[PATCH 0/2] btrfs fiemap related BUG fix.

[robbieko <robbieko@synology.com>]

From: Robbie Ko <robbieko@synology.com>

This patchset intends to fix btrfs fiemap related bug.

The fiemap has the following problems:

1) Wrong extent count when fm_extent_count is zero.


2) SHARED bit is not correct
I have two ideas, but I do not know which one is the best.

Like:
 # dd if=/dev/zero bs=16K count=2 oflag=dsync of=/mnt/btrfs/file
 # xfs_io -c "fiemap -v" /mnt/btrfs/file
     /mnt/btrfs/file:
     EXT: FILE-OFFSET      BLOCK-RANGE      TOTAL FLAGS
       0: [0..63]:         4241424..4241487    64   0x1
 # cloner -s $((16*1024)) /mnt/btrfs/file /mnt/btrfs/file_clone

1. When any extent is shared in extent map, the entire extent map is shared
 # xfs_io -c "fiemap -v" /mnt/btrfs/file
     /mnt/btrfs/file:
     EXT: FILE-OFFSET      BLOCK-RANGE      TOTAL FLAGS
       0: [0..63]:         4241424..4241487   64  0x2001

2. Split into different extent
 # xfs_io -c "fiemap -v" /mnt/btrfs/file
     /mnt/btrfs/file:
     EXT: FILE-OFFSET      BLOCK-RANGE      TOTAL FLAGS
       0: [0..31]:         4241424..4241455   32  0x0
       1: [32..63]:        4241456..4241487   32  0x2001

Robbie Ko (2):
  Btrfs: fiemap: pass correct bytenr when fm_extent_count is zero
  Btrfs: fix fiemap extent SHARED flag error with range clone.

 fs/btrfs/extent_io.c | 150 ++++++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 132 insertions(+), 18 deletions(-)

--
1.9.1