Commit graph

40 commits

Author SHA1 Message Date
Ryusuke Konishi
4e33f9eab0 nilfs2: implement resize ioctl
This adds resize ioctl which makes online resize possible.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
2011-05-10 22:21:46 +09:00
Ryusuke Konishi
e3154e9748 nilfs2: get rid of nilfs_sb_info structure
This directly uses sb->s_fs_info to keep a nilfs filesystem object and
fully removes the intermediate nilfs_sb_info structure.  With this
change, the hierarchy of on-memory structures of nilfs will be
simplified as follows:

Before:
  super_block
       -> nilfs_sb_info
             -> the_nilfs
                   -> cptree --+-> nilfs_root (current file system)
                               +-> nilfs_root (snapshot A)
                               +-> nilfs_root (snapshot B)
                               :
             -> nilfs_sc_info (log writer structure)
After:
  super_block
       -> the_nilfs
             -> cptree --+-> nilfs_root (current file system)
                         +-> nilfs_root (snapshot A)
                         +-> nilfs_root (snapshot B)
                         :
             -> nilfs_sc_info (log writer structure)

The reason why we didn't design so from the beginning is because the
initial shape also differed from the above.  The early hierachy was
composed of "per-mount-point" super_block -> nilfs_sb_info pairs and a
shared nilfs object.  On the kernel 2.6.37, it was changed to the
current shape in order to unify super block instances into one per
device, and this cleanup became applicable as the result.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
2011-03-09 11:54:26 +09:00
Ryusuke Konishi
f7545144c2 nilfs2: use sb instance instead of nilfs_sb_info struct
This replaces sbi uses with direct reference to sb instance.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
2011-03-09 11:05:08 +09:00
Ryusuke Konishi
3fd3fe5aea nilfs2: move log writer onto nilfs object
Log writer is held by the nilfs_sb_info structure.  This moves it into
nilfs object and replaces all uses of NILFS_SC() accessor.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
2011-03-09 11:05:08 +09:00
Ryusuke Konishi
9b1fc4e497 nilfs2: move next generation counter into nilfs object
Moves s_next_generation counter and a spinlock protecting it to nilfs
object from nilfs_sb_info structure.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
2011-03-09 11:05:08 +09:00
Ryusuke Konishi
693dd32122 nilfs2: move s_inode_lock and s_dirty_files into nilfs object
Moves s_inode_lock spinlock and s_dirty_files list to nilfs object
from nilfs_sb_info structure.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
2011-03-09 11:05:07 +09:00
Ryusuke Konishi
574e6c3145 nilfs2: move parameters on nilfs_sb_info into nilfs object
This moves four parameter variables on nilfs_sb_info s_resuid,
s_resgid, s_interval and s_watermark to the nilfs object.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
2011-03-09 11:05:07 +09:00
Ryusuke Konishi
3b2ce58b0f nilfs2: move mount options to nilfs object
This moves mount_opt local variable to nilfs object from nilfs_sb_info
struct.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
2011-03-09 11:05:07 +09:00
Ryusuke Konishi
888da23c2f nilfs2: get rid of loaded flag from nilfs object
NILFS_LOADED flag of the nilfs object is not used now, so this will
remove it.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
2011-01-10 14:05:46 +09:00
Ryusuke Konishi
026a7d63d5 nilfs2: get rid of bdi from nilfs object
Nilfs now can use sb->s_bdi to get backing_dev_info, so we use it
instead of ns_bdi on the nilfs object and remove ns_bdi.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
2010-10-23 09:24:39 +09:00
Ryusuke Konishi
090fd5b101 nilfs2: get rid of back pointer to writable sb instance
Nilfs object holds a back pointer to a writable super block instance
in nilfs->ns_writer, and this became eliminable since sb is now made
per device and all inodes have a valid pointer to it.

This deletes the ns_writer pointer and a reader/writer semaphore
protecting it.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
2010-10-23 09:24:38 +09:00
Ryusuke Konishi
032dbb3b50 nilfs2: see state of root dentry for mount check of snapshots
After applied the patch that unified sb instances, root dentry of
snapshots can be left in dcache even after their trees are unmounted.

