Generic inode has unused i_private pointer which may be used as cur_aio_dio
storage.

TODO: If cur_aio_dio will be passed as an argument to get_block_t this allow
      to have concurent AIO_DIO requests.
Reviewed-by: Zheng Liu <wenqing.lz@taobao.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

Previously we allocated the s_group_info array with enough space for
any future possible growth of the file system via online resize.  This
is unfortunate because it wastes memory, and it doesn't work for the
meta_bg scheme, since there is no limit based on the number of
reserved gdt blocks.  So add the code to grow the s_group_info array
as needed.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

Previously, we allocated the s_flex_groups array to the maximum size
that the file system could be resized.  There was two problems with
this approach.  First, it wasted memory in the common case where the
file system was not resized.  Secondly, once we start allowing online
resizing using the meta_bg scheme, there is no maximum size that the
file system can be resized.  So instead, we need to grow the
s_flex_groups at inline resize time.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

Currently in ext4 the length of zero-out chunk is set to 7 file system
blocks.  But if an inode has uninitailized extents from using
fallocate to preallocate space, and the workload issues many random
writes, this can cause a fragmented extent tree that will
unnecessarily grow the extent tree.

So create a new sysfs tunable, extent_max_zeroout_kb, which controls
the maximum size where blocks will be zeroed out instead of creating a
new uninitialized extent.  The default of this has been sent to 32kb.

CC: Zach Brown <zab@zabbo.net>
CC: Andreas Dilger <adilger@dilger.ca>
Signed-off-by: Zheng Liu <wenqing.lz@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

Very large directories can cause significant performance problems, or
perhaps even invoke the OOM killer, if the process is running in a
highly constrained memory environment (whether it is VM's with a small
amount of memory or in a small memory cgroup).

So it is useful, in cloud server/data center environments, to be able
to set a filesystem-wide cap on the maximum size of a directory, to
ensure that directories never get larger than a sane size.  We do this
via a new mount option, max_dir_size_kb.  If there is an attempt to
grow the directory larger than max_dir_size_kb, the system call will
return ENOSPC instead.

Google-Bug-Id: 6863013
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

The last user of ext4_mark_super_dirty() in ext4_file_open() is so
rare it can well be modifying the superblock properly by journalling
the change.  Change it and get rid of ext4_mark_super_dirty() as it's
not needed anymore.

Artem: small amendments.
Artem: tested using xfstests for both journalled and non-journalled ext4.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Tested-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>

The ext4_checksum() inline function was using a dynamic array size,
which is not legal C.  (It is a gcc extension).

Remove it.

Cc: "Darrick J. Wong" <djwong@us.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

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: Jan Kara <jack@suse.cz>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Johann Lombardi <johann@whamcloud.com>
Signed-off-by: Aditya Kali <adityakali@google.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

EXT4_GET_BLOCKS_NO_LOCK flag is added to indicate that we don't need
to acquire i_data_sem lock in ext4_map_blocks.  Meanwhile, it changes
ext4_get_block() to not start a new journal because when we do a
overwrite dio, there is no any metadata that needs to be modified.

We define a new function called ext4_get_block_write_nolock, which is
used in dio overwrite nolock.  In this function, it doesn't try to
acquire i_data_sem lock and doesn't start a new journal as it does a
lookup.

CC: Tao Ma <tm@tao.ma>
CC: Eric Sandeen <sandeen@redhat.com>
CC: Robin Dong <hao.bigrat@gmail.com>
Signed-off-by: Zheng Liu <wenqing.lz@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

Commit f975d6bc introduced bug which caused ext4_statfs() to
miscalculate the number of file system overhead blocks.  This causes
the f_blocks field in the statfs structure to be larger than it should
be.  This would in turn cause the "df" output to show the number of
data blocks in the file system and the number of data blocks used to
be larger than they should be.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@kernel.org

Make it possible for ext4_count_free to operate on buffers and not
just data in buffer_heads.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@kernel.org

Make it easy to test whether or not the error handling subsystem in
ext4 is working correctly.  This allows us to simulate an ext4_error()
by echoing a string to /sys/fs/ext4/<dev>/trigger_fs_error.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: ksumrall@google.com

needs_recovery in ext4_mb_init() is not used, remove it.
Signed-off-by: Akira Fujita <a-fujita@rs.jp.ne.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

Activate the metadata checksumming feature by adding it to ext4 and
jbd2's lists of supported features.
Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

Compute and verify a checksum for the MMP block.
Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

metadata_csum supersedes uninit_bg.  Convert the ROCOMPAT uninit_bg
flag check to a helper function that covers both, and make the
checksum calculation algorithm use either crc16 or the metadata_csum
chosen algorithm depending on which flag is set.  Print a warning if
we try to mount a filesystem with both feature flags set.
Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

