linux-kernel - [RFC PATCH 11/19] famfs_fuse: Basic famfs mount opts

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Message-Id: <20250421013346.32530-12-john@groves.net>
Date: Sun, 20 Apr 2025 20:33:38 -0500
From: John Groves <John@...ves.net>
To: John Groves <John@...ves.net>,
	Dan Williams <dan.j.williams@...el.com>,
	Miklos Szeredi <miklos@...redb.hu>,
	Bernd Schubert <bschubert@....com>
Cc: John Groves <jgroves@...ron.com>,
	Jonathan Corbet <corbet@....net>,
	Vishal Verma <vishal.l.verma@...el.com>,
	Dave Jiang <dave.jiang@...el.com>,
	Matthew Wilcox <willy@...radead.org>,
	Jan Kara <jack@...e.cz>,
	Alexander Viro <viro@...iv.linux.org.uk>,
	Christian Brauner <brauner@...nel.org>,
	"Darrick J . Wong" <djwong@...nel.org>,
	Luis Henriques <luis@...lia.com>,
	Randy Dunlap <rdunlap@...radead.org>,
	Jeff Layton <jlayton@...nel.org>,
	Kent Overstreet <kent.overstreet@...ux.dev>,
	Petr Vorel <pvorel@...e.cz>,
	Brian Foster <bfoster@...hat.com>,
	linux-doc@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	nvdimm@...ts.linux.dev,
	linux-cxl@...r.kernel.org,
	linux-fsdevel@...r.kernel.org,
	Amir Goldstein <amir73il@...il.com>,
	Jonathan Cameron <Jonathan.Cameron@...wei.com>,
	Stefan Hajnoczi <shajnocz@...hat.com>,
	Joanne Koong <joannelkoong@...il.com>,
	Josef Bacik <josef@...icpanda.com>,
	Aravind Ramesh <arramesh@...ron.com>,
	Ajay Joshi <ajayjoshi@...ron.com>,
	John Groves <john@...ves.net>
Subject: [RFC PATCH 11/19] famfs_fuse: Basic famfs mount opts

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

Signed-off-by: John Groves <john@...ves.net>
---
 fs/fuse/fuse_i.h |  8 +++++++-
 fs/fuse/inode.c  | 25 ++++++++++++++++++++++++-
 2 files changed, 31 insertions(+), 2 deletions(-)

diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index b2c563b1a1c8..931613102d32 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -580,9 +580,11 @@ 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;
 };
@@ -938,6 +940,10 @@ 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 5c6947b12503..7f4b73e739cb 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;
 }
 
@@ -1825,6 +1844,10 @@ 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