Import 2.1.116pre2

[davej-history.git] / fs / ext2 / namei.c

/*
 *  linux/fs/ext2/namei.c
 *
 * Copyright (C) 1992, 1993, 1994, 1995
 * Remy Card (card@masi.ibp.fr)
 * 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 (davem@caip.rutgers.edu), 1995
 *  Directory entry file type support and forward compatibility hooks
 *      for B-tree directories by Theodore Ts'o (tytso@mit.edu), 1998
 */

#include <asm/uaccess.h>

#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/ext2_fs.h>
#include <linux/fcntl.h>
#include <linux/sched.h>
#include <linux/stat.h>
#include <linux/string.h>
#include <linux/locks.h>
#include <linux/quotaops.h>


/*
 * define how far ahead to read directories while searching them.
 */
#define NAMEI_RA_CHUNKS  2
#define NAMEI_RA_BLOCKS  4
#define NAMEI_RA_SIZE        (NAMEI_RA_CHUNKS * NAMEI_RA_BLOCKS)
#define NAMEI_RA_INDEX(c,b)  (((c) * NAMEI_RA_BLOCKS) + (b))

/*
 * NOTE! unlike strncmp, ext2_match returns 1 for success, 0 for failure.
 *
 * `len <= EXT2_NAME_LEN' is guaranteed by caller.
 * `de != NULL' is guaranteed by caller.
 */
static inline int ext2_match (int len, const char * const name,
                       struct ext2_dir_entry_2 * de)
{
        if (len != de->name_len)
                return 0;
        if (!de->inode)
                return 0;
        return !memcmp(name, de->name, len);
}

/*
 *      ext2_find_entry()
 *
 * finds an entry in the specified directory with the wanted name. It
 * returns the cache buffer in which the entry was found, and the entry
 * itself (as a parameter - res_dir). It does NOT read the inode of the
 * entry - you'll have to do that yourself if you want to.
 */
static struct buffer_head * ext2_find_entry (struct inode * dir,
                                             const char * const name, int namelen,
                                             struct ext2_dir_entry_2 ** res_dir)
{
        struct super_block * sb;
        struct buffer_head * bh_use[NAMEI_RA_SIZE];
        struct buffer_head * bh_read[NAMEI_RA_SIZE];
        unsigned long offset;
        int block, toread, i, err;

        *res_dir = NULL;
        if (!dir)
                return NULL;
        sb = dir->i_sb;

        if (namelen > EXT2_NAME_LEN)
                return NULL;

        memset (bh_use, 0, sizeof (bh_use));
        toread = 0;
        for (block = 0; block < NAMEI_RA_SIZE; ++block) {
                struct buffer_head * bh;

                if ((block << EXT2_BLOCK_SIZE_BITS (sb)) >= dir->i_size)
                        break;
                bh = ext2_getblk (dir, block, 0, &err);
                bh_use[block] = bh;
                if (bh && !buffer_uptodate(bh))
                        bh_read[toread++] = bh;
        }

        for (block = 0, offset = 0; offset < dir->i_size; block++) {
                struct buffer_head * bh;
                struct ext2_dir_entry_2 * de;
                char * dlimit;

                if ((block % NAMEI_RA_BLOCKS) == 0 && toread) {
                        ll_rw_block (READ, toread, bh_read);
                        toread = 0;
                }
                bh = bh_use[block % NAMEI_RA_SIZE];
                if (!bh) {
#if 0
                        ext2_error (sb, "ext2_find_entry",
                                    "directory #%lu contains a hole at offset %lu",
                                    dir->i_ino, offset);
#endif
                        offset += sb->s_blocksize;
                        continue;
                }
                wait_on_buffer (bh);
                if (!buffer_uptodate(bh)) {
                        /*
                         * read error: all bets are off
                         */
                        break;
                }

                de = (struct ext2_dir_entry_2 *) bh->b_data;
                dlimit = bh->b_data + sb->s_blocksize;
                while ((char *) de < dlimit) {
                        /* this code is executed quadratically often */
                        /* do minimal checking `by hand' */
                        int de_len;

                        if ((char *) de + namelen <= dlimit &&
                            ext2_match (namelen, name, de)) {
                                /* found a match -
                                   just to be sure, do a full check */
                                if (!ext2_check_dir_entry("ext2_find_entry",
                                                          dir, de, bh, offset))
                                        goto failure;
                                for (i = 0; i < NAMEI_RA_SIZE; ++i) {
                                        if (bh_use[i] != bh)
                                                brelse (bh_use[i]);
                                }
                                *res_dir = de;
                                return bh;
                        }
                        /* prevent looping on a bad block */
                        de_len = le16_to_cpu(de->rec_len);
                        if (de_len <= 0)
                                goto failure;
                        offset += de_len;
                        de = (struct ext2_dir_entry_2 *)
                                ((char *) de + de_len);
                }

