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2020-01-07dm snapshot: use true/false for bool variablezhengbin1-3/+3
Fixes coccicheck warning: drivers/md/dm-snap.c:1064:3-18: WARNING: Assignment of 0/1 to bool variable drivers/md/dm-snap.c:1152:1-16: WARNING: Assignment of 0/1 to bool variable drivers/md/dm-snap.c:1317:1-16: WARNING: Assignment of 0/1 to bool variable Reported-by: Hulk Robot <hulkci@huawei.com> Signed-off-by: zhengbin <zhengbin13@huawei.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2019-10-10dm snapshot: rework COW throttling to fix deadlockMikulas Patocka1-14/+64
Commit 721b1d98fb517a ("dm snapshot: Fix excessive memory usage and workqueue stalls") introduced a semaphore to limit the maximum number of in-flight kcopyd (COW) jobs. The implementation of this throttling mechanism is prone to a deadlock: 1. One or more threads write to the origin device causing COW, which is performed by kcopyd. 2. At some point some of these threads might reach the s->cow_count semaphore limit and block in down(&s->cow_count), holding a read lock on _origins_lock. 3. Someone tries to acquire a write lock on _origins_lock, e.g., snapshot_ctr(), which blocks because the threads at step (2) already hold a read lock on it. 4. A COW operation completes and kcopyd runs dm-snapshot's completion callback, which ends up calling pending_complete(). pending_complete() tries to resubmit any deferred origin bios. This requires acquiring a read lock on _origins_lock, which blocks. This happens because the read-write semaphore implementation gives priority to writers, meaning that as soon as a writer tries to enter the critical section, no readers will be allowed in, until all writers have completed their work. So, pending_complete() waits for the writer at step (3) to acquire and release the lock. This writer waits for the readers at step (2) to release the read lock and those readers wait for pending_complete() (the kcopyd thread) to signal the s->cow_count semaphore: DEADLOCK. The above was thoroughly analyzed and documented by Nikos Tsironis as part of his initial proposal for fixing this deadlock, see: https://www.redhat.com/archives/dm-devel/2019-October/msg00001.html Fix this deadlock by reworking COW throttling so that it waits without holding any locks. Add a variable 'in_progress' that counts how many kcopyd jobs are running. A function wait_for_in_progress() will sleep if 'in_progress' is over the limit. It drops _origins_lock in order to avoid the deadlock. Reported-by: Guruswamy Basavaiah <guru2018@gmail.com> Reported-by: Nikos Tsironis <ntsironis@arrikto.com> Reviewed-by: Nikos Tsironis <ntsironis@arrikto.com> Tested-by: Nikos Tsironis <ntsironis@arrikto.com> Fixes: 721b1d98fb51 ("dm snapshot: Fix excessive memory usage and workqueue stalls") Cc: stable@vger.kernel.org # v5.0+ Depends-on: 4a3f111a73a8c ("dm snapshot: introduce account_start_copy() and account_end_copy()") Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2019-10-10dm snapshot: introduce account_start_copy() and account_end_copy()Mikulas Patocka1-5/+15
This simple refactoring moves code for modifying the semaphore cow_count into separate functions to prepare for changes that will extend these methods to provide for a more sophisticated mechanism for COW throttling. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Reviewed-by: Nikos Tsironis <ntsironis@arrikto.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2019-07-17dm snapshot: fix oversights in optional discard supportMike Snitzer1-0/+10
__find_snapshots_sharing_cow() should always be used with _origins_lock held so fix snapshot_io_hints() accordingly. Also, once a snapshot is being merged discards must not be allowed -- otherwise incorrect or duplicate work will be performed. Fixes: 2e6023850e177d ("dm snapshot: add optional discard support features") Reported-by: Nikos Tsironis <ntsironis@arrikto.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2019-07-12dm snapshot: add optional discard support featuresMike Snitzer1-21/+165
discard_zeroes_cow - a discard issued to the snapshot device that maps to entire chunks to will zero the corresponding exception(s) in the snapshot's exception store. discard_passdown_origin - a discard to the snapshot device is passed down to the snapshot-origin's underlying device. This doesn't cause copy-out to the snapshot exception store because the snapshot-origin target is bypassed. The discard_passdown_origin feature depends on the discard_zeroes_cow feature being enabled. When these 2 features are enabled they allow a temporarily read-only device that has completely exhausted its free space to recover space. To do so dm-snapshot provides temporary buffer to accommodate writes that the temporarily read-only device cannot handle yet. Once the upper layer frees space (e.g. fstrim to XFS) the discards issued to the dm-snapshot target will be issued to underlying read-only device whose free space was exhausted. In addition those discards will also cause zeroes to be written to the snapshot exception store if corresponding exceptions exist. If the underlying origin device provides deduplication for zero blocks then if/when the snapshot is merged backed to the origin those blocks will become unused. Once the origin has gained adequate space, merging the snapshot back to the thinly provisioned device will permit continued use of that device without the temporary space provided by the snapshot. Requested-by: John Dorminy <jdorminy@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2019-04-18dm snapshot: Use fine-grained locking schemeNikos Tsironis1-40/+44
Substitute the global locking scheme with a fine grained one, employing the read-write semaphore and the scalable exception tables with per-bucket locks introduced by the previous two commits. Summarizing, we now use a read-write semaphore to protect the mostly read fields of the snapshot structure, e.g., valid, active, etc., and per-bucket bit spinlocks to protect accesses to the complete and pending exception tables. Finally, we use an extra spinlock (pe_allocation_lock) to serialize the allocation of new exceptions by the exception store. This allocation is really fast, so the extra spinlock doesn't hurt the performance. This scheme allows dm-snapshot to scale better, resulting in increased IOPS and reduced latency. Following are some benchmark results using the null_blk device: modprobe null_blk gb=1024 bs=512 submit_queues=8 hw_queue_depth=4096 \ queue_mode=2 irqmode=1 completion_nsec=1 nr_devices=1 * Benchmark fio_origin_randwrite_throughput_N, from the device mapper test suite [1] (direct IO, random 4K writes to origin device, IO engine libaio): +--------------+-------------+------------+ | # of workers | IOPS Before | IOPS After | +--------------+-------------+------------+ | 1 | 57708 | 66421 | | 2 | 63415 | 77589 | | 4 | 67276 | 98839 | | 8 | 60564 | 109258 | +--------------+-------------+------------+ * Benchmark fio_origin_randwrite_latency_N, from the device mapper test suite [1] (direct IO, random 4K writes to origin device, IO engine psync): +--------------+-----------------------+----------------------+ | # of workers | Latency (usec) Before | Latency (usec) After | +--------------+-----------------------+----------------------+ | 1 | 16.25 | 13.27 | | 2 | 31.65 | 25.08 | | 4 | 55.28 | 41.08 | | 8 | 121.47 | 74.44 | +--------------+-----------------------+----------------------+ * Benchmark fio_snapshot_randwrite_throughput_N, from the device mapper test suite [1] (direct IO, random 4K writes to snapshot device, IO engine libaio): +--------------+-------------+------------+ | # of workers | IOPS Before | IOPS After | +--------------+-------------+------------+ | 1 | 72593 | 84938 | | 2 | 97379 | 134973 | | 4 | 90610 | 143077 | | 8 | 90537 | 180085 | +--------------+-------------+------------+ * Benchmark fio_snapshot_randwrite_latency_N, from the device mapper test suite [1] (direct IO, random 4K writes to snapshot device, IO engine psync): +--------------+-----------------------+----------------------+ | # of workers | Latency (usec) Before | Latency (usec) After | +--------------+-----------------------+----------------------+ | 1 | 12.53 | 10.6 | | 2 | 19.78 | 14.89 | | 4 | 40.37 | 23.47 | | 8 | 89.32 | 48.48 | +--------------+-----------------------+----------------------+ [1] https://github.com/jthornber/device-mapper-test-suite Co-developed-by: Ilias Tsitsimpis <iliastsi@arrikto.com> Signed-off-by: Nikos Tsironis <ntsironis@arrikto.com> Acked-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2019-04-18dm snapshot: Make exception tables scalableNikos Tsironis1-23/+114
