dir.c

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/*
 * Copyright 2000 by Hans Reiser, licensing governed by reiserfs/README
 */

#include <linux/string.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include "reiserfs.h"
#include <linux/stat.h>
#include <linux/buffer_head.h>
#include <linux/slab.h>
#include <asm/uaccess.h>

extern const struct reiserfs_key MIN_KEY;

static int reiserfs_readdir(struct file *, void *, filldir_t);
static int reiserfs_dir_fsync(struct file *filp, loff_t start, loff_t end,
                  int datasync);

const struct file_operations reiserfs_dir_operations = {
    .llseek = generic_file_llseek,
    .read = generic_read_dir,
    .readdir = reiserfs_readdir,
    .fsync = reiserfs_dir_fsync,
    .unlocked_ioctl = reiserfs_ioctl,
#ifdef CONFIG_COMPAT
    .compat_ioctl = reiserfs_compat_ioctl,
#endif
};

static int reiserfs_dir_fsync(struct file *filp, loff_t start, loff_t end,
                  int datasync)
{
    struct inode *inode = filp->f_mapping->host;
    int err;

    err = filemap_write_and_wait_range(inode->i_mapping, start, end);
    if (err)
        return err;

    mutex_lock(&inode->i_mutex);
    reiserfs_write_lock(inode->i_sb);
    err = reiserfs_commit_for_inode(inode);
    reiserfs_write_unlock(inode->i_sb);
    mutex_unlock(&inode->i_mutex);
    if (err < 0)
        return err;
    return 0;
}

#define store_ih(where,what) copy_item_head (where, what)

static inline bool is_privroot_deh(struct dentry *dir,
                   struct reiserfs_de_head *deh)
{
    struct dentry *privroot = REISERFS_SB(dir->d_sb)->priv_root;
    return (dir == dir->d_parent && privroot->d_inode &&
            deh->deh_objectid == INODE_PKEY(privroot->d_inode)->k_objectid);
}

int reiserfs_readdir_dentry(struct dentry *dentry, void *dirent,
               filldir_t filldir, loff_t *pos)
{
    struct inode *inode = dentry->d_inode;
    struct cpu_key pos_key; /* key of current position in the directory (key of directory entry) */
    INITIALIZE_PATH(path_to_entry);
    struct buffer_head *bh;
    int item_num, entry_num;
    const struct reiserfs_key *rkey;
    struct item_head *ih, tmp_ih;
    int search_res;
    char *local_buf;
    loff_t next_pos;
    char small_buf[32]; /* avoid kmalloc if we can */
    struct reiserfs_dir_entry de;
    int ret = 0;

    reiserfs_write_lock(inode->i_sb);

    reiserfs_check_lock_depth(inode->i_sb, "readdir");

    /* form key for search the next directory entry using f_pos field of
       file structure */
    make_cpu_key(&pos_key, inode, *pos ?: DOT_OFFSET, TYPE_DIRENTRY, 3);
    next_pos = cpu_key_k_offset(&pos_key);

    path_to_entry.reada = PATH_READA;
    while (1) {
          research:
        /* search the directory item, containing entry with specified key */
        search_res =
            search_by_entry_key(inode->i_sb, &pos_key, &path_to_entry,
                    &de);
        if (search_res == IO_ERROR) {
            // FIXME: we could just skip part of directory which could
            // not be read
            ret = -EIO;
            goto out;
        }
        entry_num = de.de_entry_num;
        bh = de.de_bh;
        item_num = de.de_item_num;
        ih = de.de_ih;
        store_ih(&tmp_ih, ih);

        /* we must have found item, that is item of this directory, */
        RFALSE(COMP_SHORT_KEYS(&(ih->ih_key), &pos_key),
               "vs-9000: found item %h does not match to dir we readdir %K",
               ih, &pos_key);
        RFALSE(item_num > B_NR_ITEMS(bh) - 1,
               "vs-9005 item_num == %d, item amount == %d",
               item_num, B_NR_ITEMS(bh));

        /* and entry must be not more than number of entries in the item */
        RFALSE(I_ENTRY_COUNT(ih) < entry_num,
               "vs-9010: entry number is too big %d (%d)",
               entry_num, I_ENTRY_COUNT(ih));

        if (search_res == POSITION_FOUND
            || entry_num < I_ENTRY_COUNT(ih)) {
            /* go through all entries in the directory item beginning from the entry, that has been found */
            struct reiserfs_de_head *deh =
                B_I_DEH(bh, ih) + entry_num;

            for (; entry_num < I_ENTRY_COUNT(ih);
                 entry_num++, deh++) {
                int d_reclen;
                char *d_name;
                off_t d_off;
                ino_t d_ino;

                if (!de_visible(deh))
                    /* it is hidden entry */
                    continue;
                d_reclen = entry_length(bh, ih, entry_num);
                d_name = B_I_DEH_ENTRY_FILE_NAME(bh, ih, deh);

                if (d_reclen <= 0 ||
                    d_name + d_reclen > bh->b_data + bh->b_size) {
                    /* There is corrupted data in entry,
                     * We'd better stop here */
                    pathrelse(&path_to_entry);
                    ret = -EIO;
                    goto out;
                }

                if (!d_name[d_reclen - 1])
                    d_reclen = strlen(d_name);

                if (d_reclen >
                    REISERFS_MAX_NAME(inode->i_sb->
                              s_blocksize)) {
                    /* too big to send back to VFS */
                    continue;
                }

