aboutsummaryrefslogtreecommitdiffstats
path: root/block/blk-sysfs.c (follow)
AgeCommit message (Collapse)AuthorFilesLines
2022-03-24Merge tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsiLinus Torvalds1-2/+1
Pull SCSI updates from James Bottomley: "This series consists of the usual driver updates (qla2xxx, pm8001, libsas, smartpqi, scsi_debug, lpfc, iscsi, mpi3mr) plus minor updates and bug fixes. The high blast radius core update is the removal of write same, which affects block and several non-SCSI devices. The other big change, which is more local, is the removal of the SCSI pointer" * tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi: (281 commits) scsi: scsi_ioctl: Drop needless assignment in sg_io() scsi: bsg: Drop needless assignment in scsi_bsg_sg_io_fn() scsi: lpfc: Copyright updates for 14.2.0.0 patches scsi: lpfc: Update lpfc version to 14.2.0.0 scsi: lpfc: SLI path split: Refactor BSG paths scsi: lpfc: SLI path split: Refactor Abort paths scsi: lpfc: SLI path split: Refactor SCSI paths scsi: lpfc: SLI path split: Refactor CT paths scsi: lpfc: SLI path split: Refactor misc ELS paths scsi: lpfc: SLI path split: Refactor VMID paths scsi: lpfc: SLI path split: Refactor FDISC paths scsi: lpfc: SLI path split: Refactor LS_RJT paths scsi: lpfc: SLI path split: Refactor LS_ACC paths scsi: lpfc: SLI path split: Refactor the RSCN/SCR/RDF/EDC/FARPR paths scsi: lpfc: SLI path split: Refactor PLOGI/PRLI/ADISC/LOGO paths scsi: lpfc: SLI path split: Refactor base ELS paths and the FLOGI path scsi: lpfc: SLI path split: Introduce lpfc_prep_wqe scsi: lpfc: SLI path split: Refactor fast and slow paths to native SLI4 scsi: lpfc: SLI path split: Refactor lpfc_iocbq scsi: lpfc: Use kcalloc() ...
2022-03-08block: move blk_exit_queue into disk_releaseMing Lei1-16/+0
There can't be file system I/O in disk_release(), so move the call to blk_exit_queue() there, preparing to have the teardown of file system I/O only functionality in one place, when the gendisk that is needed for it is torn down. We still need to freeze queue here since the request is freed after the bio is completed and passthrough request rely on scheduler tags as well. The disk can be released before or after queue is cleaned up, and we have to free the scheduler request pool before blk_cleanup_queue returns, while the static request pool has to be freed before exiting the I/O scheduler. Signed-off-by: Ming Lei <ming.lei@redhat.com> [hch: rebased, updated the commit log] Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Link: https://lore.kernel.org/r/20220308055200.735835-13-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-03-08block: move q_usage_counter release into blk_queue_releaseMing Lei1-0/+2
After blk_cleanup_queue() returns, disk may not be released yet, so probably bio may still be submitted and ->q_usage_counter may be touched, so far this way seems safe, but not good from API's viewpoint. Move the release q_usage_counter into blk_queue_release(). Signed-off-by: Ming Lei <ming.lei@redhat.com> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20220308055200.735835-12-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-03-08block: move blkcg initialization/destroy into disk allocation/release handlerMing Lei1-7/+0
blkcg works on FS bio level, so it is reasonable to make both blkcg and gendisk sharing same lifetime. Meantime there won't be any FS IO when releasing disk, so safe to move blkcg initialization/destroy into disk allocation/release handler Long term, we can move blkcg into gendisk completely. Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com> Link: https://lore.kernel.org/r/20220308055200.735835-10-hch@lst.de [axboe: fixup missing blk-cgroup.h include] Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-02-28blk-crypto: show crypto capabilities in sysfsEric Biggers1-0/+6
Add sysfs files that expose the inline encryption capabilities of request queues: /sys/block/$disk/queue/crypto/max_dun_bits /sys/block/$disk/queue/crypto/modes/$mode /sys/block/$disk/queue/crypto/num_keyslots Userspace can use these new files to decide what encryption settings to use, or whether to use inline encryption at all. This also brings the crypto capabilities in line with the other queue properties, which are already discoverable via the queue directory in sysfs. Design notes: - Place the new files in a new subdirectory "crypto" to group them together and to avoid complicating the main "queue" directory. This also makes it possible to replace "crypto" with a symlink later if we ever make the blk_crypto_profiles into real kobjects (see below). - It was necessary to define a new kobject that corresponds to the crypto subdirectory. For now, this kobject just contains a pointer to the blk_crypto_profile. Note that multiple queues (and hence multiple such kobjects) may refer to the same blk_crypto_profile. An alternative design would more closely match the current kernel data structures: the blk_crypto_profile could be a kobject itself, located directly under the host controller device's kobject, while /sys/block/$disk/queue/crypto would be a symlink to it. I decided not to do that for now because it would require a lot more changes, such as no longer embedding blk_crypto_profile in other structures, and also because I'm not sure we can rule out moving the crypto capabilities into 'struct queue_limits' in the future. (Even if multiple queues share the same crypto engine, maybe the supported data unit sizes could differ due to other queue properties.) It would also still be possible to switch to that design later without breaking userspace, by replacing the directory with a symlink. - Use "max_dun_bits" instead of "max_dun_bytes". Currently, the kernel internally stores this value in bytes, but that's an implementation detail. It probably makes more sense to talk about this value in bits, and choosing bits is more future-proof. - "modes" is a sub-subdirectory, since there may be multiple supported crypto modes, sysfs is supposed to have one value per file, and it makes sense to group all the mode files together. - Each mode had to be named. The crypto API names like "xts(aes)" are not appropriate because they don't specify the key size. Therefore, I assigned new names. The exact names chosen are arbitrary, but they happen to match the names used in log messages in fs/crypto/. - The "num_keyslots" file is a bit different from the others in that it is only useful to know for performance reasons. However, it's included as it can still be useful. For example, a user might not want to use inline encryption if there aren't very many keyslots. Reviewed-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Eric Biggers <ebiggers@google.com> Link: https://lore.kernel.org/r/20220124215938.2769-4-ebiggers@kernel.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-02-28block: don't delete queue kobject before its childrenEric Biggers1-3/+5