The orphan root dentry/inode keeps a root object, and this causes
false positive of nilfs_checkpoint_is_mounted function.

This resolves the issue by having nilfs_checkpoint_is_mounted test
whether the root dentry is busy or not.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
2010-10-23 09:24:38 +09:00
Ryusuke Konishi
c1c1d70920 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>
2010-10-23 09:24:38 +09:00
Ryusuke Konishi
348fe8da13 nilfs2: simplify life cycle management of nilfs object
This stops pre-allocating nilfs object in nilfs_get_sb routine, and
stops managing its life cycle by reference counting.

nilfs_find_or_create_nilfs() function, nilfs->ns_mount_mutex,
nilfs_objects list, and the reference counter will be removed through
the simplification.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
2010-10-23 09:24:36 +09:00
Ryusuke Konishi
f11459ad7d nilfs2: do not allocate multiple super block instances for a device
This stops allocating multiple super block instances for a device.

All snapshots and a current mode mount (i.e. latest tree) will be
controlled with nilfs_root objects that are kept within an sb
instance.

nilfs_get_sb() is rewritten so that it always has a root object for
the latest tree and snapshots make additional root objects.

The root dentry of the latest tree is binded to sb->s_root even if it
isn't attached on a directory.  Root dentries of snapshots or the
latest tree are binded to mnt->mnt_root on which they are mounted.

With this patch, nilfs_find_sbinfo() function, nilfs->ns_supers list,
and nilfs->ns_current back pointer, are deleted.  In addition,
init_nilfs() and load_nilfs() are simplified since they will be called
once for a device, not repeatedly called for mount points.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
2010-10-23 09:24:36 +09:00
Ryusuke Konishi
ba65ae4729 nilfs2: add checkpoint tree to nilfs object
To hold multiple versions of a filesystem in one sb instance, a new
on-memory structure is necessary to handle one or more checkpoints.

This adds a red-black tree of checkpoints to nilfs object, and adds
lookup and create functions for them.

Each checkpoint is represented by "nilfs_root" structure, and this
structure has rb_node to configure the rb-tree.

The nilfs_root object is identified with a checkpoint number.  For
each snapshot, a nilfs_root object is allocated and the checkpoint
number of snapshot is assigned to it.  For a regular mount
(i.e. current mode mount), NILFS_CPTREE_CURRENT_CNO constant is
assigned to the corresponding nilfs_root object.

Each nilfs_root object has an ifile inode and some counters.  These
items will displace those of nilfs_sb_info structure in successive
patches.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
2010-10-23 09:24:34 +09:00
Ryusuke Konishi
263d90cefc nilfs2: remove own inode hash used for GC
This uses inode hash function that vfs provides instead of the own
hash table for caching gc inodes.  This finally removes the own inode
hash from nilfs.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
2010-10-23 09:24:34 +09:00
Ryusuke Konishi
325020477a nilfs2: do not update log cursor for small change
Super blocks of nilfs are periodically overwritten in order to record
the recent log position.  This shortens recovery time after unclean
unmount, but the current implementation performs the update even for a
few blocks of change.  If the filesystem gets small changes slowly and
continually, super blocks may be updated excessively.

This moderates the issue by skipping update of log cursor if it does
not cross a segment boundary.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
2010-07-23 10:02:11 +09:00
Jiro SEKIBA
b2ac86e1a8 nilfs2: sync super blocks in turns
This will sync super blocks in turns instead of syncing duplicate
super blocks at the time.  This will help searching valid super root
when super block is written into disk before log is written, which is
happen when barrier-less block devices are unmounted uncleanly.  In
the situation, old super block likely points to valid log.

This patch introduces ns_sbwcount member to the nilfs object and adds
nilfs_sb_will_flip() function; ns_sbwcount counts how many times super
blocks write back to the disk.  And, nilfs_sb_will_flip() decides
whether flipping required or not based on the count of ns_sbwcount to
sync super blocks asymmetrically.

