When EXT2_ATTR_DEBUG is not defined, modify the 2 debug macros
to use the no_printk() macro instead of <nothing>.
This fixes gcc warnings when -Wextra is used:

../fs/ext2/xattr.c:252:42: warning: suggest braces around empty body in an ‘if’ statement [-Wempty-body]
../fs/ext2/xattr.c:258:42: warning: suggest braces around empty body in an ‘if’ statement [-Wempty-body]
../fs/ext2/xattr.c:330:42: warning: suggest braces around empty body in an ‘if’ statement [-Wempty-body]
../fs/ext2/xattr.c:872:45: warning: suggest braces around empty body in an ‘else’ statement [-Wempty-body]

I have verified that the only object code change (with gcc 7.5.0) is
the reversal of some instructions from 'cmp a,b' to 'cmp b,a'.

Link: https://lore.kernel.org/r/e18a7395-61fb-2093-18e8-ed4f8cf56248@infradead.org
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Jan Kara <jack@suse.com>
Cc: linux-ext4@vger.kernel.org
Signed-off-by: Jan Kara <jack@suse.cz>

Fix a debug-only build error in ext2/xattr.c:

When building without extra debugging, (and with another patch that uses
no_printk() instead of <empty> for the ext2-xattr debug-print macros,
this build error happens:

../fs/ext2/xattr.c: In function ‘ext2_xattr_cache_insert’:
../fs/ext2/xattr.c:869:18: error: ‘ext2_xattr_cache’ undeclared (first use in
this function); did you mean ‘ext2_xattr_list’?
     atomic_read(&ext2_xattr_cache->c_entry_count));

Fix the problem by removing cached entry count from the debug message
since otherwise we'd have to export the mbcache structure just for that.

Fixes: be0726d33cb8 ("ext2: convert to mbcache2")
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Jan Kara <jack@suse.cz>

The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:

struct foo {
        int stuff;
        struct boo array[];
};

By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.

Also, notice that, dynamic memory allocations won't be affected by
this change:

"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]

This issue was found with the help of Coccinelle.

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour")

Link: https://lore.kernel.org/r/20200309180441.GA2992@embeddedor
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Jan Kara <jack@suse.cz>

Lockdep complains about a chain:
  sb_internal#2 --> &ei->xattr_sem#2 --> fs_reclaim

and shrink_dentry_list -> ext2_evict_inode -> ext2_xattr_delete_inode ->
down_write(ei->xattr_sem) creating a locking cycle in the reclaim path.
This is however a false positive because when we are in
ext2_evict_inode() we are the only holder of the inode reference and
nobody else should touch xattr_sem of that inode. So we cannot ever
block on acquiring the xattr_sem in the reclaim path.

Silence the lockdep warning by using down_write_trylock() in
ext2_xattr_delete_inode() to not create false locking dependency.

Reported-by: "J. R. Okajima" <hooanon05g@gmail.com>
Reviewed-by: Ritesh Harjani <riteshh@linux.ibm.com>
Signed-off-by: Jan Kara <jack@suse.cz>

Pull dax fixes from Dan Williams:
 "A fix for an xfstest failure and some and an update that removes an
  fsdax dependency on block devices.

  Summary:

   - Fix RWF_NOWAIT writes to properly return -EAGAIN

   - Clean up an unused helper

   - Update dax_writeback_mapping_range to not need a block_device
     argument"

* tag 'dax-fixes-5.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm:
  dax: pass NOWAIT flag to iomap_apply
  dax: Get rid of fs_dax_get_by_host() helper
  dax: Pass dax_dev instead of bdev to dax_writeback_mapping_range()

Clang warns:

../fs/ext2/super.c:1076:3: warning: misleading indentation; statement is
not part of the previous 'if' [-Wmisleading-indentation]
        sbi->s_groups_count = ((le32_to_cpu(es->s_blocks_count) -
        ^
../fs/ext2/super.c:1074:2: note: previous statement is here
        if (EXT2_BLOCKS_PER_GROUP(sb) == 0)
        ^
1 warning generated.

This warning occurs because there is a space before the tab on this
line. Remove it so that the indentation is consistent with the Linux
kernel coding style and clang no longer warns.

Fixes: 41f04d852e35 ("[PATCH] ext2: fix mounts at 16T")
Link: https://github.com/ClangBuiltLinux/linux/issues/827
Link: https://lore.kernel.org/r/20191218031930.31393-1-natechancellor@gmail.com
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

As of now dax_writeback_mapping_range() takes "struct block_device" as a
parameter and dax_dev is searched from bdev name. This also involves taking
a fresh reference on dax_dev and putting that reference at the end of
function.

We are developing a new filesystem virtio-fs and using dax to access host
page cache directly. But there is no block device. IOW, we want to make
use of dax but want to get rid of this assumption that there is always
a block device associated with dax_dev.

So pass in "struct dax_device" as parameter instead of bdev.

ext2/ext4/xfs are current users and they already have a reference on
dax_device. So there is no need to take reference and drop reference to
dax_device on each call of this function.

Suggested-by: Christoph Hellwig <hch@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Link: https://lore.kernel.org/r/20200103183307.GB13350@redhat.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

Set proper errno in the case of failure of
initializing percpu variables.

Link: https://lore.kernel.org/r/20191129013636.7624-1-cgxu519@mykernel.net
Signed-off-by: Chengguang Xu <cgxu519@mykernel.net>
Signed-off-by: Jan Kara <jack@suse.cz>

Pull ext2, quota, reiserfs cleanups and fixes from Jan Kara:

 - Refactor the quota on/off kernel internal interfaces (mostly for
   ubifs quota support as ubifs does not want to have inodes holding
   quota information)

 - A few other small quota fixes and cleanups

 - Various small ext2 fixes and cleanups

 - Reiserfs xattr fix and one cleanup

* tag 'for_v5.5-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs: (28 commits)
  ext2: code cleanup for descriptor_loc()
  fs/quota: handle overflows of sysctl fs.quota.* and report as unsigned long
  ext2: fix improper function comment
  ext2: code cleanup for ext2_try_to_allocate()
  ext2: skip unnecessary operations in ext2_try_to_allocate()
  ext2: Simplify initialization in ext2_try_to_allocate()
  ext2: code cleanup by calling ext2_group_last_block_no()
  ext2: introduce new helper ext2_group_last_block_no()
  reiserfs: replace open-coded atomic_dec_and_mutex_lock()
  ext2: check err when partial != NULL
  quota: Handle quotas without quota inodes in dquot_get_state()
  quota: Make dquot_disable() work without quota inodes
  quota: Drop dquot_enable()
  fs: Use dquot_load_quota_inode() from filesystems
  quota: Rename vfs_load_quota_inode() to dquot_load_quota_inode()
  quota: Simplify dquot_resume()
  quota: Factor out setup of quota inode
  quota: Check that quota is not dirty before release
  quota: fix livelock in dquot_writeback_dquots
  ext2: don't set *count in the case of failure in ext2_try_to_allocate()
  ...

Code cleanup by removing unnecessary variable
in descriptor_loc().

Link: https://lore.kernel.org/r/20191115224900.2613-1-cgxu519@mykernel.net
Signed-off-by: Chengguang Xu <cgxu519@mykernel.net>
Signed-off-by: Jan Kara <jack@suse.cz>