linux/fs/nilfs2
Vyacheslav Dubeyko a9bae18954 nilfs2: fix fix very long mount time issue
There exists a situation when GC can work in background alone without
any other filesystem activity during significant time.

The nilfs_clean_segments() method calls nilfs_segctor_construct() that
updates superblocks in the case of NILFS_SC_SUPER_ROOT and
THE_NILFS_DISCONTINUED flags are set.  But when GC is working alone the
nilfs_clean_segments() is called with unset THE_NILFS_DISCONTINUED flag.
As a result, the update of superblocks doesn't occurred all this time
and in the case of SPOR superblocks keep very old values of last super
root placement.

SYMPTOMS:

Trying to mount a NILFS2 volume after SPOR in such environment ends with
very long mounting time (it can achieve about several hours in some
cases).

REPRODUCING PATH:

1. It needs to use external USB HDD, disable automount and doesn't
   make any additional filesystem activity on the NILFS2 volume.

2. Generate temporary file with size about 100 - 500 GB (for example,
   dd if=/dev/zero of=<file_name> bs=1073741824 count=200).  The size of
   file defines duration of GC working.

3. Then it needs to delete file.

4. Start GC manually by means of command "nilfs-clean -p 0".  When you
   start GC by means of such way then, at the end, superblocks is updated
   by once.  So, for simulation of SPOR, it needs to wait sometime (15 -
   40 minutes) and simply switch off USB HDD manually.

5. Switch on USB HDD again and try to mount NILFS2 volume.  As a
   result, NILFS2 volume will mount during very long time.

REPRODUCIBILITY: 100%

FIX:

This patch adds checking that superblocks need to update and set
THE_NILFS_DISCONTINUED flag before nilfs_clean_segments() call.

Reported-by: Sergey Alexandrov <splavgm@gmail.com>
Signed-off-by: Vyacheslav Dubeyko <slava@dubeyko.com>
Tested-by: Vyacheslav Dubeyko <slava@dubeyko.com>
Acked-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Tested-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-02-05 20:38:46 +11:00
..
alloc.c nilfs2: use mark_buffer_dirty to mark btnode or meta data dirty 2011-05-10 22:21:57 +09:00
alloc.h nilfs2: add omitted comments for different structures in driver implementation 2012-07-30 17:25:19 -07:00
bmap.c nilfs2: get rid of NILFS_I_NILFS 2011-05-10 22:21:56 +09:00
bmap.h nilfs2: add omitted comments for different structures in driver implementation 2012-07-30 17:25:19 -07:00
btnode.c nilfs2: use mark_buffer_dirty to mark btnode or meta data dirty 2011-05-10 22:21:57 +09:00
btnode.h nilfs2: add omitted comments for different structures in driver implementation 2012-07-30 17:25:19 -07:00
btree.c nilfs2: fix missing block address termination in btree node shrinking 2011-06-11 15:51:15 +09:00
btree.h
cpfile.c nilfs2: fix timing issue between rmcp and chcp ioctls 2012-07-30 17:25:19 -07:00
cpfile.h
dat.c nilfs2: add omitted comments for different structures in driver implementation 2012-07-30 17:25:19 -07:00
dat.h
dir.c nilfs2: remove the second argument of k[un]map_atomic() 2012-03-20 21:48:24 +08:00
direct.c nilfs2: record used amount of each checkpoint in checkpoint list 2011-03-08 14:58:31 +09:00
direct.h
export.h nilfs2: add omitted comments for different structures in driver implementation 2012-07-30 17:25:19 -07:00
file.c nilfs2: drop vmtruncate 2012-12-20 18:40:54 -05:00
gcinode.c nilfs2: ensure proper cache clearing for gc-inodes 2012-06-20 14:39:35 -07:00
ifile.c nilfs2: add omitted comments for different structures in driver implementation 2012-07-30 17:25:19 -07:00
ifile.h
inode.c nilfs2: drop vmtruncate 2012-12-20 18:40:54 -05:00
ioctl.c nilfs2: fix fix very long mount time issue 2013-02-05 20:38:46 +11:00
Kconfig
Makefile
mdt.c nilfs2: remove the second argument of k[un]map_atomic() 2012-03-20 21:48:24 +08:00
mdt.h nilfs2: add omitted comments for different structures in driver implementation 2012-07-30 17:25:19 -07:00
namei.c don't pass nameidata to ->create() 2012-07-14 16:34:47 +04:00
nilfs.h nilfs2: drop vmtruncate 2012-12-20 18:40:54 -05:00
page.c mm: redefine address_space.assoc_mapping 2012-12-11 17:22:26 -08:00
page.h nilfs2: use mark_buffer_dirty to mark btnode or meta data dirty 2011-05-10 22:21:57 +09:00
recovery.c nilfs2: drop vmtruncate 2012-12-20 18:40:54 -05:00
segbuf.c nilfs2: remove the second argument of k[un]map_atomic() 2012-03-20 21:48:24 +08:00
segbuf.h
segment.c nilfs2: Convert to new freezing mechanism 2012-07-31 09:45:52 +04:00
segment.h nilfs2: get rid of private page allocator 2011-05-10 22:21:44 +09:00
sufile.c nilfs2: add omitted comments for different structures in driver implementation 2012-07-30 17:25:19 -07:00
sufile.h nilfs2: get rid of NILFS_I_NILFS 2011-05-10 22:21:56 +09:00
super.c fs: push rcu_barrier() from deactivate_locked_super() to filesystems 2012-10-02 21:35:55 -04:00
the_nilfs.c nilfs2: fix deadlock issue between chcp and thaw ioctls 2012-07-30 17:25:19 -07:00
the_nilfs.h nilfs2: nuke write_super from comments 2012-08-04 12:15:38 +04:00