Message-ID: <155317581590.13185.6486189707405250496.stgit@warthog.procyon.org.uk>
Date:   Thu, 21 Mar 2019 13:43:35 +0000
From:   David Howells <dhowells@...hat.com>
To:     jaharkes@...cmu.edu
Cc:     coda@...cmu.edu, dhowells@...hat.com,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] vfs: Convert coda to fs_context

Convert coda to fs_context.  Note this is slightly tricky as coda currently
only has a binary mount data interface.  This is handled through the
parse_monolithic hook.

Also add a more conventional interface with a parameter named "fd" that
takes an fd that refers to a coda psdev, thereby specifying the index to
use.

Signed-off-by: David Howells <dhowells@...hat.com>
cc: Jan Harkes <jaharkes@...cmu.edu>
cc: coda@...cmu.edu
---

 fs/coda/inode.c |  171 +++++++++++++++++++++++++++++++++++++------------------
 1 file changed, 116 insertions(+), 55 deletions(-)

diff --git a/fs/coda/inode.c b/fs/coda/inode.c
index 97424cf206c0..aaed68ba960b 100644
--- a/fs/coda/inode.c
+++ b/fs/coda/inode.c
@@ -2,9 +2,9 @@
 /*
  * Super block/filesystem wide operations
  *
- * Copyright (C) 1996 Peter J. Braam <braam@...hs.ox.ac.uk> and 
- * Michael Callahan <callahan@...hs.ox.ac.uk> 
- * 
+ * Copyright (C) 1996 Peter J. Braam <braam@...hs.ox.ac.uk> and
+ * Michael Callahan <callahan@...hs.ox.ac.uk>
+ *
  * Rewritten for Linux 2.1.  Peter Braam <braam@...cmu.edu>
  * Copyright (C) Carnegie Mellon University
  */
@@ -24,6 +24,8 @@
 #include <linux/pid_namespace.h>
 #include <linux/uaccess.h>
 #include <linux/fs.h>
+#include <linux/fs_context.h>
+#include <linux/fs_parser.h>
 #include <linux/vmalloc.h>
 
 #include <linux/coda.h>
@@ -93,10 +95,10 @@ void coda_destroy_inodecache(void)
 	kmem_cache_destroy(coda_inode_cachep);
 }
 
-static int coda_remount(struct super_block *sb, int *flags, char *data)
+static int coda_reconfigure(struct fs_context *fc)
 {
-	sync_filesystem(sb);
-	*flags |= SB_NOATIME;
+	sync_filesystem(fc->root->d_sb);
+	fc->sb_flags |= SB_NOATIME;
 	return 0;
 }
 
@@ -108,78 +110,111 @@ static const struct super_operations coda_super_operations =
 	.evict_inode	= coda_evict_inode,
 	.put_super	= coda_put_super,
 	.statfs		= coda_statfs,
-	.remount_fs	= coda_remount,
 };
 
-static int get_device_index(struct coda_mount_data *data)
+struct coda_fs_context {
+	int	idx;
+};
+
+enum {
+	Opt_fd,
+};
+
+static const struct fs_parameter_spec coda_param_specs[] = {
+	fsparam_fd	("fd",				Opt_fd),
+	{}
+};
+
+static const struct fs_parameter_description coda_fs_parameters = {
+	.name		= "coda",
+	.specs		= coda_param_specs,
+};
+
+static int coda_parse_fd(struct fs_context *fc, int fd)
 {
+	struct coda_fs_context *ctx = fc->fs_private;
 	struct fd f;
 	struct inode *inode;
 	int idx;
 
-	if (data == NULL) {
-		pr_warn("%s: Bad mount data\n", __func__);
-		return -1;
-	}
-
-	if (data->version != CODA_MOUNT_VERSION) {
-		pr_warn("%s: Bad mount version\n", __func__);
-		return -1;
-	}
-
-	f = fdget(data->fd);
+	f = fdget(fd);
 	if (!f.file)
-		goto Ebadf;
+		return -EBADF;
+
 	inode = file_inode(f.file);
 	if (!S_ISCHR(inode->i_mode) || imajor(inode) != CODA_PSDEV_MAJOR) {
 		fdput(f);
-		goto Ebadf;
+		return invalf(fc, "code: Not coda psdev");
 	}
 
 	idx = iminor(inode);
 	fdput(f);
 
-	if (idx < 0 || idx >= MAX_CODADEVS) {
-		pr_warn("%s: Bad minor number\n", __func__);
-		return -1;
+	if (idx < 0 || idx >= MAX_CODADEVS)
+		return invalf(fc, "coda: Bad minor number");
+	ctx->idx = idx;
+	return 0;
+}
+
+static int coda_parse_param(struct fs_context *fc, struct fs_parameter *param)
+{
+	struct fs_parse_result result;
+	int opt;
+
+	opt = fs_parse(fc, &coda_fs_parameters, param, &result);
+	if (opt < 0)
+		return opt;
+
+	switch (opt) {
+	case Opt_fd:
+		return coda_parse_fd(fc, result.uint_32);
+	}
+
+	return 0;
+}
+
+/*
+ * Parse coda's binary mount data form.  We ignore any errors and go with index
+ * 0 if we get one for backward compatibility.
+ */
+static int coda_parse_monolithic(struct fs_context *fc, void *_data)
+{
+	struct coda_mount_data *data = _data;
+
+	if (!data) {
+		invalf(fc, "coda: Bad mount data");
+		return 0;
+	}
+	if (data->version != CODA_MOUNT_VERSION) {
+		invalf(fc, "coda: Bad mount version");
+		return 0;
 	}
 