                brelse (bh);
                if (((block + NAMEI_RA_SIZE) << EXT2_BLOCK_SIZE_BITS (sb)) >=
                    dir->i_size)
                        bh = NULL;
                else
                        bh = ext2_getblk (dir, block + NAMEI_RA_SIZE, 0, &err);
                bh_use[block % NAMEI_RA_SIZE] = bh;
                if (bh && !buffer_uptodate(bh))
                        bh_read[toread++] = bh;
        }

failure:
        for (i = 0; i < NAMEI_RA_SIZE; ++i)
                brelse (bh_use[i]);
        return NULL;
}

int ext2_lookup(struct inode * dir, struct dentry *dentry)
{
        struct inode * inode;
        struct ext2_dir_entry_2 * de;
        struct buffer_head * bh;

        if (dentry->d_name.len > EXT2_NAME_LEN)
                return -ENAMETOOLONG;

        bh = ext2_find_entry (dir, dentry->d_name.name, dentry->d_name.len, &de);
        inode = NULL;
        if (bh) {
                unsigned long ino = le32_to_cpu(de->inode);
                brelse (bh);
                inode = iget(dir->i_sb, ino);

                if (!inode)
                        return -EACCES;
        }
        d_add(dentry, inode);
        return 0;
}

/*
 *      ext2_add_entry()
 *
 * adds a file entry to the specified directory, using the same
 * semantics as ext2_find_entry(). It returns NULL if it failed.
 *
 * NOTE!! The inode part of 'de' is left at 0 - which means you
 * may not sleep between calling this and putting something into
 * the entry, as someone else might have used it while you slept.
 */
static struct buffer_head * ext2_add_entry (struct inode * dir,
                                            const char * name, int namelen,
                                            struct ext2_dir_entry_2 ** res_dir,
                                            int *err)
{
        unsigned long offset;
        unsigned short rec_len;
        struct buffer_head * bh;
        struct ext2_dir_entry_2 * de, * de1;
        struct super_block * sb;

        *err = -EINVAL;
        *res_dir = NULL;
        if (!dir || !dir->i_nlink)
                return NULL;
        sb = dir->i_sb;

        if (namelen > EXT2_NAME_LEN)
        {
                *err = -ENAMETOOLONG;
                return NULL;
        }

        if (!namelen)
                return NULL;
        /*
         * Is this a busy deleted directory?  Can't create new files if so
         */
        if (dir->i_size == 0)
        {
                *err = -ENOENT;
                return NULL;
        }
        bh = ext2_bread (dir, 0, 0, err);
        if (!bh)
                return NULL;
        rec_len = EXT2_DIR_REC_LEN(namelen);
        offset = 0;
        de = (struct ext2_dir_entry_2 *) bh->b_data;
        *err = -ENOSPC;
        while (1) {
                if ((char *)de >= sb->s_blocksize + bh->b_data) {
                        brelse (bh);
                        bh = NULL;
                        bh = ext2_bread (dir, offset >> EXT2_BLOCK_SIZE_BITS(sb), 1, err);
                        if (!bh)
                                return NULL;
                        if (dir->i_size <= offset) {
                                if (dir->i_size == 0) {
                                        *err = -ENOENT;
                                        return NULL;
                                }

                                ext2_debug ("creating next block\n");

                                de = (struct ext2_dir_entry_2 *) bh->b_data;
                                de->inode = le32_to_cpu(0);
                                de->rec_len = le16_to_cpu(sb->s_blocksize);
                                dir->i_size = offset + sb->s_blocksize;
                                dir->u.ext2_i.i_flags &= ~EXT2_BTREE_FL;
                                mark_inode_dirty(dir);
                        } else {

                                ext2_debug ("skipping to next block\n");

                                de = (struct ext2_dir_entry_2 *) bh->b_data;
                        }
                }
                if (!ext2_check_dir_entry ("ext2_add_entry", dir, de, bh,
                                           offset)) {
                        *err = -ENOENT;
                        brelse (bh);
                        return NULL;
                }
                if (ext2_match (namelen, name, de)) {
                                *err = -EEXIST;
                                brelse (bh);
                                return NULL;
                }
                if ((le32_to_cpu(de->inode) == 0 && le16_to_cpu(de->rec_len) >= rec_len) ||
                    (le16_to_cpu(de->rec_len) >= EXT2_DIR_REC_LEN(de->name_len) + rec_len)) {
                        offset += le16_to_cpu(de->rec_len);
                        if (le32_to_cpu(de->inode)) {
                                de1 = (struct ext2_dir_entry_2 *) ((char *) de +
                                        EXT2_DIR_REC_LEN(de->name_len));
                                de1->rec_len = cpu_to_le16(le16_to_cpu(de->rec_len) -
                                        EXT2_DIR_REC_LEN(de->name_len));
                                de->rec_len = cpu_to_le16(EXT2_DIR_REC_LEN(de->name_len));
                                de = de1;
                        }
                        de->inode = cpu_to_le32(0);
                        de->name_len = namelen;
                        de->file_type = 0;
                        memcpy (de->name, name, namelen);
                        /*
                         * XXX shouldn't update any times until successful
                         * completion of syscall, but too many callers depend
                         * on this.
                         *
                         * XXX similarly, too many callers depend on
                         * ext2_new_inode() setting the times, but error
                         * recovery deletes the inode, so the worst that can
                         * happen is that the times are slightly out of date
                         * and/or different from the directory change time.
                         */
                        dir->i_mtime = dir->i_ctime = CURRENT_TIME;
                        dir->u.ext2_i.i_flags &= ~EXT2_BTREE_FL;
                        mark_inode_dirty(dir);
                        dir->i_version = ++event;
                        mark_buffer_dirty(bh, 1);
                        *res_dir = de;
                        *err = 0;
                        return bh;
                }
                offset += le16_to_cpu(de->rec_len);
                de = (struct ext2_dir_entry_2 *) ((char *) de + le16_to_cpu(de->rec_len));
        }
        brelse (bh);
        return NULL;
}

