Hi all, This is a patchset implementing the GETFSMAP ioctl that we discussed at LSFMM 2016[1] and 2017. GETFSMAP takes two search keys, which are defined as a tuple of (device, physical block, owner, file offset), and returns all known space mapping information for the given filesystem. The XFS implementation is fully complete for filesystems having the new reverse-mapping feature introduced in 4.8. For legacy XFS filesystems and ext4, there is no reverse-mapping data and the returned extent information is restricted to listing "free", "unknown", or "metadata" owners. Space mapping information can be dumped via the xfs_io 'fsmap' command, and the upcoming xfs_spaceman/e2freefrag utilities analyze the free extent data to produce free space fragmentations reports. Further in the future, the xfs_scrub utility will use GETFSMAP to assist in data block read verification, and dedupe programs can use it to further optimize deduplication factors. Kernel source can be found in the git repo [2] and userspace utilities in the git repo[3]. This patchset is all ready to go for 4.12 -- the XFS patches have already been reviewed by Brian Foster; and the ext4 patch has been updated per some of Andreas Dilger's comments. This posting will (I hope) be the last one before 4.12. Test cases have already been integrated into xfstests, and the manpage will be the last patch. I'm particularly looking for acks & reviews of the VFS header, the ext4 patch, and the manpage. Patches 1, 9, and 10. Questions? Comments? --D [1] https://lwn.net/Articles/685978/ [2] https://git.kernel.org/cgit/linux/kernel/git/djwong/xfs-linux.git/log/?h=djwong-devel [3] https://git.kernel.org/cgit/linux/kernel/git/djwong/xfsprogs-dev.git/log/?h=djwong-devel
