[RFC V2 11/18] famfs_fuse: Basic famfs mount opts

[John Groves]

* -o shadow=<shadowpath>
* -o daxdev=<daxdev>

Signed-off-by: John Groves <j...@groves.net>
---
 fs/fuse/fuse_i.h |  8 +++++++-
 fs/fuse/inode.c  | 28 +++++++++++++++++++++++++++-
 2 files changed, 34 insertions(+), 2 deletions(-)

diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index a592c1002861..f4ee61046578 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -583,9 +583,11 @@ struct fuse_fs_context {
        unsigned int blksize;
        const char *subtype;
 
-       /* DAX device, may be NULL */
+       /* DAX device for virtiofs, may be NULL */
        struct dax_device *dax_dev;
 
+       const char *shadow; /* famfs - null if not famfs */
+
        /* fuse_dev pointer to fill in, should contain NULL on entry */
        void **fudptr;
 };
@@ -941,6 +943,10 @@ struct fuse_conn {
        /**  uring connection information*/
        struct fuse_ring *ring;
 #endif
+
+#if IS_ENABLED(CONFIG_FUSE_FAMFS_DAX)
+       char *shadow;
+#endif
 };
 
 /*
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index e48e11c3f9f3..a7e1cf8257b0 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -766,6 +766,9 @@ enum {
        OPT_ALLOW_OTHER,
        OPT_MAX_READ,
        OPT_BLKSIZE,
+#if IS_ENABLED(CONFIG_FUSE_FAMFS_DAX)
+       OPT_SHADOW,
+#endif
        OPT_ERR
 };
 
@@ -780,6 +783,9 @@ static const struct fs_parameter_spec fuse_fs_parameters[] 
= {
        fsparam_u32     ("max_read",            OPT_MAX_READ),
        fsparam_u32     ("blksize",             OPT_BLKSIZE),
        fsparam_string  ("subtype",             OPT_SUBTYPE),
+#if IS_ENABLED(CONFIG_FUSE_FAMFS_DAX)
+       fsparam_string("shadow",                OPT_SHADOW),
+#endif
        {}
 };
 
@@ -875,6 +881,15 @@ static int fuse_parse_param(struct fs_context *fsc, struct 
fs_parameter *param)
                ctx->blksize = result.uint_32;
                break;
 
+#if IS_ENABLED(CONFIG_FUSE_FAMFS_DAX)
+       case OPT_SHADOW:
+               if (ctx->shadow)
+                       return invalfc(fsc, "Multiple shadows specified");
+               ctx->shadow = param->string;
+               param->string = NULL;
+               break;
+#endif
+
        default:
                return -EINVAL;
        }
@@ -888,6 +903,7 @@ static void fuse_free_fsc(struct fs_context *fsc)
 
        if (ctx) {
                kfree(ctx->subtype);
+               kfree(ctx->shadow);
                kfree(ctx);
        }
 }
@@ -919,7 +935,10 @@ static int fuse_show_options(struct seq_file *m, struct 
dentry *root)
        else if (fc->dax_mode == FUSE_DAX_INODE_USER)
                seq_puts(m, ",dax=inode");
 #endif
-
+#if IS_ENABLED(CONFIG_FUSE_FAMFS_DAX)
+       if (fc->shadow)
+               seq_printf(m, ",shadow=%s", fc->shadow);
+#endif
        return 0;
 }
 
@@ -1017,6 +1036,9 @@ void fuse_conn_put(struct fuse_conn *fc)
                }
                if (IS_ENABLED(CONFIG_FUSE_PASSTHROUGH))
                        fuse_backing_files_free(fc);
+#if IS_ENABLED(CONFIG_FUSE_FAMFS_DAX)
+               kfree(fc->shadow);
+#endif
                call_rcu(&fc->rcu, delayed_release);
        }
 }
@@ -1834,6 +1856,10 @@ int fuse_fill_super_common(struct super_block *sb, 
struct fuse_fs_context *ctx)
        sb->s_root = root_dentry;
        if (ctx->fudptr)
                *ctx->fudptr = fud;
+
+#if IS_ENABLED(CONFIG_FUSE_FAMFS_DAX)
+       fc->shadow = kstrdup(ctx->shadow, GFP_KERNEL);
+#endif
        mutex_unlock(&fuse_mutex);
        return 0;
 
-- 
2.49.0