Add support for DISCARD to ZVOLs.

DISCARD (REQ_DISCARD, BLKDISCARD) is useful for thin provisioning.
It allows ZVOL clients to discard (unmap, trim) block ranges from
a ZVOL, thus optimizing disk space usage by allowing a ZVOL to
shrink instead of just grow.

We can't use zfs_space() or zfs_freesp() here, since these functions
only work on regular files, not volumes. Fortunately we can use the
low-level function dmu_free_long_range() which does exactly what we
want.

Currently the discard operation is not added to the log. That's not
a big deal since losing discard requests cannot result in data
corruption. It would however result in disk space usage higher than
it should be. Thus adding log support to zvol_discard() is probably
a good idea for a future improvement.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>

Makefile.in

@@ -72,6 +72,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
 	$(top_srcdir)/config/kernel-blk-end-request.m4 \
 	$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
+	$(top_srcdir)/config/kernel-blk-queue-discard.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-flush.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-io-opt.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-max-hw-sectors.m4 \

cmd/Makefile.in

@@ -49,6 +49,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
 	$(top_srcdir)/config/kernel-blk-end-request.m4 \
 	$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
+	$(top_srcdir)/config/kernel-blk-queue-discard.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-flush.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-io-opt.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-max-hw-sectors.m4 \

cmd/mount_zfs/Makefile.in

@@ -52,6 +52,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
 	$(top_srcdir)/config/kernel-blk-end-request.m4 \
 	$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
+	$(top_srcdir)/config/kernel-blk-queue-discard.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-flush.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-io-opt.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-max-hw-sectors.m4 \

cmd/sas_switch_id/Makefile.in

@@ -51,6 +51,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
 	$(top_srcdir)/config/kernel-blk-end-request.m4 \
 	$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
+	$(top_srcdir)/config/kernel-blk-queue-discard.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-flush.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-io-opt.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-max-hw-sectors.m4 \

cmd/zdb/Makefile.in

@@ -52,6 +52,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
 	$(top_srcdir)/config/kernel-blk-end-request.m4 \
 	$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
+	$(top_srcdir)/config/kernel-blk-queue-discard.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-flush.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-io-opt.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-max-hw-sectors.m4 \

cmd/zfs/Makefile.in

@@ -52,6 +52,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
 	$(top_srcdir)/config/kernel-blk-end-request.m4 \
 	$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
+	$(top_srcdir)/config/kernel-blk-queue-discard.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-flush.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-io-opt.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-max-hw-sectors.m4 \

cmd/zinject/Makefile.in

@@ -52,6 +52,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
 	$(top_srcdir)/config/kernel-blk-end-request.m4 \
 	$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
+	$(top_srcdir)/config/kernel-blk-queue-discard.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-flush.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-io-opt.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-max-hw-sectors.m4 \

cmd/zpios/Makefile.in

@@ -52,6 +52,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
 	$(top_srcdir)/config/kernel-blk-end-request.m4 \
 	$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
+	$(top_srcdir)/config/kernel-blk-queue-discard.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-flush.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-io-opt.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-max-hw-sectors.m4 \

cmd/zpool/Makefile.in

@@ -52,6 +52,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
 	$(top_srcdir)/config/kernel-blk-end-request.m4 \
 	$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
+	$(top_srcdir)/config/kernel-blk-queue-discard.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-flush.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-io-opt.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-max-hw-sectors.m4 \

cmd/zpool_id/Makefile.in

@@ -51,6 +51,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
 	$(top_srcdir)/config/kernel-blk-end-request.m4 \
 	$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
+	$(top_srcdir)/config/kernel-blk-queue-discard.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-flush.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-io-opt.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-max-hw-sectors.m4 \

cmd/zpool_layout/Makefile.in

@@ -51,6 +51,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
 	$(top_srcdir)/config/kernel-blk-end-request.m4 \
 	$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
+	$(top_srcdir)/config/kernel-blk-queue-discard.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-flush.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-io-opt.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-max-hw-sectors.m4 \

cmd/ztest/Makefile.in

@@ -52,6 +52,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
 	$(top_srcdir)/config/kernel-blk-end-request.m4 \
 	$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
+	$(top_srcdir)/config/kernel-blk-queue-discard.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-flush.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-io-opt.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-max-hw-sectors.m4 \

