linux-stable.git/fs/ext4, branch v3.2.16

ext4: address scalability issue by removing extent cache statistics

2012-04-22T22:30:59+00:00

commit 9cd70b347e9761ea2d2ac3d758c529a48a8193e6 upstream.

Andi Kleen and Tim Chen have reported that under certain circumstances
the extent cache statistics are causing scalability problems due to
cache line bounces.

Signed-off-by: "Theodore Ts'o" 
Signed-off-by: Greg Kroah-Hartman

ext4: check for zero length extent

2012-04-02T16:53:04+00:00

commit 31d4f3a2f3c73f279ff96a7135d7202ef6833f12 upstream.

Explicitly test for an extent whose length is zero, and flag that as a
corrupted extent.

This avoids a kernel BUG_ON assertion failure.

Tested: Without this patch, the file system image found in
tests/f_ext_zero_len/image.gz in the latest e2fsprogs sources causes a
kernel panic.  With this patch, an ext4 file system error is noted
instead, and the file system is marked as being corrupted.

https://bugzilla.kernel.org/show_bug.cgi?id=42859

Signed-off-by: "Theodore Ts'o" 
Signed-off-by: Greg Kroah-Hartman

ext4: fix race between sync and completed io work

2012-04-02T16:53:03+00:00

commit 491caa43639abcffaa645fbab372a7ef4ce2975c upstream.

The following command line will leave the aio-stress process unkillable
on an ext4 file system (in my case, mounted on /mnt/test):

aio-stress -t 20 -s 10 -O -S -o 2 -I 1000 /mnt/test/aiostress.3561.4 /mnt/test/aiostress.3561.4.20 /mnt/test/aiostress.3561.4.19 /mnt/test/aiostress.3561.4.18 /mnt/test/aiostress.3561.4.17 /mnt/test/aiostress.3561.4.16 /mnt/test/aiostress.3561.4.15 /mnt/test/aiostress.3561.4.14 /mnt/test/aiostress.3561.4.13 /mnt/test/aiostress.3561.4.12 /mnt/test/aiostress.3561.4.11 /mnt/test/aiostress.3561.4.10 /mnt/test/aiostress.3561.4.9 /mnt/test/aiostress.3561.4.8 /mnt/test/aiostress.3561.4.7 /mnt/test/aiostress.3561.4.6 /mnt/test/aiostress.3561.4.5 /mnt/test/aiostress.3561.4.4 /mnt/test/aiostress.3561.4.3 /mnt/test/aiostress.3561.4.2

This is using the aio-stress program from the xfstests test suite.
That particular command line tells aio-stress to do random writes to
20 files from 20 threads (one thread per file). The files are NOT
preallocated, so you will get writes to random offsets within the
file, thus creating holes and extending i_size. It also opens the
file with O_DIRECT and O_SYNC.

On to the problem. When an I/O requires unwritten extent conversion,
it is queued onto the completed_io_list for the ext4 inode. Two code
paths will pull work items from this list. The first is the
ext4_end_io_work routine, and the second is ext4_flush_completed_IO,
which is called via the fsync path (and O_SYNC handling, as well).
There are two issues I've found in these code paths. First, if the
fsync path beats the work routine to a particular I/O, the work
routine will free the io_end structure! It does not take into account
the fact that the io_end may still be in use by the fsync path. I've
fixed this issue by adding yet another IO_END flag, indicating that
the io_end is being processed by the fsync path.

The second problem is that the work routine will make an assignment to
io->flag outside of the lock. I have witnessed this result in a hang
at umount. Moving the flag setting inside the lock resolved that
problem.

The problem was introduced by commit b82e384c7b ("ext4: optimize
locking for end_io extent conversion"), which first appeared in 3.2.
As such, the fix should be backported to that release (probably along
with the unwritten extent conversion race fix).

Signed-off-by: Jeff Moyer
Signed-off-by: "Theodore Ts'o"
Signed-off-by: Greg Kroah-Hartman

ext4: fix race between unwritten extent conversion and truncate

2012-04-02T16:53:03+00:00

commit 266991b13890049ee1a6bb95b9817f06339ee3d7 upstream.

The following comment in ext4_end_io_dio caught my attention:

	/* XXX: probably should move into the real I/O completion handler */
        inode_dio_done(inode);

The truncate code takes i_mutex, then calls inode_dio_wait.  Because the
ext4 code path above will end up dropping the mutex before it is
reacquired by the worker thread that does the extent conversion, it
seems to me that the truncate can happen out of order.  Jan Kara
mentioned that this might result in error messages in the system logs,
but that should be the extent of the "damage."

The fix is pretty straight-forward: don't call inode_dio_done until the
extent conversion is complete.

Reviewed-by: Jan Kara 
Signed-off-by: Jeff Moyer 
Signed-off-by: "Theodore Ts'o" 
Signed-off-by: Greg Kroah-Hartman

ext4: ignore EXT4_INODE_JOURNAL_DATA flag with delalloc

2012-04-02T16:53:03+00:00

commit 3d2b158262826e8b75bbbfb7b97010838dd92ac7 upstream.