kobjects aren't supposed to be deleted before their child kobjects are deleted. Apparently this is usually benign; however, a WARN will be triggered if one of the child kobjects has a named attribute group: sysfs group 'modes' not found for kobject 'crypto' WARNING: CPU: 0 PID: 1 at fs/sysfs/group.c:278 sysfs_remove_group+0x72/0x80 ... Call Trace: sysfs_remove_groups+0x29/0x40 fs/sysfs/group.c:312 __kobject_del+0x20/0x80 lib/kobject.c:611 kobject_cleanup+0xa4/0x140 lib/kobject.c:696 kobject_release lib/kobject.c:736 [inline] kref_put include/linux/kref.h:65 [inline] kobject_put+0x53/0x70 lib/kobject.c:753 blk_crypto_sysfs_unregister+0x10/0x20 block/blk-crypto-sysfs.c:159 blk_unregister_queue+0xb0/0x110 block/blk-sysfs.c:962 del_gendisk+0x117/0x250 block/genhd.c:610 Fix this by moving the kobject_del() and the corresponding kobject_uevent() to the correct place. Fixes: 2c2086afc2b8 ("block: Protect less code with sysfs_lock in blk_{un,}register_queue()") Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Eric Biggers <ebiggers@google.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20220124215938.2769-3-ebiggers@kernel.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-02-28block: simplify calling convention of elv_unregister_queue()Eric Biggers1-2/+1
Make elv_unregister_queue() a no-op if q->elevator is NULL or is not registered. This simplifies the existing callers, as well as the future caller in the error path of blk_register_queue(). Also don't bother checking whether q is NULL, since it never is. Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Eric Biggers <ebiggers@google.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20220124215938.2769-2-ebiggers@kernel.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-02-22scsi: block: Remove REQ_OP_WRITE_SAME supportChristoph Hellwig1-2/+1
No more users of REQ_OP_WRITE_SAME or drivers implementing it are left, so remove the infrastructure. [mkp: fold in and tweak sysfs reporting fix] Link: https://lore.kernel.org/r/20220209082828.2629273-8-hch@lst.de Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2022-02-11block: partition include/linux/blk-cgroup.hMing Lei1-1/+1
Partition include/linux/blk-cgroup.h into two parts: one is public part, the other is block layer private part. Suggested by Christoph Hellwig. Signed-off-by: Ming Lei <ming.lei@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20220211101149.2368042-4-ming.lei@redhat.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-01-17block: cleanup q->srcuMing Lei1-0/+3
srcu structure has to be cleanup via cleanup_srcu_struct(), so fix it. Reported-by: syzbot+4f789823c1abc5accf13@syzkaller.appspotmail.com Fixes: 704b914f15fb ("blk-mq: move srcu from blk_mq_hw_ctx to request_queue") Signed-off-by: Ming Lei <ming.lei@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20220111123401.520192-1-ming.lei@redhat.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-01-17block: Remove unnecessary variable assignmentGuoYong Zheng1-1/+0
The parameter "ret" should be zero when running to this line, no need to set to zero again, remove it. Signed-off-by: GuoYong Zheng <zhenggy@chinatelecom.cn> Link: https://lore.kernel.org/r/1642414957-6785-1-git-send-email-zhenggy@chinatelecom.cn Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-12-20block: call blk_exit_queue() before freeing q->statsMing Lei1-2/+2
blk_stat_disable_accounting() is added in commit 68497092bde9 ("block: make queue stat accounting a reference"), and called in kyber_exit_sched(). So we have to free q->stats after elevator is unloaded from blk_exit_queue() in blk_release_queue(). Otherwise kernel panic is caused. Fixes: 68497092bde9 ("block: make queue stat accounting a reference") Signed-off-by: Ming Lei <ming.lei@redhat.com> Link: https://lore.kernel.org/r/20211221040436.1333880-1-ming.lei@redhat.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-12-03blk-mq: move srcu from blk_mq_hw_ctx to request_queueMing Lei1-1/+2
In case of BLK_MQ_F_BLOCKING, per-hctx srcu is used to protect dispatch critical area. However, this srcu instance stays at the end of hctx, and it often takes standalone cacheline, often cold. Inside srcu_read_lock() and srcu_read_unlock(), WRITE is always done on the indirect percpu variable which is allocated from heap instead of being embedded, srcu->srcu_idx is read only in srcu_read_lock(). It doesn't matter if srcu structure stays in hctx or request queue. So switch to per-request-queue srcu for protecting dispatch, and this way simplifies quiesce a lot, not mention quiesce is always done on the request queue wide. Signed-off-by: Ming Lei <ming.lei@redhat.com> Link: https://lore.kernel.org/r/20211203131534.3668411-3-ming.lei@redhat.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-11-29block: don't include blk-mq-sched.h in blk.hChristoph Hellwig1-0/+1
No needed, shift it into the source files that need it instead. Signed-off-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20211123185312.1432157-5-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-11-29block: remove the e argument to elevator_exitChristoph Hellwig1-1/+1
All callers pass q->elevator. Signed-off-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20211123185312.1432157-4-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-11-29block: remove elevator_exitChristoph Hellwig1-1/+1