cmd/zvol_id/Makefile.in

@@ -52,6 +52,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
 	$(top_srcdir)/config/kernel-blk-end-request.m4 \
 	$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
+	$(top_srcdir)/config/kernel-blk-queue-discard.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-flush.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-io-opt.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-max-hw-sectors.m4 \

config/kernel-blk-queue-discard.m4

@@ -0,0 +1,22 @@
+dnl #
+dnl # 2.6.32 API change
+dnl # Discard requests were moved to the normal I/O path.
+dnl #
+AC_DEFUN([ZFS_AC_KERNEL_BLK_QUEUE_DISCARD], [
+	AC_MSG_CHECKING([whether blk_queue_discard() is available])
+	tmp_flags="$EXTRA_KCFLAGS"
+	EXTRA_KCFLAGS="-Wno-unused-but-set-variable"
+	ZFS_LINUX_TRY_COMPILE([
+		#include <linux/blkdev.h>
+	],[
+		struct request_queue *q = NULL;
+		(void) blk_queue_discard(q);
+	],[
+		AC_MSG_RESULT(yes)
+		AC_DEFINE(HAVE_BLK_QUEUE_DISCARD, 1,
+		          [blk_queue_discard() is available])
+	],[
+		AC_MSG_RESULT(no)
+	])
+	EXTRA_KCFLAGS="$tmp_flags"
+])

config/kernel.m4

@@ -27,6 +27,7 @@ AC_DEFUN([ZFS_AC_CONFIG_KERNEL], [
 	ZFS_AC_KERNEL_BLK_QUEUE_PHYSICAL_BLOCK_SIZE
 	ZFS_AC_KERNEL_BLK_QUEUE_IO_OPT
 	ZFS_AC_KERNEL_BLK_QUEUE_NONROT
+	ZFS_AC_KERNEL_BLK_QUEUE_DISCARD
 	ZFS_AC_KERNEL_BLK_FETCH_REQUEST
 	ZFS_AC_KERNEL_BLK_REQUEUE_REQUEST
 	ZFS_AC_KERNEL_BLK_RQ_BYTES

configure

@@ -14151,6 +14151,75 @@ $as_echo "no" >&6; }
 
 
 
+fi
+
+	rm -Rf build
+
+
+	EXTRA_KCFLAGS="$tmp_flags"
+
+
+	{ $as_echo "$as_me:$LINENO: checking whether blk_queue_discard() is available" >&5
+$as_echo_n "checking whether blk_queue_discard() is available... " >&6; }
+	tmp_flags="$EXTRA_KCFLAGS"
+	EXTRA_KCFLAGS="-Wno-unused-but-set-variable"
+
+
+cat confdefs.h - <<_ACEOF >conftest.c
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+
+
+		#include <linux/blkdev.h>
+
+int
+main (void)
+{
+
+		struct request_queue *q = NULL;
+		(void) blk_queue_discard(q);
+
+  ;
+  return 0;
+}
+
+_ACEOF
+
+
+	rm -Rf build && mkdir -p build
+	echo "obj-m := conftest.o" >build/Makefile
+	if { ac_try='cp conftest.c build && make modules -C $LINUX_OBJ EXTRA_CFLAGS="-Werror-implicit-function-declaration $EXTRA_KCFLAGS" $ARCH_UM M=$PWD/build'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  $as_echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; } >/dev/null && { ac_try='test -s build/conftest.o'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  $as_echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; }; then
+
+		{ $as_echo "$as_me:$LINENO: result: yes" >&5
+$as_echo "yes" >&6; }
+
+cat >>confdefs.h <<\_ACEOF
+#define HAVE_BLK_QUEUE_DISCARD 1
+_ACEOF
+
+
+else
+  $as_echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+		{ $as_echo "$as_me:$LINENO: result: no" >&5
+$as_echo "no" >&6; }
+
+
+
 fi
 
 	rm -Rf build
@@ -19969,6 +20038,75 @@ $as_echo "no" >&6; }
 
 
 
