On 14/02/11 17:58, Marti Raudsepp wrote: > On Mon, Feb 14, 2011 at 17:01, Chris Mason <chris.ma...@oracle.com> wrote: >> Or, it could just be delalloc ;) > > I suspect delalloc. After creating the file, filefrag reports "1 > extent found", but for some reason it doesn't actually print out > details of the extent.
That's a bug in `filefrag -v` that I noticed independently yesterday. Without -v it will correctly report 0 extents. I've already suggested a patch to fix upstream. > After a "sync" call, the extent appears and "cp" starts working as expected: About that sync. I've noticed on ext4 loop back at least (and I suspect BTRFS is the same) that specifying FIEMAP_FLAG_SYNC (which cp does) is ineffective. I worked around this for cp tests by explicitly syncing with: dd if=/dev/null of=foo conv=notrunc,fdatasync > % rm -f foo bar > % echo foo > foo > % sync > % filefrag -v foo > Filesystem type is: 9123683e > File size of foo is 4 (1 block, blocksize 4096) > ext logical physical expected length flags > 0 0 0 4096 not_aligned,inline,eof > foo: 1 extent found > % cp foo bar > % hexdump bar > 0000000 6f66 0a6f > 0000004 OK that's fine for normal files. cp (from coreutils >= 8.10) may still do the wrong thing as it currently ignores FIEMAP_EXTENT_DATA_ENCRYPTED and FIEMAP_EXTENT_ENCODED as I've already reported: http://www.mail-archive.com/linux-btrfs@vger.kernel.org/msg08356.html I'd appreciate some `filefrag -v` output from a large compressed file. cheers, Pádraig. -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