The following functions are also changed:

 - nilfs_prepare_super(): flips super blocks according to the
   argument.  The argument is calculated by nilfs_sb_will_flip()
   function.

 - nilfs_cleanup_super(): sets "clean" flag to both super blocks if
   they point to the same checkpoint.

To update both of super block information, caller of
nilfs_commit_super must set the information on both super blocks.

Signed-off-by: Jiro SEKIBA <jir@unicus.jp>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
2010-07-23 10:02:11 +09:00
Ryusuke Konishi
57a4bfc486 nilfs2: get rid of ns_free_segments_count
This counter is unused.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
2010-07-23 10:02:09 +09:00
Ryusuke Konishi
92c60ccaf3 nilfs2: add blocksize member to nilfs object
This stores blocksize in nilfs objects for the successive refactoring
of recovery logic.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
2010-07-23 10:02:08 +09:00
Tejun Heo
5a0e3ad6af include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h
percpu.h is included by sched.h and module.h and thus ends up being
included when building most .c files.  percpu.h includes slab.h which
in turn includes gfp.h making everything defined by the two files
universally available and complicating inclusion dependencies.

percpu.h -> slab.h dependency is about to be removed.  Prepare for
this change by updating users of gfp and slab facilities include those
headers directly instead of assuming availability.  As this conversion
needs to touch large number of source files, the following script is
used as the basis of conversion.

  http://userweb.kernel.org/~tj/misc/slabh-sweep.py

The script does the followings.

* Scan files for gfp and slab usages and update includes such that
  only the necessary includes are there.  ie. if only gfp is used,
  gfp.h, if slab is used, slab.h.

* When the script inserts a new include, it looks at the include
  blocks and try to put the new include such that its order conforms
  to its surrounding.  It's put in the include block which contains
  core kernel includes, in the same order that the rest are ordered -
  alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
  doesn't seem to be any matching order.

* If the script can't find a place to put a new include (mostly
  because the file doesn't have fitting include block), it prints out
  an error message indicating which .h file needs to be added to the
  file.

The conversion was done in the following steps.

1. The initial automatic conversion of all .c files updated slightly
   over 4000 files, deleting around 700 includes and adding ~480 gfp.h
   and ~3000 slab.h inclusions.  The script emitted errors for ~400
   files.

2. Each error was manually checked.  Some didn't need the inclusion,
   some needed manual addition while adding it to implementation .h or
   embedding .c file was more appropriate for others.  This step added
   inclusions to around 150 files.

3. The script was run again and the output was compared to the edits
   from #2 to make sure no file was left behind.

4. Several build tests were done and a couple of problems were fixed.
   e.g. lib/decompress_*.c used malloc/free() wrappers around slab
   APIs requiring slab.h to be added manually.

5. The script was run on all .h files but without automatically
   editing them as sprinkling gfp.h and slab.h inclusions around .h
   files could easily lead to inclusion dependency hell.  Most gfp.h
   inclusion directives were ignored as stuff from gfp.h was usually
   wildly available and often used in preprocessor macros.  Each
   slab.h inclusion directive was examined and added manually as
   necessary.

6. percpu.h was updated not to include slab.h.

7. Build test were done on the following configurations and failures
   were fixed.  CONFIG_GCOV_KERNEL was turned off for all tests (as my
   distributed build env didn't work with gcov compiles) and a few
   more options had to be turned off depending on archs to make things
   build (like ipr on powerpc/64 which failed due to missing writeq).

   * x86 and x86_64 UP and SMP allmodconfig and a custom test config.
   * powerpc and powerpc64 SMP allmodconfig
   * sparc and sparc64 SMP allmodconfig
   * ia64 SMP allmodconfig
   * s390 SMP allmodconfig
   * alpha SMP allmodconfig
   * um on x86_64 SMP allmodconfig

8. percpu.h modifications were reverted so that it could be applied as
   a separate patch and serve as bisection point.

Given the fact that I had only a couple of failures from tests on step
6, I'm fairly confident about the coverage of this conversion patch.
If there is a breakage, it's likely to be something in one of the arch
headers which should be easily discoverable easily on most builds of
the specific arch.

