Add a mount option to allow using dax with virtio_fs.

Signed-off-by: Vivek Goyal <[email protected]>
---
 fs/fuse/fuse_i.h    |  7 ++++
 fs/fuse/inode.c     |  3 ++
 fs/fuse/virtio_fs.c | 82 +++++++++++++++++++++++++++++++++++++--------
 3 files changed, 78 insertions(+), 14 deletions(-)

diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 2cebdf6dcfd8..1fe5065a2902 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -483,10 +483,14 @@ struct fuse_fs_context {
        bool destroy:1;
        bool no_control:1;
        bool no_force_umount:1;
+       bool dax:1;
        unsigned int max_read;
        unsigned int blksize;
        const char *subtype;
 
+       /* DAX device, may be NULL */
+       struct dax_device *dax_dev;
+
        /* fuse_dev pointer to fill in, should contain NULL on entry */
        void **fudptr;
 };
@@ -758,6 +762,9 @@ struct fuse_conn {
 
        /** List of device instances belonging to this connection */
        struct list_head devices;
+
+       /** DAX device, non-NULL if DAX is supported */
+       struct dax_device *dax_dev;
 };
 
 static inline struct fuse_conn *get_fuse_conn_super(struct super_block *sb)
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index f160a3d47b63..84295fac4ff3 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -569,6 +569,8 @@ static int fuse_show_options(struct seq_file *m, struct 
dentry *root)
                seq_printf(m, ",max_read=%u", fc->max_read);
        if (sb->s_bdev && sb->s_blocksize != FUSE_DEFAULT_BLKSIZE)
                seq_printf(m, ",blksize=%lu", sb->s_blocksize);
+       if (fc->dax_dev)
+               seq_printf(m, ",dax");
        return 0;
 }
 
@@ -1185,6 +1187,7 @@ int fuse_fill_super_common(struct super_block *sb, struct 
fuse_fs_context *ctx)
        fc->destroy = ctx->destroy;
        fc->no_control = ctx->no_control;
        fc->no_force_umount = ctx->no_force_umount;
+       fc->dax_dev = ctx->dax_dev;
 
        err = -ENOMEM;
        root = fuse_get_root_inode(sb, ctx->rootmode);
diff --git a/fs/fuse/virtio_fs.c b/fs/fuse/virtio_fs.c
index 3f786a15b0d9..62cdd6817b5b 100644
--- a/fs/fuse/virtio_fs.c
+++ b/fs/fuse/virtio_fs.c
@@ -10,6 +10,7 @@
 #include <linux/virtio_fs.h>
 #include <linux/delay.h>
 #include <linux/fs_context.h>
+#include <linux/fs_parser.h>
 #include <linux/highmem.h>
 #include "fuse_i.h"
 
@@ -65,6 +66,45 @@ struct virtio_fs_forget {
 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;
+
+       if (ctx)
+               kfree(ctx);
+}
+
 static inline struct virtio_fs_vq *vq_to_fsvq(struct virtqueue *vq)
 {
        struct virtio_fs *fs = vq->vdev->priv;
@@ -1045,23 +1085,27 @@ 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.
@@ -1084,8 +1128,10 @@ static int virtio_fs_fill_super(struct super_block *sb)
                        goto err_free_fuse_devs;
        }
 
-       ctx.fudptr = (void **)&fs->vqs[VQ_REQUEST].fud;
-       err = fuse_fill_super_common(sb, &ctx);
+       ctx->fudptr = (void **)&fs->vqs[VQ_REQUEST].fud;
+       if (ctx->dax)
+               ctx->dax_dev = fs->dax_dev;
+       err = fuse_fill_super_common(sb, ctx);
        if (err < 0)
                goto err_free_fuse_devs;
 
@@ -1200,7 +1246,7 @@ 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;
@@ -1215,11 +1261,19 @@ 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;
 }
-- 
2.20.1

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