This patch basically reverts the majority of patch 5407e242.
That patch eliminated the gfs2_qadata structure in favor of just
using the reservations structure. The problem with doing that is that
it increases the size of the reservations structure. That is not an
issue until it comes time to fold the reservations structure into the
inode in memory so we know it's always there. By separating out the
quota structure again, we aren't punishing the non-quota users by
making all the inodes bigger, requiring more slab space. This patch
creates a new slab area to allocate the quota stuff so it's managed
a little more sanely.
Signed-off-by: NBob Peterson <rpeterso@redhat.com>

Instead of submitting a READ_SYNC bio for the inode and a READA bio for
the inode's extended attributes through submit_bh, submit a single READ_SYNC
bio for both through submit_bio when possible.  This can be more
efficient on some kinds of block devices.
Signed-off-by: NAndreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: NBob Peterson <rpeterso@redhat.com>

When gfs2 allocates an inode and its extended attribute block next to
each other at inode create time, the inode's directory entry indicates
that in de_rahead.  In that case, we can readahead the extended
attribute block when we read in the inode.
Signed-off-by: NAndreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: NBob Peterson <rpeterso@redhat.com>

This lockdep splat was being triggered on umount:

[55715.973122] ===============================
[55715.980169] [ INFO: suspicious RCU usage. ]
[55715.981021] 4.3.0-11553-g8d3de01c-dirty #15 Tainted: G        W
[55715.982353] -------------------------------
[55715.983301] fs/gfs2/glock.c:1427 suspicious rcu_dereference_protected() usage!

The code it refers to is the rht_for_each_entry_safe usage in
glock_hash_walk. The condition that triggers the warning is
lockdep_rht_bucket_is_held(tbl, hash) which is checked in the
__rcu_dereference_protected macro.

The rhashtable buckets are not changed in glock_hash_walk so it's safe
to rely on the rcu protection. Replace the rht_for_each_entry_safe()
usage with rht_for_each_entry_rcu(), which doesn't care whether the
bucket lock is held if the rcu read lock is held.
Signed-off-by: NAndrew Price <anprice@redhat.com>
Signed-off-by: NBob Peterson <rpeterso@redhat.com>
Acked-by: NSteven Whitehouse <swhiteho@redhat.com>

The iput() function tests whether its argument is NULL and then
returns immediately. Thus the test around the call is not needed.

This issue was detected by using the Coccinelle software.
Signed-off-by: NMarkus Elfring <elfring@users.sourceforge.net>
Signed-off-by: NBob Peterson <rpeterso@redhat.com>

When new files and directories are created inside a parent directory
we automatically inherit the GFS2_DIF_SYSTEM flag (if set) and assign
it to the new file/dirs.

All new system files/dirs created in the metafs by, say gfs2_jadd,
will have this flag set because they will have parent directories in
the metafs whose GFS2_DIF_SYSTEM flag has already been set (most likely
by a previous mkfs.gfs2)
Signed-off-by: NAbhi Das <adas@redhat.com>
Signed-off-by: NBob Peterson <rpeterso@redhat.com>

The ELF binary loader in binfmt_elf.c requires an MMU, making it
impossible to use regular ELF binaries on NOMMU archs.  However, the FDPIC
ELF loader in binfmt_elf_fdpic.c is fully capable as a loader for plain
ELF, which requires constant displacements between LOAD segments, since it
already supports FDPIC ELF files flagged as needing constant displacement.

This patch adjusts the FDPIC ELF loader to accept non-FDPIC ELF files on
NOMMU archs.  They are treated identically to FDPIC ELF files with the
constant-displacement flag bit set, except for personality, which must
match the ABI of the program being loaded; the PER_LINUX_FDPIC personality
controls how the kernel interprets function pointers passed to sigaction.

Files that do not set a stack size requirement explicitly are given a
default stack size (matching the amount of committed stack the normal ELF
loader for MMU archs would give them) rather than being rejected; this is
necessary because plain ELF files generally do not declare stack
requirements in theit program headers.

Only ET_DYN (PIE) format ELF files are supported, since loading at a fixed
virtual address is not possible on NOMMU.

This patch was developed and tested on J2 (SH2-compatible) but should
be usable immediately on all archs where binfmt_elf_fdpic is
available. Moreover, by providing dummy definitions of the
elf_check_fdpic() and elf_check_const_displacement() macros for archs
which lack an FDPIC ABI, it should be possible to enable building of
binfmt_elf_fdpic on all other NOMMU archs and thereby give them ELF
binary support, but I have not yet tested this.

