Message-ID: <CAOQ4uxh6a1qoZZs2SVxxrKfcd5q0vKkpCMDQ-X5eur3Tg07FXg@mail.gmail.com>
Date:	Fri, 29 Jul 2011 22:46:05 +0300
From:	Amir Goldstein <amir73il@...il.com>
To:	Round Robinjp <roundrobinjp@...oo.co.jp>
Cc:	Dilger Andreas <aedilger@...il.com>, "Ted Ts'o" <tytso@....edu>,
	"linux-ext4@...r.kernel.org" <linux-ext4@...r.kernel.org>
Subject: Re: flashing large eMMC partitions with ext4

On Fri, Jul 29, 2011 at 10:05 PM, Round Robinjp
<roundrobinjp@...oo.co.jp> wrote:
>> When I get to it I will try to play this game and let you guys know if
>> it worked.
>
> Thanks in advance. :-)
> Meanwhile, with my limited knowledge about ext4, I am trying your
> method. It seems it is working. But I am not sure about a few
> things. Details below.
>
>> If you know the estimated disk usage of the initial fs, say 1G:
>> 1. mkfs a 1G ext4 fs with no journal, flex_bg=32, resize=4G
>
> I did this: (hope you meant this)
>
> dd if=/dev/zero of=a.img bs=4K count=256K
> mkfs.ext4 -O ^has_journal,flex_bg -G 32 -E resize=4G a.img
>
>> 2. mount it and cp -a /foo/* /mnt/
>
> I did this:
>
> sudo mount -t ext4 -o loop a.img /mnt/
> cp -a /foo/* /mnt/
>
>> 3. use new online resize to resize fs to 4G (maintaining flex_bg layout)
>
> I did this: (hope you meant this)

I meant using a newer version of resize2fs (which you do not have),
but running fsck on the flashed image can be a valid alternative.

>
> e2fsck -f a.img
> resize2fs a.img 4G
>
>> 4. add journal to mounted fs (.journal file should be allocated with goal 0??)
>
> I skipped this because I am not sure how to allocate .journal with goal 0.

So your fs has no journal...
I meant to run:
# tune2fs -O has_journal /dev/loop<N>
while the image is mounted.
I never tried it, but I think it should create a .journal file at the
beginning of the partition.

>
>> if my calculations are correct, the only blocks written beyond the 1G mark
>> are the super block backup copies, so truncating the resulting image to 1G
>> won't do any damage - even fsck shouldn't complain.
>
> I did this:
>
> sudo umount /mnt
> truncate -s 1G a.img
> e2fsck -f a.img
>  # this complains about several illegal blocks

They are "illegal" because they are beyond the end of the device.
You need to truncate -s 4G (after truncate -s 1G) to simulate that you
flashed to image to a 4G partition.

Please try that and send the post truncate/extend fsck report.
Please also send the 'dumpe2fs' of the pre-truncate and
post-truncate/extend image.

>  # but after fixing, a.img mounts okay and files
>  # inside it looks okay.

Yes, those files would look OK, but trying to write new files to the
'phantom' 3G, can cause some problem along the way.

>
>
> Full operation log below:
>
> --------------------------------------
> --------------------------------------
> --------------------------------------
> $ dd if=/dev/zero of=a.img bs=4K count=256K
> 262144+0 records in
> 262144+0 records out
> 1073741824 bytes (1.1 GB) copied, 23.4067 s, 45.9 MB/s
>
> $ mkfs.ext4 -O ^has_journal,flex_bg -G 32 -E resize=4G a.img
> mke2fs 1.41.14 (22-Dec-2010)
> a.img is not a block special device.
> Proceed anyway? (y,n) y
> Filesystem label=
> OS type: Linux
> Block size=4096 (log=2)
> Fragment size=4096 (log=2)
> Stride=0 blocks, Stripe width=0 blocks
> 65536 inodes, 262144 blocks
> 13107 blocks (5.00%) reserved for the super user
> First data block=0
> Maximum filesystem blocks=268435456
> 8 block groups
> 32768 blocks per group, 32768 fragments per group
> 8192 inodes per group
> Superblock backups stored on blocks:
>        32768, 98304, 163840, 229376
>
> Writing inode tables: done
> Writing superblocks and filesystem accounting information: done
>
> This filesystem will be automatically checked every 31 mounts or
> 180 days, whichever comes first.  Use tune2fs -c or -i to override.
>
> $ sudo mount -t ext4 -o loop a.img /mnt/
>
> $ du -sh /usr/src/
> 92M     /usr/src/
>
> $ cp -a /usr/src/* /mnt/
>
> $ e2fsck -f a.img
> e2fsck 1.41.14 (22-Dec-2010)
> Pass 1: Checking inodes, blocks, and sizes
> Pass 2: Checking directory structure
> Pass 3: Checking directory connectivity
> Pass 4: Checking reference counts
> Pass 5: Checking group summary information
> a.img: 11/65536 files (0.0% non-contiguous), 4443/262144 blocks
>
> $ resize2fs a.img 4G
> resize2fs 1.41.14 (22-Dec-2010)
> Resizing the filesystem on a.img to 1048576 (4k) blocks.
> The filesystem on a.img is now 1048576 blocks long.
>
> $ sudo umount /mnt
>
> $ truncate -s 1G a.img
>
> $ e2fsck -f a.img
> e2fsck 1.41.14 (22-Dec-2010)
> Pass 1: Checking inodes, blocks, and sizes
> Inode 7 has illegal block(s).  Clear<y>? yes
>
> Illegal block #2064 (294914) in inode 7.  CLEARED.
> Illegal block #2065 (819202) in inode 7.  CLEARED.
> Illegal block #2066 (884738) in inode 7.  CLEARED.
> Illegal block #3088 (294915) in inode 7.  CLEARED.
> Illegal block #3089 (819203) in inode 7.  CLEARED.
> Illegal block #3090 (884739) in inode 7.  CLEARED.
> Illegal block #4112 (294916) in inode 7.  CLEARED.
> Illegal block #4113 (819204) in inode 7.  CLEARED.
> Illegal block #4114 (884740) in inode 7.  CLEARED.
> Illegal block #5136 (294917) in inode 7.  CLEARED.
> Illegal block #5137 (819205) in inode 7.  CLEARED.
> Too many illegal blocks in inode 7.
> Clear inode<y>? yes
>
> Restarting e2fsck from the beginning...
> Resize inode not valid.  Recreate<y>? yes

