[Devel] [PATCH RHEL7 COMMIT] ploop: Show whether device supports native discard

[Konstantin Khorenko]

The commit is pushed to "branch-rh7-3.10.0-957.12.2.vz7.96.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-957.12.2.vz7.96.1
------>
commit ac7df67d45761b1d03e089b98da7455bb656762f
Author: Kirill Tkhai <ktkhai at virtuozzo.com>
Date:   Tue May 21 17:44:29 2019 +0300

    ploop: Show whether device supports native discard
    
    ... or not support discard at all.
    
    Shown in: /sys/block/ploopXXX/pstate/discard_mode
    
    Signed-off-by: Kirill Tkhai <ktkhai at virtuozzo.com>
    
    =====================
    Patchset description:
    
    ploop: Return maintaince mode
    
    This patch set enables it for vstorage.
    
    Also, added file /sys/block/ploopXXX/pstate/native_discard,
    which shows, whether we should use maintaince-mode based
    discard or not.
    
    https://jira.sw.ru/browse/PSBM-94662
    
    Kirill Tkhai (8):
          Revert "ploop: Remove now unused PLOOP_E_ZERO_INDEX and PLOOP_E_DELTA_ZERO_INDEX branches"
          Revert "ploop: Remove now unused PLOOP_REQ_RELOC_S branches"
          Revert "ploop: Remove now unused PLOOP_REQ_DISCARD branches"
          Revert "ploop: Remove now unused PLOOP_REQ_ZERO branches"
          Revert "ploop: Remove obsolete ioctls"
          Partial revert "ploop: Enable native discard support for kaio engine"
          ploop: Return maintaince mode ioctls again
          ploop: Show whether device supports native discard
---
 drivers/block/ploop/sysfs.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/block/ploop/sysfs.c b/drivers/block/ploop/sysfs.c
index b2203d152c2c..705ad36b6e41 100644
--- a/drivers/block/ploop/sysfs.c
+++ b/drivers/block/ploop/sysfs.c
@@ -484,6 +484,17 @@ static u32 show_freeze_state(struct ploop_device * plo)
 	return plo->freeze_state;
 }
 
+static u32 show_discard_mode(struct ploop_device *plo)
+{
+	/*
+	 * 0 - discard disabled (not implemented)
+	 * 1 - maintaince mode-based discard
+	 * 2 - hole-based discard
+	 * 3 - move-tail-block discard (not implemented)
+	 */
+	return test_bit(PLOOP_S_NO_FALLOC_DISCARD, &plo->state) ? 1 : 2;
+}
+
 #define _TUNE_U32(_name)				\
 static u32 show_##_name(struct ploop_device * plo)	\
 {							\
@@ -571,6 +582,7 @@ static struct attribute *state_attributes[] = {
 	_A(blockable_reqs),
 	_A(blocked_bios),
 	_A(freeze_state),
+	_A(discard_mode),
 	NULL
 };