/*
 * ext2_delete_entry deletes a directory entry by merging it with the
 * previous entry
 */
static int ext2_delete_entry (struct ext2_dir_entry_2 * dir,
                              struct buffer_head * bh)
{
        struct ext2_dir_entry_2 * de, * pde;
        int i;

        i = 0;
        pde = NULL;
        de = (struct ext2_dir_entry_2 *) bh->b_data;
        while (i < bh->b_size) {
                if (!ext2_check_dir_entry ("ext2_delete_entry", NULL, 
                                           de, bh, i))
                        return -EIO;
                if (de == dir)  {
                        if (pde)
                                pde->rec_len =
                                        cpu_to_le16(le16_to_cpu(pde->rec_len) +
                                                    le16_to_cpu(dir->rec_len));
                        dir->inode = le32_to_cpu(0);
                        return 0;
                }
                i += le16_to_cpu(de->rec_len);
                pde = de;
                de = (struct ext2_dir_entry_2 *) ((char *) de + le16_to_cpu(de->rec_len));
        }
        return -ENOENT;
}

/*
 * 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(). 
 */
int ext2_create (struct inode * dir, struct dentry * dentry, int mode)
{
        struct inode * inode;
        struct buffer_head * bh;
        struct ext2_dir_entry_2 * de;
        int err = -EIO;

        /*
         * N.B. Several error exits in ext2_new_inode don't set err.
         */
        inode = ext2_new_inode (dir, mode, &err);
        if (!inode)
                return err;

        inode->i_op = &ext2_file_inode_operations;
        inode->i_mode = mode;
        mark_inode_dirty(inode);
        bh = ext2_add_entry (dir, dentry->d_name.name, dentry->d_name.len, &de, &err);
        if (!bh) {
                inode->i_nlink--;
                mark_inode_dirty(inode);
                iput (inode);
                return err;
        }
        de->inode = cpu_to_le32(inode->i_ino);
        if (EXT2_HAS_INCOMPAT_FEATURE(dir->i_sb,
                                      EXT2_FEATURE_INCOMPAT_FILETYPE))
                de->file_type = EXT2_FT_REG_FILE;
        dir->i_version = ++event;
        mark_buffer_dirty(bh, 1);
        if (IS_SYNC(dir)) {
                ll_rw_block (WRITE, 1, &bh);
                wait_on_buffer (bh);
        }
        brelse (bh);
        d_instantiate(dentry, inode);
        return 0;
}

int ext2_mknod (struct inode * dir, struct dentry *dentry, int mode, int rdev)
{
        struct inode * inode;
        struct buffer_head * bh;
        struct ext2_dir_entry_2 * de;
        int err = -EIO;

        err = -ENAMETOOLONG;
        if (dentry->d_name.len > EXT2_NAME_LEN)
                goto out;

        inode = ext2_new_inode (dir, mode, &err);
        if (!inode)
                goto out;

