From 86f1152b117a404229fd6f08ec3faca779f37b92 Mon Sep 17 00:00:00 2001 From: Benjamin Marzinski Date: Wed, 13 Aug 2014 13:53:43 -0500 Subject: [PATCH] dm: allow active and inactive tables to share dm_devs Until this change, when loading a new DM table, DM core would re-open all of the devices in the DM table. Now, DM core will avoid redundant device opens (and closes when destroying the old table) if the old table already has a device open using the same mode. This is achieved by managing reference counts on the table_devices that DM core now stores in the mapped_device structure (rather than in the dm_table structure). So a mapped_device's active and inactive dm_tables' dm_dev lists now just point to the dm_devs stored in the mapped_device's table_devices list. This improvement in DM core's device reference counting has the side-effect of fixing a long-standing limitation of the multipath target: a DM multipath table couldn't include any paths that were unusable (failed). For example: if all paths have failed and you add a new, working, path to the table; you can't use it since the table load would fail due to it still containing failed paths. Now a re-load of a multipath table can include failed devices and when those devices become active again they can be used instantly. The device list code in dm.c isn't a straight copy/paste from the code in dm-table.c, but it's very close (aside from some variable renames). One subtle difference is that find_table_device for the tables_devices list will only match devices with the same name and mode. This is because we don't want to upgrade a device's mode in the active table when an inactive table is loaded. Access to the mapped_device structure's tables_devices list requires a mutex (tables_devices_lock), so that tables cannot be created and destroyed concurrently. Signed-off-by: Benjamin Marzinski Signed-off-by: Mike Snitzer --- drivers/md/dm-ioctl.c | 2 +- drivers/md/dm-table.c | 102 +++++++++------------------ drivers/md/dm.c | 126 ++++++++++++++++++++++++++++++++++ drivers/md/dm.h | 5 +- include/uapi/linux/dm-ioctl.h | 4 +- 5 files changed, 167 insertions(+), 72 deletions(-) diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c index 51521429fb59..0be9381365d7 100644 --- a/drivers/md/dm-ioctl.c +++ b/drivers/md/dm-ioctl.c @@ -1418,7 +1418,7 @@ static void retrieve_deps(struct dm_table *table, deps->count = count; count = 0; list_for_each_entry (dd, dm_table_get_devices(table), list) - deps->dev[count++] = huge_encode_dev(dd->dm_dev.bdev->bd_dev); + deps->dev[count++] = huge_encode_dev(dd->dm_dev->bdev->bd_dev); param->data_size = param->data_start + needed; } diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c index f9c6cb8dbcf8..b2bd1ebf4562 100644 --- a/drivers/md/dm-table.c +++ b/drivers/md/dm-table.c @@ -210,15 +210,16 @@ int dm_table_create(struct dm_table **result, fmode_t mode, return 0; } -static void free_devices(struct list_head *devices) +static void free_devices(struct list_head *devices, struct mapped_device *md) { struct list_head *tmp, *next; list_for_each_safe(tmp, next, devices) { struct dm_dev_internal *dd = list_entry(tmp, struct dm_dev_internal, list); - DMWARN("dm_table_destroy: dm_put_device call missing for %s", - dd->dm_dev.name); + DMWARN("%s: dm_table_destroy: dm_put_device call missing for %s", + dm_device_name(md), dd->dm_dev->name); + dm_put_table_device(md, dd->dm_dev); kfree(dd); } } @@ -247,7 +248,7 @@ void dm_table_destroy(struct