We see the following NULL pointer dereference while running xfstests
generic/475:
BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
PGD 8000000c84bad067 P4D 8000000c84bad067 PUD c84e62067 PMD 0
Oops: 0000 [#1] SMP PTI
CPU: 7 PID: 9886 Comm: fsstress Kdump: loaded Not tainted 5.0.0-rc8 #10
RIP: 0010:ext4_do_update_inode+0x4ec/0x760
...
Call Trace:
? jbd2_journal_get_write_access+0x42/0x50
? __ext4_journal_get_write_access+0x2c/0x70
? ext4_truncate+0x186/0x3f0
ext4_mark_iloc_dirty+0x61/0x80
ext4_mark_inode_dirty+0x62/0x1b0
ext4_truncate+0x186/0x3f0
? unmap_mapping_pages+0x56/0x100
ext4_setattr+0x817/0x8b0
notify_change+0x1df/0x430
do_truncate+0x5e/0x90
? generic_permission+0x12b/0x1a0

This is triggered because the NULL pointer handle->h_transaction was
dereferenced in function ext4_update_inode_fsync_trans().
I found that the h_transaction was set to NULL in jbd2__journal_restart
but failed to attached to a new transaction while the journal is aborted.

Fix this by checking the handle before updating the inode.

Fixes: b436b9be ("ext4: Wait for proper transaction commit on fsync")
Signed-off-by: NJiufei Xue <jiufei.xue@linux.alibaba.com>
Signed-off-by: NTheodore Ts'o <tytso@mit.edu>
Reviewed-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Cc: stable@kernel.org

This commit removes the ext4 specific ext4_encrypted_inode() and makes
use of the generic IS_ENCRYPTED() macro to check for the encryption
status of an inode.
Reviewed-by: NEric Biggers <ebiggers@google.com>
Signed-off-by: NChandan Rajendra <chandan@linux.vnet.ibm.com>
Signed-off-by: NEric Biggers <ebiggers@google.com>

A number of ext4 source files were skipped due because their copyright
permission statements didn't match the expected text used by the
automated conversion utilities.  I've added SPDX tags for the rest.

While looking at some of these files, I've noticed that we have quite
a bit of variation on the licenses that were used --- in particular
some of the Red Hat licenses on the jbd2 files use a GPL2+ license,
and we have some files that have a LGPL-2.1 license (which was quite
surprising).

I've not attempted to do any license changes.  Even if it is perfectly
legal to relicense to GPL 2.0-only for consistency's sake, that should
be done with ext4 developer community discussion.
Signed-off-by: NTheodore Ts'o <tytso@mit.edu>

When upgrading from old format, try to set project id
to old file first time, it will return EOVERFLOW, but if
that file is dirtied(touch etc), changing project id will
be allowed, this might be confusing for users, we could
try to expand @i_extra_isize here too.
Reported-by: NZhang Yi <yi.zhang@huawei.com>
Signed-off-by: NMiao Xie <miaoxie@huawei.com>
Signed-off-by: NWang Shilong <wshilong@ddn.com>
Signed-off-by: NTheodore Ts'o <tytso@mit.edu>

Both ext4_set_acl() and ext4_set_context() need to be made aware of
ea_inode feature when it comes to credits calculation.

Also add a sufficient credits check in ext4_xattr_set_handle() right
after xattr write lock is grabbed. Original credits calculation is done
outside the lock so there is a possiblity that the initially calculated
credits are not sufficient anymore.
Signed-off-by: NTahsin Erdogan <tahsin@google.com>
Signed-off-by: NTheodore Ts'o <tytso@mit.edu>

This INCOMPAT_LARGEDIR feature allows larger directories to be created
in ldiskfs, both with directory sizes over 2GB and and a maximum htree
depth of 3 instead of the current limit of 2. These features are needed
in order to exceed the current limit of approximately 10M entries in a
single directory.

This patch was originally written by Yang Sheng to support the Lustre server.

[ Bumped the credits needed to update an indexed directory -- tytso ]
Signed-off-by: NLiang Zhen <liang.zhen@intel.com>
Signed-off-by: NYang Sheng <yang.sheng@intel.com>
Signed-off-by: NArtem Blagodarenko <artem.blagodarenko@seagate.com>
Signed-off-by: NTheodore Ts'o <tytso@mit.edu>
Reviewed-by: NAndreas Dilger <andreas.dilger@intel.com>

Currently data journalling is incompatible with encryption: enabling both
at the same time has never been supported by design, and would result in
unpredictable behavior. However, users are not precluded from turning on
both features simultaneously. This change programmatically replaces data
journaling for encrypted regular files with ordered data journaling mode.

