nilfs2: use div64_ul() instead of do_div()

Fixes Coccinelle/coccicheck warnings reported by do_div.cocci.

Compared to do_div(), div64_ul() does not implicitly cast the divisor and
does not unnecessarily calculate the remainder.

Link: https://lkml.kernel.org/r/20240229210456.63234-2-thorsten.blum@toblux.com
Link: https://lkml.kernel.org/r/20240306142547.4612-1-konishi.ryusuke@gmail.com
Signed-off-by: Thorsten Blum <thorsten.blum@toblux.com>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

nilfs2: convert DAT to use kmap_local

Concerning the code of the metadata file DAT for disk address translation,
convert all parts that use the deprecated kmap_atomic to use kmap_local.
All transformations are directly possible.

Link: https://lkml.kernel.org/r/20240122140202.6950-8-konishi.ryusuke@gmail.com
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

nilfs2: prevent WARNING in nilfs_dat_commit_end()

If nilfs2 reads a corrupted disk image and its DAT metadata file contains
invalid lifetime data for a virtual block number, a kernel warning can be
generated by the WARN_ON check in nilfs_dat_commit_end() and can panic if
the kernel is booted with panic_on_warn.

This patch avoids the issue with a sanity check that treats it as an
error.

Since error return is not allowed in the execution phase of
nilfs_dat_commit_end(), this inserts that sanity check in
nilfs_dat_prepare_end(), which prepares for nilfs_dat_commit_end().

As the error code, -EINVAL is returned to notify bmap layer of the
metadata corruption. When the bmap layer sees this code, it handles the
abnormal situation and replaces the return code with -EIO as it should.

Link: https://lkml.kernel.org/r/000000000000154d2c05e9ec7df6@google.com
Link: https://lkml.kernel.org/r/20230127132202.6083-1-konishi.ryusuke@gmail.com
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Reported-by: <syzbot+cbff7a52b6f99059e67f@syzkaller.appspotmail.com>
Tested-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

nilfs2: replace WARN_ONs for invalid DAT metadata block requests

If DAT metadata file block access fails due to corruption of the DAT file
or abnormal virtual block numbers held by b-trees or inodes, a kernel
warning is generated.

This replaces the WARN_ONs by error output, so that a kernel, booted with
panic_on_warn, does not panic. This patch also replaces the detected
return code -ENOENT with another internal code -EINVAL to notify the bmap
layer of metadata corruption. When the bmap layer sees -EINVAL, it
handles the abnormal situation with nilfs_bmap_convert_error() and finally
returns code -EIO as it should.

Link: https://lkml.kernel.org/r/0000000000005cc3d205ea23ddcf@google.com
Link: https://lkml.kernel.org/r/20230126164114.6911-1-konishi.ryusuke@gmail.com
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Reported-by: <syzbot+5d5d25f90f195a3cfcb4@syzkaller.appspotmail.com>
Tested-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

nilfs2: fix NULL pointer dereference in nilfs_palloc_commit_free_entry()

Syzbot reported a null-ptr-deref bug:

NILFS (loop0): segctord starting. Construction interval = 5 seconds, CP
frequency < 30 seconds
general protection fault, probably for non-canonical address
0xdffffc0000000002: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017]
CPU: 1 PID: 3603 Comm: segctord Not tainted
6.1.0-rc2-syzkaller-00105-gb229b6ca5abb #0
Hardware name: Google Compute Engine/Google Compute Engine, BIOS Google
10/11/2022
RIP: 0010:nilfs_palloc_commit_free_entry+0xe5/0x6b0
fs/nilfs2/alloc.c:608
Code: 00 00 00 00 fc ff df 80 3c 02 00 0f 85 cd 05 00 00 48 b8 00 00 00
00 00 fc ff df 4c 8b 73 08 49 8d 7e 10 48 89 fa 48 c1 ea 03 <80> 3c 02
00 0f 85 26 05 00 00 49 8b 46 10 be a6 00 00 00 48 c7 c7
RSP: 0018:ffffc90003dff830 EFLAGS: 00010212
RAX: dffffc0000000000 RBX: ffff88802594e218 RCX: 000000000000000d
RDX: 0000000000000002 RSI: 0000000000002000 RDI: 0000000000000010
RBP: ffff888071880222 R08: 0000000000000005 R09: 000000000000003f
R10: 000000000000000d R11: 0000000000000000 R12: ffff888071880158
R13: ffff88802594e220 R14: 0000000000000000 R15: 0000000000000004
FS: 0000000000000000(0000) GS:ffff8880b9b00000(0000)
knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fb1c08316a8 CR3: 0000000018560000 CR4: 0000000000350ee0
Call Trace:
<TASK>
nilfs_dat_commit_free fs/nilfs2/dat.c:114 [inline]
nilfs_dat_commit_end+0x464/0x5f0 fs/nilfs2/dat.c:193
nilfs_dat_commit_update+0x26/0x40 fs/nilfs2/dat.c:236
nilfs_btree_commit_update_v+0x87/0x4a0 fs/nilfs2/btree.c:1940
nilfs_btree_commit_propagate_v fs/nilfs2/btree.c:2016 [inline]
nilfs_btree_propagate_v fs/nilfs2/btree.c:2046 [inline]
nilfs_btree_propagate+0xa00/0xd60 fs/nilfs2/btree.c:2088
nilfs_bmap_propagate+0x73/0x170 fs/nilfs2/bmap.c:337
nilfs_collect_file_data+0x45/0xd0 fs/nilfs2/segment.c:568
nilfs_segctor_apply_buffers+0x14a/0x470 fs/nilfs2/segment.c:1018
nilfs_segctor_scan_file+0x3f4/0x6f0 fs/nilfs2/segment.c:1067
nilfs_segctor_collect_blocks fs/nilfs2/segment.c:1197 [inline]
nilfs_segctor_collect fs/nilfs2/segment.c:1503 [inline]
nilfs_segctor_do_construct+0x12fc/0x6af0 fs/nilfs2/segment.c:2045
nilfs_segctor_construct+0x8e3/0xb30 fs/nilfs2/segment.c:2379
nilfs_segctor_thread_construct fs/nilfs2/segment.c:2487 [inline]
nilfs_segctor_thread+0x3c3/0xf30 fs/nilfs2/segment.c:2570
kthread+0x2e4/0x3a0 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306
</TASK>
...

If DAT metadata file is corrupted on disk, there is a case where
req->pr_desc_bh is NULL and blocknr is 0 at nilfs_dat_commit_end() during
a b-tree operation that cascadingly updates ancestor nodes of the b-tree,
because nilfs_dat_commit_alloc() for a lower level block can initialize
the blocknr on the same DAT entry between nilfs_dat_prepare_end() and
nilfs_dat_commit_end().

If this happens, nilfs_dat_commit_end() calls nilfs_dat_commit_free()
without valid buffer heads in req->pr_desc_bh and req->pr_bitmap_bh, and
causes the NULL pointer dereference above in
nilfs_palloc_commit_free_entry() function, which leads to a crash.

Fix this by adding a NULL check on req->pr_desc_bh and req->pr_bitmap_bh
before nilfs_palloc_commit_free_entry() in nilfs_dat_commit_free().

This also calls nilfs_error() in that case to notify that there is a fatal
flaw in the filesystem metadata and prevent further operations.

Link: https://lkml.kernel.org/r/00000000000097c20205ebaea3d6@google.com
Link: https://lkml.kernel.org/r/20221114040441.1649940-1-zhangpeng362@huawei.com
Link: https://lkml.kernel.org/r/20221119120542.17204-1-konishi.ryusuke@gmail.com
Signed-off-by: ZhangPeng <zhangpeng362@huawei.com>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Reported-by: syzbot+ebe05ee8e98f755f61d0@syzkaller.appspotmail.com
Tested-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

nilfs2: fix lockdep warnings during disk space reclamation

During disk space reclamation, nilfs2 still emits the following lockdep
warning due to page/folio operations on shadowed page caches that nilfs2
uses to get a snapshot of DAT file in memory:

WARNING: CPU: 0 PID: 2643 at include/linux/backing-dev.h:272 __folio_mark_dirty+0x645/0x670
...
RIP: 0010:__folio_mark_dirty+0x645/0x670
...
Call Trace:
filemap_dirty_folio+0x74/0xd0
__set_page_dirty_nobuffers+0x85/0xb0
nilfs_copy_dirty_pages+0x288/0x510 [nilfs2]
nilfs_mdt_save_to_shadow_map+0x50/0xe0 [nilfs2]
nilfs_clean_segments+0xee/0x5d0 [nilfs2]
nilfs_ioctl_clean_segments.isra.19+0xb08/0xf40 [nilfs2]
nilfs_ioctl+0xc52/0xfb0 [nilfs2]
__x64_sys_ioctl+0x11d/0x170

This fixes the remaining warning by using inode objects to hold those
page caches.

Link: https://lkml.kernel.org/r/1647867427-30498-3-git-send-email-konishi.ryusuke@gmail.com
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Tested-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Hao Sun <sunhao.th@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

nilfs2: remove filenames from file comments

Remove filenames that are not particularly useful in file comments, and
suppress checkpatch warnings

WARNING: It's generally not useful to have the filename in the file

Link: https://lkml.kernel.org/r/1635151862-11547-3-git-send-email-konishi.ryusuke@gmail.com
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Cc: Qing Wang <wangqing@vivo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

nilfs2: use a more common logging style

Add macros for nilfs_<level>(sb, fmt, ...) and convert the uses of
'nilfs_msg(sb, KERN_<LEVEL>, ...)' to 'nilfs_<level>(sb, ...)' so nilfs2
uses a logging style more like the typical kernel logging style.

Miscellanea:

o Realign arguments for these uses

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/1595860111-3920-4-git-send-email-konishi.ryusuke@gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

nilfs2: convert to SPDX license tags

Remove the verbose license text from NILFS2 files and replace them with
SPDX tags. This does not change the license of any of the code.

Link: http://lkml.kernel.org/r/1535624528-5982-1-git-send-email-konishi.ryusuke@lab.ntt.co.jp
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

nilfs2: reduce bare use of printk() with nilfs_msg()

Replace most use of printk() in nilfs2 implementation with nilfs_msg(),
and reduce the following checkpatch.pl warning:

"WARNING: Prefer [subsystem eg: netdev]_crit([subsystem]dev, ...
then dev_crit(dev, ... then pr_crit(... to printk(KERN_CRIT ..."

This patch also fixes a minor checkpatch warning "WARNING: quoted string
split across lines" that often accompanies the prior warning, and amends
message format as needed.

Link: http://lkml.kernel.org/r/1464875891-5443-5-git-send-email-konishi.ryusuke@lab.ntt.co.jp
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

nilfs2: avoid bare use of 'unsigned'

This fixes checkpatch.pl warning "WARNING: Prefer 'unsigned int' to
bare use of 'unsigned'".

Link: http://lkml.kernel.org/r/1462886671-3521-5-git-send-email-konishi.ryusuke@lab.ntt.co.jp
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

nilfs2: clean up old e-mail addresses

E-mail addresses of osrg.net domain are no longer available. This
removes them from authorship notices and prevents reporters from being
confused.

Link: http://lkml.kernel.org/r/1461935747-10380-5-git-send-email-konishi.ryusuke@lab.ntt.co.jp
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

nilfs2: remove FSF mailing address from GPL notices

This removes the extra paragraph which mentions FSF address in GPL
notices from source code of nilfs2 and avoids the checkpatch.pl error
related to it.

