<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-stable.git/fs/jbd2, branch v3.3.6</title>
<subtitle>Linux kernel stable tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/'/>
<entry>
<title>jbd2: use GFP_NOFS for blkdev_issue_flush</title>
<updated>2012-04-27T17:16:49+00:00</updated>
<author>
<name>Shaohua Li</name>
<email>shli@kernel.org</email>
</author>
<published>2012-04-13T02:27:35+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=633a19a518ac8a58f02ece56e482a577831b70e2'/>
<id>633a19a518ac8a58f02ece56e482a577831b70e2</id>
<content type='text'>
commit 99aa78466777083255b876293e9e83dec7cd809a upstream.

flush request is issued in transaction commit code path, so looks using
GFP_KERNEL to allocate memory for flush request bio falls into the classic
deadlock issue.  I saw btrfs and dm get it right, but ext4, xfs and md are
using GFP.

Signed-off-by: Shaohua Li &lt;shli@fusionio.com&gt;
Signed-off-by: Theodore Ts'o &lt;tytso@mit.edu&gt;
Reviewed-by: Jan Kara &lt;jack@suse.cz&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 99aa78466777083255b876293e9e83dec7cd809a upstream.

flush request is issued in transaction commit code path, so looks using
GFP_KERNEL to allocate memory for flush request bio falls into the classic
deadlock issue.  I saw btrfs and dm get it right, but ext4, xfs and md are
using GFP.

Signed-off-by: Shaohua Li &lt;shli@fusionio.com&gt;
Signed-off-by: Theodore Ts'o &lt;tytso@mit.edu&gt;
Reviewed-by: Jan Kara &lt;jack@suse.cz&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>jbd2: clear BH_Delay &amp; BH_Unwritten in journal_unmap_buffer</title>
<updated>2012-04-02T17:32:11+00:00</updated>
<author>
<name>Eric Sandeen</name>
<email>sandeen@redhat.com</email>
</author>
<published>2012-02-20T22:53:01+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=7da65e2c13ad21640c9003f78104fadfed6302b8'/>
<id>7da65e2c13ad21640c9003f78104fadfed6302b8</id>
<content type='text'>
commit 15291164b22a357cb211b618adfef4fa82fc0de3 upstream.

journal_unmap_buffer()'s zap_buffer: code clears a lot of buffer head
state ala discard_buffer(), but does not touch _Delay or _Unwritten as
discard_buffer() does.

This can be problematic in some areas of the ext4 code which assume
that if they have found a buffer marked unwritten or delay, then it's
a live one.  Perhaps those spots should check whether it is mapped
as well, but if jbd2 is going to tear down a buffer, let's really
tear it down completely.

Without this I get some fsx failures on sub-page-block filesystems
up until v3.2, at which point 4e96b2dbbf1d7e81f22047a50f862555a6cb87cb
and 189e868fa8fdca702eb9db9d8afc46b5cb9144c9 make the failures go
away, because buried within that large change is some more flag
clearing.  I still think it's worth doing in jbd2, since
-&gt;invalidatepage leads here directly, and it's the right place
to clear away these flags.

Signed-off-by: Eric Sandeen &lt;sandeen@redhat.com&gt;
Signed-off-by: "Theodore Ts'o" &lt;tytso@mit.edu&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 15291164b22a357cb211b618adfef4fa82fc0de3 upstream.

journal_unmap_buffer()'s zap_buffer: code clears a lot of buffer head
state ala discard_buffer(), but does not touch _Delay or _Unwritten as
discard_buffer() does.

This can be problematic in some areas of the ext4 code which assume
that if they have found a buffer marked unwritten or delay, then it's
a live one.  Perhaps those spots should check whether it is mapped
as well, but if jbd2 is going to tear down a buffer, let's really
tear it down completely.

Without this I get some fsx failures on sub-page-block filesystems
up until v3.2, at which point 4e96b2dbbf1d7e81f22047a50f862555a6cb87cb
and 189e868fa8fdca702eb9db9d8afc46b5cb9144c9 make the failures go
away, because buried within that large change is some more flag
clearing.  I still think it's worth doing in jbd2, since
-&gt;invalidatepage leads here directly, and it's the right place
to clear away these flags.

