btrfs-progs: Enhance btrfs-image to handle missing device

Can be fetched from github:
https://github.com/adam900710/btrfs-progs/tree/btrfs_image_fix

Bug report:
https://github.com/kdave/btrfs-progs/issues/118

In short, the problem is caused by some old code (read_extent_data() from ancient btrfs check code) and offset-by-one from btrfs-image. Which makes btrfs-image can only read from the first stripe of RAID1.

And if device of the first stripe is missing, btrfs-image will fail.

Fix the problem and add test case for it.

Qu Wenruo (3):
btrfs-progs: disk-io: Fix read_extent_data() error handler for missing
device
btrfs-progs: convert: Fix offset-by-one error in read_data_extent()
btrfs-progs: tests/misc: Test if btrfs-image can handle RAID1 missing
device

 disk-io.c                                         |  6 ++-
 image/main.c                                      |  2 +-
 tests/misc-tests/030-missing-device-image/test.sh | 57 +++++++++++++++++++++++
 3 files changed, 62 insertions(+), 3 deletions(-)
 create mode 100755 tests/misc-tests/030-missing-device-image/test.sh

2.16.3