Link: http://lkml.kernel.org/r/1461935747-10380-4-git-send-email-konishi.ryusuke@lab.ntt.co.jp
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

nilfs2: fix gcc unused-but-set-variable warnings

Fix the following build warnings:

$ make W=1
[...]
CC [M] fs/nilfs2/btree.o
fs/nilfs2/btree.c: In function 'nilfs_btree_split':
fs/nilfs2/btree.c:923:8: warning: variable 'newptr' set but not used [-Wunused-but-set-variable]
__u64 newptr;
^
fs/nilfs2/btree.c:922:8: warning: variable 'newkey' set but not used [-Wunused-but-set-variable]
__u64 newkey;
^
CC [M] fs/nilfs2/dat.o
fs/nilfs2/dat.c: In function 'nilfs_dat_prepare_end':
fs/nilfs2/dat.c:158:8: warning: variable 'start' set but not used [-Wunused-but-set-variable]
__u64 start;
^
CC [M] fs/nilfs2/segment.o
fs/nilfs2/segment.c: In function 'nilfs_segctor_do_immediate_flush':
fs/nilfs2/segment.c:2433:6: warning: variable 'err' set but not used [-Wunused-but-set-variable]
int err;
^
CC [M] fs/nilfs2/sufile.o
fs/nilfs2/sufile.c: In function 'nilfs_sufile_alloc':
fs/nilfs2/sufile.c:320:27: warning: variable 'ncleansegs' set but not used [-Wunused-but-set-variable]
unsigned long nsegments, ncleansegs, nsus, cnt;
^
CC [M] fs/nilfs2/alloc.o
fs/nilfs2/alloc.c: In function 'nilfs_palloc_prepare_alloc_entry':
fs/nilfs2/alloc.c:478:38: warning: variable 'groups_per_desc_block' set but not used [-Wunused-but-set-variable]
unsigned long n, entries_per_group, groups_per_desc_block;
^

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

nilfs2: verify metadata sizes read from disk

Add code to check sizes of on-disk data of metadata files such as inode
size, segment usage size, DAT entry size, and checkpoint size. Although
these sizes are read from disk, the current implementation doesn't check
them.

If these sizes are not sane on disk, it can cause out-of-range access to
metadata or memory access overrun on metadata block buffers due to
overflow in sundry calculations.

Both lower limit and upper limit of metadata sizes are verified to
prevent these issues.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Cc: Andreas Rohner <andreas.rohner@gmx.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

nilfs2: add omitted comments for different structures in driver implementation

Add omitted comments for different structures in driver implementation.

Signed-off-by: Vyacheslav Dubeyko <slava@dubeyko.com>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

nilfs2: remove the second argument of k[un]map_atomic()

Acked-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Cong Wang <amwang@redhat.com>

nilfs2: use mark_buffer_dirty to mark btnode or meta data dirty

This replaces nilfs_mdt_mark_buffer_dirty and nilfs_btnode_mark_dirty
macros with mark_buffer_dirty and gets rid of nilfs_mark_buffer_dirty,
an own mark buffer dirty function.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

nilfs2: fix typo in comment of nilfs_dat_move function

Fixes a typo: "uncommited" -> "uncommitted".

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

nilfs2: eliminate sparse warnings - "symbol not declared"

change nilfs_dat_commit_free and nilfs_inode_cachep static
to fix following warnings

fs/nilfs2/super.c:72:19: warning: symbol 'nilfs_inode_cachep' was not declared. Should it be static?
fs/nilfs2/dat.c:106:6: warning: symbol 'nilfs_dat_commit_free' was not declared. Should it be static?

Signed-off-by: Jiro SEKIBA <jir@unicus.jp>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

nilfs2: use iget for all metadata files

This makes use of iget5_locked to allocate or get inode for metadata
files to stop using own inode allocator.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

nilfs2: get rid of GCDAT inode

This applies prepared rollback function and redirect function of
metadata file to DAT file, and eliminates GCDAT inode.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

nilfs2: fix various typos in comments

This fixes various typos I found in comments of nilfs2.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

nilfs2: delete unnecessary condition in nilfs_dat_translate

This is a trivial patch to delete unnecessary condition in nilfs_dat_translate.

nilfs_dat_translate() will asign translated address to *blocknrp if blocknrp
is not NULL. However the condition is unneeded, because all callers of
nilfs_dat_translate() pass blocknrp properly.

