At 09/05/2016 05:41 AM, Oliver Freyermuth wrote:
Am 30.08.2016 um 02:48 schrieb Qu Wenruo:
Yes.
And more specifically, it doesn't even affect delta backup.

For shared extents caused by reflink/dedupe(out-of-band or even incoming 
in-band), it will be send as individual files.

For contents, they are all the same, just more space usage.

For those interested, I have now actually tested the btrfs send / btrfs receive 
backup for several subvolumes after applying this patch.
The throughput is finally usable, almost hitting network / IO limits as 
expected - ideal so far!
Also delta seemed fine for the subvolumes for which things worked.

However, I now sadly get (for one of my subvolumes):

send ioctl failed with -2: No such file or directory

at some point during the transfer, it sadly seems to be reproducible.
I do not think it's related to this patch, but of course this makes "btrfs 
send" still unusable to me -
I guess it's not ready for general use just yet.
Is there any information I can easily extract / provide to allow the experts to 
fix this issue?

Did you get the half way send stream?

If the send stream has something, please use "--no-data" option to send the subvolume again to get the metadata only dump, and upload it for debug.

Also, please paste "btrfs-debug-tree -t <your subvolume id>" output for debug.
WARN: above "btrfs-debug-tree" command will contain file names.
You could use the following sed to wipe filename:

"btrfs-debug-tree  -t 5 /dev/sda6  | sed "s/name:.*//"

Thanks,
Qu

The kernel log shows nothing.

Thanks a lot,
        Oliver




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