        inode->i_uid = current->fsuid;
        inode->i_mode = mode;
        inode->i_op = NULL;
        bh = ext2_add_entry (dir, dentry->d_name.name, dentry->d_name.len, &de, &err);
        if (!bh)
                goto out_no_entry;
        de->inode = cpu_to_le32(inode->i_ino);
        dir->i_version = ++event;
        if (S_ISREG(inode->i_mode)) {
                inode->i_op = &ext2_file_inode_operations;
                if (EXT2_HAS_INCOMPAT_FEATURE(dir->i_sb,
                                              EXT2_FEATURE_INCOMPAT_FILETYPE))
                        de->file_type = EXT2_FT_REG_FILE;
        } else if (S_ISDIR(inode->i_mode)) {
                inode->i_op = &ext2_dir_inode_operations;
                if (dir->i_mode & S_ISGID)
                        inode->i_mode |= S_ISGID;
                if (EXT2_HAS_INCOMPAT_FEATURE(dir->i_sb,
                                              EXT2_FEATURE_INCOMPAT_FILETYPE))
                        de->file_type = EXT2_FT_DIR;
        }
        else if (S_ISLNK(inode->i_mode)) {
                inode->i_op = &ext2_symlink_inode_operations;
                if (EXT2_HAS_INCOMPAT_FEATURE(dir->i_sb,
                                              EXT2_FEATURE_INCOMPAT_FILETYPE))
                        de->file_type = EXT2_FT_SYMLINK;
        } else if (S_ISCHR(inode->i_mode)) {
                inode->i_op = &chrdev_inode_operations;
                if (EXT2_HAS_INCOMPAT_FEATURE(dir->i_sb,
                                              EXT2_FEATURE_INCOMPAT_FILETYPE))
                        de->file_type = EXT2_FT_CHRDEV;
        } else if (S_ISBLK(inode->i_mode)) {
                inode->i_op = &blkdev_inode_operations;
                if (EXT2_HAS_INCOMPAT_FEATURE(dir->i_sb,
                                              EXT2_FEATURE_INCOMPAT_FILETYPE))
                        de->file_type = EXT2_FT_BLKDEV;
        } else if (S_ISFIFO(inode->i_mode))  {
                init_fifo(inode);
                if (EXT2_HAS_INCOMPAT_FEATURE(dir->i_sb,
                                              EXT2_FEATURE_INCOMPAT_FILETYPE))
                        de->file_type = EXT2_FT_FIFO;
        }
        if (S_ISBLK(mode) || S_ISCHR(mode))
                inode->i_rdev = to_kdev_t(rdev);
        mark_inode_dirty(inode);
        mark_buffer_dirty(bh, 1);
        if (IS_SYNC(dir)) {
                ll_rw_block (WRITE, 1, &bh);
                wait_on_buffer (bh);
        }
        d_instantiate(dentry, inode);
        brelse(bh);
        err = 0;
out:
        return err;

out_no_entry:
        inode->i_nlink--;
        mark_inode_dirty(inode);
        iput(inode);
        goto out;
}

int ext2_mkdir(struct inode * dir, struct dentry * dentry, int mode)
{
        struct inode * inode;
        struct buffer_head * bh, * dir_block;
        struct ext2_dir_entry_2 * de;
        int err;

        err = -ENAMETOOLONG;
        if (dentry->d_name.len > EXT2_NAME_LEN)
                goto out;

        err = -EMLINK;
        if (dir->i_nlink >= EXT2_LINK_MAX)
                goto out;

        err = -EIO;
        inode = ext2_new_inode (dir, S_IFDIR, &err);
        if (!inode)
                goto out;

        inode->i_op = &ext2_dir_inode_operations;
        inode->i_size = inode->i_sb->s_blocksize;
        inode->i_blocks = 0;    
        dir_block = ext2_bread (inode, 0, 1, &err);
        if (!dir_block) {
                inode->i_nlink--; /* is this nlink == 0? */
                mark_inode_dirty(inode);
                iput (inode);
                return err;
        }
        de = (struct ext2_dir_entry_2 *) dir_block->b_data;
        de->inode = cpu_to_le32(inode->i_ino);
        de->name_len = 1;
        de->rec_len = cpu_to_le16(EXT2_DIR_REC_LEN(de->name_len));
        strcpy (de->name, ".");
        if (EXT2_HAS_INCOMPAT_FEATURE(dir->i_sb,
                                      EXT2_FEATURE_INCOMPAT_FILETYPE))
                de->file_type = EXT2_FT_DIR;
        de = (struct ext2_dir_entry_2 *) ((char *) de + le16_to_cpu(de->rec_len));
        de->inode = cpu_to_le32(dir->i_ino);
        de->rec_len = cpu_to_le16(inode->i_sb->s_blocksize - EXT2_DIR_REC_LEN(1));
        de->name_len = 2;
        strcpy (de->name, "..");
        if (EXT2_HAS_INCOMPAT_FEATURE(dir->i_sb,
                                      EXT2_FEATURE_INCOMPAT_FILETYPE))
                de->file_type = EXT2_FT_DIR;
        inode->i_nlink = 2;
        mark_buffer_dirty(dir_block, 1);
        brelse (dir_block);
        inode->i_mode = S_IFDIR | (mode & (S_IRWXUGO|S_ISVTX) & ~current->fs->umask);
        if (dir->i_mode & S_ISGID)
                inode->i_mode |= S_ISGID;
        mark_inode_dirty(inode);
        bh = ext2_add_entry (dir, dentry->d_name.name, dentry->d_name.len, &de, &err);
        if (!bh)
                goto out_no_entry;
        de->inode = cpu_to_le32(inode->i_ino);
        if (EXT2_HAS_INCOMPAT_FEATURE(dir->i_sb,
                                      EXT2_FEATURE_INCOMPAT_FILETYPE))
                de->file_type = EXT2_FT_DIR;
        dir->i_version = ++event;
        mark_buffer_dirty(bh, 1);
        if (IS_SYNC(dir)) {
                ll_rw_block (WRITE, 1, &bh);
                wait_on_buffer (bh);
        }
        dir->i_nlink++;
        dir->u.ext2_i.i_flags &= ~EXT2_BTREE_FL;
        mark_inode_dirty(dir);
        d_instantiate(dentry, inode);
        brelse (bh);
        err = 0;
out:
        return err;

out_no_entry:
        inode->i_nlink = 0;
        mark_inode_dirty(inode);
        iput (inode);
        goto out;
}

