Quoting Chris Mason (2013-03-22 14:07:05) > [ mmap corruptions with leveldb and btrfs compression ] > > I ran this a number of times with compression off and wasn't able to > trigger problems. With compress=lzo, I see errors on every run. > > Compile: gcc -Wall -o mmap-trunc mmap-trunc.c > Run: ./mmap-trunc file_name > > The basic idea is to create a 256MB file in steps. Each step ftruncates > the file larger, and then mmaps a region for writing. It dirties some > unaligned bytes (a little more than 8K), and then munmaps. > > Then a verify stage goes back through the file to make sure the data we > wrote is really there. I'm using a simple rotating pattern of chars > that compress very well. Going through the code here, when I change the test to truncate once in the very beginning, I still get errors. So, it isn't an interaction between mmap and truncate. It must be a problem between lzo and mmap. -chris -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
