namei.c

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/*
 * namei.c - NILFS pathname lookup operations.
 *
 * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 *
 * Modified for NILFS by Amagai Yoshiji <[email protected]>,
 *                       Ryusuke Konishi <[email protected]>
 */
/*
 *  linux/fs/ext2/namei.c
 *
 * Copyright (C) 1992, 1993, 1994, 1995
 * Remy Card ([email protected])
 * Laboratoire MASI - Institut Blaise Pascal
 * Universite Pierre et Marie Curie (Paris VI)
 *
 *  from
 *
 *  linux/fs/minix/namei.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 *  Big-endian to little-endian byte-swapping/bitmaps by
 *        David S. Miller ([email protected]), 1995
 */

#include <linux/pagemap.h>
#include "nilfs.h"
#include "export.h"

#define NILFS_FID_SIZE_NON_CONNECTABLE \
    (offsetof(struct nilfs_fid, parent_gen) / 4)
#define NILFS_FID_SIZE_CONNECTABLE  (sizeof(struct nilfs_fid) / 4)

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

/*
 * Methods themselves.
 */

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

    if (dentry->d_name.len > NILFS_NAME_LEN)
        return ERR_PTR(-ENAMETOOLONG);

    ino = nilfs_inode_by_name(dir, &dentry->d_name);
    inode = ino ? nilfs_iget(dir->i_sb, NILFS_I(dir)->i_root, ino) : NULL;
    return d_splice_alias(inode, dentry);
}

/*
 * By the time this is called, we already have created
 * the directory cache entry for the new file, but it
 * is so far negative - it has no inode.
 *
 * If the create succeeds, we fill in the inode information
 * with d_instantiate().
 */
static int nilfs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
            bool excl)
{
    struct inode *inode;
    struct nilfs_transaction_info ti;
    int err;

    err = nilfs_transaction_begin(dir->i_sb, &ti, 1);
    if (err)
        return err;
    inode = nilfs_new_inode(dir, mode);
    err = PTR_ERR(inode);
    if (!IS_ERR(inode)) {
        inode->i_op = &nilfs_file_inode_operations;
        inode->i_fop = &nilfs_file_operations;
        inode->i_mapping->a_ops = &nilfs_aops;
        nilfs_mark_inode_dirty(inode);
        err = nilfs_add_nondir(dentry, inode);
    }
    if (!err)
        err = nilfs_transaction_commit(dir->i_sb);
    else
        nilfs_transaction_abort(dir->i_sb);

    return err;
}

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

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

    err = nilfs_transaction_begin(dir->i_sb, &ti, 1);
    if (err)
        return err;
    inode = nilfs_new_inode(dir, mode);
    err = PTR_ERR(inode);
    if (!IS_ERR(inode)) {
        init_special_inode(inode, inode->i_mode, rdev);
        nilfs_mark_inode_dirty(inode);
        err = nilfs_add_nondir(dentry, inode);
    }
    if (!err)
        err = nilfs_transaction_commit(dir->i_sb);
    else
        nilfs_transaction_abort(dir->i_sb);

    return err;
}

static int nilfs_symlink(struct inode *dir, struct dentry *dentry,
             const char *symname)
{
    struct nilfs_transaction_info ti;
    struct super_block *sb = dir->i_sb;
    unsigned l = strlen(symname)+1;
    struct inode *inode;
    int err;

    if (l > sb->s_blocksize)
        return -ENAMETOOLONG;

    err = nilfs_transaction_begin(dir->i_sb, &ti, 1);
    if (err)
        return err;

    inode = nilfs_new_inode(dir, S_IFLNK | S_IRWXUGO);
    err = PTR_ERR(inode);
    if (IS_ERR(inode))
        goto out;

    /* slow symlink */
    inode->i_op = &nilfs_symlink_inode_operations;
    inode->i_mapping->a_ops = &nilfs_aops;
    err = page_symlink(inode, symname, l);
    if (err)
        goto out_fail;

    /* mark_inode_dirty(inode); */
    /* page_symlink() do this */

    err = nilfs_add_nondir(dentry, inode);
out:
    if (!err)
        err = nilfs_transaction_commit(dir->i_sb);
    else
        nilfs_transaction_abort(dir->i_sb);

    return err;

out_fail:
    drop_nlink(inode);
    nilfs_mark_inode_dirty(inode);
    iput(inode);
    goto out;
}

static int nilfs_link(struct dentry *old_dentry, struct inode *dir,
              struct dentry *dentry)
{
    struct inode *inode = old_dentry->d_inode;
    struct nilfs_transaction_info ti;
    int err;

    err = nilfs_transaction_begin(dir->i_sb, &ti, 1);
    if (err)
        return err;

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

    err = nilfs_add_nondir(dentry, inode);
    if (!err)
        err = nilfs_transaction_commit(dir->i_sb);
    else
        nilfs_transaction_abort(dir->i_sb);

    return err;
}

static int nilfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
{
    struct inode *inode;
    struct nilfs_transaction_info ti;
    int err;

    err = nilfs_transaction_begin(dir->i_sb, &ti, 1);
    if (err)
        return err;

    inc_nlink(dir);

