[PATCH v2 4/5] HOWTO/man: Describe trim support by zone reset for zoned devices

[Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>]

Previous commits added trim support for zoned devices. Update HOWTO and
man page to describe it. Also add missing description about libzbc I/O
engine to HOWTO.

Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
---
 HOWTO | 9 +++++++++
 fio.1 | 4 +++-
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/HOWTO b/HOWTO
index d4e620de..b5d71475 100644
--- a/HOWTO
+++ b/HOWTO
@@ -992,6 +992,9 @@ Target file/device
 				single zone. The :option:`zoneskip` parameter
 				is ignored. :option:`zonerange` and
 				:option:`zonesize` must be identical.
+				Trim is handled using a zone reset operation.
+				Trim only considers non-empty sequential write
+				required and sequential write preferred zones.
 
 .. option:: zonerange=int
 
@@ -1965,6 +1968,12 @@ I/O engine
 			character devices. This engine supports trim operations.
 			The sg engine includes engine specific options.
 
+		**libzbc**
+			Synchronous I/O engine for SMR hard-disks using the libzbc
+			library. The target can be either an sg character device or
+			a block device file. This engine supports the zonemode=zbd zone
+			operations and read/write/trim I/Os.
+
 		**null**
 			Doesn't transfer any data, just pretends to.  This is mainly used to
 			exercise fio itself and for debugging/testing purposes.
diff --git a/fio.1 b/fio.1
index 9c12ad13..c0e83fef 100644
--- a/fio.1
+++ b/fio.1
@@ -766,6 +766,8 @@ starts. The \fBzonecapacity\fR parameter is ignored.
 Zoned block device mode. I/O happens sequentially in each zone, even if random
 I/O has been selected. Random I/O happens across all zones instead of being
 restricted to a single zone.
+Trim is handled using a zone reset operation. Trim only considers non-empty
+sequential write required and sequential write preferred zones.
 .RE
 .RE
 .TP
@@ -1764,7 +1766,7 @@ sg engine includes engine specific options.
 Synchronous I/O engine for SMR hard-disks using the \fBlibzbc\fR
 library. The target can be either an sg character device or
 a block device file. This engine supports the zonemode=zbd zone
-operations.
+operations and read/write/trim I/Os.
 .TP
 .B null
 Doesn't transfer any data, just pretends to. This is mainly used to
-- 
2.31.1