[PATCH 3/4] NOMMU: Generalise the handling of MTD-specific superblocks
From: David Howells
Date: Wed Feb 21 2007 - 07:58:10 EST
From: David Howells <dhowells@xxxxxxxxxx>
Generalise the handling of MTD-specific superblocks so that JFFS2 and ROMFS can
both share it.
Signed-Off-By: David Howells <dhowells@xxxxxxxxxx>
---
drivers/mtd/Makefile | 2
drivers/mtd/mtdsuper.c | 231 +++++++++++++++++++++++++++++++++++++++++++++
fs/jffs2/super.c | 194 ++++----------------------------------
include/linux/fs.h | 1
include/linux/mtd/super.h | 30 ++++++
5 files changed, 282 insertions(+), 176 deletions(-)
diff --git a/drivers/mtd/Makefile b/drivers/mtd/Makefile
index a75b82a..f9f0ffd 100644
--- a/drivers/mtd/Makefile
+++ b/drivers/mtd/Makefile
@@ -4,7 +4,7 @@
# $Id: Makefile.common,v 1.7 2005/07/11 10:39:27 gleixner Exp $
# Core functionality.
-mtd-y := mtdcore.o mtdbdi.o
+mtd-y := mtdcore.o mtdbdi.o mtdsuper.o
mtd-$(CONFIG_MTD_PARTITIONS) += mtdpart.o
obj-$(CONFIG_MTD) += $(mtd-y)
diff --git a/drivers/mtd/mtdsuper.c b/drivers/mtd/mtdsuper.c
new file mode 100644
index 0000000..7ffab96
--- /dev/null
+++ b/drivers/mtd/mtdsuper.c
@@ -0,0 +1,231 @@
+/* MTD-based superblock management
+ *
+ * Copyright (C) 2006 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@xxxxxxxxxx)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/mtd/super.h>
+#include <linux/namei.h>
+#include <linux/ctype.h>
+
+/*
+ * compare superblocks to see if they're equivalent
+ * - they are if the underlying MTD device is the same
+ */
+static int get_sb_mtd_compare(struct super_block *sb, void *_mtd)
+{
+ struct mtd_info *mtd = _mtd;
+
+ if (sb->s_mtd == mtd) {
+ DEBUG(2, "MTDSB: Match on device %d (\"%s\")\n",
+ mtd->index, mtd->name);
+ return 1;
+ }
+
+ DEBUG(2, "MTDSB: No match, device %d (\"%s\"), device %d (\"%s\")\n",
+ sb->s_mtd->index, sb->s_mtd->name, mtd->index, mtd->name);
+ return 0;
+}
+
+/*
+ * mark the superblock by the MTD device it is using
+ * - set the device number to be the correct MTD block device for pesuperstence
+ * of NFS exports
+ */
+static int get_sb_mtd_set(struct super_block *sb, void *_mtd)
+{
+ struct mtd_info *mtd = _mtd;
+
+ sb->s_mtd = mtd;
+ sb->s_dev = MKDEV(MTD_BLOCK_MAJOR, mtd->index);
+ return 0;
+}
+
+/*
+ * get a superblock on an MTD-backed filesystem
+ */
+static int get_sb_mtd_aux(struct file_system_type *fs_type, int flags,
+ const char *dev_name, void *data,
+ struct mtd_info *mtd,
+ int (*fill_super)(struct super_block *, void *, int),
+ struct vfsmount *mnt)
+{
+ struct super_block *sb;
+ int ret;
+
+ sb = sget(fs_type, get_sb_mtd_compare, get_sb_mtd_set, mtd);
+ if (IS_ERR(sb))
+ goto out_error;
+
+ if (sb->s_root)
+ goto already_mounted;
+
+ /* fresh new superblock */
+ DEBUG(1, "MTDSB: New superblock for device %d (\"%s\")\n",
+ mtd->index, mtd->name);
+
+ ret = fill_super(sb, data, flags & MS_SILENT ? 1 : 0);
