[PATCH 5.4 38/77] btrfs: add info when mount fails due to stale replace target

[Greg Kroah-Hartman]

From: Anand Jain <anand.jain@xxxxxxxxxx>

commit f2c3bec215694fb8bc0ef5010f2a758d1906fc2d upstream.

If the replace target device reappears after the suspended replace is
cancelled, it blocks the mount operation as it can't find the matching
replace-item in the metadata. As shown below,

   BTRFS error (device sda5): replace devid present without an active replace item

To overcome this situation, the user can run the command

   btrfs device scan --forget <replace target device>

and try the mount command again. And also, to avoid repeating the issue,
superblock on the devid=0 must be wiped.

   wipefs -a device-path-to-devid=0.

This patch adds some info when this situation occurs.

Reported-by: Samuel Greiner <samuel@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/linux-btrfs/b4f62b10-b295-26ea-71f9-9a5c9299d42c@xxxxxxxxxxxxx/T/
CC: stable@xxxxxxxxxxxxxxx # 5.0+
Signed-off-by: Anand Jain <anand.jain@xxxxxxxxxx>
Signed-off-by: David Sterba <dsterba@xxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 fs/btrfs/dev-replace.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/fs/btrfs/dev-replace.c
+++ b/fs/btrfs/dev-replace.c
@@ -125,7 +125,7 @@ no_valid_dev_replace_entry_found:
 		if (btrfs_find_device(fs_info->fs_devices,
 				      BTRFS_DEV_REPLACE_DEVID, NULL, NULL, false)) {
 			btrfs_err(fs_info,
-			"replace devid present without an active replace item");
+"replace without active item, run 'device scan --forget' on the target device");
 			ret = -EUCLEAN;
 		} else {
 			dev_replace->srcdev = NULL;