Because resuming from a token requires "guid" -> "snapshot" mapping
we have to walk the whole dataset hierarchy to find the right snapshot
to send; when both source and destination exists, for an incremental
resumable stream, libzfs gets confused and picks up the wrong snapshot
to send from: this results in attempting to send
"destination@snap1 -> source@snap2"
instead of
"source@snap1 -> source@snap2"
which fails with a "Invalid cross-device link" error (EXDEV).
Fix this by adjusting the logic behind dataset traversal in
zfs_iter_children() to pick the right snapshot to send from.
Additionally update dry-run 'zfs send -t' to print its output to
stderr: this is consistent with other dry-run commands.
Reviewed-by: George Melikov <mail@gmelikov.ru>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: loli10K <ezomori.nozomu@gmail.com>
Closes#6618Closes#6619Closes#6623
aee1dd4d98