+ if (ret < 0) {
+ up_write(&sb->s_umount);
+ deactivate_super(sb);
+ return ret;
+ }
+
+ /* go */
+ sb->s_flags |= MS_ACTIVE;
+ return simple_set_mnt(mnt, sb);
+
+ /* new mountpoint for an already mounted superblock */
+already_mounted:
+ DEBUG(1, "MTDSB: Device %d (\"%s\") is already mounted\n",
+ mtd->index, mtd->name);
+ ret = simple_set_mnt(mnt, sb);
+ goto out_put;
+
+out_error:
+ ret = PTR_ERR(sb);
+out_put:
+ put_mtd_device(mtd);
+ return ret;
+}
+
+/*
+ * get a superblock on an MTD-backed filesystem by MTD device number
+ */
+static int get_sb_mtd_nr(struct file_system_type *fs_type, int flags,
+ const char *dev_name, void *data, int mtdnr,
+ int (*fill_super)(struct super_block *, void *, int),
+ struct vfsmount *mnt)
+{
+ struct mtd_info *mtd;
+
+ mtd = get_mtd_device(NULL, mtdnr);
+ if (!mtd) {
+ DEBUG(0, "MTDSB: Device #%u doesn't appear to exist\n", mtdnr);
+ return -EINVAL;
+ }
+
+ return get_sb_mtd_aux(fs_type, flags, dev_name, data, mtd, fill_super,
+ mnt);
+}
+
+/*
+ * set up an MTD-based superblock
+ */
+int get_sb_mtd(struct file_system_type *fs_type, int flags,
+ const char *dev_name, void *data,
+ int (*fill_super)(struct super_block *, void *, int),
+ struct vfsmount *mnt)
+{
+ struct nameidata nd;
+ int mtdnr, ret;
+
+ if (!dev_name)
+ return -EINVAL;
+
+ DEBUG(2, "MTDSB: dev_name \"%s\"\n", dev_name);
+
+ /* the preferred way of mounting in future; especially when
+ * CONFIG_BLOCK=n - we specify the underlying MTD device by number or
+ * by name, so that we don't require block device support to be present
+ * in the kernel. */
+ if (dev_name[0] == 'm' && dev_name[1] == 't' && dev_name[2] == 'd') {
+ if (dev_name[3] == ':') {
+ struct mtd_info *mtd;
+
+ /* mount by MTD device name */
+ DEBUG(1, "MTDSB: mtd:%%s, name \"%s\"\n",
+ dev_name + 4);
+
+ for (mtdnr = 0; mtdnr < MAX_MTD_DEVICES; mtdnr++) {
+ mtd = get_mtd_device(NULL, mtdnr);
+ if (mtd) {
+ if (!strcmp(mtd->name, dev_name + 4))
+ return get_sb_mtd_aux(
+ fs_type, flags,
+ dev_name, data, mtd,
+ fill_super, mnt);
+
+ put_mtd_device(mtd);
+ }
+ }
+
+ printk(KERN_NOTICE "MTD:"
+ " MTD device with name \"%s\" not found.\n",
+ dev_name + 4);
+
+ } else if (isdigit(dev_name[3])) {
+ /* mount by MTD device number name */
+ char *endptr;
+
+ mtdnr = simple_strtoul(dev_name + 3, &endptr, 0);
+ if (!*endptr) {
+ /* It was a valid number */
+ DEBUG(1, "MTDSB: mtd%%d, mtdnr %d\n",
+ mtdnr);
+ return get_sb_mtd_nr(fs_type, flags,
+ dev_name, data,
+ mtdnr, fill_super, mnt);
+ }
+ }
+ }
+
+ /* try the old way - the hack where we allowed users to mount
+ * /dev/mtdblock$(n) but didn't actually _use_ the blockdev
+ */
+ ret = path_lookup(dev_name, LOOKUP_FOLLOW, &nd);
+
+ DEBUG(1, "MTDSB: path_lookup() returned %d, inode %p\n",
+ ret, nd.dentry ? nd.dentry->d_inode : NULL);
+
+ if (ret)
+ return ret;
+
+ ret = -EINVAL;
+
+ if (!S_ISBLK(nd.dentry->d_inode->i_mode))