Signed-off-by: Tejun Heo <tj@kernel.org>
Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
2010-03-30 22:02:32 +09:00
Ryusuke Konishi
e605f0a724 nilfs2: get rid of s_dirt flag use
This replaces s_dirt flag use in nilfs with a new flag added on the
nilfs object.  The s_dirt flag was used to indicate if
sop->write_super() should be called, however the current version of
nilfs does not use the callback.  Thus, it can be replaced with the
own flag.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Cc: Jiro SEKIBA <jir@unicus.jp>
2010-02-13 12:26:03 +09:00
Jiro SEKIBA
e902ec9906 nilfs2: issue discard request after cleaning segments
This adds a function to send discard requests for given array of
segment numbers, and calls the function when garbage collection
succeeded.

Signed-off-by: Jiro SEKIBA <jir@unicus.jp>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
2010-02-13 12:26:02 +09:00
Ryusuke Konishi
a057d2c011 nilfs2: add helper to get if volume is in a valid state
This adds a helper function, nilfs_valid_fs() which returns if nilfs
is in a valid state or not.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
2009-11-20 10:05:52 +09:00
Jiro SEKIBA
1cf58fa840 nilfs2: shorten freeze period due to GC in write operation v3
This is a re-revised patch to shorten freeze period.
This version include a fix of the bug Konishi-san mentioned last time.

When GC is runnning, GC moves live block to difference segments.
Copying live blocks into memory is done in a transaction,
however it is not necessarily to be in the transaction.
This patch will get the nilfs_ioctl_move_blocks() out from
transaction lock and put it before the transaction.

I ran sysbench fileio test against nilfs partition.
I copied some DVD/CD images and created snapshot to create live blocks
before starting the benchmark.

Followings are summary of rc8 and rc8 w/ the patch of per-request
statistics, which is min/max and avg.  I ran each test three times and
bellow is average of those numers.

According to this benchmark result, average time is slightly degrated.
However, worstcase (max) result is significantly improved.
This can address a few seconds write freeze.

- random write per-request performance of rc8
 min   0.843ms
 max 680.406ms
 avg   3.050ms
- random write per-request performance of rc8 w/ this patch
 min   0.843ms -> 100.00%
 max 380.490ms ->  55.90%
 avg   3.233ms -> 106.00%

- sequential write per-request performance of rc8
 min   0.736ms
 max 774.343ms
 avg   2.883ms
- sequential write per-request performance of rc8 w/ this patch
 min   0.720ms ->  97.80%
 max  644.280ms->  83.20%
 avg   3.130ms -> 108.50%

-----8<-----8<-----nilfs_cleanerd.conf-----8<-----8<-----
protection_period       150
selection_policy        timestamp       # timestamp in ascend order
nsegments_per_clean     2
cleaning_interval       2
retry_interval          60
use_mmap
log_priority            info
-----8<-----8<-----nilfs_cleanerd.conf-----8<-----8<-----

Signed-off-by: Jiro SEKIBA <jir@unicus.jp>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
2009-09-14 18:27:15 +09:00
Jiro SEKIBA
79efdd9411 nilfs2: clean up nilfs_write_super
Separate conditions that check if syncing super block and alternative
super block are required as inline functions to reuse the conditions.

Signed-off-by: Jiro SEKIBA <jir@unicus.jp>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
2009-09-14 18:27:14 +09:00
Ryusuke Konishi
027d6404eb nilfs2: use semaphore to protect pointer to a writable FS-instance
will get rid of nilfs_get_writer() and nilfs_put_writer() pair used to
retain a writable FS-instance for a period.