Open code elevator_exit in it's only caller, and rename __elevator_exit to elevator_exit. Signed-off-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20211123185312.1432157-3-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-11-29block: only allocate poll_stats if there's a user of themJens Axboe1-1/+2
This is essentially never used, yet it's about 1/3rd of the total queue size. Allocate it when needed, and don't embed it in the queue. Kill the queue flag for this while at it, since we can just check the assigned pointer now. Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-11-15blk-mq: cancel blk-mq dispatch work in both blk_cleanup_queue and disk_release()Ming Lei1-10/+0
For avoiding to slow down queue destroy, we don't call blk_mq_quiesce_queue() in blk_cleanup_queue(), instead of delaying to cancel dispatch work in blk_release_queue(). However, this way has caused kernel oops[1], reported by Changhui. The log shows that scsi_device can be freed before running blk_release_queue(), which is expected too since scsi_device is released after the scsi disk is closed and the scsi_device is removed. Fixes the issue by canceling blk-mq dispatch work in both blk_cleanup_queue() and disk_release(): 1) when disk_release() is run, the disk has been closed, and any sync dispatch activities have been done, so canceling dispatch work is enough to quiesce filesystem I/O dispatch activity. 2) in blk_cleanup_queue(), we only focus on passthrough request, and passthrough request is always explicitly allocated & freed by its caller, so once queue is frozen, all sync dispatch activity for passthrough request has been done, then it is enough to just cancel dispatch work for avoiding any dispatch activity. [1] kernel panic log [12622.769416] BUG: kernel NULL pointer dereference, address: 0000000000000300 [12622.777186] #PF: supervisor read access in kernel mode [12622.782918] #PF: error_code(0x0000) - not-present page [12622.788649] PGD 0 P4D 0 [12622.791474] Oops: 0000 [#1] PREEMPT SMP PTI [12622.796138] CPU: 10 PID: 744 Comm: kworker/10:1H Kdump: loaded Not tainted 5.15.0+ #1 [12622.804877] Hardware name: Dell Inc. PowerEdge R730/0H21J3, BIOS 1.5.4 10/002/2015 [12622.813321] Workqueue: kblockd blk_mq_run_work_fn [12622.818572] RIP: 0010:sbitmap_get+0x75/0x190 [12622.823336] Code: 85 80 00 00 00 41 8b 57 08 85 d2 0f 84 b1 00 00 00 45 31 e4 48 63 cd 48 8d 1c 49 48 c1 e3 06 49 03 5f 10 4c 8d 6b 40 83 f0 01 <48> 8b 33 44 89 f2 4c 89 ef 0f b6 c8 e8 fa f3 ff ff 83 f8 ff 75 58 [12622.844290] RSP: 0018:ffffb00a446dbd40 EFLAGS: 00010202 [12622.850120] RAX: 0000000000000001 RBX: 0000000000000300 RCX: 0000000000000004 [12622.858082] RDX: 0000000000000006 RSI: 0000000000000082 RDI: ffffa0b7a2dfe030 [12622.866042] RBP: 0000000000000004 R08: 0000000000000001 R09: ffffa0b742721334 [12622.874003] R10: 0000000000000008 R11: 0000000000000008 R12: 0000000000000000 [12622.881964] R13: 0000000000000340 R14: 0000000000000000 R15: ffffa0b7a2dfe030 [12622.889926] FS: 0000000000000000(0000) GS:ffffa0baafb40000(0000) knlGS:0000000000000000 [12622.898956] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [12622.905367] CR2: 0000000000000300 CR3: 0000000641210001 CR4: 00000000001706e0 [12622.913328] Call Trace: [12622.916055] <TASK> [12622.918394] scsi_mq_get_budget+0x1a/0x110 [12622.922969] __blk_mq_do_dispatch_sched+0x1d4/0x320 [12622.928404] ? pick_next_task_fair+0x39/0x390 [12622.933268] __blk_mq_sched_dispatch_requests+0xf4/0x140 [12622.939194] blk_mq_sched_dispatch_requests+0x30/0x60 [12622.944829] __blk_mq_run_hw_queue+0x30/0xa0 [12622.949593] process_one_work+0x1e8/0x3c0 [12622.954059] worker_thread+0x50/0x3b0 [12622.958144] ? rescuer_thread+0x370/0x370 [12622.962616] kthread+0x158/0x180 [12622.966218] ? set_kthread_struct+0x40/0x40 [12622.970884] ret_from_fork+0x22/0x30 [12622.974875] </TASK> [12622.977309] Modules linked in: scsi_debug rpcsec_gss_krb5 auth_rpcgss nfsv4 dns_resolver nfs lockd grace fscache netfs sunrpc dm_multipath intel_rapl_msr intel_rapl_common dell_wmi_descriptor sb_edac rfkill video x86_pkg_temp_thermal intel_powerclamp dcdbas coretemp kvm_intel kvm mgag200 irqbypass i2c_algo_bit rapl drm_kms_helper ipmi_ssif intel_cstate intel_uncore syscopyarea sysfillrect sysimgblt fb_sys_fops pcspkr cec mei_me lpc_ich mei ipmi_si ipmi_devintf ipmi_msghandler acpi_power_meter drm fuse xfs libcrc32c sr_mod cdrom sd_mod t10_pi sg ixgbe ahci libahci crct10dif_pclmul crc32_pclmul crc32c_intel libata megaraid_sas ghash_clmulni_intel tg3 wdat_wdt mdio dca wmi dm_mirror dm_region_hash dm_log dm_mod [last unloaded: scsi_debug] Reported-by: ChanghuiZhong <czhong@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: "Martin K. Petersen" <martin.petersen@oracle.com> Cc: Bart Van Assche <bvanassche@acm.org> Cc: linux-scsi@vger.kernel.org Signed-off-by: Ming Lei <ming.lei@redhat.com> Link: https://lore.kernel.org/r/20211116014343.610501-1-ming.lei@redhat.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-10-26block: Add independent access ranges supportDamien Le Moal1-8/+18
The Concurrent Positioning Ranges VPD page (for SCSI) and data log page (for ATA) contain parameters describing the set of contiguous LBAs that can be served independently by a single LUN multi-actuator hard-disk. Similarly, a logically defined block device composed of multiple disks can in some cases execute requests directed at different sector ranges in parallel. A dm-linear device aggregating 2 block devices together is an example. This patch implements support for exposing a block device independent access ranges to the user through sysfs to allow optimizing device accesses to increase performance. To describe the set of independent sector ranges of a device (actuators of a multi-actuator HDDs or table entries of a dm-linear device), The type struct blk_independent_access_ranges is introduced. This structure describes the sector ranges using an array of struct blk_independent_access_range structures. This range structure defines the start sector and number of sectors of the access range. The ranges in the array cannot overlap and must contain all sectors within the device capacity. The function disk_set_independent_access_ranges() allows a device driver