+fi
+
+	rm -Rf build
+
+
+	EXTRA_KCFLAGS="$tmp_flags"
+
+
+	{ $as_echo "$as_me:$LINENO: checking whether blk_queue_discard() is available" >&5
+$as_echo_n "checking whether blk_queue_discard() is available... " >&6; }
+	tmp_flags="$EXTRA_KCFLAGS"
+	EXTRA_KCFLAGS="-Wno-unused-but-set-variable"
+
+
+cat confdefs.h - <<_ACEOF >conftest.c
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+
+
+		#include <linux/blkdev.h>
+
+int
+main (void)
+{
+
+		struct request_queue *q = NULL;
+		(void) blk_queue_discard(q);
+
+  ;
+  return 0;
+}
+
+_ACEOF
+
+
+	rm -Rf build && mkdir -p build
+	echo "obj-m := conftest.o" >build/Makefile
+	if { ac_try='cp conftest.c build && make modules -C $LINUX_OBJ EXTRA_CFLAGS="-Werror-implicit-function-declaration $EXTRA_KCFLAGS" $ARCH_UM M=$PWD/build'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  $as_echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; } >/dev/null && { ac_try='test -s build/conftest.o'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  $as_echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; }; then
+
+		{ $as_echo "$as_me:$LINENO: result: yes" >&5
+$as_echo "yes" >&6; }
+
+cat >>confdefs.h <<\_ACEOF
+#define HAVE_BLK_QUEUE_DISCARD 1
+_ACEOF
+
+
+else
+  $as_echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+		{ $as_echo "$as_me:$LINENO: result: no" >&5
+$as_echo "no" >&6; }
+
+
+
 fi
 
 	rm -Rf build

dracut/90zfs/Makefile.in

@@ -50,6 +50,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
 	$(top_srcdir)/config/kernel-blk-end-request.m4 \
 	$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
+	$(top_srcdir)/config/kernel-blk-queue-discard.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-flush.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-io-opt.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-max-hw-sectors.m4 \

dracut/Makefile.in

@@ -49,6 +49,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
 	$(top_srcdir)/config/kernel-blk-end-request.m4 \
 	$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
+	$(top_srcdir)/config/kernel-blk-queue-discard.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-flush.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-io-opt.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-max-hw-sectors.m4 \

etc/Makefile.in

@@ -49,6 +49,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
 	$(top_srcdir)/config/kernel-blk-end-request.m4 \
 	$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
+	$(top_srcdir)/config/kernel-blk-queue-discard.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-flush.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-io-opt.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-max-hw-sectors.m4 \

etc/init.d/Makefile.in

@@ -50,6 +50,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
 	$(top_srcdir)/config/kernel-blk-end-request.m4 \
 	$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
+	$(top_srcdir)/config/kernel-blk-queue-discard.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-flush.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-io-opt.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-max-hw-sectors.m4 \

etc/zfs/Makefile.in

@@ -50,6 +50,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
 	$(top_srcdir)/config/kernel-blk-end-request.m4 \
 	$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
+	$(top_srcdir)/config/kernel-blk-queue-discard.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-flush.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-io-opt.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-max-hw-sectors.m4 \

include/Makefile.in

@@ -51,6 +51,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
 	$(top_srcdir)/config/kernel-blk-end-request.m4 \
 	$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
+	$(top_srcdir)/config/kernel-blk-queue-discard.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-flush.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-io-opt.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-max-hw-sectors.m4 \

include/linux/Makefile.in

@@ -51,6 +51,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
 	$(top_srcdir)/config/kernel-blk-end-request.m4 \
 	$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
+	$(top_srcdir)/config/kernel-blk-queue-discard.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-flush.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-io-opt.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-max-hw-sectors.m4 \

include/linux/blkdev_compat.h

@@ -424,6 +424,14 @@ bio_set_flags_failfast(struct block_device *bdev, int *flags)
 # define VDEV_REQ_FUA			REQ_HARDBARRIER
 #endif
 
+/*
+ * 2.6.32 API change
+ * Use the normal I/O patch for discards.
+ */
+#ifdef REQ_DISCARD
+# define VDEV_REQ_DISCARD		REQ_DISCARD
+#endif
+
 /*
  * Default Linux IO Scheduler,
  * Setting the scheduler to noop will allow the Linux IO scheduler to

include/sys/Makefile.in

@@ -51,6 +51,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
 	$(top_srcdir)/config/kernel-blk-end-request.m4 \
 	$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
+	$(top_srcdir)/config/kernel-blk-queue-discard.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-flush.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-io-opt.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-max-hw-sectors.m4 \

