[PATCH 4.4 30/65] Revert "loop: Get rid of loop_index_mutex"

Greg Kroah-Hartman
2019-02-04T10:40:44Z

From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

This reverts commit 611f77199cd763e6b7c0462c2f199ddb3a089750 which is
commit 0a42e99b58a208839626465af194cfe640ef9493 upstream.

It is not needed in the 4.4.y tree at this time.

Reported-by: Jan Kara <jack@suse.cz>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/block/loop.c | 39 +++++++++++++++++++--------------------
1 file changed, 19 insertions(+), 20 deletions(-)

--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -81,6 +81,7 @@
#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;
@@ -1570,11 +1571,9 @@ static int lo_compat_ioctl(struct block_
static int lo_open(struct block_device *bdev, fmode_t mode)
{
struct loop_device *lo;
- int err;
+ int err = 0;

- err = mutex_lock_killable(&loop_ctl_mutex);
- if (err)
- return err;
+ mutex_lock(&loop_index_mutex);
lo = bdev->bd_disk->private_data;
if (!lo) {
err = -ENXIO;
@@ -1583,7 +1582,7 @@ static int lo_open(struct block_device *

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

@@ -1592,11 +1591,12 @@ static void lo_release(struct gendisk *d
struct loop_device *lo;
int err;

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

+ mutex_lock(&loop_ctl_mutex);
if (lo->lo_flags & LO_FLAGS_AUTOCLEAR) {
/*
* In autoclear mode, stop the loop thread
@@ -1604,7 +1604,7 @@ static void lo_release(struct gendisk *d
*/
err = loop_clr_fd(lo);
if (!err)
- return;
+ goto unlock_index;
} else {
/*
* Otherwise keep thread (if running) and config,
@@ -1613,8 +1613,9 @@ 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 = {
@@ -1896,7 +1897,7 @@ static struct kobject *loop_probe(dev_t
struct kobject *kobj;
int err;

- mutex_lock(&loop_ctl_mutex);
+ mutex_lock(&loop_index_mutex);
err = loop_lookup(&lo, MINOR(dev) >> part_shift);
if (err < 0)
err = loop_add(&lo, MINOR(dev) >> part_shift);
@@ -1904,7 +1905,7 @@ static struct kobject *loop_probe(dev_t
kobj = NULL;
else
kobj = get_disk(lo->lo_disk);
- mutex_unlock(&loop_ctl_mutex);
+ mutex_unlock(&loop_index_mutex);

*part = 0;
return kobj;
@@ -1914,13 +1915,9 @@ static long loop_control_ioctl(struct fi
unsigned long parm)
{
struct loop_device *lo;
- int ret;
-
- ret = mutex_lock_killable(&loop_ctl_mutex);
- if (ret)
- return ret;
+ int ret = -ENOSYS;

- ret = -ENOSYS;
+ mutex_lock(&loop_index_mutex);
switch (cmd) {
case LOOP_CTL_ADD:
ret = loop_lookup(&lo, parm);
@@ -1934,6 +1931,7 @@ 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);
@@ -1945,6 +1943,7 @@ 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;
@@ -1954,7 +1953,7 @@ static long loop_control_ioctl(struct fi
break;
ret = loop_add(&lo, -1);
}
- mutex_unlock(&loop_ctl_mutex);
+ mutex_unlock(&loop_index_mutex);

return ret;
}
@@ -2037,10 +2036,10 @@ 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_ctl_mutex);
+ mutex_lock(&loop_index_mutex);
for (i = 0; i < nr; i++)
loop_add(&lo, i);
- mutex_unlock(&loop_ctl_mutex);
+ mutex_unlock(&loop_index_mutex);

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