/*
 * routine to check that the specified directory is empty (for rmdir)
 */
static int empty_dir (struct inode * inode)
{
        unsigned long offset;
        struct buffer_head * bh;
        struct ext2_dir_entry_2 * de, * de1;
        struct super_block * sb;
        int err;

        sb = inode->i_sb;
        if (inode->i_size < EXT2_DIR_REC_LEN(1) + EXT2_DIR_REC_LEN(2) ||
            !(bh = ext2_bread (inode, 0, 0, &err))) {
                ext2_warning (inode->i_sb, "empty_dir",
                              "bad directory (dir #%lu) - no data block",
                              inode->i_ino);
                return 1;
        }
        de = (struct ext2_dir_entry_2 *) bh->b_data;
        de1 = (struct ext2_dir_entry_2 *) ((char *) de + le16_to_cpu(de->rec_len));
        if (le32_to_cpu(de->inode) != inode->i_ino || !le32_to_cpu(de1->inode) || 
            strcmp (".", de->name) || strcmp ("..", de1->name)) {
                ext2_warning (inode->i_sb, "empty_dir",
                              "bad directory (dir #%lu) - no `.' or `..'",
                              inode->i_ino);
                brelse (bh);
                return 1;
        }
        offset = le16_to_cpu(de->rec_len) + le16_to_cpu(de1->rec_len);
        de = (struct ext2_dir_entry_2 *) ((char *) de1 + le16_to_cpu(de1->rec_len));
        while (offset < inode->i_size ) {
                if (!bh || (void *) de >= (void *) (bh->b_data + sb->s_blocksize)) {
                        brelse (bh);
                        bh = ext2_bread (inode, offset >> EXT2_BLOCK_SIZE_BITS(sb), 1, &err);
                        if (!bh) {
#if 0
                                ext2_error (sb, "empty_dir",
                                            "directory #%lu contains a hole at offset %lu",
                                            inode->i_ino, offset);
#endif
                                offset += sb->s_blocksize;
                                continue;
                        }
                        de = (struct ext2_dir_entry_2 *) bh->b_data;
                }
                if (!ext2_check_dir_entry ("empty_dir", inode, de, bh,
                                           offset)) {
                        brelse (bh);
                        return 1;
                }
                if (le32_to_cpu(de->inode)) {
                        brelse (bh);
                        return 0;
                }
                offset += le16_to_cpu(de->rec_len);
                de = (struct ext2_dir_entry_2 *) ((char *) de + le16_to_cpu(de->rec_len));
        }
        brelse (bh);
        return 1;
}

int ext2_rmdir (struct inode * dir, struct dentry *dentry)
{
        int retval;
        struct inode * inode;
        struct buffer_head * bh;
        struct ext2_dir_entry_2 * de;

        retval = -ENAMETOOLONG;
        if (dentry->d_name.len > EXT2_NAME_LEN)
                goto out;

        retval = -ENOENT;
        bh = ext2_find_entry (dir, dentry->d_name.name, dentry->d_name.len, &de);
        if (!bh)
                goto end_rmdir;

        inode = dentry->d_inode;
        DQUOT_INIT(inode);

        retval = -EPERM;
        if ((dir->i_mode & S_ISVTX) && 
            current->fsuid != inode->i_uid &&
            current->fsuid != dir->i_uid && !capable(CAP_FOWNER))
                goto end_rmdir;
        if (inode == dir)       /* we may not delete ".", but "../dir" is ok */
                goto end_rmdir;

        retval = -ENOTDIR;
        if (!S_ISDIR(inode->i_mode))
                goto end_rmdir;

        retval = -EIO;
        if (inode->i_dev != dir->i_dev)
                goto end_rmdir;
        if (le32_to_cpu(de->inode) != inode->i_ino)
                goto end_rmdir;

        down(&inode->i_sem);
        /*
         * Prune any child dentries so that this dentry becomes negative.
         */
        if (dentry->d_count > 1)
                shrink_dcache_parent(dentry);

