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* block: add queue flag for SSD/non-rotational devicesJens Axboe2008-10-092-0/+12
| | | | | | | | | We don't want to idle in AS/CFQ if the device doesn't have a seek penalty. So add a QUEUE_FLAG_NONROT to indicate a non-rotational device, low level drivers should set this flag upon discovery of an SSD or similar device type. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* block: add a queue flag for request stacking supportKiyoshi Ueda2008-10-091-1/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch adds a queue flag to indicate the block device can be used for request stacking. Request stacking drivers need to stack their devices on top of only devices of which q->request_fn is functional. Since bio stacking drivers (e.g. md, loop) basically initialize their queue using blk_alloc_queue() and don't set q->request_fn, the check of (q->request_fn == NULL) looks enough for that purpose. However, dm will become both types of stacking driver (bio-based and request-based). And dm will always set q->request_fn even if the dm device is bio-based of which q->request_fn is not functional actually. So we need something else to distinguish the type of the device. Adding a queue flag is a solution for that. The reason why dm always sets q->request_fn is to keep the compatibility of dm user-space tools. Currently, all dm user-space tools are using bio-based dm without specifying the type of the dm device they use. To use request-based dm without changing such tools, the kernel must decide the type of the dm device automatically. The automatic type decision can't be done at the device creation time and needs to be deferred until such tools load a mapping table, since the actual type is decided by dm target type included in the mapping table. So a dm device has to be initialized using blk_init_queue() so that we can load either type of table. Then, all queue stuffs are set (e.g. q->request_fn) and we have no element to distinguish that it is bio-based or request-based, even after a table is loaded and the type of the device is decided. By the way, some stuffs of the queue (e.g. request_list, elevator) are needless when the dm device is used as bio-based. But the memory size is not so large (about 20[KB] per queue on ia64), so I hope the memory loss can be acceptable for bio-based dm users. Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com> Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* block: add request submission interfaceKiyoshi Ueda2008-10-091-0/+81
| | | | | | | | | | | | | | | | | | This patch adds blk_insert_cloned_request(), a generic request submission interface for request stacking drivers. Request-based dm will use it to submit their clones to underlying devices. blk_rq_check_limits() is also added because it is possible that the lower queue has stronger limitations than the upper queue if multiple drivers are stacking at request-level. Not only for blk_insert_cloned_request()'s internal use, the function will be used by request-based dm when the queue limitation is modified (e.g. by replacing dm's table). Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com> Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* block: add request update interfaceKiyoshi Ueda2008-10-091-9/+48
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch adds blk_update_request(), which updates struct request with completing its data part, but doesn't complete the struct request itself. Though it looks like end_that_request_first() of older kernels, blk_update_request() should be used only by request stacking drivers. Request-based dm will use it in bio->bi_end_io callback to update the original request when a data part of a cloned request completes. Followings are additional background information of why request-based dm needs this interface. - Request stacking drivers can't use blk_end_request() directly from the lower driver's completion context (bio->bi_end_io or rq->end_io), because some device drivers (e.g. ide) may try to complete their request with queue lock held, and it may cause deadlock. See below for detailed description of possible deadlock: <http://marc.info/?l=linux-kernel&m=120311479108569&w=2> - To solve that, request-based dm offloads the completion of cloned struct request to softirq context (i.e. using blk_complete_request() from rq->end_io). - Though it is possible to use the same solution from bio->bi_end_io, it will delay the notification of bio completion to the original submitter. Also, it will cause inefficient partial completion, because the lower driver can't perform the cloned request anymore and request-based dm needs to requeue and redispatch it to the lower driver again later. That's not good. - So request-based dm needs blk_update_request() to perform the bio completion in the lower driver's completion context, which is more efficient. Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com> Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* block: blk_cleanup_queue() should call blk_sync_queue()Jens Axboe2008-10-091-0/+8
