kernel/linux.git/drivers/md/md.h, branch v4.19.112

md: improve handling of bio with REQ_PREFLUSH in md_flush_request()

2019-12-17T19:34:55+00:00

commit 775d78319f1ceb32be8eb3b1202ccdc60e9cb7f1 upstream. If pers->make_request fails in md_flush_request(), the bio is lost. To fix this, pass back a bool to indicate if the original make_request call should continue to handle the I/O and instead of assuming the flush logic will push it to completion. Convert md_flush_request to return a bool and no longer calls the raid driver's make_request function. If the return is true, then the md flush logic has or will complete the bio and the md make_request call is done. If false, then the md make_request function needs to keep processing like it is a normal bio. Let the original call to md_handle_request handle any need to retry sending the bio to the raid driver's make_request function should it be needed. Also mark md_flush_request and the make_request function pointer as __must_check to issue warnings should these critical return values be ignored. Fixes: 2bc13b83e629 ("md: batch flush requests.") Cc: stable@vger.kernel.org # # v4.19+ Cc: NeilBrown Signed-off-by: David Jeffery Reviewed-by: Xiao Ni Signed-off-by: Song Liu Signed-off-by: Greg Kroah-Hartman

md: don't report active array_state until after revalidate_disk() completes.

2019-10-05T11:10:10+00:00

commit 9d4b45d6af442237560d0bb5502a012baa5234b7 upstream. Until revalidate_disk() has completed, the size of a new md array will appear to be zero. So we shouldn't report, through array_state, that the array is active until that time. udev rules check array_state to see if the array is ready. As soon as it appear to be zero, fsck can be run. If it find the size to be zero, it will fail. So add a new flag to provide an interlock between do_md_run() and array_state_show(). This flag is set while do_md_run() is active and it prevents array_state_show() from reporting that the array is active. Before do_md_run() is called, ->pers will be NULL so array is definitely not active. After do_md_run() is called, revalidate_disk() will have run and the array will be completely ready. We also move various sysfs_notify*() calls out of md_run() into do_md_run() after MD_NOT_READY is cleared. This ensure the information is ready before the notification is sent. Prior to v4.12, array_state_show() was called with the mddev->reconfig_mutex held, which provided exclusion with do_md_run(). Note that MD_NOT_READY cleared twice. This is deliberate to cover both success and error paths with minimal noise. Fixes: b7b17c9b67e5 ("md: remove mddev_lock() from md_attr_show()") Cc: stable@vger.kernel.org (v4.12++) Signed-off-by: NeilBrown Signed-off-by: Song Liu Signed-off-by: Greg Kroah-Hartman

md: batch flush requests.

2019-05-25T16:23:25+00:00

commit 2bc13b83e6298486371761de503faeffd15b7534 upstream. Currently if many flush requests are submitted to an md device is quick succession, they are serialized and can take a long to process them all. We don't really need to call flush all those times - a single flush call can satisfy all requests submitted before it started. So keep track of when the current flush started and when it finished, allow any pending flush that was requested before the flush started to complete without waiting any more. Test results from Xiao: Test is done on a raid10 device which is created by 4 SSDs. The tool is dbench. 1. The latest linux stable kernel Operation Count AvgLat MaxLat -------------------------------------------------- Deltree 768 10.509 78.305 Flush 2078376 0.013 10.094 Close 21787697 0.019 18.821 LockX 96580 0.007 3.184 Mkdir 384 0.008 0.062 Rename 1255883 0.191 23.534 ReadX 46495589 0.020 14.230 WriteX 14790591 7.123 60.706 Unlink 5989118 0.440 54.551 UnlockX 96580 0.005 2.736 FIND_FIRST 10393845 0.042 12.079 SET_FILE_INFORMATION 2415558 0.129 10.088 QUERY_FILE_INFORMATION 4711725 0.005 8.462 QUERY_PATH_INFORMATION 26883327 0.032 21.715 QUERY_FS_INFORMATION 4929409 0.010 8.238 NTCreateX 29660080 0.100 53.268 Throughput 1034.88 MB/sec (sync open) 128 clients 128 procs max_latency=60.712 ms 2. With patch1 "Revert "MD: fix lock contention for flush bios"" Operation Count AvgLat MaxLat -------------------------------------------------- Deltree 256 8.326 36.761 Flush 693291 3.974 180.269 Close 7266404 0.009 36.929 LockX 32160 0.006 0.840 Mkdir 128 0.008 0.021 Rename 418755 0.063 29.945 ReadX 15498708 0.007 7.216 WriteX 4932310 22.482 267.928 Unlink 1997557 0.109 47.553 UnlockX 32160 0.004 1.110 FIND_FIRST 3465791 0.036 7.320 SET_FILE_INFORMATION 805825 0.015 1.561 QUERY_FILE_INFORMATION 1570950 0.005 2.403 QUERY_PATH_INFORMATION 8965483 0.013 14.277 QUERY_FS_INFORMATION 1643626 0.009 3.314 NTCreateX 9892174 0.061 41.278 Throughput 345.009 MB/sec (sync open) 128 clients 128 procs max_latency=267.939 m 3. With patch1 and patch2 Operation Count AvgLat MaxLat -------------------------------------------------- Deltree 768 9.570 54.588 Flush 2061354 0.666 15.102 Close 21604811 0.012 25.697 LockX 95770 0.007 1.424 Mkdir 384 0.008 0.053 Rename 1245411 0.096 12.263 ReadX 46103198 0.011 12.116 WriteX 14667988 7.375 60.069 Unlink 5938936 0.173 30.905 UnlockX 95770 0.005 4.147 FIND_FIRST 10306407 0.041 11.715 SET_FILE_INFORMATION 2395987 0.048 7.640 QUERY_FILE_INFORMATION 4672371 0.005 9.291 QUERY_PATH_INFORMATION 26656735 0.018 19.719 QUERY_FS_INFORMATION 4887940 0.010 7.654 NTCreateX 29410811 0.059 28.551 Throughput 1026.21 MB/sec (sync open) 128 clients 128 procs max_latency=60.075 ms Cc: # v4.19+ Tested-by: Xiao Ni Signed-off-by: NeilBrown Signed-off-by: Song Liu Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

