linux-ext4 - Re: Problems with the max value for create directory

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Date:	Tue, 23 Dec 2008 13:02:25 +0900
From:	Toshiyuki Okajima <toshi.okajima@...fujitsu.com>
To:	Zhang Xiliang <zhangxiliang@...fujitsu.com>
CC:	linux-ext4@...r.kernel.org
Subject: Re: Problems with the max value for create directory

Hi,

Zhang Xiliang wrote:
> Hi,
> 
> I creat 65537 long directories and failed when the block size is 1024.
> 
> # mkfs.ext4dev -b 1024 -I 256 /dev/hda3
> # tune2fs -E test_fs -O extents /dev/hda3
> # mount -t ext4dev /dev/hda3 /mnt
> # ./create_long_dirs 65537 /mnt
> 
> The code of create_long_dirs.c:

ext4 filesystem cannot make over 65000 links toward a file.
(ext3 filesystem cannot make over 32000 links toward a file.)
This test makes over 65000 links toward /mnt-directory.
(Creating 65000 sub-directories makes 65000 links toward /mnt-directory.)

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;

This limit is ext4's specification.

Regards,
Toshiyuki Okajima

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