| | | | | | | | | When a driver calls blk_cleanup_queue(), the device should be fully idle. However, the block layer may have pending plugging timers and the IO schedulers may have pending work in the work queues. So quisce the device by waiting for the timer and flushing the work queues. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* block: use rq complete marking in blk_abort_request()Jens Axboe2008-10-091-0/+2
| | | | | | | | | | We cannot abort a request if we raced with the timeout handler already, or with the IO completion. So make blk_abort_request() mark the request as complete, and only continue if we succeeded. Found and suggested by Mike Anderson <andmike@linux.vnet.ibm.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* block: add fault injection mechanism for faking request timeoutsJens Axboe2008-10-094-0/+81
| | | | | | | | Only works for the generic request timer handling. Allows one to sporadically ignore request completions, thus exercising the timeout handling. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* block: adjust blkdev_issue_discard for swapHugh Dickins2008-10-091-3/+4
| | | | | | | | | | | | | | | | Two mods to blkdev_issue_discard(), thinking ahead to its use on swap: 1. Add gfp_mask argument, so swap allocation can use it where GFP_KERNEL might deadlock but GFP_NOIO is safe. 2. Enlarge nr_sects argument from unsigned to sector_t: unsigned long is enough to cover a whole swap area, but sector_t suits any partition. Change sb_issue_discard()'s nr_blocks to sector_t too; but no need seen for a gfp_mask there, just pass GFP_KERNEL down to blkdev_issue_discard(). Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* block: Add interface to abort queued requestsMike Anderson2008-10-092-0/+35
| | | | | Signed-off-by: Mike Anderson <andmike@linux.vnet.ibm.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* block: unify request timeout handlingJens Axboe2008-10-097-14/+226
| | | | | | | | | | | | | Right now SCSI and others do their own command timeout handling. Move those bits to the block layer. Instead of having a timer per command, we try to be a bit more clever and simply have one per-queue. This avoids the overhead of having to tear down and setup a timer for each command, so it will result in a lot less timer fiddling. Signed-off-by: Mike Anderson <andmike@linux.vnet.ibm.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* block: fix duplicate headers for /proc/partitionsTejun Heo2008-10-091-1/+1
| | | | | | | | seqf can be started multiple times for a read and the header should be printed only for the initial one. Fix it. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* block: make blk_rq_map_user take a NULL user-space bufferFUJITA Tomonori2008-10-091-4/+12
| | | | | | | | | | | This patch changes blk_rq_map_user to accept a NULL user-space buffer with a READ command if rq_map_data is not NULL. Thus a caller can pass page frames to lk_rq_map_user to just set up a request and bios with page frames propely. bio_uncopy_user (called via blk_rq_unmap_user) doesn't copy data to user space with such request. Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* block: update comment on end_request()Jens Axboe2008-10-091-3/+3
| | | | | | | It refers to functions that no longer exist after the IO completion changes. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* block: don't test for partition size in bdget_disk() and blk_lookup_devt()Tejun Heo2008-10-091-2/+2
| | | | | | | | | | | | | | | | | bdget_disk() and blk_lookup_devt() never cared whether the specified partition (or disk) is zero sized or not. I got confused while converting those not to depend on consecutive minor numbers in commit 5a6411b1178baf534aa9138052864dfa89d3eada and later when dev0 was added it broke callers which expected to get valid return for zero sized disk devices. So, they never needed nr_sects checks in the first place. Kill them. This problem was spotted and debugged by Bartlmoiej Zolnierkiewicz. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* block: kmalloc args reversed, small function definition fixesHarvey Harrison2008-10-092-3/+3
| | | | | | | | | | | | | | | | Noticed by sparse: block/blk-softirq.c:156:12: warning: symbol 'blk_softirq_init' was not declared. Should it be static? block/genhd.c:583:28: warning: function 'bdget_disk' with external linkage has definition block/genhd.c:659:17: warning: incorrect type in argument 1 (different base types) block/genhd.c:659:17: expected unsigned int [unsigned] [usertype] size block/genhd.c:659:17: got restricted gfp_t block/genhd.c:659:29: warning: incorrect type in argument 2 (different base types) block/genhd.c:659:29: expected restricted gfp_t [usertype] flags block/genhd.c:659:29: got unsigned int block: kmalloc args reversed Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* block: add blk_rq_aligned helper functionFUJITA Tomonori2008-10-091-10/+2
| | | | | | | | | | This adds blk_rq_aligned helper function to see if alignment and padding requirement is satisfied for DMA transfer. This also converts blk_rq_map_kern and __blk_rq_map_user to use the helper function. Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> Cc: Jens Axboe <jens.axboe@oracle.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* block: introduce struct rq_map_data to use reserved pagesFUJITA Tomonori2008-10-093-15/+22