Revert "MD: fix lock contention for flush bios"

2019-05-25T16:23:25+00:00

commit 4bc034d35377196c854236133b07730a777c4aba upstream. This reverts commit 5a409b4f56d50b212334f338cb8465d65550cd85. This patch has two problems. 1/ it make multiple calls to submit_bio() from inside a make_request_fn. The bios thus submitted will be queued on current->bio_list and not submitted immediately. As the bios are allocated from a mempool, this can theoretically result in a deadlock - all the pool of requests could be in various ->bio_list queues and a subsequent mempool_alloc could block waiting for one of them to be released. 2/ It aims to handle a case when there are many concurrent flush requests. It handles this by submitting many requests in parallel - all of which are identical and so most of which do nothing useful. It would be more efficient to just send one lower-level request, but allow that to satisfy multiple upper-level requests. Fixes: 5a409b4f56d5 ("MD: fix lock contention for flush bios") Cc: # v4.19+ Tested-by: Xiao Ni Signed-off-by: NeilBrown Signed-off-by: Song Liu Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

md-cluster: show array's status more accurate

2018-07-05T18:17:01+00:00

When resync or recovery is happening in one node, other nodes don't show the appropriate info now. For example, when create an array in master node without "--assume-clean", then assemble the array in slave nodes, you can see "resync=PENDING" when read /proc/mdstat in slave nodes. However, the info is confusing since "PENDING" status is introduced for start array in read-only mode. We introduce RESYNCING_REMOTE flag to indicate that resync thread is running in remote node. The flags is set when node receive RESYNCING msg. And we clear the REMOTE flag in following cases: 1. resync or recover is finished in master node, which means slaves receive msg with both lo and hi are set to 0. 2. node continues resync/recovery in recover_bitmaps. 3. when resync_finish is called. Then we show accurate information in status_resync by check REMOTE flags and with other conditions. Signed-off-by: Guoqing Jiang Reviewed-by: NeilBrown Signed-off-by: Shaohua Li

Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/shli/md

2018-06-09T19:01:36+00:00

Pull MD updates from Shaohua Li: "A few fixes of MD for this merge window. Mostly bug fixes: - raid5 stripe batch fix from Amy - Read error handling for raid1 FailFast device from Gioh - raid10 recovery NULL pointer dereference fix from Guoqing - Support write hint for raid5 stripe cache from Mariusz - Fixes for device hot add/remove from Neil and Yufen - Improve flush bio scalability from Xiao" * 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/shli/md: MD: fix lock contention for flush bios md/raid5: Assigning NULL to sh->batch_head before testing bit R5_Overlap of a stripe md/raid1: add error handling of read error from FailFast device md: fix NULL dereference of mddev->pers in remove_and_add_spares() raid5: copy write hint from origin bio to stripe md: fix two problems with setting the "re-add" device state. raid10: check bio in r10buf_pool_free to void NULL pointer dereference md: fix an error code format and remove unsed bio_sector

md: convert to bioset_init()/mempool_init()

2018-05-30T21:33:32+00:00

Convert md to embedded bio sets. Signed-off-by: Kent Overstreet Signed-off-by: Jens Axboe

