From 26803b9f06d365122fae82e7554a66ef8278e0bb Mon Sep 17 00:00:00 2001 From: Will Drewry Date: Thu, 12 Aug 2010 04:14:03 +0100 Subject: dm ioctl: refactor dm_table_complete This change unifies the various checks and finalization that occurs on a table prior to use. By doing so, it allows table construction without traversing the dm-ioctl interface. Signed-off-by: Will Drewry Signed-off-by: Alasdair G Kergon --- drivers/md/dm-table.c | 55 ++++++++++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 52 insertions(+), 3 deletions(-) (limited to 'drivers/md/dm-table.c') diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c index 9924ea23032d..bc60ef77a0d8 100644 --- a/drivers/md/dm-table.c +++ b/drivers/md/dm-table.c @@ -245,7 +245,7 @@ void dm_table_destroy(struct dm_table *t) msleep(1); smp_mb(); - /* free the indexes (see dm_table_complete) */ + /* free the indexes */ if (t->depth >= 2) vfree(t->index[t->depth - 2]); @@ -778,7 +778,7 @@ int dm_table_add_target(struct dm_table *t, const char *type, return r; } -int dm_table_set_type(struct dm_table *t) +static int dm_table_set_type(struct dm_table *t) { unsigned i; unsigned bio_based = 0, request_based = 0; @@ -900,7 +900,7 @@ static int setup_indexes(struct dm_table *t) /* * Builds the btree to index the map. */ -int dm_table_complete(struct dm_table *t) +static int dm_table_build_index(struct dm_table *t) { int r = 0; unsigned int leaf_nodes; @@ -919,6 +919,55 @@ int dm_table_complete(struct dm_table *t) return r; } +/* + * Register the mapped device for blk_integrity support if + * the underlying devices support it. + */ +static int dm_table_prealloc_integrity(struct dm_table *t, struct mapped_device *md) +{ + struct list_head *devices = dm_table_get_devices(t); + struct dm_dev_internal *dd; + + list_for_each_entry(dd, devices, list) + if (bdev_get_integrity(dd->dm_dev.bdev)) + return blk_integrity_register(dm_disk(md), NULL); + + return 0; +} + +/* + * Prepares the table for use by building the indices, + * setting the type, and allocating mempools. + */ +int dm_table_complete(struct dm_table *t) +{ + int r; + + r = dm_table_set_type(t); + if (r) { + DMERR("unable to set table type"); + return r; + } + + r = dm_table_build_index(t); + if (r) { + DMERR("unable to build btrees"); + return r; + } + + r = dm_table_prealloc_integrity(t, t->md); + if (r) { + DMERR("could not register integrity profile."); + return r; + } + + r = dm_table_alloc_md_mempools(t); + if (r) + DMERR("unable to allocate mempools"); + + return r; +} + static DEFINE_MUTEX(_event_lock); void dm_table_event_callback(struct dm_table *t, void (*fn)(void *), void *context) -- cgit From 5ae89a8720c28caf35c4e53711d77df2856c404e Mon Sep 17 00:00:00 2001 From: Mike Snitzer Date: Thu, 12 Aug 2010 04:14:08 +0100 Subject: dm: linear support discard Allow discards to be passed through to linear mappings if at least one underlying device supports it. Discards will be forwarded only to devices that support them. A target that supports discards should set num_discard_requests to indicate how many times each discard request must be submitted to it. Verify table's underlying devices support discards prior to setting the associated DM device as capable of discards (via QUEUE_FLAG_DISCARD). Signed-off-by: Mike Snitzer Signed-off-by: Mikulas Patocka Reviewed-by: Joe Thornber Signed-off-by: Alasdair G Kergon --- drivers/md/dm-table.c | 44 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 44 insertions(+) (limited to 'drivers/md/dm-table.c') diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c index bc60ef77a0d8..f9fc07d7a4b9 100644 --- a/drivers/md/dm-table.c +++ b/drivers/md/dm-table.c @@ -54,6 +54,8 @@ struct dm_table { sector_t *highs; struct dm_target *targets; + unsigned discards_supported:1; + /* * Indicates