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

[John Groves <John@xxxxxxxxxx>]

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

Signed-off-by: John Groves <john@xxxxxxxxxx>
---
 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