+ goto out;
+
+ if (nd.mnt->mnt_flags & MNT_NODEV) {
+ ret = -EACCES;
+ goto out;
+ }
+
+ if (imajor(nd.dentry->d_inode) != MTD_BLOCK_MAJOR)
+ goto not_an_MTD_device;
+
+ mtdnr = iminor(nd.dentry->d_inode);
+ path_release(&nd);
+
+ return get_sb_mtd_nr(fs_type, flags, dev_name, data, mtdnr, fill_super,
+ mnt);
+
+not_an_MTD_device:
+ if (!(flags & MS_SILENT))
+ printk(KERN_NOTICE
+ "MTD: Attempt to mount non-MTD device \"%s\"\n",
+ dev_name);
+out:
+ path_release(&nd);
+ return ret;
+
+}
+
+EXPORT_SYMBOL_GPL(get_sb_mtd);
+
+/*
+ * destroy an MTD-based superblock
+ */
+void kill_mtd_super(struct super_block *sb)
+{
+ generic_shutdown_super(sb);
+ put_mtd_device(sb->s_mtd);
+ sb->s_mtd = NULL;
+}
+
+EXPORT_SYMBOL_GPL(kill_mtd_super);
diff --git a/fs/jffs2/super.c b/fs/jffs2/super.c
index cc7e8e7..f5e4068 100644
--- a/fs/jffs2/super.c
+++ b/fs/jffs2/super.c
@@ -21,7 +21,7 @@
#include <linux/mount.h>
#include <linux/jffs2.h>
#include <linux/pagemap.h>
-#include <linux/mtd/mtd.h>
+#include <linux/mtd/super.h>
#include <linux/ctype.h>
#include <linux/namei.h>
#include "compr.h"
@@ -80,69 +80,27 @@ static const struct super_operations jffs2_super_operations =
.sync_fs = jffs2_sync_fs,
};
-static int jffs2_sb_compare(struct super_block *sb, void *data)
-{
- struct jffs2_sb_info *p = data;
- struct jffs2_sb_info *c = JFFS2_SB_INFO(sb);
-
- /* The superblocks are considered to be equivalent if the underlying MTD
- device is the same one */
- if (c->mtd == p->mtd) {
- D1(printk(KERN_DEBUG "jffs2_sb_compare: match on device %d (\"%s\")\n", p->mtd->index, p->mtd->name));
- return 1;
- } else {
- D1(printk(KERN_DEBUG "jffs2_sb_compare: No match, device %d (\"%s\"), device %d (\"%s\")\n",
- c->mtd->index, c->mtd->name, p->mtd->index, p->mtd->name));
- return 0;
- }
-}
-
-static int jffs2_sb_set(struct super_block *sb, void *data)
-{
- struct jffs2_sb_info *p = data;
-
- /* For persistence of NFS exports etc. we use the same s_dev
- each time we mount the device, don't just use an anonymous
- device */
- sb->s_fs_info = p;
- p->os_priv = sb;
- sb->s_dev = MKDEV(MTD_BLOCK_MAJOR, p->mtd->index);
-
- return 0;
-}
-
-static int jffs2_get_sb_mtd(struct file_system_type *fs_type,
- int flags, const char *dev_name,
- void *data, struct mtd_info *mtd,
- struct vfsmount *mnt)
+/*
+ * fill in the superblock
+ */
+static int jffs2_fill_super(struct super_block *sb, void *data, int silent)
{
- struct super_block *sb;
struct jffs2_sb_info *c;
- int ret;
+
+ D1(printk(KERN_DEBUG "jffs2_get_sb_mtd():"
+ " New superblock for device %d (\"%s\")\n",
+ sb->s_mtd->index, sb->s_mtd->name));
c = kzalloc(sizeof(*c), GFP_KERNEL);
if (!c)
return -ENOMEM;
- c->mtd = mtd;
-
- sb = sget(fs_type, jffs2_sb_compare, jffs2_sb_set, c);
-
- if (IS_ERR(sb))
- goto out_error;
-
- if (sb->s_root) {
- /* New mountpoint for JFFS2 which is already mounted */
