12874c5fdSThomas Gleixner // SPDX-License-Identifier: GPL-2.0-or-later 2acaebfd8SDavid Howells /* MTD-based superblock management 3acaebfd8SDavid Howells * 4acaebfd8SDavid Howells * Copyright © 2001-2007 Red Hat, Inc. All Rights Reserved. 5a1452a37SDavid Woodhouse * Copyright © 2001-2010 David Woodhouse <dwmw2@infradead.org> 6a1452a37SDavid Woodhouse * 7acaebfd8SDavid Howells * Written by: David Howells <dhowells@redhat.com> 8acaebfd8SDavid Howells * David Woodhouse <dwmw2@infradead.org> 9acaebfd8SDavid Howells */ 10acaebfd8SDavid Howells 11acaebfd8SDavid Howells #include <linux/mtd/super.h> 12acaebfd8SDavid Howells #include <linux/namei.h> 13f3bcc017SPaul Gortmaker #include <linux/export.h> 14acaebfd8SDavid Howells #include <linux/ctype.h> 156de94002SJörn Engel #include <linux/slab.h> 16f83c3838SEzequiel Garcia #include <linux/major.h> 17fa06052dSJan Kara #include <linux/backing-dev.h> 18*ccdf7741SChristoph Hellwig #include <linux/blkdev.h> 190f071004SDavid Howells #include <linux/fs_context.h> 200f071004SDavid Howells #include "mtdcore.h" 210f071004SDavid Howells 220f071004SDavid Howells /* 230f071004SDavid Howells * compare superblocks to see if they're equivalent 240f071004SDavid Howells * - they are if the underlying MTD device is the same 250f071004SDavid Howells */ 260f071004SDavid Howells static int mtd_test_super(struct super_block *sb, struct fs_context *fc) 270f071004SDavid Howells { 280f071004SDavid Howells struct mtd_info *mtd = fc->sget_key; 290f071004SDavid Howells 300f071004SDavid Howells if (sb->s_mtd == fc->sget_key) { 310f071004SDavid Howells pr_debug("MTDSB: Match on device %d (\"%s\")\n", 320f071004SDavid Howells mtd->index, mtd->name); 330f071004SDavid Howells return 1; 340f071004SDavid Howells } 350f071004SDavid Howells 360f071004SDavid Howells pr_debug("MTDSB: No match, device %d (\"%s\"), device %d (\"%s\")\n", 370f071004SDavid Howells sb->s_mtd->index, sb->s_mtd->name, mtd->index, mtd->name); 380f071004SDavid Howells return 0; 390f071004SDavid Howells } 400f071004SDavid Howells 410f071004SDavid Howells /* 420f071004SDavid Howells * mark the superblock by the MTD device it is using 430f071004SDavid Howells * - set the device number to be the correct MTD block device for pesuperstence 440f071004SDavid Howells * of NFS exports 450f071004SDavid Howells */ 460f071004SDavid Howells static int mtd_set_super(struct super_block *sb, struct fs_context *fc) 470f071004SDavid Howells { 480f071004SDavid Howells sb->s_mtd = fc->sget_key; 490f071004SDavid Howells sb->s_dev = MKDEV(MTD_BLOCK_MAJOR, sb->s_mtd->index); 500f071004SDavid Howells sb->s_bdi = bdi_get(mtd_bdi); 510f071004SDavid Howells return 0; 520f071004SDavid Howells } 530f071004SDavid Howells 540f071004SDavid Howells /* 550f071004SDavid Howells * get a superblock on an MTD-backed filesystem 560f071004SDavid Howells */ 570f071004SDavid Howells static int mtd_get_sb(struct fs_context *fc, 580f071004SDavid Howells struct mtd_info *mtd, 590f071004SDavid Howells int (*fill_super)(struct super_block *, 600f071004SDavid Howells struct fs_context *)) 610f071004SDavid Howells { 620f071004SDavid Howells struct super_block *sb; 630f071004SDavid Howells int ret; 640f071004SDavid Howells 650f071004SDavid Howells fc->sget_key = mtd; 660f071004SDavid Howells sb = sget_fc(fc, mtd_test_super, mtd_set_super); 