virtiofs: add a mount option to enable dax

Add a mount option to allow using dax with virtio_fs.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

1 files changed, 67 insertions, 14 deletions

diff --git a/fs/fuse/virtio_fs.c b/fs/fuse/virtio_fs.c
index f31a59f74475..e25f62276050 100644
--- a/fs/fuse/virtio_fs.c
+++ b/fs/fuse/virtio_fs.c
@@ -13,6 +13,7 @@
 #include <linux/virtio_fs.h>
 #include <linux/delay.h>
 #include <linux/fs_context.h>
+#include <linux/fs_parser.h>
 #include <linux/highmem.h>
 #include <linux/uio.h>
 #include "fuse_i.h"
@@ -81,6 +82,44 @@ struct virtio_fs_req_work {
 static int virtio_fs_enqueue_req(struct virtio_fs_vq *fsvq,
 				 struct fuse_req *req, bool in_flight);
 
+enum {
+	OPT_DAX,
+};
+
+static const struct fs_parameter_spec virtio_fs_parameters[] = {
+	fsparam_flag("dax", OPT_DAX),
+	{}
+};
+
+static int virtio_fs_parse_param(struct fs_context *fc,
+				 struct fs_parameter *param)
+{
+	struct fs_parse_result result;
+	struct fuse_fs_context *ctx = fc->fs_private;
+	int opt;
+
+	opt = fs_parse(fc, virtio_fs_parameters, param, &result);
+	if (opt < 0)
+		return opt;
+
+	switch (opt) {
+	case OPT_DAX:
+		ctx->dax = 1;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static void virtio_fs_free_fc(struct fs_context *fc)
+{
+	struct fuse_fs_context *ctx = fc->fs_private;
+
+	kfree(ctx);
+}
+
 static inline struct virtio_fs_vq *vq_to_fsvq(struct virtqueue *vq)
 {
 	struct virtio_fs *fs = vq->vdev->priv;
@@ -1219,23 +1258,27 @@ static const struct fuse_iqueue_ops virtio_fs_fiq_ops = {
 	.release			= virtio_fs_fiq_release,
 };
 
-static int virtio_fs_fill_super(struct super_block *sb)
+static inline void virtio_fs_ctx_set_defaults(struct fuse_fs_context *ctx)
+{
+	ctx->rootmode = S_IFDIR;
+	ctx->default_permissions = 1;
+	ctx->allow_other = 1;
+	ctx->max_read = UINT_MAX;
+	ctx->blksize = 512;
+	ctx->destroy = true;
+	ctx->no_control = true;
+	ctx->no_force_umount = true;
+}
+
+static int virtio_fs_fill_super(struct super_block *sb, struct fs_context *fsc)
 {
 	struct fuse_conn *fc = get_fuse_conn_super(sb);
 	struct virtio_fs *fs = fc->iq.priv;
+	struct fuse_fs_context *ctx = fsc->fs_private;
 	unsigned int i;
 	int err;
-	struct fuse_fs_context ctx = {
-		.rootmode = S_IFDIR,
-		.default_permissions = 1,
-		.allow_other = 1,
-		.max_read = UINT_MAX,
-		.blksize = 512,
-		.destroy = true,
-		.no_control = true,
-		.no_force_umount = true,
-	};
 
+	virtio_fs_ctx_set_defaults(ctx);
 	mutex_lock(&virtio_fs_mutex);
 
 	/* After holding mutex, make sure virtiofs device is still there.
@@ -1259,8 +1302,10 @@ static int virtio_fs_fill_super(struct super_block *sb)
 	}
 
 	/* virtiofs allocates and installs its own fuse devices */
-	ctx.fudptr = NULL;
-	err = fuse_fill_super_common(sb, &ctx);
+	ctx->fudptr = NULL;
+	if (ctx->dax)
+		ctx->dax_dev = fs->dax_dev;
+	err = fuse_fill_super_common(sb, ctx);
 	if (err < 0)
 		goto err_free_fuse_devs;
 
@@ -1371,7 +1416,7 @@ static int virtio_fs_get_tree(struct fs_context *fsc)
 		return PTR_ERR(sb);
 
 	if (!sb->s_root) {
-		err = virtio_fs_fill_super(sb);
+		err = virtio_fs_fill_super(sb, fsc);
 		if (err) {
 			deactivate_locked_super(sb);
 			return err;
@@ -1386,11 +1431,19 @@ static int virtio_fs_get_tree(struct fs_context *fsc)
 }
 
 static const struct fs_context_operations virtio_fs_context_ops = {
+	.free		= virtio_fs_free_fc,
+	.parse_param	= virtio_fs_parse_param,
 	.get_tree	= virtio_fs_get_tree,
 };
 
 static int virtio_fs_init_fs_context(struct fs_context *fsc)
 {
+	struct fuse_fs_context *ctx;
+
+	ctx = kzalloc(sizeof(struct fuse_fs_context), GFP_KERNEL);
+	if (!ctx)
+		return -ENOMEM;
+	fsc->fs_private = ctx;
 	fsc->ops = &virtio_fs_context_ops;
 	return 0;
 }