namei.c

linux 内核源代码

	return add_dirent_to_buf(handle, dentry, inode, de, bh);
}

/*
 *	ext4_add_entry()
 *
 * adds a file entry to the specified directory, using the same
 * semantics as ext4_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 int ext4_add_entry (handle_t *handle, struct dentry *dentry,
	struct inode *inode)
{
	struct inode *dir = dentry->d_parent->d_inode;
	unsigned long offset;
	struct buffer_head * bh;
	struct ext4_dir_entry_2 *de;
	struct super_block * sb;
	int	retval;
	int	dx_fallback=0;
	unsigned blocksize;
	u32 block, blocks;

	sb = dir->i_sb;
	blocksize = sb->s_blocksize;
	if (!dentry->d_name.len)
		return -EINVAL;
	if (is_dx(dir)) {
		retval = ext4_dx_add_entry(handle, dentry, inode);
		if (!retval || (retval != ERR_BAD_DX_DIR))
			return retval;
		EXT4_I(dir)->i_flags &= ~EXT4_INDEX_FL;
		dx_fallback++;
		ext4_mark_inode_dirty(handle, dir);
	}
	blocks = dir->i_size >> sb->s_blocksize_bits;
	for (block = 0, offset = 0; block < blocks; block++) {
		bh = ext4_bread(handle, dir, block, 0, &retval);
		if(!bh)
			return retval;
		retval = add_dirent_to_buf(handle, dentry, inode, NULL, bh);
		if (retval != -ENOSPC)
			return retval;

		if (blocks == 1 && !dx_fallback &&
		    EXT4_HAS_COMPAT_FEATURE(sb, EXT4_FEATURE_COMPAT_DIR_INDEX))
			return make_indexed_dir(handle, dentry, inode, bh);
		brelse(bh);
	}
	bh = ext4_append(handle, dir, &block, &retval);
	if (!bh)
		return retval;
	de = (struct ext4_dir_entry_2 *) bh->b_data;
	de->inode = 0;
	de->rec_len = cpu_to_le16(blocksize);
	return add_dirent_to_buf(handle, dentry, inode, de, bh);
}

/*
 * Returns 0 for success, or a negative error value
 */
static int ext4_dx_add_entry(handle_t *handle, struct dentry *dentry,
			     struct inode *inode)
{
	struct dx_frame frames[2], *frame;
	struct dx_entry *entries, *at;
	struct dx_hash_info hinfo;
	struct buffer_head * bh;
	struct inode *dir = dentry->d_parent->d_inode;
	struct super_block * sb = dir->i_sb;
	struct ext4_dir_entry_2 *de;
	int err;

	frame = dx_probe(dentry, NULL, &hinfo, frames, &err);
	if (!frame)
		return err;
	entries = frame->entries;
	at = frame->at;

	if (!(bh = ext4_bread(handle,dir, dx_get_block(frame->at), 0, &err)))
		goto cleanup;

	BUFFER_TRACE(bh, "get_write_access");
	err = ext4_journal_get_write_access(handle, bh);
	if (err)
		goto journal_error;

	err = add_dirent_to_buf(handle, dentry, inode, NULL, bh);
	if (err != -ENOSPC) {
		bh = NULL;
		goto cleanup;
	}

	/* Block full, should compress but for now just split */
	dxtrace(printk("using %u of %u node entries\n",
		       dx_get_count(entries), dx_get_limit(entries)));
	/* Need to split index? */
	if (dx_get_count(entries) == dx_get_limit(entries)) {
		u32 newblock;
		unsigned icount = dx_get_count(entries);
		int levels = frame - frames;
		struct dx_entry *entries2;
		struct dx_node *node2;
		struct buffer_head *bh2;