Use list_bl to implement the exception hash tables' buckets. This change permits concurrent access, to distinct buckets, by multiple threads. Also, implement helper functions to lock and unlock the exception tables based on the chunk number of the exception at hand. We retain the global locking, by means of down_write(), which is replaced by the next commit. Still, we must acquire the per-bucket spinlocks when accessing the hash tables, since list_bl does not allow modification on unlocked lists. Co-developed-by: Ilias Tsitsimpis <iliastsi@arrikto.com> Signed-off-by: Nikos Tsironis <ntsironis@arrikto.com> Acked-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2019-04-18dm snapshot: Replace mutex with rw semaphoreNikos Tsironis1-45/+43
dm-snapshot uses a single mutex to serialize every access to the snapshot state. This includes all accesses to the complete and pending exception tables, which occur at every origin write, every snapshot read/write and every exception completion. The lock statistics indicate that this mutex is a bottleneck (average wait time ~480 usecs for 8 processes doing random 4K writes to the origin device) preventing dm-snapshot to scale as the number of threads doing IO increases. The major contention points are __origin_write()/snapshot_map() and pending_complete(), i.e., the submission and completion of pending exceptions. Replace this mutex with a rw semaphore. We essentially revert commit ae1093be5a0ef9 ("dm snapshot: use mutex instead of rw_semaphore") and together with the next two patches we substitute the single mutex with a fine-grained locking scheme, where we use a read-write semaphore to protect the mostly read fields of the snapshot structure, e.g., valid, active, etc., and per-bucket bit spinlocks to protect accesses to the complete and pending exception tables. Co-developed-by: Ilias Tsitsimpis <iliastsi@arrikto.com> Signed-off-by: Nikos Tsironis <ntsironis@arrikto.com> Acked-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2019-04-18dm snapshot: Don't sleep holding the snapshot lockNikos Tsironis1-37/+65
When completing a pending exception, pending_complete() waits for all conflicting reads to drain, before inserting the final, completed exception. Conflicting reads are snapshot reads redirected to the origin, because the relevant chunk is not remapped to the COW device the moment we receive the read. The completed exception must be inserted into the exception table after all conflicting reads drain to ensure snapshot reads don't return corrupted data. This is required because inserting the completed exception into the exception table signals that the relevant chunk is remapped and both origin writes and snapshot merging will now overwrite the chunk in origin. This wait is done holding the snapshot lock to ensure that pending_complete() doesn't starve if new snapshot reads keep coming for this chunk. In preparation for the next commit, where we use a spinlock instead of a mutex to protect the exception tables, we remove the need for holding the lock while waiting for conflicting reads to drain. We achieve this in two steps: 1. pending_complete() inserts the completed exception before waiting for conflicting reads to drain and removes the pending exception after all conflicting reads drain. This ensures that new snapshot reads will be redirected to the COW device, instead of the origin, and thus pending_complete() will not starve. Moreover, we use the existence of both a completed and a pending exception to signify that the COW is done but there are conflicting reads in flight. 2. In __origin_write() we check first if there is a pending exception and then if there is a completed exception. If there is a pending exception any submitted BIO is delayed on the pe->origin_bios list and DM_MAPIO_SUBMITTED is returned. This ensures that neither writes to the origin nor snapshot merging can overwrite the origin chunk, until all conflicting reads drain, and thus snapshot reads will not return corrupted data. Summarizing, we now have the following possible combinations of pending and completed exceptions for a chunk, along with their meaning: A. No exceptions exist: The chunk has not been remapped yet. B. Only a pending exception exists: The chunk is currently being copied to the COW device. C. Both a pending and a completed exception exist: COW for this chunk has completed but there are snapshot reads in flight which had been redirected to the origin before the chunk was remapped. D. Only the completed exception exists: COW has been completed and there are no conflicting reads in flight. Co-developed-by: Ilias Tsitsimpis <iliastsi@arrikto.com> Signed-off-by: Nikos Tsironis <ntsironis@arrikto.com> Acked-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2019-03-05dm snapshot: don't define direct_access if we don't support itMikulas Patocka1-8/+0
Don't define a direct_access function that fails, dm_dax_direct_access already fails with -EIO if the pointer is zero; Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2018-12-18dm snapshot: Fix excessive memory usage and workqueue stallsNikos Tsironis1-0/+22
kcopyd has no upper limit to the number of jobs one can allocate and issue. Under certain workloads this can lead to excessive memory usage and workqueue stalls. For example, when creating multiple dm-snapshot targets with a 4K chunk size and then writing to the origin through the page cache. Syncing the page cache causes a large number of BIOs to be issued to the dm-snapshot origin target, which itself issues an even larger (because of the BIO splitting taking place) number of kcopyd jobs. Running the following test, from the device mapper test suite [1], dmtest run --suite snapshot -n many_snapshots_of_same_volume_N , with 8 active snapshots, results in the kcopyd job slab cache growing to 10G. Depending on the available system RAM this can lead to the OOM killer killing user processes: [463.492878] kthreadd invoked oom-killer: gfp_mask=0x6040c0(GFP_KERNEL|__GFP_COMP), nodemask=(null), order=1, oom_score_adj=0 [463.492894] kthreadd cpuset=/ mems_allowed=0 [463.492948] CPU: 7 PID: 2 Comm: kthreadd Not tainted 4.19.0-rc7 #3 [463.492950] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014 [463.492952] Call Trace: [463.492964] dump_stack+0x7d/0xbb [463.492973] dump_header+0x6b/0x2fc [463.492987] ? lockdep_hardirqs_on+0xee/0x190 [463.493012] oom_kill_process+0x302/0x370 [463.493021] out_of_memory+0x113/0x560 [463.493030] __alloc_pages_slowpath+0xf40/0x1020 [463.493055] __alloc_pages_nodemask+0x348/0x3c0 [463.493067] cache_grow_begin+0x81/0x8b0 [463.493072] ? cache_grow_begin+0x874/0x8b0 [463.493078] fallback_alloc+0x1e4/0x280 [463.493092] kmem_cache_alloc_node+0xd6/0x370 [463.493098] ? copy_process.part.31+0x1c5/0x20d0 [463.493105] copy_process.part.31+0x1c5/0x20d0 [463.493115] ? __lock_acquire+0x3cc/0x1550 [463.493121] ? __switch_to_asm+0x34/0x70 [463.493129] ? kthread_create_worker_on_cpu+0x70/0x70 [463.493135] ? finish_task_switch+0x90/0x280 [463.493165] _do_fork+0xe0/0x6d0 [463.493191] ? kthreadd+0x19f/0x220 [463.493233] kernel_thread+0x25/0x30 [463.493235] kthreadd+0x1bf/0x220 [463.493242] ? kthread_create_on_cpu+0x90/0x90 [463.493248] ret_from_fork+0x3a/0x50 [463.493279] Mem-Info: [463.493285] active_anon:20631 inactive_anon:4831 isolated_anon:0 [463.493285] active_file:80216 inactive_file:80107 isolated_file:435 [463.493285] unevictable:0 dirty:51266 writeback:109372 unstable:0 [463.493285] slab_reclaimable:31191 slab_unreclaimable:3483521 [463.493285] mapped:526 shmem:4903 pagetables:1759 bounce:0 [463.493285] free:33623 free_pcp:2392 free_cma:0 ... [463.493489] Unreclaimable slab info: [463.493513] Name Used Total [463.493522] bio-6 1028KB 1028KB [463.493525] bio-5 1028KB 1028KB [463.493528] dm_snap_pending_exception 236783KB 243789KB [463.493531] dm_exception 41KB 42KB [463.493534] bio-4 1216KB 1216KB [463.493537] bio-3 439396KB 439396KB [463.493539] kcopyd_job 6973427KB 6973427KB ... [463.494340] Out of memory: Kill process 1298 (ruby2.3) score 1 or sacrifice child [463.494673] Killed process 1298 (ruby2.3) total-vm:435740kB, anon-rss:20180kB, file-rss:4kB, shmem-rss:0kB [463.506437] oom_reaper: reaped process 1298 (ruby2.3), now anon-rss:0kB, file-rss:0kB, shmem-rss:0kB Moreover, issuing a large number of kcopyd jobs results in kcopyd hogging the CPU, while processing them. As a result, processing of work items, queued for execution on the same CPU as the currently running kcopyd thread, is stalled for long periods of time, hurting performance. Running the aforementioned test we get, in dmesg, messages like the following: [67501.194592] BUG: workqueue lockup - pool cpus=4 node=0 flags=0x0 nice=0 stuck for 27s! [67501.195586] Showing busy workqueues and worker pools: [67501.195591] workqueue events: flags=0x0 [67501.195597] pwq 8: cpus=4 node=0 flags=0x0 nice=0 active=1/256 [67501.195611] pending: cache_reap [67501.195641] workqueue mm_percpu_wq: flags=0x8 [67501.195645] pwq 8: cpus=4 node=0 flags=0x0 nice=0 active=1/256 [67501.195656] pending: vmstat_update [67501.195682] workqueue kblockd: flags=0x18 [67501.195687] pwq 5: cpus=2 node=0 flags=0x0 nice=-20 active=1/256 [67501.195698] pending: blk_timeout_work [67501.195753] workqueue kcopyd: flags=0x8 [67501.195757] pwq 8: cpus=4 node=0 flags=0x0 nice=0 active=1/256 [67501.195768] pending: do_work [dm_mod] [67501.195802] workqueue kcopyd: flags=0x8 [67501.195806] pwq 8: cpus=4 node=0 flags=0x0 nice=0 active=1/256 [67501.195817] pending: do_work [dm_mod] [67501.195834] workqueue kcopyd: flags=0x8 [67501.195838] pwq 8: cpus=4 node=0 flags=0x0 nice=0 active=1/256 [67501.195848] pending: do_work [dm_mod] [67501.195881] workqueue kcopyd: flags=0x8 [67501.195885] pwq 8: cpus=4 node=0 flags=0x0 nice=0 active=1/256 [67501.195896] pending: do_work [dm_mod] [67501.195920] workqueue kcopyd: flags=0x8 [67501.195924] pwq 8: cpus=4 node=0 flags=0x0 nice=0 active=2/256 [67501.195935] in-flight: 67:do_work [dm_mod] [67501.195945] pending: do_work [dm_mod] [67501.195961] pool 8: cpus=4 node=0 flags=0x0 nice=0 hung=27s workers=3 idle: 129 23765 The root cause for these issues is the way dm-snapshot uses kcopyd. In particular, the lack of an explicit or implicit limit to the maximum number of in-flight COW jobs. The merging path is not affected because it implicitly limits the in-flight kcopyd jobs to one. Fix these issues by using a semaphore to limit the maximum number of in-flight kcopyd jobs. We grab the semaphore before allocating a new kcopyd job in start_copy() and start_full_bio() and release it after the job finishes in copy_callback(). The initial semaphore value is configurable through a module parameter, to allow fine tuning the maximum number of in-flight COW jobs. Setting this parameter to zero initializes the semaphore to INT_MAX. A default value of 2048 maximum in-flight kcopyd jobs was chosen. This value was decided experimentally as a trade-off between memory consumption, stalling the kernel's workqueues and maintaining a high enough throughput. Re-running the aforementioned test: * Workqueue stalls are eliminated * kcopyd's job slab cache uses a maximum of 130MB * The time taken by the test to write to the snapshot-origin target is reduced from 05m20.48s to 03m26.38s [1] https://github.com/jthornber/device-mapper-test-suite Signed-off-by: Nikos Tsironis <ntsironis@arrikto.com> Signed-off-by: Ilias Tsitsimpis <iliastsi@arrikto.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2018-08-09dm snapshot: remove stale FIXME in snapshot_map()Mike Snitzer1-2/+0
Commit ae1093be ("dm snapshot: use mutex instead of rw_semaphore") eliminated the need to worry about read vs write locking. So remove a FIXME in snapshot_map() that is concerned about selectively taking a write lock. Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2018-08-08dm snapshot: improve performance by switching out_of_order_list to rbtreeDavid Jeffery1-13/+26
copy_complete()'s processing of out_of_order_list can result in quadratic complexity in the worst case. As such it was the source of consuming too much cpu and the source of significant loss in performance. Fix this by converting out_of_order_list to an rbtree. This improved a dm-snapshot test copy workload from 32 seconds to 4 seconds. Signed-off-by: David Jeffery <djeffery@redhat.com> Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Tested-by: Brett Hull <bhull@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2018-06-13treewide: kmalloc() -> kmalloc_array()Kees Cook1-4/+5
The kmalloc() function has a 2-factor argument form, kmalloc_array(). This patch replaces cases of: kmalloc(a * b, gfp) with: kmalloc_array(a * b, gfp) as well as handling cases of: kmalloc(a * b * c, gfp) with: kmalloc(array3_size(a, b, c), gfp) as it's slightly less ugly than: kmalloc_array(array_size(a, b), c, gfp) This does, however, attempt to ignore constant size factors like: kmalloc(4 * 1024, gfp) though any constants defined via macros get caught up in the conversion. Any factors with a sizeof() of "unsigned char", "char", and "u8" were dropped, since they're redundant. The tools/ directory was manually excluded, since it has its own implementation of kmalloc(). The Coccinelle script used for this was: // Fix redundant parens around sizeof(). @@ type TYPE; expression THING, E; @@ ( kmalloc( - (sizeof(TYPE)) * E + sizeof(TYPE) * E , ...) | kmalloc( - (sizeof(THING)) * E + sizeof(THING) * E , ...) ) // Drop single-byte sizes and redundant parens. @@ expression COUNT; typedef u8; typedef __u8; @@ ( kmalloc( - sizeof(u8) * (COUNT) + COUNT , ...) | kmalloc( - sizeof(__u8) * (COUNT) + COUNT , ...) | kmalloc( - sizeof(char) * (COUNT) + COUNT , ...) | kmalloc( - sizeof(unsigned char) * (COUNT) + COUNT , ...) | kmalloc( - sizeof(u8) * COUNT + COUNT , ...) | kmalloc( - sizeof(__u8) * COUNT + COUNT , ...) | kmalloc( - sizeof(char) * COUNT + COUNT , ...) | kmalloc( - sizeof(unsigned char) * COUNT + COUNT , ...) ) // 2-factor product with sizeof(type/expression) and identifier or constant. @@ type TYPE; expression THING; identifier COUNT_ID; constant COUNT_CONST; @@ ( - kmalloc + kmalloc_array ( - sizeof(TYPE) * (COUNT_ID) + COUNT_ID, sizeof(TYPE) , ...) | - kmalloc + kmalloc_array ( - sizeof(TYPE) * COUNT_ID + COUNT_ID, sizeof(TYPE) , ...) | - kmalloc + kmalloc_array ( - sizeof(TYPE) * (COUNT_CONST) + COUNT_CONST, sizeof(TYPE) , ...) | - kmalloc + kmalloc_array ( - sizeof(TYPE) * COUNT_CONST + COUNT_CONST, sizeof(TYPE) , ...) | - kmalloc + kmalloc_array ( - sizeof(THING) * (COUNT_ID) + COUNT_ID, sizeof(THING) , ...) | - kmalloc + kmalloc_array ( - sizeof(THING) * COUNT_ID + COUNT_ID, sizeof(THING) , ...) | - kmalloc + kmalloc_array ( - sizeof(THING) * (COUNT_CONST) + COUNT_CONST, sizeof(THING) , ...) | - kmalloc + kmalloc_array ( - sizeof(THING) * COUNT_CONST + COUNT_CONST, sizeof(THING) , ...) ) // 2-factor product, only identifiers. @@ identifier SIZE, COUNT; @@ - kmalloc + kmalloc_array ( - SIZE * COUNT + COUNT, SIZE , ...) // 3-factor product with 1 sizeof(type) or sizeof(expression), with // redundant parens removed. @@ expression THING; identifier STRIDE, COUNT; type TYPE; @@ ( kmalloc( - sizeof(TYPE) * (COUNT) * (STRIDE) + array3_size(COUNT, STRIDE, sizeof(TYPE)) , ...) | kmalloc( - sizeof(TYPE) * (COUNT) * STRIDE + array3_size(COUNT, STRIDE, sizeof(TYPE)) , ...) | kmalloc( - sizeof(TYPE) * COUNT * (STRIDE) + array3_size(COUNT, STRIDE, sizeof(TYPE)) , ...) | kmalloc( - sizeof(TYPE) * COUNT * STRIDE + array3_size(COUNT, STRIDE, sizeof(TYPE)) , ...) | kmalloc( - sizeof(THING) * (COUNT) * (STRIDE) + array3_size(COUNT, STRIDE, sizeof(THING)) , ...) | kmalloc( - sizeof(THING) * (COUNT) * STRIDE + array3_size(COUNT, STRIDE, sizeof(THING)) , ...) | kmalloc( - sizeof(THING) * COUNT * (STRIDE) + array3_size(COUNT, STRIDE, sizeof(THING)) , ...) | kmalloc( - sizeof(THING) * COUNT * STRIDE + array3_size(COUNT, STRIDE, sizeof(THING)) , ...) ) // 3-factor product with 2 sizeof(variable), with redundant parens removed. @@ expression THING1, THING2; identifier COUNT; type TYPE1, TYPE2; @@ ( kmalloc( - sizeof(TYPE1) * sizeof(TYPE2) * COUNT + array3_size(COUNT, sizeof(TYPE1), sizeof(TYPE2)) , ...) | kmalloc( - sizeof(TYPE1) * sizeof(THING2) * (COUNT) + array3_size(COUNT, sizeof(TYPE1), sizeof(TYPE2)) , ...) | kmalloc( - sizeof(THING1) * sizeof(THING2) * COUNT + array3_size(COUNT, sizeof(THING1), sizeof(THING2)) , ...) | kmalloc( - sizeof(THING1) * sizeof(THING2) * (COUNT) + array3_size(COUNT, sizeof(THING1), sizeof(THING2)) , ...) | kmalloc( - sizeof(TYPE1) * sizeof(THING2) * COUNT + array3_size(COUNT, sizeof(TYPE1), sizeof(THING2)) , ...) | kmalloc( - sizeof(TYPE1) * sizeof(THING2) * (COUNT) + array3_size(COUNT, sizeof(TYPE1), sizeof(THING2)) , ...) ) // 3-factor product, only identifiers, with redundant parens removed. @@ identifier STRIDE, SIZE, COUNT; @@ ( kmalloc( - (COUNT) * STRIDE * SIZE + array3_size(COUNT, STRIDE, SIZE) , ...) | kmalloc( - COUNT * (STRIDE) * SIZE + array3_size(COUNT, STRIDE, SIZE) , ...) | kmalloc( - COUNT * STRIDE * (SIZE) + array3_size(COUNT, STRIDE, SIZE) , ...) | kmalloc( - (COUNT) * (STRIDE) * SIZE + array3_size(COUNT, STRIDE, SIZE) , ...) | kmalloc( - COUNT * (STRIDE) * (SIZE) + array3_size(COUNT, STRIDE, SIZE) , ...) | kmalloc( - (COUNT) * STRIDE * (SIZE) + array3_size(COUNT, STRIDE, SIZE) , ...) | kmalloc( - (COUNT) * (STRIDE) * (SIZE) + array3_size(COUNT, STRIDE, SIZE) , ...) | kmalloc( - COUNT * STRIDE * SIZE + array3_size(COUNT, STRIDE, SIZE) , ...) ) // Any remaining multi-factor products, first at least 3-factor products, // when they're not all constants... @@ expression E1, E2, E3; constant C1, C2, C3; @@ ( kmalloc(C1 * C2 * C3, ...) | kmalloc( - (E1) * E2 * E3 + array3_size(E1, E2, E3) , ...) | kmalloc( - (E1) * (E2) * E3 + array3_size(E1, E2, E3) , ...) | kmalloc( - (E1) * (E2) * (E3) + array3_size(E1, E2, E3) , ...) | kmalloc( - E1 * E2 * E3 + array3_size(E1, E2, E3) , ...) ) // And then all remaining 2 factors products when they're not all constants, // keeping sizeof() as the second factor argument. @@ expression THING, E1, E2; type TYPE; constant C1, C2, C3; @@ ( kmalloc(sizeof(THING) * C2, ...) | kmalloc(sizeof(TYPE) * C2, ...) | kmalloc(C1 * C2 * C3, ...) | kmalloc(C1 * C2, ...) | - kmalloc + kmalloc_array ( - sizeof(TYPE) * (E2) + E2, sizeof(TYPE) , ...) | - kmalloc + kmalloc_array ( - sizeof(TYPE) * E2 + E2, sizeof(TYPE) , ...) | - kmalloc + kmalloc_array ( - sizeof(THING) * (E2) + E2, sizeof(THING) , ...) | - kmalloc + kmalloc_array ( - sizeof(THING) * E2 + E2, sizeof(THING) , ...) | - kmalloc + kmalloc_array ( - (E1) * E2 + E1, E2 , ...) | - kmalloc + kmalloc_array ( - (E1) * (E2) + E1, E2 , ...) | - kmalloc + kmalloc_array ( - E1 * E2 + E1, E2 , ...) ) Signed-off-by: Kees Cook <keescook@chromium.org>
2018-06-05dm: Use kzalloc for all structs with embedded biosets/mempoolsKent Overstreet1-1/+1
mempool_init()/bioset_init() require that the mempools/biosets be zeroed first; they probably should not _require_ this, but not allocating those structs with kzalloc is a fairly nonsensical thing to do (calling mempool_exit()/bioset_exit() on an uninitialized mempool/bioset is legal and safe, but only works if said memory was zeroed.) Acked-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-05-31dm: convert to bioset_init()/mempool_init()Kent Overstreet1-9/+8
Convert dm to embedded bio sets. Acked-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-17dm snapshot: use mutex instead of rw_semaphoreMikulas Patocka1-41/+43
The rw_semaphore is acquired for read only in two places, neither is performance-critical. So replace it with a mutex -- which is more efficient. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2017-12-04dm: fix various targets to dm_register_target after module __init resources ↵monty_pavel@sina.com1-24/+24
created A NULL pointer is seen if two concurrent "vgchange -ay -K <vg name>" processes race to load the dm-thin-pool module: PID: 25992 TASK: ffff883cd7d23500 CPU: 4 COMMAND: "vgchange" #0 [ffff883cd743d600] machine_kexec at ffffffff81038fa9 0000001 [ffff883cd743d660] crash_kexec at ffffffff810c5992 0000002 [ffff883cd743d730] oops_end at ffffffff81515c90 0000003 [ffff883cd743d760] no_context at ffffffff81049f1b 0000004 [ffff883cd743d7b0] __bad_area_nosemaphore at ffffffff8104a1a5 0000005 [ffff883cd743d800] bad_area at ffffffff8104a2ce 0000006 [ffff883cd743d830] __do_page_fault at ffffffff8104aa6f 0000007 [ffff883cd743d950] do_page_fault at ffffffff81517bae 0000008 [ffff883cd743d980] page_fault at ffffffff81514f95 [exception RIP: kmem_cache_alloc+108] RIP: ffffffff8116ef3c RSP: ffff883cd743da38 RFLAGS: 00010046 RAX: 0000000000000004 RBX: ffffffff81121b90 RCX: ffff881bf1e78cc0 RDX: 0000000000000000 RSI: 00000000000000d0 RDI: 0000000000000000 RBP: ffff883cd743da68 R8: ffff881bf1a4eb00 R9: 0000000080042000 R10: 0000000000002000 R11: 0000000000000000 R12: 00000000000000d0 R13: 0000000000000000 R14: 00000000000000d0 R15: 0000000000000246 ORIG_RAX: ffffffffffffffff CS: 0010 SS: 0018 0000009 [ffff883cd743da70] mempool_alloc_slab at ffffffff81121ba5 0000010 [ffff883cd743da80] mempool_create_node at ffffffff81122083 0000011 [ffff883cd743dad0] mempool_create at ffffffff811220f4 0000012 [ffff883cd743dae0] pool_ctr at ffffffffa08de049 [dm_thin_pool] 0000013 [ffff883cd743dbd0] dm_table_add_target at ffffffffa0005f2f [dm_mod] 0000014 [ffff883cd743dc30] table_load at ffffffffa0008ba9 [dm_mod] 0000015 [ffff883cd743dc90] ctl_ioctl at ffffffffa0009dc4 [dm_mod] The race results in a NULL pointer because: Process A (vgchange -ay -K): a. send DM_LIST_VERSIONS_CMD ioctl; b. pool_target not registered; c. modprobe dm_thin_pool and wait until end. Process B (vgchange -ay -K): a. send DM_LIST_VERSIONS_CMD ioctl; b. pool_target registered; c. table_load->dm_table_add_target->pool_ctr; d. _new_mapping_cache is NULL and panic. Note: 1. process A and process B are two concurrent processes. 2. pool_target can be detected by process B but _new_mapping_cache initialization has not ended. To fix dm-thin-pool, and other targets (cache, multipath, and snapshot) with the same problem, simply dm_register_target() after all resources created during module init (as labelled with __init) are finished. Cc: stable@vger.kernel.org Signed-off-by: monty <monty_pavel@sina.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2017-08-23block: replace bi_bdev with a gendisk pointer and partitions indexChristoph Hellwig1-8/+8
