For many years, various btrfs users have written programs to discover the actual disk space used by files, using root-only interfaces. However, this information is a great fit for fiemap: it is inherently tied to extent information, all filesystems can use it, and the capabilities required for FIEMAP make sense for this additional information also. Hence, this patchset adds physical extent length information to fiemap, and extends btrfs to return it. This uses some of the reserved padding in the fiemap extent structure, so programs unaware of the new field will be unaffected by its presence. This is based on next-20240307. I've tested the btrfs part of this with the standard btrfs testing matrix locally, and verified that the physical extent information returned there is correct, but I'm still waiting on more tests. Please let me know what you think of the general idea! Sweet Tea Dorminy (3): fs: add physical_length field to fiemap extents fs: update fiemap_fill_next_extent() signature btrfs: fiemap: return extent physical size Documentation/filesystems/fiemap.rst | 29 +++++++++---- fs/bcachefs/fs.c | 6 ++- fs/btrfs/extent_io.c | 63 +++++++++++++++++----------- fs/ext4/extents.c | 1 + fs/f2fs/data.c | 8 ++-- fs/f2fs/inline.c | 3 +- fs/ioctl.c | 8 ++-- fs/iomap/fiemap.c | 2 +- fs/nilfs2/inode.c | 8 ++-- fs/ntfs3/frecord.c | 6 ++- fs/ocfs2/extent_map.c | 4 +- fs/smb/client/smb2ops.c | 1 + include/linux/fiemap.h | 2 +- include/uapi/linux/fiemap.h | 24 +++++++---- 14 files changed, 108 insertions(+), 57 deletions(-) base-commit: 1843e16d2df9d98427ef8045589571749d627cf7 -- 2.44.0