the rw permissions for the new logical * device. This should be a combination of FMODE_READ @@ -203,6 +205,7 @@ int dm_table_create(struct dm_table **result, fmode_t mode, INIT_LIST_HEAD(&t->devices); atomic_set(&t->holders, 0); + t->discards_supported = 1; if (!num_targets) num_targets = KEYS_PER_NODE; @@ -770,6 +773,9 @@ int dm_table_add_target(struct dm_table *t, const char *type, t->highs[t->num_targets++] = tgt->begin + tgt->len - 1; + if (!tgt->num_discard_requests) + t->discards_supported = 0; + return 0; bad: @@ -1135,6 +1141,11 @@ void dm_table_set_restrictions(struct dm_table *t, struct request_queue *q, else queue_flag_set_unlocked(QUEUE_FLAG_CLUSTER, q); + if (!dm_table_supports_discards(t)) + queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, q); + else + queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, q); + dm_table_set_integrity(t); /* @@ -1281,6 +1292,39 @@ struct mapped_device *dm_table_get_md(struct dm_table *t) return t->md; } +static int device_discard_capable(struct dm_target *ti, struct dm_dev *dev, + sector_t start, sector_t len, void *data) +{ + struct request_queue *q = bdev_get_queue(dev->bdev); + + return q && blk_queue_discard(q); +} + +bool dm_table_supports_discards(struct dm_table *t) +{ + struct dm_target *ti; + unsigned i = 0; + + if (!t->discards_supported) + return 0; + + /* + * Ensure that at least one underlying device supports discards. + * t->devices includes internal dm devices such as mirror logs + * so we need to use iterate_devices here, which targets + * supporting discard must provide. + */ + while (i < dm_table_get_num_targets(t)) { + ti = dm_table_get_target(t, i++); + + if (ti->type->iterate_devices && + ti->type->iterate_devices(ti, device_discard_capable, NULL)) + return 1; + } + + return 0; +} + EXPORT_SYMBOL(dm_vcalloc); EXPORT_SYMBOL(dm_get_device); EXPORT_SYMBOL(dm_put_device); -- cgit From c8bf1336824ebd698d37b71763e1c43190f2229a Mon Sep 17 00:00:00 2001 From: "Martin K. Petersen" Date: Fri, 10 Sep 2010 20:07:38 +0200 Subject: Consolidate min_not_zero We have several users of min_not_zero, each of them using their own definition. Move the define to kernel.h. Signed-off-by: Martin K. Petersen Signed-off-by: Jens Axboe --- drivers/md/dm-table.c | 5 ----- 1 file changed, 5 deletions(-) (limited to 'drivers/md/dm-table.c') diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c index f9fc07d7a4b9..90267f8d64ee 100644 --- a/drivers/md/dm-table.c +++ b/drivers/md/dm-table.c @@ -486,11 +486,6 @@ static int __table_get_device(struct dm_table *t, struct dm_target *ti, return 0; } -/* - * Returns the minimum that is _not_ zero, unless both are zero. - */ -#define min_not_zero(l, r) (l == 0) ? r : ((r == 0) ? l : min(l, r)) - int dm_set_device_limits(struct dm_target *ti, struct dm_dev *dev, sector_t start, sector_t len, void *data) { -- cgit From e09b457bdb7e8d23fc54dcef0930ac697d8de895 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Sat, 13 Nov 2010 11:55:17 +0100 Subject: block: simplify holder symlink handling Code to manage symlinks in /sys/block/*/{holders|slaves} are overly complex with multiple holder considerations, redundant extra references to all involved kobjects, unused generic kobject holder support and unnecessary mixup with bd_claim/release functionalities. Strip it down to what's necessary (single gendisk holder) and make it use a separate interface. This is a step for cleaning up bd_claim/release. This patch makes dm-table slightly more complex but it will be simplified again with further changes. Signed-off-by: Tejun Heo Acked-by: Neil Brown Acked-by: Mike Snitzer Cc: dm-devel@redhat.com --- drivers/md/dm-table.c | 23 +++++++++++++++++------ 1 file changed, 17 insertions(+), 6 deletions(-) (limited to 