inode.c

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/*
 *  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 allocating/freeing inodes and for read/writing
 *  the superblock.
 */

#include <linux/highuid.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/buffer_head.h>
#include <linux/vfs.h>
#include <linux/writeback.h>
#include <linux/namei.h>
#include <asm/byteorder.h>
#include "sysv.h"

static int sysv_sync_fs(struct super_block *sb, int wait)
{
    struct sysv_sb_info *sbi = SYSV_SB(sb);
    unsigned long time = get_seconds(), old_time;

    mutex_lock(&sbi->s_lock);

    /*
     * If we are going to write out the super block,
     * then attach current time stamp.
     * But if the filesystem was marked clean, keep it clean.
     */
    old_time = fs32_to_cpu(sbi, *sbi->s_sb_time);
    if (sbi->s_type == FSTYPE_SYSV4) {
        if (*sbi->s_sb_state == cpu_to_fs32(sbi, 0x7c269d38 - old_time))
            *sbi->s_sb_state = cpu_to_fs32(sbi, 0x7c269d38 - time);
        *sbi->s_sb_time = cpu_to_fs32(sbi, time);
        mark_buffer_dirty(sbi->s_bh2);
    }

    mutex_unlock(&sbi->s_lock);

    return 0;
}

static int sysv_remount(struct super_block *sb, int *flags, char *data)
{
    struct sysv_sb_info *sbi = SYSV_SB(sb);

    if (sbi->s_forced_ro)
        *flags |= MS_RDONLY;
    return 0;
}

static void sysv_put_super(struct super_block *sb)
{
    struct sysv_sb_info *sbi = SYSV_SB(sb);

    if (!(sb->s_flags & MS_RDONLY)) {
        /* XXX ext2 also updates the state here */
        mark_buffer_dirty(sbi->s_bh1);
        if (sbi->s_bh1 != sbi->s_bh2)
            mark_buffer_dirty(sbi->s_bh2);
    }

    brelse(sbi->s_bh1);
    if (sbi->s_bh1 != sbi->s_bh2)
        brelse(sbi->s_bh2);

    kfree(sbi);
}

static int sysv_statfs(struct dentry *dentry, struct kstatfs *buf)
{
    struct super_block *sb = dentry->d_sb;
    struct sysv_sb_info *sbi = SYSV_SB(sb);
    u64 id = huge_encode_dev(sb->s_bdev->bd_dev);

    buf->f_type = sb->s_magic;
    buf->f_bsize = sb->s_blocksize;
    buf->f_blocks = sbi->s_ndatazones;
    buf->f_bavail = buf->f_bfree = sysv_count_free_blocks(sb);
    buf->f_files = sbi->s_ninodes;
    buf->f_ffree = sysv_count_free_inodes(sb);
    buf->f_namelen = SYSV_NAMELEN;
    buf->f_fsid.val[0] = (u32)id;
    buf->f_fsid.val[1] = (u32)(id >> 32);
    return 0;
}

/* 
 * NXI <-> N0XI for PDP, XIN <-> XIN0 for le32, NIX <-> 0NIX for be32
 */
static inline void read3byte(struct sysv_sb_info *sbi,
    unsigned char * from, unsigned char * to)
{
    if (sbi->s_bytesex == BYTESEX_PDP) {
        to[0] = from[0];
        to[1] = 0;
        to[2] = from[1];
        to[3] = from[2];
    } else if (sbi->s_bytesex == BYTESEX_LE) {
        to[0] = from[0];
        to[1] = from[1];
        to[2] = from[2];
        to[3] = 0;
    } else {
        to[0] = 0;
        to[1] = from[0];
        to[2] = from[1];
        to[3] = from[2];
    }
}

static inline void write3byte(struct sysv_sb_info *sbi,
    unsigned char * from, unsigned char * to)
{
    if (sbi->s_bytesex == BYTESEX_PDP) {
        to[0] = from[0];
        to[1] = from[2];
        to[2] = from[3];
    } else if (sbi->s_bytesex == BYTESEX_LE) {
        to[0] = from[0];
        to[1] = from[1];
        to[2] = from[2];
    } else {
        to[0] = from[1];
        to[1] = from[2];
        to[2] = from[3];
    }
}