dm_table *t) vfree(t->highs); /* free the device list */ - free_devices(&t->devices); + free_devices(&t->devices, t->md); dm_free_md_mempools(t->mempools); @@ -262,52 +263,12 @@ static struct dm_dev_internal *find_device(struct list_head *l, dev_t dev) struct dm_dev_internal *dd; list_for_each_entry (dd, l, list) - if (dd->dm_dev.bdev->bd_dev == dev) + if (dd->dm_dev->bdev->bd_dev == dev) return dd; return NULL; } -/* - * Open a device so we can use it as a map destination. - */ -static int open_dev(struct dm_dev_internal *d, dev_t dev, - struct mapped_device *md) -{ - static char *_claim_ptr = "I belong to device-mapper"; - struct block_device *bdev; - - int r; - - BUG_ON(d->dm_dev.bdev); - - bdev = blkdev_get_by_dev(dev, d->dm_dev.mode | FMODE_EXCL, _claim_ptr); - if (IS_ERR(bdev)) - return PTR_ERR(bdev); - - r = bd_link_disk_holder(bdev, dm_disk(md)); - if (r) { - blkdev_put(bdev, d->dm_dev.mode | FMODE_EXCL); - return r; - } - - d->dm_dev.bdev = bdev; - return 0; -} - -/* - * Close a device that we've been using. - */ -static void close_dev(struct dm_dev_internal *d, struct mapped_device *md) -{ - if (!d->dm_dev.bdev) - return; - - bd_unlink_disk_holder(d->dm_dev.bdev, dm_disk(md)); - blkdev_put(d->dm_dev.bdev, d->dm_dev.mode | FMODE_EXCL); - d->dm_dev.bdev = NULL; -} - /* * If possible, this checks an area of a destination device is invalid. */ @@ -386,19 +347,17 @@ static int upgrade_mode(struct dm_dev_internal *dd, fmode_t new_mode, struct mapped_device *md) { int r; - struct dm_dev_internal dd_new, dd_old; + struct dm_dev *old_dev, *new_dev; - dd_new = dd_old = *dd; + old_dev = dd->dm_dev; - dd_new.dm_dev.mode |= new_mode; - dd_new.dm_dev.bdev = NULL; - - r = open_dev(&dd_new, dd->dm_dev.bdev->bd_dev, md); + r = dm_get_table_device(md, dd->dm_dev->bdev->bd_dev, + dd->dm_dev->mode | new_mode, &new_dev); if (r) return r; - dd->dm_dev.mode |= new_mode; - close_dev(&dd_old, md); + dd->dm_dev = new_dev; + dm_put_table_device(md, old_dev); return 0; } @@ -440,27 +399,22 @@ int dm_get_device(struct dm_target *ti, const char *path, fmode_t mode, if (!dd) return -ENOMEM; - dd->dm_dev.mode = mode; - dd->dm_dev.bdev = NULL; - - if ((r = open_dev(dd, dev, t->md))) { + if ((r = dm_get_table_device(t->md, dev, mode, &dd->dm_dev))) { kfree(dd); return r; } - format_dev_t(dd->dm_dev.name, dev); - atomic_set(&dd->count, 0); list_add(&dd->list, &t->devices); - } else if (dd->dm_dev.mode != (mode | dd->dm_dev.mode)) { + } else if (dd->dm_dev->mode != (mode | dd->dm_dev->mode)) { r = upgrade_mode(dd, mode, t->md); if (r) return r; } atomic_inc(&dd->count); - *result = &dd->dm_dev; + *result = dd->dm_dev; return 0; } EXPORT_SYMBOL(dm_get_device); @@ -505,11 +459,23 @@ static int dm_set_device_limits(struct dm_target *ti, struct dm_dev *dev, */ void dm_put_device(struct dm_target *ti, struct dm_dev *d) { - struct dm_dev_internal *dd = container_of(d, struct dm_dev_internal, - dm_dev); + int found = 0; + struct list_head *devices = &ti->table->devices; + struct dm_dev_internal *dd; + list_for_each_entry(dd, devices, list) { + if (dd->dm_dev == d) { + found = 1; + break; + } + } + if (!found) { + DMWARN("%s: device %s not in table devices list", + dm_device_name(ti->table->md), d->name); + return; + } if (atomic_dec_and_test(&dd->count)) { - close_dev(dd, ti->table->md); + dm_put_table_device(ti->table->md, d); list_del(&dd->list); kfree(dd); } @@ -906,7 +872,7 @@ static int dm_table_set_type(struct dm_table *t) /* Non-request-stackable