'drivers/md/dm-table.c') diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c index 90267f8d64ee..2c876ffc63df 100644 --- a/drivers/md/dm-table.c +++ b/drivers/md/dm-table.c @@ -328,12 +328,22 @@ static int open_dev(struct dm_dev_internal *d, dev_t dev, bdev = open_by_devnum(dev, d->dm_dev.mode); if (IS_ERR(bdev)) return PTR_ERR(bdev); - r = bd_claim_by_disk(bdev, _claim_ptr, dm_disk(md)); - if (r) + + r = bd_claim(bdev, _claim_ptr); + if (r) { blkdev_put(bdev, d->dm_dev.mode); - else - d->dm_dev.bdev = bdev; - return r; + return r; + } + + r = bd_link_disk_holder(bdev, dm_disk(md)); + if (r) { + bd_release(bdev); + blkdev_put(bdev, d->dm_dev.mode); + return r; + } + + d->dm_dev.bdev = bdev; + return 0; } /* @@ -344,7 +354,8 @@ static void close_dev(struct dm_dev_internal *d, struct mapped_device *md) if (!d->dm_dev.bdev) return; - bd_release_from_disk(d->dm_dev.bdev, dm_disk(md)); + bd_unlink_disk_holder(d->dm_dev.bdev); + bd_release(d->dm_dev.bdev); blkdev_put(d->dm_dev.bdev, d->dm_dev.mode); d->dm_dev.bdev = NULL; } -- cgit From e525fd89d380c4a94c0d63913a1dd1a593ed25e7 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Sat, 13 Nov 2010 11:55:17 +0100 Subject: block: make blkdev_get/put() handle exclusive access Over time, block layer has accumulated a set of APIs dealing with bdev open, close, claim and release. * blkdev_get/put() are the primary open and close functions. * bd_claim/release() deal with exclusive open. * open/close_bdev_exclusive() are combination of open and claim and the other way around, respectively. * bd_link/unlink_disk_holder() to create and remove holder/slave symlinks. * open_by_devnum() wraps bdget() + blkdev_get(). The interface is a bit confusing and the decoupling of open and claim makes it impossible to properly guarantee exclusive access as in-kernel open + claim sequence can disturb the existing exclusive open even before the block layer knows the current open if for another exclusive access. Reorganize the interface such that, * blkdev_get() is extended to include exclusive access management. @holder argument is added and, if is @FMODE_EXCL specified, it will gain exclusive access atomically w.r.t. other exclusive accesses. * blkdev_put() is similarly extended. It now takes @mode argument and if @FMODE_EXCL is set, it releases an exclusive access. Also, when the last exclusive claim is released, the holder/slave symlinks are removed automatically. * bd_claim/release() and close_bdev_exclusive() are no longer necessary and either made static or removed. * bd_link_disk_holder() remains the same but bd_unlink_disk_holder() is no longer necessary and removed. * open_bdev_exclusive() becomes a simple wrapper around lookup_bdev() and blkdev_get(). It also has an unexpected extra bdev_read_only() test which probably should be moved into blkdev_get(). * open_by_devnum() is modified to take @holder argument and pass it to blkdev_get(). Most of bdev open/close operations are unified into blkdev_get/put() and most exclusive accesses are tested atomically at the open time (as it should). This cleans up code and removes some, both valid and invalid, but unnecessary all the same, corner cases. open_bdev_exclusive() and open_by_devnum() can use further cleanup - rename to blkdev_get_by_path() and blkdev_get_by_devt() and drop special features. Well, let's leave them for another day. Most conversions are straight-forward. drbd conversion is a bit more involved as there was some reordering, but the logic should stay the same. Signed-off-by: Tejun Heo Acked-by: Neil Brown Acked-by: Ryusuke Konishi Acked-by: Mike Snitzer Acked-by: Philipp Reisner Cc: Peter Osterlund Cc: Martin Schwidefsky Cc: Heiko Carstens Cc: Jan Kara Cc: Andrew Morton Cc: Andreas Dilger Cc: "Theodore Ts'o" Cc: Mark Fasheh Cc: Joel Becker Cc: