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 <[email protected]>

21 files changed, 21 insertions, 0 deletions

diff --git a/lib/Makefile.in b/lib/Makefile.in
index 43bdf0dc2..daaf306b1 100644
--- a/lib/Makefile.in
+++ b/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 \
diff --git a/lib/libavl/Makefile.in b/lib/libavl/Makefile.in
index d909fa66a..d28c6acde 100644
--- a/lib/libavl/Makefile.in
+++ b/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 \
diff --git a/lib/libefi/Makefile.in b/lib/libefi/Makefile.in
index a0595ce5d..4a935784a 100644
--- a/lib/libefi/Makefile.in
+++ b/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 \
diff --git a/lib/libnvpair/Makefile.in b/lib/libnvpair/Makefile.in
index 533d96235..e982a68bd 100644
--- a/lib/libnvpair/Makefile.in
+++ b/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 \
diff --git a/lib/libshare/Makefile.in b/lib/libshare/Makefile.in
index 8390ce835..61b61a700 100644
--- a/lib/libshare/Makefile.in
+++ b/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 \
diff --git a/lib/libspl/Makefile.in b/lib/libspl/Makefile.in
index 541f72b9d..2d1a8ad17 100644
--- a/lib/libspl/Makefile.in
+++ b/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 \
diff --git a/lib/libspl/asm-generic/Makefile.in b/lib/libspl/asm-generic/Makefile.in
index 974f489ad..63b0ef392 100644
--- a/lib/libspl/asm-generic/Makefile.in
+++ b/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 \
diff --git a/lib/libspl/asm-i386/Makefile.in b/lib/libspl/asm-i386/Makefile.in
index f84cd39d9..2d43d8918 100644
--- a/lib/libspl/asm-i386/Makefile.in
+++ b/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 \
diff --git a/lib/libspl/asm-x86_64/Makefile.in b/lib/libspl/asm-x86_64/Makefile.in
index 23c4b2917..c6d61a5fa 100644
--- a/lib/libspl/asm-x86_64/Makefile.in
+++ b/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 \
diff --git a/lib/libspl/include/Makefile.in b/lib/libspl/include/Makefile.in
index 043f0fe1e..ab1d8511e 100644
--- a/lib/libspl/include/Makefile.in
+++ b/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 \
diff --git a/lib/libspl/include/ia32/Makefile.in b/lib/libspl/include/ia32/Makefile.in
index dad5d8561..f1f6cb87f 100644
--- a/lib/libspl/include/ia32/Makefile.in
+++ b/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 \
diff --git a/lib/libspl/include/ia32/sys/Makefile.in b/lib/libspl/include/ia32/sys/Makefile.in
index d7ea24fff..70eb6a35d 100644
--- a/lib/libspl/include/ia32/sys/Makefile.in
+++ b/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 \
diff --git a/lib/libspl/include/rpc/Makefile.in b/lib/libspl/include/rpc/Makefile.in
index 3a0b3a1af..a217ab6dc 100644
--- a/lib/libspl/include/rpc/Makefile.in
+++ b/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 \
diff --git a/lib/libspl/include/sys/Makefile.in b/lib/libspl/include/sys/Makefile.in
index b8663bdd2..efa77adc6 100644
--- a/lib/libspl/include/sys/Makefile.in
+++ b/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 \
diff --git a/lib/libspl/include/sys/dktp/Makefile.in b/lib/libspl/include/sys/dktp/Makefile.in
index e5c353795..1656d9d4e 100644
--- a/lib/libspl/include/sys/dktp/Makefile.in
+++ b/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 \
diff --git a/lib/libspl/include/sys/sysevent/Makefile.in b/lib/libspl/include/sys/sysevent/Makefile.in
index edb36b071..5a37394e3 100644
--- a/lib/libspl/include/sys/sysevent/Makefile.in
+++ b/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 \
diff --git a/lib/libspl/include/util/Makefile.in b/lib/libspl/include/util/Makefile.in
index 301fde587..8894eb57a 100644
--- a/lib/libspl/include/util/Makefile.in
+++ b/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 \
diff --git a/lib/libunicode/Makefile.in b/lib/libunicode/Makefile.in
index 3e3cb2df1..6135529f8 100644
--- a/lib/libunicode/Makefile.in
+++ b/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 \
diff --git a/lib/libuutil/Makefile.in b/lib/libuutil/Makefile.in
index 1fb5e573d..e10118898 100644
--- a/lib/libuutil/Makefile.in
+++ b/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 \
diff --git a/lib/libzfs/Makefile.in b/lib/libzfs/Makefile.in
index 9ba47ca73..84e9e2a7e 100644
--- a/lib/libzfs/Makefile.in
+++ b/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 \
diff --git a/lib/libzpool/Makefile.in b/lib/libzpool/Makefile.in
index fc071e22a..6c6b3b1e7 100644
--- a/lib/libzpool/Makefile.in
+++ b/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 \