-	return idx;
-Ebadf:
-	pr_warn("%s: Bad file\n", __func__);
-	return -1;
+	coda_parse_fd(fc, data->fd);
+	return 0;
 }
 
-static int coda_fill_super(struct super_block *sb, void *data, int silent)
+static int coda_fill_super(struct super_block *sb, struct fs_context *fc)
 {
+	struct coda_fs_context *ctx = fc->fs_private;
 	struct inode *root = NULL;
 	struct venus_comm *vc;
 	struct CodaFid fid;
 	int error;
-	int idx;
 
-	if (task_active_pid_ns(current) != &init_pid_ns)
-		return -EINVAL;
+	infof(fc, "coda: device index: %i\n", ctx->idx);
 
-	idx = get_device_index((struct coda_mount_data *) data);
-
-	/* Ignore errors in data, for backward compatibility */
-	if(idx == -1)
-		idx = 0;
-	
-	pr_info("%s: device index: %i\n", __func__,  idx);
-
-	vc = &coda_comms[idx];
+	vc = &coda_comms[ctx->idx];
 	mutex_lock(&vc->vc_mutex);
 
 	if (!vc->vc_inuse) {
-		pr_warn("%s: No pseudo device\n", __func__);
+		errorf(fc, "coda: No pseudo device");
 		error = -EINVAL;
 		goto unlock_out;
 	}
 
 	if (vc->vc_sb) {
-		pr_warn("%s: Device already mounted\n", __func__);
+		errorf(fc, "coda: Device already mounted");
 		error = -EBUSY;
 		goto unlock_out;
 	}
@@ -207,7 +242,7 @@ static int coda_fill_super(struct super_block *sb, void *data, int silent)
 		goto error;
 	}
 	pr_info("%s: rootfid is %s\n", __func__, coda_f2s(&fid));
-	
+
 	/* make root inode */
         root = coda_cnode_make(&fid, sb);
         if (IS_ERR(root)) {
@@ -215,7 +250,7 @@ static int coda_fill_super(struct super_block *sb, void *data, int silent)
 		pr_warn("Failure of coda_cnode_make for root: error %d\n",
 			error);
 		goto error;
-	} 
+	}
 
 	pr_info("%s: rootinode is %ld dev %s\n",
 		__func__, root->i_ino, root->i_sb->s_id);
@@ -268,7 +303,7 @@ int coda_setattr(struct dentry *de, struct iattr *iattr)
 	struct coda_vattr vattr;
 	int error;
 
-	memset(&vattr, 0, sizeof(vattr)); 
+	memset(&vattr, 0, sizeof(vattr));
 
 	inode->i_ctime = current_time(inode);
 	coda_iattr_to_vattr(iattr, &vattr);
@@ -278,7 +313,7 @@ int coda_setattr(struct dentry *de, struct iattr *iattr)
 	error = venus_setattr(inode->i_sb, coda_i2f(inode), &vattr);
 
 	if (!error) {
-	        coda_vattr_to_iattr(inode, &vattr); 
+	        coda_vattr_to_iattr(inode, &vattr);
 		coda_cache_clear_inode(inode);
 	}
 	return error;
@@ -293,7 +328,7 @@ const struct inode_operations coda_file_inode_operations = {
 static int coda_statfs(struct dentry *dentry, struct kstatfs *buf)
 {
 	int error;
-	
+
 	error = venus_statfs(dentry, buf);
 
 	if (error) {
@@ -310,23 +345,49 @@ static int coda_statfs(struct dentry *dentry, struct kstatfs *buf)
 	buf->f_bsize = 4096;
 	buf->f_namelen = CODA_MAXNAMLEN;
 
-	return 0; 
+	return 0;
 }
 
-/* init_coda: used by filesystems.c to register coda */
+static int coda_get_tree(struct fs_context *fc)
+{
+	if (task_active_pid_ns(current) != &init_pid_ns)
+		return -EINVAL;
+
+	return vfs_get_super(fc, vfs_get_independent_super, coda_fill_super);
+}
+
+static void coda_free_fc(struct fs_context *fc)
+{
+	kfree(fc->fs_private);
+}
 
-static struct dentry *coda_mount(struct file_system_type *fs_type,
-	int flags, const char *dev_name, void *data)
+static const struct fs_context_operations coda_context_ops = {
+	.free		= coda_free_fc,
+	.parse_param	= coda_parse_param,
+	.parse_monolithic = coda_parse_monolithic,
+	.get_tree	= coda_get_tree,
+	.reconfigure	= coda_reconfigure,
+};
+
+static int coda_init_fs_context(struct fs_context *fc)
 {
-	return mount_nodev(fs_type, flags, data, coda_fill_super);
+	struct coda_fs_context *ctx;
+
+	ctx = kzalloc(sizeof(struct coda_fs_context), GFP_KERNEL);
+	if (!ctx)
+		return -ENOMEM;
+
+	fc->fs_private = ctx;
+	fc->ops = &coda_context_ops;
+	return 0;
 }
 
 struct file_system_type coda_fs_type = {
 	.owner		= THIS_MODULE,
 	.name		= "coda",
-	.mount		= coda_mount,
+	.init_fs_context = coda_init_fs_context,
+	.parameters	= &coda_fs_parameters,
 	.kill_sb	= kill_anon_super,
 	.fs_flags	= FS_BINARY_MOUNTDATA,
 };
 MODULE_ALIAS_FS("coda");
-

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