loop: move loop_ctl_mutex locking into loop_add

Move acquiring and releasing loop_ctl_mutex from the callers into
loop_add.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Link: https://lore.kernel.org/r/20210623145908.92973-7-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index c3c6cfdcaf3476852d497015d80c33f404b32e84..c18e2930ca11fabc76e5ce052f6c2058df7d67ac 100644 (file)
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -2247,9 +2247,12 @@ static int loop_add(int i)
        lo = kzalloc(sizeof(*lo), GFP_KERNEL);
        if (!lo)
                goto out;
-
        lo->lo_state = Lo_unbound;
 
+       err = mutex_lock_killable(&loop_ctl_mutex);
+       if (err)
+               goto out_free_dev;
+
        /* allocate id, if @id >= 0, we're requesting that specific id */
        if (i >= 0) {
                err = idr_alloc(&loop_index_idr, lo, i, i + 1, GFP_KERNEL);
@@ -2259,7 +2262,7 @@ static int loop_add(int i)
                err = idr_alloc(&loop_index_idr, lo, 0, 0, GFP_KERNEL);
        }
        if (err < 0)
-               goto out_free_dev;
+               goto out_unlock;
        i = err;
 
        err = -ENOMEM;
@@ -2326,12 +2329,15 @@ static int loop_add(int i)
        disk->queue             = lo->lo_queue;
        sprintf(disk->disk_name, "loop%d", i);
        add_disk(disk);
-       return lo->lo_number;
+       mutex_unlock(&loop_ctl_mutex);
+       return i;
 
 out_cleanup_tags:
        blk_mq_free_tag_set(&lo->tag_set);
 out_free_idr:
        idr_remove(&loop_index_idr, i);
+out_unlock:
+       mutex_unlock(&loop_ctl_mutex);
 out_free_dev:
        kfree(lo);
 out:
@@ -2391,22 +2397,7 @@ static void loop_probe(dev_t dev)
 
        if (max_loop && idx >= max_loop)
                return;
-
-       mutex_lock(&loop_ctl_mutex);
        loop_add(idx);
-       mutex_unlock(&loop_ctl_mutex);
-}
-
-static int loop_control_add(int idx)
-{
-       int ret;
-               
-       ret = mutex_lock_killable(&loop_ctl_mutex);
-       if (ret)
-               return ret;
-       ret = loop_add(idx);
-       mutex_unlock(&loop_ctl_mutex);
-       return ret;
 }
 
 static int loop_control_remove(int idx)
@@ -2450,11 +2441,11 @@ static int loop_control_get_free(int idx)
        if (ret)
                return ret;
        ret = loop_lookup(&lo, -1);
-       if (ret < 0)
-               ret = loop_add(-1);
        mutex_unlock(&loop_ctl_mutex);
 
-       return ret;
+       if (ret >= 0)
+               return ret;
+       return loop_add(-1);
 }
 
 static long loop_control_ioctl(struct file *file, unsigned int cmd,
@@ -2462,7 +2453,7 @@ static long loop_control_ioctl(struct file *file, unsigned int cmd,
 {
        switch (cmd) {
        case LOOP_CTL_ADD:
-               return loop_control_add(parm);
+               return loop_add(parm);
        case LOOP_CTL_REMOVE:
                return loop_control_remove(parm);
        case LOOP_CTL_GET_FREE:
@@ -2543,10 +2534,8 @@ static int __init loop_init(void)
        }
 
        /* pre-create number of devices given by config or max_loop */
-       mutex_lock(&loop_ctl_mutex);
        for (i = 0; i < nr; i++)
                loop_add(i);
-       mutex_unlock(&loop_ctl_mutex);
 
        printk(KERN_INFO "loop: module loaded\n");
        return 0;