4 files changed, 52 insertions, 9 deletions

diff --git a/fs/fuse/dax.c b/fs/fuse/dax.c
index 8057fbf5576c..d2bc5e7f5132 100644
--- a/fs/fuse/dax.c
+++ b/fs/fuse/dax.c
@@ -1279,11 +1279,14 @@ out_err:
 	return ret;
 }
 
-int fuse_dax_conn_alloc(struct fuse_conn *fc, struct dax_device *dax_dev)
+int fuse_dax_conn_alloc(struct fuse_conn *fc, enum fuse_dax_mode dax_mode,
+			struct dax_device *dax_dev)
 {
 	struct fuse_conn_dax *fcd;
 	int err;
 
+	fc->dax_mode = dax_mode;
+
 	if (!dax_dev)
 		return 0;
 
@@ -1330,7 +1333,15 @@ static const struct address_space_operations fuse_dax_file_aops  = {
 static bool fuse_should_enable_dax(struct inode *inode)
 {
 	struct fuse_conn *fc = get_fuse_conn(inode);
+	enum fuse_dax_mode dax_mode = fc->dax_mode;
+
+	if (dax_mode == FUSE_DAX_NEVER)
+		return false;
 
+	/*
+	 * fc->dax may be NULL in 'inode' mode when filesystem device doesn't
+	 * support DAX, in which case it will silently fallback to 'never' mode.
+	 */
 	if (!fc->dax)
 		return false;
 
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index c1a8b313e6ed..8bf133109170 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -480,6 +480,18 @@ struct fuse_dev {
 	struct list_head entry;
 };
 
+enum fuse_dax_mode {
+	FUSE_DAX_INODE_DEFAULT,	/* default */
+	FUSE_DAX_ALWAYS,	/* "-o dax=always" */
+	FUSE_DAX_NEVER,		/* "-o dax=never" */
+	FUSE_DAX_INODE_USER,	/* "-o dax=inode" */
+};
+
+static inline bool fuse_is_inode_dax_mode(enum fuse_dax_mode mode)
+{
+	return mode == FUSE_DAX_INODE_DEFAULT || mode == FUSE_DAX_INODE_USER;
+}
+
 struct fuse_fs_context {
 	int fd;
 	struct file *file;
@@ -497,7 +509,7 @@ struct fuse_fs_context {
 	bool no_control:1;
 	bool no_force_umount:1;
 	bool legacy_opts_show:1;
-	bool dax:1;
+	enum fuse_dax_mode dax_mode;
 	unsigned int max_read;
 	unsigned int blksize;
 	const char *subtype;
@@ -805,6 +817,9 @@ struct fuse_conn {
 	struct list_head devices;
 
 #ifdef CONFIG_FUSE_DAX
+	/* Dax mode */
+	enum fuse_dax_mode dax_mode;
+
 	/* Dax specific conn data, non-NULL if DAX is enabled */
 	struct fuse_conn_dax *dax;
 #endif
@@ -1272,7 +1287,8 @@ ssize_t fuse_dax_read_iter(struct kiocb *iocb, struct iov_iter *to);
 ssize_t fuse_dax_write_iter(struct kiocb *iocb, struct iov_iter *from);
 int fuse_dax_mmap(struct file *file, struct vm_area_struct *vma);
 int fuse_dax_break_layouts(struct inode *inode, u64 dmap_start, u64 dmap_end);
-int fuse_dax_conn_alloc(struct fuse_conn *fc, struct dax_device *dax_dev);
+int fuse_dax_conn_alloc(struct fuse_conn *fc, enum fuse_dax_mode mode,
+			struct dax_device *dax_dev);
 void fuse_dax_conn_free(struct fuse_conn *fc);
 bool fuse_dax_inode_alloc(struct super_block *sb, struct fuse_inode *fi);
 void fuse_dax_inode_init(struct inode *inode);
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index 63ab45427de5..d83589ef11c0 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -767,8 +767,12 @@ static int fuse_show_options(struct seq_file *m, struct dentry *root)
 			seq_printf(m, ",blksize=%lu", sb->s_blocksize);
 	}
 #ifdef CONFIG_FUSE_DAX
-	if (fc->dax)
-		seq_puts(m, ",dax");
+	if (fc->dax_mode == FUSE_DAX_ALWAYS)
+		seq_puts(m, ",dax=always");
+	else if (fc->dax_mode == FUSE_DAX_NEVER)
+		seq_puts(m, ",dax=never");
+	else if (fc->dax_mode == FUSE_DAX_INODE_USER)
+		seq_puts(m, ",dax=inode");
 #endif
 
 	return 0;
@@ -1523,7 +1527,7 @@ int fuse_fill_super_common(struct super_block *sb, struct fuse_fs_context *ctx)
 	sb->s_subtype = ctx->subtype;
 	ctx->subtype = NULL;
 	if (IS_ENABLED(CONFIG_FUSE_DAX)) {
-		err = fuse_dax_conn_alloc(fc, ctx->dax_dev);
+		err = fuse_dax_conn_alloc(fc, ctx->dax_mode, ctx->dax_dev);
 		if (err)
 			goto err;
 	}
diff --git a/fs/fuse/virtio_fs.c b/fs/fuse/virtio_fs.c
index 4cfa4bc1f579..e54dc069587d 100644
--- a/fs/fuse/virtio_fs.c
+++ b/fs/fuse/virtio_fs.c
@@ -88,12 +88,21 @@ struct virtio_fs_req_work {
 static int virtio_fs_enqueue_req(struct virtio_fs_vq *fsvq,
 				 struct fuse_req *req, bool in_flight);
 
+static const struct constant_table dax_param_enums[] = {
+	{"always",	FUSE_DAX_ALWAYS },
+	{"never",	FUSE_DAX_NEVER },
+	{"inode",	FUSE_DAX_INODE_USER },
+	{}
+};
+
 enum {
 	OPT_DAX,
+	OPT_DAX_ENUM,
 };
 
 static const struct fs_parameter_spec virtio_fs_parameters[] = {
 	fsparam_flag("dax", OPT_DAX),
+	fsparam_enum("dax", OPT_DAX_ENUM, dax_param_enums),
 	{}
 };
 
@@ -110,7 +119,10 @@ static int virtio_fs_parse_param(struct fs_context *fsc,
 
 	switch (opt) {
 	case OPT_DAX:
-		ctx->dax = 1;
+		ctx->dax_mode = FUSE_DAX_ALWAYS;
+		break;
+	case OPT_DAX_ENUM:
+		ctx->dax_mode = result.uint_32;
 		break;
 	default:
 		return -EINVAL;
@@ -1326,8 +1338,8 @@ 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 (!fs->dax_dev) {
+	if (ctx->dax_mode != FUSE_DAX_NEVER) {
+		if (ctx->dax_mode == FUSE_DAX_ALWAYS && !fs->dax_dev) {
 			err = -EINVAL;
 			pr_err("virtio-fs: dax can't be enabled as filesystem"
 			       " device does not support it.\n");