

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

diff --git a/block/genhd.c b/block/genhd.c
index 0e22ca64aca09e..8be38725aad4e5 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;
}

--
2.28.0