The motivation for using binfmt_elf_fdpic.c rather than adapting
binfmt_elf.c to NOMMU is that the former already has all the necessary
code to work properly on NOMMU and has already received widespread
real-world use and testing. I hope this is not controversial.

I'm not really happy with having to unset the FDPIC_FUNCPTRS
personality bit when loading non-FDPIC ELF. This bit should really
reset automatically on execve, since otherwise, executing non-ELF
binaries (e.g. bFLT) from an FDPIC process will leave the personality
in the wrong state and severely break signal handling. But that's a
separate, existing bug and I don't know the right place to fix it.
Signed-off-by: NRich Felker <dalias@libc.org>
Acked-by: NGreg Ungerer <gerg@uclinux.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Matt Mackall <mpm@selenic.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: David Howells <dhowells@redhat.com>
Cc: Oleg Endo <oleg.endo@t-online.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

new_valid_dev() always returns 1, so the !new_valid_dev() check is not
needed.  Remove it.
Signed-off-by: NYaowei Bai <bywxiaobai@163.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

new_valid_dev() always returns 1, so the !new_valid_dev() check is not
needed.  Remove it.
Signed-off-by: NYaowei Bai <bywxiaobai@163.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

new_valid_dev() always returns 1, so the !new_valid_dev() check is not
needed.  Remove it.
Signed-off-by: NYaowei Bai <bywxiaobai@163.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Acked-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

new_valid_dev() always returns 1, so the !new_valid_dev() check is not
needed.  Remove it.
Signed-off-by: NYaowei Bai <bywxiaobai@163.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Petr Vandrovec <petr@vandrovec.name>
Cc: Jan Kara <jack@suse.cz>
Cc: Jens Axboe <axboe@fb.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Fabian Frederick <fabf@skynet.be>
Cc: David Howells <dhowells@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

new_valid_dev() always returns 1, so the !new_valid_dev() checks are not
needed.  Remove them.
Signed-off-by: NYaowei Bai <bywxiaobai@163.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Acked-by: NDave Kleikamp <dave.kleikamp@oracle.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

new_valid_dev() always returns 1, so the !new_valid_dev() check is not
needed.  Remove it.
Signed-off-by: NYaowei Bai <bywxiaobai@163.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Mikulas Patocka <mikulas@artax.karlin.mff.cuni.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

new_valid_dev() always returns 1, so the !new_valid_dev() check is not
needed.  Remove it.
Signed-off-by: NYaowei Bai <bywxiaobai@163.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Jaegeuk Kim <jaegeuk@kernel.org>
Cc: Changman Lee <cm224.lee@samsung.com>
Cc: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

new_valid_dev() always returns 1, so the !new_valid_dev() check is not
needed.  Remove it.
Signed-off-by: NYaowei Bai <bywxiaobai@163.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Jan Kara <jack@suse.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

new_valid_dev() always returns 1, so the !new_valid_dev() check is not
needed.  Remove it.
Signed-off-by: NYaowei Bai <bywxiaobai@163.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Acked-by: NBoaz Harrosh <ooo@electrozaur.com>
Cc: Benny Halevy <bhalevy@primarydata.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

new_valid_dev() always returns 1, so the !new_valid_dev() check is not
needed.  Remove it.
Signed-off-by: NYaowei Bai <bywxiaobai@163.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Chris Mason <clm@fb.com>
Cc: Josef Bacik <jbacik@fb.com>
Acked-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

new_valid_dev() always returns 1, so the !new_valid_dev() check is not
needed.  Remove it.
Signed-off-by: NYaowei Bai <bywxiaobai@163.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Eric Van Hensbergen <ericvh@gmail.com>
Cc: Ron Minnich <rminnich@sandia.gov>
Cc: Latchesar Ionkov <lucho@ionkov.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Switch everything to the new and more capable implementation of abs().
Mainly to give the new abs() a bit of a workout.

Cc: Michal Nazarewicz <mina86@mina86.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Fix kernel-doc warnings in fs/fs-writeback.c by moving a #define macro to
after the function's opening brace.  Also #undef this macro at the end of
the function.

  ../fs/fs-writeback.c:1984: warning: Excess function parameter 'inode' description in 'I_DIRTY_INODE'
  ../fs/fs-writeback.c:1984: warning: Excess function parameter 'flags' description in 'I_DIRTY_INODE'
Signed-off-by: NRandy Dunlap <rdunlap@infradead.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Fix kernel-doc warning in fs/inode.c:

  ../fs/inode.c:1606: warning: No description found for parameter 'inode'
Signed-off-by: NRandy Dunlap <rdunlap@infradead.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This patch fixes a bug introduced by commit 7005c3e4. That patch
tries to map a vm range for resource groups, but the calculation
breaks down when the block size is less than the page size.
Signed-off-by: NBob Peterson <rpeterso@redhat.com>

Since 5cec38ac ("fs, seq_file: fallback to vmalloc instead of oom kill
processes") seq_buf_alloc() avoids calling the oom killer for PAGE_SIZE or
smaller allocations; but larger allocations can use the oom killer via
vmalloc().  Thus reads of small files can return ENOMEM, but larger files
use the oom killer to avoid ENOMEM.