| | | | | | | | | | | | | | | | | | | | This patch introduces struct rq_map_data to enable bio_copy_use_iov() use reserved pages. Currently, bio_copy_user_iov allocates bounce pages but drivers/scsi/sg.c wants to allocate pages by itself and use them. struct rq_map_data can be used to pass allocated pages to bio_copy_user_iov. The current users of bio_copy_user_iov simply passes NULL (they don't want to use pre-allocated pages). Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> Cc: Jens Axboe <jens.axboe@oracle.com> Cc: Douglas Gilbert <dougg@torque.net> Cc: Mike Christie <michaelc@cs.wisc.edu> Cc: James Bottomley <James.Bottomley@HansenPartnership.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* block: add gfp_mask argument to blk_rq_map_user and blk_rq_map_user_iovFUJITA Tomonori2008-10-093-12/+18
| | | | | | | | | | | | | | Currently, blk_rq_map_user and blk_rq_map_user_iov always do GFP_KERNEL allocation. This adds gfp_mask argument to blk_rq_map_user and blk_rq_map_user_iov so sg can use it (sg always does GFP_ATOMIC allocation). Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> Signed-off-by: Douglas Gilbert <dougg@torque.net> Cc: Mike Christie <michaelc@cs.wisc.edu> Cc: James Bottomley <James.Bottomley@HansenPartnership.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* cfq-iosched: fix queue depth detectionAaron Carroll2008-10-091-9/+38
| | | | | | | | | | | | | | CFQ's detection of queueing devices assumes a non-queuing device and detects if the queue depth reaches a certain threshold. Under some workloads (e.g. synchronous reads), CFQ effectively forces a unit queue depth, thus defeating the detection logic. This leads to poor performance on queuing hardware, since the idle window remains enabled. This patch inverts the sense of the logic: assume a queuing-capable device, and detect if the depth does not exceed the threshold. Signed-off-by: Aaron Carroll <aaronc@gelato.unsw.edu.au> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* block: don't use bio_has_data() in the completion pathJens Axboe2008-10-091-3/+2
| | | | | | | | We should just check for rq->bio, as that is really the information we are looking for. Even if the bio attached doesn't carry data, we still need to do IO post processing on it. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* block: inherit CPU completion on bio->rq and rq->rq mergesJens Axboe2008-10-092-0/+6
| | | | | | | | | Somewhat incomplete, as we do allow merges of requests and bios that have different completion CPUs given. This is done on the assumption that a larger IO is still more beneficial than CPU locality. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* block: add support for IO CPU affinityJens Axboe2008-10-095-55/+162
| | | | | | | | | | | | | | | | | | This patch adds support for controlling the IO completion CPU of either all requests on a queue, or on a per-request basis. We export a sysfs variable (rq_affinity) which, if set, migrates completions of requests to the CPU that originally submitted it. A bio helper (bio_set_completion_cpu()) is also added, so that queuers can ask for completion on that specific CPU. In testing, this has been show to cut the system time by as much as 20-40% on synthetic workloads where CPU affinity is desired. This requires a little help from the architecture, so it'll only work as designed for archs that are using the new generic smp helper infrastructure. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* block: make kblockd_schedule_work() take the queue as parameterJens Axboe2008-10-093-8/+8
| | | | | | Preparatory patch for checking queuing affinity. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* block: split softirq handling into blk-softirq.cJens Axboe2008-10-093-90/+105
| | | | Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* block: use linux/uaccess.h in elevator.c instead of asm variantJens Axboe2008-10-091-2/+1
| | | | Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* block: allow disk to have extended device numberTejun Heo2008-10-091-1/+24
| | | | | | | | | | | | | | | | | | | | | Now that disk and partition handlings are mostly unified, it's easy to allow disk to have extended device number. This patch makes add_disk() use extended device number if disk->minors is zero. Both sd and ide-disk are updated to use this. * sd_format_disk_name() is implemented which can generically determine the drive name. This removes disk number restriction stemming from limited device names. * If sd index goes over SD_MAX_DISKS (which can be increased now BTW), sd simply doesn't initialize minors letting block layer choose extended device number. * If CONFIG_DEBUG_EXT_DEVT is set, both sd and ide-disk always set minors to 0 and use extended device numbers. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* block: replace @ext_minors with GENHD_FL_EXT_DEVTTejun Heo2008-10-091-15/+1