to signal to the block layer that a device has multiple independent access ranges. In this case, a struct blk_independent_access_ranges is attached to the device request queue by the function disk_set_independent_access_ranges(). The function disk_alloc_independent_access_ranges() is provided for drivers to allocate this structure. struct blk_independent_access_ranges contains kobjects (struct kobject) to expose to the user through sysfs the set of independent access ranges supported by a device. When the device is initialized, sysfs registration of the ranges information is done from blk_register_queue() using the block layer internal function disk_register_independent_access_ranges(). If a driver calls disk_set_independent_access_ranges() for a registered queue, e.g. when a device is revalidated, disk_set_independent_access_ranges() will execute disk_register_independent_access_ranges() to update the sysfs attribute files. The sysfs file structure created starts from the independent_access_ranges sub-directory and contains the start sector and number of sectors of each range, with the information for each range grouped in numbered sub-directories. E.g. for a dual actuator HDD, the user sees: $ tree /sys/block/sdk/queue/independent_access_ranges/ /sys/block/sdk/queue/independent_access_ranges/ |-- 0 | |-- nr_sectors | `-- sector `-- 1 |-- nr_sectors `-- sector For a regular device with a single access range, the independent_access_ranges sysfs directory does not exist. Device revalidation may lead to changes to this structure and to the attribute values. When manipulated, the queue sysfs_lock and sysfs_dir_lock mutexes are held for atomicity, similarly to how the blk-mq and elevator sysfs queue sub-directories are protected. The code related to the management of independent access ranges is added in the new file block/blk-ia-ranges.c. Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Keith Busch <kbusch@kernel.org> Link: https://lore.kernel.org/r/20211027022223.183838-2-damien.lemoal@wdc.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-10-18block: don't allow writing to the poll queue attributeChristoph Hellwig1-19/+4
The poll attribute is a historic artefact from before when we had explicit poll queues that require driver specific configuration. Just print a warning when writing to the attribute. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Sagi Grimberg <sagi@grimberg.me> Tested-by: Mark Wunderlich <mark.wunderlich@intel.com> Link: https://lore.kernel.org/r/20211012111226.760968-16-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-10-18block: move blk-throtl fast path inlineJens Axboe1-0/+1
Even if no policies are defined, we spend ~2% of the total IO time checking. Move the fast path inline. Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-08-23block: call blk_register_queue earlier in device_add_diskChristoph Hellwig1-9/+0
Ensure that all the sysfs bits are set up before bdev_add is called, as that will make the upcomding error handling much easier. However this means the call to disk_update_readahead has to be split as that requires a bdi. Also remove various sanity checks that don't make sense now that blk_register_queue only has a single caller. Signed-off-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20210818144542.19305-7-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-08-23block: add an explicit ->disk backpointer to the request_queueChristoph Hellwig1-7/+6
Replace the magic lookup through the kobject tree with an explicit backpointer, given that the device model links are set up and torn down at times when I/O is still possible, leading to potential NULL or invalid pointer dereferences. Fixes: edb0872f44ec ("block: move the bdi from the request_queue to the gendisk") Reported-by: syzbot <syzbot+aa0801b6b32dca9dda82@syzkaller.appspotmail.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Tested-by: Sven Schnelle <svens@linux.ibm.com> Link: https://lore.kernel.org/r/20210816134624.GA24234@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-08-16block: unexport blk_register_queueChristoph Hellwig1-1/+0
Not actually used in any modular code. Signed-off-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20210816123649.601591-1-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-08-09block: move the bdi from the request_queue to the gendiskChristoph Hellwig1-14/+12
The backing device information only makes sense for file system I/O, and thus belongs into the gendisk and not the lower level request_queue structure. Move it there. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Link: https://lore.kernel.org/r/20210809141744.1203023-5-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-08-09block: pass a gendisk to blk_queue_update_readaheadChristoph Hellwig1-1/+1
.. and rename the function to disk_update_readahead. This is in preparation for moving the BDI from the request_queue to the gendisk. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Link: https://lore.kernel.org/r/20210809141744.1203023-3-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-16block: mark queue init done at the end of blk_register_queueMing Lei1-14/+15
Mark queue init done when everything is done well in blk_register_queue(), so that wbt_enable_default() can be run quickly without any RCU period involved since adding rq qos requires to freeze queue. Also no any side effect by delaying to mark queue init done. Reported-by: Yi Zhang <yi.zhang@redhat.com> Cc: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Ming Lei <ming.lei@redhat.com> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Yi Zhang <yi.zhang@redhat.com> Link: https://lore.kernel.org/r/20210609015822.103433-3-ming.lei@redhat.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-05-24block: remove unneeded parenthesis from blk-sysfsMax Gurtovoy1-8/+8
Align to common code conventions. Signed-off-by: Max Gurtovoy <mgurtovoy@nvidia.com> Link: https://lore.kernel.org/r/20210511155319.1885277-1-mgurtovoy@nvidia.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-04-06block: add sysfs entry for virt boundary maskMax Gurtovoy1-1/+8
