Hi all, Here's an RFC patchset that partially implements the GETFSMAP ioctl on ext4. Because ext4 does not have reverse-mapping data, it uses the same fallback as XFS does when there's no rmapbt -- we report fixed-location metadata and the free extents listed in the block bitmaps, then fill in the rest with "owner unknown". Yes, this the same GETFSMAP ioctl that we discussed at LSFMM[1] that has been banging around in my XFS tree[2] for months. The second patch implements a semi-clone of the XFS FSGEOMETRY ioctl. The structure that ext4 returns is set up to mirror the XFS structure where there's overlap. The magic numbers of the ext4 ioctl are different to prevent old XFS tools from falling in by accident, though the intent is to ease adapting of the GETFSMAP xfs tools (xfs_io and xfs_spaceman) for ext4. My plan is to hoist the common GETFSMAP definitions (the structure, the flags, and none of the special owner codes) to the VFS prior to combining this patchset with its XFS counterpart. Note: The special owner codes (FMR_OWN_*) are filesystem specific and will never be hoisted to the VFS headers in their current form. However, I thought it might be useful to push this to the ext4 list for some early review. If you want to play with this, I recommend pulling my latest xfsprogs code from git[3] so that xfs_spaceman and xfs_io work on ext4. 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-wtf [3] https://git.kernel.org/cgit/linux/kernel/git/djwong/xfsprogs-dev.git/log/?h=djwong-wtf
