If the destination of the rename(2) system call exists, the inode's
link count (i_nlinks) must be non-zero.  If it is, the inode can end
up on the orphan list prematurely, leading to all sorts of hilarity,
including a use-after-free.

https://bugzilla.kernel.org/show_bug.cgi?id=200931Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reported-by: Wen Xu <wen.xu@gatech.edu>
Cc: stable@vger.kernel.org

This suppresses some false positives in gcc 8's -Wstringop-truncation

Suggested by Miguel Ojeda (hopefully the __nonstring definition will
eventually get accepted in the compiler-gcc.h header file).
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>

The err is not used after initalization. So just remove the variable.
Signed-off-by: zhong jiang <zhongjiang@huawei.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

Merge the duplicated complex conditions to improve code readability.
Signed-off-by: Liu Song <liu.song11@zte.com.cn>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Jiang Biao <jiang.biao2@zte.com.cn>

'ac->ac_g_ex.fe_len' is a user-controlled value which is used in the
derivation of 'ac->ac_2order'. 'ac->ac_2order', in turn, is used to
index arrays which makes it a potential spectre gadget. Fix this by
sanitizing the value assigned to 'ac->ac2_order'.  This covers the
following accesses found with the help of smatch:

* fs/ext4/mballoc.c:1896 ext4_mb_simple_scan_group() warn: potential
  spectre issue 'grp->bb_counters' [w] (local cap)

* fs/ext4/mballoc.c:445 mb_find_buddy() warn: potential spectre issue
  'EXT4_SB(e4b->bd_sb)->s_mb_offsets' [r] (local cap)

* fs/ext4/mballoc.c:446 mb_find_buddy() warn: potential spectre issue
  'EXT4_SB(e4b->bd_sb)->s_mb_maxs' [r] (local cap)
Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Jeremy Cline <jcline@redhat.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@vger.kernel.org

Extended attribute names are defined to be NUL-terminated, so the name
must not contain a NUL character.  This is important because there are
places when remove extended attribute, the code uses strlen to
determine the length of the entry.  That should probably be fixed at
some point, but code is currently really messy, so the simplest fix
for now is to simply validate that the extended attributes are sane.

https://bugzilla.kernel.org/show_bug.cgi?id=200401Reported-by: Wen Xu <wen.xu@gatech.edu>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@vger.kernel.org

Out of memory should not be considered as critical errors; so replace
ext4_error() with ext4_warnig().
Signed-off-by: Wang Shilong <wshilong@ddn.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@vger.kernel.org

Whenever we hit block or inode bitmap corruptions we set
bit and then reduce this block group free inode/clusters
counter to expose right available space.

However some of ext4_mark_group_bitmap_corrupted() is called
inside group spinlock, some are not, this could make it happen
that we double reduce one block group free counters from system.

Always hold group spinlock for it could fix it, but it looks
a little heavy, we could use test_and_set_bit() to fix race
problems here.
Signed-off-by: Wang Shilong <wshilong@ddn.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@vger.kernel.org

When ext4_find_entry() falls back to "searching the old fashioned
way" due to a corrupt dx dir, it needs to reset the error code
to NULL so that the nonstandard ERR_BAD_DX_DIR code isn't returned
to userspace.

https://bugzilla.kernel.org/show_bug.cgi?id=199947Reported-by: Anatoly Trosinenko <anatoly.trosinenko@yandex.com>
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@vger.kernel.org

Follow the lead of xfs_break_dax_layouts() and add synchronization between
operations in ext4 which remove blocks from an inode (hole punch, truncate
down, etc.) and pages which are pinned due to DAX DMA operations.
Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Lukas Czerner <lczerner@redhat.com>

Inodes using DAX should only ever have exceptional entries in their page
caches.  Make this clear by warning if the iteration in
dax_layout_busy_page() ever sees a non-exceptional entry, and by adding a
comment for the pagevec_release() call which only deals with struct page
pointers.
Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Jan Kara <jack@suse.cz>

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

The superblock timestamp fields were enlarged by u8 to be 40 bits wide.
Update the documentation to reflect this.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

Create a new top-level section for documentation of filesystem usage,
on-disk format information, and anything else.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

Make use of the swap macro and remove unnecessary variable *tmp*.
This makes the code easier to read and maintain.

This code was detected with the help of Coccinelle.
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

There is no check for allocation failure when duplicating
"data" in ext4_remount(). Check for failure and return
error -ENOMEM in this case.
Signed-off-by: Chengguang Xu <cgxu519@gmx.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Andreas Dilger <adilger@dilger.ca>

Output the warning message before we clobber type and be -1 all the time.
The error message would now be

[    1.519791] EXT4-fs warning (device vdb): ext4_enable_quotas:5402:
Failed to enable quota tracking (type=0, err=-3). Please run e2fsck to fix.
Signed-off-by: Junichi Uekawa <uekawa@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Andreas Dilger <adilger@dilger.ca>

The inode timestamps use 34 bits in ext4, but the various timestamps in
the superblock are limited to 32 bits. If every user accesses these as
'unsigned', then this is good until year 2106, but it seems better to
extend this a bit further in the process of removing the deprecated
get_seconds() function.

