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
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
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.
This patch adds checking that superblocks need to update and set
THE_NILFS_DISCONTINUED flag before nilfs_clean_segments() call.
Reported-by: Sergey Alexandrov <email@example.com>
Signed-off-by: Vyacheslav Dubeyko <firstname.lastname@example.org>
Tested-by: Vyacheslav Dubeyko <email@example.com>
Acked-by: Ryusuke Konishi <firstname.lastname@example.org>
Tested-by: Ryusuke Konishi <email@example.com>
Signed-off-by: Andrew Morton <firstname.lastname@example.org>
Signed-off-by: Linus Torvalds <email@example.com>
1 file changed