Revert "block: move the NEED_PART_SCAN flag to struct gendisk"

hulk inclusion
category: bugfix
bugzilla: 187190, https://gitee.com/src-openeuler/kernel/issues/I5GWOV
CVE: NA

--------------------------------

This reverts commit b2f0e44f.

Because it will introduce following problem in ltp zram tests:

BUG: unable to handle kernel NULL pointer dereference at 0000000000000600
PGD 0 P4D 0
Oops: 0002 [#1] SMP PTI
CPU: 28 PID: 172121 Comm: sh Kdump: loaded Tainted: G           OE    --------- -  - 4.18.0+ #2
Hardware name: Huawei RH2288H V3/BC11HGSA0, BIOS 5.15 05/21/2019
RIP: 0010:flush_disk+0x1d/0x50
RSP: 0018:ffffaf14a516fe20 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff899e26bac380 RCX: 0000000000000000
RDX: 0000000000000001 RSI: 0000000000000000 RDI: ffff899e26bac380
RBP: ffff899e26bac380 R08: 00000000000006a9 R09: 0000000000000004
R10: ffff89cd878ff440 R11: 0000000000000001 R12: 0000000000000000
R13: ffff899e26bac398 R14: ffffaf14a516ff00 R15: ffff89cd8709c3e0
FS:  00007f78d6840740(0000) GS:ffff89fcbf480000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000600 CR3: 000000308afc0002 CR4: 00000000001606e0
Call Trace:
 revalidate_disk+0x57/0x80
 reset_store+0xaf/0x120 [zram]
 kernfs_fop_write+0x10f/0x190
 vfs_write+0xad/0x1a0
 ksys_write+0x52/0xc0
 do_syscall_64+0x5d/0x1d0
 entry_SYSCALL_64_after_hwframe+0x65/0xca

This is because "bdev->bd_disk" is not ensured to exist, just convert
"set_bit(BDEV_NEED_PART_SCAN, &bdev->bd_flags)" to
"set_bit(GD_NEED_PART_SCAN, &bdev->bd_disk->state)" is wrong.

The reason to backport it is that commit 2a57456c8973 ("block:
Fix warning in bd_link_disk_holder()") has a regression that part scan
is disabled in device_add_disk(), and this problem will be fixed in
later patch.
Signed-off-by: NYu Kuai <yukuai3@huawei.com>
Reviewed-by: NJason Yan <yanaijie@huawei.com>
Signed-off-by: NYongqiang Liu <liuyongqiang13@huawei.com>

block/genhd.c

@@ -646,7 +646,7 @@ static void register_disk(struct device *parent, struct gendisk *disk)
 	if (!bdev)
 		goto exit;
 
-	set_bit(GD_NEED_PART_SCAN, &disk->state);
+	set_bit(BDEV_NEED_PART_SCAN, &bdev->bd_flags);
 	err = blkdev_get(bdev, FMODE_READ, NULL);
 	if (err < 0)
 		goto exit;

block/partition-generic.c

@@ -546,7 +546,7 @@ int rescan_partitions(struct gendisk *disk, struct block_device *bdev)
 	if (disk->fops->revalidate_disk)
 		disk->fops->revalidate_disk(disk);
 	check_disk_size_change(disk, bdev, true);
-	clear_bit(GD_NEED_PART_SCAN, &bdev->bd_disk->state);
+	clear_bit(BDEV_NEED_PART_SCAN, &bdev->bd_flags);
 	if (!get_capacity(disk) || !(state = check_partition(disk, bdev)))
 		return 0;
 	if (IS_ERR(state)) {
@@ -662,7 +662,7 @@ int invalidate_partitions(struct gendisk *disk, struct block_device *bdev)
 {
 	int res;
 
-	if (!test_bit(GD_NEED_PART_SCAN, &bdev->bd_disk->state))
+	if (!test_bit(BDEV_NEED_PART_SCAN, &bdev->bd_flags))
 		return 0;
 
 	res = drop_partitions(disk, bdev);
@@ -671,7 +671,7 @@ int invalidate_partitions(struct gendisk *disk, struct block_device *bdev)
 
 	set_capacity(disk, 0);
 	check_disk_size_change(disk, bdev, false);
-	clear_bit(GD_NEED_PART_SCAN, &bdev->bd_disk->state);
+	clear_bit(BDEV_NEED_PART_SCAN, &bdev->bd_flags);
 	/* tell userspace that the media / partition table may have changed */
 	kobject_uevent(&disk_to_dev(disk)->kobj, KOBJ_CHANGE);
 

drivers/block/nbd.c

@@ -317,7 +317,7 @@ static void nbd_size_update(struct nbd_device *nbd, bool start)
 			if (start)
 				set_blocksize(bdev, config->blksize);
 		} else
-			set_bit(GD_NEED_PART_SCAN, &nbd->disk->state);
+			set_bit(BDEV_NEED_PART_SCAN, &bdev->bd_flags);
 		bdput(bdev);
 	}
 	kobject_uevent(&nbd_to_dev(nbd)->kobj, KOBJ_CHANGE);
@@ -1343,7 +1343,7 @@ static int nbd_start_device_ioctl(struct nbd_device *nbd, struct block_device *b
 		return ret;
 