include/sys/fm/Makefile.in

@@ -51,6 +51,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
 	$(top_srcdir)/config/kernel-blk-end-request.m4 \
 	$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
+	$(top_srcdir)/config/kernel-blk-queue-discard.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-flush.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-io-opt.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-max-hw-sectors.m4 \

include/sys/fm/fs/Makefile.in

@@ -51,6 +51,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
 	$(top_srcdir)/config/kernel-blk-end-request.m4 \
 	$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
+	$(top_srcdir)/config/kernel-blk-queue-discard.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-flush.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-io-opt.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-max-hw-sectors.m4 \

include/sys/fs/Makefile.in

@@ -51,6 +51,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
 	$(top_srcdir)/config/kernel-blk-end-request.m4 \
 	$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
+	$(top_srcdir)/config/kernel-blk-queue-discard.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-flush.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-io-opt.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-max-hw-sectors.m4 \

lib/Makefile.in

@@ -49,6 +49,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
 	$(top_srcdir)/config/kernel-blk-end-request.m4 \
 	$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
+	$(top_srcdir)/config/kernel-blk-queue-discard.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-flush.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-io-opt.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-max-hw-sectors.m4 \

lib/libavl/Makefile.in

@@ -51,6 +51,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
 	$(top_srcdir)/config/kernel-blk-end-request.m4 \
 	$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
+	$(top_srcdir)/config/kernel-blk-queue-discard.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-flush.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-io-opt.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-max-hw-sectors.m4 \

lib/libefi/Makefile.in

@@ -51,6 +51,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
 	$(top_srcdir)/config/kernel-blk-end-request.m4 \
 	$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
+	$(top_srcdir)/config/kernel-blk-queue-discard.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-flush.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-io-opt.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-max-hw-sectors.m4 \

lib/libnvpair/Makefile.in

@@ -51,6 +51,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
 	$(top_srcdir)/config/kernel-blk-end-request.m4 \
 	$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
+	$(top_srcdir)/config/kernel-blk-queue-discard.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-flush.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-io-opt.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-max-hw-sectors.m4 \

lib/libshare/Makefile.in

@@ -51,6 +51,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
 	$(top_srcdir)/config/kernel-blk-end-request.m4 \
 	$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
+	$(top_srcdir)/config/kernel-blk-queue-discard.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-flush.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-io-opt.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-max-hw-sectors.m4 \

lib/libspl/Makefile.in

@@ -51,6 +51,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
 	$(top_srcdir)/config/kernel-blk-end-request.m4 \
 	$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
+	$(top_srcdir)/config/kernel-blk-queue-discard.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-flush.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-io-opt.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-max-hw-sectors.m4 \

lib/libspl/asm-generic/Makefile.in

@@ -50,6 +50,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
 	$(top_srcdir)/config/kernel-blk-end-request.m4 \
 	$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
+	$(top_srcdir)/config/kernel-blk-queue-discard.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-flush.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-io-opt.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-max-hw-sectors.m4 \

lib/libspl/asm-i386/Makefile.in

@@ -51,6 +51,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
 	$(top_srcdir)/config/kernel-blk-end-request.m4 \
 	$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
+	$(top_srcdir)/config/kernel-blk-queue-discard.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-flush.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-io-opt.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-max-hw-sectors.m4 \

lib/libspl/asm-x86_64/Makefile.in

@@ -51,6 +51,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
 	$(top_srcdir)/config/kernel-blk-end-request.m4 \
 	$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
+	$(top_srcdir)/config/kernel-blk-queue-discard.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-flush.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-io-opt.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-max-hw-sectors.m4 \

lib/libspl/include/Makefile.in

@@ -51,6 +51,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
 	$(top_srcdir)/config/kernel-blk-end-request.m4 \
 	$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
+	$(top_srcdir)/config/kernel-blk-queue-discard.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-flush.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-io-opt.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-max-hw-sectors.m4 \

lib/libspl/include/ia32/Makefile.in

@@ -49,6 +49,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
 	$(top_srcdir)/config/kernel-blk-end-request.m4 \
 	$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
+	$(top_srcdir)/config/kernel-blk-queue-discard.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-flush.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-io-opt.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-max-hw-sectors.m4 \

lib/libspl/include/ia32/sys/Makefile.in

@@ -51,6 +51,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
 	$(top_srcdir)/config/kernel-blk-end-request.m4 \
 	$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
+	$(top_srcdir)/config/kernel-blk-queue-discard.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-flush.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-io-opt.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-max-hw-sectors.m4 \