Signed-off-by: Eric Sandeen &lt;sandeen@redhat.com&gt;
Signed-off-by: "Theodore Ts'o" &lt;tytso@mit.edu&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>Merge branch 'for_linus' into for_linus_merged</title>
<updated>2012-01-10T16:54:07+00:00</updated>
<author>
<name>Theodore Ts'o</name>
<email>tytso@mit.edu</email>
</author>
<published>2012-01-10T16:54:07+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=ff9cb1c4eead5e4c292e75cd3170a82d66944101'/>
<id>ff9cb1c4eead5e4c292e75cd3170a82d66944101</id>
<content type='text'>
Conflicts:
	fs/ext4/ioctl.c
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Conflicts:
	fs/ext4/ioctl.c
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial</title>
<updated>2012-01-08T21:21:22+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2012-01-08T21:21:22+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=98793265b429a3f0b3f1750e74d67cd4d740d162'/>
<id>98793265b429a3f0b3f1750e74d67cd4d740d162</id>
<content type='text'>
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial: (53 commits)
  Kconfig: acpi: Fix typo in comment.
  misc latin1 to utf8 conversions
  devres: Fix a typo in devm_kfree comment
  btrfs: free-space-cache.c: remove extra semicolon.
  fat: Spelling s/obsolate/obsolete/g
  SCSI, pmcraid: Fix spelling error in a pmcraid_err() call
  tools/power turbostat: update fields in manpage
  mac80211: drop spelling fix
  types.h: fix comment spelling for 'architectures'
  typo fixes: aera -&gt; area, exntension -&gt; extension
  devices.txt: Fix typo of 'VMware'.
  sis900: Fix enum typo 'sis900_rx_bufer_status'
  decompress_bunzip2: remove invalid vi modeline
  treewide: Fix comment and string typo 'bufer'
  hyper-v: Update MAINTAINERS
  treewide: Fix typos in various parts of the kernel, and fix some comments.
  clockevents: drop unknown Kconfig symbol GENERIC_CLOCKEVENTS_MIGR
  gpio: Kconfig: drop unknown symbol 'CS5535_GPIO'
  leds: Kconfig: Fix typo 'D2NET_V2'
  sound: Kconfig: drop unknown symbol ARCH_CLPS7500
  ...

Fix up trivial conflicts in arch/powerpc/platforms/40x/Kconfig (some new
kconfig additions, close to removed commented-out old ones)
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial: (53 commits)
  Kconfig: acpi: Fix typo in comment.
  misc latin1 to utf8 conversions
  devres: Fix a typo in devm_kfree comment
  btrfs: free-space-cache.c: remove extra semicolon.
  fat: Spelling s/obsolate/obsolete/g
  SCSI, pmcraid: Fix spelling error in a pmcraid_err() call
  tools/power turbostat: update fields in manpage
  mac80211: drop spelling fix
  types.h: fix comment spelling for 'architectures'
  typo fixes: aera -&gt; area, exntension -&gt; extension
  devices.txt: Fix typo of 'VMware'.
  sis900: Fix enum typo 'sis900_rx_bufer_status'
  decompress_bunzip2: remove invalid vi modeline
  treewide: Fix comment and string typo 'bufer'
  hyper-v: Update MAINTAINERS
  treewide: Fix typos in various parts of the kernel, and fix some comments.
  clockevents: drop unknown Kconfig symbol GENERIC_CLOCKEVENTS_MIGR
  gpio: Kconfig: drop unknown symbol 'CS5535_GPIO'
  leds: Kconfig: Fix typo 'D2NET_V2'
  sound: Kconfig: drop unknown symbol ARCH_CLPS7500
  ...

Fix up trivial conflicts in arch/powerpc/platforms/40x/Kconfig (some new
kconfig additions, close to removed commented-out old ones)
</pre>
</div>
</content>
</entry>
<entry>
<title>jbd2: fix hung processes in jbd2_journal_lock_updates()</title>
<updated>2012-01-05T03:03:11+00:00</updated>
<author>
<name>Jan Kara</name>
<email>jack@suse.cz</email>
</author>
<published>2012-01-05T03:03:11+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=9837d8e982b7e87a7207f90618e45d460e196e6a'/>
<id>9837d8e982b7e87a7207f90618e45d460e196e6a</id>
<content type='text'>
Toshiyuki Okajima found out that when running

for ((i=0; i &lt; 100000; i++)); do
        if ((i%2 == 0)); then
                chattr +j /mnt/file
        else
                chattr -j /mnt/file
        fi
        echo "0" &gt;&gt; /mnt/file
done

process sometimes hangs indefinitely in jbd2_journal_lock_updates().

