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Subject[PATCH 4.9 48/51] loop: Get rid of loop_index_mutex
Date
4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jan Kara <jack@suse.cz>

commit 0a42e99b58a208839626465af194cfe640ef9493 upstream.

Now that loop_ctl_mutex is global, just get rid of loop_index_mutex as
there is no good reason to keep these two separate and it just
complicates the locking.

Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/block/loop.c | 39 ++++++++++++++++++++-------------------
1 file changed, 20 insertions(+), 19 deletions(-)

--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -81,7 +81,6 @@
#include <asm/uaccess.h>

static DEFINE_IDR(loop_index_idr);
-static DEFINE_MUTEX(loop_index_mutex);
static DEFINE_MUTEX(loop_ctl_mutex);

static int max_part;
@@ -1560,9 +1559,11 @@ static int lo_compat_ioctl(struct block_
static int lo_open(struct block_device *bdev, fmode_t mode)
{
struct loop_device *lo;
- int err = 0;
+ int err;

- mutex_lock(&loop_index_mutex);
+ err = mutex_lock_killable(&loop_ctl_mutex);
+ if (err)
+ return err;
lo = bdev->bd_disk->private_data;
if (!lo) {
err = -ENXIO;
@@ -1571,7 +1572,7 @@ static int lo_open(struct block_device *

atomic_inc(&lo->lo_refcnt);
out:
- mutex_unlock(&loop_index_mutex);
+ mutex_unlock(&loop_ctl_mutex);
return err;
}

@@ -1580,12 +1581,11 @@ static void lo_release(struct gendisk *d
struct loop_device *lo;
int err;

- mutex_lock(&loop_index_mutex);
+ mutex_lock(&loop_ctl_mutex);
lo = disk->private_data;
if (atomic_dec_return(&lo->lo_refcnt))
- goto unlock_index;
+ goto out_unlock;

- mutex_lock(&loop_ctl_mutex);
if (lo->lo_flags & LO_FLAGS_AUTOCLEAR) {
/*
* In autoclear mode, stop the loop thread
@@ -1593,7 +1593,7 @@ static void lo_release(struct gendisk *d
*/
err = loop_clr_fd(lo);
if (!err)
- goto unlock_index;
+ return;
} else {
/*
* Otherwise keep thread (if running) and config,
@@ -1602,9 +1602,8 @@ static void lo_release(struct gendisk *d
loop_flush(lo);
}

+out_unlock:
mutex_unlock(&loop_ctl_mutex);
-unlock_index:
- mutex_unlock(&loop_index_mutex);
}

static const struct block_device_operations lo_fops = {
@@ -1890,7 +1889,7 @@ static struct kobject *loop_probe(dev_t
struct kobject *kobj;
int err;

- mutex_lock(&loop_index_mutex);
+ mutex_lock(&loop_ctl_mutex);
err = loop_lookup(&lo, MINOR(dev) >> part_shift);
if (err < 0)
err = loop_add(&lo, MINOR(dev) >> part_shift);
@@ -1898,7 +1897,7 @@ static struct kobject *loop_probe(dev_t
kobj = NULL;
else
kobj = get_disk(lo->lo_disk);
- mutex_unlock(&loop_index_mutex);
+ mutex_unlock(&loop_ctl_mutex);

*part = 0;
return kobj;
@@ -1908,9 +1907,13 @@ static long loop_control_ioctl(struct fi
unsigned long parm)
{
struct loop_device *lo;
- int ret = -ENOSYS;
+ int ret;
+
+ ret = mutex_lock_killable(&loop_ctl_mutex);
+ if (ret)
+ return ret;

- mutex_lock(&loop_index_mutex);
+ ret = -ENOSYS;
switch (cmd) {
case LOOP_CTL_ADD:
ret = loop_lookup(&lo, parm);
@@ -1924,7 +1927,6 @@ static long loop_control_ioctl(struct fi
ret = loop_lookup(&lo, parm);
if (ret < 0)
break;
- mutex_lock(&loop_ctl_mutex);
if (lo->lo_state != Lo_unbound) {
ret = -EBUSY;
mutex_unlock(&loop_ctl_mutex);
@@ -1936,7 +1938,6 @@ static long loop_control_ioctl(struct fi
break;
}
lo->lo_disk->private_data = NULL;
- mutex_unlock(&loop_ctl_mutex);
idr_remove(&loop_index_idr, lo->lo_number);
loop_remove(lo);
break;
@@ -1946,7 +1947,7 @@ static long loop_control_ioctl(struct fi
break;
ret = loop_add(&lo, -1);
}
- mutex_unlock(&loop_index_mutex);
+ mutex_unlock(&loop_ctl_mutex);

return ret;
}
@@ -2029,10 +2030,10 @@ static int __init loop_init(void)
THIS_MODULE, loop_probe, NULL, NULL);

/* pre-create number of devices given by config or max_loop */
- mutex_lock(&loop_index_mutex);
+ mutex_lock(&loop_ctl_mutex);
for (i = 0; i < nr; i++)
loop_add(&lo, i);
- mutex_unlock(&loop_index_mutex);
+ mutex_unlock(&loop_ctl_mutex);

printk(KERN_INFO "loop: module loaded\n");
return 0;

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