namei.c

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/*
 *  linux/fs/sysv/namei.c
 *
 *  minix/namei.c
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 *  coh/namei.c
 *  Copyright (C) 1993  Pascal Haible, Bruno Haible
 *
 *  sysv/namei.c
 *  Copyright (C) 1993  Bruno Haible
 *  Copyright (C) 1997, 1998  Krzysztof G. Baranowski
 */

#include <linux/pagemap.h>
#include "sysv.h"

static int add_nondir(struct dentry *dentry, struct inode *inode)
{
    int err = sysv_add_link(dentry, inode);
    if (!err) {
        d_instantiate(dentry, inode);
        return 0;
    }
    inode_dec_link_count(inode);
    iput(inode);
    return err;
}

static int sysv_hash(const struct dentry *dentry, const struct inode *inode,
        struct qstr *qstr)
{
    /* Truncate the name in place, avoids having to define a compare
       function. */
    if (qstr->len > SYSV_NAMELEN) {
        qstr->len = SYSV_NAMELEN;
        qstr->hash = full_name_hash(qstr->name, qstr->len);
    }
    return 0;
}

const struct dentry_operations sysv_dentry_operations = {
    .d_hash     = sysv_hash,
};

static struct dentry *sysv_lookup(struct inode * dir, struct dentry * dentry, unsigned int flags)
{
    struct inode * inode = NULL;
    ino_t ino;

    if (dentry->d_name.len > SYSV_NAMELEN)
        return ERR_PTR(-ENAMETOOLONG);
    ino = sysv_inode_by_name(dentry);

    if (ino) {
        inode = sysv_iget(dir->i_sb, ino);
        if (IS_ERR(inode))
            return ERR_CAST(inode);
    }
    d_add(dentry, inode);
    return NULL;
}

static int sysv_mknod(struct inode * dir, struct dentry * dentry, umode_t mode, dev_t rdev)
{
    struct inode * inode;
    int err;

    if (!old_valid_dev(rdev))
        return -EINVAL;

    inode = sysv_new_inode(dir, mode);
    err = PTR_ERR(inode);

    if (!IS_ERR(inode)) {
        sysv_set_inode(inode, rdev);
        mark_inode_dirty(inode);
        err = add_nondir(dentry, inode);
    }
    return err;
}

static int sysv_create(struct inode * dir, struct dentry * dentry, umode_t mode, bool excl)
{
    return sysv_mknod(dir, dentry, mode, 0);
}

static int sysv_symlink(struct inode * dir, struct dentry * dentry, 
    const char * symname)
{
    int err = -ENAMETOOLONG;
    int l = strlen(symname)+1;
    struct inode * inode;

    if (l > dir->i_sb->s_blocksize)
        goto out;

    inode = sysv_new_inode(dir, S_IFLNK|0777);
    err = PTR_ERR(inode);
    if (IS_ERR(inode))
        goto out;
    
    sysv_set_inode(inode, 0);
    err = page_symlink(inode, symname, l);
    if (err)
        goto out_fail;

    mark_inode_dirty(inode);
    err = add_nondir(dentry, inode);
out:
    return err;

out_fail:
    inode_dec_link_count(inode);
    iput(inode);
    goto out;
}

static int sysv_link(struct dentry * old_dentry, struct inode * dir, 
    struct dentry * dentry)
{
    struct inode *inode = old_dentry->d_inode;

    inode->i_ctime = CURRENT_TIME_SEC;
    inode_inc_link_count(inode);
    ihold(inode);

    return add_nondir(dentry, inode);
}

static int sysv_mkdir(struct inode * dir, struct dentry *dentry, umode_t mode)
{
    struct inode * inode;
    int err;

    inode_inc_link_count(dir);

    inode = sysv_new_inode(dir, S_IFDIR|mode);
    err = PTR_ERR(inode);
    if (IS_ERR(inode))
        goto out_dir;

    sysv_set_inode(inode, 0);

