patch-2.4.6 linux/fs/sysv/super.c

• Lines: 468
• Date: Mon Jul 2 14:03:04 2001
• Orig file: v2.4.5/linux/fs/sysv/super.c
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.4.5/linux/fs/sysv/super.c linux/fs/sysv/super.c
@@ -0,0 +1,467 @@
+/*
+ *  linux/fs/sysv/inode.c
+ *
+ *  minix/inode.c
+ *  Copyright (C) 1991, 1992  Linus Torvalds
+ *
+ *  xenix/inode.c
+ *  Copyright (C) 1992  Doug Evans
+ *
+ *  coh/inode.c
+ *  Copyright (C) 1993  Pascal Haible, Bruno Haible
+ *
+ *  sysv/inode.c
+ *  Copyright (C) 1993  Paul B. Monday
+ *
+ *  sysv/inode.c
+ *  Copyright (C) 1993  Bruno Haible
+ *  Copyright (C) 1997, 1998  Krzysztof G. Baranowski
+ *
+ *  This file contains code for read/parsing the superblock.
+ */
+
+#include <linux/module.h>
+
+#include <linux/fs.h>
+#include <linux/sysv_fs.h>
+#include <linux/init.h>
+
+/* The following functions try to recognize specific filesystems.
+ * We recognize:
+ * - Xenix FS by its magic number.
+ * - SystemV FS by its magic number.
+ * - Coherent FS by its funny fname/fpack field.
+ * We discriminate among SystemV4 and SystemV2 FS by the assumption that
+ * the time stamp is not < 01-01-1980.
+ */
+
+enum {
+	JAN_1_1980 = (10*365 + 2) * 24 * 60 * 60
+};
+
+static void detected_xenix(struct super_block *sb)
+{
+	struct buffer_head *bh1 = sb->sv_bh1;
+	struct buffer_head *bh2 = sb->sv_bh2;
+	struct xenix_super_block * sbd1;
+	struct xenix_super_block * sbd2;
+
+	if (bh1 != bh2)
+		sbd1 = sbd2 = (struct xenix_super_block *) bh1->b_data;
+	else {
+		/* block size = 512, so bh1 != bh2 */
+		sbd1 = (struct xenix_super_block *) bh1->b_data;
+		sbd2 = (struct xenix_super_block *) (bh2->b_data - 512);
+	}
+
+	sb->sv_link_max = XENIX_LINK_MAX;
+	sb->sv_fic_size = XENIX_NICINOD;
+	sb->sv_flc_size = XENIX_NICFREE;
+	sb->sv_sbd1 = (char *) sbd1;
+	sb->sv_sbd2 = (char *) sbd2;
+	sb->sv_sb_fic_count = &sbd1->s_ninode;
+	sb->sv_sb_fic_inodes = &sbd1->s_inode[0];
+	sb->sv_sb_total_free_inodes = &sbd2->s_tinode;
+	sb->sv_bcache_count = &sbd1->s_nfree;
+	sb->sv_bcache = &sbd1->s_free[0];
+	sb->sv_free_blocks = &sbd2->s_tfree;
+	sb->sv_sb_time = &sbd2->s_time;
+	sb->sv_firstdatazone = fs16_to_cpu(sb, sbd1->s_isize);
+	sb->sv_nzones = fs32_to_cpu(sb, sbd1->s_fsize);
+}
+
+static void detected_sysv4(struct super_block *sb)
+{
+	struct sysv4_super_block * sbd;
+	struct buffer_head *bh1 = sb->sv_bh1;
+	struct buffer_head *bh2 = sb->sv_bh2;
+
+	if (bh1 == bh2)
+		sbd = (struct sysv4_super_block *) (bh1->b_data + BLOCK_SIZE/2);
+	else
+		sbd = (struct sysv4_super_block *) bh2->b_data;
+
+	sb->sv_link_max = SYSV_LINK_MAX;
+	sb->sv_fic_size = SYSV_NICINOD;
+	sb->sv_flc_size = SYSV_NICFREE;