The effect of this bug is that reads from /proc and other virtual
filesystems can return ENOMEM instead of the preferred behavior - oom
killing something (possibly the calling process).  I don't know of anyone
except Google who has noticed the issue.

I suspect the fix is more needed in smaller systems where there isn't any
reclaimable memory.  But these seem like the kinds of systems which
probably don't use the oom killer for production situations.

Memory overcommit requires use of the oom killer to select a victim
regardless of file size.

Enable oom killer for small seq_buf_alloc() allocations.

Fixes: 5cec38ac ("fs, seq_file: fallback to vmalloc instead of oom kill processes")
Signed-off-by: NDavid Rientjes <rientjes@google.com>
Signed-off-by: NGreg Thelen <gthelen@google.com>
Acked-by: NEric Dumazet <edumazet@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

strint_escape_str() escapes input string by given criteria.  In case of
seq_escape() the criteria is to convert some characters to their octal
representation.
Signed-off-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This improves code readability.
Signed-off-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Change zap_threads() paths to use for_each_thread() rather than
while_each_thread().

While at it, change zap_threads() to avoid the nested if's to make the
code more readable and lessen the indentation.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Kyle Walker <kwalker@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Stanislav Kozina <skozina@redhat.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

task_will_free_mem() is wrong in many ways, and in particular the
SIGNAL_GROUP_COREDUMP check is not reliable: a task can participate in the
coredumping without SIGNAL_GROUP_COREDUMP bit set.

change zap_threads() paths to always set SIGNAL_GROUP_COREDUMP even if
other CLONE_VM processes can't react to SIGKILL.  Fortunately, at least
oom-kill case if fine; it kills all tasks sharing the same mm, so it
should also kill the process which actually dumps the core.

The change in prepare_signal() is not strictly necessary, it just ensures
that the patch does not bring another subtle behavioural change.  But it
reminds us that this SIGNAL_GROUP_EXIT/COREDUMP case needs more changes.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Kyle Walker <kwalker@redhat.com>
Acked-by: NMichal Hocko <mhocko@suse.com>
Cc: Stanislav Kozina <skozina@redhat.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

jffs2_garbage_collect_thread() does allow_signal(SIGCONT) for no reason,
SIGCONT will wake a stopped task up even if it is ignored.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Reviewed-by: NTejun Heo <tj@kernel.org>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Felipe Balbi <balbi@ti.com>
Cc: Markus Pargmann <mpa@pengutronix.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

jffs2_garbage_collect_thread() can race with SIGCONT and sleep in
TASK_STOPPED state after it was already sent. Add the new helper,
kernel_signal_stop(), which does this correctly.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Reviewed-by: NTejun Heo <tj@kernel.org>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Felipe Balbi <balbi@ti.com>
Cc: Markus Pargmann <mpa@pengutronix.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

1. Rename dequeue_signal_lock() to kernel_dequeue_signal(). This
   matches another "for kthreads only" kernel_sigaction() helper.

2. Remove the "tsk" and "mask" arguments, they are always current
   and current->blocked. And it is simply wrong if tsk != current.

3. We could also remove the 3rd "siginfo_t *info" arg but it looks
   potentially useful. However we can simplify the callers if we
   change kernel_dequeue_signal() to accept info => NULL.

4. Remove _irqsave, it is never called from atomic context.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Reviewed-by: NTejun Heo <tj@kernel.org>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Felipe Balbi <balbi@ti.com>
Cc: Markus Pargmann <mpa@pengutronix.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Some false positive warnings are reported for powerpc build.