This entry will expose the bio vector alignment mask for a specific block device. Signed-off-by: Max Gurtovoy <mgurtovoy@nvidia.com> Reviewed-by: Ming Lei <ming.lei@redhat.com> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Link: https://lore.kernel.org/r/20210405132012.12504-1-mgurtovoy@nvidia.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-02-22block: fix potential IO hang when turning off io_pollJeffle Xu1-2/+5
QUEUE_FLAG_POLL flag will be cleared when turning off 'io_poll', while at that moment there may be IOs stuck in hw queue uncompleted. The following polling routine won't help reap these IOs, since blk_poll() will return immediately because of cleared QUEUE_FLAG_POLL flag. Thus these IOs will hang until they finnaly time out. The hang out can be observed by 'fio --engine=io_uring iodepth=1', while turning off 'io_poll' at the same time. To fix this, freeze and flush the request queue first when turning off 'io_poll'. Signed-off-by: Jeffle Xu <jefflexu@linux.alibaba.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-02-10block: introduce zone_write_granularity limitDamien Le Moal1-0/+8
Per ZBC and ZAC specifications, host-managed SMR hard-disks mandate that all writes into sequential write required zones be aligned to the device physical block size. However, NVMe ZNS does not have this constraint and allows write operations into sequential zones to be aligned to the device logical block size. This inconsistency does not help with software portability across device types. To solve this, introduce the zone_write_granularity queue limit to indicate the alignment constraint, in bytes, of write operations into zones of a zoned block device. This new limit is exported as a read-only sysfs queue attribute and the helper blk_queue_zone_write_granularity() introduced for drivers to set this limit. The function blk_queue_set_zoned() is modified to set this new limit to the device logical block size by default. NVMe ZNS devices as well as zoned nullb devices use this default value as is. The scsi disk driver is modified to execute the blk_queue_zone_write_granularity() helper to set the zone write granularity of host-managed SMR disks to the disk physical block size. The accessor functions queue_zone_write_granularity() and bdev_zone_write_granularity() are also introduced. Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@edc.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-10-09blk-mq: move cancel of hctx->run_work to the front of blk_exit_queueYang Yang1-1/+8
blk_exit_queue will free elevator_data, while blk_mq_run_work_fn will access it. Move cancel of hctx->run_work to the front of blk_exit_queue to avoid use-after-free. Fixes: 1b97871b501f ("blk-mq: move cancel of hctx->run_work into blk_mq_hw_sysfs_release") Signed-off-by: Yang Yang <yang.yang@vivo.com> Reviewed-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-10-09block: get rid of unnecessary local variableYufen Yu1-3/+1
Since whole elevator register is protectd by sysfs_lock, we don't need extras 'has_elevator'. Just use q->elevator directly. Signed-off-by: Yufen Yu <yuyufen@huawei.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-10-09block: invoke blk_mq_exit_sched no matter whether have .exit_schedYufen Yu1-1/+0
We will register debugfs for scheduler no matter whether it have defined callback funciton .exit_sched. So, blk_mq_exit_sched() is always needed to unregister debugfs. Also, q->elevator should be set as NULL after exiting scheduler. For now, since all register scheduler have defined .exit_sched, it will not cause any actual problem. But It will be more reasonable to do this change. Signed-off-by: Yufen Yu <yuyufen@huawei.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-09-24bdi: replace BDI_CAP_STABLE_WRITES with a queue and a sb flagChristoph Hellwig1-0/+3
The BDI_CAP_STABLE_WRITES is one of the few bits of information in the backing_dev_info shared between the block drivers and the writeback code. To help untangling the dependency replace it with a queue flag and a superblock flag derived from it. This also helps with the case of e.g. a file system requiring stable writes due to its own checksumming, but not forcing it on other users of the block device like the swap code. One downside is that we an't support the stable_pages_required bdi attribute in sysfs anymore. It is replaced with a queue attribute which also is writable for easier testing. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-09-24block: lift setting the readahead size into the block layerChristoph Hellwig1-0/+2
Drivers shouldn't really mess with the readahead size, as that is a VM concept. Instead set it based on the optimal I/O size by lifting the algorithm from the md driver when registering the disk. Also set bdi->io_pages there as well by applying the same scheme based on max_sectors. To ensure the limits work well for stacking drivers a new helper is added to update the readahead limits from the block limits, which is also called from disk_stack_limits. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Mike Snitzer <snitzer@redhat.com> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Acked-by: Coly Li <colyli@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-09-08block: make QUEUE_SYSFS_BIT_FNS more usefulChristoph Hellwig1-19/+5
Switch to the naming used by the other entries so that we can use the QUEUE_RW_ENTRY helper. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-09-08block: add helper macros for queue sysfs entriesChristoph Hellwig1-190/+58
Add two helpers macros to avoid boilerplate code for the queue sysfs entries. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-07-15block: add max_active_zones to blk-sysfsNiklas Cassel1-1/+13
Add a new max_active zones definition in the sysfs documentation. This definition will be common for all devices utilizing the zoned block device support in the kernel. Export max_active_zones according to this new definition for NVMe Zoned Namespace devices, ZAC ATA devices (which are treated as SCSI devices by the kernel), and ZBC SCSI devices. Add the new max_active_zones member to struct request_queue, rather than as a queue limit, since this property cannot be split across stacking drivers. For SCSI devices, even though max active zones is not part of the ZBC/ZAC spec, export max_active_zones as 0, signifying "no limit". Signed-off-by: Niklas Cassel <niklas.cassel@wdc.com> Reviewed-by: Javier González <javier@javigon.com> Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-07-15block: add max_open_zones to blk-sysfsNiklas Cassel1-0/+15
