btrfs: merge btrfs_find_device and find_device

CVE-2019-18885

Both btrfs_find_device() and find_device() does the same thing except
that the latter does not take the seed device onto account in the device
scanning context. We can merge them.
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
(backported from commit 09ba3bc9)
[ Connor Kuehl: these functions still pass the root pointer as an
  argument instead of a `struct btrfs_fs_info *` so pass in the
  fs_devices object by accessing it through the root pointer. ]
Signed-off-by: Connor Kuehl <connor.kuehl@canonical.com>
Acked-by: Marcelo Henrique Cerri <marcelo.cerri@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

fs/btrfs/dev-replace.c

@@ -136,10 +136,10 @@ int btrfs_init_dev_replace(struct btrfs_fs_info *fs_info)
 	case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 	case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 		dev_replace->srcdev = btrfs_find_device(fs_info->fs_devices,
-							src_devid, NULL, NULL);
+						src_devid, NULL, NULL, true);
 		dev_replace->tgtdev = btrfs_find_device(fs_info->fs_devices,
 							BTRFS_DEV_REPLACE_DEVID,
-							NULL, NULL);
+							NULL, NULL, true);
 		/*
 		 * allow 'btrfs dev replace_cancel' if src/tgt device is
 		 * missing
@@ -647,8 +647,8 @@ static int btrfs_dev_replace_find_srcdev(struct btrfs_root *root, u64 srcdevid,
 
 	if (srcdevid) {
 		ret = 0;
-		*device = btrfs_find_device(root->fs_info, srcdevid, NULL,
-					    NULL);
+		*device = btrfs_find_device(root->fs_info->fs_devices, srcdevid,
+				NULL, NULL, false);
 		if (!*device)
 			ret = -ENOENT;
 	} else {

fs/btrfs/ioctl.c

@@ -1530,7 +1530,7 @@ static noinline int btrfs_ioctl_resize(struct file *file,
 		btrfs_info(root->fs_info, "resizing devid %llu", devid);
 	}
 
-	device = btrfs_find_device(root->fs_info->fs_devices, devid, NULL, NULL);
+	device = btrfs_find_device(root->fs_info->fs_devices, devid, NULL, NULL, true);
 	if (!device) {
 		btrfs_info(root->fs_info, "resizer unable to find device %llu",
 		       devid);
@@ -2772,7 +2772,8 @@ static long btrfs_ioctl_dev_info(struct btrfs_root *root, void __user *arg)
 		s_uuid = di_args->uuid;
 
 	mutex_lock(&fs_devices->device_list_mutex);
-	dev = btrfs_find_device(fs_devices, di_args->devid, s_uuid, NULL);
+	dev = btrfs_find_device(fs_devices, di_args->devid, s_uuid,
+				NULL, true);
 
 	if (!dev) {
 		ret = -ENODEV;

fs/btrfs/scrub.c

@@ -3836,7 +3836,7 @@ int btrfs_scrub_dev(struct btrfs_fs_info *fs_info, u64 devid, u64 start,
 
 
 	mutex_lock(&fs_info->fs_devices->device_list_mutex);
-	dev = btrfs_find_device(fs_info->fs_devices, devid, NULL, NULL);
+	dev = btrfs_find_device(fs_info->fs_devices, devid, NULL, NULL, true);
 	if (!dev || (dev->missing && !is_dev_replace)) {
 		mutex_unlock(&fs_info->fs_devices->device_list_mutex);
 		return -ENODEV;
@@ -4005,7 +4005,7 @@ int btrfs_scrub_progress(struct btrfs_root *root, u64 devid,
 	struct scrub_ctx *sctx = NULL;
 
 	mutex_lock(&root->fs_info->fs_devices->device_list_mutex);
-	dev = btrfs_find_device(root->fs_info->fs_devices, devid, NULL, NULL);
+	dev = btrfs_find_device(root->fs_info->fs_devices, devid, NULL, NULL, true);
 	if (dev)
 		sctx = dev->scrub_device;
 	if (sctx)

fs/btrfs/volumes.c

@@ -608,8 +608,8 @@ static noinline int device_list_add(const char *path,
 
 		device = NULL;
 	} else {
-		device = __find_device(&fs_devices->devices, devid,
-				       disk_super->dev_item.uuid);
+		device = btrfs_find_device(fs_devices, devid,
+				disk_super->dev_item.uuid, NULL, false);
 	}
 
