linux-ext4 - [PATCH v6 6/6] xfs: disable map

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Message-Id: <20190423080612.15361-7-pagupta@redhat.com>
Date:   Tue, 23 Apr 2019 13:36:12 +0530
From:   Pankaj Gupta <pagupta@...hat.com>
To:     linux-nvdimm@...ts.01.org, linux-kernel@...r.kernel.org,
        virtualization@...ts.linux-foundation.org, kvm@...r.kernel.org,
        linux-fsdevel@...r.kernel.org, linux-acpi@...r.kernel.org,
        qemu-devel@...gnu.org, linux-ext4@...r.kernel.org,
        linux-xfs@...r.kernel.org
Cc:     dan.j.williams@...el.com, zwisler@...nel.org,
        vishal.l.verma@...el.com, dave.jiang@...el.com, mst@...hat.com,
        jasowang@...hat.com, willy@...radead.org, rjw@...ysocki.net,
        hch@...radead.org, lenb@...nel.org, jack@...e.cz, tytso@....edu,
        adilger.kernel@...ger.ca, darrick.wong@...cle.com,
        lcapitulino@...hat.com, kwolf@...hat.com, imammedo@...hat.com,
        jmoyer@...hat.com, nilal@...hat.com, riel@...riel.com,
        stefanha@...hat.com, aarcange@...hat.com, david@...hat.com,
        david@...morbit.com, cohuck@...hat.com,
        xiaoguangrong.eric@...il.com, pagupta@...hat.com,
        pbonzini@...hat.com, yuval.shaia@...cle.com, kilobyte@...band.pl
Subject: [PATCH v6 6/6] xfs: disable map_sync for async flush

Dont support 'MAP_SYNC' with non-DAX files and DAX files
with asynchronous dax_device. Virtio pmem provides
asynchronous host page cache flush mechanism. We don't
support 'MAP_SYNC' with virtio pmem and xfs.

Signed-off-by: Pankaj Gupta <pagupta@...hat.com>
---
 fs/xfs/xfs_file.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 1f2e2845eb76..0e59be018511 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -1196,11 +1196,13 @@ xfs_file_mmap(
 	struct file	*filp,
 	struct vm_area_struct *vma)
 {
-	/*
-	 * We don't support synchronous mappings for non-DAX files. At least
-	 * until someone comes with a sensible use case.
+	struct dax_device *dax_dev = xfs_find_daxdev_for_inode
+						(file_inode(filp));
+
+	/* We don't support synchronous mappings for non-DAX files and
+	 * for DAX files if underneath dax_device is not synchronous.
 	 */
-	if (!IS_DAX(file_inode(filp)) && (vma->vm_flags & VM_SYNC))
+	if (!daxdev_mapping_supported(vma, dax_dev))
 		return -EOPNOTSUPP;
 
 	file_accessed(filp);
-- 
2.20.1