Add a new max_open_zones definition in the sysfs documentation. This definition will be common for all devices utilizing the zoned block device support in the kernel. Export max open zones according to this new definition for NVMe Zoned Namespace devices, ZAC ATA devices (which are treated as SCSI devices by the kernel), and ZBC SCSI devices. Add the new max_open_zones member to struct request_queue, rather than as a queue limit, since this property cannot be split across stacking drivers. Signed-off-by: Niklas Cassel <niklas.cassel@wdc.com> Reviewed-by: Javier González <javier@javigon.com> Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-24block: create the request_queue debugfs_dir on registrationLuis Chamberlain1-0/+9
We were only creating the request_queue debugfs_dir only for make_request block drivers (multiqueue), but never for request-based block drivers. We did this as we were only creating non-blktrace additional debugfs files on that directory for make_request drivers. However, since blktrace *always* creates that directory anyway, we special-case the use of that directory on blktrace. Other than this being an eye-sore, this exposes request-based block drivers to the same debugfs fragile race that used to exist with make_request block drivers where if we start adding files onto that directory we can later run a race with a double removal of dentries on the directory if we don't deal with this carefully on blktrace. Instead, just simplify things by always creating the request_queue debugfs_dir on request_queue registration. Rename the mutex also to reflect the fact that this is used outside of the blktrace context. Signed-off-by: Luis Chamberlain <mcgrof@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-24block: revert back to synchronous request_queue removalLuis Chamberlain1-21/+22
Commit dc9edc44de6c ("block: Fix a blk_exit_rl() regression") merged on v4.12 moved the work behind blk_release_queue() into a workqueue after a splat floated around which indicated some work on blk_release_queue() could sleep in blk_exit_rl(). This splat would be possible when a driver called blk_put_queue() or blk_cleanup_queue() (which calls blk_put_queue() as its final call) from an atomic context. blk_put_queue() decrements the refcount for the request_queue kobject, and upon reaching 0 blk_release_queue() is called. Although blk_exit_rl() is now removed through commit db6d99523560 ("block: remove request_list code") on v5.0, we reserve the right to be able to sleep within blk_release_queue() context. The last reference for the request_queue must not be called from atomic context. *When* the last reference to the request_queue reaches 0 varies, and so let's take the opportunity to document when that is expected to happen and also document the context of the related calls as best as possible so we can avoid future issues, and with the hopes that the synchronous request_queue removal sticks. We revert back to synchronous request_queue removal because asynchronous removal creates a regression with expected userspace interaction with several drivers. An example is when removing the loopback driver, one uses ioctls from userspace to do so, but upon return and if successful, one expects the device to be removed. Likewise if one races to add another device the new one may not be added as it is still being removed. This was expected behavior before and it now fails as the device is still present and busy still. Moving to asynchronous request_queue removal could have broken many scripts which relied on the removal to have been completed if there was no error. Document this expectation as well so that this doesn't regress userspace again. Using asynchronous request_queue removal however has helped us find other bugs. In the future we can test what could break with this arrangement by enabling CONFIG_DEBUG_KOBJECT_RELEASE. While at it, update the docs with the context expectations for the request_queue / gendisk refcount decrement, and make these expectations explicit by using might_sleep(). Fixes: dc9edc44de6c ("block: Fix a blk_exit_rl() regression") Suggested-by: Nicolai Stange <nstange@suse.de> Signed-off-by: Luis Chamberlain <mcgrof@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Cc: Bart Van Assche <bvanassche@acm.org> Cc: Omar Sandoval <osandov@fb.com> Cc: Hannes Reinecke <hare@suse.com> Cc: Nicolai Stange <nstange@suse.de> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: yu kuai <yukuai3@huawei.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-05-12block: Introduce REQ_OP_ZONE_APPENDKeith Busch1-0/+13
Define REQ_OP_ZONE_APPEND to append-write sectors to a zone of a zoned block device. This is a no-merge write operation. A zone append write BIO must: * Target a zoned block device * Have a sector position indicating the start sector of the target zone * The target zone must be a sequential write zone * The BIO must not cross a zone boundary * The BIO size must not be split to ensure that a single range of LBAs is written with a single command. Implement these checks in generic_make_request_checks() using the helper function blk_check_zone_append(). To avoid write append BIO splitting, introduce the new max_zone_append_sectors queue limit attribute and ensure that a BIO size is always lower than this limit. Export this new limit through sysfs and check these limits in bio_full(). Also when a LLDD can't dispatch a request to a specific zone, it will return BLK_STS_ZONE_RESOURCE indicating this request needs to be delayed, e.g. because the zone it will be dispatched to is still write-locked. If this happens set the request aside in a local list to continue trying dispatching requests such as READ requests or a WRITE/ZONE_APPEND requests targetting other zones. This way we can still keep a high queue depth without starving other requests even if one request can't be served due to zone write-locking. Finally, make sure that the bio sector position indicates the actual write position as indicated by the device on completion. Signed-off-by: Keith Busch <kbusch@kernel.org> [ jth: added zone-append specific add_page and merge_page helpers ] Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-10-07block: Remove "dying" checks from sysfs callbacksBart Van Assche1-8/+0