Background:
Journaling encrypted data has not been supported because it operates on
buffer heads of the page in the page cache. Namely, when the commit
happens, which could be up to five seconds after caching, the commit
thread uses the buffer heads attached to the page to copy the contents of
the page to the journal. With encryption, it would have been required to
keep the bounce buffer with ciphertext for up to the aforementioned five
seconds, since the page cache can only hold plaintext and could not be
used for journaling. Alternatively, it would be required to setup the
journal to initiate a callback at the commit time to perform deferred
encryption - in this case, not only would the data have to be written
twice, but it would also have to be encrypted twice. This level of
complexity was not justified for a mode that in practice is very rarely
used because of the overhead from the data journalling.

Solution:
If data=journaled has been set as a mount option for a filesystem, or if
journaling is enabled on a regular file, do not perform journaling if the
file is also encrypted, instead fall back to the data=ordered mode for the
file.

Rationale:
The intent is to allow seamless and proper filesystem operation when
journaling and encryption have both been enabled, and have these two
conflicting features gracefully resolved by the filesystem.

Fixes: 44614711Signed-off-by: NSergey Karamov <skaramov@google.com>
Signed-off-by: NTheodore Ts'o <tytso@mit.edu>
Cc: stable@vger.kernel.org

If there are no pending blocks to be released after a commit, forcing
a journal commit has no hope of helping.  It's possible that a commit
had just completed, so if there are now free blocks available for
allocation, it's worth retrying the commit.
Reported-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NTheodore Ts'o <tytso@mit.edu>

Currently we ask jbd2 to write all dirty allocated buffers before
committing a transaction when doing writeback of delay allocated blocks.
However this is unnecessary since we move all pages to writeback state
before dropping a transaction handle and then submit all the necessary
IO. We still need the transaction commit to wait for all the outstanding
writeback before flushing disk caches during transaction commit to avoid
data exposure issues though. Use the new jbd2 capability and ask it to
only wait for outstanding writeback during transaction commit when
writing back data in ext4_writepages().
Tested-by: N"HUANG Weller (CM/ESW12-CN)" <Weller.Huang@cn.bosch.com>
Signed-off-by: NJan Kara <jack@suse.cz>
Signed-off-by: NTheodore Ts'o <tytso@mit.edu>

Currently when filesystem needs to make sure data is on permanent
storage before committing a transaction it adds inode to transaction's
inode list. During transaction commit, jbd2 writes back all dirty
buffers that have allocated underlying blocks and waits for the IO to
finish. However when doing writeback for delayed allocated data, we
allocate blocks and immediately submit the data. Thus asking jbd2 to
write dirty pages just unnecessarily adds more work to jbd2 possibly
writing back other redirtied blocks.

Add support to jbd2 to allow filesystem to ask jbd2 to only wait for
outstanding data writes before committing a transaction and thus avoid
unnecessary writes.
Signed-off-by: NJan Kara <jack@suse.cz>
Signed-off-by: NTheodore Ts'o <tytso@mit.edu>

Create separate predicate functions to test/set/clear feature flags,
thereby replacing the wordy old macros.  Furthermore, clean out the
places where we open-coded feature tests.
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>

MAXQUOTAS value defines maximum number of quota types VFS supports.
This isn't necessarily the number of types ext4 supports. Although
ext4 will support project quotas, use ext4 private definition for
consistency with other filesystems.
Signed-off-by: NJan Kara <jack@suse.cz>
Signed-off-by: NTheodore Ts'o <tytso@mit.edu>

I have been running make namespacecheck to look for unneeded globals, and
found these in ext4.
Signed-off-by: NStephen Hemminger <stephen@networkplumber.org>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

Signed-off-by: NAnatol Pomozov <anatol.pomozov@gmail.com>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

Later we would like to clear PageWriteback bit only after extent
conversion from unwritten to written extents is performed.  However it
is not possible to start a transaction after PageWriteback is set
because that violates lock ordering (and is easy to deadlock).  So we
have to reserve a transaction before locking pages and sending them
for IO and later we use the transaction for extent conversion from
ext4_end_io().
Reviewed-by: NZheng Liu <wenqing.lz@taobao.com>
Signed-off-by: NJan Kara <jack@suse.cz>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