Toshiyuki identified that the following race happens:

jbd2_journal_lock_updates()            |jbd2_journal_stop()
---------------------------------------+---------------------------------------
 write_lock(&amp;journal-&gt;j_state_lock)    |    .
 ++journal-&gt;j_barrier_count            |    .
 spin_lock(&amp;tran-&gt;t_handle_lock)       |    .
 atomic_read(&amp;tran-&gt;t_updates) //not 0 |
                                       | atomic_dec_and_test(&amp;tran-&gt;t_updates)
                                       |    // t_updates = 0
                                       | wake_up(&amp;journal-&gt;j_wait_updates)
 prepare_to_wait()                     |    // no process is woken up.
 spin_unlock(&amp;tran-&gt;t_handle_lock)     |
 write_unlock(&amp;journal-&gt;j_state_lock)  |
 schedule() // never return            |

We fix the problem by first calling prepare_to_wait() and only after that
checking t_updates in jbd2_journal_lock_updates().

Reported-and-analyzed-by: Toshiyuki Okajima &lt;toshi.okajima@jp.fujitsu.com&gt;
Signed-off-by: Jan Kara &lt;jack@suse.cz&gt;
Signed-off-by: "Theodore Ts'o" &lt;tytso@mit.edu&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Toshiyuki Okajima found out that when running

for ((i=0; i &lt; 100000; i++)); do
        if ((i%2 == 0)); then
                chattr +j /mnt/file
        else
                chattr -j /mnt/file
        fi
        echo "0" &gt;&gt; /mnt/file
done

process sometimes hangs indefinitely in jbd2_journal_lock_updates().

Toshiyuki identified that the following race happens:

jbd2_journal_lock_updates()            |jbd2_journal_stop()
---------------------------------------+---------------------------------------
 write_lock(&amp;journal-&gt;j_state_lock)    |    .
 ++journal-&gt;j_barrier_count            |    .
 spin_lock(&amp;tran-&gt;t_handle_lock)       |    .
 atomic_read(&amp;tran-&gt;t_updates) //not 0 |
                                       | atomic_dec_and_test(&amp;tran-&gt;t_updates)
                                       |    // t_updates = 0
                                       | wake_up(&amp;journal-&gt;j_wait_updates)
 prepare_to_wait()                     |    // no process is woken up.
 spin_unlock(&amp;tran-&gt;t_handle_lock)     |
 write_unlock(&amp;journal-&gt;j_state_lock)  |
 schedule() // never return            |

We fix the problem by first calling prepare_to_wait() and only after that
checking t_updates in jbd2_journal_lock_updates().

Reported-and-analyzed-by: Toshiyuki Okajima &lt;toshi.okajima@jp.fujitsu.com&gt;
Signed-off-by: Jan Kara &lt;jack@suse.cz&gt;
Signed-off-by: "Theodore Ts'o" &lt;tytso@mit.edu&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>jbd2: clear revoked flag on buffers before a new transaction started</title>
<updated>2011-12-28T22:46:46+00:00</updated>
<author>
<name>Yongqiang Yang</name>
<email>xiaoqiangnk@gmail.com</email>
</author>
<published>2011-12-28T22:46:46+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=1ba37268cd19e5a2a80924bfe8618bf1ba3e8249'/>
<id>1ba37268cd19e5a2a80924bfe8618bf1ba3e8249</id>
<content type='text'>
Currently, we clear revoked flag only when a block is reused.  However,
this can tigger a false journal error.  Consider a situation when a block
is used as a meta block and is deleted(revoked) in ordered mode, then the
block is allocated as a data block to a file.  At this moment, user changes
the file's journal mode from ordered to journaled and truncates the file.
The block will be considered re-revoked by journal because it has revoked
flag still pending from the last transaction and an assertion triggers.

We fix the problem by keeping the revoked status more uptodate - we clear
revoked flag when switching revoke tables to reflect there is no revoked
buffers in current transaction any more.

Signed-off-by: Yongqiang Yang &lt;xiaoqiangnk@gmail.com&gt;
Signed-off-by: "Theodore Ts'o" &lt;tytso@mit.edu&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Currently, we clear revoked flag only when a block is reused.  However,
this can tigger a false journal error.  Consider a situation when a block
is used as a meta block and is deleted(revoked) in ordered mode, then the
block is allocated as a data block to a file.  At this moment, user changes
the file's journal mode from ordered to journaled and truncates the file.
The block will be considered re-revoked by journal because it has revoked
flag still pending from the last transaction and an assertion triggers.