The pair functions were making up some kind of recursive lock with a
mutex, but they became overkill since the commit
201913ed74.  Furthermore, they caused
the following lockdep warning because the mutex can be released by a
task which didn't lock it:

 =====================================
 [ BUG: bad unlock balance detected! ]
 -------------------------------------
 kswapd0/422 is trying to release lock (&nilfs->ns_writer_mutex) at:
 [<c1359ff5>] mutex_unlock+0x8/0xa
 but there are no more locks to release!

 other info that might help us debug this:
 no locks held by kswapd0/422.

 stack backtrace:
 Pid: 422, comm: kswapd0 Not tainted 2.6.31-rc4-nilfs #51
 Call Trace:
  [<c1358f97>] ? printk+0xf/0x18
  [<c104fea7>] print_unlock_inbalance_bug+0xcc/0xd7
  [<c11578de>] ? prop_put_global+0x3/0x35
  [<c1050195>] lock_release+0xed/0x1dc
  [<c1359ff5>] ? mutex_unlock+0x8/0xa
  [<c1359f83>] __mutex_unlock_slowpath+0xaf/0x119
  [<c1359ff5>] mutex_unlock+0x8/0xa
  [<d1284add>] nilfs_mdt_write_page+0xd8/0xe1 [nilfs2]
  [<c1092653>] shrink_page_list+0x379/0x68d
  [<c109171b>] ? isolate_pages_global+0xb4/0x18c
  [<c1092bd2>] shrink_list+0x26b/0x54b
  [<c10930be>] shrink_zone+0x20c/0x2a2
  [<c10936b7>] kswapd+0x407/0x591
  [<c1091667>] ? isolate_pages_global+0x0/0x18c
  [<c1040603>] ? autoremove_wake_function+0x0/0x33
  [<c10932b0>] ? kswapd+0x0/0x591
  [<c104033b>] kthread+0x69/0x6e
  [<c10402d2>] ? kthread+0x0/0x6e
  [<c1003e33>] kernel_thread_helper+0x7/0x1a

This patch uses a reader/writer semaphore instead of the own lock and
kills this warning.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
2009-09-14 18:27:13 +09:00
Ryusuke Konishi
a924586036 nilfs2: fix oopses with doubly mounted snapshots
will fix kernel oopses like the following:

 # mount -t nilfs2 -r -o cp=20 /dev/sdb1 /test1
 # mount -t nilfs2 -r -o cp=20 /dev/sdb1 /test2
 # umount /test1
 # umount /test2

BUG: sleeping function called from invalid context at arch/x86/mm/fault.c:1069
in_atomic(): 0, irqs_disabled(): 1, pid: 3886, name: umount.nilfs2
1 lock held by umount.nilfs2/3886:
 #0:  (&type->s_umount_key#31){+.+...}, at: [<c10b398a>] deactivate_super+0x52/0x6c
irq event stamp: 1219
hardirqs last  enabled at (1219): [<c135c774>] __mutex_unlock_slowpath+0xf8/0x119
hardirqs last disabled at (1218): [<c135c6d5>] __mutex_unlock_slowpath+0x59/0x119
softirqs last  enabled at (1214): [<c1033316>] __do_softirq+0x1a5/0x1ad
softirqs last disabled at (1205): [<c1033354>] do_softirq+0x36/0x5a
Pid: 3886, comm: umount.nilfs2 Not tainted 2.6.31-rc6 #55
Call Trace:
 [<c1023549>] __might_sleep+0x107/0x10e
 [<c13603c0>] do_page_fault+0x246/0x397
 [<c136017a>] ? do_page_fault+0x0/0x397
 [<c135e753>] error_code+0x6b/0x70
 [<c136017a>] ? do_page_fault+0x0/0x397
 [<c104f805>] ? __lock_acquire+0x91/0x12fd
 [<c1050a62>] ? __lock_acquire+0x12ee/0x12fd
 [<c1050a62>] ? __lock_acquire+0x12ee/0x12fd
 [<c1050b2b>] lock_acquire+0xba/0xdd
 [<d0d17d3f>] ? nilfs_detach_segment_constructor+0x2f/0x2fa [nilfs2]
 [<c135d4fe>] down_write+0x2a/0x46
 [<d0d17d3f>] ? nilfs_detach_segment_constructor+0x2f/0x2fa [nilfs2]
 [<d0d17d3f>] nilfs_detach_segment_constructor+0x2f/0x2fa [nilfs2]
 [<c104ea2c>] ? mark_held_locks+0x43/0x5b
 [<c104ecb1>] ? trace_hardirqs_on_caller+0x10b/0x133
 [<c104ece4>] ? trace_hardirqs_on+0xb/0xd
 [<d0d09ac1>] nilfs_put_super+0x2f/0xca [nilfs2]
 [<c10b3352>] generic_shutdown_super+0x49/0xb8
 [<c10b33de>] kill_block_super+0x1d/0x31
 [<c10e6599>] ? vfs_quota_off+0x0/0x12
 [<c10b398f>] deactivate_super+0x57/0x6c
 [<c10c4bc3>] mntput_no_expire+0x8c/0xb4
 [<c10c5094>] sys_umount+0x27f/0x2a4
 [<c10c50c6>] sys_oldumount+0xd/0xf
 [<c10031a4>] sysenter_do_call+0x12/0x38
 ...