lib/libspl/include/rpc/Makefile.in

@@ -51,6 +51,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
 	$(top_srcdir)/config/kernel-blk-end-request.m4 \
 	$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
+	$(top_srcdir)/config/kernel-blk-queue-discard.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-flush.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-io-opt.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-max-hw-sectors.m4 \

lib/libspl/include/sys/Makefile.in

@@ -51,6 +51,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
 	$(top_srcdir)/config/kernel-blk-end-request.m4 \
 	$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
+	$(top_srcdir)/config/kernel-blk-queue-discard.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-flush.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-io-opt.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-max-hw-sectors.m4 \

lib/libspl/include/sys/dktp/Makefile.in

@@ -51,6 +51,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
 	$(top_srcdir)/config/kernel-blk-end-request.m4 \
 	$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
+	$(top_srcdir)/config/kernel-blk-queue-discard.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-flush.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-io-opt.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-max-hw-sectors.m4 \

lib/libspl/include/sys/sysevent/Makefile.in

@@ -51,6 +51,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
 	$(top_srcdir)/config/kernel-blk-end-request.m4 \
 	$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
+	$(top_srcdir)/config/kernel-blk-queue-discard.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-flush.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-io-opt.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-max-hw-sectors.m4 \

lib/libspl/include/util/Makefile.in

@@ -51,6 +51,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
 	$(top_srcdir)/config/kernel-blk-end-request.m4 \
 	$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
+	$(top_srcdir)/config/kernel-blk-queue-discard.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-flush.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-io-opt.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-max-hw-sectors.m4 \

lib/libunicode/Makefile.in

@@ -51,6 +51,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
 	$(top_srcdir)/config/kernel-blk-end-request.m4 \
 	$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
+	$(top_srcdir)/config/kernel-blk-queue-discard.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-flush.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-io-opt.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-max-hw-sectors.m4 \

lib/libuutil/Makefile.in

@@ -51,6 +51,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
 	$(top_srcdir)/config/kernel-blk-end-request.m4 \
 	$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
+	$(top_srcdir)/config/kernel-blk-queue-discard.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-flush.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-io-opt.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-max-hw-sectors.m4 \

lib/libzfs/Makefile.in

@@ -51,6 +51,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
 	$(top_srcdir)/config/kernel-blk-end-request.m4 \
 	$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
+	$(top_srcdir)/config/kernel-blk-queue-discard.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-flush.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-io-opt.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-max-hw-sectors.m4 \

lib/libzpool/Makefile.in

@@ -51,6 +51,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
 	$(top_srcdir)/config/kernel-blk-end-request.m4 \
 	$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
+	$(top_srcdir)/config/kernel-blk-queue-discard.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-flush.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-io-opt.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-max-hw-sectors.m4 \

man/Makefile.in

@@ -49,6 +49,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
 	$(top_srcdir)/config/kernel-blk-end-request.m4 \
 	$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
+	$(top_srcdir)/config/kernel-blk-queue-discard.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-flush.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-io-opt.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-max-hw-sectors.m4 \

man/man8/Makefile.in

@@ -49,6 +49,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
 	$(top_srcdir)/config/kernel-blk-end-request.m4 \
 	$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
+	$(top_srcdir)/config/kernel-blk-queue-discard.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-flush.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-io-opt.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-max-hw-sectors.m4 \

module/zfs/zvol.c

@@ -574,6 +574,42 @@ zvol_write(void *arg)
 	blk_end_request(req, -error, size);
 }
 
+#ifdef HAVE_BLK_QUEUE_DISCARD
+static void
+zvol_discard(void *arg)
+{
+	struct request *req = (struct request *)arg;
+	struct request_queue *q = req->q;
+	zvol_state_t *zv = q->queuedata;
+	uint64_t offset = blk_rq_pos(req) << 9;
+	uint64_t size = blk_rq_bytes(req);
+	int error;
+	rl_t *rl;
+
+	if (offset + size > zv->zv_volsize) {
+		blk_end_request(req, -EIO, size);
+		return;
+	}
+
+	if (size == 0) {
+		blk_end_request(req, 0, size);
+		return;
+	}
+
+	rl = zfs_range_lock(&zv->zv_znode, offset, size, RL_WRITER);
+
+	error = dmu_free_long_range(zv->zv_objset, ZVOL_OBJ, offset, size);
+
+	/*
+	 * TODO: maybe we should add the operation to the log.
+	 */
+
+	zfs_range_unlock(rl);
+
+	blk_end_request(req, -error, size);
+}
+#endif /* HAVE_BLK_QUEUE_DISCARD */
+
 /*
  * Common read path running under the zvol taskq context.  This function
  * is responsible for copying the requested data out of the DMU and in to
@@ -674,6 +710,13 @@ zvol_request(struct request_queue *q)
 				break;
 			}
 
