linux-kernel - [PATCH] libnvdimm: fix blk free space accounting

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Date:   Sat, 01 Apr 2017 12:26:44 -0700
From:   Dan Williams <dan.j.williams@...el.com>
To:     linux-nvdimm@...ts.01.org
Cc:     Dave Jiang <dave.jiang@...el.com>, linux-kernel@...r.kernel.org,
        stable@...r.kernel.org
Subject: [PATCH] libnvdimm: fix blk free space accounting

Commit a1f3e4d6a0c3 "libnvdimm, region: update nd_region_available_dpa()
for multi-pmem support" reworked blk dpa (DIMM Physical Address)
accounting to comprehend multiple pmem namespace allocations aliasing
with a given blk-dpa range.

The following call trace is a result of failing to account for allocated
blk capacity.

 WARNING: CPU: 1 PID: 2433 at tools/testing/nvdimm/../../../drivers/nvdimm/names
4 size_store+0x6f3/0x930 [libnvdimm]
 nd_region region5: allocation underrun: 0x0 of 0x1000000 bytes
 [..]
 Call Trace:
  dump_stack+0x86/0xc3
  __warn+0xcb/0xf0
  warn_slowpath_fmt+0x5f/0x80
  size_store+0x6f3/0x930 [libnvdimm]
  dev_attr_store+0x18/0x30

If a given blk-dpa allocation does not alias with any pmem ranges then
the full allocation should be accounted as busy space, not the size of
the current pmem contribution to the region.

Cc: <stable@...r.kernel.org>
Fixes: a1f3e4d6a0c3 ("libnvdimm, region: update nd_region_available_dpa() for multi-pmem support").
Reported-by: Dave Jiang <dave.jiang@...el.com>
Signed-off-by: Dan Williams <dan.j.williams@...el.com>
---
 drivers/nvdimm/dimm_devs.c |    4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/nvdimm/dimm_devs.c b/drivers/nvdimm/dimm_devs.c
index 0eedc49e0d47..ba1143b1b2ca 100644
--- a/drivers/nvdimm/dimm_devs.c
+++ b/drivers/nvdimm/dimm_devs.c
@@ -510,10 +510,8 @@ static int blk_dpa_busy(struct device *dev, void *data)
 			&& info->res->end <= map_end) {
 		info->busy -= nd_mapping->start - info->res->start;
 		return 0;
-	} else {
-		info->busy -= nd_mapping->size;
-		return 0;
 	}
+	return 0;
 }
 
 /**