This turns out to be a bug brought by an -rc1 patch ("nilfs2: simplify
remaining sget() use").

In the patch, a new "put resource" function, nilfs_put_sbinfo()
was introduced to delay freeing nilfs_sb_info struct.

But the nilfs_put_sbinfo() mistakenly used atomic_dec_and_test()
function to check the reference count, and it caused the nilfs_sb_info
was freed when user mounted a snapshot twice.

This bug also suggests there was unseen memory leak in usual mount
/umount operations for nilfs.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
2009-08-19 02:10:13 +09:00
Ryusuke Konishi
aa7dfb8954 nilfs2: get rid of bd_mount_sem use from nilfs
This will remove every bd_mount_sem use in nilfs.

The intended exclusion control was replaced by the previous patch
("nilfs2: correct exclusion control in nilfs_remount function") for
nilfs_remount(), and this patch will replace remains with a new mutex
that this inserts in nilfs object.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2009-06-11 21:36:18 -04:00
Ryusuke Konishi
e59399d010 nilfs2: correct exclusion control in nilfs_remount function
nilfs_remount() changes mount state of a superblock instance.  Even
though nilfs accesses other superblock instances during mount or
remount, the mount state was not properly protected in
nilfs_remount().

Moreover, nilfs_remount() has a lock order reversal problem;
nilfs_get_sb() holds:

  1. bdev->bd_mount_sem
  2. sb->s_umount  (sget acquires)

and nilfs_remount() holds:

  1. sb->s_umount  (locked by the caller in vfs)
  2. bdev->bd_mount_sem

To avoid these problems, this patch divides a semaphore protecting
super block instances from nilfs->ns_sem, and applies it to the mount
state protection in nilfs_remount().

With this change, bd_mount_sem use is removed from nilfs_remount() and
the lock order reversal will be resolved.  And the new rw-semaphore,
nilfs->ns_super_sem will properly protect the mount state except the
modification from nilfs_error function.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2009-06-11 21:36:18 -04:00
Ryusuke Konishi
6dd4740662 nilfs2: simplify remaining sget() use
This simplifies the test function passed on the remaining sget()
callsite in nilfs.

Instead of checking mount type (i.e. ro-mount/rw-mount/snapshot mount)
in the test function passed to sget(), this patch first looks up the
nilfs_sb_info struct which the given mount type matches, and then
acquires the super block instance holding the nilfs_sb_info.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2009-06-11 21:36:18 -04:00
Ryusuke Konishi
3f82ff5516 nilfs2: get rid of sget use for checking if current mount is present
This stops using sget() for checking if an r/w-mount or an r/o-mount
exists on the device.  This elimination uses a back pointer to the
current mount added to nilfs object.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2009-06-11 21:36:17 -04:00
Ryusuke Konishi
33c8e57c86 nilfs2: get rid of sget use for acquiring nilfs object
This will change the way to obtain nilfs object in nilfs_get_sb()
function.

Previously, a preliminary sget() call was performed, and the nilfs
object was acquired from a super block instance found by the sget()
call.