Reviewed-by: NZheng Liu <wenqing.lz@taobao.com>
Signed-off-by: NJan Kara <jack@suse.cz>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

Estimate of 27 credits for allocation of a block in extent based inode
is unnecessarily high. We can easily argue 20 is enough.
Signed-off-by: NJan Kara <jack@suse.cz>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

It is incorrect to use list_for_each_entry_safe() for journal callback
traversial because ->next may be removed by other task:
->ext4_mb_free_metadata()
  ->ext4_mb_free_metadata()
    ->ext4_journal_callback_del()

This results in the following issue:

WARNING: at lib/list_debug.c:62 __list_del_entry+0x1c0/0x250()
Hardware name:
list_del corruption. prev->next should be ffff88019a4ec198, but was 6b6b6b6b6b6b6b6b
Modules linked in: cpufreq_ondemand acpi_cpufreq freq_table mperf coretemp kvm_intel kvm crc32c_intel ghash_clmulni_intel microcode sg xhci_hcd button sd_mod crc_t10dif aesni_intel ablk_helper cryptd lrw aes_x86_64 xts gf128mul ahci libahci pata_acpi ata_generic dm_mirror dm_region_hash dm_log dm_mod
Pid: 16400, comm: jbd2/dm-1-8 Tainted: G        W    3.8.0-rc3+ #107
Call Trace:
 [<ffffffff8106fb0d>] warn_slowpath_common+0xad/0xf0
 [<ffffffff8106fc06>] warn_slowpath_fmt+0x46/0x50
 [<ffffffff813637e9>] ? ext4_journal_commit_callback+0x99/0xc0
 [<ffffffff8148cae0>] __list_del_entry+0x1c0/0x250
 [<ffffffff813637bf>] ext4_journal_commit_callback+0x6f/0xc0
 [<ffffffff813ca336>] jbd2_journal_commit_transaction+0x23a6/0x2570
 [<ffffffff8108aa42>] ? try_to_del_timer_sync+0x82/0xa0
 [<ffffffff8108b491>] ? del_timer_sync+0x91/0x1e0
 [<ffffffff813d3ecf>] kjournald2+0x19f/0x6a0
 [<ffffffff810ad630>] ? wake_up_bit+0x40/0x40
 [<ffffffff813d3d30>] ? bit_spin_lock+0x80/0x80
 [<ffffffff810ac6be>] kthread+0x10e/0x120
 [<ffffffff810ac5b0>] ? __init_kthread_worker+0x70/0x70
 [<ffffffff818ff6ac>] ret_from_fork+0x7c/0xb0
 [<ffffffff810ac5b0>] ? __init_kthread_worker+0x70/0x70

This patch fix the issue as follows:
- ext4_journal_commit_callback() make list truly traversial safe
  simply by always starting from list_head
- fix race between two ext4_journal_callback_del() and
  ext4_journal_callback_try_del()
Signed-off-by: NDmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>
Reviewed-by: NJan Kara <jack@suse.cz>
Cc: stable@vger.kernel.com

Operations which modify extended attributes may need extra journal
credits if inline data is used, since there is a chance that some
extended attributes may need to get pushed to an external attribute
block.

Changes to reflect this was made in xattr.c, but they were missed in
fs/ext4/acl.c.  To fix this, abstract the calculation of the number of
credits needed for xattr operations to an inline function defined in
ext4_jbd2.h, and use it in acl.c and xattr.c.

Also move the function declarations used in inline.c from xattr.h
(where they are non-obviously hidden, and caused problems since
ext4_jbd2.h needs to use the function ext4_has_inline_data), and move
them to ext4.h.
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>
Reviewed-by: NTao Ma <boyu.mt@taobao.com>
Reviewed-by: NJan Kara <jack@suse.cz>

The ext4_unlink() and ext4_rmdir() don't actually release the blocks
associated with the file/directory.  This gets done in a separate jbd2
handle called via ext4_evict_inode().  Thus, we don't need to reserve
lots of journal credits for the truncate.

Note that using too many journal credits is non-optimal because it can
leading to the journal transmit getting closed too early, before it is
strictly necessary.
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>
Reviewed-by: NJan Kara <jack@suse.cz>

So we can better understand what bits of ext4 are responsible for
long-running jbd2 handles, use jbd2__journal_start() so we can pass
context information for logging purposes.

