Hello! FS_IOC_FIEMAP on btrfs seems to be returning fe_physical values that don't always correspond to the actual on-disk data locations. For some files the values match, but e.g. for this file:
# filefrag -v foo Filesystem type is: 9123683e File size of foo is 4096 (1 block of 4096 bytes) ext: logical_offset: physical_offset: length: expected: flags: 0: 0.. 0: 5774454.. 5774454: 1: last,eof foo: 1 extent found # The file data is actually on disk not in block 5774454 (0x581c76), but in block 6038646 (0x5c2476), an offset of +0x40800. Is this expected behavior? Googling didn't turn up much, apologies if this is an FAQ. :( (This is on 4.18.16-200.fc28.x86_64, the current Fedora 28 kernel.) Thanks, Lennert