Alex Elder Cc: Christoph Hellwig Cc: dm-devel@redhat.com Cc: drbd-dev@lists.linbit.com Cc: Leo Chen Cc: Scott Branden Cc: Chris Mason Cc: Steven Whitehouse Cc: Dave Kleikamp Cc: Joern Engel Cc: reiserfs-devel@vger.kernel.org Cc: Alexander Viro --- drivers/md/dm-table.c | 15 +++------------ 1 file changed, 3 insertions(+), 12 deletions(-) (limited to 'drivers/md/dm-table.c') diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c index 2c876ffc63df..9e88ca0c55e9 100644 --- a/drivers/md/dm-table.c +++ b/drivers/md/dm-table.c @@ -325,20 +325,13 @@ static int open_dev(struct dm_dev_internal *d, dev_t dev, BUG_ON(d->dm_dev.bdev); - bdev = open_by_devnum(dev, d->dm_dev.mode); + bdev = open_by_devnum(dev, d->dm_dev.mode | FMODE_EXCL, _claim_ptr); if (IS_ERR(bdev)) return PTR_ERR(bdev); - r = bd_claim(bdev, _claim_ptr); - if (r) { - blkdev_put(bdev, d->dm_dev.mode); - return r; - } - r = bd_link_disk_holder(bdev, dm_disk(md)); if (r) { - bd_release(bdev); - blkdev_put(bdev, d->dm_dev.mode); + blkdev_put(bdev, d->dm_dev.mode | FMODE_EXCL); return r; } @@ -354,9 +347,7 @@ 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); - bd_release(d->dm_dev.bdev); - blkdev_put(d->dm_dev.bdev, d->dm_dev.mode); + blkdev_put(d->dm_dev.bdev, d->dm_dev.mode | FMODE_EXCL); d->dm_dev.bdev = NULL; } -- cgit From d4d77629953eabd3c14f6fa5746f6b28babfc55f Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Sat, 13 Nov 2010 11:55:18 +0100 Subject: block: clean up blkdev_get() wrappers and their users After recent blkdev_get() modifications, open_by_devnum() and open_bdev_exclusive() are simple wrappers around blkdev_get(). Replace them with blkdev_get_by_dev() and blkdev_get_by_path(). blkdev_get_by_dev() is identical to open_by_devnum(). blkdev_get_by_path() is slightly different in that it doesn't automatically add %FMODE_EXCL to @mode. All users are converted. Most conversions are mechanical and don't introduce any behavior difference. There are several exceptions. * btrfs now sets FMODE_EXCL in btrfs_device->mode, so there's no reason to OR it explicitly on blkdev_put(). * gfs2, nilfs2 and the generic mount_bdev() now set FMODE_EXCL in sb->s_mode. * With the above changes, sb->s_mode now always should contain FMODE_EXCL. WARN_ON_ONCE() added to kill_block_super() to detect errors. The new blkdev_get_*() functions are with proper docbook comments. While at it, add function description to blkdev_get() too. Signed-off-by: Tejun Heo Cc: Philipp Reisner Cc: Neil Brown Cc: Mike Snitzer Cc: Joern Engel Cc: Chris Mason Cc: Jan Kara Cc: "Theodore Ts'o" Cc: KONISHI Ryusuke Cc: reiserfs-devel@vger.kernel.org Cc: xfs-masters@oss.sgi.com Cc: Alexander Viro --- drivers/md/dm-table.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/md/dm-table.c') diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c index 9e88ca0c55e9..67150c32986c 100644 --- a/drivers/md/dm-table.c +++ b/drivers/md/dm-table.c @@ -325,7 +325,7 @@ static int open_dev(struct dm_dev_internal *d, dev_t dev, BUG_ON(d->dm_dev.bdev); - bdev = open_by_devnum(dev, d->dm_dev.mode | FMODE_EXCL, _claim_ptr); + bdev = blkdev_get_by_dev(dev, d->dm_dev.mode | FMODE_EXCL, _claim_ptr); if (IS_ERR(bdev)) return PTR_ERR(bdev); -- cgit From e692cb668fdd5a712c6ed2a2d6f2a36ee83997b4 Mon Sep 17 00:00:00 2001 From: "Martin K. Petersen" Date: Wed, 1 Dec 2010 19:41:49 +0100 Subject: block: Deprecate QUEUE_FLAG_CLUSTER and use queue_limits instead When stacking devices, a request_queue is not always available. This forced us to have a no_cluster flag in the queue_limits that could be used as a carrier until the request_queue had been set up for a metadevice. There were several problems with that approach. First of all it was up to the stacking device to remember to set queue flag after stacking had completed. Also, the