super.c

ARM 嵌入式 系统 设计与实例开发 实验教材 二源码

/*
 *  linux/fs/ext2/super.c
 *
 * Copyright (C) 1992, 1993, 1994, 1995
 * Remy Card ([e-mail])
 * Laboratoire MASI - Institut Blaise Pascal
 * Universite Pierre et Marie Curie (Paris VI)
 *
 *  from
 *
 *  linux/fs/minix/inode.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 *  Big-endian to little-endian byte-swapping/bitmaps by
 *        David S. Miller ([e-mail]), 1995
 */

#include <linux/config.h>
#include <linux/module.h>
#include <linux/string.h>
#include <linux/fs.h>
#include <linux/ext2_fs.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/locks.h>
#include <linux/blkdev.h>
#include <asm/uaccess.h>


static void ext2_sync_super(struct super_block *sb,
			    struct ext2_super_block *es);

static char error_buf[1024];

void ext2_error (struct super_block * sb, const char * function,
		 const char * fmt, ...)
{
	va_list args;
	struct ext2_super_block *es = EXT2_SB(sb)->s_es;

	if (!(sb->s_flags & MS_RDONLY)) {
		sb->u.ext2_sb.s_mount_state |= EXT2_ERROR_FS;
		es->s_state =
			cpu_to_le16(le16_to_cpu(es->s_state) | EXT2_ERROR_FS);
		ext2_sync_super(sb, es);
	}
	va_start (args, fmt);
	vsprintf (error_buf, fmt, args);
	va_end (args);
	if (test_opt (sb, ERRORS_PANIC) ||
	    (le16_to_cpu(sb->u.ext2_sb.s_es->s_errors) == EXT2_ERRORS_PANIC &&
	     !test_opt (sb, ERRORS_CONT) && !test_opt (sb, ERRORS_RO)))
		panic ("EXT2-fs panic (device %s): %s: %s\n",
		       bdevname(sb->s_dev), function, error_buf);
	printk (KERN_CRIT "EXT2-fs error (device %s): %s: %s\n",
		bdevname(sb->s_dev), function, error_buf);
	if (test_opt (sb, ERRORS_RO) ||
	    (le16_to_cpu(sb->u.ext2_sb.s_es->s_errors) == EXT2_ERRORS_RO &&
	     !test_opt (sb, ERRORS_CONT) && !test_opt (sb, ERRORS_PANIC))) {
		printk ("Remounting filesystem read-only\n");
		sb->s_flags |= MS_RDONLY;
	}
}

NORET_TYPE void ext2_panic (struct super_block * sb, const char * function,
			    const char * fmt, ...)
{
	va_list args;

	if (!(sb->s_flags & MS_RDONLY)) {
		sb->u.ext2_sb.s_mount_state |= EXT2_ERROR_FS;
		sb->u.ext2_sb.s_es->s_state =
			cpu_to_le16(le16_to_cpu(sb->u.ext2_sb.s_es->s_state) | EXT2_ERROR_FS);
		mark_buffer_dirty(sb->u.ext2_sb.s_sbh);
		sb->s_dirt = 1;
	}
	va_start (args, fmt);
	vsprintf (error_buf, fmt, args);
	va_end (args);
	sb->s_flags |= MS_RDONLY;
	panic ("EXT2-fs panic (device %s): %s: %s\n",
	       bdevname(sb->s_dev), function, error_buf);
}

void ext2_warning (struct super_block * sb, const char * function,
		   const char * fmt, ...)
{
	va_list args;

	va_start (args, fmt);
	vsprintf (error_buf, fmt, args);
	va_end (args);
	printk (KERN_WARNING "EXT2-fs warning (device %s): %s: %s\n",
		bdevname(sb->s_dev), function, error_buf);
}

void ext2_update_dynamic_rev(struct super_block *sb)
{
	struct ext2_super_block *es = EXT2_SB(sb)->s_es;

	if (le32_to_cpu(es->s_rev_level) > EXT2_GOOD_OLD_REV)
		return;

	ext2_warning(sb, __FUNCTION__,
		     "updating to rev %d because of new feature flag, "
		     "running e2fsck is recommended",
		     EXT2_DYNAMIC_REV);

	es->s_first_ino = cpu_to_le32(EXT2_GOOD_OLD_FIRST_INO);
	es->s_inode_size = cpu_to_le16(EXT2_GOOD_OLD_INODE_SIZE);
	es->s_rev_level = cpu_to_le32(EXT2_DYNAMIC_REV);
	/* leave es->s_feature_*compat flags alone */
	/* es->s_uuid will be set by e2fsck if empty */