The following warnings are reported in
 http://kisskb.ellerman.id.au/kisskb/buildresult/12519703/

   CC      fs/nilfs2/super.o
 fs/nilfs2/super.c: In function 'nilfs_resize_fs':
 fs/nilfs2/super.c:376:2: warning: 'blocknr' may be used uninitialized in this function [-Wuninitialized]
 fs/nilfs2/super.c:362:11: note: 'blocknr' was declared here
   CC      fs/nilfs2/recovery.o
 fs/nilfs2/recovery.c: In function 'nilfs_salvage_orphan_logs':
 fs/nilfs2/recovery.c:631:21: warning: 'sum' may be used uninitialized in this function [-Wuninitialized]
 fs/nilfs2/recovery.c:585:32: note: 'sum' was declared here
 fs/nilfs2/recovery.c: In function 'nilfs_search_super_root':
 fs/nilfs2/recovery.c:873:11: warning: 'sum' may be used uninitialized in this function [-Wuninitialized]

Another similar warning is reported in
 http://kisskb.ellerman.id.au/kisskb/buildresult/12520079/

   CC      fs/nilfs2/btree.o
 fs/nilfs2/btree.c: In function 'nilfs_btree_convert_and_insert':
 include/asm-generic/bitops/non-atomic.h:105:20: warning: 'bh' may be used uninitialized in this function [-Wuninitialized]
 fs/nilfs2/btree.c:1859:22: note: 'bh' was declared here

This cleans out these warnings by forcing the variables to be initialized.
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Reported-by: NGeert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

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: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This patch adds tracepoints for analyzing requests of reading and writing
metadata files.  The tracepoints cover every in-place mdt files (cpfile,
sufile, and datfile).

Example of tracing mdt_insert_new_block():
              cp-14635 [000] ...1 30598.199309: nilfs2_mdt_insert_new_block: inode = ffff88022a8d0178 ino = 3 block = 155
              cp-14635 [000] ...1 30598.199520: nilfs2_mdt_insert_new_block: inode = ffff88022a8d0178 ino = 3 block = 5
              cp-14635 [000] ...1 30598.200828: nilfs2_mdt_insert_new_block: inode = ffff88022a8d0178 ino = 3 block = 253
Signed-off-by: NHitoshi Mitake <mitake.hitoshi@lab.ntt.co.jp>
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: TK Kato <TK.Kato@wdc.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This patch adds tracepoints which would be useful for analyzing segment
usage from a perspective of high level sufile manipulation (check, alloc,
free).  sufile is an important in-place updated metadata file, so
analyzing the behavior would be useful for performance turning.

example of usage (a case of allocation):

$ sudo bin/tpoint nilfs2:nilfs2_segment_usage_allocated
Tracing nilfs2:nilfs2_segment_usage_allocated. Ctrl-C to end.
        segctord-17800 [002] ...1 10671.867294: nilfs2_segment_usage_allocated: sufile = ffff880054f908a8 segnum = 2
        segctord-17800 [002] ...1 10675.073477: nilfs2_segment_usage_allocated: sufile = ffff880054f908a8 segnum = 3
Signed-off-by: NHitoshi Mitake <mitake.hitoshi@lab.ntt.co.jp>
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Benixon Dhas <benixon.dhas@wdc.com>
Cc: TK Kato <TK.Kato@wdc.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This patch adds a tracepoint for transaction events of nilfs.  With the
tracepoint, these events can be tracked: begin, abort, commit, trylock,
lock, and unlock.  Basically, these events have corresponding functions
e.g.  begin event corresponds nilfs_transaction_begin().  The unlock event
is an exception.  It corresponds to the iteration in
nilfs_transaction_lock().

Only one tracepoint is introcued: nilfs2_transaction_transition.  The
above events are distinguished with newly introduced enum.  With this
tracepoint, we can analyse a critical section of segment constructoin.

Sample output by tpoint of perf-tools:
              cp-4457  [000] ...1    63.266220: nilfs2_transaction_transition: sb = ffff8802112b8800 ti = ffff8800bf5ccc58 count = 1 flags = 9 state = BEGIN
              cp-4457  [000] ...1    63.266221: nilfs2_transaction_transition: sb = ffff8802112b8800 ti = ffff8800bf5ccc58 count = 0 flags = 9 state = COMMIT
              cp-4457  [000] ...1    63.266221: nilfs2_transaction_transition: sb = ffff8802112b8800 ti = ffff8800bf5ccc58 count = 0 flags = 9 state = COMMIT
        segctord-4371  [001] ...1    68.261196: nilfs2_transaction_transition: sb = ffff8802112b8800 ti = ffff8800b889bdf8 count = 0 flags = 10 state = TRYLOCK
        segctord-4371  [001] ...1    68.261280: nilfs2_transaction_transition: sb = ffff8802112b8800 ti = ffff8800b889bdf8 count = 0 flags = 10 state = LOCK
        segctord-4371  [001] ...1    68.261877: nilfs2_transaction_transition: sb = ffff8802112b8800 ti = ffff8800b889bdf8 count = 1 flags = 10 state = BEGIN
        segctord-4371  [001] ...1    68.262116: nilfs2_transaction_transition: sb = ffff8802112b8800 ti = ffff8800b889bdf8 count = 0 flags = 18 state = COMMIT
        segctord-4371  [001] ...1    68.265032: nilfs2_transaction_transition: sb = ffff8802112b8800 ti = ffff8800b889bdf8 count = 0 flags = 18 state = UNLOCK
        segctord-4371  [001] ...1   132.376847: nilfs2_transaction_transition: sb = ffff8802112b8800 ti = ffff8800b889bdf8 count = 0 flags = 10 state = TRYLOCK

