[PATCH RESEND v2 1/3] btrfs: drop never met condition of disk_total_bytes == 0

[Anand Jain <anand.jain@oracle.com>]

btrfs_device::disk_total_bytes is set even for a seed device (the
comment is wrong).

The function fill_device_from_item() does the job of reading it from the
item and updating btrfs_device::disk_total_bytes. So both the missing
device and the seed devices do have their disk_total_bytes updated.

Furthermore, while removing the device if there is a power loss, we could
have a device with its total_bytes = 0, that's still valid.

So this patch removes the check dev->disk_total_bytes == 0 in the
function verify_one_dev_extent(), which it does nothing in it.

And take this opportunity to introduce a check if the device::total_bytes
is more than the max device size in read_one_dev().

Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
---
v2: add check if the total_bytes is more than the actual device size in
    read_one_dev().
    update change log.

 fs/btrfs/volumes.c | 25 ++++++++++---------------
 1 file changed, 10 insertions(+), 15 deletions(-)

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index eb9ee7c2998f..e615ca393aab 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -6875,6 +6875,16 @@ static int read_one_dev(struct extent_buffer *leaf,
 	}
 
 	fill_device_from_item(leaf, dev_item, device);
+	if (device->bdev) {
+		u64 max_total_bytes = i_size_read(device->bdev->bd_inode);
+
+		if (device->total_bytes > max_total_bytes) {
+			btrfs_err(fs_info,
+			"device total_bytes should be below %llu but found %llu",
+				  max_total_bytes, device->total_bytes);
+			return -EINVAL;
+		}
+	}
 	set_bit(BTRFS_DEV_STATE_IN_FS_METADATA, &device->dev_state);
 	if (test_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state) &&
 	   !test_bit(BTRFS_DEV_STATE_REPLACE_TGT, &device->dev_state)) {
@@ -7608,21 +7618,6 @@ static int verify_one_dev_extent(struct btrfs_fs_info *fs_info,
 		goto out;
 	}
 
-	/* It's possible this device is a dummy for seed device */
-	if (dev->disk_total_bytes == 0) {
-		struct btrfs_fs_devices *devs;
-
-		devs = list_first_entry(&fs_info->fs_devices->seed_list,
-					struct btrfs_fs_devices, seed_list);
-		dev = btrfs_find_device(devs, devid, NULL, NULL, false);
-		if (!dev) {
-			btrfs_err(fs_info, "failed to find seed devid %llu",
-				  devid);
-			ret = -EUCLEAN;
-			goto out;
-		}
-	}
-
 	if (physical_offset + physical_len > dev->disk_total_bytes) {
 		btrfs_err(fs_info,
 "dev extent devid %llu physical offset %llu len %llu is beyond device boundary %llu",
-- 
2.25.1