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Btrfs: send, fix issuing write op when processing hole in no data mode

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When doing an incremental send of a filesystem with the no-holes feature
enabled, we end up issuing a write operation when using the no data mode
send flag, instead of issuing an update extent operation. Fix this by
issuing the update extent operation instead.

Trivial reproducer:

  $ mkfs.btrfs -f -O no-holes /dev/sdc
  $ mkfs.btrfs -f /dev/sdd
  $ mount /dev/sdc /mnt/sdc
  $ mount /dev/sdd /mnt/sdd

  $ xfs_io -f -c "pwrite -S 0xab 0 32K" /mnt/sdc/foobar
  $ btrfs subvolume snapshot -r /mnt/sdc /mnt/sdc/snap1

  $ xfs_io -c "fpunch 8K 8K" /mnt/sdc/foobar
  $ btrfs subvolume snapshot -r /mnt/sdc /mnt/sdc/snap2

  $ btrfs send /mnt/sdc/snap1 | btrfs receive /mnt/sdd
  $ btrfs send --no-data -p /mnt/sdc/snap1 /mnt/sdc/snap2 \
       | btrfs receive -vv /mnt/sdd

Before this change the output of the second receive command is:

  receiving snapshot snap2 uuid=f6922049-8c22-e544-9ff9-fc6755918447...
  utimes
  write foobar, offset 8192, len 8192
  utimes foobar
  BTRFS_IOC_SET_RECEIVED_SUBVOL uuid=f6922049-8c22-e544-9ff9-...

After this change it is:

  receiving snapshot snap2 uuid=564d36a3-ebc8-7343-aec9-bf6fda278e64...
  utimes
  update_extent foobar: offset=8192, len=8192
  utimes foobar
  BTRFS_IOC_SET_RECEIVED_SUBVOL uuid=564d36a3-ebc8-7343-aec9-bf6fda278e64...

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Filipe Manana 2018-02-06 20:39:20 +00:00 committed by David Sterba
parent 3c181c12c4
commit d4dfc0f4d3
1 changed files with 3 additions and 0 deletions
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3
fs/btrfs/send.c
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@ -5005,6 +5005,9 @@ static int send_hole(struct send_ctx *sctx, u64 end)
u64 len;
int ret = 0;
if (sctx->flags & BTRFS_SEND_FLAG_NO_FILE_DATA)
return send_update_extent(sctx, offset, end - offset);
p = fs_path_alloc();
if (!p)
return -ENOMEM;