Ext4 does not support data journalling with delayed allocation enabled.
We even do not allow to mount the file system with delayed allocation
and data journalling enabled, however it can be set via FS_IOC_SETFLAGS
so we can hit the inode with EXT4_INODE_JOURNAL_DATA set even on file
system mounted with delayed allocation (default) and that's where
problem arises. The easies way to reproduce this problem is with the
following set of commands:

 mkfs.ext4 /dev/sdd
 mount /dev/sdd /mnt/test1
 dd if=/dev/zero of=/mnt/test1/file bs=1M count=4
 chattr +j /mnt/test1/file
 dd if=/dev/zero of=/mnt/test1/file bs=1M count=4 conv=notrunc
 chattr -j /mnt/test1/file

Additionally it can be reproduced quite reliably with xfstests 272 and
269. In fact the above reproducer is a part of test 272.

To fix this we should ignore the EXT4_INODE_JOURNAL_DATA inode flag if
the file system is mounted with delayed allocation. This can be easily
done by fixing ext4_should_*_data() functions do ignore data journal
flag when delalloc is set (suggested by Ted). We also have to set the
appropriate address space operations for the inode (again, ignoring data
journal flag if delalloc enabled).

Additionally this commit introduces ext4_inode_journal_mode() function
because ext4_should_*_data() has already had a lot of common code and
this change is putting it all into one function so it is easier to
read.

Successfully tested with xfstests in following configurations:

delalloc + data=ordered
delalloc + data=writeback
data=journal
nodelalloc + data=ordered
nodelalloc + data=writeback
nodelalloc + data=journal

Signed-off-by: Lukas Czerner 
Signed-off-by: "Theodore Ts'o" 
Signed-off-by: Greg Kroah-Hartman

ext4: fix undefined behavior in ext4_fill_flex_info()

2012-01-26T00:13:07+00:00

commit d50f2ab6f050311dbf7b8f5501b25f0bf64a439b upstream.

Commit 503358ae01b70ce6909d19dd01287093f6b6271c ("ext4: avoid divide by
zero when trying to mount a corrupted file system") fixes CVE-2009-4307
by performing a sanity check on s_log_groups_per_flex, since it can be
set to a bogus value by an attacker.

	sbi->s_log_groups_per_flex = sbi->s_es->s_log_groups_per_flex;
	groups_per_flex = 1 << sbi->s_log_groups_per_flex;

	if (groups_per_flex < 2) { ... }

This patch fixes two potential issues in the previous commit.

1) The sanity check might only work on architectures like PowerPC.
On x86, 5 bits are used for the shifting amount.  That means, given a
large s_log_groups_per_flex value like 36, groups_per_flex = 1 << 36
is essentially 1 << 4 = 16, rather than 0.  This will bypass the check,
leaving s_log_groups_per_flex and groups_per_flex inconsistent.

2) The sanity check relies on undefined behavior, i.e., oversized shift.
A standard-confirming C compiler could rewrite the check in unexpected
ways.  Consider the following equivalent form, assuming groups_per_flex
is unsigned for simplicity.

	groups_per_flex = 1 << sbi->s_log_groups_per_flex;
	if (groups_per_flex == 0 || groups_per_flex == 1) {

We compile the code snippet using Clang 3.0 and GCC 4.6.  Clang will
completely optimize away the check groups_per_flex == 0, leaving the
patched code as vulnerable as the original.  GCC keeps the check, but
there is no guarantee that future versions will do the same.

Signed-off-by: Xi Wang 
Signed-off-by: "Theodore Ts'o" 
Signed-off-by: Greg Kroah-Hartman

ext4: add missing ext4_resize_end on error paths

2012-01-26T00:13:07+00:00

commit 014a1770371a028d22f364718c805f4216911ecd upstream.

Online resize ioctls 'EXT4_IOC_GROUP_EXTEND' and 'EXT4_IOC_GROUP_ADD'
call ext4_resize_begin() to check permissions and to set the
EXT4_RESIZING bit lock, they do their work and they must finish with
ext4_resize_end() which calls clear_bit_unlock() to unlock and to
avoid -EBUSY errors for the next resize operations.

This patch adds the missing ext4_resize_end() calls on error paths.

Patch tested.

Signed-off-by: Djalal Harouni 
Signed-off-by: "Theodore Ts'o" 
Signed-off-by: Greg Kroah-Hartman

ext4: handle EOF correctly in ext4_bio_write_page()

2011-12-14T03:29:12+00:00

We need to zero out part of a page which beyond EOF before setting uptodate,
otherwise, mapread or write will see non-zero data beyond EOF.

Signed-off-by: Yongqiang Yang 
Signed-off-by: "Theodore Ts'o" 
Cc: stable@kernel.org

ext4: remove a wrong BUG_ON in ext4_ext_convert_to_initialized

2011-12-14T03:13:42+00:00

If a file is fallocated on a hole, map->m_lblk + map->m_len may be greater
than ee_block + ee_len.

Signed-off-by: Yongqiang Yang 
Signed-off-by: "Theodore Ts'o" 
Cc: stable@kernel.org

ext4: correctly handle pages w/o buffers in ext4_discard_partial_buffers()

2011-12-14T03:05:05+00:00

If a page has been read into memory and never been written, it has no
buffers, but we should handle the page in truncate or punch hole.

VFS code of writing operations has handled holes correctly, so this
patch removes the code handling holes in writing operations.

Signed-off-by: Yongqiang Yang 
Signed-off-by: "Theodore Ts'o" 
Cc: stable@kernel.org