Calculate and verify the checksums for directory leaf blocks
(i.e. blocks that only contain actual directory entries).  The
checksum lives in what looks to be an unused directory entry with a 0
name_len at the end of the block.  This scheme is not used for
internal htree nodes because the mechanism in place there only costs
one dx_entry, whereas the "empty" directory entry would cost two
dx_entries.
Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

Compute and verify the checksum of the block bitmap; this checksum is
stored in the block group descriptor.
Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

Compute and verify the checksum of the inode bitmap; the checkum is
stored in the block group descriptor.
Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

This patch introduces to ext4 the ability to calculate and verify
inode checksums.  This requires the use of a new ro compatibility flag
and some accompanying e2fsprogs patches to provide the relevant
features in tune2fs and e2fsck.  The inode generation changes have
been integrated into this patch.
Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: "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: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

Obtain a reference to the cryptoapi and crc32c if we mount a
filesystem with metadata checksumming enabled.
Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

Define flags and change structure definitions to allow checksumming of
ext4 metadata.
Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

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" <tytso@mit.edu>
Cc: stable@vger.kernel.org

Add argument validation to debug functions.
Use ##__VA_ARGS__.

Fix format and argument mismatches.
Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

Traditionally ext2/3/4 has returned a 32-bit hash value from llseek()
to appease NFSv2, which can only handle a 32-bit cookie for seekdir()
and telldir().  However, this causes problems if there are 32-bit hash
collisions, since the NFSv2 server can get stuck resending the same
entries from the directory repeatedly.

Allow ext4 to return a full 64-bit hash (both major and minor) for
telldir to decrease the chance of hash collisions.  This still needs
integration on the NFS side.
Patch-updated-by: Bernd Schubert <bernd.schubert@itwm.fraunhofer.de>
(blame me if something is not correct)
Signed-off-by: Fan Yong <yong.fan@whamcloud.com>
Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Signed-off-by: Bernd Schubert <bernd.schubert@itwm.fraunhofer.de>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

This should make it more clear what this structure is used
for, and how some of the (mutually exclusive) fields are
used to keep page cache references.
Signed-off-by: Curt Wohlgemuth <curtw@google.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

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 b82e384c ("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 <jmoyer@redhat.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
CC: stable@kernel.org

Consistently show mount options which are the non-default, so that
/proc/mounts accurately shows the mount options that would be
necessary to mount the file system in its current mode of operation.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

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

There's no point to have two bits that are set in parallel; so use the
MS_I_VERSION flag that is needed by the VFS anyway, and that way we
free up a bit in sbi->s_mount_opts.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

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 <jack@suse.cz>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@vger.kernel.org

In commit 9b90e5e0 I incorrectly reserved the wrong bit for
EXT4_FEATURE_INCOMPAT_INLINEDATA per the discussion on the linux-ext4
list on December 7, 2011.  The codepoint 0x2000 should be used for
EXT4_FEATURE_INCOMPAT_USE_META_CSUM, so INLINEDATA will be assigned
the value 0x8000.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

In ext4_read_{inode,block}_bitmap() we were setting bitmap_uptodate()
before submitting the buffer for read.  The is bad, since we check
bitmap_uptodate() without locking the buffer, and so if another
process is racing with us, it's possible that they will think the
bitmap is uptodate even though the read has not completed yet,
resulting in inodes and blocks potentially getting allocated more than
once if we get really unlucky.

Addresses-Google-Bug: 2828254
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

A couple more functions can reasonably be made static if desired.
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

Reserve the ext4 features flags EXT4_FEATURE_RO_COMPAT_METADATA_CSUM,
EXT4_FEATURE_INCOMPAT_INLINEDATA, and EXT4_FEATURE_INCOMPAT_LARGEDIR.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

This patch adds new online resize interface, whose input argument is a
64-bit integer indicating how many blocks there are in the resized fs.

In new resize impelmentation, all work like allocating group tables
are done by kernel side, so the new resize interface can support
flex_bg feature and prepares ground for suppoting resize with features
like bigalloc and exclude bitmap. Besides these, user-space tools just
passes in the new number of blocks.

We delay initializing the bitmaps and inode tables of added groups if
possible and add multi groups (a flex groups) each time, so new resize
is very fast like mkfs.
Signed-off-by: Yongqiang Yang <xiaoqiangnk@gmail.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

This patch adds a function named setup_new_flex_group_blocks() which
sets up group blocks of a flex bg.
Signed-off-by: Yongqiang Yang <xiaoqiangnk@gmail.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>