devices can't be used for request-based dm */ devices = dm_table_get_devices(t); list_for_each_entry(dd, devices, list) { - if (!blk_queue_stackable(bdev_get_queue(dd->dm_dev.bdev))) { + if (!blk_queue_stackable(bdev_get_queue(dd->dm_dev->bdev))) { DMWARN("table load rejected: including" " non-request-stackable devices"); return -EINVAL; @@ -1043,7 +1009,7 @@ static struct gendisk * dm_table_get_integrity_disk(struct dm_table *t, struct gendisk *prev_disk = NULL, *template_disk = NULL; list_for_each_entry(dd, devices, list) { - template_disk = dd->dm_dev.bdev->bd_disk; + template_disk = dd->dm_dev->bdev->bd_disk; if (!blk_get_integrity(template_disk)) goto no_integrity; if (!match_all && !blk_integrity_is_initialized(template_disk)) @@ -1629,7 +1595,7 @@ int dm_table_any_congested(struct dm_table *t, int bdi_bits) int r = 0; list_for_each_entry(dd, devices, list) { - struct request_queue *q = bdev_get_queue(dd->dm_dev.bdev); + struct request_queue *q = bdev_get_queue(dd->dm_dev->bdev); char b[BDEVNAME_SIZE]; if (likely(q)) @@ -1637,7 +1603,7 @@ int dm_table_any_congested(struct dm_table *t, int bdi_bits) else DMWARN_LIMIT("%s: any_congested: nonexistent device %s", dm_device_name(t->md), - bdevname(dd->dm_dev.bdev, b)); + bdevname(dd->dm_dev->bdev, b)); } list_for_each_entry(cb, &t->target_callbacks, list) diff --git a/drivers/md/dm.c b/drivers/md/dm.c index 56a2c74c9a3f..58f3927fd7cc 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -142,6 +142,9 @@ struct mapped_device { */ struct dm_table *map; + struct list_head table_devices; + struct mutex table_devices_lock; + unsigned long flags; struct request_queue *queue; @@ -212,6 +215,12 @@ struct dm_md_mempools { struct bio_set *bs; }; +struct table_device { + struct list_head list; + atomic_t count; + struct dm_dev dm_dev; +}; + #define RESERVED_BIO_BASED_IOS 16 #define RESERVED_REQUEST_BASED_IOS 256 #define RESERVED_MAX_IOS 1024 @@ -669,6 +678,120 @@ static void dm_put_live_table_fast(struct mapped_device *md) __releases(RCU) rcu_read_unlock(); } +/* + * Open a table device so we can use it as a map destination. + */ +static int open_table_device(struct table_device *td, dev_t dev, + struct mapped_device *md) +{ + static char *_claim_ptr = "I belong to device-mapper"; + struct block_device *bdev; + + int r; + + BUG_ON(td->dm_dev.bdev); + + bdev = blkdev_get_by_dev(dev, td->dm_dev.mode | FMODE_EXCL, _claim_ptr); + if (IS_ERR(bdev)) + return PTR_ERR(bdev); + + r = bd_link_disk_holder(bdev, dm_disk(md)); + if (r) { + blkdev_put(bdev, td->dm_dev.mode | FMODE_EXCL); + return r; + } + + td->dm_dev.bdev = bdev; + return 0; +} + +/* + * Close a table device that we've been using. + */ +static void close_table_device(struct table_device *td, struct mapped_device *md) +{ + if (!td->dm_dev.bdev) + return; + + bd_unlink_disk_holder(td->dm_dev.bdev, dm_disk(md)); + blkdev_put(td->dm_dev.bdev, td->dm_dev.mode | FMODE_EXCL); + td->dm_dev.bdev = NULL; +} + +static struct table_device *find_table_device(struct list_head *l, dev_t dev, + fmode_t mode) { + struct table_device *td; + + list_for_each_entry(td, l, list) + if (td->dm_dev.bdev->bd_dev == dev && td->dm_dev.mode == mode) + return td; + + return NULL; +} + +int dm_get_table_device(struct mapped_device *md, dev_t dev, fmode_t mode, + struct dm_dev **result) { + int r; + struct table_device *td; + + mutex_lock(&md->table_devices_lock); + td = find_table_device(&md->table_devices, dev, mode); + if (!td) { + td = kmalloc(sizeof(*td), GFP_KERNEL); + if (!td) { + mutex_unlock(&md->table_devices_lock); + return -ENOMEM; + } + + td->dm_dev.mode = mode; + td->dm_dev.bdev = NULL; + + if ((r = open_table_device(td, dev, md))) { + mutex_unlock(&md->table_devices_lock); + kfree(td); + return r; + } + + format_dev_t(td->dm_dev.name, dev); + + atomic_set(&td->count, 0); + list_add(&td->list, &md->table_devices); + } + atomic_inc(&td->count); + mutex_unlock(&md->table_devices_lock); + + *result = &td->dm_dev; + return 0; +} +EXPORT_SYMBOL_GPL(dm_get_table_device); + +void dm_put_table_device(struct mapped_device *md, struct dm_dev *d) +{ + struct table_device *td = container_of(d, struct table_device, dm_dev); + + mutex_lock(&md->table_devices_lock); + if (atomic_dec_and_test(&td->count)) { + close_table_device(td, md); + list_del(&td->list); + kfree(td); + } + mutex_unlock(&md->table_devices_lock); +} +EXPORT_SYMBOL(dm_put_table_device); + +static void free_table_devices(struct list_head *devices) +{ + struct list_head *tmp, *next; + + list_for_each_safe(tmp, next, devices) { + struct table_device *td = list_entry(tmp, struct table_device, list); + + DMWARN("dm_destroy: %s still exists with %d references", + td->dm_dev.name, atomic_read(&td->count)); + kfree(td); + } +} + /* * Get the geometry associated with a dm device */ @@ -1944,12 +2067,14 @@ static struct mapped_device *alloc_dev(int minor) md->type = DM_TYPE_NONE; mutex_init(&md->suspend_lock); mutex_init(&md->type_lock); + mutex_init(&md->table_devices_lock); spin_lock_init(&md->deferred_lock); atomic_set(&md->holders, 1); atomic_set(&md->open_count, 0); atomic_set(&md->event_nr, 0); atomic_set(&md->uevent_seq, 0); INIT_LIST_HEAD(&md->uevent_list); + INIT_LIST_HEAD(&md->table_devices); spin_lock_init(&md->uevent_lock); md->queue = blk_alloc_queue(GFP_KERNEL); @@ -2035,6 +2160,7 @@ static void free_dev(struct mapped_device *md) blk_integrity_unregister(md->disk); del_gendisk(md->disk); cleanup_srcu_struct(&md->io_barrier); + free_table_devices(&md->table_devices); free_minor(minor); spin_lock(&_minor_lock); diff --git a/drivers/md/dm.h b/drivers/md/dm.h index e81d2152fa68..988c7fb7b145 100644 --- a/drivers/md/dm.h +++ b/drivers/md/dm.h @@ -44,7 +44,7 @@ struct dm_dev_internal { struct list_head list; atomic_t count; - struct dm_dev dm_dev; + struct dm_dev *dm_dev; }; struct dm_table; @@ -188,6 +188,9 @@ int dm_cancel_deferred_remove(struct mapped_device *md); int dm_request_based(struct mapped_device *md); sector_t dm_get_size(struct mapped_device *md); struct request_queue *dm_get_md_queue(struct mapped_device *md); +int dm_get_table_device(struct mapped_device *md, dev_t dev, fmode_t mode, + struct dm_dev **result); +void dm_put_table_device(struct mapped_device *md, struct dm_dev *d); struct dm_stats *dm_get_stats(struct mapped_device *md); int dm_kobject_uevent(struct mapped_device *md, enum kobject_action action, diff --git a/include/uapi/linux/dm-ioctl.h b/include/uapi/linux/dm-ioctl.h index c8a4302093a3..3315ab21f728 100644 --- a/include/uapi/linux/dm-ioctl.h +++ b/include/uapi/linux/dm-ioctl.h @@ -267,9 +267,9 @@ enum { #define DM_DEV_SET_GEOMETRY _IOWR(DM_IOCTL, DM_DEV_SET_GEOMETRY_CMD, struct dm_ioctl) #define DM_VERSION_MAJOR 4 -#define DM_VERSION_MINOR 27 +#define DM_VERSION_MINOR 28 #define DM_VERSION_PATCHLEVEL 0 -#define DM_VERSION_EXTRA "-ioctl (2013-10-30)" +#define DM_VERSION_EXTRA "-ioctl (2014-09-17)" /* Status bits */ #define DM_READONLY_FLAG (1 << 0) /* In/Out */ -- 2.20.1