670f071004SDavid Howells if (IS_ERR(sb)) 680f071004SDavid Howells return PTR_ERR(sb); 690f071004SDavid Howells 700f071004SDavid Howells if (sb->s_root) { 710f071004SDavid Howells /* new mountpoint for an already mounted superblock */ 720f071004SDavid Howells pr_debug("MTDSB: Device %d (\"%s\") is already mounted\n", 730f071004SDavid Howells mtd->index, mtd->name); 740f071004SDavid Howells put_mtd_device(mtd); 750f071004SDavid Howells } else { 760f071004SDavid Howells /* fresh new superblock */ 770f071004SDavid Howells pr_debug("MTDSB: New superblock for device %d (\"%s\")\n", 780f071004SDavid Howells mtd->index, mtd->name); 790f071004SDavid Howells 800f071004SDavid Howells ret = fill_super(sb, fc); 810f071004SDavid Howells if (ret < 0) 820f071004SDavid Howells goto error_sb; 830f071004SDavid Howells 840f071004SDavid Howells sb->s_flags |= SB_ACTIVE; 850f071004SDavid Howells } 860f071004SDavid Howells 870f071004SDavid Howells BUG_ON(fc->root); 880f071004SDavid Howells fc->root = dget(sb->s_root); 890f071004SDavid Howells return 0; 900f071004SDavid Howells 910f071004SDavid Howells error_sb: 920f071004SDavid Howells deactivate_locked_super(sb); 930f071004SDavid Howells return ret; 940f071004SDavid Howells } 950f071004SDavid Howells 960f071004SDavid Howells /* 970f071004SDavid Howells * get a superblock on an MTD-backed filesystem by MTD device number 980f071004SDavid Howells */ 990f071004SDavid Howells static int mtd_get_sb_by_nr(struct fs_context *fc, int mtdnr, 1000f071004SDavid Howells int (*fill_super)(struct super_block *, 1010f071004SDavid Howells struct fs_context *)) 1020f071004SDavid Howells { 1030f071004SDavid Howells struct mtd_info *mtd; 1040f071004SDavid Howells 1050f071004SDavid Howells mtd = get_mtd_device(NULL, mtdnr); 1060f071004SDavid Howells if (IS_ERR(mtd)) { 1070f071004SDavid Howells errorf(fc, "MTDSB: Device #%u doesn't appear to exist\n", mtdnr); 1080f071004SDavid Howells return PTR_ERR(mtd); 1090f071004SDavid Howells } 1100f071004SDavid Howells 1110f071004SDavid Howells return mtd_get_sb(fc, mtd, fill_super); 1120f071004SDavid Howells } 1130f071004SDavid Howells 1140f071004SDavid Howells /** 1150f071004SDavid Howells * get_tree_mtd - Get a superblock based on a single MTD device 1160f071004SDavid Howells * @fc: The filesystem context holding the parameters 1170f071004SDavid Howells * @fill_super: Helper to initialise a new superblock 1180f071004SDavid Howells */ 1190f071004SDavid Howells int get_tree_mtd(struct fs_context *fc, 1200f071004SDavid Howells int (*fill_super)(struct super_block *sb, 1210f071004SDavid Howells struct fs_context *fc)) 1220f071004SDavid Howells { 1230f071004SDavid Howells #ifdef CONFIG_BLOCK 1244e7b5671SChristoph Hellwig dev_t dev; 1254e7b5671SChristoph Hellwig int ret; 1260f071004SDavid Howells #endif 1270f071004SDavid Howells int mtdnr; 1280f071004SDavid Howells 1290f071004SDavid Howells if (!fc->source) 1300f071004SDavid Howells return invalf(fc, "No source specified"); 1310f071004SDavid Howells 1320f071004SDavid Howells pr_debug("MTDSB: dev_name \"%s\"\n", fc->source); 1330f071004SDavid Howells 1340f071004SDavid Howells /* the preferred way of mounting in future; especially when 1350f071004SDavid Howells * CONFIG_BLOCK=n - we specify the underlying MTD device by number or 1360f071004SDavid Howells * by name, so that we don't require block device support to be present 1370f071004SDavid Howells * in the kernel. 