When trying to mount a file system which does not contain a journal,
but which does have a orphan list containing an inode which needs to
be truncated, the mount call with hang forever in
ext4_orphan_cleanup() because ext4_orphan_del() will return
immediately without removing the inode from the orphan list, leading
to an uninterruptible loop in kernel code which will busy out one of
the CPU's on the system.

This can be trivially reproduced by trying to mount the file system
found in tests/f_orphan_extents_inode/image.gz from the e2fsprogs
source tree.  If a malicious user were to put this on a USB stick, and
mount it on a Linux desktop which has automatic mounts enabled, this
could be considered a potential denial of service attack.  (Not a big
deal in practice, but professional paranoids worry about such things,
and have even been known to allocate CVE numbers for such problems.)
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Reviewed-by: Zheng Liu <wenqing.lz@taobao.com>
Cc: stable@vger.kernel.org

Commit c278531d added a warning when ext4_flush_unwritten_io() is
called without i_mutex being taken.  It had previously not been taken
during orphan cleanup since races weren't possible at that point in
the mount process, but as a result of this c278531d, we will now see
a kernel WARN_ON in this case.  Take the i_mutex in
ext4_orphan_cleanup() to suppress this warning.
Reported-by: Alexander Beregalov <a.beregalov@gmail.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Reviewed-by: Zheng Liu <wenqing.lz@taobao.com>
Cc: stable@vger.kernel.org

When a journal-less ext4 filesystem is mounted on a read-only block
device (blockdev --setro will do), each remount (for other, unrelated,
flags, like suid=>nosuid etc) results in a series of scary messages
from kernel telling about I/O errors on the device.

This is becauese of the following code ext4_remount():

       if (sbi->s_journal == NULL)
                ext4_commit_super(sb, 1);

at the end of remount procedure, which forces writing (flushing) of
a superblock regardless whenever it is dirty or not, if the filesystem
is readonly or not, and whenever the device itself is readonly or not.

We only need call ext4_commit_super when the file system had been
previously mounted read/write.

Thanks to Eric Sandeen for help in diagnosing this issue.
Signed-off-By: Michael Tokarev <mjt@tls.msk.ru>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@vger.kernel.org

To more accurately calculate overhead for "bsd" style
df reporting, we should count the journal blocks as
overhead as well.
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Tested-by: Eric Whitney <enwlinux@gmail.com>

Although I put this in, I now think it was a bad decision.  For most
users, there is very little to be done in this case.  They get the
message, once per day, with no real context or proposed action.  TBH,
it generates support calls when it probably does not need to; the
message sounds more dire than the situation really is.

Just nuke it.  Normal investigation via blktrace or whatnot can
reveal poor IO patterns if bad performance is encountered.
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

i_mutex is not held when ->sync_file is called.
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

We cannot wait for transaction commit in journal_unmap_buffer()
because we hold page lock which ranks below transaction start.  We
solve the issue by bailing out of journal_unmap_buffer() and
jbd2_journal_invalidatepage() with -EBUSY.  Caller is then responsible
for waiting for transaction commit to finish and try invalidation
again. Since the issue can happen only for page stradding i_size, it
is simple enough to manually call jbd2_journal_invalidatepage() for
such page from ext4_setattr(), check the return value and wait if
necessary.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

In data=journal mode we don't need delalloc or DIO handling in invalidatepage
and similarly in other modes we don't need the journal handling. So split
invalidatepage implementations.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

The following race is possible between start_this_handle() and someone
calling jbd2_journal_flush().

