[PATCH v7 0/4] btrfs-progs: image: new data dump feature

[Qu Wenruo <wqu@suse.com>]

This patchset includes the following features:

- Introduce data dump feature to dump the whole fs.
  This will introduce a new magic number to prevent old btrfs-image to
  hit failure as the item size limit is enlarged.
  Patch 1 and 2.

- Reduce memory usage for compressed data dump restore
  This is mostly due to the fact that we have much larger
  max_pending_size introduced by data dump(256K -> 256M).
  Using 4 * max_pending_size for each decompress thread as buffer is way
  too expensive now.
  Use proper inflate() to replace uncompress() calls.
  Patch 3

- A fix for small dev extent size mismatch with superblock
  This no longer affects single device dump restore, thus it's only
  for multi-device dump restore.
  Patch 4

Changelog:
v2:
- New small fixes:
  * Fix a confusing error message due to unpopulated errno
  * Output error message for chunk tree build error
  
- Fix a regression of previous version
  Patch "btrfs-progs: image: Rework how we search chunk tree blocks"
  deleted a "ret = 0" line which could cause false early exit.

- Reduce memory usage for data dump

v2.1:
- Rebased to devel branch
  Removing 4 already merged patches from the patchset.

- Re-order the patchset
  Put small and independent patches at the top of queue, and put the
  data dump related feature at the end.

- Fix -Wmaybe-uninitialized warnings
  Strangely, D=1 won't trigger these warnings thus they sneak into v2
  without being detected.

- Fix FROM: line
  Reverted to old smtp setup. The new setup will override FROM: line,
  messing up the name of author.

v3:
- Fix a wrong option in error string
- Fix a bug that we always dump data extents

v4:
- Rebased to latest devel branch
- Add a new small fix to kill the tiny dev extent size mismatch.

v5:
- Rebased to latest devel branch
- Checkpatch fixes

v6:
- Rebased to latest devel branch
  No conflicts at all.

v7:
- Rebased to latest devel branch
  No conflicts at all.

- Hide the data dump feature behind the experimental features
  Now to make "btrfs-image -d" work, one must enable experimental
  features, or "btrfs-image -d" will only output an error message.

  And if experimental features are not enabled, the new header format
  will also be disabled, so that btrfs-image can't detect the new format
  either.

  Although the "-d" option is still enabled for the non-experimental
  build.

  This only affects the 2nd patch, the remaining patches are not
  touched.

Qu Wenruo (4):
  btrfs-progs: image: introduce framework for more dump versions
  btrfs-progs: image: introduce -d option to dump data
  btrfs-progs: image: reduce memory requirement for decompression
  btrfs-progs: image: fix restored image size misalignment

 image/main.c     | 358 ++++++++++++++++++++++++++++++++++-------------
 image/metadump.h |  12 +-
 2 files changed, 273 insertions(+), 97 deletions(-)

-- 
2.32.0