Commit Graph

15 Commits

Author SHA1 Message Date
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