xfstest has the following nicely written routine may be we can re-use that?
from git://git.kernel.org/pub/scm/fs/xfs/xfstests-dev.git, ${XFSTEST_HOME}/common/rc :-
2185 # check that kernel and filesystem support direct I/O
2186 _require_odirect()
2187 {
2188 if [ $FSTYP = "ext4" ] ; then
2189 if echo "$MOUNT_OPTIONS" | grep -q "test_dummy_encryption"; then
2190 _notrun "ext4 encryption doesn't support O_DIRECT"
2191 elif echo "$MOUNT_OPTIONS" | grep -q "data=journal"; then
2192 _notrun "ext4 data journaling doesn't support O_DIRECT"
2193 fi
2194 fi
2195 local testfile=$TEST_DIR/$$.direct
2196 $XFS_IO_PROG -F -f -d -c "pwrite 0 20k" $testfile > /dev/null 2>&1
2197 if [ $? -ne 0 ]; then
2198 _notrun "O_DIRECT is not supported"
2199 fi
2200 rm -f $testfile 2>&1 > /dev/null
2201 }
2202
This will require to have xfs_io program.
From: Johannes Thumshirn <jthumshirn@xxxxxxx>
Sent: Thursday, January 17, 2019 11:17 PM
To: Chaitanya Kulkarni; Omar Sandoval
Cc: Linux Block Layer Mailinglist; Linux NVMe Mailinglist; Anthony Iliopoulos
Subject: Re: [PATCH blktests 1/2] nvme: enable buffered_io for file-backed namespaces
On 18/01/2019 00:46, Chaitanya Kulkarni wrote:
> This will force the user to run all tests in the buffered_io mode.
>
> What we really need is a config for the nvme category option which user can set and decide
> whether to run buffered_io or direct_io, you can set by default to the buffered_io mode.
We could also introduce a check if we can use direct IO on the
underlying FS, but the only way I can think of from a shell script is
doing a 'dd of=$TMPDIR/testfile oflag=direct' and then populate the
result to the helper functions.
Chaitanya, Omar any ideas?
--
Johannes Thumshirn SUSE Labs Filesystems
jthumshirn@xxxxxxx +49 911 74053 689
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