static const struct inode_operations sysv_symlink_inode_operations = {
    .readlink   = generic_readlink,
    .follow_link    = page_follow_link_light,
    .put_link   = page_put_link,
    .getattr    = sysv_getattr,
};

void sysv_set_inode(struct inode *inode, dev_t rdev)
{
    if (S_ISREG(inode->i_mode)) {
        inode->i_op = &sysv_file_inode_operations;
        inode->i_fop = &sysv_file_operations;
        inode->i_mapping->a_ops = &sysv_aops;
    } else if (S_ISDIR(inode->i_mode)) {
        inode->i_op = &sysv_dir_inode_operations;
        inode->i_fop = &sysv_dir_operations;
        inode->i_mapping->a_ops = &sysv_aops;
    } else if (S_ISLNK(inode->i_mode)) {
        if (inode->i_blocks) {
            inode->i_op = &sysv_symlink_inode_operations;
            inode->i_mapping->a_ops = &sysv_aops;
        } else {
            inode->i_op = &sysv_fast_symlink_inode_operations;
            nd_terminate_link(SYSV_I(inode)->i_data, inode->i_size,
                sizeof(SYSV_I(inode)->i_data) - 1);
        }
    } else
        init_special_inode(inode, inode->i_mode, rdev);
}

struct inode *sysv_iget(struct super_block *sb, unsigned int ino)
{
    struct sysv_sb_info * sbi = SYSV_SB(sb);
    struct buffer_head * bh;
    struct sysv_inode * raw_inode;
    struct sysv_inode_info * si;
    struct inode *inode;
    unsigned int block;

    if (!ino || ino > sbi->s_ninodes) {
        printk("Bad inode number on dev %s: %d is out of range\n",
               sb->s_id, ino);
        return ERR_PTR(-EIO);
    }

    inode = iget_locked(sb, ino);
    if (!inode)
        return ERR_PTR(-ENOMEM);
    if (!(inode->i_state & I_NEW))
        return inode;

    raw_inode = sysv_raw_inode(sb, ino, &bh);
    if (!raw_inode) {
        printk("Major problem: unable to read inode from dev %s\n",
               inode->i_sb->s_id);
        goto bad_inode;
    }
    /* SystemV FS: kludge permissions if ino==SYSV_ROOT_INO ?? */
    inode->i_mode = fs16_to_cpu(sbi, raw_inode->i_mode);
    i_uid_write(inode, (uid_t)fs16_to_cpu(sbi, raw_inode->i_uid));
    i_gid_write(inode, (gid_t)fs16_to_cpu(sbi, raw_inode->i_gid));
    set_nlink(inode, fs16_to_cpu(sbi, raw_inode->i_nlink));
    inode->i_size = fs32_to_cpu(sbi, raw_inode->i_size);
    inode->i_atime.tv_sec = fs32_to_cpu(sbi, raw_inode->i_atime);
    inode->i_mtime.tv_sec = fs32_to_cpu(sbi, raw_inode->i_mtime);
    inode->i_ctime.tv_sec = fs32_to_cpu(sbi, raw_inode->i_ctime);
    inode->i_ctime.tv_nsec = 0;
    inode->i_atime.tv_nsec = 0;
    inode->i_mtime.tv_nsec = 0;
    inode->i_blocks = 0;

    si = SYSV_I(inode);
    for (block = 0; block < 10+1+1+1; block++)
        read3byte(sbi, &raw_inode->i_data[3*block],
                (u8 *)&si->i_data[block]);
    brelse(bh);
    si->i_dir_start_lookup = 0;
    if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode))
        sysv_set_inode(inode,
                   old_decode_dev(fs32_to_cpu(sbi, si->i_data[0])));
    else
        sysv_set_inode(inode, 0);
    unlock_new_inode(inode);
    return inode;

bad_inode:
    iget_failed(inode);
    return ERR_PTR(-EIO);
}

static int __sysv_write_inode(struct inode *inode, int wait)
{
    struct super_block * sb = inode->i_sb;
    struct sysv_sb_info * sbi = SYSV_SB(sb);
    struct buffer_head * bh;
    struct sysv_inode * raw_inode;
    struct sysv_inode_info * si;
    unsigned int ino, block;
    int err = 0;

