linux-kernel - [PATCH linux-5.4.y 4/8] loop: Factor out setting loop device size

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Date: Thu,  7 Mar 2024 12:14:07 +0800
From: Genjian <zhanggenjian@....com>
To: stable@...r.kernel.org
Cc: axboe@...nel.dk,
	stable@...nel.org,
	linux-block@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	zhanggenjian123@...il.com,
	Martijn Coenen <maco@...roid.com>,
	Christoph Hellwig <hch@....de>,
	Genjian Zhang <zhanggenjian@...inos.cn>
Subject: [PATCH linux-5.4.y 4/8] loop: Factor out setting loop device size

From: Martijn Coenen <maco@...roid.com>

[ Upstream commit 5795b6f5607f7e4db62ddea144727780cb351a9b ]

This code is used repeatedly.

Signed-off-by: Martijn Coenen <maco@...roid.com>
Reviewed-by: Christoph Hellwig <hch@....de>
Signed-off-by: Jens Axboe <axboe@...nel.dk>
Signed-off-by: Genjian Zhang <zhanggenjian@...inos.cn>
---
 drivers/block/loop.c | 30 +++++++++++++++++++++---------
 1 file changed, 21 insertions(+), 9 deletions(-)

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 45237d44a867..78bfba4bce8a 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -226,20 +226,35 @@ static void __loop_update_dio(struct loop_device *lo, bool dio)
 	blk_mq_unfreeze_queue(lo->lo_queue);
 }
 
+/**
+ * loop_set_size() - sets device size and notifies userspace
+ * @lo: struct loop_device to set the size for
+ * @size: new size of the loop device
+ *
+ * Callers must validate that the size passed into this function fits into
+ * a sector_t, eg using loop_validate_size()
+ */
+static void loop_set_size(struct loop_device *lo, loff_t size)
+{
+	struct block_device *bdev = lo->lo_device;
+
+	set_capacity(lo->lo_disk, size);
+	bd_set_size(bdev, size << SECTOR_SHIFT);
+	/* let user-space know about the new size */
+	kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
+}
+
 static void
 figure_loop_size(struct loop_device *lo, loff_t offset, loff_t sizelimit)
 {
 	loff_t size = get_size(offset, sizelimit, lo->lo_backing_file);
-	struct block_device *bdev = lo->lo_device;
 
 	if (lo->lo_offset != offset)
 		lo->lo_offset = offset;
 	if (lo->lo_sizelimit != sizelimit)
 		lo->lo_sizelimit = sizelimit;
-	set_capacity(lo->lo_disk, size);
-	bd_set_size(bdev, (loff_t)get_capacity(bdev->bd_disk) << 9);
-	/* let user-space know about the new size */
-	kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
+
+	loop_set_size(lo, size);
 }
 
 static inline int
@@ -1033,11 +1048,8 @@ static int loop_set_fd(struct loop_device *lo, fmode_t mode,
 
 	loop_update_rotational(lo);
 	loop_update_dio(lo);
-	set_capacity(lo->lo_disk, size);
-	bd_set_size(bdev, size << 9);
 	loop_sysfs_init(lo);
-	/* let user-space know about the new size */
-	kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
+	loop_set_size(lo, size);
 
 	set_blocksize(bdev, S_ISBLK(inode->i_mode) ?
 		      block_size(inode->i_bdev) : PAGE_SIZE);
-- 
2.25.1