Process A                              Process B
start_this_handle().
  if (journal->j_barrier_count) # false
  if (!journal->j_running_transaction) { #true
    read_unlock(&journal->j_state_lock);
                                       jbd2_journal_lock_updates()
                                       jbd2_journal_flush()
                                         write_lock(&journal->j_state_lock);
                                         if (journal->j_running_transaction) {
                                           # false
                                         ... wait for committing trans ...
                                         write_unlock(&journal->j_state_lock);
    ...
    write_lock(&journal->j_state_lock);
    if (!journal->j_running_transaction) { # true
      jbd2_get_transaction(journal, new_transaction);
    write_unlock(&journal->j_state_lock);
    goto repeat; # eventually blocks on j_barrier_count > 0
                                         ...
                                         J_ASSERT(!journal->j_running_transaction);
                                           # fails

We fix the race by rechecking j_barrier_count after reacquiring j_state_lock
in exclusive mode.

Reported-by: yjwsignal@empal.com
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@vger.kernel.org

Currently we allow enabling dioread_nolock mount option on remount for
filesystems where blocksize < PAGE_CACHE_SIZE.  This isn't really
supported so fix the bug by moving the check for blocksize !=
PAGE_CACHE_SIZE into parse_options(). Change the original PAGE_SIZE to
PAGE_CACHE_SIZE along the way because that's what we are really
interested in.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
Cc: stable@vger.kernel.org

When depth of extent tree is greater than 1, logical start value of
interior node is not correctly updated in ext4_ext_rm_idx.
Signed-off-by: Forrest Liu <forrestl@synology.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Reviewed-by: Ashish Sangwan <ashishsangwan2@gmail.com>
Cc: stable@vger.kernel.org

Not all architectures (in particular, sparc64) have empty_zero_page.
So instead of copying from empty_zero_page, use memset to clear the
inline data by signalling to ext4_xattr_set_entry() via a magic
pointer value, EXT4_ZERO_ATTR_VALUE, which is defined by casting -1 to
a pointer.

This fixes a build failure on sparc64, and the memset() should be more
efficient than using memcpy() anyway.
Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

Flags being used by atomic operations in inode flags (e.g.
ext4_test_inode_flag(), should be consistent with that actually stored
in inodes, i.e.: EXT4_XXX_FL.

It ensures that this consistency is checked at build-time, not at
run-time.

Currently, the flags consistency are being checked at run-time, but,
there is no real reason to not do a build-time check instead of a
run-time check. The code is comparing macro defined values with enum
type variables, where both are constants, so, there is no problem in
comparing constants at build-time.

enum variables are treated as constants by the C compiler, according
to the C99 specs (see www.open-std.org/jtc1/sc22/wg14/www/docs/n1124.pdf 
sec. 6.2.5, item 16), so, there is no real problem in comparing an
enumeration type at build time
Signed-off-by: Carlos Maiolino <cmaiolino@redhat.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

Ted has sent out a RFC about removing this feature. Eric and Jan
confirmed that both RedHat and SUSE enable this feature in all their
product.  David also said that "As far as I know, it's enabled in all
Android kernels that use ext4."  So it seems OK for us.

And what's more, as inline data depends its implementation on xattr,
and to be frank, I don't run any test again inline data enabled while
xattr disabled.  So I think we should add inline data and remove this
config option in the same release.

[ The savings if you disable CONFIG_EXT4_FS_XATTR is only 27k, which
  isn't much in the grand scheme of things.  Since no one seems to be
  testing this configuration except for some automated compile farms, on
  balance we are better removing this config option, and so that it is
  effectively always enabled. -- tytso ]

Cc: David Brown <davidb@codeaurora.org>
Cc: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Zhi Yong Wu <wuzhy@linux.vnet.ibm.com>
Reviewed-by: Zheng Liu <gnehzuil.liu@gmail.com>

We use kzalloc() to allocate sbi, no need to zero its field.
Signed-off-by: Guo Chao <yan@linux.vnet.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

inode_init_always() will initialize inode->i_data.writeback_index
anyway, no need to do this in ext4_alloc_inode().
Signed-off-by: Guo Chao <yan@linux.vnet.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Reviewed-by: Lukas Czerner <lczerner@redhat.com>