| | | | | | | | | | | | | | | With previous changes, it's meaningless to limit the number of partitions. Replace @ext_minors with GENHD_FL_EXT_DEVT such that setting the flag allows the disk to have maximum number of allowed partitions (only limited by the number of entries in parsed_partitions as determined by MAX_PART constant). This kills not-too-pretty alloc_disk_ext[_node]() functions and makes @minors parameter to alloc_disk[_node]() unnecessary. The parameter is left alone to avoid disturbing the users. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* block: make partition array dynamicTejun Heo2008-10-092-21/+110
| | | | | | | | | | | | disk->__part used to be statically allocated to the maximum possible number of partitions. This patch makes partition array allocation dynamic. The added overhead is minimal as only real change is one memory dereference changed to RCU one. This saves both a bit of memory and cpu cycles iterating through unoccupied slots and makes increasing partition limit easier. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* block: move stats from disk to part0Tejun Heo2008-10-093-131/+62
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Move stats related fields - stamp, in_flight, dkstats - from disk to part0 and unify stat handling such that... * part_stat_*() now updates part0 together if the specified partition is not part0. ie. part_stat_*() are now essentially all_stat_*(). * {disk|all}_stat_*() are gone. * part_round_stats() is updated similary. It handles part0 stats automatically and disk_round_stats() is killed. * part_{inc|dec}_in_fligh() is implemented which automatically updates part0 stats for parts other than part0. * disk_map_sector_rcu() is updated to return part0 if no part matches. Combined with the above changes, this makes NULL special case handling in callers unnecessary. * Separate stats show code paths for disk are collapsed into part stats show code paths. * Rename disk_stat_lock/unlock() to part_stat_lock/unlock() While at it, reposition stat handling macros a bit and add missing parentheses around macro parameters. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* block: kill GENHD_FL_FAIL and use part0->make_it_failTejun Heo2008-10-092-31/+4
| | | | | | | | GENHD_FL_FAIL for disk is what make_it_fail is for parts. Kill it and use part0->make_it_fail. Sysfs node handling is unified too. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* block: always set bdev->bd_partTejun Heo2008-10-091-1/+1
| | | | | | | | | Till now, bdev->bd_part is set only if the bdev was for parts other than part0. This patch makes bdev->bd_part always set so that code paths don't have to differenciate common handling. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* block: move holder_dir from disk to part0Tejun Heo2008-10-091-7/+2
| | | | | | | | | | | | | Move disk->holder_dir to part0->holder_dir. Kill now mostly superflous bdev_get_holder(). While at it, kill superflous kobject_get/put() around holder_dir, slave_dir and cmd_filter creation and collapse disk_sysfs_add_subdirs() into register_disk(). These serve no purpose but obfuscating the code. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* block: move policy from disk to part0Tejun Heo2008-10-091-11/+5
| | | | | | | Move disk->policy to part0->policy. Implement and use get_disk_ro(). Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* block: unify sysfs size node handlingTejun Heo2008-10-091-9/+1
| | | | | | | | Now that capacity and __dev are moved to part0, part0 and others can share the same method. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* block: move __dev from disk to part0Tejun Heo2008-10-091-28/+12
| | | | | | | | | | | | | | | Move disk->__dev to part0->__dev. This simplifies bdget_disk() and lookup_devt() and allows common sysfs attributes to be unified. part_to_disk() is updated to handle part0 -> disk. Updated to include a fix from Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>, he writes: "part0 is a "special" partition and doesn't need to have capacity set - this fixes regression caused by "block: move __dev from disk to part0" commit." Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* block: introduce partition 0Tejun Heo2008-10-092-19/+25
| | | | | | | | | | | | | | | | | | | | | | | genhd and partition code handled disk and partitions separately. All information about the whole disk was in struct genhd and partitions in struct hd_struct. However, the whole disk (part0) and other partitions have a lot in common and the data structures end up having good number of common fields and thus separate code paths doing the same thing. Also, the partition array was indexed by partno - 1 which gets pretty confusing at times. This patch introduces partition 0 and makes the partition array indexed by partno. Following patches will unify the handling of disk and parts piece-by-piece. This patch also implements disk_partitionable() which tests whether a disk is partitionable. With coming dynamic partition array change, the most common usage of disk_max_parts() will be testing whether a disk is partitionable and the number of max partitions will become much less important. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* block: implement and use {disk|part}_to_dev()Tejun Heo2008-10-093-17/+19
