tree 15ded5c1dec040323415c0281bc415ec3ca91cf8
parent 4882abebccb58d68056462b66cea0d7f16169c39
author Gang He <ghe@suse.com> 1517444113 -0800
committer Linus Torvalds <torvalds@linux-foundation.org> 1517447915 -0800

ocfs2: add trimfs lock to avoid duplicated trims in cluster

ocfs2 supports trimming the underlying disk via the fstrim command.  But
there is a problem, ocfs2 is a shared disk cluster file system, if the
user configures a scheduled fstrim job on each file system node, this
will trigger multiple nodes trimming a shared disk simultaneously, which
is very wasteful for CPU and IO consumption.  This also might negatively
affect the lifetime of poor-quality SSD devices.

So we introduce a trimfs dlm lock to communicate with each other in this
case, which will make only one fstrim command to do the trimming on a
shared disk among the cluster.  The fstrim commands from the other nodes
should wait for the first fstrim to finish and return success directly,
to avoid running the same trim on the shared disk again.

Link: http://lkml.kernel.org/r/1513228484-2084-2-git-send-email-ghe@suse.com
Signed-off-by: Gang He <ghe@suse.com>
Reviewed-by: Changwei Ge <ge.changwei@h3c.com>
Cc: Mark Fasheh <mfasheh@versity.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Joseph Qi <jiangqi903@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>