From 3e9f1be1b4079bfe689ef6be5174f3177b3fd2aa Mon Sep 17 00:00:00 2001 From: Hannes Reinecke Date: Fri, 28 Feb 2014 15:33:45 +0100 Subject: [PATCH] dm mpath: remove process_queued_ios() process_queued_ios() has served 3 functions: 1) select pg and pgpath if none is selected 2) start pg_init if requested 3) dispatch queued IOs when pg is ready Basically, a call to queue_work(process_queued_ios) can be replaced by dm_table_run_md_queue_async(), which runs request queue and ends up calling map_io(), which does 1), 2) and 3). Exception is when !pg_ready() (which means either pg_init is running or requested), then multipath_busy() prevents map_io() being called from request_fn. If pg_init is running, it should be ok as long as pg_init_done() does the right thing when pg_init is completed, I.e.: restart pg_init if !pg_ready() or call dm_table_run_md_queue_async() to kick map_io(). If pg_init is requested, we have to make sure the request is detected and pg_init will be started. pg_init is requested in 3 places: a) __choose_pgpath() in map_io() b) __choose_pgpath() in multipath_ioctl() c) pg_init retry in pg_init_done() a) is ok because map_io() calls __pg_init_all_paths(), which does 2). b) needs a call to __pg_init_all_paths(), which does 2). c) needs a call to __pg_init_all_paths(), which does 2). So this patch removes process_queued_ios() and ensures that __pg_init_all_paths() is called at the appropriate locations. Signed-off-by: Hannes Reinecke Signed-off-by: Mike Snitzer Reviewed-by: Jun'ichi Nomura --- drivers/md/dm-mpath.c | 69 +++++++++++++++++-------------------------- 1 file changed, 27 insertions(+), 42 deletions(-) diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c index e1c3ed31c9df..1c6a3f8da24d 100644 --- a/drivers/md/dm-mpath.c +++ b/drivers/md/dm-mpath.c @@ -93,8 +93,6 @@ struct multipath { unsigned pg_init_count; /* Number of times pg_init called */ unsigned pg_init_delay_msecs; /* Number of msecs before pg_init retry */ - struct work_struct process_queued_ios; - struct work_struct trigger_event; /* @@ -119,7 +117,6 @@ typedef int (*action_fn) (struct pgpath *pgpath); static struct kmem_cache *_mpio_cache; static struct workqueue_struct *kmultipathd, *kmpath_handlerd; -static void process_queued_ios(struct work_struct *work); static void trigger_event(struct work_struct *work); static void activate_path(struct work_struct *work); static int __pgpath_busy(struct pgpath *pgpath); @@ -197,7 +194,6 @@ static struct multipath *alloc_multipath(struct dm_target *ti) spin_lock_init(&m->lock); m->queue_io = 1; m->pg_init_delay_msecs = DM_PG_INIT_DELAY_DEFAULT; - INIT_WORK(&m->process_queued_ios, process_queued_ios); INIT_WORK(&m->trigger_event, trigger_event); init_waitqueue_head(&m->pg_init_wait); mutex_init(&m->work_mutex); @@ -254,16 +250,21 @@ static void clear_mapinfo(struct multipath *m, union map_info *info) * Path selection *-----------------------------------------------*/ -static void __pg_init_all_paths(struct multipath *m) +static int __pg_init_all_paths(struct multipath *m) { struct pgpath *pgpath; unsigned long pg_init_delay = 0; if (m->pg_init_in_progress || m->pg_init_disabled) - return; + return 0; m->pg_init_count++; m->pg_init_required = 0; + + /* Check here to reset pg_init_required */ + if (!m->current_pg) + return 0; + if (m->pg_init_delay_retry) pg_init_delay = msecs_to_jiffies(m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT ? m->pg_init_delay_msecs : DM_PG_INIT_DELAY_MSECS); @@ -275,6 +276,7 @@ static void __pg_init_all_paths(struct multipath *m) pg_init_delay)) m->pg_init_in_progress++; } + return m->pg_init_in_progress; } static void __switch_pg(struct multipath *m, struct pgpath *pgpath) @@ -436,40 +438,13 @@ static int queue_if_no_path(struct multipath *m, unsigned queue_if_no_path, m->saved_queue_if_no_path = queue_if_no_path; m->queue_if_no_path = queue_if_no_path; if (!m->queue_if_no_path) - queue_work(kmultipathd, &m->process_queued_ios); + dm_table_run_md_queue_async(m->ti->table); spin_unlock_irqrestore(&m->lock, flags); return 0; } -static void process_queued_ios(struct work_struct *work) -{ - struct multipath *m = - container_of(work, struct multipath, process_queued_ios); - struct pgpath *pgpath = NULL; - unsigned must_queue = 1; - unsigned long flags; - - spin_lock_irqsave(&m->lock, flags); - - if (!m->current_pgpath) - __choose_pgpath(m, 0); - - pgpath = m->current_pgpath; - - if ((pgpath && !m->queue_io) || - (!pgpath && !m->queue_if_no_path)) - must_queue = 0; - - if (pgpath && m->pg_init_required) - __pg_init_all_paths(m); - - spin_unlock_irqrestore(&m->lock, flags); - if (!must_queue) - dm_table_run_md_queue_async(m->ti->table); -} - /* * An event is triggered whenever a path is taken out of use. * Includes path failure and PG bypass. @@ -1016,7 +991,7 @@ static int reinstate_path(struct pgpath *pgpath) if (!m->nr_valid_paths++) { m->current_pgpath = NULL; - queue_work(kmultipathd, &m->process_queued_ios); + dm_table_run_md_queue_async(m->ti->table); } else if (m->hw_handler_name && (m->current_pg == pgpath->pg)) { if (queue_work(kmpath_handlerd, &pgpath->activate_path.work)) m->pg_init_in_progress++; @@ -1212,11 +1187,12 @@ static void pg_init_done(void *data, int errors) /* Activations of other paths are still on going */ goto out; - if (!m->pg_init_required) - m->queue_io = 0; - - m->pg_init_delay_retry = delay_retry; - queue_work(kmultipathd, &m->process_queued_ios); + if (m->pg_init_required) { + m->pg_init_delay_retry = delay_retry; + if (__pg_init_all_paths(m)) + goto out; + } + m->queue_io = 0; /* * Wake up any thread waiting to suspend. @@ -1592,8 +1568,17 @@ static int multipath_ioctl(struct dm_target *ti, unsigned int cmd, r = err; } - if (r == -ENOTCONN && !fatal_signal_pending(current)) - queue_work(kmultipathd, &m->process_queued_ios); + if (r == -ENOTCONN && !fatal_signal_pending(current)) { + spin_lock_irqsave(&m->lock, flags); + if (!m->current_pg) { + /* Path status changed, redo selection */ + __choose_pgpath(m, 0); + } + if (m->pg_init_required) + __pg_init_all_paths(m); + spin_unlock_irqrestore(&m->lock, flags); + dm_table_run_md_queue_async(m->ti->table); + } return r ? : __blkdev_driver_ioctl(bdev, mode, cmd, arg); }