	/*
	 * The rest of the superblock fields should be zero, and if not it
	 * means they are likely already in use, so leave them alone.  We
	 * can leave it up to e2fsck to clean up any inconsistencies there.
	 */
}

void ext2_put_super (struct super_block * sb)
{
	int db_count;
	int i;

	if (!(sb->s_flags & MS_RDONLY)) {
		struct ext2_super_block *es = EXT2_SB(sb)->s_es;

		es->s_state = le16_to_cpu(EXT2_SB(sb)->s_mount_state);
		ext2_sync_super(sb, es);
	}
	db_count = EXT2_SB(sb)->s_gdb_count;
	for (i = 0; i < db_count; i++)
		if (sb->u.ext2_sb.s_group_desc[i])
			brelse (sb->u.ext2_sb.s_group_desc[i]);
	kfree(sb->u.ext2_sb.s_group_desc);
	for (i = 0; i < EXT2_MAX_GROUP_LOADED; i++)
		if (sb->u.ext2_sb.s_inode_bitmap[i])
			brelse (sb->u.ext2_sb.s_inode_bitmap[i]);
	for (i = 0; i < EXT2_MAX_GROUP_LOADED; i++)
		if (sb->u.ext2_sb.s_block_bitmap[i])
			brelse (sb->u.ext2_sb.s_block_bitmap[i]);
	brelse (sb->u.ext2_sb.s_sbh);

	return;
}

static struct super_operations ext2_sops = {
	read_inode:	ext2_read_inode,
	write_inode:	ext2_write_inode,
	put_inode:	ext2_put_inode,
	delete_inode:	ext2_delete_inode,
	put_super:	ext2_put_super,
	write_super:	ext2_write_super,
	statfs:		ext2_statfs,
	remount_fs:	ext2_remount,
};

/*
 * This function has been shamelessly adapted from the msdos fs
 */
static int parse_options (char * options, unsigned long * sb_block,
			  unsigned short *resuid, unsigned short * resgid,
			  unsigned long * mount_options)
{
	char * this_char;
	char * value;