    ino = inode->i_ino;
    if (!ino || ino > sbi->s_ninodes) {
        printk("Bad inode number on dev %s: %d is out of range\n",
               inode->i_sb->s_id, ino);
        return -EIO;
    }
    raw_inode = sysv_raw_inode(sb, ino, &bh);
    if (!raw_inode) {
        printk("unable to read i-node block\n");
        return -EIO;
    }

    raw_inode->i_mode = cpu_to_fs16(sbi, inode->i_mode);
    raw_inode->i_uid = cpu_to_fs16(sbi, fs_high2lowuid(i_uid_read(inode)));
    raw_inode->i_gid = cpu_to_fs16(sbi, fs_high2lowgid(i_gid_read(inode)));
    raw_inode->i_nlink = cpu_to_fs16(sbi, inode->i_nlink);
    raw_inode->i_size = cpu_to_fs32(sbi, inode->i_size);
    raw_inode->i_atime = cpu_to_fs32(sbi, inode->i_atime.tv_sec);
    raw_inode->i_mtime = cpu_to_fs32(sbi, inode->i_mtime.tv_sec);
    raw_inode->i_ctime = cpu_to_fs32(sbi, inode->i_ctime.tv_sec);

    si = SYSV_I(inode);
    if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode))
        si->i_data[0] = cpu_to_fs32(sbi, old_encode_dev(inode->i_rdev));
    for (block = 0; block < 10+1+1+1; block++)
        write3byte(sbi, (u8 *)&si->i_data[block],
            &raw_inode->i_data[3*block]);
    mark_buffer_dirty(bh);
    if (wait) {
                sync_dirty_buffer(bh);
                if (buffer_req(bh) && !buffer_uptodate(bh)) {
                        printk ("IO error syncing sysv inode [%s:%08x]\n",
                                sb->s_id, ino);
                        err = -EIO;
                }
        }
    brelse(bh);
    return 0;
}

int sysv_write_inode(struct inode *inode, struct writeback_control *wbc)
{
    return __sysv_write_inode(inode, wbc->sync_mode == WB_SYNC_ALL);
}

int sysv_sync_inode(struct inode *inode)
{
    return __sysv_write_inode(inode, 1);
}

static void sysv_evict_inode(struct inode *inode)
{
    truncate_inode_pages(&inode->i_data, 0);
    if (!inode->i_nlink) {
        inode->i_size = 0;
        sysv_truncate(inode);
    }
    invalidate_inode_buffers(inode);
    clear_inode(inode);
    if (!inode->i_nlink)
        sysv_free_inode(inode);
}

static struct kmem_cache *sysv_inode_cachep;

static struct inode *sysv_alloc_inode(struct super_block *sb)
{
    struct sysv_inode_info *si;

    si = kmem_cache_alloc(sysv_inode_cachep, GFP_KERNEL);
    if (!si)
        return NULL;
    return &si->vfs_inode;
}

static void sysv_i_callback(struct rcu_head *head)
{
    struct inode *inode = container_of(head, struct inode, i_rcu);
    kmem_cache_free(sysv_inode_cachep, SYSV_I(inode));
}

static void sysv_destroy_inode(struct inode *inode)
{
    call_rcu(&inode->i_rcu, sysv_i_callback);
}

static void init_once(void *p)
{
    struct sysv_inode_info *si = (struct sysv_inode_info *)p;

    inode_init_once(&si->vfs_inode);
}

const struct super_operations sysv_sops = {
    .alloc_inode    = sysv_alloc_inode,
    .destroy_inode  = sysv_destroy_inode,
    .write_inode    = sysv_write_inode,
    .evict_inode    = sysv_evict_inode,
    .put_super  = sysv_put_super,
    .sync_fs    = sysv_sync_fs,
    .remount_fs = sysv_remount,
    .statfs     = sysv_statfs,
};

int __init sysv_init_icache(void)
{
    sysv_inode_cachep = kmem_cache_create("sysv_inode_cache",
            sizeof(struct sysv_inode_info), 0,
            SLAB_RECLAIM_ACCOUNT|SLAB_MEM_SPREAD,
            init_once);
    if (!sysv_inode_cachep)
        return -ENOMEM;
    return 0;
}

void sysv_destroy_icache(void)
{
    /*
     * Make sure all delayed rcu free inodes are flushed before we
     * destroy cache.
     */
    rcu_barrier();
    kmem_cache_destroy(sysv_inode_cachep);
}