linux-kernel - [PATCH v3 8/9] loop: Rework lo_ioctl() _

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Date:   Mon, 27 Apr 2020 09:42:21 +0200
From:   Martijn Coenen <maco@...roid.com>
To:     axboe@...nel.dk, hch@....de, ming.lei@...hat.com
Cc:     narayan@...gle.com, zezeozue@...gle.com, kernel-team@...roid.com,
        linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        maco@...gle.com, bvanassche@....org, Chaitanya.Kulkarni@....com,
        jaegeuk@...nel.org, Martijn Coenen <maco@...roid.com>
Subject: [PATCH v3 8/9] loop: Rework lo_ioctl() __user argument casting

In preparation for a new ioctl that needs to copy_from_user(); makes the
code easier to read as well.

Signed-off-by: Martijn Coenen <maco@...roid.com>
---
 drivers/block/loop.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index cd1efe0eec5a..92bbe368ab62 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -1660,6 +1660,7 @@ static int lo_ioctl(struct block_device *bdev, fmode_t mode,
 	unsigned int cmd, unsigned long arg)
 {
 	struct loop_device *lo = bdev->bd_disk->private_data;
+	void __user *argp = (void __user *) arg;
 	int err;
 
 	switch (cmd) {
@@ -1672,21 +1673,19 @@ static int lo_ioctl(struct block_device *bdev, fmode_t mode,
 	case LOOP_SET_STATUS:
 		err = -EPERM;
 		if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN)) {
-			err = loop_set_status_old(lo,
-					(struct loop_info __user *)arg);
+			err = loop_set_status_old(lo, argp);
 		}
 		break;
 	case LOOP_GET_STATUS:
-		return loop_get_status_old(lo, (struct loop_info __user *) arg);
+		return loop_get_status_old(lo, argp);
 	case LOOP_SET_STATUS64:
 		err = -EPERM;
 		if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN)) {
-			err = loop_set_status64(lo,
-					(struct loop_info64 __user *) arg);
+			err = loop_set_status64(lo, argp);
 		}
 		break;
 	case LOOP_GET_STATUS64:
-		return loop_get_status64(lo, (struct loop_info64 __user *) arg);
+		return loop_get_status64(lo, argp);
 	case LOOP_SET_CAPACITY:
 	case LOOP_SET_DIRECT_IO:
 	case LOOP_SET_BLOCK_SIZE:
-- 
2.26.2.303.gf8c07b1a785-goog