Block drivers must call del_gendisk() before blk_cleanup_queue(). del_gendisk() calls kobject_del() and kobject_del() waits until any ongoing sysfs callback functions have finished. In other words, the sysfs callback functions won't be called for a queue in the dying state. Hence remove the "dying" checks from the sysfs callback functions. Cc: Christoph Hellwig <hch@infradead.org> Cc: Ming Lei <ming.lei@redhat.com> Cc: Hannes Reinecke <hare@suse.com> Cc: Johannes Thumshirn <jthumshirn@suse.de> Signed-off-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-09-27rq-qos: get rid of redundant wbt_update_limits()Yufen Yu1-1/+0
We have updated limits after calling wbt_set_min_lat(). No need to update again. Reviewed-by: Bob Liu <bob.liu@oracle.com> Signed-off-by: Yufen Yu <yuyufen@huawei.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-09-26block: don't release queue's sysfs lock during switching elevatorMing Lei1-9/+4
cecf5d87ff20 ("block: split .sysfs_lock into two locks") starts to release & acquire sysfs_lock before registering/un-registering elevator queue during switching elevator for avoiding potential deadlock from showing & storing 'queue/iosched' attributes and removing elevator's kobject. Turns out there isn't such deadlock because 'q->sysfs_lock' isn't required in .show & .store of queue/iosched's attributes, and just elevator's sysfs lock is acquired in elv_iosched_store() and elv_iosched_show(). So it is safe to hold queue's sysfs lock when registering/un-registering elevator queue. The biggest issue is that commit cecf5d87ff20 assumes that concurrent write on 'queue/scheduler' can't happen. However, this assumption isn't true, because kernfs_fop_write() only guarantees that concurrent write aren't called on the same open file, but the write could be from different open on the file. So we can't release & re-acquire queue's sysfs lock during switching elevator, otherwise use-after-free on elevator could be triggered. Fixes the issue by not releasing queue's sysfs lock during switching elevator. Fixes: cecf5d87ff20 ("block: split .sysfs_lock into two locks") Cc: Christoph Hellwig <hch@infradead.org> Cc: Hannes Reinecke <hare@suse.com> Cc: Greg KH <gregkh@linuxfoundation.org> Cc: Mike Snitzer <snitzer@redhat.com> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-09-17Merge tag 'for-5.4/block-2019-09-16' of git://git.kernel.dk/linux-blockLinus Torvalds1-19/+31
Pull block updates from Jens Axboe: - Two NVMe pull requests: - ana log parse fix from Anton - nvme quirks support for Apple devices from Ben - fix missing bio completion tracing for multipath stack devices from Hannes and Mikhail - IP TOS settings for nvme rdma and tcp transports from Israel - rq_dma_dir cleanups from Israel - tracing for Get LBA Status command from Minwoo - Some nvme-tcp cleanups from Minwoo, Potnuri and Myself - Some consolidation between the fabrics transports for handling the CAP register - reset race with ns scanning fix for fabrics (move fabrics commands to a dedicated request queue with a different lifetime from the admin request queue)." - controller reset and namespace scan races fixes - nvme discovery log change uevent support - naming improvements from Keith - multiple discovery controllers reject fix from James - some regular cleanups from various people - Series fixing (and re-fixing) null_blk debug printing and nr_devices checks (André) - A few pull requests from Song, with fixes from Andy, Guoqing, Guilherme, Neil, Nigel, and Yufen. - REQ_OP_ZONE_RESET_ALL support (Chaitanya) - Bio merge handling unification (Christoph) - Pick default elevator correctly for devices with special needs (Damien) - Block stats fixes (Hou) - Timeout and support devices nbd fixes (Mike) - Series fixing races around elevator switching and device add/remove (Ming) - sed-opal cleanups (Revanth) - Per device weight support for BFQ (Fam) - Support for blk-iocost, a new model that can properly account cost of IO workloads. (Tejun) - blk-cgroup writeback fixes (Tejun) - paride queue init fixes (zhengbin) - blk_set_runtime_active() cleanup (Stanley) - Block segment mapping optimizations (Bart) - lightnvm fixes (Hans/Minwoo/YueHaibing) - Various little fixes and cleanups * tag 'for-5.4/block-2019-09-16' of git://git.kernel.dk/linux-block: (186 commits) null_blk: format pr_* logs with pr_fmt null_blk: match the type of parameter nr_devices null_blk: do not fail the module load with zero devices block: also check RQF_STATS in blk_mq_need_time_stamp() block: make rq sector size accessible for block stats bfq: Fix bfq linkage error raid5: use bio_end_sector in r5_next_bio raid5: remove STRIPE_OPS_REQ_PENDING md: add feature flag MD_FEATURE_RAID0_LAYOUT md/raid0: avoid RAID0 data corruption due to layout confusion. raid5: don't set STRIPE_HANDLE to stripe which is in batch list raid5: don't increment read_errors on EILSEQ return nvmet: fix a wrong error status returned in error log page nvme: send discovery log page change events to userspace nvme: add uevent variables for controller devices nvme: enable aen regardless of the presence of I/O queues nvme-fabrics: allow discovery subsystems accept a kato nvmet: Use PTR_ERR_OR_ZERO() in nvmet_init_discovery() nvme: Remove redundant assignment of cq vector nvme: Assign subsys instance from first ctrl ...
2019-09-12block: fix race between switching elevator and removing queuesMing Lei1-3/+5