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

    inode->i_op = &nilfs_dir_inode_operations;
    inode->i_fop = &nilfs_dir_operations;
    inode->i_mapping->a_ops = &nilfs_aops;

    inc_nlink(inode);

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

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

    nilfs_mark_inode_dirty(inode);
    d_instantiate(dentry, inode);
out:
    if (!err)
        err = nilfs_transaction_commit(dir->i_sb);
    else
        nilfs_transaction_abort(dir->i_sb);

    return err;

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

static int nilfs_do_unlink(struct inode *dir, struct dentry *dentry)
{
    struct inode *inode;
    struct nilfs_dir_entry *de;
    struct page *page;
    int err;

    err = -ENOENT;
    de = nilfs_find_entry(dir, &dentry->d_name, &page);
    if (!de)
        goto out;

    inode = dentry->d_inode;
    err = -EIO;
    if (le64_to_cpu(de->inode) != inode->i_ino)
        goto out;

    if (!inode->i_nlink) {
        nilfs_warning(inode->i_sb, __func__,
                  "deleting nonexistent file (%lu), %d\n",
                  inode->i_ino, inode->i_nlink);
        set_nlink(inode, 1);
    }
    err = nilfs_delete_entry(de, page);
    if (err)
        goto out;

    inode->i_ctime = dir->i_ctime;
    drop_nlink(inode);
    err = 0;
out:
    return err;
}

static int nilfs_unlink(struct inode *dir, struct dentry *dentry)
{
    struct nilfs_transaction_info ti;
    int err;

    err = nilfs_transaction_begin(dir->i_sb, &ti, 0);
    if (err)
        return err;

    err = nilfs_do_unlink(dir, dentry);

    if (!err) {
        nilfs_mark_inode_dirty(dir);
        nilfs_mark_inode_dirty(dentry->d_inode);
        err = nilfs_transaction_commit(dir->i_sb);
    } else
        nilfs_transaction_abort(dir->i_sb);

    return err;
}

static int nilfs_rmdir(struct inode *dir, struct dentry *dentry)
{
    struct inode *inode = dentry->d_inode;
    struct nilfs_transaction_info ti;
    int err;

    err = nilfs_transaction_begin(dir->i_sb, &ti, 0);
    if (err)
        return err;

    err = -ENOTEMPTY;
    if (nilfs_empty_dir(inode)) {
        err = nilfs_do_unlink(dir, dentry);
        if (!err) {
            inode->i_size = 0;
            drop_nlink(inode);
            nilfs_mark_inode_dirty(inode);
            drop_nlink(dir);
            nilfs_mark_inode_dirty(dir);
        }
    }
    if (!err)
        err = nilfs_transaction_commit(dir->i_sb);
    else
        nilfs_transaction_abort(dir->i_sb);

    return err;
}

static int nilfs_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 nilfs_dir_entry *dir_de = NULL;
    struct page *old_page;
    struct nilfs_dir_entry *old_de;
    struct nilfs_transaction_info ti;
    int err;

    err = nilfs_transaction_begin(old_dir->i_sb, &ti, 1);
    if (unlikely(err))
        return err;

    err = -ENOENT;
    old_de = nilfs_find_entry(old_dir, &old_dentry->d_name, &old_page);
    if (!old_de)
        goto out;

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

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

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

        err = -ENOENT;
        new_de = nilfs_find_entry(new_dir, &new_dentry->d_name, &new_page);
        if (!new_de)
            goto out_dir;
        nilfs_set_link(new_dir, new_de, new_page, old_inode);
        nilfs_mark_inode_dirty(new_dir);
        new_inode->i_ctime = CURRENT_TIME;
        if (dir_de)
            drop_nlink(new_inode);
        drop_nlink(new_inode);
        nilfs_mark_inode_dirty(new_inode);
    } else {
        err = nilfs_add_link(new_dentry, old_inode);
        if (err)
            goto out_dir;
        if (dir_de) {
            inc_nlink(new_dir);
            nilfs_mark_inode_dirty(new_dir);
        }
    }

    /*
     * Like most other Unix systems, set the ctime for inodes on a
     * rename.
     */
    old_inode->i_ctime = CURRENT_TIME;

    nilfs_delete_entry(old_de, old_page);

    if (dir_de) {
        nilfs_set_link(old_inode, dir_de, dir_page, new_dir);
        drop_nlink(old_dir);
    }
    nilfs_mark_inode_dirty(old_dir);
    nilfs_mark_inode_dirty(old_inode);

    err = nilfs_transaction_commit(old_dir->i_sb);
    return err;

out_dir:
    if (dir_de) {
        kunmap(dir_page);
        page_cache_release(dir_page);
    }
out_old:
    kunmap(old_page);
    page_cache_release(old_page);
out:
    nilfs_transaction_abort(old_dir->i_sb);
    return err;
}