+	sb->sv_sbd1 = (char *) sbd;
+	sb->sv_sbd2 = (char *) sbd;
+	sb->sv_sb_fic_count = &sbd->s_ninode;
+	sb->sv_sb_fic_inodes = &sbd->s_inode[0];
+	sb->sv_sb_total_free_inodes = &sbd->s_tinode;
+	sb->sv_bcache_count = &sbd->s_nfree;
+	sb->sv_bcache = &sbd->s_free[0];
+	sb->sv_free_blocks = &sbd->s_tfree;
+	sb->sv_sb_time = &sbd->s_time;
+	sb->sv_sb_state = &sbd->s_state;
+	sb->sv_firstdatazone = fs16_to_cpu(sb, sbd->s_isize);
+	sb->sv_nzones = fs32_to_cpu(sb, sbd->s_fsize);
+}
+
+static void detected_sysv2(struct super_block *sb)
+{
+	struct sysv2_super_block * sbd;
+	struct buffer_head *bh1 = sb->sv_bh1;
+	struct buffer_head *bh2 = sb->sv_bh2;
+
+	if (bh1 == bh2)
+		sbd = (struct sysv2_super_block *) (bh1->b_data + BLOCK_SIZE/2);
+	else
+		sbd = (struct sysv2_super_block *) bh2->b_data;
+
+	sb->sv_link_max = SYSV_LINK_MAX;
+	sb->sv_fic_size = SYSV_NICINOD;
+	sb->sv_flc_size = SYSV_NICFREE;
+	sb->sv_sbd1 = (char *) sbd;
+	sb->sv_sbd2 = (char *) sbd;
+	sb->sv_sb_fic_count = &sbd->s_ninode;
+	sb->sv_sb_fic_inodes = &sbd->s_inode[0];
+	sb->sv_sb_total_free_inodes = &sbd->s_tinode;
+	sb->sv_bcache_count = &sbd->s_nfree;
+	sb->sv_bcache = &sbd->s_free[0];
+	sb->sv_free_blocks = &sbd->s_tfree;
+	sb->sv_sb_time = &sbd->s_time;
+	sb->sv_sb_state = &sbd->s_state;
+	sb->sv_firstdatazone = fs16_to_cpu(sb, sbd->s_isize);
+	sb->sv_nzones = fs32_to_cpu(sb, sbd->s_fsize);
+}
+
+static void detected_coherent(struct super_block *sb)
+{
+	struct coh_super_block * sbd;
+	struct buffer_head *bh1 = sb->sv_bh1;
+
+	sbd = (struct coh_super_block *) bh1->b_data;
+
+	sb->sv_link_max = COH_LINK_MAX;
+	sb->sv_fic_size = COH_NICINOD;
+	sb->sv_flc_size = COH_NICFREE;
+	sb->sv_sbd1 = (char *) sbd;
+	sb->sv_sbd2 = (char *) sbd;
+	sb->sv_sb_fic_count = &sbd->s_ninode;
+	sb->sv_sb_fic_inodes = &sbd->s_inode[0];
+	sb->sv_sb_total_free_inodes = &sbd->s_tinode;
+	sb->sv_bcache_count = &sbd->s_nfree;
+	sb->sv_bcache = &sbd->s_free[0];
+	sb->sv_free_blocks = &sbd->s_tfree;
+	sb->sv_sb_time = &sbd->s_time;
+	sb->sv_firstdatazone = fs16_to_cpu(sb, sbd->s_isize);
+	sb->sv_nzones = fs32_to_cpu(sb, sbd->s_fsize);
+}
+
+static void detected_v7(struct super_block *sb)
+{
+	struct buffer_head *bh2 = sb->sv_bh2;
+	struct v7_super_block *sbd = (struct v7_super_block *)bh2->b_data;
+
+	sb->sv_link_max = V7_LINK_MAX;
+	sb->sv_fic_size = V7_NICINOD;
+	sb->sv_flc_size = V7_NICFREE;
+	sb->sv_sbd1 = (char *)sbd;
+	sb->sv_sbd2 = (char *)sbd;
+	sb->sv_sb_fic_count = &sbd->s_ninode;
+	sb->sv_sb_fic_inodes = &sbd->s_inode[0];
+	sb->sv_sb_total_free_inodes = &sbd->s_tinode;
+	sb->sv_bcache_count = &sbd->s_nfree;
+	sb->sv_bcache = &sbd->s_free[0];