So fsck re-created the resize inode, which it had just cleared...
I bet if you run fsck again you would get the exact same errors over again.

>
> Pass 1: Checking inodes, blocks, and sizes
> Pass 2: Checking directory structure
> Pass 3: Checking directory connectivity
> Pass 4: Checking reference counts
> Pass 5: Checking group summary information
> Free blocks count wrong for group #0 (24746, counted=24747).
> Fix<y>? yes
>
> Free blocks count wrong (234383, counted=234384).
> Fix<y>? yes
>
>
> a.img: ***** FILE SYSTEM WAS MODIFIED *****
> a.img: 20864/65536 files (0.0% non-contiguous), 27760/262144 blocks
>
> $ tune2fs -l a.img
> tune2fs 1.41.14 (22-Dec-2010)
> Filesystem volume name:   <none>
> Last mounted on:          /mnt
> Filesystem UUID:          56f4818f-ee66-4a30-a31c-917b0816f139
> Filesystem magic number:  0xEF53
> Filesystem revision #:    1 (dynamic)
> Filesystem features:      ext_attr resize_inode dir_index filetype extent flex_bg sparse_super large_file huge_file uninit_bg dir_nlink extra_isize
> Filesystem flags:         signed_directory_hash
> Default mount options:    (none)
> Filesystem state:         clean
> Errors behavior:          Continue
> Filesystem OS type:       Linux
> Inode count:              65536
> Block count:              262144
> Reserved block count:     13107
> Free blocks:              234384
> Free inodes:              44672
> First block:              0
> Block size:               4096
> Fragment size:            4096
> Reserved GDT blocks:      63
> Blocks per group:         32768
> Fragments per group:      32768
> Inodes per group:         8192
> Inode blocks per group:   512
> Flex block group size:    32
> Filesystem created:       Sat Jul 30 03:18:44 2011
> Last mount time:          Sat Jul 30 03:19:04 2011
> Last write time:          Sat Jul 30 03:28:39 2011
> Mount count:              0
> Maximum mount count:      31
> Last checked:             Sat Jul 30 03:28:39 2011
> Check interval:           15552000 (6 months)
> Next check after:         Thu Jan 26 03:28:39 2012
> Lifetime writes:          722 kB
> Reserved blocks uid:      0 (user root)
> Reserved blocks gid:      0 (group root)
> First inode:              11
> Inode size:               256
> Required extra isize:     28
> Desired extra isize:      28
> Default directory hash:   half_md4
> Directory Hash Seed:      6d50d9cc-e370-4868-acaa-92f7414df164
>
> $ sudo mount -t ext4 -o loop a.img /mnt/
>
> $ sudo du -sh /mnt/
> 92M     /mnt/
>
> $ cat /mnt/linux-headers-2.6.38-8/Documentation/Makefile
> obj-m := DocBook/ accounting/ auxdisplay/ connector/ \
>        filesystems/ filesystems/configfs/ ia64/ laptops/ networking/ \
>        pcmcia/ spi/ timers/ vm/ watchdog/src/
>
> $ ls -la /mnt/
> total 32
> drwxr-xr-x  5 round round  4096 Jul 30 03:26 .
> drwxr-xr-x 23 root root  4096 Jul  9 01:24 ..
> drwxr-xr-x 24 round round  4096 Apr 26 08:08 linux-headers-2.6.38-8
> drwxr-xr-x  7 round round  4096 Apr 26 08:08 linux-headers-2.6.38-8-generic
> drwx------  2 root root 16384 Jul 30 03:18 lost+found
>
> $ sudo umount /mnt
> -------------------------------------
> -------------------------------------
> -------------------------------------
>
--
To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Powered by blists - more mailing lists