From 1bab0de0274fbe8c8ac92179e6705584c55ed169 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Thu, 27 Aug 2015 14:16:54 +0200 Subject: dm-mpath, scsi_dh: don't let dm detach device handlers While allowing dm-mpath to attach device handlers is a functionality we need for backwards compatibility reason there is no reason to reference count them and detach them if dm-mpath stops using the device for some reason. If the device handler works for the given device it can just stay attached, and we can take the retain_hw_handler codepath. Signed-off-by: Christoph Hellwig Acked-by: Mike Snitzer Acked-by: Hannes Reinecke Signed-off-by: James Bottomley --- drivers/md/dm-mpath.c | 21 ++++++--------------- 1 file changed, 6 insertions(+), 15 deletions(-) (limited to 'drivers/md') diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c index eff7bdd7731d..a9f58fdb5d69 100644 --- a/drivers/md/dm-mpath.c +++ b/drivers/md/dm-mpath.c @@ -159,12 +159,9 @@ static struct priority_group *alloc_priority_group(void) static void free_pgpaths(struct list_head *pgpaths, struct dm_target *ti) { struct pgpath *pgpath, *tmp; - struct multipath *m = ti->private; list_for_each_entry_safe(pgpath, tmp, pgpaths, list) { list_del(&pgpath->list); - if (m->hw_handler_name) - scsi_dh_detach(bdev_get_queue(pgpath->path.dev->bdev)); dm_put_device(ti, pgpath->path.dev); free_pgpath(pgpath); } @@ -580,6 +577,7 @@ static struct pgpath *parse_path(struct dm_arg_set *as, struct path_selector *ps q = bdev_get_queue(p->path.dev->bdev); if (m->retain_attached_hw_handler) { +retain: attached_handler_name = scsi_dh_attached_handler_name(q, GFP_KERNEL); if (attached_handler_name) { /* @@ -599,20 +597,14 @@ static struct pgpath *parse_path(struct dm_arg_set *as, struct path_selector *ps } if (m->hw_handler_name) { - /* - * Increments scsi_dh reference, even when using an - * already-attached handler. - */ r = scsi_dh_attach(q, m->hw_handler_name); if (r == -EBUSY) { - /* - * Already attached to different hw_handler: - * try to reattach with correct one. - */ - scsi_dh_detach(q); - r = scsi_dh_attach(q, m->hw_handler_name); - } + char b[BDEVNAME_SIZE]; + printk(KERN_INFO "dm-mpath: retaining handler on device %s\n", + bdevname(p->path.dev->bdev, b)); + goto retain; + } if (r < 0) { ti->error = "error attaching hardware handler"; dm_put_device(ti, p->path.dev); @@ -624,7 +616,6 @@ static struct pgpath *parse_path(struct dm_arg_set *as, struct path_selector *ps if (r < 0) { ti->error = "unable to set hardware " "handler parameters"; - scsi_dh_detach(q); dm_put_device(ti, p->path.dev); goto bad; } -- cgit v1.2.3 From 566079c849cfe538e908c44ac11a9c4638db8f91 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Thu, 27 Aug 2015 14:16:55 +0200 Subject: dm-mpath, scsi_dh: request scsi_dh modules in scsi_dh, not dm-mpath This way we can reused the same code any attachment method, not just those requested from dm-mpath. [jejb: fixup checkpatch error] Signed-off-by: Christoph Hellwig Reviewed-by: Martin K. Petersen Reviewed-by: Hannes Reinecke Acked-by: Mike Snitzer Signed-off-by: James Bottomley --- drivers/md/dm-mpath.c | 6 ------ drivers/scsi/device_handler/scsi_dh.c | 36 ++++++++++++++++++----------------- include/scsi/scsi_dh.h | 5 ----- 3 files changed, 19 insertions(+), 28 deletions(-) (limited to 'drivers/md') diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c index a9f58fdb5d69..5a67671a3973 100644 --- a/drivers/md/dm-mpath.c +++ b/drivers/md/dm-mpath.c @@ -725,12 +725,6 @@ static int parse_hw_handler(struct dm_arg_set *as, struct multipath *m) return 0; m->hw_handler_name = kstrdup(dm_shift_arg(as), GFP_KERNEL); - if (!try_then_request_module(scsi_dh_handler_exist(m->hw_handler_name), - "scsi_dh_%s", m->hw_handler_name)) { - ti->error = "unknown hardware handler type"; - ret = -EINVAL; - goto fail; - } if (hw_argc > 1) { char *p; diff --git a/drivers/scsi/device_handler/scsi_dh.c b/drivers/scsi/device_handler/scsi_dh.c index 869b5bd1ad25..3dfef5b0d298 100644 --- a/drivers/scsi/device_handler/scsi_dh.c +++ b/drivers/scsi/device_handler/scsi_dh.c @@ -29,7 +29,7 @@ static DEFINE_SPINLOCK(list_lock); static LIST_HEAD(scsi_dh_list); -static struct scsi_device_handler *get_device_handler(const char *name) +static struct scsi_device_handler *__scsi_dh_lookup(const char *name) { struct scsi_device_handler *tmp, *found = NULL; @@ -44,6 +44,19 @@ static struct scsi_device_handler *get_device_handler(const char *name) return found; } +static struct scsi_device_handler *scsi_dh_lookup(const char *name) +{ + struct scsi_device_handler *dh; + + dh = __scsi_dh_lookup(name); + if (!dh) { + request_module(name); + dh = __scsi_dh_lookup(name); + } + + return dh; +} + /* * device_handler_match_function - Match a device handler to a device * @sdev - SCSI device to be tested @@ -158,7 +171,8 @@ store_dh_state(struct device *dev, struct device_attribute *attr, /* * Attach to a device handler */ - if (!(scsi_dh = get_device_handler(buf))) + scsi_dh = scsi_dh_lookup(buf); + if (!scsi_dh) return err; err = scsi_dh_handler_attach(sdev, scsi_dh); } else { @@ -322,8 +336,7 @@ static int scsi_dh_notifier_remove(struct device *dev, void *data) */ int scsi_register_device_handler(struct scsi_device_handler *scsi_dh) { - - if (get_device_handler(scsi_dh->name)) + if (__scsi_dh_lookup(scsi_dh->name)) return -EBUSY; if (!scsi_dh->attach || !scsi_dh->detach) @@ -350,7 +363,7 @@ EXPORT_SYMBOL_GPL(scsi_register_device_handler); int scsi_unregister_device_handler(struct scsi_device_handler *scsi_dh) { - if (!get_device_handler(scsi_dh->name)) + if (!__scsi_dh_lookup(scsi_dh->name)) return -ENODEV; bus_for_each_dev(&scsi_bus_type, NULL, scsi_dh, @@ -454,17 +467,6 @@ int scsi_dh_set_params(struct request_queue *q, const char *params) } EXPORT_SYMBOL_GPL(scsi_dh_set_params); -/* - * scsi_dh_handler_exist - Return TRUE(1) if a device handler exists for - * the given name. FALSE(0) otherwise. - * @name - name of the device handler. - */ -int scsi_dh_handler_exist(const char *name) -{ - return (get_device_handler(name) != NULL); -} -EXPORT_SYMBOL_GPL(scsi_dh_handler_exist); - /* * scsi_dh_attach - Attach device handler * @q - Request queue that is associated with the scsi_device @@ -478,7 +480,7 @@ int scsi_dh_attach(struct request_queue *q, const char *name) struct scsi_device_handler *scsi_dh; int err = 0; - scsi_dh = get_device_handler(name); + scsi_dh = scsi_dh_lookup(name); if (!scsi_dh) return -EINVAL; diff --git a/include/scsi/scsi_dh.h b/include/scsi/scsi_dh.h index 99c9196fe606..966b921135b5 100644 --- a/include/scsi/scsi_dh.h +++ b/include/scsi/scsi_dh.h @@ -57,7 +57,6 @@ enum { }; #if defined(CONFIG_SCSI_DH) || defined(CONFIG_SCSI_DH_MODULE) extern int scsi_dh_activate(struct request_queue *, activate_complete, void *); -extern int scsi_dh_handler_exist(const char *); extern int scsi_dh_attach(struct request_queue *, const char *); extern const char *scsi_dh_attached_handler_name(struct request_queue *, gfp_t); extern int scsi_dh_set_params(struct request_queue *, const char *); @@ -68,10 +67,6 @@ static inline int scsi_dh_activate(struct request_queue *req, fn(data, 0); return 0; } -static inline int scsi_dh_handler_exist(const char *name) -{ - return 0; -} static inline int scsi_dh_attach(struct request_queue *req, const char *name) { return SCSI_DH_NOSYS; -- cgit v1.2.3 From 294ab783ad98066b87296db1311c7ba2a60206a5 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Wed, 9 Sep 2015 18:04:18 +0200 Subject: scsi_dh: fix randconfig build error It looks like the Kconfig check that was meant to fix this (commit fe9233fb6914a0eb20166c967e3020f7f0fba2c9 [SCSI] scsi_dh: fix kconfig related build errors) was actually reversed, but no-one noticed until the new set of patches which separated DM and SCSI_DH). Fixes: fe9233fb6914a0eb20166c967e3020f7f0fba2c9 Signed-off-by: Christoph Hellwig Tested-by: Mike Snitzer Signed-off-by: James Bottomley --- drivers/md/Kconfig | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/md') diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig index b59727309072..e9ea681129df 100644 --- a/drivers/md/Kconfig +++ b/drivers/md/Kconfig @@ -393,7 +393,7 @@ config DM_MULTIPATH # of SCSI_DH if the latter isn't defined but if # it is, DM_MULTIPATH must depend on it. We get a build # error if SCSI_DH=m and DM_MULTIPATH=y - depends on SCSI_DH || !SCSI_DH + depends on !SCSI_DH || SCSI ---help--- Allow volume managers to support multipath hardware. -- cgit v1.2.3