From: Vivek Goyal vgoyal@redhat.com
[ Upstream commit 3f9b9efd82a84f27e95d0414f852caf1fa839e83 ]
Right now "mount -t virtiofs -o dax myfs /mnt/virtiofs" succeeds even if filesystem deivce does not have a cache window and hence DAX can't be supported.
This gives a false sense to user that they are using DAX with virtiofs but fact of the matter is that they are not.
Fix this by returning error if dax can't be supported and user has asked for it.
Signed-off-by: Vivek Goyal vgoyal@redhat.com Reviewed-by: Stefan Hajnoczi stefanha@redhat.com Signed-off-by: Miklos Szeredi mszeredi@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/fuse/virtio_fs.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/fs/fuse/virtio_fs.c b/fs/fuse/virtio_fs.c index d2c0e58c6416..3d83c9e12848 100644 --- a/fs/fuse/virtio_fs.c +++ b/fs/fuse/virtio_fs.c @@ -1324,8 +1324,15 @@ static int virtio_fs_fill_super(struct super_block *sb, struct fs_context *fsc)
/* virtiofs allocates and installs its own fuse devices */ ctx->fudptr = NULL; - if (ctx->dax) + if (ctx->dax) { + if (!fs->dax_dev) { + err = -EINVAL; + pr_err("virtio-fs: dax can't be enabled as filesystem" + " device does not support it.\n"); + goto err_free_fuse_devs; + } ctx->dax_dev = fs->dax_dev; + } err = fuse_fill_super_common(sb, ctx); if (err < 0) goto err_free_fuse_devs;