 	if (!device) {
@@ -1779,7 +1779,7 @@ int btrfs_rm_device(struct btrfs_root *root, char *device_path)
 		devid = btrfs_stack_device_id(&disk_super->dev_item);
 		dev_uuid = disk_super->dev_item.uuid;
 		device = btrfs_find_device(root->fs_info->fs_devices, devid, dev_uuid,
-					   disk_super->fsid);
+					   disk_super->fsid, true);
 		if (!device) {
 			ret = -ENOENT;
 			goto error_brelse;
@@ -2063,7 +2063,7 @@ static int btrfs_find_device_by_path(struct btrfs_root *root, char *device_path,
 	devid = btrfs_stack_device_id(&disk_super->dev_item);
 	dev_uuid = disk_super->dev_item.uuid;
 	*device = btrfs_find_device(root->fs_info->fs_devices, devid, dev_uuid,
-			disk_super->fsid);
+			disk_super->fsid, true);
 	brelse(bh);
 	if (!*device)
 		ret = -ENOENT;
@@ -2219,9 +2219,9 @@ static int btrfs_finish_sprout(struct btrfs_trans_handle *trans,
 		read_extent_buffer(leaf, dev_uuid, btrfs_device_uuid(dev_item),
 				   BTRFS_UUID_SIZE);
 		read_extent_buffer(leaf, fs_uuid, btrfs_device_fsid(dev_item),
-				   BTRFS_UUID_SIZE);
+				   BTRFS_FSID_SIZE);
 		device = btrfs_find_device(root->fs_info->fs_devices, devid, dev_uuid,
-					   fs_uuid);
+					   fs_uuid, true);
 		BUG_ON(!device); /* Logic error */
 
 		if (device->fs_devices->seeding) {
@@ -6117,19 +6117,36 @@ int btrfs_map_bio(struct btrfs_root *root, int rw, struct bio *bio,
 	return 0;
 }
 
+/*
+ * Find a device specified by @devid or @uuid in the list of @fs_devices, or
+ * return NULL.
+ *
+ * If devid and uuid are both specified, the match must be exact, otherwise
+ * only devid is used.
+ *
+ * If @seed is true, traverse through the seed devices.
+ */
 struct btrfs_device *btrfs_find_device(struct btrfs_fs_devices *fs_devices,
-				       u64 devid, u8 *uuid, u8 *fsid)
+				       u64 devid, u8 *uuid, u8 *fsid,
+				       bool seed)
 {
 	struct btrfs_device *device;
 
 	while (fs_devices) {
 		if (!fsid ||
-		    !memcmp(fs_devices->fsid, fsid, BTRFS_UUID_SIZE)) {
-			device = __find_device(&fs_devices->devices, devid, uuid);
-			if (device)
+		    !memcmp(fs_devices->fsid, fsid, BTRFS_FSID_SIZE)) {
+			list_for_each_entry(device, &fs_devices->devices,
+					    dev_list) {
+				if (device->devid == devid &&
+				    (!uuid || memcmp(device->uuid, uuid,
+						     BTRFS_UUID_SIZE) == 0))
 					return device;
 			}
+		}
+		if (seed)
 			fs_devices = fs_devices->seed;
+		else
+			return NULL;
 	}
 	return NULL;
 }
@@ -6369,7 +6386,7 @@ static int read_one_chunk(struct btrfs_root *root, struct btrfs_key *key,
 				   btrfs_stripe_dev_uuid_nr(chunk, i),
 				   BTRFS_UUID_SIZE);
 		map->stripes[i].dev = btrfs_find_device(root->fs_info->fs_devices,
-							devid, uuid, NULL);
+							devid, uuid, NULL, true);
 		if (!map->stripes[i].dev && !btrfs_test_opt(root, DEGRADED)) {
 			free_extent_map(em);
 			return -EIO;
@@ -6498,7 +6515,7 @@ static int read_one_dev(struct btrfs_root *root,
 			return PTR_ERR(fs_devices);
 	}
 
-	device = btrfs_find_device(fs_devices, devid, dev_uuid, fs_uuid);
+	device = btrfs_find_device(fs_devices, devid, dev_uuid, fs_uuid, true);
 	if (!device) {
 		if (!btrfs_test_opt(root, DEGRADED))
 			return -EIO;
@@ -6961,7 +6978,7 @@ int btrfs_get_dev_stats(struct btrfs_root *root,
 	int i;
 
 	mutex_lock(&fs_devices->device_list_mutex);
-	dev = btrfs_find_device(fs_devices, stats->devid, NULL, NULL);
+	dev = btrfs_find_device(fs_devices, stats->devid, NULL, NULL, true);
 	mutex_unlock(&fs_devices->device_list_mutex);
 
 	if (!dev) {

fs/btrfs/volumes.h

@@ -463,7 +463,7 @@ int btrfs_num_copies(struct btrfs_fs_info *fs_info, u64 logical, u64 len);
 int btrfs_grow_device(struct btrfs_trans_handle *trans,
 		      struct btrfs_device *device, u64 new_size);
 struct btrfs_device *btrfs_find_device(struct btrfs_fs_devices *fs_devices,
-				       u64 devid, u8 *uuid, u8 *fsid);
+				       u64 devid, u8 *uuid, u8 *fsid, bool seed);
 int btrfs_shrink_device(struct btrfs_device *device, u64 new_size);
 int btrfs_init_new_device(struct btrfs_root *root, char *path);
 int btrfs_init_dev_replace_tgtdev(struct btrfs_root *root, char *device_path,