4.17-stable review patch. If anyone has any objections, please let me know.
------------------
From: Ross Zwisler ross.zwisler@linux.intel.com
commit ce7f11a230d5b7165480b96c0cc7a90358b5b5e2 upstream.
Prior to this commit we would only do a "deep flush" (have nvdimm_flush() write to each of the flush hints for a region) in response to an msync/fsync/sync call if the nvdimm_has_cache() returned true at the time we were setting up the request queue. This happens due to the write cache value passed in to blk_queue_write_cache(), which then causes the block layer to send down BIOs with REQ_FUA and REQ_PREFLUSH set. We do have a "write_cache" sysfs entry for namespaces, i.e.:
/sys/bus/nd/devices/pfn0.1/block/pmem0/dax/write_cache
which can be used to control whether or not the kernel thinks a given namespace has a write cache, but this didn't modify the deep flush behavior that we set up when the driver was initialized. Instead, it only modified whether or not DAX would flush CPU caches via dax_flush() in response to *sync calls.
Simplify this by making the *sync deep flush always happen, regardless of the write cache setting of a namespace. The DAX CPU cache flushing will still be controlled the write_cache setting of the namespace.
Cc: stable@vger.kernel.org Fixes: 5fdf8e5ba566 ("libnvdimm: re-enable deep flush for pmem devices via fsync()") Signed-off-by: Ross Zwisler ross.zwisler@linux.intel.com Signed-off-by: Dan Williams dan.j.williams@intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/nvdimm/pmem.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-)
--- a/drivers/nvdimm/pmem.c +++ b/drivers/nvdimm/pmem.c @@ -299,7 +299,7 @@ static int pmem_attach_disk(struct devic { struct nd_namespace_io *nsio = to_nd_namespace_io(&ndns->dev); struct nd_region *nd_region = to_nd_region(dev->parent); - int nid = dev_to_node(dev), fua, wbc; + int nid = dev_to_node(dev), fua; struct resource *res = &nsio->res; struct resource bb_res; struct nd_pfn *nd_pfn = NULL; @@ -335,7 +335,6 @@ static int pmem_attach_disk(struct devic dev_warn(dev, "unable to guarantee persistence of writes\n"); fua = 0; } - wbc = nvdimm_has_cache(nd_region);
if (!devm_request_mem_region(dev, res->start, resource_size(res), dev_name(&ndns->dev))) { @@ -382,7 +381,7 @@ static int pmem_attach_disk(struct devic return PTR_ERR(addr); pmem->virt_addr = addr;
- blk_queue_write_cache(q, wbc, fua); + blk_queue_write_cache(q, true, fua); blk_queue_make_request(q, pmem_make_request); blk_queue_physical_block_size(q, PAGE_SIZE); blk_queue_logical_block_size(q, pmem_sector_size(ndns)); @@ -413,7 +412,7 @@ static int pmem_attach_disk(struct devic put_disk(disk); return -ENOMEM; } - dax_write_cache(dax_dev, wbc); + dax_write_cache(dax_dev, nvdimm_has_cache(nd_region)); pmem->dax_dev = dax_dev;
gendev = disk_to_dev(disk);