+	sb->sv_free_blocks = &sbd->s_tfree;
+	sb->sv_sb_time = &sbd->s_time;
+	sb->sv_firstdatazone = fs16_to_cpu(sb, sbd->s_isize);
+	sb->sv_nzones = fs32_to_cpu(sb, sbd->s_fsize);
+}
+
+static int detect_xenix (struct super_block *sb, struct buffer_head *bh)
+{
+	struct xenix_super_block * sbd = (struct xenix_super_block *)bh->b_data;
+	if (sbd->s_magic == cpu_to_le32(0x2b5544))
+		sb->sv_bytesex = BYTESEX_LE;
+	else if (sbd->s_magic == cpu_to_be32(0x2b5544))
+		sb->sv_bytesex = BYTESEX_BE;
+	else
+		return 0;
+	if (sbd->s_type > 2 || sbd->s_type < 1)
+		return 0;
+	sb->sv_type = FSTYPE_XENIX;
+	return sbd->s_type;
+}
+
+static int detect_sysv (struct super_block *sb, struct buffer_head *bh)
+{
+	/* All relevant fields are at the same offsets in R2 and R4 */
+	struct sysv4_super_block * sbd;
+
+	sbd = (struct sysv4_super_block *) (bh->b_data + BLOCK_SIZE/2);
+	if (sbd->s_magic == cpu_to_le32(0xfd187e20))
+		sb->sv_bytesex = BYTESEX_LE;
+	else if (sbd->s_magic == cpu_to_be32(0xfd187e20))
+		sb->sv_bytesex = BYTESEX_BE;
+	else
+		return 0;
+	if (sbd->s_time < JAN_1_1980) {
+		/* this is likely to happen on SystemV2 FS */
+		if (sbd->s_type > 3 || sbd->s_type < 1)
+			return 0;
+		sb->sv_type = FSTYPE_SYSV2;
+		return sbd->s_type;
+	}
+	if ((sbd->s_type > 3 || sbd->s_type < 1) &&
+	    (sbd->s_type > 0x30 || sbd->s_type < 0x10))
+		return 0;
+
+	/* On Interactive Unix (ISC) Version 4.0/3.x s_type field = 0x10,
+	   0x20 or 0x30 indicates that symbolic links and the 14-character
+	   filename limit is gone. Due to lack of information about this
+           feature read-only mode seems to be a reasonable approach... -KGB */
+
+	if (sbd->s_type >= 0x10) {
+		printk("SysV FS: can't handle long file names on %s, "
+		       "forcing read-only mode.\n", kdevname(sb->s_dev));
+		sb->s_flags |= MS_RDONLY;
+	}
+
+	sb->sv_type = FSTYPE_SYSV4;
+	return sbd->s_type >= 0x10 ? (sbd->s_type >> 4) : sbd->s_type;
+}
+
+static int detect_coherent (struct super_block *sb, struct buffer_head *bh)
+{
+	struct coh_super_block * sbd;
+
+	sbd = (struct coh_super_block *) (bh->b_data + BLOCK_SIZE/2);
+	if ((memcmp(sbd->s_fname,"noname",6) && memcmp(sbd->s_fname,"xxxxx ",6))
+	    || (memcmp(sbd->s_fpack,"nopack",6) && memcmp(sbd->s_fpack,"xxxxx\n",6)))
+		return 0;
+	sb->sv_bytesex = BYTESEX_PDP;
+	sb->sv_type = FSTYPE_COH;
+	return 1;
+}
+
+static int detect_sysv_odd(struct super_block *sb, struct buffer_head *bh)
+{
+	int size = detect_sysv(sb, bh);
+
+	return size>2 ? 0 : size;
+}
+
+static struct {
+	int block;
+	int (*test)(struct super_block *, struct buffer_head *);
+} flavours[] = {
+	{1, detect_xenix},
+	{0, detect_sysv},
+	{0, detect_coherent},
