On Wed, Sep 23, 2020 at 05:37:39PM -0500, Eric Sandeen wrote: > Here's a reproducer for the bug. > > Requires sufficient privs to mount a loopback fs. Please turn this into an fstest case, but otherwise this looks reasonable. --D > > ====== > > #!/bin/bash > > mkdir -p mnt > umount mnt &>/dev/null > > # Create 8g fs image > mkfs.xfs -f -dfile,name=fsfile.img,size=8g &>/dev/null > mount -o loop fsfile.img mnt > > # Make all files w/ 1m hints; create original 2m file > xfs_io -c "extsize 1048576" mnt > xfs_io -c "cowextsize 1048576" mnt > > echo "Create file mnt/b" > xfs_io -f -c "pwrite -S 0x0 0 2m" -c fsync mnt/b &>/dev/null > > # Make a reflinked copy > echo "Reflink copy from mnt/b to mnt/a" > cp --reflink=always mnt/b mnt/a > > echo "Contents of mnt/b" > hexdump -C mnt/b > > # Cycle mount to get stuff out of cache > umount mnt > mount -o loop fsfile.img mnt > > # Create a 1m-hinted IO at offset 0, then > # do another IO that overlaps but extends past the 1m hint > echo "Write to mnt/a" > xfs_io -c "pwrite -S 0xa 0k -b 4k 4k" \ > -c "pwrite -S 0xa 4k -b 1m 1m" \ > mnt/a &>/dev/null > > xfs_io -c fsync mnt/a > > echo "Contents of mnt/b now:" > hexdump -C mnt/b > > umount mnt >