queue flag and the queue limits had to be kept in sync at all times. We got that wrong, which could lead to us issuing commands that went beyond the max scatterlist limit set by the driver. The proper fix is to avoid having two flags for tracking the same thing. We deprecate QUEUE_FLAG_CLUSTER and use the queue limit directly in the block layer merging functions. The queue_limit 'no_cluster' is turned into 'cluster' to avoid double negatives and to ease stacking. Clustering defaults to being enabled as before. The queue flag logic is removed from the stacking function, and explicitly setting the cluster flag is no longer necessary in DM and MD. Reported-by: Ed Lin Signed-off-by: Martin K. Petersen Acked-by: Mike Snitzer Cc: stable@kernel.org Signed-off-by: Jens Axboe --- drivers/md/dm-table.c | 5 ----- 1 file changed, 5 deletions(-) (limited to 'drivers/md/dm-table.c') diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c index 90267f8d64ee..e2da1912a2cb 100644 --- a/drivers/md/dm-table.c +++ b/drivers/md/dm-table.c @@ -1131,11 +1131,6 @@ void dm_table_set_restrictions(struct dm_table *t, struct request_queue *q, */ q->limits = *limits; - if (limits->no_cluster) - queue_flag_clear_unlocked(QUEUE_FLAG_CLUSTER, q); - else - queue_flag_set_unlocked(QUEUE_FLAG_CLUSTER, q); - if (!dm_table_supports_discards(t)) queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, q); else -- cgit From 72d4cd9f38b5ed96b75df4c622be25e1c2648dd3 Mon Sep 17 00:00:00 2001 From: Mike Snitzer Date: Fri, 17 Dec 2010 08:34:20 +0100 Subject: block: max hardware sectors limit wrapper Implement blk_limits_max_hw_sectors() and make blk_queue_max_hw_sectors() a wrapper around it. DM needs this to avoid setting queue_limits' max_hw_sectors and max_sectors directly. dm_set_device_limits() now leverages blk_limits_max_hw_sectors() logic to establish the appropriate max_hw_sectors minimum (PAGE_SIZE). Fixes issue where DM was incorrectly setting max_sectors rather than max_hw_sectors (which caused dm_merge_bvec()'s max_hw_sectors check to be ineffective). Signed-off-by: Mike Snitzer Cc: stable@kernel.org Acked-by: Martin K. Petersen Signed-off-by: Jens Axboe --- drivers/md/dm-table.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) (limited to 'drivers/md/dm-table.c') diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c index e2da1912a2cb..4d705cea0f8c 100644 --- a/drivers/md/dm-table.c +++ b/drivers/md/dm-table.c @@ -517,9 +517,8 @@ int dm_set_device_limits(struct dm_target *ti, struct dm_dev *dev, */ if (q->merge_bvec_fn && !ti->type->merge) - limits->max_sectors = - min_not_zero(limits->max_sectors, - (unsigned int) (PAGE_SIZE >> 9)); + blk_limits_max_hw_sectors(limits, + (unsigned int) (PAGE_SIZE >> 9)); return 0; } EXPORT_SYMBOL_GPL(dm_set_device_limits); -- cgit From 9d357b0787bb3c91835d5e658c3bda178f9ca419 Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Thu, 13 Jan 2011 20:00:01 +0000 Subject: dm: introduce target callbacks and congestion callback DM currently implements congestion checking by checking on congestion in each component device. For raid456 we need to also check if the stripe cache is congested. Add per-target congestion checker callback support. Extending the target_callbacks structure with additional callback functions allows for establishing multiple callbacks per-target (a callback is also needed for unplug). Cc: linux-raid@vger.kernel.org Signed-off-by: NeilBrown Signed-off-by: Jonathan Brassow Signed-off-by: Mike Snitzer Signed-off-by: Alasdair G Kergon --- drivers/md/dm-table.