	if (!options)
		return 1;
	for (this_char = strtok (options, ",");
	     this_char != NULL;
	     this_char = strtok (NULL, ",")) {
		if ((value = strchr (this_char, '=')) != NULL)
			*value++ = 0;
		if (!strcmp (this_char, "bsddf"))
			clear_opt (*mount_options, MINIX_DF);
		else if (!strcmp (this_char, "nouid32")) {
			set_opt (*mount_options, NO_UID32);
		}
		else if (!strcmp (this_char, "check")) {
			if (!value || !*value || !strcmp (value, "none"))
				clear_opt (*mount_options, CHECK);
			else
#ifdef CONFIG_EXT2_CHECK
				set_opt (*mount_options, CHECK);
#else
				printk("EXT2 Check option not supported\n");
#endif
		}
		else if (!strcmp (this_char, "debug"))
			set_opt (*mount_options, DEBUG);
		else if (!strcmp (this_char, "errors")) {
			if (!value || !*value) {
				printk ("EXT2-fs: the errors option requires "
					"an argument\n");
				return 0;
			}
			if (!strcmp (value, "continue")) {
				clear_opt (*mount_options, ERRORS_RO);
				clear_opt (*mount_options, ERRORS_PANIC);
				set_opt (*mount_options, ERRORS_CONT);
			}
			else if (!strcmp (value, "remount-ro")) {
				clear_opt (*mount_options, ERRORS_CONT);
				clear_opt (*mount_options, ERRORS_PANIC);
				set_opt (*mount_options, ERRORS_RO);
			}
			else if (!strcmp (value, "panic")) {
				clear_opt (*mount_options, ERRORS_CONT);
				clear_opt (*mount_options, ERRORS_RO);
				set_opt (*mount_options, ERRORS_PANIC);
			}
			else {
				printk ("EXT2-fs: Invalid errors option: %s\n",
					value);
				return 0;
			}
		}
		else if (!strcmp (this_char, "grpid") ||
			 !strcmp (this_char, "bsdgroups"))
			set_opt (*mount_options, GRPID);
		else if (!strcmp (this_char, "minixdf"))
			set_opt (*mount_options, MINIX_DF);
		else if (!strcmp (this_char, "nocheck"))
			clear_opt (*mount_options, CHECK);
		else if (!strcmp (this_char, "nogrpid") ||
			 !strcmp (this_char, "sysvgroups"))
			clear_opt (*mount_options, GRPID);
		else if (!strcmp (this_char, "resgid")) {
			if (!value || !*value) {
				printk ("EXT2-fs: the resgid option requires "
					"an argument\n");
				return 0;
			}
			*resgid = simple_strtoul (value, &value, 0);
			if (*value) {
				printk ("EXT2-fs: Invalid resgid option: %s\n",
					value);
				return 0;
			}
		}
		else if (!strcmp (this_char, "resuid")) {
			if (!value || !*value) {
				printk ("EXT2-fs: the resuid option requires "
					"an argument");
				return 0;
			}
			*resuid = simple_strtoul (value, &value, 0);
			if (*value) {
				printk ("EXT2-fs: Invalid resuid option: %s\n",
					value);
				return 0;
			}
		}
		else if (!strcmp (this_char, "sb")) {
			if (!value || !*value) {
				printk ("EXT2-fs: the sb option requires "
					"an argument");
				return 0;
			}
			*sb_block = simple_strtoul (value, &value, 0);
			if (*value) {
				printk ("EXT2-fs: Invalid sb option: %s\n",
					value);
				return 0;
			}
		}
		/* Silently ignore the quota options */
		else if (!strcmp (this_char, "grpquota")
		         || !strcmp (this_char, "noquota")
		         || !strcmp (this_char, "quota")
		         || !strcmp (this_char, "usrquota"))
			/* Don't do anything ;-) */ ;
		else {
			printk ("EXT2-fs: Unrecognized mount option %s\n", this_char);
			return 0;
		}
	}
	return 1;
}

static int ext2_setup_super (struct super_block * sb,
			      struct ext2_super_block * es,
			      int read_only)
{
	int res = 0;
	if (le32_to_cpu(es->s_rev_level) > EXT2_MAX_SUPP_REV) {
		printk ("EXT2-fs warning: revision level too high, "
			"forcing read-only mode\n");
		res = MS_RDONLY;
	}
	if (read_only)
		return res;
	if (!(sb->u.ext2_sb.s_mount_state & EXT2_VALID_FS))
		printk ("EXT2-fs warning: mounting unchecked fs, "
			"running e2fsck is recommended\n");
	else if ((sb->u.ext2_sb.s_mount_state & EXT2_ERROR_FS))
		printk ("EXT2-fs warning: mounting fs with errors, "
			"running e2fsck is recommended\n");
	else if ((__s16) le16_to_cpu(es->s_max_mnt_count) >= 0 &&
		 le16_to_cpu(es->s_mnt_count) >=
		 (unsigned short) (__s16) le16_to_cpu(es->s_max_mnt_count))
		printk ("EXT2-fs warning: maximal mount count reached, "
			"running e2fsck is recommended\n");
	else if (le32_to_cpu(es->s_checkinterval) &&
		(le32_to_cpu(es->s_lastcheck) + le32_to_cpu(es->s_checkinterval) <= CURRENT_TIME))
		printk ("EXT2-fs warning: checktime reached, "
			"running e2fsck is recommended\n");
	if (!(__s16) le16_to_cpu(es->s_max_mnt_count))
		es->s_max_mnt_count = (__s16) cpu_to_le16(EXT2_DFL_MAX_MNT_COUNT);
	es->s_mnt_count=cpu_to_le16(le16_to_cpu(es->s_mnt_count) + 1);
	ext2_write_super(sb);
	if (test_opt (sb, DEBUG))
		printk ("[EXT II FS %s, %s, bs=%lu, fs=%lu, gc=%lu, "
			"bpg=%lu, ipg=%lu, mo=%04lx]\n",
			EXT2FS_VERSION, EXT2FS_DATE, sb->s_blocksize,
			sb->u.ext2_sb.s_frag_size,
			sb->u.ext2_sb.s_groups_count,
			EXT2_BLOCKS_PER_GROUP(sb),
			EXT2_INODES_PER_GROUP(sb),
			sb->u.ext2_sb.s_mount_opt);
#ifdef CONFIG_EXT2_CHECK
	if (test_opt (sb, CHECK)) {
		ext2_check_blocks_bitmap (sb);
		ext2_check_inodes_bitmap (sb);
	}
#endif
	return res;
}