This way we don't need a block_device structure to submit I/O. The block_device has different life time rules from the gendisk and request_queue and is usually only available when the block device node is open. Other callers need to explicitly create one (e.g. the lightnvm passthrough code, or the new nvme multipathing code). For the actual I/O path all that we need is the gendisk, which exists once per block device. But given that the block layer also does partition remapping we additionally need a partition index, which is used for said remapping in generic_make_request. Note that all the block drivers generally want request_queue or sometimes the gendisk, so this removes a layer of indirection all over the stack. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-06-09block: switch bios to blk_status_tChristoph Hellwig1-2/+3
Replace bi_error with a new bi_status to allow for a clear conversion. Note that device mapper overloaded bi_error with a private value, which we'll have to keep arround at least for now and thus propagate to a proper blk_status_t value. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
2017-06-09dm: change ->end_io calling conventionChristoph Hellwig1-2/+2
Turn the error paramter into a pointer so that target drivers can change the value, and make sure only DM_ENDIO_* values are returned from the methods. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2017-06-09dm: don't return errnos from ->mapChristoph Hellwig1-4/+4
Instead use the special DM_MAPIO_KILL return value to return -EIO just like we do for the request based path. Note that dm-log-writes returned -ENOMEM in a few places, which now becomes -EIO instead. No consumer treats -ENOMEM special so this shouldn't be an issue (and it should use a mempool to start with to make guaranteed progress). Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2017-04-25dm: teach dm-targets to use a dax_device + dax_operationsDan Williams1-3/+3
Arrange for dm to lookup the dax services available from member devices. Update the dax-capable targets, linear and stripe, to route dax operations to the underlying device. Changes the target-internal ->direct_access() method to more closely align with the dax_operations ->direct_access() calling convention. Cc: Toshi Kani <toshi.kani@hpe.com> Reviewed-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2016-08-07block: rename bio bi_rw to bi_opfJens Axboe1-3/+3
Since commit 63a4cc24867d, bio->bi_rw contains flags in the lower portion and the op code in the higher portions. This means that old code that relies on manually setting bi_rw is most likely going to be broken. Instead of letting that brokeness linger, rename the member, to force old and out-of-tree code to break at compile time instead of at runtime. No intended functional changes in this commit. Signed-off-by: Jens Axboe <axboe@fb.com>
2016-07-29Merge tag 'libnvdimm-for-4.8' of ↵Linus Torvalds1-1/+1
git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm Pull libnvdimm updates from Dan Williams: - Replace pcommit with ADR / directed-flushing. The pcommit instruction, which has not shipped on any product, is deprecated. Instead, the requirement is that platforms implement either ADR, or provide one or more flush addresses per nvdimm. ADR (Asynchronous DRAM Refresh) flushes data in posted write buffers to the memory controller on a power-fail event. Flush addresses are defined in ACPI 6.x as an NVDIMM Firmware Interface Table (NFIT) sub-structure: "Flush Hint Address Structure". A flush hint is an mmio address that when written and fenced assures that all previous posted writes targeting a given dimm have been flushed to media. - On-demand ARS (address range scrub). Linux uses the results of the ACPI ARS commands to track bad blocks in pmem devices. When latent errors are detected we re-scrub the media to refresh the bad block list, userspace can also request a re-scrub at any time. - Support for the Microsoft DSM (device specific method) command format. - Support for EDK2/OVMF virtual disk device memory ranges. - Various fixes and cleanups across the subsystem. * tag 'libnvdimm-for-4.8' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm: (41 commits) libnvdimm-btt: Delete an unnecessary check before the function call "__nd_device_register" nfit: do an ARS scrub on hitting a latent media error nfit: move to nfit/ sub-directory nfit, libnvdimm: allow an ARS scrub to be triggered on demand libnvdimm: register nvdimm_bus devices with an nd_bus driver pmem: clarify a debug print in pmem_clear_poison x86/insn: remove pcommit Revert "KVM: x86: add pcommit support" nfit, tools/testing/nvdimm/: unify shutdown paths libnvdimm: move ->module to struct nvdimm_bus_descriptor nfit: cleanup acpi_nfit_init calling convention nfit: fix _FIT evaluation memory leak + use after free tools/testing/nvdimm: add manufacturing_{date|location} dimm properties tools/testing/nvdimm: add virtual ramdisk range acpi, nfit: treat virtual ramdisk SPA as pmem region pmem: kill __pmem address space pmem: kill wmb_pmem() libnvdimm, pmem: use nvdimm_flush() for namespace I/O writes fs/dax: remove wmb_pmem() libnvdimm, pmem: flush posted-write queues on shutdown ...
2016-07-27Merge tag 'dm-4.8-changes' of ↵Linus Torvalds1-0/+8
git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm Pull device mapper updates from Mike Snitzer: - initially based on Jens' 'for-4.8/core' (given all the flag churn) and later merged with 'for-4.8/core' to pickup the QUEUE_FLAG_DAX commits that DM depends on to provide its DAX support - clean up the bio-based vs request-based DM core code by moving the request-based DM core code out to dm-rq.[hc] - reinstate bio-based support in the DM multipath target (done with the idea that fast storage like NVMe over Fabrics could benefit) -- while preserving support for request_fn and blk-mq request-based DM mpath - SCSI and DM multipath persistent reservation fixes that were coordinated with Martin Petersen. - the DM raid target saw the most extensive change this cycle; it now provides reshape and takeover support (by layering ontop of the corresponding MD capabilities) - DAX support for DM core and the linear, stripe and error targets - a DM thin-provisioning block discard vs allocation race fix that addresses potential for corruption - a stable fix for DM verity-fec's block calculation during decode - a few cleanups and fixes to DM core and various targets * tag 'dm-4.8-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm: (73 commits) dm: allow bio-based table to be upgraded to bio-based with DAX support dm snap: add fake origin_direct_access dm stripe: add DAX support dm error: add DAX support dm linear: add DAX support dm: add infrastructure for DAX support dm thin: fix a race condition between discarding and provisioning a block dm btree: fix a bug in dm_btree_find_next_single() dm raid: fix random optimal_io_size for raid0 dm raid: address checkpatch.pl complaints dm: call PR reserve/unreserve on each underlying device sd: don't use the ALL_TG_PT bit for reservations dm: fix second blk_delay_queue() parameter to be in msec units not jiffies dm raid: change logical functions to actually return bool dm raid: use rdev_for_each in status dm raid: use rs->raid_disks to avoid memory leaks on free dm raid: support delta_disks for raid1, fix table output dm raid: enhance reshape check and factor out reshape setup dm raid: allow resize during recovery dm raid: fix rs_is_recovering() to allow for lvextend ...