+#ifdef HAVE_BLK_QUEUE_DISCARD
+			if (req->cmd_flags & VDEV_REQ_DISCARD) {
+				zvol_dispatch(zvol_discard, req);
+				break;
+			}
+#endif /* HAVE_BLK_QUEUE_DISCARD */
+
 			zvol_dispatch(zvol_write, req);
 			break;
 		default:
@@ -1193,6 +1236,10 @@ __zvol_create_minor(const char *name)
 	blk_queue_max_segment_size(zv->zv_queue, UINT_MAX);
 	blk_queue_physical_block_size(zv->zv_queue, zv->zv_volblocksize);
 	blk_queue_io_opt(zv->zv_queue, zv->zv_volblocksize);
+#ifdef HAVE_BLK_QUEUE_DISCARD
+	blk_queue_max_discard_sectors(zv->zv_queue, UINT_MAX);
+	queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, zv->zv_queue);
+#endif
 #ifdef HAVE_BLK_QUEUE_NONROT
 	queue_flag_set_unlocked(QUEUE_FLAG_NONROT, zv->zv_queue);
 #endif

scripts/Makefile.in

@@ -50,6 +50,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
 	$(top_srcdir)/config/kernel-blk-end-request.m4 \
 	$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
+	$(top_srcdir)/config/kernel-blk-queue-discard.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-flush.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-io-opt.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-max-hw-sectors.m4 \

scripts/zpios-profile/Makefile.in

@@ -50,6 +50,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
 	$(top_srcdir)/config/kernel-blk-end-request.m4 \
 	$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
+	$(top_srcdir)/config/kernel-blk-queue-discard.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-flush.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-io-opt.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-max-hw-sectors.m4 \

scripts/zpios-test/Makefile.in

@@ -50,6 +50,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
 	$(top_srcdir)/config/kernel-blk-end-request.m4 \
 	$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
+	$(top_srcdir)/config/kernel-blk-queue-discard.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-flush.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-io-opt.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-max-hw-sectors.m4 \

scripts/zpool-config/Makefile.in

@@ -50,6 +50,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
 	$(top_srcdir)/config/kernel-blk-end-request.m4 \
 	$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
+	$(top_srcdir)/config/kernel-blk-queue-discard.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-flush.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-io-opt.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-max-hw-sectors.m4 \

scripts/zpool-layout/Makefile.in

@@ -50,6 +50,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
 	$(top_srcdir)/config/kernel-blk-end-request.m4 \
 	$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
+	$(top_srcdir)/config/kernel-blk-queue-discard.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-flush.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-io-opt.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-max-hw-sectors.m4 \

udev/Makefile.in

@@ -49,6 +49,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
 	$(top_srcdir)/config/kernel-blk-end-request.m4 \
 	$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
+	$(top_srcdir)/config/kernel-blk-queue-discard.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-flush.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-io-opt.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-max-hw-sectors.m4 \

udev/rules.d/Makefile.in

@@ -50,6 +50,7 @@ am__aclocal_m4_deps =  \
 	$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
 	$(top_srcdir)/config/kernel-blk-end-request.m4 \
 	$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
+	$(top_srcdir)/config/kernel-blk-queue-discard.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-flush.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-io-opt.m4 \
 	$(top_srcdir)/config/kernel-blk-queue-max-hw-sectors.m4 \

zfs_config.h.in

@@ -51,6 +51,9 @@
 /* blk_fetch_request() is available */
 #undef HAVE_BLK_FETCH_REQUEST
 
+/* blk_queue_discard() is available */
+#undef HAVE_BLK_QUEUE_DISCARD
+
 /* blk_queue_flush() is available */
 #undef HAVE_BLK_QUEUE_FLUSH