GFS2 should support fiemap directly.
Created attachment 319557 [details] First guesstimated patch Based on the current proposed upstream patches. Not tested. Need to resolve locking order issue wrt the inode mutex. Currently this compiles, but is untested.
Created attachment 320301 [details] Latest version of patch As posted for review by the powers that be.
Created attachment 320303 [details] My version of Eric's test program I updated this from the version I found on the mailing lists so that it works with the latest FIEMAP impelmentation. Might need to copy some kernel headers to /usr/include/linux by hand as it looks like make headers_install doesn't do that.
This hit Linus' kernel today.