2016-07-21dm snap: add fake origin_direct_accessToshi Kani1-0/+8
dax-capable mapped-device is marked as DM_TYPE_DAX_BIO_BASED, which supports both dax and bio-based operations. dm-snap needs to work with dax-capable device when bio-based operation is used. Add fake origin_direct_access() to origin device so that its origin device is also marked as DM_TYPE_DAX_BIO_BASED for dax-capable device. This allows to extend target's DM table. dm-snap works normally when bio-based operation is used. dm-snap does not support dax operation, and mount with dax option to a target device or snapshot device fails. Signed-off-by: Toshi Kani <toshi.kani@hpe.com> Cc: Mike Snitzer <snitzer@redhat.com> Cc: Alasdair Kergon <agk@redhat.com> Cc: Dan Williams <dan.j.williams@intel.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2016-07-21block: get rid of bio_rw and READAChristoph Hellwig1-6/+7
These two are confusing leftover of the old world order, combining values of the REQ_OP_ and REQ_ namespaces. For callers that don't special case we mostly just replace bi_rw with bio_data_dir or op_is_write, except for the few cases where a switch over the REQ_OP_ values makes more sense. Any check for READA is replaced with an explicit check for REQ_RAHEAD. Also remove the READA alias for REQ_RAHEAD. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de> Reviewed-by: Mike Christie <mchristi@redhat.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2016-06-07block, drivers, fs: rename REQ_FLUSH to REQ_PREFLUSHMike Christie1-3/+3
To avoid confusion between REQ_OP_FLUSH, which is handled by request_fn drivers, and upper layers requesting the block layer perform a flush sequence along with possibly a WRITE, this patch renames REQ_FLUSH to REQ_PREFLUSH. Signed-off-by: Mike Christie <mchristi@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Hannes Reinecke <hare@suse.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2016-03-11dm snapshot: disallow the COW and origin devices from being identicalDingXiang1-0/+9
Otherwise loading a "snapshot" table using the same device for the origin and COW devices, e.g.: echo "0 20971520 snapshot 253:3 253:3 P 8" | dmsetup create snap will trigger: BUG: unable to handle kernel NULL pointer dereference at 0000000000000098 [ 1958.979934] IP: [<ffffffffa040efba>] dm_exception_store_set_chunk_size+0x7a/0x110 [dm_snapshot] [ 1958.989655] PGD 0 [ 1958.991903] Oops: 0000 [#1] SMP ... [ 1959.059647] CPU: 9 PID: 3556 Comm: dmsetup Tainted: G IO 4.5.0-rc5.snitm+ #150 ... [ 1959.083517] task: ffff8800b9660c80 ti: ffff88032a954000 task.ti: ffff88032a954000 [ 1959.091865] RIP: 0010:[<ffffffffa040efba>] [<ffffffffa040efba>] dm_exception_store_set_chunk_size+0x7a/0x110 [dm_snapshot] [ 1959.104295] RSP: 0018:ffff88032a957b30 EFLAGS: 00010246 [ 1959.110219] RAX: 0000000000000000 RBX: 0000000000000008 RCX: 0000000000000001 [ 1959.118180] RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffff880329334a00 [ 1959.126141] RBP: ffff88032a957b50 R08: 0000000000000000 R09: 0000000000000001 [ 1959.134102] R10: 000000000000000a R11: f000000000000000 R12: ffff880330884d80 [ 1959.142061] R13: 0000000000000008 R14: ffffc90001c13088 R15: ffff880330884d80 [ 1959.150021] FS: 00007f8926ba3840(0000) GS:ffff880333440000(0000) knlGS:0000000000000000 [ 1959.159047] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 1959.165456] CR2: 0000000000000098 CR3: 000000032f48b000 CR4: 00000000000006e0 [ 1959.173415] Stack: [ 1959.175656] ffffc90001c13040 ffff880329334a00 ffff880330884ed0 ffff88032a957bdc [ 1959.183946] ffff88032a957bb8 ffffffffa040f225 ffff880329334a30 ffff880300000000 [ 1959.192233] ffffffffa04133e0 ffff880329334b30 0000000830884d58 00000000569c58cf [ 1959.200521] Call Trace: [ 1959.203248] [<ffffffffa040f225>] dm_exception_store_create+0x1d5/0x240 [dm_snapshot] [ 1959.211986] [<ffffffffa040d310>] snapshot_ctr+0x140/0x630 [dm_snapshot] [ 1959.219469] [<ffffffffa0005c44>] ? dm_split_args+0x64/0x150 [dm_mod] [ 1959.226656] [<ffffffffa0005ea7>] dm_table_add_target+0x177/0x440 [dm_mod] [ 1959.234328] [<ffffffffa0009203>] table_load+0x143/0x370 [dm_mod] [ 1959.241129] [<ffffffffa00090c0>] ? retrieve_status+0x1b0/0x1b0 [dm_mod] [ 1959.248607] [<ffffffffa0009e35>] ctl_ioctl+0x255/0x4d0 [dm_mod] [ 1959.255307] [<ffffffff813304e2>] ? memzero_explicit+0x12/0x20 [ 1959.261816] [<ffffffffa000a0c3>] dm_ctl_ioctl+0x13/0x20 [dm_mod] [ 1959.268615] [<ffffffff81215eb6>] do_vfs_ioctl+0xa6/0x5c0 [ 1959.274637] [<ffffffff81120d2f>] ? __audit_syscall_entry+0xaf/0x100 [ 1959.281726] [<ffffffff81003176>] ? do_audit_syscall_entry+0x66/0x70 [ 1959.288814] [<ffffffff81216449>] SyS_ioctl+0x79/0x90 [ 1959.294450] [<ffffffff8167e4ae>] entry_SYSCALL_64_fastpath+0x12/0x71 ... [ 1959.323277] RIP [<ffffffffa040efba>] dm_exception_store_set_chunk_size+0x7a/0x110 [dm_snapshot] [ 1959.333090] RSP <ffff88032a957b30> [ 1959.336978] CR2: 0000000000000098 [ 1959.344121] ---[ end trace b049991ccad1169e ]--- Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1195899 Cc: stable@vger.kernel.org Signed-off-by: Ding Xiang <dingxiang@huawei.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2016-02-23dm: rename target's per_bio_data_size to per_io_data_sizeMike Snitzer1-1/+1
Request-based DM will also make use of per_bio_data_size. Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2016-01-09dm snapshot: fix hung bios when copy error occursMikulas Patocka1-15/+5
When there is an error copying a chunk dm-snapshot can incorrectly hold associated bios indefinitely, resulting in hung IO. The function copy_callback sets pe->error if there was error copying the chunk, and then calls complete_exception. complete_exception calls pending_complete on error, otherwise it calls commit_exception with commit_callback (and commit_callback calls complete_exception). The persistent exception store (dm-snap-persistent.c) assumes that calls to prepare_exception and commit_exception are paired. persistent_prepare_exception increases ps->pending_count and persistent_commit_exception decreases it. If there is a copy error, persistent_prepare_exception is called but persistent_commit_exception is not. This results in the variable ps->pending_count never returning to zero and that causes some pending exceptions (and their associated bios) to be held forever. Fix this by unconditionally calling commit_exception regardless of whether the copy was successful. A new "valid" parameter is added to commit_exception -- when the copy fails this parameter is set to zero so that the chunk that failed to copy (and all following chunks) is not recorded in the snapshot store. Also, remove commit_callback now that it is merely a wrapper around pending_complete. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Cc: stable@vger.kernel.org
2015-12-10dm: don't save and restore bi_privateMikulas Patocka1-5/+1
Device mapper used the field bi_private to point to dm_target_io. However, since kernel 3.15, the bi_private field is unused, and so the targets do not need to save and restore this field. This patch removes code that saves and restores bi_private from dm-cache, dm-snapshot and dm-verity. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2015-10-09dm snapshot: add new persistent store option to support overflowMike Snitzer1-5/+9
Commit 76c44f6d80 introduced the possibly for "Overflow" to be reported by the snapshot device's status. Older userspace (e.g. lvm2) does not handle the "Overflow" status response. Fix this incompatibility by requiring newer userspace code, that can cope with "Overflow", request the persistent store with overflow support by using "PO" (Persistent with Overflow) for the snapshot store type. Reported-by: Zdenek Kabelac <zkabelac@redhat.com> Fixes: 76c44f6d80 ("dm snapshot: don't invalidate on-disk image on snapshot write overflow") Reviewed-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2015-09-03Merge tag 'dm-4.3-changes' of ↵Linus Torvalds1-4/+16
git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm Pull device mapper update from Mike Snitzer: - a couple small cleanups in dm-cache, dm-verity, persistent-data's dm-btree, and DM core. - a 4.1-stable fix for dm-cache that fixes the leaking of deferred bio prison cells - a 4.2-stable fix that adds feature reporting for the dm-stats features added in 4.2 - improve DM-snapshot to not invalidate the on-disk snapshot if snapshot device write overflow occurs; but a write overflow triggered through the origin device will still invalidate the snapshot. - optimize DM-thinp's async discard submission a bit now that late bio splitting has been included in block core. - switch DM-cache's SMQ policy lock from using a mutex to a spinlock; improves performance on very low latency devices (eg. NVMe SSD). - document DM RAID 4/5/6's discard support [ I did not pull the slab changes, which weren't appropriate for this tree, and weren't obviously the right thing to do anyway. At the very least they need some discussion and explanation before getting merged. Because not pulling the actual tagged commit but doing a partial pull instead, this merge commit thus also obviously is missing the git signature from the original tag ] * tag 'dm-4.3-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm: dm cache: fix use after freeing migrations dm cache: small cleanups related to deferred prison cell cleanup dm cache: fix leaking of deferred bio prison cells dm raid: document RAID 4/5/6 discard support dm stats: report precise_timestamps and histogram in @stats_list output dm thin: optimize async discard submission dm snapshot: don't invalidate on-disk image on snapshot write overflow dm: remove unlikely() before IS_ERR() dm: do not override error code returned from dm_get_device() dm: test return value for DM_MAPIO_SUBMITTED dm verity: remove unused mempool dm cache: move wake_waker() from free_migrations() to where it is needed dm btree remove: remove unused function get_nr_entries() dm btree: remove unused "dm_block_t root" parameter in btree_split_sibling() dm cache policy smq: change the mutex to a spinlock