The recommended way for finding the longer-running handles is:

   T=/sys/kernel/debug/tracing
   EVENT=$T/events/jbd2/jbd2_handle_stats
   echo "interval > 5" > $EVENT/filter
   echo 1 > $EVENT/enable

   ./run-my-fs-benchmark

   cat $T/trace > /tmp/problem-handles

This will list handles that were active for longer than 20ms.  Having
longer-running handles is bad, because a commit started at the wrong
time could stall for those 20+ milliseconds, which could delay an
fsync() or an O_SYNC operation.  Here is an example line from the
trace file describing a handle which lived on for 311 jiffies, or over
1.2 seconds:

postmark-2917  [000] ....   196.435786: jbd2_handle_stats: dev 254,32 
   tid 570 type 2 line_no 2541 interval 311 sync 0 requested_blocks 1
   dirtied_blocks 0
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

ext4_handle_release_buffer() was intended to remove journal
write access from a buffer, but it doesn't actually do anything
at all other than add a BUFFER_TRACE point, but it's not reliably
used for that either.  Remove all the associated dead code.
Signed-off-by: NEric Sandeen <sandeen@redhat.com>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>
Reviewed-by: NCarlos Maiolino <cmaiolino@redhat.com>

The '__ext4_handle_dirty_metadata()' does not need the 'now' argument
anymore and we can kill it.
Signed-off-by: NArtem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>
Reviewed-by: NJan Kara <jack@suse.cz>

This patch adds support for quotas as a first class feature in ext4;
which is to say, the quota files are stored in hidden inodes as file
system metadata, instead of as separate files visible in the file system
directory hierarchy.

It is based on the proposal at:                                                                                                           
https://ext4.wiki.kernel.org/index.php/Design_For_1st_Class_Quota_in_Ext4

This patch introduces a new feature - EXT4_FEATURE_RO_COMPAT_QUOTA
which, when turned on, enables quota accounting at mount time
iteself. Also, the quota inodes are stored in two additional superblock
fields.  Some changes introduced by this patch that should be pointed
out are:

1) Two new ext4-superblock fields - s_usr_quota_inum and
   s_grp_quota_inum for storing the quota inodes in use.
2) Default quota inodes are: inode#3 for tracking userquota and inode#4
   for tracking group quota. The superblock fields can be set to use
   other inodes as well.
3) If the QUOTA feature and corresponding quota inodes are set in
   superblock, the quota usage tracking is turned on at mount time. On
   'quotaon' ioctl, the quota limits enforcement is turned
   on. 'quotaoff' ioctl turns off only the limits enforcement in this
   case.
4) When QUOTA feature is in use, the quota mount options 'quota',
   'usrquota', 'grpquota' are ignored by the kernel.
5) mke2fs or tune2fs can be used to set the QUOTA feature and initialize
   quota inodes. The default reserved inodes will not be visible to user
   as regular files.
6) The quota-tools will need to be modified to support hidden quota
   files on ext4. E2fsprogs will also include support for creating and
   fixing quota files.
7) Support is only for the new V2 quota file format.
Tested-by: NJan Kara <jack@suse.cz>
Reviewed-by: NJan Kara <jack@suse.cz>
Reviewed-by: NJohann Lombardi <johann@whamcloud.com>
Signed-off-by: NAditya Kali <adityakali@google.com>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

Calculate and verify the superblock checksum.  Since the UUID and
block group number are embedded in each copy of the superblock, we
need only checksum the entire block.  Refactor some of the code to
eliminate open-coding of the checksum update call.
Signed-off-by: NDarrick J. Wong <djwong@us.ibm.com>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

The per-commit callback was used by mballoc code to manage free space
bitmaps after deleted blocks have been released.  This patch expands
it to support multiple different callbacks, to allow other things to
be done after the commit has been completed.
Signed-off-by: NBobi Jam <bobijam@whamcloud.com>
Signed-off-by: NAndreas Dilger <adilger@whamcloud.com>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

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: NLukas Czerner <lczerner@redhat.com>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>
Cc: stable@vger.kernel.org

ext4_should_writeback_data() had an incorrect sequence of
tests to determine if it should return 0 or 1: in
particular, even in no-journal mode, 0 was being returned
for a non-regular-file inode.

This meant that, in non-journal mode, we would use
ext4_journalled_aops for directories, symlinks, and other
non-regular files.  However, calling journalled aop
callbacks when there is no valid handle, can cause problems.

