[fstests] hardcoded values in common/rc for xfs (and probably others)

[Anatoly Pugachev <matorola@gmail.com>]

Hello!

While running generic/012 on xfs filesystem created on sparc64 linux
(pagesize 8k) with "mkfs.xfs -b size=8192 /dev/vdiskb1" (but not with
the default mkfs.xfs which will use 4k block size) , I'm getting the
following output:

root@ttip:xfstests-dev# cat local.config
export TEST_DIR=/testvol
export TEST_DEV=/dev/vdiskb1
export SCRATCH_DEV_POOL="/dev/loop0 /dev/loop1 /dev/loop2"
export SCRATCH_MNT=/1/scratch
export MKFS_OPTIONS="-m reflink=1"

root@ttip:xfstests-dev# mkfs.xfs -b size=8192 -m reflink=1 -f /dev/vdiskb1
meta-data=/dev/vdiskb1           isize=512    agcount=4, agsize=983008 blks
         =                       sectsz=8192  attr=2, projid32bit=1
         =                       crc=1        finobt=1, sparse=0,
rmapbt=0, reflink=1
data     =                       bsize=8192   blocks=3932032, imaxpct=25
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=8192   ascii-ci=0 ftype=1
log      =internal log           bsize=8192   blocks=2160, version=2
         =                       sectsz=8192  sunit=1 blks, lazy-count=1
realtime =none                   extsz=8192   blocks=0, rtextents=0

root@ttip:xfstests-dev# ./check generic/012
FSTYP         -- xfs (debug)
PLATFORM      -- Linux/sparc64 ttip 4.14.0-rc5
MKFS_OPTIONS  -- -f -m reflink=1 /dev/loop0
MOUNT_OPTIONS -- /dev/loop0 /1/scratch

generic/012 2s ... [not run] xfs_io fcollapse failed (old kernel/wrong
fs/bad args?)
Not run: generic/012
Passed all 0 tests

root@ttip:xfstests-dev# xfs_io -V
xfs_io version 4.13.1


debugging it, comes from the following xfs_io command:

root@ttip:xfstests-dev# mount /dev/vdiskb1 /testvol/
root@ttip:xfstests-dev# /opt/xfsprogs/sbin/xfs_io -i -F -f -c "pwrite
0 20k" -c fsync -c "fcollapse 4k 8k" /testvol/248329.xfs_io 2>&1
wrote 20480/20480 bytes at offset 0
20 KiB, 3 ops; 0.0000 sec (95.741 MiB/sec and 14705.8824 ops/sec)
fallocate: Invalid argument


While chatting in #xfs irc channel, Darrick told that there is should
not be hardcoded values (like 4k for fcollapse) in generic/012, but it
comes from _require_xfs_io_command() from common/rc, quote:

19:19 < djwong> anyway... fcollapse (and finsert) both requires that
the offset/length arguments are block-aligned
19:19 < djwong> hence you can't fcollapse starting at 4k on an fs with 8k blocks

And it's not only generic/012, it fails generic/0{16,17,21,22} (and
probably more) as well.

Can someone look into this issue?
Thanks.