cecf5d87ff20 ("block: split .sysfs_lock into two locks") starts to release & actuire sysfs_lock again during switching elevator. So it isn't enough to prevent switching elevator from happening by simply clearing QUEUE_FLAG_REGISTERED with holding sysfs_lock, because in-progress switch still can move on after re-acquiring the lock, meantime the flag of QUEUE_FLAG_REGISTERED won't get checked. Fixes this issue by checking 'q->elevator' directly & locklessly after q->kobj is removed in blk_unregister_queue(), this way is safe because q->elevator can't be changed at that time. Fixes: cecf5d87ff20 ("block: split .sysfs_lock into two locks") Cc: Christoph Hellwig <hch@infradead.org> Cc: Hannes Reinecke <hare@suse.com> Cc: Greg KH <gregkh@linuxfoundation.org> Cc: Mike Snitzer <snitzer@redhat.com> Cc: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-08-27block: split .sysfs_lock into two locksMing Lei1-18/+28
The kernfs built-in lock of 'kn->count' is held in sysfs .show/.store path. Meantime, inside block's .show/.store callback, q->sysfs_lock is required. However, when mq & iosched kobjects are removed via blk_mq_unregister_dev() & elv_unregister_queue(), q->sysfs_lock is held too. This way causes AB-BA lock because the kernfs built-in lock of 'kn-count' is required inside kobject_del() too, see the lockdep warning[1]. On the other hand, it isn't necessary to acquire q->sysfs_lock for both blk_mq_unregister_dev() & elv_unregister_queue() because clearing REGISTERED flag prevents storing to 'queue/scheduler' from being happened. Also sysfs write(store) is exclusive, so no necessary to hold the lock for elv_unregister_queue() when it is called in switching elevator path. So split .sysfs_lock into two: one is still named as .sysfs_lock for covering sync .store, the other one is named as .sysfs_dir_lock for covering kobjects and related status change. sysfs itself can handle the race between add/remove kobjects and showing/storing attributes under kobjects. For switching scheduler via storing to 'queue/scheduler', we use the queue flag of QUEUE_FLAG_REGISTERED with .sysfs_lock for avoiding the race, then we can avoid to hold .sysfs_lock during removing/adding kobjects. [1] lockdep warning ====================================================== WARNING: possible circular locking dependency detected 5.3.0-rc3-00044-g73277fc75ea0 #1380 Not tainted ------------------------------------------------------ rmmod/777 is trying to acquire lock: 00000000ac50e981 (kn->count#202){++++}, at: kernfs_remove_by_name_ns+0x59/0x72 but task is already holding lock: 00000000fb16ae21 (&q->sysfs_lock){+.+.}, at: blk_unregister_queue+0x78/0x10b which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&q->sysfs_lock){+.+.}: __lock_acquire+0x95f/0xa2f lock_acquire+0x1b4/0x1e8 __mutex_lock+0x14a/0xa9b blk_mq_hw_sysfs_show+0x63/0xb6 sysfs_kf_seq_show+0x11f/0x196 seq_read+0x2cd/0x5f2 vfs_read+0xc7/0x18c ksys_read+0xc4/0x13e do_syscall_64+0xa7/0x295 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #0 (kn->count#202){++++}: check_prev_add+0x5d2/0xc45 validate_chain+0xed3/0xf94 __lock_acquire+0x95f/0xa2f lock_acquire+0x1b4/0x1e8 __kernfs_remove+0x237/0x40b kernfs_remove_by_name_ns+0x59/0x72 remove_files+0x61/0x96 sysfs_remove_group+0x81/0xa4 sysfs_remove_groups+0x3b/0x44 kobject_del+0x44/0x94 blk_mq_unregister_dev+0x83/0xdd blk_unregister_queue+0xa0/0x10b del_gendisk+0x259/0x3fa null_del_dev+0x8b/0x1c3 [null_blk] null_exit+0x5c/0x95 [null_blk] __se_sys_delete_module+0x204/0x337 do_syscall_64+0xa7/0x295 entry_SYSCALL_64_after_hwframe+0x49/0xbe other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&q->sysfs_lock); lock(kn->count#202); lock(&q->sysfs_lock); lock(kn->count#202); *** DEADLOCK *** 2 locks held by rmmod/777: #0: 00000000e69bd9de (&lock){+.+.}, at: null_exit+0x2e/0x95 [null_blk] #1: 00000000fb16ae21 (&q->sysfs_lock){+.+.}, at: blk_unregister_queue+0x78/0x10b stack backtrace: CPU: 0 PID: 777 Comm: rmmod Not tainted 5.3.0-rc3-00044-g73277fc75ea0 #1380 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS ?-20180724_192412-buildhw-07.phx4 Call Trace: dump_stack+0x9a/0xe6 check_noncircular+0x207/0x251 ? print_circular_bug+0x32a/0x32a ? find_usage_backwards+0x84/0xb0 check_prev_add+0x5d2/0xc45 validate_chain+0xed3/0xf94 ? check_prev_add+0xc45/0xc45 ? mark_lock+0x11b/0x804 ? check_usage_forwards+0x1ca/0x1ca __lock_acquire+0x95f/0xa2f lock_acquire+0x1b4/0x1e8 ? kernfs_remove_by_name_ns+0x59/0x72 __kernfs_remove+0x237/0x40b ? kernfs_remove_by_name_ns+0x59/0x72 ? kernfs_next_descendant_post+0x7d/0x7d ? strlen+0x10/0x23 ? strcmp+0x22/0x44 kernfs_remove_by_name_ns+0x59/0x72 remove_files+0x61/0x96 sysfs_remove_group+0x81/0xa4 sysfs_remove_groups+0x3b/0x44 kobject_del+0x44/0x94 blk_mq_unregister_dev+0x83/0xdd blk_unregister_queue+0xa0/0x10b del_gendisk+0x259/0x3fa ? disk_events_poll_msecs_store+0x12b/0x12b ? check_flags+0x1ea/0x204 ? mark_held_locks+0x1f/0x7a null_del_dev+0x8b/0x1c3 [null_blk] null_exit+0x5c/0x95 [null_blk] __se_sys_delete_module+0x204/0x337 ? free_module+0x39f/0x39f ? blkcg_maybe_throttle_current+0x8a/0x718 ? rwlock_bug+0x62/0x62 ? __blkcg_punt_bio_submit+0xd0/0xd0 ? trace_hardirqs_on_thunk+0x1a/0x20 ? mark_held_locks+0x1f/0x7a ? do_syscall_64+0x4c/0x295 do_syscall_64+0xa7/0x295 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x7fb696cdbe6b Code: 73 01 c3 48 8b 0d 1d 20 0c 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 008 RSP: 002b:00007ffec9588788 EFLAGS: 00000206 ORIG_RAX: 00000000000000b0 RAX: ffffffffffffffda RBX: 0000559e589137c0 RCX: 00007fb696cdbe6b RDX: 000000000000000a RSI: 0000000000000800 RDI: 0000559e58913828 RBP: 0000000000000000 R08: 00007ffec9587701 R09: 0000000000000000 R10: 00007fb696d4eae0 R11: 0000000000000206 R12: 00007ffec95889b0 R13: 00007ffec95896b3 R14: 0000559e58913260 R15: 0000559e589137c0 Cc: Christoph Hellwig <hch@infradead.org> Cc: Hannes Reinecke <hare@suse.com> Cc: Greg KH <gregkh@linuxfoundation.org> Cc: Mike Snitzer <snitzer@redhat.com> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-08-27block: add helper for checking if queue is registeredMing Lei1-2/+2
There are 4 users which check if queue is registered, so add one helper to check it. Cc: Christoph Hellwig <hch@infradead.org> Cc: Hannes Reinecke <hare@suse.com> Cc: Greg KH <gregkh@linuxfoundation.org> Cc: Mike Snitzer <snitzer@redhat.com> Cc: Bart Van Assche <bvanassche@acm.org> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.