queue-4.9/revert-loop-get-rid-of-loop_index_mutex.patch

   1 From 40be92f86e231126b4445ed185147004205c110c Mon Sep 17 00:00:00 2001
   2 From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
   3 Date: Wed, 27 Feb 2019 15:00:55 +0100
   4 Subject: Revert "loop: Get rid of loop_index_mutex"
   5
   6 From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
   7
   8 This reverts commit 6a8f1d8d701462937ce01a3f2219af5435372af7 which is
   9 commit 0a42e99b58a208839626465af194cfe640ef9493 upstream.
  10
  11 It does not work properly in the 4.9.y tree and causes more problems
  12 than it fixes, so revert it.
  13
  14 Reported-by: Thomas Lindroth <thomas.lindroth@gmail.com>
  15 Reported-by: Jan Kara <jack@suse.cz>
  16 Cc: Jens Axboe <axboe@kernel.dk>
  17 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  18 ---
  19  drivers/block/loop.c |   39 +++++++++++++++++++--------------------
  20  1 file changed, 19 insertions(+), 20 deletions(-)
  21
  22 --- a/drivers/block/loop.c
  23 +++ b/drivers/block/loop.c
  24 @@ -81,6 +81,7 @@
  25  #include <asm/uaccess.h>
  26
  27  static DEFINE_IDR(loop_index_idr);
  28 +static DEFINE_MUTEX(loop_index_mutex);
  29  static DEFINE_MUTEX(loop_ctl_mutex);
  30
  31  static int max_part;
  32 @@ -1559,11 +1560,9 @@ static int lo_compat_ioctl(struct block_
  33  static int lo_open(struct block_device *bdev, fmode_t mode)
  34  {
  35         struct loop_device *lo;
  36 -       int err;
  37 +       int err = 0;
  38
  39 -       err = mutex_lock_killable(&loop_ctl_mutex);
  40 -       if (err)
  41 -               return err;
  42 +       mutex_lock(&loop_index_mutex);
  43         lo = bdev->bd_disk->private_data;
  44         if (!lo) {
  45                 err = -ENXIO;
  46 @@ -1572,7 +1571,7 @@ static int lo_open(struct block_device *
  47
  48         atomic_inc(&lo->lo_refcnt);
  49  out:
  50 -       mutex_unlock(&loop_ctl_mutex);
  51 +       mutex_unlock(&loop_index_mutex);
  52         return err;
  53  }
  54
  55 @@ -1581,11 +1580,12 @@ static void lo_release(struct gendisk *d
  56         struct loop_device *lo;
  57         int err;
  58
  59 -       mutex_lock(&loop_ctl_mutex);
  60 +       mutex_lock(&loop_index_mutex);
  61         lo = disk->private_data;
  62         if (atomic_dec_return(&lo->lo_refcnt))
  63 -               goto out_unlock;
  64 +               goto unlock_index;
  65
  66 +       mutex_lock(&loop_ctl_mutex);
  67         if (lo->lo_flags & LO_FLAGS_AUTOCLEAR) {
  68                 /*
  69                  * In autoclear mode, stop the loop thread
  70 @@ -1593,7 +1593,7 @@ static void lo_release(struct gendisk *d
  71                  */
  72                 err = loop_clr_fd(lo);
  73                 if (!err)
  74 -                       return;
  75 +                       goto unlock_index;
  76         } else {
  77                 /*
  78                  * Otherwise keep thread (if running) and config,
  79 @@ -1602,8 +1602,9 @@ static void lo_release(struct gendisk *d
  80                 loop_flush(lo);
  81         }
  82
  83 -out_unlock:
  84         mutex_unlock(&loop_ctl_mutex);
  85 +unlock_index:
  86 +       mutex_unlock(&loop_index_mutex);
  87  }
  88
  89  static const struct block_device_operations lo_fops = {
  90 @@ -1889,7 +1890,7 @@ static struct kobject *loop_probe(dev_t
  91         struct kobject *kobj;
  92         int err;
  93
  94 -       mutex_lock(&loop_ctl_mutex);
  95 +       mutex_lock(&loop_index_mutex);
  96         err = loop_lookup(&lo, MINOR(dev) >> part_shift);
  97         if (err < 0)
  98                 err = loop_add(&lo, MINOR(dev) >> part_shift);
  99 @@ -1897,7 +1898,7 @@ static struct kobject *loop_probe(dev_t
 100                 kobj = NULL;
 101         else
 102                 kobj = get_disk(lo->lo_disk);
 103 -       mutex_unlock(&loop_ctl_mutex);
 104 +       mutex_unlock(&loop_index_mutex);
 105
 106         *part = 0;
 107         return kobj;
 108 @@ -1907,13 +1908,9 @@ static long loop_control_ioctl(struct fi
 109                                unsigned long parm)
 110  {
 111         struct loop_device *lo;
 112 -       int ret;
 113 -
 114 -       ret = mutex_lock_killable(&loop_ctl_mutex);
 115 -       if (ret)
 116 -               return ret;
 117 +       int ret = -ENOSYS;
 118
 119 -       ret = -ENOSYS;
 120 +       mutex_lock(&loop_index_mutex);
 121         switch (cmd) {
 122         case LOOP_CTL_ADD:
 123                 ret = loop_lookup(&lo, parm);
 124 @@ -1927,6 +1924,7 @@ static long loop_control_ioctl(struct fi
 125                 ret = loop_lookup(&lo, parm);
 126                 if (ret < 0)
 127                         break;
 128 +               mutex_lock(&loop_ctl_mutex);
 129                 if (lo->lo_state != Lo_unbound) {
 130                         ret = -EBUSY;
 131                         mutex_unlock(&loop_ctl_mutex);
 132 @@ -1938,6 +1936,7 @@ static long loop_control_ioctl(struct fi
 133                         break;
 134                 }
 135                 lo->lo_disk->private_data = NULL;
 136 +               mutex_unlock(&loop_ctl_mutex);
 137                 idr_remove(&loop_index_idr, lo->lo_number);
 138                 loop_remove(lo);
 139                 break;
 140 @@ -1947,7 +1946,7 @@ static long loop_control_ioctl(struct fi
 141                         break;
 142                 ret = loop_add(&lo, -1);
 143         }
 144 -       mutex_unlock(&loop_ctl_mutex);
 145 +       mutex_unlock(&loop_index_mutex);
 146
 147         return ret;
 148  }
 149 @@ -2030,10 +2029,10 @@ static int __init loop_init(void)
 150                                   THIS_MODULE, loop_probe, NULL, NULL);
 151
 152         /* pre-create number of devices given by config or max_loop */
 153 -       mutex_lock(&loop_ctl_mutex);
 154 +       mutex_lock(&loop_index_mutex);
 155         for (i = 0; i < nr; i++)
 156                 loop_add(&lo, i);
 157 -       mutex_unlock(&loop_ctl_mutex);
 158 +       mutex_unlock(&loop_index_mutex);
 159
 160         printk(KERN_INFO "loop: module loaded\n");
 161         return 0;