MD: fix lock contention for flush bios

2018-05-21T16:30:26+00:00

There is a lock contention when there are many processes which send flush bios to md device. eg. Create many lvs on one raid device and mkfs.xfs on each lv. Now it just can handle flush request sequentially. It needs to wait mddev->flush_bio to be NULL, otherwise get mddev->lock. This patch remove mddev->flush_bio and handle flush bio asynchronously. I did a test with command dbench -s 128 -t 300. This is the test result: =================Without the patch============================ Operation Count AvgLat MaxLat -------------------------------------------------- Flush 11165 167.595 5879.560 Close 107469 1.391 2231.094 LockX 384 0.003 0.019 Rename 5944 2.141 1856.001 ReadX 208121 0.003 0.074 WriteX 98259 1925.402 15204.895 Unlink 25198 13.264 3457.268 UnlockX 384 0.001 0.009 FIND_FIRST 47111 0.012 0.076 SET_FILE_INFORMATION 12966 0.007 0.065 QUERY_FILE_INFORMATION 27921 0.004 0.085 QUERY_PATH_INFORMATION 124650 0.005 5.766 QUERY_FS_INFORMATION 22519 0.003 0.053 NTCreateX 141086 4.291 2502.812 Throughput 3.7181 MB/sec (sync open) 128 clients 128 procs max_latency=15204.905 ms =================With the patch============================ Operation Count AvgLat MaxLat -------------------------------------------------- Flush 4500 174.134 406.398 Close 48195 0.060 467.062 LockX 256 0.003 0.029 Rename 2324 0.026 0.360 ReadX 78846 0.004 0.504 WriteX 66832 562.775 1467.037 Unlink 5516 3.665 1141.740 UnlockX 256 0.002 0.019 FIND_FIRST 16428 0.015 0.313 SET_FILE_INFORMATION 6400 0.009 0.520 QUERY_FILE_INFORMATION 17865 0.003 0.089 QUERY_PATH_INFORMATION 47060 0.078 416.299 QUERY_FS_INFORMATION 7024 0.004 0.032 NTCreateX 55921 0.854 1141.452 Throughput 11.744 MB/sec (sync open) 128 clients 128 procs max_latency=1467.041 ms The test is done on raid1 disk with two rotational disks V5: V4 is more complicated than the version with memory pool. So revert to the memory pool version V4: use address of fbio to do hash to choose free flush info. V3: Shaohua suggests mempool is overkill. In v3 it allocs memory during creating raid device and uses a simple bitmap to record which resource is free. Fix a bug from v2. It should set flush_pending to 1 at first. V2: Neil pointed out two problems. One is counting error problem and another is return value when allocat memory fails. 1. counting error problem This isn't safe. It is only safe to call rdev_dec_pending() on rdevs that you previously called atomic_inc(&rdev->nr_pending); If an rdev was added to the list between the start and end of the flush, this will do something bad. Now it doesn't use bio_chain. It uses specified call back function for each flush bio. 2. Returned on IO error when kmalloc fails is wrong. I use mempool suggested by Neil in V2 3. Fixed some places pointed by Guoqing Suggested-by: Ming Lei Signed-off-by: Xiao Ni Signed-off-by: Shaohua Li

md: fix md_write_start() deadlock w/o metadata devices

2018-02-18T18:11:59+00:00

If no metadata devices are configured on raid1/4/5/6/10 (e.g. via dm-raid), md_write_start() unconditionally waits for superblocks to be written thus deadlocking. Fix introduces mddev->has_superblocks bool, defines it in md_run() and checks for it in md_write_start() to conditionally avoid waiting. Once on it, check for non-existing superblocks in md_super_write(). Link: https://bugzilla.kernel.org/show_bug.cgi?id=198647 Fixes: cc27b0c78c796 ("md: fix deadlock between mddev_suspend() and md_write_start()") Signed-off-by: Heinz Mauelshagen Signed-off-by: Shaohua Li

raid5-ppl: PPL support for disks with write-back cache enabled

2018-01-15T22:29:42+00:00

In order to provide data consistency with PPL for disks with write-back cache enabled all data has to be flushed to disks before next PPL entry. The disks to be flushed are marked in the bitmap. It's modified under a mutex and it's only read after PPL io unit is submitted. A limitation of 64 disks in the array has been introduced to keep data structures and implementation simple. RAID5 arrays with so many disks are not likely due to high risk of multiple disks failure. Such restriction should not be a real life limitation. With write-back cache disabled next PPL entry is submitted when data write for current one completes. Data flush defers next log submission so trigger it when there are no stripes for handling found. As PPL assures all data is flushed to disk at request completion, just acknowledge flush request when PPL is enabled. Signed-off-by: Tomasz Majchrzak Signed-off-by: Shaohua Li