We fix the problem by keeping the revoked status more uptodate - we clear
revoked flag when switching revoke tables to reflect there is no revoked
buffers in current transaction any more.

Signed-off-by: Yongqiang Yang &lt;xiaoqiangnk@gmail.com&gt;
Signed-off-by: "Theodore Ts'o" &lt;tytso@mit.edu&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>treewide: Fix comment and string typo 'bufer'</title>
<updated>2011-12-06T08:53:40+00:00</updated>
<author>
<name>Paul Bolle</name>
<email>pebolle@tiscali.nl</email>
</author>
<published>2011-12-05T12:00:34+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=90802ed9c3dbab2e067bd9fc67a30e66e6774e8f'/>
<id>90802ed9c3dbab2e067bd9fc67a30e66e6774e8f</id>
<content type='text'>
Signed-off-by: Paul Bolle &lt;pebolle@tiscali.nl&gt;
Signed-off-by: Jiri Kosina &lt;jkosina@suse.cz&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Signed-off-by: Paul Bolle &lt;pebolle@tiscali.nl&gt;
Signed-off-by: Jiri Kosina &lt;jkosina@suse.cz&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>freezer: unexport refrigerator() and update try_to_freeze() slightly</title>
<updated>2011-11-21T20:32:22+00:00</updated>
<author>
<name>Tejun Heo</name>
<email>tj@kernel.org</email>
</author>
<published>2011-11-21T20:32:22+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=a0acae0e886d44bd5ce6d2f173c1ace0fcf0d9f6'/>
<id>a0acae0e886d44bd5ce6d2f173c1ace0fcf0d9f6</id>
<content type='text'>
There is no reason to export two functions for entering the
refrigerator.  Calling refrigerator() instead of try_to_freeze()
doesn't save anything noticeable or removes any race condition.

* Rename refrigerator() to __refrigerator() and make it return bool
  indicating whether it scheduled out for freezing.

* Update try_to_freeze() to return bool and relay the return value of
  __refrigerator() if freezing().

* Convert all refrigerator() users to try_to_freeze().

* Update documentation accordingly.

* While at it, add might_sleep() to try_to_freeze().

Signed-off-by: Tejun Heo &lt;tj@kernel.org&gt;
Cc: Samuel Ortiz &lt;samuel@sortiz.org&gt;
Cc: Chris Mason &lt;chris.mason@oracle.com&gt;
Cc: "Theodore Ts'o" &lt;tytso@mit.edu&gt;
Cc: Steven Whitehouse &lt;swhiteho@redhat.com&gt;
Cc: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Cc: Jan Kara &lt;jack@suse.cz&gt;
Cc: KONISHI Ryusuke &lt;konishi.ryusuke@lab.ntt.co.jp&gt;
Cc: Christoph Hellwig &lt;hch@infradead.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
There is no reason to export two functions for entering the
refrigerator.  Calling refrigerator() instead of try_to_freeze()
doesn't save anything noticeable or removes any race condition.

* Rename refrigerator() to __refrigerator() and make it return bool
  indicating whether it scheduled out for freezing.

* Update try_to_freeze() to return bool and relay the return value of
  __refrigerator() if freezing().

* Convert all refrigerator() users to try_to_freeze().

* Update documentation accordingly.

* While at it, add might_sleep() to try_to_freeze().

Signed-off-by: Tejun Heo &lt;tj@kernel.org&gt;
Cc: Samuel Ortiz &lt;samuel@sortiz.org&gt;
Cc: Chris Mason &lt;chris.mason@oracle.com&gt;
Cc: "Theodore Ts'o" &lt;tytso@mit.edu&gt;
Cc: Steven Whitehouse &lt;swhiteho@redhat.com&gt;
Cc: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Cc: Jan Kara &lt;jack@suse.cz&gt;
Cc: KONISHI Ryusuke &lt;konishi.ryusuke@lab.ntt.co.jp&gt;
Cc: Christoph Hellwig &lt;hch@infradead.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>jbd2: Unify log messages in jbd2 code</title>
<updated>2011-11-01T23:09:18+00:00</updated>
<author>
<name>Eryu Guan</name>
<email>guaneryu@gmail.com</email>
</author>
<published>2011-11-01T23:09:18+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=f2a44523b20f323e4aef7c16261d34d6f0a4bf06'/>
<id>f2a44523b20f323e4aef7c16261d34d6f0a4bf06</id>
<content type='text'>
Some jbd2 code prints out kernel messages with "JBD2: " prefix, at the
same time other jbd2 code prints with "JBD: " prefix. Unify the prefix
to "JBD2: ".

