kernel/linux.git/drivers/md/md.h, branch v5.6.17

md: introduce a new struct for IO serialization

2020-01-13T19:44:10+00:00

Obviously, IO serialization could cause the degradation of performance a lot. In order to reduce the degradation, so a rb interval tree is added in raid1 to speed up the check of collision. So, a rb root is needed in md_rdev, then abstract all the serialize related members to a new struct (serial_in_rdev), embed it into md_rdev. Of course, we need to free the struct if it is not needed anymore, so rdev/rdevs_uninit_serial are added accordingly. And they should be called when destroty memory pool or can't alloc memory. And we need to consider to call mddev_destroy_serial_pool in case serialize_policy/write-behind is disabled, bitmap is destroyed or in __md_stop_writes. Signed-off-by: Guoqing Jiang Signed-off-by: Song Liu

md: add serialize_policy sysfs node for raid1

2020-01-13T19:44:09+00:00

With the new sysfs node, we can use it to control if raid1 array wants io serialization or not. So mddev_create_serial_pool and mddev_destroy_serial_pool are called in serialize_policy_store to enable or disable the serialization. Signed-off-by: Guoqing Jiang Signed-off-by: Song Liu

md: prepare for enable raid1 io serialization

2020-01-13T19:44:09+00:00

1. The related resources (spin_lock, list and waitqueue) are needed for address raid1 reorder overlap issue too, in this case, rdev is set to NULL for mddev_create/destroy_serial_pool which implies all rdevs need to handle these resources. And also add "is_suspend" to mddev_destroy_serial_pool since it will be called under suspended situation, which also makes both create and destroy pool have same arguments. 2. Introduce rdevs_init_serial which is called if raid1 io serialization is enabled since all rdevs need to init related stuffs. 3. rdev_init_serial and clear_bit(CollisionCheck, &rdev->flags) should be called between suspend and resume. No need to export mddev_create_serial_pool since it is only called in md-mod module. Signed-off-by: Guoqing Jiang Signed-off-by: Song Liu

md: rename wb stuffs

2020-01-13T19:44:09+00:00

Previously, wb_info_pool and wb_list stuffs are introduced to address potential data inconsistence issue for write behind device. Now rename them to serial related name, since the same mechanism will be used to address reorder overlap write issue for raid1. Signed-off-by: Guoqing Jiang Signed-off-by: Song Liu

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

2019-10-24T22:22:40+00:00

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

md raid0/linear: Mark array as 'broken' and fail BIOs if a member is gone

2019-09-03T21:49:28+00:00

Currently md raid0/linear are not provided with any mechanism to validate if an array member got removed or failed. The driver keeps sending BIOs regardless of the state of array members, and kernel shows state 'clean' in the 'array_state' sysfs attribute. This leads to the following situation: if a raid0/linear array member is removed and the array is mounted, some user writing to this array won't realize that errors are happening unless they check dmesg or perform one fsync per written file. Despite udev signaling the member device is gone, 'mdadm' cannot issue the STOP_ARRAY ioctl successfully, given the array is mounted. In other words, no -EIO is returned and writes (except direct ones) appear normal. Meaning the user might think the wrote data is correctly stored in the array, but instead garbage was written given that raid0 does stripping (and so, it requires all its members to be working in order to not corrupt data). For md/linear, writes to the available members will work fine, but if the writes go to the missing member(s), it'll cause a file corruption situation, whereas the portion of the writes to the missing devices aren't written effectively. This patch changes this behavior: we check if the block device's gendisk is UP when submitting the BIO to the array member, and if it isn't, we flag the md device as MD_BROKEN and fail subsequent I/Os to that device; a read request to the array requiring data from a valid member is still completed. While flagging the device as MD_BROKEN, we also show a rate-limited warning in the kernel log. A new array state 'broken' was added too: it mimics the state 'clean' in every aspect, being useful only to distinguish if the array has some member missing. We rely on the MD_BROKEN flag to put the array in the 'broken' state. This state cannot be written in 'array_state' as it just shows one or more members of the array are missing but acts like 'clean', it wouldn't make sense to write it. With this patch, the filesystem reacts much faster to the event of missing array member: after some I/O errors, ext4 for instance aborts the journal and prevents corruption. Without this change, we're able to keep writing in the disk and after a machine reboot, e2fsck shows some severe fs errors that demand fixing. This patch was tested in ext4 and xfs filesystems, and requires a 'mdadm' counterpart to handle the 'broken' state. Cc: Song Liu Reviewed-by: NeilBrown Signed-off-by: Guilherme G. Piccoli Signed-off-by: Song Liu

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

2019-08-27T19:36:37+00:00

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

md: allow last device to be forcibly removed from RAID1/RAID10.

2019-08-07T17:25:02+00:00

When the 'last' device in a RAID1 or RAID10 reports an error, we do not mark it as failed. This would serve little purpose as there is no risk of losing data beyond that which is obviously lost (as there is with RAID5), and there could be other sectors on the device which are readable, and only readable from this device. This in general this maximises access to data. However the current implementation also stops an admin from removing the last device by direct action. This is rarely useful, but in many case is not harmful and can make automation easier by removing special cases. Also, if an attempt to write metadata fails the device must be marked as faulty, else an infinite loop will result, attempting to update the metadata on all non-faulty devices. So add 'fail_last_dev' member to 'struct mddev', then we can bypasses the 'last disk' checks for RAID1 and RAID10, and control the behavior per array by change sysfs node. Signed-off-by: NeilBrown [add sysfs node for fail_last_dev by Guoqing] Signed-off-by: Guoqing Jiang Signed-off-by: Song Liu

md: introduce mddev_create/destroy_wb_pool for the change of member device

2019-06-20T23:36:00+00:00

Previously, we called rdev_init_wb to avoid potential data inconsistency when array is created. Now, we need to call the function and create mempool if a device is added or just be flaged as "writemostly". So mddev_create_wb_pool is introduced and called accordingly. And for safety reason, we mark implicit GFP_NOIO allocation scope for create mempool during mddev_suspend/mddev_resume. And mempool should be removed conversely after remove a member device or its's "writemostly" flag, which is done by call mddev_destroy_wb_pool. Reviewed-by: NeilBrown Signed-off-by: Guoqing Jiang Signed-off-by: Song Liu

md/raid1: fix potential data inconsistency issue with write behind device

2019-06-20T23:35:59+00:00

For write-behind mode, we think write IO is complete once it has reached all the non-writemostly devices. It works fine for single queue devices. But for multiqueue device, if there are lots of IOs come from upper layer, then the write-behind device could issue those IOs to different queues, depends on the each queue's delay, so there is no guarantee that those IOs can arrive in order. To address the issue, we need to check the collision among write behind IOs, we can only continue without collision, otherwise wait for the completion of previous collisioned IO. And WBCollision is introduced for multiqueue device which is worked under write-behind mode. But this patch doesn't handle below cases which could have the data inconsistency issue as well, these cases will be handled in later patches. 1. modify max_write_behind by write backlog node. 2. add or remove array's bitmap dynamically. 3. the change of member disk. Reviewed-by: NeilBrown Signed-off-by: Guoqing Jiang Signed-off-by: Song Liu