This would cause a kernel crash with Jan Kara's commit
2d859db3 ("ext4: fix data corruption in inodes with
journalled data"), because we now dereference 'handle' in
ext4_journalled_write_end().

I also added BUG_ONs to check for a valid handle in the
obviously journal-only aops callbacks.

I tested this running xfstests with a scratch device in
these modes:

   - no-journal
   - data=ordered
   - data=writeback
   - data=journal

All work fine; the data=journal run has many failures and a
crash in xfstests 074, but this is no different from a
vanilla kernel.
Signed-off-by: NCurt Wohlgemuth <curtw@google.com>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>
Cc: stable@kernel.org

The block allocation code used to use jbd2_journal_get_undo_access as
a way to make changes that wouldn't show up until the commit took
place.  The new multi-block allocation code has a its own way of
preventing newly freed blocks from getting reused until the commit
takes place (it avoids updating the buddy bitmaps until the commit is
done), so we don't need to use jbd2_journal_get_undo_access(), which
has extra overhead compared to jbd2_journal_get_write_access().

There was one last vestigal use of ext4_journal_get_undo_access() in
ext4_add_groupblocks(); change it to use ext4_journal_get_write_access()
and then remove the ext4_journal_get_undo_access() support.
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

It is not necessary to update [cm]time of quota file on each quota
file write and it wastes journal space and IO throughput with inode
writes. So just remove the updating from ext4_quota_write() and only
update times when quotas are being turned off. Userspace cannot get
anything reliable from quota files while they are used by the kernel
anyway.
Signed-off-by: NJan Kara <jack@suse.cz>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

There are two wrapper functions which do exactly the same thing:
ext4_journal_release_buffer(), and ext4_handle_release_buffer().  In
addition, ext4_xattr_block_set() calls jbd2_journal_release_buffer()
directly.

Unify all of the code to use ext4_handle_release_buffer(), and get rid
of ext4_journal_release_buffer().
Signed-off-by: NAmir Goldstein <amir73il@users.sf.net>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

Replace the jbd2_inode structure (which is 48 bytes) with a pointer
and only allocate the jbd2_inode when it is needed --- that is, when
the file system has a journal present and the inode has been opened
for writing.  This allows us to further slim down the ext4_inode_info
structure.
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

This allows the error messages to include the line number
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

The nobh option was only supported for writeback mode, but given that all
write paths actually create buffer heads it effectively was a no-op already.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

We don't need to set s_dirt in most of the ext4 code when journaling
is enabled.  In ext3/4 some of the summary statistics for # of free
inodes, blocks, and directories are calculated from the per-block
group statistics when the file system is mounted or unmounted.  As a
result the superblock doesn't have to be updated, either via the
journal or by setting s_dirt.  There are a few exceptions, most
notably when resizing the file system, where the superblock needs to
be modified --- and in that case it should be done as a journalled
operation if possible, and s_dirt set only in no-journal mode.

This patch will optimize out some unneeded disk writes when using ext4
with a journal.
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

At several places we modify EXT4_I(inode)->i_flags without holding
i_mutex (ext4_do_update_inode, ...). These modifications are racy and
we can lose updates to i_flags. So convert handling of i_flags to use
bitops which are atomic.

https://bugzilla.kernel.org/show_bug.cgi?id=15792Signed-off-by: NDmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

Allocate uninitialized extent before ext4 buffer write and
convert the extent to initialized after io completes.
The purpose is to make sure an extent can only be marked
initialized after it has been written with new data so
we can safely drop the i_mutex lock in ext4 DIO read without
exposing stale data. This helps to improve multi-thread DIO
read performance on high-speed disks.

Skip the nobh and data=journal mount cases to make things simple for now.
Signed-off-by: NJiaying Zhang <jiayingz@google.com>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

We cannot rely on buffer dirty bits during fsync because pdflush can come
before fsync is called and clear dirty bits without forcing a transaction
commit. What we do is that we track which transaction has last changed
the inode and which transaction last changed allocation and force it to
disk on fsync.
Signed-off-by: NJan Kara <jack@suse.cz>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

Currently all quota block reservation macros contains hard-coded "2"
aka MAXQUOTAS value. This is no good because in some places it is not
obvious to understand what does this digit represent. Let's introduce
new macro with self descriptive name.
Signed-off-by: NDmitry Monakhov <dmonakhov@openvz.org>
Acked-by: NMingming Cao <cmm@us.ibm.com>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>