| | | | | | | | | | | | Implement {disk|part}_to_dev() and use them to access generic device instead of directly dereferencing {disk|part}->dev. To make sure no user is left behind, rename generic devices fields to __dev. This is in preparation of unifying partition 0 handling with other partitions. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* block: implement CONFIG_DEBUG_BLOCK_EXT_DEVTTejun Heo2008-10-091-3/+35
| | | | | | | | | | | | | | | | Extended devt introduces non-contiguos device numbers. This patch implements a debug option which forces most devt allocations to be from the extended area and spreads them out. This is enabled by default if DEBUG_KERNEL is set and achieves... 1. Detects code paths in kernel or userland which expect predetermined consecutive device numbers. 2. When something goes wrong, avoid corruption as adding to the minor of earlier partition won't lead to the wrong but valid device. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* block: adjust formatting for large minors and add ext_range sysfs attrTejun Heo2008-10-091-11/+34
| | | | | | | | | | | | | | | | | | | | With extended minors and the soon-to-follow debug feature, large minor numbers for block devices will be common. This patch does the followings to make printouts pretty. * Adapt print formats such that large minors don't break the formatting. * For extended MAJ:MIN, %02x%02x for MAJ:MIN used in printk_all_partitions() doesn't cut it anymore. Update it such that %03x:%05x is used if either MAJ or MIN doesn't fit in %02x. * Implement ext_range sysfs attribute which shows total minors the device can use including both conventional minor space and the extended one. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* block: implement extended dev numbersTejun Heo2008-10-091-5/+115
| | | | | | | | | | | | | | | | | | | | Implement extended device numbers. A block driver can tell block layer that it wants to use extended device numbers. After the usual minor space is used up, block layer automatically allocates devt's from EXT_BLOCK_MAJOR. Currently only one major number is allocated for this but as the allocation is strictly on-demand, ~1mil minor space under it should suffice unless the system actually has more than ~1mil partitions and if that ever happens adding more majors to the extended devt area is easy. Due to internal implementation issues, the first partition can't be allocated on the extended area. In other words, genhd->minors should at least be 1. This limitation will be lifted by later changes. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* block: fix diskstats accessTejun Heo2008-10-093-39/+44
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | There are two variants of stat functions - ones prefixed with double underbars which don't care about preemption and ones without which disable preemption before manipulating per-cpu counters. It's unclear whether the underbarred ones assume that preemtion is disabled on entry as some callers don't do that. This patch unifies diskstats access by implementing disk_stat_lock() and disk_stat_unlock() which take care of both RCU (for partition access) and preemption (for per-cpu counter access). diskstats access should always be enclosed between the two functions. As such, there's no need for the versions which disables preemption. They're removed and double underbars ones are renamed to drop the underbars. As an extra argument is added, there's no danger of using the old version unconverted. disk_stat_lock() uses get_cpu() and returns the cpu index and all diskstat functions which access per-cpu counters now has @cpu argument to help RT. This change adds RCU or preemption operations at some places but also collapses several preemption ops into one at others. Overall, the performance difference should be negligible as all involved ops are very lightweight per-cpu ones. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* block: fix disk->part[] dereferencing raceTejun Heo2008-10-094-47/+226
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | disk->part[] is protected by its matching bdev's lock. However, non-critical accesses like collecting stats and printing out sysfs and proc information used to be performed without any locking. As partitions can come and go dynamically, partitions can go away underneath those non-critical accesses. As some of those accesses are writes, this theoretically can lead to silent corruption. This patch fixes the race by using RCU for the partition array and dev reference counter to hold partitions. * Rename disk->part[] to disk->__part[] to make sure no one outside genhd layer proper accesses it directly. * Use RCU for disk->__part[] dereferencing. * Implement disk_{get|put}_part() which can be used to get and put partitions from gendisk respectively. * Iterators are implemented to help iterate through all partitions safely. * Functions which require RCU readlock are marked with _rcu suffix. * Use disk_put_part() in __blkdev_put() instead of directly putting the contained kobject. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* block: don't depend on consecutive minor spaceTejun Heo2008-10-092-34/+79