2015-08-13block: kill merge_bvec_fn() completelyKent Overstreet1-15/+0
As generic_make_request() is now able to handle arbitrarily sized bios, it's no longer necessary for each individual block driver to define its own ->merge_bvec_fn() callback. Remove every invocation completely. Cc: Jens Axboe <axboe@kernel.dk> Cc: Lars Ellenberg <drbd-dev@lists.linbit.com> Cc: drbd-user@lists.linbit.com Cc: Jiri Kosina <jkosina@suse.cz> Cc: Yehuda Sadeh <yehuda@inktank.com> Cc: Sage Weil <sage@inktank.com> Cc: Alex Elder <elder@kernel.org> Cc: ceph-devel@vger.kernel.org Cc: Alasdair Kergon <agk@redhat.com> Cc: Mike Snitzer <snitzer@redhat.com> Cc: dm-devel@redhat.com Cc: Neil Brown <neilb@suse.de> Cc: linux-raid@vger.kernel.org Cc: Christoph Hellwig <hch@infradead.org> Cc: "Martin K. Petersen" <martin.petersen@oracle.com> Acked-by: NeilBrown <neilb@suse.de> (for the 'md' bits) Acked-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com> [dpark: also remove ->merge_bvec_fn() in dm-thin as well as dm-era-target, and resolve merge conflicts] Signed-off-by: Dongsu Park <dpark@posteo.net> Signed-off-by: Ming Lin <ming.l@ssi.samsung.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-08-12dm snapshot: don't invalidate on-disk image on snapshot write overflowMikulas Patocka1-4/+16
When the snapshot overflows because of a write to the origin, the on-disk image has to be invalidated. However, when the snapshot overflows because of a write to the snapshot, the on-disk image doesn't have to be invalidated. Change the behavior so that the on-disk image is not invalidated in this case. When the snapshot overflows, the variable snapshot_overflowed is set. All writes to the snapshot are disallowed to minimize filesystem corruption - this condition is cleared when the snapshot is deactivated and activated. The user can extend the overflowed snapshot, deactivate and activate it again, run fsck (if journaling filesystem is not used) mount it and recover the data. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2015-07-29block: add a bi_error field to struct bioChristoph Hellwig1-3/+3
Currently we have two different ways to signal an I/O error on a BIO: (1) by clearing the BIO_UPTODATE flag (2) by returning a Linux errno value to the bi_end_io callback The first one has the drawback of only communicating a single possible error (-EIO), and the second one has the drawback of not beeing persistent when bios are queued up, and are not passed along from child to parent bio in the ever more popular chaining scenario. Having both mechanisms available has the additional drawback of utterly confusing driver authors and introducing bugs where various I/O submitters only deal with one of them, and the others have to add boilerplate code to deal with both kinds of error returns. So add a new bi_error field to store an errno value directly in struct bio and remove the existing mechanisms to clean all this up. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: NeilBrown <neilb@suse.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-22block: remove management of bi_remaining when restoring original bi_end_ioMike Snitzer1-1/+0
Commit c4cf5261 ("bio: skip atomic inc/dec of ->bi_remaining for non-chains") regressed all existing callers that followed this pattern: 1) saving a bio's original bi_end_io 2) wiring up an intermediate bi_end_io 3) restoring the original bi_end_io from intermediate bi_end_io 4) calling bio_endio() to execute the restored original bi_end_io The regression was due to BIO_CHAIN only ever getting set if bio_inc_remaining() is called. For the above pattern it isn't set until step 3 above (step 2 would've needed to establish BIO_CHAIN). As such the first bio_endio(), in step 2 above, never decremented __bi_remaining before calling the intermediate bi_end_io -- leaving __bi_remaining with the value 1 instead of 0. When bio_inc_remaining() occurred during step 3 it brought it to a value of 2. When the second bio_endio() was called, in step 4 above, it should've called the original bi_end_io but it didn't because there was an extra reference that wasn't dropped (due to atomic operations being optimized away since BIO_CHAIN wasn't set upfront). Fix this issue by removing the __bi_remaining management complexity for all callers that use the above pattern -- bio_chain() is the only interface that _needs_ to be concerned with __bi_remaining. For the above pattern callers just expect the bi_end_io they set to get called! Remove bio_endio_nodec() and also remove all bio_inc_remaining() calls that aren't associated with the bio_chain() interface. Also, the bio_inc_remaining() interface has been moved local to bio.c. Fixes: c4cf5261 ("bio: skip atomic inc/dec of ->bi_remaining for non-chains") Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-05bio: skip atomic inc/dec of ->bi_remaining for non-chainsJens Axboe1-1/+1
Struct bio has an atomic ref count for chained bio's, and we use this to know when to end IO on the bio. However, most bio's are not chained, so we don't need to always introduce this atomic operation as part of ending IO. Add a helper to elevate the bi_remaining count, and flag the bio as now actually needing the decrement at end_io time. Rename the field to __bi_remaining to catch any current users of this doing the incrementing manually. For high IOPS workloads, this reduces the overhead of bio_endio() substantially. Tested-by: Robert Elliott <elliott@hp.com> Acked-by: Kent Overstreet <kent.overstreet@gmail.com> Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-02-27dm snapshot: suspend merging snapshot when doing exception handoverMikulas Patocka1-6/+29
The "dm snapshot: suspend origin when doing exception handover" commit fixed a exception store handover bug associated with pending exceptions to the "snapshot-origin" target. However, a similar problem exists in snapshot merging. When snapshot merging is in progress, we use the target "snapshot-merge" instead of "snapshot-origin". Consequently, during exception store handover, we must find the snapshot-merge target and suspend its associated mapped_device. To avoid lockdep warnings, the target must be suspended and resumed without holding _origins_lock. Introduce a dm_hold() function that grabs a reference on a mapped_device, but unlike dm_get(), it doesn't crash if the device has the DMF_FREEING flag set, it returns an error in this case. In snapshot_resume() we grab the reference to the origin device using dm_hold() while holding _origins_lock (_origins_lock guarantees that the device won't disappear). Then we release _origins_lock, suspend the device and grab _origins_lock again. NOTE to stable@ people: When backporting to kernels 3.18 and older, use dm_internal_suspend and dm_internal_resume instead of dm_internal_suspend_fast and dm_internal_resume_fast. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Cc: stable@vger.kernel.org
2015-02-27dm snapshot: suspend origin when doing exception handoverMikulas Patocka1-9/+84
In the function snapshot_resume we perform exception store handover. If there is another active snapshot target, the exception store is moved from this target to the target that is being resumed. The problem is that if there is some pending exception, it will point to an incorrect exception store after that handover, causing a crash due to dm-snap-persistent.c:get_exception()'s BUG_ON. This bug can be triggered by repeatedly changing snapshot permissions with "lvchange -p r" and "lvchange -p rw" while there are writes on the associated origin device. To fix this bug, we must suspend the origin device when doing the exception store handover to make sure that there are no pending exceptions: - introduce _origin_hash that keeps track of dm_origin structures. - introduce functions __lookup_dm_origin, __insert_dm_origin and __remove_dm_origin that manipulate the origin hash. - modify snapshot_resume so that it calls dm_internal_suspend_fast() and dm_internal_resume_fast() on the origin device. NOTE to stable@ people: When backporting to kernels 3.12-3.18, use dm_internal_suspend and dm_internal_resume instead of dm_internal_suspend_fast and dm_internal_resume_fast. When backporting to kernels older than 3.12, you need to pick functions dm_internal_suspend and dm_internal_resume from the commit fd2ed4d252701d3bbed4cd3e3d267ad469bb832a. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Cc: stable@vger.kernel.org