        if (!empty_dir (inode))
                retval = -ENOTEMPTY;
        else if (le32_to_cpu(de->inode) != inode->i_ino)
                retval = -ENOENT;
        else {
                if (dentry->d_count > 1) {
                /*
                 * Are we deleting the last instance of a busy directory?
                 * Better clean up if so.
                 *
                 * Make directory empty (it will be truncated when finally
                 * dereferenced).  This also inhibits ext2_add_entry.
                 */
                        inode->i_size = 0;
                }
                retval = ext2_delete_entry (de, bh);
                dir->i_version = ++event;
        }
        up(&inode->i_sem);
        if (retval)
                goto end_rmdir;
        mark_buffer_dirty(bh, 1);
        if (IS_SYNC(dir)) {
                ll_rw_block (WRITE, 1, &bh);
                wait_on_buffer (bh);
        }
        if (inode->i_nlink != 2)
                ext2_warning (inode->i_sb, "ext2_rmdir",
                              "empty directory has nlink!=2 (%d)",
                              inode->i_nlink);
        inode->i_version = ++event;
        inode->i_nlink = 0;
        mark_inode_dirty(inode);
        dir->i_nlink--;
        inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
        dir->u.ext2_i.i_flags &= ~EXT2_BTREE_FL;
        mark_inode_dirty(dir);
        d_delete(dentry);

end_rmdir:
        brelse (bh);
out:
        return retval;
}

int ext2_unlink(struct inode * dir, struct dentry *dentry)
{
        int retval;
        struct inode * inode;
        struct buffer_head * bh;
        struct ext2_dir_entry_2 * de;

        retval = -ENAMETOOLONG;
        if (dentry->d_name.len > EXT2_NAME_LEN)
                goto out;

        retval = -ENOENT;
        bh = ext2_find_entry (dir, dentry->d_name.name, dentry->d_name.len, &de);
        if (!bh)
                goto end_unlink;

        inode = dentry->d_inode;
        DQUOT_INIT(inode);

        retval = -EPERM;
        if (S_ISDIR(inode->i_mode))
                goto end_unlink;
        if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
                goto end_unlink;
        if ((dir->i_mode & S_ISVTX) &&
            current->fsuid != inode->i_uid &&
            current->fsuid != dir->i_uid && !capable(CAP_FOWNER))
                goto end_unlink;

        retval = -EIO;
        if (le32_to_cpu(de->inode) != inode->i_ino)
                goto end_unlink;
        
        if (!inode->i_nlink) {
                ext2_warning (inode->i_sb, "ext2_unlink",
                              "Deleting nonexistent file (%lu), %d",
                              inode->i_ino, inode->i_nlink);
                inode->i_nlink = 1;
        }
        retval = ext2_delete_entry (de, bh);
        if (retval)
                goto end_unlink;
        dir->i_version = ++event;
        mark_buffer_dirty(bh, 1);
        if (IS_SYNC(dir)) {
                ll_rw_block (WRITE, 1, &bh);
                wait_on_buffer (bh);
        }
        dir->i_ctime = dir->i_mtime = CURRENT_TIME;
        dir->u.ext2_i.i_flags &= ~EXT2_BTREE_FL;
        mark_inode_dirty(dir);
        inode->i_nlink--;
        mark_inode_dirty(inode);
        inode->i_ctime = dir->i_ctime;
        retval = 0;
        d_delete(dentry);       /* This also frees the inode */

end_unlink:
        brelse (bh);
out:
        return retval;
}

int ext2_symlink (struct inode * dir, struct dentry *dentry, const char * symname)
{
        struct ext2_dir_entry_2 * de;
        struct inode * inode;
        struct buffer_head * bh = NULL, * name_block = NULL;
        char * link;
        int i, l, err = -EIO;
        char c;

        if (!(inode = ext2_new_inode (dir, S_IFLNK, &err))) {
                return err;
        }
        inode->i_mode = S_IFLNK | S_IRWXUGO;
        inode->i_op = &ext2_symlink_inode_operations;
        for (l = 0; l < inode->i_sb->s_blocksize - 1 &&
             symname [l]; l++)
                ;
        if (l >= sizeof (inode->u.ext2_i.i_data)) {

                ext2_debug ("l=%d, normal symlink\n", l);

                name_block = ext2_bread (inode, 0, 1, &err);
                if (!name_block) {
                        inode->i_nlink--;
                        mark_inode_dirty(inode);
                        iput (inode);
                        return err;
                }
                link = name_block->b_data;
        } else {
                link = (char *) inode->u.ext2_i.i_data;

                ext2_debug ("l=%d, fast symlink\n", l);

        }
        i = 0;
        while (i < inode->i_sb->s_blocksize - 1 && (c = *(symname++)))
                link[i++] = c;
        link[i] = 0;
        if (name_block) {
                mark_buffer_dirty(name_block, 1);
                brelse (name_block);
        }
        inode->i_size = i;
        mark_inode_dirty(inode);

        bh = ext2_add_entry (dir, dentry->d_name.name, dentry->d_name.len, &de, &err);
        if (!bh)
                goto out_no_entry;
        de->inode = cpu_to_le32(inode->i_ino);
        if (EXT2_HAS_INCOMPAT_FEATURE(dir->i_sb,
                                      EXT2_FEATURE_INCOMPAT_FILETYPE))
                de->file_type = EXT2_FT_SYMLINK;
        dir->i_version = ++event;
        mark_buffer_dirty(bh, 1);
        if (IS_SYNC(dir)) {
                ll_rw_block (WRITE, 1, &bh);
                wait_on_buffer (bh);
        }
        brelse (bh);
        d_instantiate(dentry, inode);
        err = 0;
out:
        return err;

