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author | Vyacheslav Dubeyko <slava@dubeyko.com> | 2013-02-04 14:28:41 -0800 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-02-05 20:38:46 +1100 |
commit | a9bae189542e71f91e61a4428adf6e5a7dfe8063 (patch) | |
tree | 4468b0d8bb50bfe762a02b9fd609c4265fef610d /mm/huge_memory.c | |
parent | 6edacf05c8362f4c368991b55d85e8122cfc9a24 (diff) | |
download | linux-a9bae189542e71f91e61a4428adf6e5a7dfe8063.tar.bz2 |
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>
Diffstat (limited to 'mm/huge_memory.c')
0 files changed, 0 insertions, 0 deletions