glusterfs: discard (hole punch) support

Add support for the DISCARD file operation. Discard punches a hole
in a file in the provided range. Block de-allocation is implemented
via fallocate() (as requested via fuse and passed on to the brick
fs) but a separate fop is created within gluster to emphasize the
fact that discard changes file data (the discarded region is
replaced with zeroes) and must invalidate caches where appropriate.

BUG: 963678
Change-Id: I34633a0bfff2187afeab4292a15f3cc9adf261af
Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-on: http://review.gluster.org/5090
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Anand Avati <avati@redhat.com>

1 files changed, 56 insertions, 0 deletions

diff --git a/tests/bugs/bug-963678.t b/tests/bugs/bug-963678.t
new file mode 100644
index 000000000..14d566579
--- /dev/null
+++ b/tests/bugs/bug-963678.t
@@ -0,0 +1,56 @@
+#!/bin/bash
+#
+# Bug 963678 - Test discard functionality
+#
+# Test that basic discard (hole punch) functionality works via the fallocate
+# command line tool. Hole punch deallocates a region of a file, creating a hole
+# and a zero-filled data region. We verify that hole punch works, frees blocks
+# and that subsequent reads do not read stale data (caches are invalidated).
+#
+# NOTE: fuse fallocate is known to be broken with regard to cache invalidation
+# 	up to 3.9.0 kernels. Therefore, FOPEN_KEEP_CACHE is not used in this
+#	test (opens will invalidate the fuse cache).
+###
+
+. $(dirname $0)/../include.rc
+. $(dirname $0)/../fallocate.rc
+
+cleanup;
+
+TEST glusterd
+
+TEST $CLI volume create $V0 replica 2 $H0:$B0/${V0}{1,2}
+TEST $CLI volume start $V0
+
+TEST glusterfs --volfile-id=$V0 --volfile-server=$H0 $M0 --attribute-timeout=0 --entry-timeout=0
+
+# check for fallocate and hole punch support
+require_fallocate -l 1m $M0/file
+require_fallocate -p -l 512k $M0/file && rm -f $M0/file
+
+# allocate some blocks, punch a hole and verify block allocation
+TEST fallocate -l 1m $M0/file
+blksz=`stat --printf=%B $M0/file`
+nblks=`stat --printf=%b $M0/file`
+TEST [ $(($blksz * $nblks)) -ge 1048576 ]
+TEST fallocate -p -o 512k -l 128k $M0/file
+
+nblks=`stat --printf=%b $M0/file`
+# allow some room for xattr blocks
+TEST [ $(($blksz * $nblks)) -lt $((917504 + 16384)) ]
+TEST unlink $M0/file
+
+# write some data, punch a hole and verify the file content changes
+TEST dd if=/dev/urandom of=$M0/file bs=1M count=1
+TEST cp $M0/file $M0/file.copy.pre
+TEST fallocate -p -o 512k -l 128k $M0/file
+TEST cp $M0/file $M0/file.copy.post
+TEST ! cmp $M0/file.copy.pre $M0/file.copy.post
+TEST unlink $M0/file
+
+TEST umount $M0
+
+TEST $CLI volume stop $V0
+TEST $CLI volume delete $V0
+
+cleanup;