This patch, instead, instroduces a new dedicated function
find_or_create_nilfs(); as the name implies, the function finds an
existent nilfs object from a global list or creates a new one if no
object is found on the device.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2009-06-11 21:36:17 -04:00
Ryusuke Konishi
e339ad31f5 nilfs2: introduce secondary super block
The former versions didn't have extra super blocks.  This improves the
weak point by introducing another super block at unused region in tail of
the partition.

This doesn't break disk format compatibility; older versions just ingore
the secondary super block, and new versions just recover it if it doesn't
exist.  The partition created by an old mkfs may not have unused region,
but in that case, the secondary super block will not be added.

This doesn't make more redundant copies of the super block; it is a future
work.

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>
2009-04-07 08:31:20 -07:00
Ryusuke Konishi
cece552074 nilfs2: simplify handling of active state of segments
will reduce some lines of segment constructor.  Previously, the state was
complexly controlled through a list of segments in order to keep
consistency in meta data of usage state of segments.  Instead, this
presents ``calculated'' active flags to userland cleaner program and stop
maintaining its real flag on disk.

Only by this fake flag, the cleaner cannot exactly know if each segment is
reclaimable or not.  However, the recent extension of nilfs_sustat ioctl
struct (nilfs2-extend-nilfs_sustat-ioctl-struct.patch) can prevent the
cleaner from reclaiming in-use segment wrongly.

So, now I can apply this for simplification.

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>
2009-04-07 08:31:20 -07:00
Ryusuke Konishi
2c2e52fc4f nilfs2: extend nilfs_sustat ioctl struct
This adds a new argument to the nilfs_sustat structure.

The extended field allows to delete volatile active state of segments,
which was needed to protect freshly-created segments from garbage
collection but has confused code dealing with segments.  This
extension alleviates the mess and gives room for further
simplifications.

The volatile active flag is not persistent, so it's eliminable on this
occasion without affecting compatibility other than the ioctl change.

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>
2009-04-07 08:31:19 -07:00
Ryusuke Konishi
1088dcf4c3 nilfs2: remove timedwait ioctl command
This removes NILFS_IOCTL_TIMEDWAIT command from ioctl interface along
with the related flags and wait queue.

The command is terrible because it just sleeps in the ioctl.  I prefer
to avoid this by devising means of event polling in userland program.
By reconsidering the userland GC daemon, I found this is possible
without changing behaviour of the daemon and sacrificing efficiency.

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>
2009-04-07 08:31:18 -07:00
Ryusuke Konishi
47420c7998 nilfs2: avoid double error caused by nilfs_transaction_end
Pekka Enberg pointed out that double error handlings found after
nilfs_transaction_end() can be avoided by separating abort operation:

 OK, I don't understand this. The only way nilfs_transaction_end() can
 fail is if we have NILFS_TI_SYNC set and we fail to construct the
 segment. But why do we want to construct a segment if we don't commit?

 I guess what I'm asking is why don't we have a separate
 nilfs_transaction_abort() function that can't fail for the erroneous
 case to avoid this double error value tracking thing?

This does the separation and renames nilfs_transaction_end() to
nilfs_transaction_commit() for clarification.

Since, some calls of these functions were used just for exclusion control
against the segment constructor, they are replaced with semaphore
operations.

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>
2009-04-07 08:31:17 -07:00
Ryusuke Konishi
65b4643d3b nilfs2: add inode and other major structures
This adds the following common structures of the NILFS2 file system.

* nilfs_inode_info structure:
  gives on-memory inode.

* nilfs_sb_info structure:
  keeps per-mount state and a special inode for the ifile.
  This structure is attached to the super_block structure.

* the_nilfs structure:
  keeps shared state and locks among a read/write mount and snapshot
  mounts.  This keeps special inodes for the sufile, cpfile, dat, and
  another dat inode used during GC (gcdat).  This also has a hash table
  of dummy inodes to cache disk blocks during GC (gcinodes).

* nilfs_transaction_info structure:
  keeps per task state while nilfs is writing logs or doing indivisible
  inode or namespace operations.  This structure is used to identify
  context during log making and store nest level of the lock which
  ensures atomicity of file system operations.

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>
2009-04-07 08:31:12 -07:00