| | | | | | | | | | | | | | | | | | | | | | | | | | * Implement disk_devt() and part_devt() and use them to directly access devt instead of computing it from ->major and ->first_minor. Note that all references to ->major and ->first_minor outside of block layer is used to determine devt of the disk (the part0) and as ->major and ->first_minor will continue to represent devt for the disk, converting these users aren't strictly necessary. However, convert them for consistency. * Implement disk_max_parts() to avoid directly deferencing genhd->minors. * Update bdget_disk() such that it doesn't assume consecutive minor space. * Move devt computation from register_disk() to add_disk() and make it the only one (all other usages use the initially determined value). These changes clean up the code and will help disk->part dereference fix and extended block device numbers. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* block: make variable and argument names more consistentTejun Heo2008-10-092-36/+33
| | | | | | | | | | | | | | In hd_struct, @partno is used to denote partition number and a number of other places use @part to denote hd_struct. Functions use @part and @index instead. This causes confusion and makes it difficult to use consistent variable names for hd_struct. Always use @partno if a variable represents partition number. Also, print out functions use @f or @part for seq_file argument. Use @seqf uniformly instead. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* block: misc updatesTejun Heo2008-10-093-7/+8
| | | | | | | | | | | | | | | | | This patch makes the following misc updates in preparation for disk->part dereference fix and extended block devt support. * implment part_to_disk() * fix comment about gendisk->part indexing * rename get_part() to disk_map_sector() * don't use n which is always zero while printing disk information in diskstats_show() Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* block: update add_partition() error handlingTejun Heo2008-10-091-5/+2
| | | | | | | | | | | | | | | | | | | | | | | | d805dda4 tried to fix error case handling in add_partition() but had a few problems. * disk->part[] entry is set early and left dangling if operation fails. * Once device initialized, the last put_device() is responsible for freeing all the resources. The failure path freed part_stats and p regardless of put_device() causing double free. * holders subdir holds reference to the disk device, so failure path should remove it to release resources properly which was missing. This patch fixes the above problems and while at it move partition slot busy check into add_partition() for completeness and inlines holders subdirectory creation. Using separate function for it just obfuscates the code. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Abdel Benamrouche <draconux@gmail.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* block: allow deleting zero length partitionTejun Heo2008-10-091-2/+0
| | | | | | | | | | | | | | delete_partition() was noop for zero length partition. As the addition code allows creating zero lenght partition and deletion is assumed to always succeed, this causes memory leak for zero length partitions. Allow zero length partitions to end their meaningless lives. While at it, allow deleting zero lenght partition via BLKPG_DEL_PARTITION ioctl too. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* block: use class_dev_iterator instead of class_for_each_device()Tejun Heo2008-10-091-155/+97
| | | | | | | | | | | | | | | | | | | Recent block_class iteration updates 5c6f35c5..27f3025 converted all class device iteration to class_for_each_device() and class_find_device(), which are correct but pain in the ass to use. This pach converts them to newly introduced class_dev_iterator so that they can use more natural control structures instead of separate callbacks and struct to pass parameters to them. This results in smaller and easier code. This patch also restores the original behavior of not printing header in /proc/partitions if there's no partition to print. This is trivial but still user-visible behavior. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* block: don't grab block_class_lock unnecessarilyTejun Heo2008-10-091-19/+9
| | | | | | | | | block_class_lock protects major_names array and bdev_map and doesn't have anything to do with block class devices. Don't grab them while iterating over block class devices. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* block: fix partition info printoutsTejun Heo2008-10-091-5/+5
| | | | | | | | | | | | | | | | | | | | | Recent block_class iteration updates 5c6f35c5..27f3025 broke partition info printouts. * printk_all_partitions(): Partition print out stops when it meets a partition hole. Partition printing inner loop should continue instead of exiting on empty partition slot. * /proc/partitions and /proc/diskstats: If all information can't be read in single read(), the information is truncated. This is because find_start() doesn't actually update the counter containing the initial seek. It runs to the end and ends up always reporting EOF on the second read. This patch fixes both problems. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
generated by cgit v1.2.3 (git 2.25.1) at 2024-12-24 12:07:22 +0000