		if (levels && (dx_get_count(frames->entries) ==
			       dx_get_limit(frames->entries))) {
			ext4_warning(sb, __FUNCTION__,
				     "Directory index full!");
			err = -ENOSPC;
			goto cleanup;
		}
		bh2 = ext4_append (handle, dir, &newblock, &err);
		if (!(bh2))
			goto cleanup;
		node2 = (struct dx_node *)(bh2->b_data);
		entries2 = node2->entries;
		node2->fake.rec_len = cpu_to_le16(sb->s_blocksize);
		node2->fake.inode = 0;
		BUFFER_TRACE(frame->bh, "get_write_access");
		err = ext4_journal_get_write_access(handle, frame->bh);
		if (err)
			goto journal_error;
		if (levels) {
			unsigned icount1 = icount/2, icount2 = icount - icount1;
			unsigned hash2 = dx_get_hash(entries + icount1);
			dxtrace(printk("Split index %i/%i\n", icount1, icount2));

			BUFFER_TRACE(frame->bh, "get_write_access"); /* index root */
			err = ext4_journal_get_write_access(handle,
							     frames[0].bh);
			if (err)
				goto journal_error;

			memcpy ((char *) entries2, (char *) (entries + icount1),
				icount2 * sizeof(struct dx_entry));
			dx_set_count (entries, icount1);
			dx_set_count (entries2, icount2);
			dx_set_limit (entries2, dx_node_limit(dir));

			/* Which index block gets the new entry? */
			if (at - entries >= icount1) {
				frame->at = at = at - entries - icount1 + entries2;
				frame->entries = entries = entries2;
				swap(frame->bh, bh2);
			}
			dx_insert_block (frames + 0, hash2, newblock);
			dxtrace(dx_show_index ("node", frames[1].entries));
			dxtrace(dx_show_index ("node",
			       ((struct dx_node *) bh2->b_data)->entries));
			err = ext4_journal_dirty_metadata(handle, bh2);
			if (err)
				goto journal_error;
			brelse (bh2);
		} else {
			dxtrace(printk("Creating second level index...\n"));
			memcpy((char *) entries2, (char *) entries,
			       icount * sizeof(struct dx_entry));
			dx_set_limit(entries2, dx_node_limit(dir));

			/* Set up root */
			dx_set_count(entries, 1);
			dx_set_block(entries + 0, newblock);
			((struct dx_root *) frames[0].bh->b_data)->info.indirect_levels = 1;

			/* Add new access path frame */
			frame = frames + 1;
			frame->at = at = at - entries + entries2;
			frame->entries = entries = entries2;
			frame->bh = bh2;
			err = ext4_journal_get_write_access(handle,
							     frame->bh);
			if (err)
				goto journal_error;
		}
		ext4_journal_dirty_metadata(handle, frames[0].bh);
	}
	de = do_split(handle, dir, &bh, frame, &hinfo, &err);
	if (!de)
		goto cleanup;
	err = add_dirent_to_buf(handle, dentry, inode, de, bh);
	bh = NULL;
	goto cleanup;

journal_error:
	ext4_std_error(dir->i_sb, err);
cleanup:
	if (bh)
		brelse(bh);
	dx_release(frames);
	return err;
}

/*
 * ext4_delete_entry deletes a directory entry by merging it with the
 * previous entry
 */
static int ext4_delete_entry (handle_t *handle,
			      struct inode * dir,
			      struct ext4_dir_entry_2 * de_del,
			      struct buffer_head * bh)
{
	struct ext4_dir_entry_2 * de, * pde;
	int i;

	i = 0;
	pde = NULL;
	de = (struct ext4_dir_entry_2 *) bh->b_data;
	while (i < bh->b_size) {
		if (!ext4_check_dir_entry("ext4_delete_entry", dir, de, bh, i))
			return -EIO;
		if (de == de_del)  {
			BUFFER_TRACE(bh, "get_write_access");
			ext4_journal_get_write_access(handle, bh);
			if (pde)
				pde->rec_len =
					cpu_to_le16(le16_to_cpu(pde->rec_len) +
						    le16_to_cpu(de->rec_len));
			else
				de->inode = 0;
			dir->i_version++;
			BUFFER_TRACE(bh, "call ext4_journal_dirty_metadata");
			ext4_journal_dirty_metadata(handle, bh);
			return 0;
		}
		i += le16_to_cpu(de->rec_len);
		pde = de;
		de = (struct ext4_dir_entry_2 *)
			((char *) de + le16_to_cpu(de->rec_len));
	}
	return -ENOENT;
}