out_no_entry:
        inode->i_nlink--;
        mark_inode_dirty(inode);
        iput (inode);
        goto out;
}

int ext2_link (struct dentry * old_dentry,
                struct inode * dir, struct dentry *dentry)
{
        struct inode *inode = old_dentry->d_inode;
        struct ext2_dir_entry_2 * de;
        struct buffer_head * bh;
        int err;

        if (S_ISDIR(inode->i_mode))
                return -EPERM;

        if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
                return -EPERM;

        if (inode->i_nlink >= EXT2_LINK_MAX)
                return -EMLINK;

        bh = ext2_add_entry (dir, dentry->d_name.name, dentry->d_name.len, &de, &err);
        if (!bh)
                return err;

        de->inode = cpu_to_le32(inode->i_ino);
        if (EXT2_HAS_INCOMPAT_FEATURE(inode->i_sb,
                                      EXT2_FEATURE_INCOMPAT_FILETYPE)) {
                if (S_ISREG(inode->i_mode))
                        de->file_type = EXT2_FT_REG_FILE;
                else if (S_ISDIR(inode->i_mode))
                        de->file_type = EXT2_FT_DIR;
                else if (S_ISLNK(inode->i_mode))
                        de->file_type = EXT2_FT_SYMLINK;
                else if (S_ISCHR(inode->i_mode))
                        de->file_type = EXT2_FT_CHRDEV;
                else if (S_ISBLK(inode->i_mode))
                        de->file_type = EXT2_FT_BLKDEV;
                else if (S_ISFIFO(inode->i_mode))  
                        de->file_type = EXT2_FT_FIFO;
        }
        dir->i_version = ++event;
        mark_buffer_dirty(bh, 1);
        if (IS_SYNC(dir)) {
                ll_rw_block (WRITE, 1, &bh);
                wait_on_buffer (bh);
        }
        brelse (bh);
        inode->i_nlink++;
        inode->i_ctime = CURRENT_TIME;
        mark_inode_dirty(inode);
        inode->i_count++;
        d_instantiate(dentry, inode);
        return 0;
}

#define PARENT_INO(buffer) \
        ((struct ext2_dir_entry_2 *) ((char *) buffer + \
        le16_to_cpu(((struct ext2_dir_entry_2 *) buffer)->rec_len)))->inode

/*
 * rename uses retrying to avoid race-conditions: at least they should be
 * minimal.
 * it tries to allocate all the blocks, then sanity-checks, and if the sanity-
 * checks fail, it tries to restart itself again. Very practical - no changes
 * are done until we know everything works ok.. and then all the changes can be
 * done in one fell swoop when we have claimed all the buffers needed.
 *
 * Anybody can rename anything with this: the permission checks are left to the
 * higher-level routines.
 */
static int do_ext2_rename (struct inode * old_dir, struct dentry *old_dentry,
                           struct inode * new_dir,struct dentry *new_dentry)
{
        struct inode * old_inode, * new_inode;
        struct buffer_head * old_bh, * new_bh, * dir_bh;
        struct ext2_dir_entry_2 * old_de, * new_de;
        int retval;

        old_bh = new_bh = dir_bh = NULL;
        retval = -ENAMETOOLONG;
        if (old_dentry->d_name.len > EXT2_NAME_LEN)
                goto end_rename;

        old_bh = ext2_find_entry (old_dir, old_dentry->d_name.name, old_dentry->d_name.len, &old_de);
        retval = -ENOENT;
        if (!old_bh)
                goto end_rename;
        old_inode = old_dentry->d_inode;

        retval = -EPERM;
        if ((old_dir->i_mode & S_ISVTX) && 
            current->fsuid != old_inode->i_uid &&
            current->fsuid != old_dir->i_uid && !capable(CAP_FOWNER))
                goto end_rename;
        if (IS_APPEND(old_inode) || IS_IMMUTABLE(old_inode))
                goto end_rename;

