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/drivers/mtd/mtdsuper.c

https://bitbucket.org/ndreys/linux-sunxi
C | 220 lines | 136 code | 37 blank | 47 comment | 23 complexity | ae34703c99b2189dfaa91c3577fa4a40 MD5 | raw file
Possible License(s): GPL-2.0, LGPL-2.0, AGPL-1.0
  1/* MTD-based superblock management
  2 *
  3 * Copyright � 2001-2007 Red Hat, Inc. All Rights Reserved.
  4 * Copyright � 2001-2010 David Woodhouse <dwmw2@infradead.org>
  5 *
  6 * Written by:  David Howells <dhowells@redhat.com>
  7 *              David Woodhouse <dwmw2@infradead.org>
  8 *
  9 * This program is free software; you can redistribute it and/or
 10 * modify it under the terms of the GNU General Public License
 11 * as published by the Free Software Foundation; either version
 12 * 2 of the License, or (at your option) any later version.
 13 */
 14
 15#include <linux/mtd/super.h>
 16#include <linux/namei.h>
 17#include <linux/ctype.h>
 18#include <linux/slab.h>
 19
 20/*
 21 * compare superblocks to see if they're equivalent
 22 * - they are if the underlying MTD device is the same
 23 */
 24static int get_sb_mtd_compare(struct super_block *sb, void *_mtd)
 25{
 26	struct mtd_info *mtd = _mtd;
 27
 28	if (sb->s_mtd == mtd) {
 29		DEBUG(2, "MTDSB: Match on device %d (\"%s\")\n",
 30		      mtd->index, mtd->name);
 31		return 1;
 32	}
 33
 34	DEBUG(2, "MTDSB: No match, device %d (\"%s\"), device %d (\"%s\")\n",
 35	      sb->s_mtd->index, sb->s_mtd->name, mtd->index, mtd->name);
 36	return 0;
 37}
 38
 39/*
 40 * mark the superblock by the MTD device it is using
 41 * - set the device number to be the correct MTD block device for pesuperstence
 42 *   of NFS exports
 43 */
 44static int get_sb_mtd_set(struct super_block *sb, void *_mtd)
 45{
 46	struct mtd_info *mtd = _mtd;
 47
 48	sb->s_mtd = mtd;
 49	sb->s_dev = MKDEV(MTD_BLOCK_MAJOR, mtd->index);
 50	sb->s_bdi = mtd->backing_dev_info;
 51	return 0;
 52}
 53
 54/*
 55 * get a superblock on an MTD-backed filesystem
 56 */
 57static struct dentry *mount_mtd_aux(struct file_system_type *fs_type, int flags,
 58			  const char *dev_name, void *data,
 59			  struct mtd_info *mtd,
 60			  int (*fill_super)(struct super_block *, void *, int))
 61{
 62	struct super_block *sb;
 63	int ret;
 64
 65	sb = sget(fs_type, get_sb_mtd_compare, get_sb_mtd_set, mtd);
 66	if (IS_ERR(sb))
 67		goto out_error;
 68
 69	if (sb->s_root)
 70		goto already_mounted;
 71
 72	/* fresh new superblock */
 73	DEBUG(1, "MTDSB: New superblock for device %d (\"%s\")\n",
 74	      mtd->index, mtd->name);
 75
 76	sb->s_flags = flags;
 77
 78	ret = fill_super(sb, data, flags & MS_SILENT ? 1 : 0);
 79	if (ret < 0) {
 80		deactivate_locked_super(sb);
 81		return ERR_PTR(ret);
 82	}
 83
 84	/* go */
 85	sb->s_flags |= MS_ACTIVE;
 86	return dget(sb->s_root);
 87
 88	/* new mountpoint for an already mounted superblock */
 89already_mounted:
 90	DEBUG(1, "MTDSB: Device %d (\"%s\") is already mounted\n",
 91	      mtd->index, mtd->name);
 92	put_mtd_device(mtd);
 93	return dget(sb->s_root);
 94
 95out_error:
 96	put_mtd_device(mtd);
 97	return ERR_CAST(sb);
 98}
 99
100/*
101 * get a superblock on an MTD-backed filesystem by MTD device number
102 */
103static struct dentry *mount_mtd_nr(struct file_system_type *fs_type, int flags,