                /* Ignore the .reiserfs_priv entry */
                if (is_privroot_deh(dentry, deh))
                    continue;

                d_off = deh_offset(deh);
                *pos = d_off;
                d_ino = deh_objectid(deh);
                if (d_reclen <= 32) {
                    local_buf = small_buf;
                } else {
                    local_buf = kmalloc(d_reclen,
                                GFP_NOFS);
                    if (!local_buf) {
                        pathrelse(&path_to_entry);
                        ret = -ENOMEM;
                        goto out;
                    }
                    if (item_moved(&tmp_ih, &path_to_entry)) {
                        kfree(local_buf);
                        goto research;
                    }
                }
                // Note, that we copy name to user space via temporary
                // buffer (local_buf) because filldir will block if
                // user space buffer is swapped out. At that time
                // entry can move to somewhere else
                memcpy(local_buf, d_name, d_reclen);

                /*
                 * Since filldir might sleep, we can release
                 * the write lock here for other waiters
                 */
                reiserfs_write_unlock(inode->i_sb);
                if (filldir
                    (dirent, local_buf, d_reclen, d_off, d_ino,
                     DT_UNKNOWN) < 0) {
                    reiserfs_write_lock(inode->i_sb);
                    if (local_buf != small_buf) {
                        kfree(local_buf);
                    }
                    goto end;
                }
                reiserfs_write_lock(inode->i_sb);
                if (local_buf != small_buf) {
                    kfree(local_buf);
                }
                // next entry should be looked for with such offset
                next_pos = deh_offset(deh) + 1;

                if (item_moved(&tmp_ih, &path_to_entry)) {
                    goto research;
                }
            }   /* for */
        }

        if (item_num != B_NR_ITEMS(bh) - 1)
            // end of directory has been reached
            goto end;

        /* item we went through is last item of node. Using right
           delimiting key check is it directory end */
        rkey = get_rkey(&path_to_entry, inode->i_sb);
        if (!comp_le_keys(rkey, &MIN_KEY)) {
            /* set pos_key to key, that is the smallest and greater
               that key of the last entry in the item */
            set_cpu_key_k_offset(&pos_key, next_pos);
            continue;
        }

        if (COMP_SHORT_KEYS(rkey, &pos_key)) {
            // end of directory has been reached
            goto end;
        }

        /* directory continues in the right neighboring block */
        set_cpu_key_k_offset(&pos_key,
                     le_key_k_offset(KEY_FORMAT_3_5, rkey));

    }           /* while */

end:
    *pos = next_pos;
    pathrelse(&path_to_entry);
    reiserfs_check_path(&path_to_entry);
out:
    reiserfs_write_unlock(inode->i_sb);
    return ret;
}

static int reiserfs_readdir(struct file *file, void *dirent, filldir_t filldir)
{
    struct dentry *dentry = file->f_path.dentry;
    return reiserfs_readdir_dentry(dentry, dirent, filldir, &file->f_pos);
}

/* compose directory item containing "." and ".." entries (entries are
   not aligned to 4 byte boundary) */
/* the last four params are LE */
void make_empty_dir_item_v1(char *body, __le32 dirid, __le32 objid,
                __le32 par_dirid, __le32 par_objid)
{
    struct reiserfs_de_head *deh;

    memset(body, 0, EMPTY_DIR_SIZE_V1);
    deh = (struct reiserfs_de_head *)body;

    /* direntry header of "." */
    put_deh_offset(&(deh[0]), DOT_OFFSET);
    /* these two are from make_le_item_head, and are are LE */
    deh[0].deh_dir_id = dirid;
    deh[0].deh_objectid = objid;
    deh[0].deh_state = 0;   /* Endian safe if 0 */
    put_deh_location(&(deh[0]), EMPTY_DIR_SIZE_V1 - strlen("."));
    mark_de_visible(&(deh[0]));

    /* direntry header of ".." */
    put_deh_offset(&(deh[1]), DOT_DOT_OFFSET);
    /* key of ".." for the root directory */
    /* these two are from the inode, and are are LE */
    deh[1].deh_dir_id = par_dirid;
    deh[1].deh_objectid = par_objid;
    deh[1].deh_state = 0;   /* Endian safe if 0 */
    put_deh_location(&(deh[1]), deh_location(&(deh[0])) - strlen(".."));
    mark_de_visible(&(deh[1]));

    /* copy ".." and "." */
    memcpy(body + deh_location(&(deh[0])), ".", 1);
    memcpy(body + deh_location(&(deh[1])), "..", 2);
}

/* compose directory item containing "." and ".." entries */
void make_empty_dir_item(char *body, __le32 dirid, __le32 objid,
             __le32 par_dirid, __le32 par_objid)
{
    struct reiserfs_de_head *deh;

    memset(body, 0, EMPTY_DIR_SIZE);
    deh = (struct reiserfs_de_head *)body;

    /* direntry header of "." */
    put_deh_offset(&(deh[0]), DOT_OFFSET);
    /* these two are from make_le_item_head, and are are LE */
    deh[0].deh_dir_id = dirid;
    deh[0].deh_objectid = objid;
    deh[0].deh_state = 0;   /* Endian safe if 0 */
    put_deh_location(&(deh[0]), EMPTY_DIR_SIZE - ROUND_UP(strlen(".")));
    mark_de_visible(&(deh[0]));

    /* direntry header of ".." */
    put_deh_offset(&(deh[1]), DOT_DOT_OFFSET);
    /* key of ".." for the root directory */
    /* these two are from the inode, and are are LE */
    deh[1].deh_dir_id = par_dirid;
    deh[1].deh_objectid = par_objid;
    deh[1].deh_state = 0;   /* Endian safe if 0 */
    put_deh_location(&(deh[1]),
             deh_location(&(deh[0])) - ROUND_UP(strlen("..")));
    mark_de_visible(&(deh[1]));

    /* copy ".." and "." */
    memcpy(body + deh_location(&(deh[0])), ".", 1);
    memcpy(body + deh_location(&(deh[1])), "..", 2);
}