/*
 * Export operations
 */
static struct dentry *nilfs_get_parent(struct dentry *child)
{
    unsigned long ino;
    struct inode *inode;
    struct qstr dotdot = QSTR_INIT("..", 2);
    struct nilfs_root *root;

    ino = nilfs_inode_by_name(child->d_inode, &dotdot);
    if (!ino)
        return ERR_PTR(-ENOENT);

    root = NILFS_I(child->d_inode)->i_root;

    inode = nilfs_iget(child->d_inode->i_sb, root, ino);
    if (IS_ERR(inode))
        return ERR_CAST(inode);

    return d_obtain_alias(inode);
}

static struct dentry *nilfs_get_dentry(struct super_block *sb, u64 cno,
                       u64 ino, u32 gen)
{
    struct nilfs_root *root;
    struct inode *inode;

    if (ino < NILFS_FIRST_INO(sb) && ino != NILFS_ROOT_INO)
        return ERR_PTR(-ESTALE);

    root = nilfs_lookup_root(sb->s_fs_info, cno);
    if (!root)
        return ERR_PTR(-ESTALE);

    inode = nilfs_iget(sb, root, ino);
    nilfs_put_root(root);

    if (IS_ERR(inode))
        return ERR_CAST(inode);
    if (gen && inode->i_generation != gen) {
        iput(inode);
        return ERR_PTR(-ESTALE);
    }
    return d_obtain_alias(inode);
}

static struct dentry *nilfs_fh_to_dentry(struct super_block *sb, struct fid *fh,
                     int fh_len, int fh_type)
{
    struct nilfs_fid *fid = (struct nilfs_fid *)fh;

    if ((fh_len != NILFS_FID_SIZE_NON_CONNECTABLE &&
         fh_len != NILFS_FID_SIZE_CONNECTABLE) ||
        (fh_type != FILEID_NILFS_WITH_PARENT &&
         fh_type != FILEID_NILFS_WITHOUT_PARENT))
        return NULL;

    return nilfs_get_dentry(sb, fid->cno, fid->ino, fid->gen);
}

static struct dentry *nilfs_fh_to_parent(struct super_block *sb, struct fid *fh,
                     int fh_len, int fh_type)
{
    struct nilfs_fid *fid = (struct nilfs_fid *)fh;

    if (fh_len != NILFS_FID_SIZE_CONNECTABLE ||
        fh_type != FILEID_NILFS_WITH_PARENT)
        return NULL;

    return nilfs_get_dentry(sb, fid->cno, fid->parent_ino, fid->parent_gen);
}

static int nilfs_encode_fh(struct inode *inode, __u32 *fh, int *lenp,
               struct inode *parent)
{
    struct nilfs_fid *fid = (struct nilfs_fid *)fh;
    struct nilfs_root *root = NILFS_I(inode)->i_root;
    int type;

    if (parent && *lenp < NILFS_FID_SIZE_CONNECTABLE) {
        *lenp = NILFS_FID_SIZE_CONNECTABLE;
        return 255;
    }
    if (*lenp < NILFS_FID_SIZE_NON_CONNECTABLE) {
        *lenp = NILFS_FID_SIZE_NON_CONNECTABLE;
        return 255;
    }

    fid->cno = root->cno;
    fid->ino = inode->i_ino;
    fid->gen = inode->i_generation;

    if (parent) {
        fid->parent_ino = parent->i_ino;
        fid->parent_gen = parent->i_generation;
        type = FILEID_NILFS_WITH_PARENT;
        *lenp = NILFS_FID_SIZE_CONNECTABLE;
    } else {
        type = FILEID_NILFS_WITHOUT_PARENT;
        *lenp = NILFS_FID_SIZE_NON_CONNECTABLE;
    }

    return type;
}

const struct inode_operations nilfs_dir_inode_operations = {
    .create     = nilfs_create,
    .lookup     = nilfs_lookup,
    .link       = nilfs_link,
    .unlink     = nilfs_unlink,
    .symlink    = nilfs_symlink,
    .mkdir      = nilfs_mkdir,
    .rmdir      = nilfs_rmdir,
    .mknod      = nilfs_mknod,
    .rename     = nilfs_rename,
    .setattr    = nilfs_setattr,
    .permission = nilfs_permission,
    .fiemap     = nilfs_fiemap,
};

const struct inode_operations nilfs_special_inode_operations = {
    .setattr    = nilfs_setattr,
    .permission = nilfs_permission,
};

const struct inode_operations nilfs_symlink_inode_operations = {
    .readlink   = generic_readlink,
    .follow_link    = page_follow_link_light,
    .put_link   = page_put_link,
    .permission     = nilfs_permission,
};

const struct export_operations nilfs_export_ops = {
    .encode_fh = nilfs_encode_fh,
    .fh_to_dentry = nilfs_fh_to_dentry,
    .fh_to_parent = nilfs_fh_to_parent,
    .get_parent = nilfs_get_parent,
};