    inode_inc_link_count(inode);

    err = sysv_make_empty(inode, dir);
    if (err)
        goto out_fail;

    err = sysv_add_link(dentry, inode);
    if (err)
        goto out_fail;

        d_instantiate(dentry, inode);
out:
    return err;

out_fail:
    inode_dec_link_count(inode);
    inode_dec_link_count(inode);
    iput(inode);
out_dir:
    inode_dec_link_count(dir);
    goto out;
}

static int sysv_unlink(struct inode * dir, struct dentry * dentry)
{
    struct inode * inode = dentry->d_inode;
    struct page * page;
    struct sysv_dir_entry * de;
    int err = -ENOENT;

    de = sysv_find_entry(dentry, &page);
    if (!de)
        goto out;

    err = sysv_delete_entry (de, page);
    if (err)
        goto out;

    inode->i_ctime = dir->i_ctime;
    inode_dec_link_count(inode);
out:
    return err;
}

static int sysv_rmdir(struct inode * dir, struct dentry * dentry)
{
    struct inode *inode = dentry->d_inode;
    int err = -ENOTEMPTY;

    if (sysv_empty_dir(inode)) {
        err = sysv_unlink(dir, dentry);
        if (!err) {
            inode->i_size = 0;
            inode_dec_link_count(inode);
            inode_dec_link_count(dir);
        }
    }
    return err;
}

/*
 * Anybody can rename anything with this: the permission checks are left to the
 * higher-level routines.
 */
static int sysv_rename(struct inode * old_dir, struct dentry * old_dentry,
          struct inode * new_dir, struct dentry * new_dentry)
{
    struct inode * old_inode = old_dentry->d_inode;
    struct inode * new_inode = new_dentry->d_inode;
    struct page * dir_page = NULL;
    struct sysv_dir_entry * dir_de = NULL;
    struct page * old_page;
    struct sysv_dir_entry * old_de;
    int err = -ENOENT;

    old_de = sysv_find_entry(old_dentry, &old_page);
    if (!old_de)
        goto out;

    if (S_ISDIR(old_inode->i_mode)) {
        err = -EIO;
        dir_de = sysv_dotdot(old_inode, &dir_page);
        if (!dir_de)
            goto out_old;
    }

    if (new_inode) {
        struct page * new_page;
        struct sysv_dir_entry * new_de;

        err = -ENOTEMPTY;
        if (dir_de && !sysv_empty_dir(new_inode))
            goto out_dir;

        err = -ENOENT;
        new_de = sysv_find_entry(new_dentry, &new_page);
        if (!new_de)
            goto out_dir;
        sysv_set_link(new_de, new_page, old_inode);
        new_inode->i_ctime = CURRENT_TIME_SEC;
        if (dir_de)
            drop_nlink(new_inode);
        inode_dec_link_count(new_inode);
    } else {
        err = sysv_add_link(new_dentry, old_inode);
        if (err)
            goto out_dir;
        if (dir_de)
            inode_inc_link_count(new_dir);
    }

    sysv_delete_entry(old_de, old_page);
    mark_inode_dirty(old_inode);

    if (dir_de) {
        sysv_set_link(dir_de, dir_page, new_dir);
        inode_dec_link_count(old_dir);
    }
    return 0;

out_dir:
    if (dir_de) {
        kunmap(dir_page);
        page_cache_release(dir_page);
    }
out_old:
    kunmap(old_page);
    page_cache_release(old_page);
out:
    return err;
}

/*
 * directories can handle most operations...
 */
const struct inode_operations sysv_dir_inode_operations = {
    .create     = sysv_create,
    .lookup     = sysv_lookup,
    .link       = sysv_link,
    .unlink     = sysv_unlink,
    .symlink    = sysv_symlink,
    .mkdir      = sysv_mkdir,
    .rmdir      = sysv_rmdir,
    .mknod      = sysv_mknod,
    .rename     = sysv_rename,
    .getattr    = sysv_getattr,
};