static int ext2_check_descriptors (struct super_block * sb)
{
	int i;
	int desc_block = 0;
	unsigned long block = le32_to_cpu(sb->u.ext2_sb.s_es->s_first_data_block);
	struct ext2_group_desc * gdp = NULL;

	ext2_debug ("Checking group descriptors");

	for (i = 0; i < sb->u.ext2_sb.s_groups_count; i++)
	{
		if ((i % EXT2_DESC_PER_BLOCK(sb)) == 0)
			gdp = (struct ext2_group_desc *) sb->u.ext2_sb.s_group_desc[desc_block++]->b_data;
		if (le32_to_cpu(gdp->bg_block_bitmap) < block ||
		    le32_to_cpu(gdp->bg_block_bitmap) >= block + EXT2_BLOCKS_PER_GROUP(sb))
		{
			ext2_error (sb, "ext2_check_descriptors",
				    "Block bitmap for group %d"
				    " not in group (block %lu)!",
				    i, (unsigned long) le32_to_cpu(gdp->bg_block_bitmap));
			return 0;
		}
		if (le32_to_cpu(gdp->bg_inode_bitmap) < block ||
		    le32_to_cpu(gdp->bg_inode_bitmap) >= block + EXT2_BLOCKS_PER_GROUP(sb))
		{
			ext2_error (sb, "ext2_check_descriptors",
				    "Inode bitmap for group %d"
				    " not in group (block %lu)!",
				    i, (unsigned long) le32_to_cpu(gdp->bg_inode_bitmap));
			return 0;
		}
		if (le32_to_cpu(gdp->bg_inode_table) < block ||
		    le32_to_cpu(gdp->bg_inode_table) + sb->u.ext2_sb.s_itb_per_group >=
		    block + EXT2_BLOCKS_PER_GROUP(sb))
		{
			ext2_error (sb, "ext2_check_descriptors",
				    "Inode table for group %d"
				    " not in group (block %lu)!",
				    i, (unsigned long) le32_to_cpu(gdp->bg_inode_table));
			return 0;
		}
		block += EXT2_BLOCKS_PER_GROUP(sb);
		gdp++;
	}
	return 1;
}

#define log2(n) ffz(~(n))
 
/*
 * Maximal file size.  There is a direct, and {,double-,triple-}indirect
 * block limit, and also a limit of (2^32 - 1) 512-byte sectors in i_blocks.
 * We need to be 1 filesystem block less than the 2^32 sector limit.
 */
static loff_t ext2_max_size(int bits)
{
	loff_t res = EXT2_NDIR_BLOCKS;
	res += 1LL << (bits-2);
	res += 1LL << (2*(bits-2));
	res += 1LL << (3*(bits-2));
	res <<= bits;
	if (res > (512LL << 32) - (1 << bits))
		res = (512LL << 32) - (1 << bits);
	return res;
}

struct super_block * ext2_read_super (struct super_block * sb, void * data,
				      int silent)
{
	struct buffer_head * bh;
	struct ext2_super_block * es;
	unsigned long sb_block = 1;
	unsigned short resuid = EXT2_DEF_RESUID;
	unsigned short resgid = EXT2_DEF_RESGID;
	unsigned long logic_sb_block = 1;
	unsigned long offset = 0;
	kdev_t dev = sb->s_dev;
	int blocksize = BLOCK_SIZE;
	int db_count;
	int i, j;