- D1(printk(KERN_DEBUG "jffs2_get_sb_mtd(): Device %d (\"%s\") is already mounted\n",
- mtd->index, mtd->name));
- ret = simple_set_mnt(mnt, sb);
- goto out_put;
- }
- D1(printk(KERN_DEBUG "jffs2_get_sb_mtd(): New superblock for device %d (\"%s\")\n",
- mtd->index, mtd->name));
+ c->mtd = sb->s_mtd;
+ c->os_priv = sb;
+ sb->s_fs_info = c;
- /* Initialize JFFS2 superblock locks, the further initialization will be
- * done later */
+ /* Initialize JFFS2 superblock locks, the further initialization will
+ * be done later */
init_MUTEX(&c->alloc_sem);
init_MUTEX(&c->erase_free_sem);
init_waitqueue_head(&c->erase_wait);
@@ -151,133 +109,20 @@ static int jffs2_get_sb_mtd(struct file_system_type *fs_type,
spin_lock_init(&c->inocache_lock);
sb->s_op = &jffs2_super_operations;
- sb->s_flags = flags | MS_NOATIME;
+ sb->s_flags = sb->s_flags | MS_NOATIME;
sb->s_xattr = jffs2_xattr_handlers;
#ifdef CONFIG_JFFS2_FS_POSIX_ACL
sb->s_flags |= MS_POSIXACL;
#endif
- ret = jffs2_do_fill_super(sb, data, flags & MS_SILENT ? 1 : 0);
-
- if (ret) {
- /* Failure case... */
- up_write(&sb->s_umount);
- deactivate_super(sb);
- return ret;
- }
-
- sb->s_flags |= MS_ACTIVE;
- return simple_set_mnt(mnt, sb);
-
-out_error:
- ret = PTR_ERR(sb);
- out_put:
- kfree(c);
- put_mtd_device(mtd);
-
- return ret;
-}
-
-static int jffs2_get_sb_mtdnr(struct file_system_type *fs_type,
- int flags, const char *dev_name,
- void *data, int mtdnr,
- struct vfsmount *mnt)
-{
- struct mtd_info *mtd;
-
- mtd = get_mtd_device(NULL, mtdnr);
- if (IS_ERR(mtd)) {
- D1(printk(KERN_DEBUG "jffs2: MTD device #%u doesn't appear to exist\n", mtdnr));
- return PTR_ERR(mtd);
- }
-
- return jffs2_get_sb_mtd(fs_type, flags, dev_name, data, mtd, mnt);
+ return jffs2_do_fill_super(sb, data, silent);
}
static int jffs2_get_sb(struct file_system_type *fs_type,
int flags, const char *dev_name,
void *data, struct vfsmount *mnt)
{
- int err;
- struct nameidata nd;
- int mtdnr;
-
- if (!dev_name)
- return -EINVAL;
-
- D1(printk(KERN_DEBUG "jffs2_get_sb(): dev_name \"%s\"\n", dev_name));
-
- /* The preferred way of mounting in future; especially when
- CONFIG_BLK_DEV is implemented - we specify the underlying
- MTD device by number or by name, so that we don't require
- block device support to be present in the kernel. */
-
- /* FIXME: How to do the root fs this way? */
-
- if (dev_name[0] == 'm' && dev_name[1] == 't' && dev_name[2] == 'd') {
- /* Probably mounting without the blkdev crap */
- if (dev_name[3] == ':') {
- struct mtd_info *mtd;
-
- /* Mount by MTD device name */
- D1(printk(KERN_DEBUG "jffs2_get_sb(): mtd:%%s, name \"%s\"\n", dev_name+4));
- for (mtdnr = 0; mtdnr < MAX_MTD_DEVICES; mtdnr++) {
- mtd = get_mtd_device(NULL, mtdnr);
- if (!IS_ERR(mtd)) {
- if (!strcmp(mtd->name, dev_name+4))
- return jffs2_get_sb_mtd(fs_type, flags, dev_name, data, mtd, mnt);
- put_mtd_device(mtd);
- }
- }