2015-02-18dm snapshot: fix a possible invalid memory access on unloadMikulas Patocka1-2/+2
When the snapshot target is unloaded, snapshot_dtr() waits until pending_exceptions_count drops to zero. Then, it destroys the snapshot. Therefore, the function that decrements pending_exceptions_count should not touch the snapshot structure after the decrement. pending_complete() calls free_pending_exception(), which decrements pending_exceptions_count, and then it performs up_write(&s->lock) and it calls retry_origin_bios() which dereferences s->origin. These two memory accesses to the fields of the snapshot may touch the dm_snapshot struture after it is freed. This patch moves the call to free_pending_exception() to the end of pending_complete(), so that the snapshot will not be destroyed while pending_complete() is in progress. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Cc: stable@vger.kernel.org
2014-07-16sched: Remove proliferation of wait_on_bit() action functionsNeilBrown1-9/+1
The current "wait_on_bit" interface requires an 'action' function to be provided which does the actual waiting. There are over 20 such functions, many of them identical. Most cases can be satisfied by one of just two functions, one which uses io_schedule() and one which just uses schedule(). So: Rename wait_on_bit and wait_on_bit_lock to wait_on_bit_action and wait_on_bit_lock_action to make it explicit that they need an action function. Introduce new wait_on_bit{,_lock} and wait_on_bit{,_lock}_io which are *not* given an action function but implicitly use a standard one. The decision to error-out if a signal is pending is now made based on the 'mode' argument rather than being encoded in the action function. All instances of the old wait_on_bit and wait_on_bit_lock which can use the new version have been changed accordingly and their action functions have been discarded. wait_on_bit{_lock} does not return any specific error code in the event of a signal so the caller must check for non-zero and interpolate their own error code as appropriate. The wait_on_bit() call in __fscache_wait_on_invalidate() was ambiguous as it specified TASK_UNINTERRUPTIBLE but used fscache_wait_bit_interruptible as an action function. David Howells confirms this should be uniformly "uninterruptible" The main remaining user of wait_on_bit{,_lock}_action is NFS which needs to use a freezer-aware schedule() call. A comment in fs/gfs2/glock.c notes that having multiple 'action' functions is useful as they display differently in the 'wchan' field of 'ps'. (and /proc/$PID/wchan). As the new bit_wait{,_io} functions are tagged "__sched", they will not show up at all, but something higher in the stack. So the distinction will still be visible, only with different function names (gds2_glock_wait versus gfs2_glock_dq_wait in the gfs2/glock.c case). Since first version of this patch (against 3.15) two new action functions appeared, on in NFS and one in CIFS. CIFS also now uses an action function that makes the same freezer aware schedule call as NFS. Signed-off-by: NeilBrown <neilb@suse.de> Acked-by: David Howells <dhowells@redhat.com> (fscache, keys) Acked-by: Steven Whitehouse <swhiteho@redhat.com> (gfs2) Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Steve French <sfrench@samba.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/20140707051603.28027.72349.stgit@notabene.brown Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-06-13Merge tag 'dm-3.16-changes' of ↵Linus Torvalds1-19/+48
git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm Pull device mapper updates from Mike Snitzer: "This pull request is later than I'd have liked because I was waiting for some performance data to help finally justify sending the long-standing dm-crypt cpu scalability improvements upstream. Unfortunately we came up short, so those dm-crypt changes will continue to wait, but it seems we're not far off. . Add dm_accept_partial_bio interface to DM core to allow DM targets to only process a portion of a bio, the remainder being sent in the next bio. This enables the old dm snapshot-origin target to only split write bios on chunk boundaries, read bios are now sent to the origin device unchanged. . Add DM core support for disabling WRITE SAME if the underlying SCSI layer disables it due to command failure. . Reduce lock contention in DM's bio-prison. . A few small cleanups and fixes to dm-thin and dm-era" * tag 'dm-3.16-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm: dm thin: update discard_granularity to reflect the thin-pool blocksize dm bio prison: implement per bucket locking in the dm_bio_prison hash table dm: remove symbol export for dm_set_device_limits dm: disable WRITE SAME if it fails dm era: check for a non-NULL metadata object before closing it dm thin: return ENOSPC instead of EIO when error_if_no_space enabled dm thin: cleanup noflush_work to use a proper completion dm snapshot: do not split read bios sent to snapshot-origin target dm snapshot: allocate a per-target structure for snapshot-origin target dm: introduce dm_accept_partial_bio dm: change sector_count member in clone_info from sector_t to unsigned
2014-06-03dm snapshot: do not split read bios sent to snapshot-origin targetMikulas Patocka1-3/+15
Change the snapshot-origin target so that only write bios are split on chunk boundary. Read bios are passed unchanged to the underlying device, so they don't have to be split. Later, we could change the target so that it accepts a larger write bio if it spans an area that is completely covered by snapshot exceptions. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2014-06-03dm snapshot: allocate a per-target structure for snapshot-origin targetMikulas Patocka1-18/+35
Allocate a per-target dm_origin structure. This is a prerequisite for the next commit ("dm snapshot: do not split read bios sent to snapshot-origin target") which adds a new member to this structure. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2014-04-18arch: Mass conversion of smp_mb__*()Peter Zijlstra1-2/+2
Mostly scripted conversion of the smp_mb__* barriers. Signed-off-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Link: http://lkml.kernel.org/n/tip-55dhyhocezdw1dg7u19hmh1u@git.kernel.org Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: linux-arch@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-01-30Merge branch 'for-3.14/core' of git://git.kernel.dk/linux-blockLinus Torvalds1-9/+10
Pull core block IO changes from Jens Axboe: "The major piece in here is the immutable bio_ve series from Kent, the rest is fairly minor. It was supposed to go in last round, but various issues pushed it to this release instead. The pull request contains: - Various smaller blk-mq fixes from different folks. Nothing major here, just minor fixes and cleanups. - Fix for a memory leak in the error path in the block ioctl code from Christian Engelmayer. - Header export fix from CaiZhiyong. - Finally the immutable biovec changes from Kent Overstreet. This enables some nice future work on making arbitrarily sized bios possible, and splitting more efficient. Related fixes to immutable bio_vecs: - dm-cache immutable fixup from Mike Snitzer. - btrfs immutable fixup from Muthu Kumar. - bio-integrity fix from Nic Bellinger, which is also going to stable" * 'for-3.14/core' of git://git.kernel.dk/linux-block: (44 commits) xtensa: fixup simdisk driver to work with immutable bio_vecs block/blk-mq-cpu.c: use hotcpu_notifier() blk-mq: for_each_* macro correctness block: Fix memory leak in rw_copy_check_uvector() handling bio-integrity: Fix bio_integrity_verify segment start bug block: remove unrelated header files and export symbol blk-mq: uses page->list incorrectly blk-mq: use __smp_call_function_single directly btrfs: fix missing increment of bi_remaining Revert "block: Warn and free bio if bi_end_io is not set" block: Warn and free bio if bi_end_io is not set blk-mq: fix initializing request's start time block: blk-mq: don't export blk_mq_free_queue() block: blk-mq: make blk_sync_queue support mq block: blk-mq: support draining mq queue dm cache: increment bi_remaining when bi_end_io is restored block: fixup for generic bio chaining block: Really silence spurious compiler warnings block: Silence spurious compiler warnings block: Kill bio_pair_split() ...
2014-01-14dm snapshot: use GFP_KERNEL when initializing exceptionsMikulas Patocka1-5/+5
The list of initial exceptions is loaded in the target constructor. We are allowed to allocate memory with GFP_KERNEL at this point. So, change alloc_completed_exception to use GFP_KERNEL when being called from the constructor. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
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