1380f071004SDavid Howells */ 1390f071004SDavid Howells if (fc->source[0] == 'm' && 1400f071004SDavid Howells fc->source[1] == 't' && 1410f071004SDavid Howells fc->source[2] == 'd') { 1420f071004SDavid Howells if (fc->source[3] == ':') { 1430f071004SDavid Howells struct mtd_info *mtd; 1440f071004SDavid Howells 1450f071004SDavid Howells /* mount by MTD device name */ 1460f071004SDavid Howells pr_debug("MTDSB: mtd:%%s, name \"%s\"\n", 1470f071004SDavid Howells fc->source + 4); 1480f071004SDavid Howells 1490f071004SDavid Howells mtd = get_mtd_device_nm(fc->source + 4); 1500f071004SDavid Howells if (!IS_ERR(mtd)) 1510f071004SDavid Howells return mtd_get_sb(fc, mtd, fill_super); 1520f071004SDavid Howells 1530f071004SDavid Howells errorf(fc, "MTD: MTD device with name \"%s\" not found", 1540f071004SDavid Howells fc->source + 4); 1550f071004SDavid Howells 1560f071004SDavid Howells } else if (isdigit(fc->source[3])) { 1570f071004SDavid Howells /* mount by MTD device number name */ 1580f071004SDavid Howells char *endptr; 1590f071004SDavid Howells 1600f071004SDavid Howells mtdnr = simple_strtoul(fc->source + 3, &endptr, 0); 1610f071004SDavid Howells if (!*endptr) { 1620f071004SDavid Howells /* It was a valid number */ 1630f071004SDavid Howells pr_debug("MTDSB: mtd%%d, mtdnr %d\n", mtdnr); 1640f071004SDavid Howells return mtd_get_sb_by_nr(fc, mtdnr, fill_super); 1650f071004SDavid Howells } 1660f071004SDavid Howells } 1670f071004SDavid Howells } 1680f071004SDavid Howells 1690f071004SDavid Howells #ifdef CONFIG_BLOCK 1700f071004SDavid Howells /* try the old way - the hack where we allowed users to mount 1710f071004SDavid Howells * /dev/mtdblock$(n) but didn't actually _use_ the blockdev 1720f071004SDavid Howells */ 1734e7b5671SChristoph Hellwig ret = lookup_bdev(fc->source, &dev); 1744e7b5671SChristoph Hellwig if (ret) { 1750f071004SDavid Howells errorf(fc, "MTD: Couldn't look up '%s': %d", fc->source, ret); 1760f071004SDavid Howells return ret; 1770f071004SDavid Howells } 1780f071004SDavid Howells pr_debug("MTDSB: lookup_bdev() returned 0\n"); 1790f071004SDavid Howells 1804e7b5671SChristoph Hellwig if (MAJOR(dev) == MTD_BLOCK_MAJOR) 1814e7b5671SChristoph Hellwig return mtd_get_sb_by_nr(fc, MINOR(dev), fill_super); 1820f071004SDavid Howells 1830f071004SDavid Howells #endif /* CONFIG_BLOCK */ 1840f071004SDavid Howells 1850f071004SDavid Howells if (!(fc->sb_flags & SB_SILENT)) 1860f071004SDavid Howells errorf(fc, "MTD: Attempt to mount non-MTD device \"%s\"", 1870f071004SDavid Howells fc->source); 1880f071004SDavid Howells return -EINVAL; 1890f071004SDavid Howells } 1900f071004SDavid Howells EXPORT_SYMBOL_GPL(get_tree_mtd); 191acaebfd8SDavid Howells 192acaebfd8SDavid Howells /* 193acaebfd8SDavid Howells * destroy an MTD-based superblock 194acaebfd8SDavid Howells */ 195acaebfd8SDavid Howells void kill_mtd_super(struct super_block *sb) 196acaebfd8SDavid Howells { 197acaebfd8SDavid Howells generic_shutdown_super(sb); 198acaebfd8SDavid Howells put_mtd_device(sb->s_mtd); 199acaebfd8SDavid Howells sb->s_mtd = NULL; 200acaebfd8SDavid Howells } 201acaebfd8SDavid Howells 202acaebfd8SDavid Howells EXPORT_SYMBOL_GPL(kill_mtd_super); 203