/*
 * DIR_NLINK feature is set if 1) nlinks > EXT4_LINK_MAX or 2) nlinks == 2,
 * since this indicates that nlinks count was previously 1.
 */
static void ext4_inc_count(handle_t *handle, struct inode *inode)
{
	inc_nlink(inode);
	if (is_dx(inode) && inode->i_nlink > 1) {
		/* limit is 16-bit i_links_count */
		if (inode->i_nlink >= EXT4_LINK_MAX || inode->i_nlink == 2) {
			inode->i_nlink = 1;
			EXT4_SET_RO_COMPAT_FEATURE(inode->i_sb,
					      EXT4_FEATURE_RO_COMPAT_DIR_NLINK);
		}
	}
}

/*
 * If a directory had nlink == 1, then we should let it be 1. This indicates
 * directory has >EXT4_LINK_MAX subdirs.
 */
static void ext4_dec_count(handle_t *handle, struct inode *inode)
{
	drop_nlink(inode);
	if (S_ISDIR(inode->i_mode) && inode->i_nlink == 0)
		inc_nlink(inode);
}


static int ext4_add_nondir(handle_t *handle,
		struct dentry *dentry, struct inode *inode)
{
	int err = ext4_add_entry(handle, dentry, inode);
	if (!err) {
		ext4_mark_inode_dirty(handle, inode);
		d_instantiate(dentry, inode);
		return 0;
	}
	drop_nlink(inode);
	iput(inode);
	return err;
}

/*
 * 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 ext4_create (struct inode * dir, struct dentry * dentry, int mode,
		struct nameidata *nd)
{
	handle_t *handle;
	struct inode * inode;
	int err, retries = 0;

retry:
	handle = ext4_journal_start(dir, EXT4_DATA_TRANS_BLOCKS(dir->i_sb) +
					EXT4_INDEX_EXTRA_TRANS_BLOCKS + 3 +
					2*EXT4_QUOTA_INIT_BLOCKS(dir->i_sb));
	if (IS_ERR(handle))
		return PTR_ERR(handle);

	if (IS_DIRSYNC(dir))
		handle->h_sync = 1;

	inode = ext4_new_inode (handle, dir, mode);
	err = PTR_ERR(inode);
	if (!IS_ERR(inode)) {
		inode->i_op = &ext4_file_inode_operations;
		inode->i_fop = &ext4_file_operations;
		ext4_set_aops(inode);
		err = ext4_add_nondir(handle, dentry, inode);
	}
	ext4_journal_stop(handle);
	if (err == -ENOSPC && ext4_should_retry_alloc(dir->i_sb, &retries))
		goto retry;
	return err;
}

static int ext4_mknod (struct inode * dir, struct dentry *dentry,
			int mode, dev_t rdev)
{
	handle_t *handle;
	struct inode *inode;
	int err, retries = 0;

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

retry:
	handle = ext4_journal_start(dir, EXT4_DATA_TRANS_BLOCKS(dir->i_sb) +
					EXT4_INDEX_EXTRA_TRANS_BLOCKS + 3 +
					2*EXT4_QUOTA_INIT_BLOCKS(dir->i_sb));
	if (IS_ERR(handle))
		return PTR_ERR(handle);

	if (IS_DIRSYNC(dir))
		handle->h_sync = 1;

	inode = ext4_new_inode (handle, dir, mode);
	err = PTR_ERR(inode);
	if (!IS_ERR(inode)) {
		init_special_inode(inode, inode->i_mode, rdev);
#ifdef CONFIG_EXT4DEV_FS_XATTR
		inode->i_op = &ext4_special_inode_operations;
#endif
		err = ext4_add_nondir(handle, dentry, inode);
	}
	ext4_journal_stop(handle);
	if (err == -ENOSPC && ext4_should_retry_alloc(dir->i_sb, &retries))
		goto retry;
	return err;
}