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) (limited to 'drivers/md/dm-table.c') diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c index 985c20a4f30e..7e2ec3c05550 100644 --- a/drivers/md/dm-table.c +++ b/drivers/md/dm-table.c @@ -71,6 +71,8 @@ struct dm_table { void *event_context; struct dm_md_mempools *mempools; + + struct list_head target_callbacks; }; /* @@ -204,6 +206,7 @@ int dm_table_create(struct dm_table **result, fmode_t mode, return -ENOMEM; INIT_LIST_HEAD(&t->devices); + INIT_LIST_HEAD(&t->target_callbacks); atomic_set(&t->holders, 0); t->discards_supported = 1; @@ -1225,10 +1228,17 @@ int dm_table_resume_targets(struct dm_table *t) return 0; } +void dm_table_add_target_callbacks(struct dm_table *t, struct dm_target_callbacks *cb) +{ + list_add(&cb->list, &t->target_callbacks); +} +EXPORT_SYMBOL_GPL(dm_table_add_target_callbacks); + int dm_table_any_congested(struct dm_table *t, int bdi_bits) { struct dm_dev_internal *dd; struct list_head *devices = dm_table_get_devices(t); + struct dm_target_callbacks *cb; int r = 0; list_for_each_entry(dd, devices, list) { @@ -1243,6 +1253,10 @@ int dm_table_any_congested(struct dm_table *t, int bdi_bits) bdevname(dd->dm_dev.bdev, b)); } + list_for_each_entry(cb, &t->target_callbacks, list) + if (cb->congested_fn) + r |= cb->congested_fn(cb, bdi_bits); + return r; } -- cgit From 99d03c141b40914b67d63c9d23b8da4386422ed7 Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Thu, 13 Jan 2011 20:00:02 +0000 Subject: dm: per target unplug callback support Add per-target unplug callback support. Cc: linux-raid@vger.kernel.org Signed-off-by: NeilBrown Signed-off-by: Jonathan Brassow Signed-off-by: Mike Snitzer Signed-off-by: Alasdair G Kergon --- drivers/md/dm-table.c | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'drivers/md/dm-table.c') diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c index 7e2ec3c05550..dffa0ac7c4f0 100644 --- a/drivers/md/dm-table.c +++ b/drivers/md/dm-table.c @@ -1278,6 +1278,7 @@ void dm_table_unplug_all(struct dm_table *t) { struct dm_dev_internal *dd; struct list_head *devices = dm_table_get_devices(t); + struct dm_target_callbacks *cb; list_for_each_entry(dd, devices, list) { struct request_queue *q = bdev_get_queue(dd->dm_dev.bdev); @@ -1290,6 +1291,10 @@ void dm_table_unplug_all(struct dm_table *t) dm_device_name(t->md), bdevname(dd->dm_dev.bdev, b)); } + + list_for_each_entry(cb, &t->target_callbacks, list) + if (cb->unplug_fn) + cb->unplug_fn(cb); } struct mapped_device *dm_table_get_md(struct dm_table *t) -- cgit From 49731baa41df404c2c3f44555869ab387363af43 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Fri, 14 Jan 2011 18:43:57 +0100 Subject: block: restore multiple bd_link_disk_holder() support Commit e09b457b (block: simplify holder symlink handling) incorrectly assumed that there is only one link at maximum. dm may use multiple links and expects block layer to track reference count for each link, which is different from and unrelated to the exclusive device holder identified by @holder when the device is opened. Remove the single holder assumption and automatic removal of the link and revive the per-link reference count tracking. The code essentially behaves the same as before commit e09b457b sans the unnecessary kobject reference count dancing. While at it, note that this facility should not be used by anyone else than the current ones. Sysfs symlinks shouldn't be abused like this and the whole thing doesn't belong in the block layer at all. Signed-off-by: Tejun Heo Reported-by: Milan Broz Cc: Jun'ichi Nomura Cc: Neil Brown Cc: linux-raid@vger.kernel.org Cc: Kay Sievers Signed-off-by: Jens Axboe --- drivers/md/dm-table.c | 1 + 1 file changed, 1 insertion(+) (limited to 'drivers/md/dm-table.c') diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c index dffa0ac7c4f0..38e4eb1bb965 100644 --- a/drivers/md/dm-table.c +++ b/drivers/md/dm-table.c @@ -350,6 +350,7 @@ 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; } -- cgit