linux-kernel - [PATCH] drivers/block/zram/zram_drv.c: avoid needless checks in backing_dev

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Message-Id: <20200227081219.13144-1-zbestahu@gmail.com>
Date:   Thu, 27 Feb 2020 16:12:19 +0800
From:   Yue Hu <zbestahu@...il.com>
To:     minchan@...nel.org, ngupta@...are.org,
        sergey.senozhatsky.work@...il.com, axboe@...nel.dk
Cc:     linux-kernel@...r.kernel.org, huyue2@...ong.com, zbestahu@....com
Subject: [PATCH] drivers/block/zram/zram_drv.c: avoid needless checks in backing_dev_store() failure path

From: Yue Hu <huyue2@...ong.com>

There are null pointer checks in out block if backing_dev_store() fails.
That is needless, we can avoid them by setting different jumping label.

Signed-off-by: Yue Hu <huyue2@...ong.com>
---
 drivers/block/zram/zram_drv.c | 28 +++++++++++++---------------
 1 file changed, 13 insertions(+), 15 deletions(-)

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 61b10ab..a896f5c 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -465,7 +465,7 @@ static ssize_t backing_dev_store(struct device *dev,
 	if (init_done(zram)) {
 		pr_info("Can't setup backing device for initialized device\n");
 		err = -EBUSY;
-		goto out;
+		goto out_unlock;
 	}
 
 	strlcpy(file_name, buf, PATH_MAX);
@@ -478,7 +478,7 @@ static ssize_t backing_dev_store(struct device *dev,
 	if (IS_ERR(backing_dev)) {
 		err = PTR_ERR(backing_dev);
 		backing_dev = NULL;
-		goto out;
+		goto out_unlock;
 	}
 
 	mapping = backing_dev->f_mapping;
@@ -487,14 +487,14 @@ static ssize_t backing_dev_store(struct device *dev,
 	/* Support only block device in this moment */
 	if (!S_ISBLK(inode->i_mode)) {
 		err = -ENOTBLK;
-		goto out;
+		goto out_fclose;
 	}
 
 	bdev = bdgrab(I_BDEV(inode));
 	err = blkdev_get(bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL, zram);
 	if (err < 0) {
 		bdev = NULL;
-		goto out;
+		goto out_fclose;
 	}
 
 	nr_pages = i_size_read(inode) >> PAGE_SHIFT;
@@ -502,13 +502,13 @@ static ssize_t backing_dev_store(struct device *dev,
 	bitmap = kvzalloc(bitmap_sz, GFP_KERNEL);
 	if (!bitmap) {
 		err = -ENOMEM;
-		goto out;
+		goto out_blkdev_put;
 	}
 
 	old_block_size = block_size(bdev);
 	err = set_blocksize(bdev, PAGE_SIZE);
 	if (err)
-		goto out;
+		goto out_free_bitmap;
 
 	reset_bdev(zram);
 
@@ -535,16 +535,14 @@ static ssize_t backing_dev_store(struct device *dev,
 	kfree(file_name);
 
 	return len;
-out:
-	if (bitmap)
-		kvfree(bitmap);
-
-	if (bdev)
-		blkdev_put(bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL);
-
-	if (backing_dev)
-		filp_close(backing_dev, NULL);
 
+out_free_bitmap:
+	kvfree(bitmap);
+out_blkdev_put:
+	blkdev_put(bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL);
+out_fclose:
+	filp_close(backing_dev, NULL);
+out_unlock:
 	up_write(&zram->init_lock);
 
 	kfree(file_name);
-- 
1.9.1