This got picked up by xfstests generic/018 on a 2k block filesystem when it failed to defragment a file into 1 extent as expected. For some reason, the allocator is skipping over free blocks when it allocates the donor file. The attached image shows this behavior - if you do: # bunzip2 ext4.img.qcow.bz2 # qemu-img convert -O raw ext4.img.qcow ext4.img # mkdir -p mnt # mount -o loop ext4.img mnt/ # fallocate -l 20480 mnt/newfile # filefrag -v mnt/newfile Filesystem type is: ef53 File size of mnt/newfile is 20480 (10 blocks of 2048 bytes) ext: logical_offset: physical_offset: length: expected: flags: 0: 0.. 1: 16962.. 16963: 2: unwritten 1: 2.. 9: 16968.. 16975: 8: 16964: unwritten,eof mnt/newfile: 2 extents found it allocates 2 extents, even though the blocks in between the extents are free: # dumpe2fs test.img | grep -w 16964 dumpe2fs 1.42.9 (28-Dec-2013) Free blocks: 16964-16967, 16976-17407, 17410-17919, 17922-18431, 18434-18943, 18946-19455, 19457-19967, 19969-32767 I suppose this isn't critical, as defrag is best-effort and the allocator doesn't ever guarantee contiguous allocations, but it still seems a little odd so just thought I'd highlight it. Thanks, -Eric
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ext4.img.qcow.bz2
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