Signed-off-by: Jiro SEKIBA <jir@unicus.jp>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

nilfs2: add palloc cache to dat

This adds the palloc cache to DAT file. The palloc cache is allocated
on the extended region of nilfs_mdt_info struct. The struct
nilfs_dat_info defines the extended on memory structure of DAT.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

nilfs2: separate read method of meta data files on super root block

Will displace nilfs_mdt_read_inode_direct function with an individual
read method: nilfs_dat_read, nilfs_sufile_read, nilfs_cpfile_read.

This provides the opportunity to initialize local variables of each
metadata file after reading the inode.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

nilfs2: separate constructor of metadata files

This will displace nilfs_mdt_new() constructor with individual
metadata file constructors like nilfs_dat_new(), new_sufile_new(),
nilfs_cpfile_new(), and nilfs_ifile_new().

This makes it possible for each metadata file to have own
intialization code.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

nilfs2: add update functions of virtual block address to dat

This is a preparation for the successive cleanup ("nilfs2: allow btree
to directly call dat operations").

This adds functions bundling a few operations to change an entry of
virtual block address on the dat file.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

nilfs2: remove nilfs_dat_abort_start and nilfs_dat_abort_free

These functions are not called from any functions.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

nilfs2: fix incorrect KERN_CRIT messages in case of write failures

In case of write-failure retries, the following KERN_CRIT level
messages are mistakenly output by nilfs_dat_commit_start() function:

nilfs_dat_commit_start: vbn = 408463, start = 12506, end = 18446744073709551615, pbn = 530210
nilfs_dat_commit_start: vbn = 408515, start = 12506, end = 18446744073709551615, pbn = 530211
nilfs_dat_commit_start: vbn = 408464, start = 12506, end = 18446744073709551615, pbn = 530212
...

This suppresses these messages.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Cc: stable@kernel.org

nilfs2: allow future expansion of metadata read out via get info ioctl

Nilfs has some ioctl commands to read out metadata from meta data
files:

- NILFS_IOCTL_GET_CPINFO for checkpoint file,
- NILFS_IOCTL_GET_SUINFO for segment usage file, and
- NILFS_IOCTL_GET_VINFO for Disk Address Transalation (DAT) file,
respectively.

Every routine on these metadata files is implemented so that it allows
future expansion of on-disk format. But, the above ioctl commands do
not support expansion even though nilfs_argv structure can handle
arbitrary size for data exchanged via ioctl.

This allows future expansion of the following structures which give
basic format of the "get information" ioctls:

- struct nilfs_cpinfo
- struct nilfs_suinfo
- struct nilfs_vinfo

So, this introduces forward compatility of such ioctl commands.

In this patch, a sanity check in nilfs_ioctl_get_info() function is
changed to accept larger data structure [1], and metadata read
routines are rewritten so that they become compatible for larger
structures; the routines will just ignore the remaining fields which
the current version of nilfs doesn't know.

[1] The ioctl function already has another upper limit (PAGE_SIZE
against a structure, which appears in nilfs_ioctl_wrap_copy
function), and this will not cause security problem.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

nilfs2: remove nilfs_dat_prepare_free function

This function is unused.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

nilfs2: replace BUG_ON and BUG calls triggerable from ioctl

Pekka Enberg advised me:
> It would be nice if BUG(), BUG_ON(), and panic() calls would be
> converted to proper error handling using WARN_ON() calls. The BUG()
> call in nilfs_cpfile_delete_checkpoints(), for example, looks to be
> triggerable from user-space via the ioctl() system call.

This will follow the comment and keep them to a minimum.

Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

nilfs2: disk address translator

This adds the disk address translation file (DAT) whose primary function
is to convert virtual disk block numbers to actual disk block numbers.

The virtual block numbers of NILFS are associated with checkpoint
generation numbers, and this file also provides functions to manage the
lifetime information of each virtual block number.

Signed-off-by: Koji Sato <sato.koji@lab.ntt.co.jp>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>