static int ext4_mkdir(struct inode * dir, struct dentry * dentry, int mode)
{
	handle_t *handle;
	struct inode * inode;
	struct buffer_head * dir_block;
	struct ext4_dir_entry_2 * de;
	int err, retries = 0;

	if (EXT4_DIR_LINK_MAX(dir))
		return -EMLINK;

retry:
	handle = ext4_journal_start(dir, EXT4_DATA_TRANS_BLOCKS(dir->i_sb) +
					EXT4_INDEX_EXTRA_TRANS_BLOCKS + 3 +
					2*EXT4_QUOTA_INIT_BLOCKS(dir->i_sb));
	if (IS_ERR(handle))
		return PTR_ERR(handle);

	if (IS_DIRSYNC(dir))
		handle->h_sync = 1;

	inode = ext4_new_inode (handle, dir, S_IFDIR | mode);
	err = PTR_ERR(inode);
	if (IS_ERR(inode))
		goto out_stop;

	inode->i_op = &ext4_dir_inode_operations;
	inode->i_fop = &ext4_dir_operations;
	inode->i_size = EXT4_I(inode)->i_disksize = inode->i_sb->s_blocksize;
	dir_block = ext4_bread (handle, inode, 0, 1, &err);
	if (!dir_block) {
		ext4_dec_count(handle, inode); /* is this nlink == 0? */
		ext4_mark_inode_dirty(handle, inode);
		iput (inode);
		goto out_stop;
	}
	BUFFER_TRACE(dir_block, "get_write_access");
	ext4_journal_get_write_access(handle, dir_block);
	de = (struct ext4_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(EXT4_DIR_REC_LEN(de->name_len));
	strcpy (de->name, ".");
	ext4_set_de_type(dir->i_sb, de, S_IFDIR);
	de = (struct ext4_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-EXT4_DIR_REC_LEN(1));
	de->name_len = 2;
	strcpy (de->name, "..");
	ext4_set_de_type(dir->i_sb, de, S_IFDIR);
	inode->i_nlink = 2;
	BUFFER_TRACE(dir_block, "call ext4_journal_dirty_metadata");
	ext4_journal_dirty_metadata(handle, dir_block);
	brelse (dir_block);
	ext4_mark_inode_dirty(handle, inode);
	err = ext4_add_entry (handle, dentry, inode);
	if (err) {
		inode->i_nlink = 0;
		ext4_mark_inode_dirty(handle, inode);
		iput (inode);
		goto out_stop;
	}
	ext4_inc_count(handle, dir);
	ext4_update_dx_flag(dir);
	ext4_mark_inode_dirty(handle, dir);
	d_instantiate(dentry, inode);
out_stop:
	ext4_journal_stop(handle);
	if (err == -ENOSPC && ext4_should_retry_alloc(dir->i_sb, &retries))
		goto retry;
	return err;
}

/*
 * 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 ext4_dir_entry_2 * de, * de1;
	struct super_block * sb;
	int err = 0;

	sb = inode->i_sb;
	if (inode->i_size < EXT4_DIR_REC_LEN(1) + EXT4_DIR_REC_LEN(2) ||
	    !(bh = ext4_bread (NULL, inode, 0, 0, &err))) {
		if (err)
			ext4_error(inode->i_sb, __FUNCTION__,
				   "error %d reading directory #%lu offset 0",
				   err, inode->i_ino);
		else
			ext4_warning(inode->i_sb, __FUNCTION__,
				     "bad directory (dir #%lu) - no data block",
				     inode->i_ino);
		return 1;
	}
	de = (struct ext4_dir_entry_2 *) bh->b_data;
	de1 = (struct ext4_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)) {
		ext4_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 ext4_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)) {
			err = 0;
			brelse (bh);
			bh = ext4_bread (NULL, inode,
				offset >> EXT4_BLOCK_SIZE_BITS(sb), 0, &err);
			if (!bh) {
				if (err)