        new_inode = new_dentry->d_inode;
        new_bh = ext2_find_entry (new_dir, new_dentry->d_name.name,
                                new_dentry->d_name.len, &new_de);
        if (new_bh) {
                if (!new_inode) {
                        brelse (new_bh);
                        new_bh = NULL;
                } else {
                        DQUOT_INIT(new_inode);
                }
        }
        retval = 0;
        if (new_inode == old_inode)
                goto end_rename;
        if (new_inode && S_ISDIR(new_inode->i_mode)) {
                retval = -EISDIR;
                if (!S_ISDIR(old_inode->i_mode))
                        goto end_rename;
                retval = -EINVAL;
                if (is_subdir(new_dentry, old_dentry))
                        goto end_rename;
                /* Prune any children before testing for busy */
                if (new_dentry->d_count > 1)
                        shrink_dcache_parent(new_dentry);
                retval = -ENOTEMPTY;
                if (!empty_dir (new_inode))
                        goto end_rename;
                retval = -EBUSY;
                if (new_dentry->d_count > 1)
                        goto end_rename;
        }
        retval = -EPERM;
        if (new_inode) {
                if ((new_dir->i_mode & S_ISVTX) &&
                    current->fsuid != new_inode->i_uid &&
                    current->fsuid != new_dir->i_uid && !capable(CAP_FOWNER))
                        goto end_rename;
                if (IS_APPEND(new_inode) || IS_IMMUTABLE(new_inode))
                        goto end_rename;
        }
        if (S_ISDIR(old_inode->i_mode)) {
                retval = -ENOTDIR;
                if (new_inode && !S_ISDIR(new_inode->i_mode))
                        goto end_rename;
                retval = -EINVAL;
                if (is_subdir(new_dentry, old_dentry))
                        goto end_rename;
                dir_bh = ext2_bread (old_inode, 0, 0, &retval);
                if (!dir_bh)
                        goto end_rename;
                if (le32_to_cpu(PARENT_INO(dir_bh->b_data)) != old_dir->i_ino)
                        goto end_rename;
                retval = -EMLINK;
                if (!new_inode && new_dir->i_nlink >= EXT2_LINK_MAX)
                        goto end_rename;
        }
        if (!new_bh) {
                new_bh = ext2_add_entry (new_dir, new_dentry->d_name.name,
                                        new_dentry->d_name.len, &new_de,
                                        &retval);
                if (!new_bh)
                        goto end_rename;
        }
        new_dir->i_version = ++event;

        /*
         * ok, that's it
         */
        new_de->inode = le32_to_cpu(old_inode->i_ino);
        if (EXT2_HAS_INCOMPAT_FEATURE(new_dir->i_sb,
                                      EXT2_FEATURE_INCOMPAT_FILETYPE))
                new_de->file_type = old_de->file_type;
        
        ext2_delete_entry (old_de, old_bh);

        old_dir->i_version = ++event;
        if (new_inode) {
                new_inode->i_nlink--;
                new_inode->i_ctime = CURRENT_TIME;
                mark_inode_dirty(new_inode);
        }
        old_dir->i_ctime = old_dir->i_mtime = CURRENT_TIME;
        old_dir->u.ext2_i.i_flags &= ~EXT2_BTREE_FL;
        mark_inode_dirty(old_dir);
        if (dir_bh) {
                PARENT_INO(dir_bh->b_data) = le32_to_cpu(new_dir->i_ino);
                mark_buffer_dirty(dir_bh, 1);
                old_dir->i_nlink--;
                mark_inode_dirty(old_dir);
                if (new_inode) {
                        new_inode->i_nlink--;
                        mark_inode_dirty(new_inode);
                } else {
                        new_dir->i_nlink++;
                        new_dir->u.ext2_i.i_flags &= ~EXT2_BTREE_FL;
                        mark_inode_dirty(new_dir);
                }
        }
        mark_buffer_dirty(old_bh,  1);
        if (IS_SYNC(old_dir)) {
                ll_rw_block (WRITE, 1, &old_bh);
                wait_on_buffer (old_bh);
        }
        mark_buffer_dirty(new_bh, 1);
        if (IS_SYNC(new_dir)) {
                ll_rw_block (WRITE, 1, &new_bh);
                wait_on_buffer (new_bh);
        }

        /* Update the dcache */
        d_move(old_dentry, new_dentry);
        retval = 0;

end_rename:
        brelse (dir_bh);
        brelse (old_bh);
        brelse (new_bh);
        return retval;
}

/*
 * Ok, rename also locks out other renames, as they can change the parent of
 * a directory, and we don't want any races. Other races are checked for by
 * "do_rename()", which restarts if there are inconsistencies.
 *
 * Note that there is no race between different filesystems: it's only within
 * the same device that races occur: many renames can happen at once, as long
 * as they are on different partitions.
 *
 * In the second extended file system, we use a lock flag stored in the memory
 * super-block.  This way, we really lock other renames only if they occur
 * on the same file system
 */
int ext2_rename (struct inode * old_dir, struct dentry *old_dentry,
                 struct inode * new_dir, struct dentry *new_dentry)
{
        int result;

        while (old_dir->i_sb->u.ext2_sb.s_rename_lock)
                sleep_on (&old_dir->i_sb->u.ext2_sb.s_rename_wait);
        old_dir->i_sb->u.ext2_sb.s_rename_lock = 1;
        result = do_ext2_rename (old_dir, old_dentry, new_dir, new_dentry);
        old_dir->i_sb->u.ext2_sb.s_rename_lock = 0;
        wake_up (&old_dir->i_sb->u.ext2_sb.s_rename_wait);
        return result;
}