- printk(KERN_NOTICE "jffs2_get_sb(): MTD device with name \"%s\" not found.\n", dev_name+4);
- } else if (isdigit(dev_name[3])) {
- /* Mount by MTD device number name */
- char *endptr;
-
- mtdnr = simple_strtoul(dev_name+3, &endptr, 0);
- if (!*endptr) {
- /* It was a valid number */
- D1(printk(KERN_DEBUG "jffs2_get_sb(): mtd%%d, mtdnr %d\n", mtdnr));
- return jffs2_get_sb_mtdnr(fs_type, flags, dev_name, data, mtdnr, mnt);
- }
- }
- }
-
- /* Try the old way - the hack where we allowed users to mount
- /dev/mtdblock$(n) but didn't actually _use_ the blkdev */
-
- err = path_lookup(dev_name, LOOKUP_FOLLOW, &nd);
-
- D1(printk(KERN_DEBUG "jffs2_get_sb(): path_lookup() returned %d, inode %p\n",
- err, nd.dentry->d_inode));
-
- if (err)
- return err;
-
- err = -EINVAL;
-
- if (!S_ISBLK(nd.dentry->d_inode->i_mode))
- goto out;
-
- if (nd.mnt->mnt_flags & MNT_NODEV) {
- err = -EACCES;
- goto out;
- }
-
- if (imajor(nd.dentry->d_inode) != MTD_BLOCK_MAJOR) {
- if (!(flags & MS_SILENT))
- printk(KERN_NOTICE "Attempt to mount non-MTD device \"%s\" as JFFS2\n",
- dev_name);
- goto out;
- }
-
- mtdnr = iminor(nd.dentry->d_inode);
- path_release(&nd);
-
- return jffs2_get_sb_mtdnr(fs_type, flags, dev_name, data, mtdnr, mnt);
-
-out:
- path_release(&nd);
- return err;
+ return get_sb_mtd(fs_type, flags, dev_name, data, jffs2_fill_super,
+ mnt);
}
static void jffs2_put_super (struct super_block *sb)
@@ -312,8 +157,7 @@ static void jffs2_kill_sb(struct super_block *sb)
struct jffs2_sb_info *c = JFFS2_SB_INFO(sb);
if (!(sb->s_flags & MS_RDONLY))
jffs2_stop_garbage_collect_thread(c);
- generic_shutdown_super(sb);
- put_mtd_device(c->mtd);
+ kill_mtd_super(sb);
kfree(c);
}
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 86ec3f4..1b589f2 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -932,6 +932,7 @@ struct super_block {
struct list_head s_files;
struct block_device *s_bdev;
+ struct mtd_info *s_mtd;
struct list_head s_instances;
struct quota_info s_dquot; /* Diskquota specific options */
diff --git a/include/linux/mtd/super.h b/include/linux/mtd/super.h
new file mode 100644
index 0000000..8fcdbdf
--- /dev/null
+++ b/include/linux/mtd/super.h
@@ -0,0 +1,30 @@
+/* MTD-based superblock handling
+ *
+ * Copyright (C) 2006 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@xxxxxxxxxx)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#ifndef __MTD_SUPER_H__
+#define __MTD_SUPER_H__
+
+#ifdef __KERNEL__
+
+#include <linux/mtd/mtd.h>
+#include <linux/fs.h>
+#include <linux/mount.h>
+
+extern int get_sb_mtd(struct file_system_type *fs_type, int flags,
+ const char *dev_name, void *data,
+ int (*fill_super)(struct super_block *, void *, int),
+ struct vfsmount *mnt);
+extern void kill_mtd_super(struct super_block *sb);
+
+
+#endif /* __KERNEL__ */
+
+#endif /* __MTD_SUPER_H__ */
-
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