Re: [LTP] [PATCH] Add new testcases for ext4 new features - V3

Andreas Dilger
2009-10-26T22:18:15Z

On 2009-10-26, at 07:26, Subrata Modak wrote:
> We had recently added EXT4 testcases to LTP. As the author of these
> tests mentioned, we saw 2 such failures in subdirectory limit test:
>
> Ext4 subdir limit test
> ext4-subdir-limit 0 TINFO : Num of dirs to create: 65537, Dir
> name
> len: short name Parent dir: mnt_point, Block
> size: 1024
> mke2fs 1.41.9 (22-Aug-2009)
> tune2fs 1.41.9 (22-Aug-2009)
> Setting test filesystem flag
> /dev/VG1_EXT4/LV1_EXT4: The test_fs flag is set (and ext4 is
> available).
> CLEARED.

You don't need to set the test_fs flag for modern ext4.

> /dev/VG1_EXT4/LV1_EXT4: clean, 10/8847360 files, 2297019/141557760
> blocks
> dumpe2fs 1.41.9 (22-Aug-2009)
> ext4-subdir-limit 1 TPASS : ext4 subdir limit test pass
> ext4-subdir-limit 0 TINFO : Num of dirs to create: 65537, Dir
> name
> len: long name Parent dir: mnt_point, Block
> size: 1024
> mkdir: No space left on device
> ext4-subdir-limit 2 TFAIL : failed to create directories - 19524
> ext4-subdir-limit 0 TINFO : Num of dirs to create: 65537, Dir
> name
> len: short name Parent dir: mnt_point/sub,
> Block
> size: 1024
> mke2fs 1.41.9 (22-Aug-2009)
> tune2fs 1.41.9 (22-Aug-2009)
> Setting test filesystem flag
> /dev/VG1_EXT4/LV1_EXT4: The test_fs flag is set (and ext4 is
> available).
> CLEARED.
> /dev/VG1_EXT4/LV1_EXT4: clean, 12/8847360 files, 2297037/141557760
> blocks
> dumpe2fs 1.41.9 (22-Aug-2009)
> ext4-subdir-limit 3 TPASS : ext4 subdir limit test pass
> ext4-subdir-limit 0 TINFO : Num of dirs to create: 65537, Dir
> name
> len: long name Parent dir: mnt_point/sub,
> Block
> size: 1024
> mkdir: No space left on device
> ext4-subdir-limit 4 TFAIL : failed to create directories - 19483
> ext4-subdir-limit 0 TINFO : Num of dirs to create: 65537, Dir
> name
> len: short name Parent dir: mnt_point, Block
> size: 2048
>
> Is this a known issue for EXT4 ?

Creating many long filenames (255 bytes) in a 1kB block filesystem is a
known issue that is not expected to be fixed (at least I'm not aware of
any work being done in this area). A vast majority of filesystems
today are formatted with 4kB blocks (due to disk size) and the
overhead of
managing 1kB block filesystems makes these only marginally used, and it
is also very rare to have applications with such large filenames.

> We also uncovered that the tests gives a decent 50% lines and over 61%
> function coverage for EXT4 code. Please find the individual coverage
> under EXT4 attached.

Interesting to see this.

> Following the various system information on which we ran the test:
> 1) uname -a
> Linux 2.6.31 #1 SMP Tue Oct 20 22:57:16 IST 2009 i686 i686 i386
> GNU/Linux
>
> 2) grep -i ext4 .config
> CONFIG_EXT4_FS=m
> CONFIG_EXT4DEV_COMPAT=y
> CONFIG_EXT4_FS_XATTR=y
> CONFIG_EXT4_FS_POSIX_ACL=y
> CONFIG_EXT4_FS_SECURITY=y
>
> 3) mkfs.ext4 -V
> mke2fs 1.41.9 (22-Aug-2009)
> Using EXT2FS Library version 1.41.9
> e2fsprogs-1.41.9
> e2fsprogs-libs-1.41.9
>
> 4) LTP used:
> Unreleased CVS repository. See the URL below to download:
> http://ltp.sourceforge.net/documentation/how-to/ltp.php#_3.1,
>
> You can also also directly review the attached patch(which added this
> test cases):
> 26_10_2009-(Miao-Xie<miaox@cn.fujitsu.com>)-
> Add_new_testcases_for_ext4_new_features_V3.patch.regenerated,
>
> 5) I used a single 680GB LVM partition to test this.
>
> Kindly let us know your thoughts on this failures.

Cheers, Andreas
--
Andreas Dilger
Sr. Staff Engineer, Lustre Group
Sun Microsystems of Canada, Inc.

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