104			 const char *dev_name, void *data, int mtdnr,
105			 int (*fill_super)(struct super_block *, void *, int))
106{
107	struct mtd_info *mtd;
108
109	mtd = get_mtd_device(NULL, mtdnr);
110	if (IS_ERR(mtd)) {
111		DEBUG(0, "MTDSB: Device #%u doesn't appear to exist\n", mtdnr);
112		return ERR_CAST(mtd);
113	}
114
115	return mount_mtd_aux(fs_type, flags, dev_name, data, mtd, fill_super);
116}
117
118/*
119 * set up an MTD-based superblock
120 */
121struct dentry *mount_mtd(struct file_system_type *fs_type, int flags,
122	       const char *dev_name, void *data,
123	       int (*fill_super)(struct super_block *, void *, int))
124{
125#ifdef CONFIG_BLOCK
126	struct block_device *bdev;
127	int ret, major;
128#endif
129	int mtdnr;
130
131	if (!dev_name)
132		return ERR_PTR(-EINVAL);
133
134	DEBUG(2, "MTDSB: dev_name \"%s\"\n", dev_name);
135
136	/* the preferred way of mounting in future; especially when
137	 * CONFIG_BLOCK=n - we specify the underlying MTD device by number or
138	 * by name, so that we don't require block device support to be present
139	 * in the kernel. */
140	if (dev_name[0] == 'm' && dev_name[1] == 't' && dev_name[2] == 'd') {
141		if (dev_name[3] == ':') {
142			struct mtd_info *mtd;
143
144			/* mount by MTD device name */
145			DEBUG(1, "MTDSB: mtd:%%s, name \"%s\"\n",
146			      dev_name + 4);
147
148			mtd = get_mtd_device_nm(dev_name + 4);
149			if (!IS_ERR(mtd))
150				return mount_mtd_aux(
151					fs_type, flags,
152					dev_name, data, mtd,
153					fill_super);
154
155			printk(KERN_NOTICE "MTD:"
156			       " MTD device with name \"%s\" not found.\n",
157			       dev_name + 4);
158
159		} else if (isdigit(dev_name[3])) {
160			/* mount by MTD device number name */
161			char *endptr;
162
163			mtdnr = simple_strtoul(dev_name + 3, &endptr, 0);
164			if (!*endptr) {
165				/* It was a valid number */
166				DEBUG(1, "MTDSB: mtd%%d, mtdnr %d\n",
167				      mtdnr);
168				return mount_mtd_nr(fs_type, flags,
169						     dev_name, data,
170						     mtdnr, fill_super);
171			}
172		}
173	}
174
175#ifdef CONFIG_BLOCK
176	/* try the old way - the hack where we allowed users to mount
177	 * /dev/mtdblock$(n) but didn't actually _use_ the blockdev
178	 */
179	bdev = lookup_bdev(dev_name);
180	if (IS_ERR(bdev)) {
181		ret = PTR_ERR(bdev);
182		DEBUG(1, "MTDSB: lookup_bdev() returned %d\n", ret);
183		return ERR_PTR(ret);
184	}
185	DEBUG(1, "MTDSB: lookup_bdev() returned 0\n");
186
187	ret = -EINVAL;
188
189	major = MAJOR(bdev->bd_dev);
190	mtdnr = MINOR(bdev->bd_dev);
191	bdput(bdev);
192
193	if (major != MTD_BLOCK_MAJOR)
194		goto not_an_MTD_device;
195
196	return mount_mtd_nr(fs_type, flags, dev_name, data, mtdnr, fill_super);
197
198not_an_MTD_device:
199#endif /* CONFIG_BLOCK */
200
201	if (!(flags & MS_SILENT))
202		printk(KERN_NOTICE
203		       "MTD: Attempt to mount non-MTD device \"%s\"\n",
204		       dev_name);
205	return ERR_PTR(-EINVAL);
206}
207
208EXPORT_SYMBOL_GPL(mount_mtd);
209
210/*
211 * destroy an MTD-based superblock
212 */
213void kill_mtd_super(struct super_block *sb)
214{
215	generic_shutdown_super(sb);
216	put_mtd_device(sb->s_mtd);
217	sb->s_mtd = NULL;
218}
219
220EXPORT_SYMBOL_GPL(kill_mtd_super);