We have a dedicated interface to sync inode metadata.  Use it to
simplify ext4's code some.
Signed-off-by: Guo Chao <yan@linux.vnet.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Reviewed-by: Lukas Czerner <lczerner@redhat.com>

Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

If we are punching hole in a file, we will return ENOTSUPP.
As for the fallocation of some extents, we will convert the
inline data to a normal extent based file first.
Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

Signed-off-by: Robin Dong <sanbai@taobao.com>
Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

Now we that store data in the inode, in case we need to store some
xattrs and inode doesn't have enough space, Andreas suggested that we
should keep the xattr(metadata) in and data should be pushed out.  So
this patch does the work.
Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

fiemap is used to find the disk layout of a file, as for inline data,
let us just pretend like a file with just one extent.
Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

In case we rename a directory, ext4_rename has to read the dir block
and change its dotdot's information.  The old ext4_rename encapsulated
the dir_block read into itself.  So this patch adds a new function
ext4_get_first_dir_block() which gets the dir buffer information so
the ext4_rename can handle it properly.  As it will also change the
parent inode number, we return the parent_de so that ext4_rename() can
handle it more easily.

ext4_find_entry is also changed so that the caller(rename) can tell
whether the found entry is an inlined one or not and journaling the
corresponding buffer head.
Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

empty_dir is used when deleting a dir.  So it should handle inline dir
properly.
Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

Currently ext4_delete_entry() is used only for dir entry removing from
a dir block.  So let us create a new function
ext4_generic_delete_entry and this function takes a entry_buf and a
buf_size so that it can be used for inline data.
Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

Create a new function ext4_find_inline_entry() to handle the case of
inline data.
Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

search_dirblock is used to search a dir block, but the code is almost
the same for searching an inline dir.

So create a new fuction search_dir and let search_dirblock call it.
Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

For "." and "..", we just call filldir by ourselves
instead of iterating the real dir entry.
Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

This patch let add_dir_entry handle the inline data case. So the
dir is initialized as inline dir first and then we can try to add
some files to it, when the inline space can't hold all the entries,
a dir block will be created and the dir entry will be moved to it.

Also for an inlined dir, "." and ".." are removed and we only use
4 bytes to store the parent inode number. These 2 entries will be
added when we convert an inline dir to a block-based one.

[ Folded in patch from Dan Carpenter to remove an unused variable. ]
Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

The old add_dirent_to_buf handles all the work related to the
work of adding dir entry to a dir block. Now we have inline data,
so create 2 new function __ext4_find_dest_de and __ext4_insert_dentry
that do the real work and let add_dirent_to_buf call them.
Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

The __ext4_check_dir_entry() function() is used to check whether the
de is over the block boundary.  Now with inline data, it could be
within the block boundary while exceeds the inode size.  So check this
function to check the overflow more precisely.
Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

Currently, the initialization of dot and dotdot are encapsulated in
ext4_mkdir and also bond with dir_block. So create a new function
named ext4_init_new_dir and the initialization is moved to
ext4_init_dot_dotdot. Now it will called either in the normal non-inline
case(rec_len of ".." will cover the whole block) or when we converting an
inline dir to a block(rec len of ".." will be the real length). The start
of the next entry is also returned for inline dir usage.
Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

For delayed allocation mode, we write to inline data if the file
is small enough. And in case of we write to some offset larger
than the inline size, the 1st page is dirtied, so that
ext4_da_writepages can handle the conversion. When the 1st page
is initialized with blocks, the inline part is removed.
Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

For a normal write case (not journalled write, not delayed
allocation), we write to the inline if the file is small and convert
it to an extent based file when the write is larger than the max
inline size.
Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

Let readpage and readpages handle the case when we want to read an
inlined file.
Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

Implement inline data with xattr.

Now we use "system.data" to store xattr, and the xattr will
be extended if the i_size is increased while we don't release
the space during truncate.
Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

The inline data feature will need some inline xattr functions, so
export them from fs/ext4/xattr.c so that inline.c can use them.
Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>