+	{9, detect_sysv_odd},
+	{15,detect_sysv_odd},
+	{18,detect_sysv},
+};
+
+static char *flavour_names[] = {
+	[FSTYPE_XENIX]	"Xenix",
+	[FSTYPE_SYSV4]	"SystemV",
+	[FSTYPE_SYSV2]	"SystemV Release 2",
+	[FSTYPE_COH]	"Coherent",
+	[FSTYPE_V7]	"V7",
+};
+
+static void (*flavour_setup[])(struct super_block *) = {
+	[FSTYPE_XENIX]	detected_xenix,
+	[FSTYPE_SYSV4]	detected_sysv4,
+	[FSTYPE_SYSV2]	detected_sysv2,
+	[FSTYPE_COH]	detected_coherent,
+	[FSTYPE_V7]	detected_v7,
+};
+
+static int complete_read_super(struct super_block *sb, int silent, int size)
+{
+	struct inode *root_inode;
+	char *found = flavour_names[sb->sv_type];
+	u_char n_bits = size+8;
+	int bsize = 1 << n_bits;
+	int bsize_4 = bsize >> 2;
+
+	sb->sv_kludge_symlinks = 1;
+	sb->sv_firstinodezone = 2;
+
+	flavour_setup[sb->sv_type](sb);
+	
+	sb->sv_truncate = 1;
+	sb->sv_ndatazones = sb->sv_nzones - sb->sv_firstdatazone;
+	sb->sv_inodes_per_block = bsize >> 6;
+	sb->sv_inodes_per_block_1 = (bsize >> 6)-1;
+	sb->sv_inodes_per_block_bits = n_bits-6;
+	sb->sv_ind_per_block = bsize_4;
+	sb->sv_ind_per_block_2 = bsize_4*bsize_4;
+	sb->sv_toobig_block = 10 + bsize_4 * (1 + bsize_4 * (1 + bsize_4));
+	sb->sv_ind_per_block_bits = n_bits-2;
+
+	sb->sv_ninodes = (sb->sv_firstdatazone - sb->sv_firstinodezone) << sb->sv_inodes_per_block_bits;
+
+	sb->s_blocksize = bsize;
+	sb->s_blocksize_bits = n_bits;
+	if (!silent)
+		printk("VFS: Found a %s FS (block size = %ld) on device %s\n",
+		       found, sb->s_blocksize, bdevname(sb->s_dev));
+
+	sb->s_magic = SYSV_MAGIC_BASE + sb->sv_type;
+	/* set up enough so that it can read an inode */
+	sb->s_op = &sysv_sops;
+	root_inode = iget(sb,SYSV_ROOT_INO);
+	if (!root_inode) {
+		printk("SysV FS: get root inode failed\n");
+		return 0;
+	}
+	sb->s_root = d_alloc_root(root_inode);
+	if (!sb->s_root) {
+		iput(root_inode);
+		printk("SysV FS: get root dentry failed\n");
+		return 0;
+	}
+	if (sb->sv_truncate)
+		sb->s_root->d_op = &sysv_dentry_operations;
+	sb->s_flags |= MS_RDONLY;
+	sb->s_dirt = 1;
+	return 1;
+}
+
+static struct super_block *sysv_read_super(struct super_block *sb,
+					   void *data, int silent)
+{
+	struct buffer_head *bh1;
+	struct buffer_head *bh = NULL;
+	kdev_t dev = sb->s_dev;
+	unsigned long blocknr;
+	int size = 0;
+	int i;
+	
+	if (1024 != sizeof (struct xenix_super_block))
+		panic("Xenix FS: bad super-block size");
+	if ((512 != sizeof (struct sysv4_super_block))
+            || (512 != sizeof (struct sysv2_super_block)))
+		panic("SystemV FS: bad super-block size");
+	if (500 != sizeof (struct coh_super_block))
+		panic("Coherent FS: bad super-block size");