This patch also does trivial cleaning of comma usage in collection stage
transition event for consistent coding style.
Signed-off-by: NHitoshi Mitake <mitake.hitoshi@lab.ntt.co.jp>
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This patch adds a tracepoint for tracking stage transition of block
collection in segment construction.  With the tracepoint, we can analysis
the behavior of segment construction in depth.  It would be useful for
bottleneck detection and debugging, etc.

The tracepoint is created with the standard trace API of linux (like ext3,
ext4, f2fs and btrfs).  So we can analysis with existing tools easily.  Of
course, more detailed analysis will be possible if we can create nilfs
specific analysis tools.

Below is an example of event dump with Brendan Gregg's perf-tools
(https://github.com/brendangregg/perf-tools).  Time consumption between
each stage can be obtained.

$ sudo bin/tpoint nilfs2:nilfs2_collection_stage_transition
Tracing nilfs2:nilfs2_collection_stage_transition. Ctrl-C to end.
        segctord-14875 [003] ...1 28311.067794: nilfs2_collection_stage_transition: sci = ffff8800ce6de000 stage = ST_INIT
        segctord-14875 [003] ...1 28311.068139: nilfs2_collection_stage_transition: sci = ffff8800ce6de000 stage = ST_GC
        segctord-14875 [003] ...1 28311.068139: nilfs2_collection_stage_transition: sci = ffff8800ce6de000 stage = ST_FILE
        segctord-14875 [003] ...1 28311.068486: nilfs2_collection_stage_transition: sci = ffff8800ce6de000 stage = ST_IFILE
        segctord-14875 [003] ...1 28311.068540: nilfs2_collection_stage_transition: sci = ffff8800ce6de000 stage = ST_CPFILE
        segctord-14875 [003] ...1 28311.068561: nilfs2_collection_stage_transition: sci = ffff8800ce6de000 stage = ST_SUFILE
        segctord-14875 [003] ...1 28311.068565: nilfs2_collection_stage_transition: sci = ffff8800ce6de000 stage = ST_DAT
        segctord-14875 [003] ...1 28311.068573: nilfs2_collection_stage_transition: sci = ffff8800ce6de000 stage = ST_SR
        segctord-14875 [003] ...1 28311.068574: nilfs2_collection_stage_transition: sci = ffff8800ce6de000 stage = ST_DONE

For capturing transition correctly, this patch adds wrappers for the
member scnt of nilfs_cstage.  With this change, every transition of the
stage can produce trace event in a correct manner.
Signed-off-by: NHitoshi Mitake <mitake.hitoshi@lab.ntt.co.jp>
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

As a nilfs2 volume ages, the amount of available disk space decreases
little by little due to bloat of DAT (disk address translation) metadata
file.  Even if we delete all files in a file system and free their block
addresses from the DAT file through a garbage collection, empty DAT blocks
are not freed.

This fixes the issue by extending the deallocator of block addresses so
that empty data blocks and empty bitmap blocks of DAT are deleted.

The following comparison shows the effect of this patch.  Each shows disk
amount information of a nilfs2 volume that we cleaned out by deleting all
files and running gc after having filled 90% of its capacity.

Before:
Filesystem     1K-blocks     Used Available Use% Mounted on
/dev/sda1      500105212  3022844 472072192   1% /test

After:
Filesystem     1K-blocks     Used Available Use% Mounted on
/dev/sda1      500105212    16380 475078656   1% /test
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This adds delete functions for data blocks of metadata files using bitmap
based allocator.  nilfs_palloc_delete_entry_block() deletes an entry block
(e.g.  block storing dat entries), and nilfs_palloc_delete_bitmap_block()
deletes a bitmap block, respectively.

These helpers are intended to be used in the successive change on
deallocator of block addresses ("nilfs2: free unused dat file blocks
during garbage collection").
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This unfolds nilfs_palloc_group_is_in() helper function into
nilfs_palloc_freev() function to simplify a range check and an index
calculation repeatedy performed in a loop of the function.
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The current implementation of nilfs_palloc_find_available_slot() function
is overkill.  The underlying bit search routine is well optimized, so this
uses it more simply in nilfs_palloc_find_available_slot().
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>