Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
From:   Pankaj Gupta <pagupta@redhat.com>
To:     dm-devel@redhat.com, linux-nvdimm@lists.01.org,
        linux-kernel@vger.kernel.org,
        virtualization@lists.linux-foundation.org, kvm@vger.kernel.org,
        linux-fsdevel@vger.kernel.org, linux-acpi@vger.kernel.org,
        qemu-devel@nongnu.org, linux-ext4@vger.kernel.org,
        linux-xfs@vger.kernel.org
Cc:     dan.j.williams@intel.com, zwisler@kernel.org,
        vishal.l.verma@intel.com, dave.jiang@intel.com, mst@redhat.com,
        jasowang@redhat.com, willy@infradead.org, rjw@rjwysocki.net,
        hch@infradead.org, lenb@kernel.org, jack@suse.cz, tytso@mit.edu,
        adilger.kernel@dilger.ca, darrick.wong@oracle.com,
        lcapitulino@redhat.com, kwolf@redhat.com, imammedo@redhat.com,
        jmoyer@redhat.com, nilal@redhat.com, riel@surriel.com,
        stefanha@redhat.com, aarcange@redhat.com, david@redhat.com,
        david@fromorbit.com, cohuck@redhat.com,
        xiaoguangrong.eric@gmail.com, pagupta@redhat.com,
        pbonzini@redhat.com, yuval.shaia@oracle.com, kilobyte@angband.pl,
        jstaron@google.com, rdunlap@infradead.org, snitzer@redhat.com
Subject: [PATCH v14 5/7] dax: check synchronous mapping is supported
Date:   Fri, 21 Jun 2019 19:04:53 +0530
Message-Id: <20190621133455.3303-6-pagupta@redhat.com>
In-Reply-To: <20190621133455.3303-1-pagupta@redhat.com>
References: <20190621133455.3303-1-pagupta@redhat.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

This patch introduces 'daxdev_mapping_supported' helper
which checks if 'MAP_SYNC' is supported with filesystem
mapping. It also checks if corresponding dax_device is
synchronous. Virtio pmem device is asynchronous and
does not not support VM_SYNC.

Suggested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Pankaj Gupta <pagupta@redhat.com>
Reviewed-by: Jan Kara <jack@suse.cz>
---
 include/linux/dax.h | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/include/linux/dax.h b/include/linux/dax.h
index 86fc55c99b58..d1bea3979b5a 100644
--- a/include/linux/dax.h
+++ b/include/linux/dax.h
@@ -53,6 +53,18 @@ static inline void set_dax_synchronous(struct dax_device *dax_dev)
 {
 	__set_dax_synchronous(dax_dev);
 }
+/*
+ * Check if given mapping is supported by the file / underlying device.
+ */
+static inline bool daxdev_mapping_supported(struct vm_area_struct *vma,
+					     struct dax_device *dax_dev)
+{
+	if (!(vma->vm_flags & VM_SYNC))
+		return true;
+	if (!IS_DAX(file_inode(vma->vm_file)))
+		return false;
+	return dax_synchronous(dax_dev);
+}
 #else
 static inline struct dax_device *dax_get_by_host(const char *host)
 {
@@ -87,6 +99,11 @@ static inline bool dax_synchronous(struct dax_device *dax_dev)
 static inline void set_dax_synchronous(struct dax_device *dax_dev)
 {
 }
+static inline bool daxdev_mapping_supported(struct vm_area_struct *vma,
+				struct dax_device *dax_dev)
+{
+	return !(vma->vm_flags & VM_SYNC);
+}
 #endif
 
 struct writeback_control;
-- 
2.20.1