> On Wed, 07/20 09:09, Paolo Bonzini wrote: > > On 20/07/2016 06:37, Fam Zheng wrote: > > > Yes, you are right about this, I was confused because "qemu-img map" does > > > not > > > report this allocation state after zero write. (No idea why SEEK_DATA > > > doesn't > > > hit the fallocate'ed area.) > > > > Apparently it's because it's zeroed. > > > > $ fallocate -z -o 10485760 -l 10485760 test > > $ fallocate -p -o 49152000 -l 10485760 test > > $ fallocate -o 49152000 -l 10485760 test > > $ fallocate -p -o 65536000 -l 10485760 test > > > > Now we have: > > > > - a zero area at 10240K..20480K > > > > - an hole+allocated area at 48000K..59240K > > > > - a hole at 64000K..74240K > > > > $ qemu-img map test > > Offset Length Mapped to File > > 0 0xa00000 0 test << ends at 10240K > > 0x1400000 0x1ae0000 0x1400000 test << ends at 48000K > > 0x38e0000 0x5a0000 0x38e0000 test << ends at 64000K > > 0x4880000 0x1b80000 0x4880000 test > > Hah? I'm apparently missing something. I can't see these entries: > > > fam@ad:/var/tmp$ cat /tmp/sh > > touch test > > fallocate -z -o 10485760 -l 10485760 test > > fallocate -p -o 49152000 -l 10485760 test > > fallocate -o 49152000 -l 10485760 test > > fallocate -p -o 65536000 -l 10485760 test > > qemu-img map test > > fam@ad:/var/tmp$ sh /tmp/sh > > Offset Length Mapped to File > > (I'm using Fedora 24 but I've also tried RHEL 7.)
That was after a full allocation of a 1GB file. I didn't copy that line because I had the file lying around from another day--sorry. Paolo
