On Sun, 13 Jan 2013 16:07:23 +0900 (JST) Ryusuke Konishi <konishi.ryusuke@xxxxxxxxxxxxx> wrote: > On Sat, 12 Jan 2013 19:34:48 +0400, Vyacheslav Dubeyko wrote: > > From: Vyacheslav Dubeyko <slava@xxxxxxxxxxx> > > Subject: [PATCH] nilfs2: fix very long mount time issue > > > > DESCRIPTION: > > It exists 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@xxxxxxxxx> > > Signed-off-by: Vyacheslav Dubeyko <slava@xxxxxxxxxxx> > > Tested-by: Vyacheslav Dubeyko <slava@xxxxxxxxxxx> > > Acked-by: Ryusuke Konishi <konishi.ryusuke@xxxxxxxxxxxxx> > > Thanks, Vyacheslav. I confirmed the issue and could reproduce it. > Your patch fixed it. > > Andrew, please apply. I added a Cc:stable so the fix will be backported into earlier kernels. 40 minutes mount time is pretty bad! -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