+	if (64 != sizeof (struct sysv_inode))
+		panic("sysv fs: bad i-node size");
+	set_blocksize(dev,BLOCK_SIZE);
+	sb->sv_block_base = 0;
+
+	for (i = 0; i < sizeof(flavours)/sizeof(flavours[0]) && !size; i++) {
+		struct buffer_head *next_bh;
+		next_bh = bread(dev, flavours[i].block, BLOCK_SIZE);
+		if (!next_bh)
+			continue;
+		brelse(bh);
+		bh = next_bh;
+
+		size = flavours[i].test(sb, bh);
+	}
+
+	if (!size)
+		goto Eunknown;
+
+	switch (size) {
+		case 1:
+			blocknr = bh->b_blocknr << 1;
+			brelse(bh);
+			set_blocksize(dev, 512);
+			bh1 = bread(dev, blocknr, 512);
+			bh = bread(dev, blocknr + 1, 512);
+			break;
+		case 2:
+			bh1 = bh;
+			break;
+		case 3:
+			blocknr = bh->b_blocknr >> 1;
+			brelse(bh);
+			set_blocksize(dev, 2048);
+			bh1 = bh = bread(dev, blocknr, 2048);
+			break;
+		default:
+			goto Ebadsize;
+	}
+
+	if (bh && bh1) {
+		sb->sv_bh1 = bh1;
+		sb->sv_bh2 = bh;
+		if (complete_read_super(sb, silent, size))
+			return sb;
+	}
+
+	brelse(bh1);
+	brelse(bh);
+	set_blocksize(sb->s_dev,BLOCK_SIZE);
+	printk("oldfs: cannot read superblock\n");
+failed:
+	return NULL;
+
+Eunknown:
+	brelse(bh);
+	if (!silent)
+		printk("VFS: unable to find oldfs superblock on device %s\n",
+			bdevname(dev));
+	goto failed;
+Ebadsize:
+	brelse(bh);
+	if (!silent)
+		printk("VFS: oldfs: unsupported block size (%dKb)\n",
+			1<<(size-2));
+	goto failed;
+}
+
+static struct super_block *v7_read_super(struct super_block *sb,void *data,
+				  int silent)
+{
+	struct buffer_head *bh;
+	kdev_t dev = sb->s_dev;
+
+	if (440 != sizeof (struct v7_super_block))
+		panic("V7 FS: bad super-block size");
+	if (64 != sizeof (struct sysv_inode))
+		panic("sysv fs: bad i-node size");
+
+	sb->sv_type = FSTYPE_V7;
+	sb->sv_bytesex = BYTESEX_PDP;
+
+	set_blocksize(dev,512);
+
+	if ((bh = bread(dev, 1, 512)) == NULL) {
+		if (!silent)
+			printk("VFS: unable to read V7 FS superblock on device "
+			       "%s.\n", bdevname(dev));
+		goto failed;
+	}
+
+
+	sb->sv_bh1 = bh;
+	sb->sv_bh2 = bh;
+	if (complete_read_super(sb, silent, 1))
+		return sb;
+
+	brelse(bh);
+failed:
+	return NULL;
+}
+
+/* Every kernel module contains stuff like this. */
+
+static DECLARE_FSTYPE_DEV(sysv_fs_type, "sysv", sysv_read_super);
+static DECLARE_FSTYPE_DEV(v7_fs_type, "v7", v7_read_super);
+
+static int __init init_sysv_fs(void)
+{
+	int err = register_filesystem(&sysv_fs_type);
+	if (!err)
+		err = register_filesystem(&v7_fs_type);
+	return err;
+}
+
+static void __exit exit_sysv_fs(void)
+{
+	unregister_filesystem(&sysv_fs_type);
+	unregister_filesystem(&v7_fs_type);
+}
+
+EXPORT_NO_SYMBOLS;
+
+module_init(init_sysv_fs)
+module_exit(exit_sysv_fs)