 	if (max_part)
-		set_bit(GD_NEED_PART_SCAN, &nbd->disk->state);
+		set_bit(BDEV_NEED_PART_SCAN, &bdev->bd_flags);
 	mutex_unlock(&nbd->config_lock);
 	ret = wait_event_interruptible(config->recv_wq,
 					 atomic_read(&config->recv_threads) == 0);
@@ -1524,9 +1524,9 @@ static int nbd_open(struct block_device *bdev, fmode_t mode)
 		refcount_set(&nbd->config_refs, 1);
 		refcount_inc(&nbd->refs);
 		mutex_unlock(&nbd->config_lock);
-		set_bit(GD_NEED_PART_SCAN, &bdev->bd_disk->state);
+		set_bit(BDEV_NEED_PART_SCAN, &bdev->bd_flags);
 	} else if (nbd_disconnected(nbd->config)) {
-		set_bit(GD_NEED_PART_SCAN, &bdev->bd_disk->state);
+		set_bit(BDEV_NEED_PART_SCAN, &bdev->bd_flags);
 	}
 out:
 	mutex_unlock(&nbd_index_mutex);

fs/block_dev.c

@@ -922,6 +922,7 @@ struct block_device *bdget(dev_t dev)
 		bdev->bd_inode = inode;
 		bdev->bd_block_size = i_blocksize(inode);
 		bdev->bd_part_count = 0;
+		bdev->bd_flags = 0;
 		inode->i_mode = S_IFBLK;
 		inode->i_rdev = dev;
 		inode->i_bdev = bdev;
@@ -1403,7 +1404,7 @@ static void flush_disk(struct block_device *bdev, bool kill_dirty)
 		       "resized disk %s\n",
 		       bdev->bd_disk ? bdev->bd_disk->disk_name : "");
 	}
-	set_bit(GD_NEED_PART_SCAN, &bdev->bd_disk->state);
+	set_bit(BDEV_NEED_PART_SCAN, &bdev->bd_flags);
 }
 
 /**
@@ -1456,7 +1457,7 @@ int revalidate_disk(struct gendisk *disk)
 
 	mutex_lock(&bdev->bd_mutex);
 	check_disk_size_change(disk, bdev, ret == 0);
-	clear_bit(GD_NEED_PART_SCAN, &disk->state);
+	clear_bit(BDEV_NEED_PART_SCAN, &bdev->bd_flags);
 	mutex_unlock(&bdev->bd_mutex);
 	bdput(bdev);
 	return ret;
@@ -1519,7 +1520,7 @@ static void bdev_disk_changed(struct block_device *bdev, bool invalidate)
 		up_read(&disk->lookup_sem);
 	} else {
 		check_disk_size_change(bdev->bd_disk, bdev, !invalidate);
-		clear_bit(GD_NEED_PART_SCAN, &bdev->bd_disk->state);
+		clear_bit(BDEV_NEED_PART_SCAN, &bdev->bd_flags);
 	}
 }
 
@@ -1604,7 +1605,7 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
 			 * The latter is necessary to prevent ghost
 			 * partitions on a removed medium.
 			 */
-			if (test_bit(GD_NEED_PART_SCAN, &disk->state) &&
+			if (test_bit(BDEV_NEED_PART_SCAN, &bdev->bd_flags) &&
 			    (!ret || ret == -ENOMEDIUM))
 				bdev_disk_changed(bdev, ret == -ENOMEDIUM);
 
@@ -1641,7 +1642,7 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
 			if (bdev->bd_disk->fops->open)
 				ret = bdev->bd_disk->fops->open(bdev, mode);
 			/* the same as first opener case, read comment there */
-			if (test_bit(GD_NEED_PART_SCAN, &disk->state) &&
+			if (test_bit(BDEV_NEED_PART_SCAN, &bdev->bd_flags) &&
 			    (!ret || ret == -ENOMEDIUM))
 				bdev_disk_changed(bdev, ret == -ENOMEDIUM);
 			if (ret)

include/linux/fs.h

@@ -459,6 +459,8 @@ struct address_space {
 	 */
 struct request_queue;
 
+#define BDEV_NEED_PART_SCAN            0
+
 struct block_device {
 	dev_t			bd_dev;  /* not a kdev_t - it's a search key */
 	int			bd_openers;
@@ -479,6 +481,7 @@ struct block_device {
 	struct hd_struct *	bd_part;
 	/* number of times partitions within this device have been opened. */
 	unsigned		bd_part_count;
+	unsigned long		bd_flags;
 	struct gendisk *	bd_disk;
 	struct request_queue *  bd_queue;
 	struct backing_dev_info *bd_bdi;

include/linux/genhd.h

@@ -208,8 +208,6 @@ struct gendisk {
 	void *private_data;
 
 	int flags;
-	unsigned long state;
-#define GD_NEED_PART_SCAN		0
 	struct rw_semaphore lookup_sem;
 	struct kobject *slave_dir;