Signed-off-by: Eryu Guan &lt;guaneryu@gmail.com&gt;
Signed-off-by: "Theodore Ts'o" &lt;tytso@mit.edu&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Some jbd2 code prints out kernel messages with "JBD2: " prefix, at the
same time other jbd2 code prints with "JBD: " prefix. Unify the prefix
to "JBD2: ".

Signed-off-by: Eryu Guan &lt;guaneryu@gmail.com&gt;
Signed-off-by: "Theodore Ts'o" &lt;tytso@mit.edu&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>jbd/jbd2: validate sb-&gt;s_first in journal_get_superblock()</title>
<updated>2011-11-01T23:04:59+00:00</updated>
<author>
<name>Eryu Guan</name>
<email>guaneryu@gmail.com</email>
</author>
<published>2011-11-01T23:04:59+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=8762202dd0d6e46854f786bdb6fb3780a1625efe'/>
<id>8762202dd0d6e46854f786bdb6fb3780a1625efe</id>
<content type='text'>
I hit a J_ASSERT(blocknr != 0) failure in cleanup_journal_tail() when
mounting a fsfuzzed ext3 image. It turns out that the corrupted ext3
image has s_first = 0 in journal superblock, and the 0 is passed to
journal-&gt;j_head in journal_reset(), then to blocknr in
cleanup_journal_tail(), in the end the J_ASSERT failed.

So validate s_first after reading journal superblock from disk in
journal_get_superblock() to ensure s_first is valid.

The following script could reproduce it:

fstype=ext3
blocksize=1024
img=$fstype.img
offset=0
found=0
magic="c0 3b 39 98"

dd if=/dev/zero of=$img bs=1M count=8
mkfs -t $fstype -b $blocksize -F $img
filesize=`stat -c %s $img`
while [ $offset -lt $filesize ]
do
        if od -j $offset -N 4 -t x1 $img | grep -i "$magic";then
                echo "Found journal: $offset"
                found=1
                break
        fi
        offset=`echo "$offset+$blocksize" | bc`
done

if [ $found -ne 1 ];then
        echo "Magic \"$magic\" not found"
        exit 1
fi

dd if=/dev/zero of=$img seek=$(($offset+23)) conv=notrunc bs=1 count=1

mkdir -p ./mnt
mount -o loop $img ./mnt

Cc: Jan Kara &lt;jack@suse.cz&gt;
Signed-off-by: Eryu Guan &lt;guaneryu@gmail.com&gt;
Signed-off-by: "Theodore Ts'o" &lt;tytso@mit.edu&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
I hit a J_ASSERT(blocknr != 0) failure in cleanup_journal_tail() when
mounting a fsfuzzed ext3 image. It turns out that the corrupted ext3
image has s_first = 0 in journal superblock, and the 0 is passed to
journal-&gt;j_head in journal_reset(), then to blocknr in
cleanup_journal_tail(), in the end the J_ASSERT failed.

So validate s_first after reading journal superblock from disk in
journal_get_superblock() to ensure s_first is valid.

The following script could reproduce it:

fstype=ext3
blocksize=1024
img=$fstype.img
offset=0
found=0
magic="c0 3b 39 98"

dd if=/dev/zero of=$img bs=1M count=8
mkfs -t $fstype -b $blocksize -F $img
filesize=`stat -c %s $img`
while [ $offset -lt $filesize ]
do
        if od -j $offset -N 4 -t x1 $img | grep -i "$magic";then
                echo "Found journal: $offset"
                found=1
                break
        fi
        offset=`echo "$offset+$blocksize" | bc`
done

if [ $found -ne 1 ];then
        echo "Magic \"$magic\" not found"
        exit 1
fi

dd if=/dev/zero of=$img seek=$(($offset+23)) conv=notrunc bs=1 count=1

mkdir -p ./mnt
mount -o loop $img ./mnt

Cc: Jan Kara &lt;jack@suse.cz&gt;
Signed-off-by: Eryu Guan &lt;guaneryu@gmail.com&gt;
Signed-off-by: "Theodore Ts'o" &lt;tytso@mit.edu&gt;
</pre>
</div>
</content>
</entry>
</feed>