This adds another byte for each timestamp in the superblock, making
them long enough to store timestamps beyond what is in the inodes,
which seems good enough here (in ocfs2, they are already 64-bit wide,
which is appropriate for a new layout).

I did not modify e2fsprogs, which obviously needs the same change to
actually interpret future timestamps correctly.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

jbd2 is one of the few callers of current_kernel_time64(), which
is a wrapper around ktime_get_coarse_real_ts64(). This calls the
latter directly for consistency with the rest of the kernel that
is moving to the ktime_get_ family of time accessors.
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

This is the last missing piece for the inode times on 32-bit systems:
now that VFS interfaces use timespec64, we just need to stop truncating
the tv_sec values for y2038 compatibililty.
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

We only care about the low 32-bit for i_dtime as explained in commit
b5f51573 ("ext4: avoid Y2038 overflow in recently_deleted()"), so
the use of get_seconds() is correct here, but that function is getting
removed in the process of the y2038 fixes, so let's use the modern
ktime_get_real_seconds() here.
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

The mmp_time field is 64 bits wide, which is good, but calling
get_seconds() results in a 32-bit value on 32-bit architectures. Using
ktime_get_real_seconds() instead returns 64 bits everywhere.
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

While working on extended rand for last_error/first_error timestamps,
I noticed that the endianess is wrong; we access the little-endian
fields in struct ext4_super_block as native-endian when we print them.

This adds a special case in ext4_attr_show() and ext4_attr_store()
to byteswap the superblock fields if needed.

In older kernels, this code was part of super.c, it got moved to
sysfs.c in linux-4.4.

Cc: stable@vger.kernel.org
Fixes: 52c198c6 ("ext4: add sysfs entry showing whether the fs contains errors")
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

Import the chapter about extended attributes from the on-disk format wiki
page into the kernel documentation.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

Import the chapter about directory layout from the on-disk format wiki
page into the kernel documentation.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

Import the chapter about inode data fork from the on-disk format wiki
page into the kernel documentation.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

Import the chapter about inodes from the on-disk format wiki
page into the kernel documentation.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

Import the chapter about the journal from the on-disk format wiki
page into the kernel documentation.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

Import the chapter about multi-mount protection from the on-disk format
wiki page into the kernel documentation.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

Import the chapter about bitmaps from the on-disk format wiki
page into the kernel documentation.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

Import the chapter about group descriptors from the on-disk format wiki
page into the kernel documentation.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

Import the chapter about superblocks from the on-disk format wiki
page into the kernel documentation.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

Import the chapter about high level design from the on-disk format wiki
page into the kernel documentation.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

Create the basic structure of the "new" data structures & algorithms
book to be ported over from the on-disk format wiki, and then start by
pulling in the introductory information.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

Convert the existing ext4 documentation into rst format and link it in
with the rest of the kernel documentation.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

Move Documentation/filesystems/ext4.txt into
Documentation/filesystems/ext4/ext4.rst in preparation for adding more
ext4 documentation.

Note that the documentation isn't in rst format yet, but as it's not
linked from anywhere it won't cause build errors.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

Commit 8844618d: "ext4: only look at the bg_flags field if it is
valid" will complain if block group zero does not have the
EXT4_BG_INODE_ZEROED flag set.  Unfortunately, this is not correct,
since a freshly created file system has this flag cleared.  It gets
almost immediately after the file system is mounted read-write --- but
the following somewhat unlikely sequence will end up triggering a
false positive report of a corrupted file system:

   mkfs.ext4 /dev/vdc
   mount -o ro /dev/vdc /vdc
   mount -o remount,rw /dev/vdc

Instead, when initializing the inode table for block group zero, test
to make sure that itable_unused count is not too large, since that is
the case that will result in some or all of the reserved inodes
getting cleared.

This fixes the failures reported by Eric Whiteney when running
generic/230 and generic/231 in the the nojournal test case.

Fixes: 8844618d ("ext4: only look at the bg_flags field if it is valid")
Reported-by: Eric Whitney <enwlinux@gmail.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

With commit 044e6e3d: "ext4: don't update checksum of new
initialized bitmaps" the buffer valid bit will get set without
actually setting up the checksum for the allocation bitmap, since the
checksum will get calculated once we actually allocate an inode or
block.

If we are doing this, then we need to (re-)check the verified bit
after we take the block group lock.  Otherwise, we could race with
another process reading and verifying the bitmap, which would then
complain about the checksum being invalid.

https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1780137Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org

The inline data code was updating the raw inode directly; this is
problematic since if metadata checksums are enabled,
ext4_mark_inode_dirty() must be called to update the inode's checksum.
In addition, the jbd2 layer requires that get_write_access() be called
before the metadata buffer is modified.  Fix both of these problems.

https://bugzilla.kernel.org/show_bug.cgi?id=200443Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@vger.kernel.org

Previously, when an MMP-protected file system is remounted read-only,
the kmmpd thread would exit the next time it woke up (a few seconds
later), without resetting the MMP sequence number back to
EXT4_MMP_SEQ_CLEAN.

Fix this by explicitly killing the MMP thread when the file system is
remounted read-only.
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: Andreas Dilger <adilger@dilger.ca>