linux/drivers/md/linear.c, branch v4.11

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

2017-02-24T22:42:19Z

Pull md updates from Shaohua Li: "Mainly fixes bugs and improves performance: - Improve scalability for raid1 from Coly - Improve raid5-cache read performance, disk efficiency and IO pattern from Song and me - Fix a race condition of disk hotplug for linear from Coly - A few cleanup patches from Ming and Byungchul - Fix a memory leak from Neil - Fix WRITE SAME IO failure from me - Add doc for raid5-cache from me" * 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/shli/md: (23 commits) md/raid1: fix write behind issues introduced by bio_clone_bioset_partial md/raid1: handle flush request correctly md/linear: shutup lockdep warnning md/raid1: fix a use-after-free bug RAID1: avoid unnecessary spin locks in I/O barrier code RAID1: a new I/O barrier implementation to remove resync window md/raid5: Don't reinvent the wheel but use existing llist API md: fast clone bio in bio_clone_mddev() md: remove unnecessary check on mddev md/raid1: use bio_clone_bioset_partial() in case of write behind md: fail if mddev->bio_set can't be created block: introduce bio_clone_bioset_partial() md: disable WRITE SAME if it fails in underlayer disks md/raid5-cache: exclude reclaiming stripes in reclaim check md/raid5-cache: stripe reclaim only counts valid stripes MD: add doc for raid5-cache Documentation: move MD related doc into a separate dir md: ensure md devices are freed before module is unloaded. md/r5cache: improve journal device efficiency md/r5cache: enable chunk_aligned_read with write back cache ...

md/linear: shutup lockdep warnning

2017-02-23T19:59:42Z

Commit 03a9e24(md linear: fix a race between linear_add() and linear_congested()) introduces the warnning. Acked-by: Coly Li Signed-off-by: Shaohua Li

md: disable WRITE SAME if it fails in underlayer disks

2017-02-14T03:24:16Z

This makes md do the same thing as dm for write same IO failure. Please see 7eee4ae(dm: disable WRITE SAME if it fails) for details why we need this. We did a little bit different than dm. Instead of disabling writesame in the first IO error, we disable it till next writesame IO coming after the first IO error. This way we don't need to clone a bio. Also reported here: https://bugzilla.kernel.org/show_bug.cgi?id=118581 Suggested-by: NeilBrown Acked-by: NeilBrown Signed-off-by: Shaohua Li

md linear: fix a race between linear_add() and linear_congested()

2017-02-13T17:17:50Z

Recently I receive a bug report that on Linux v3.0 based kerenl, hot add disk to a md linear device causes kernel crash at linear_congested(). From the crash image analysis, I find in linear_congested(), mddev->raid_disks contains value N, but conf->disks[] only has N-1 pointers available. Then a NULL pointer deference crashes the kernel. There is a race between linear_add() and linear_congested(), RCU stuffs used in these two functions cannot avoid the race. Since Linuv v4.0 RCU code is replaced by introducing mddev_suspend(). After checking the upstream code, it seems linear_congested() is not called in generic_make_request() code patch, so mddev_suspend() cannot provent it from being called. The possible race still exists. Here I explain how the race still exists in current code. For a machine has many CPUs, on one CPU, linear_add() is called to add a hard disk to a md linear device; at the same time on other CPU, linear_congested() is called to detect whether this md linear device is congested before issuing an I/O request onto it. Now I use a possible code execution time sequence to demo how the possible race happens, seq linear_add() linear_congested() 0 conf=mddev->private 1 oldconf=mddev->private 2 mddev->raid_disks++ 3 for (i=0; iraid_disks;i++) 4 bdev_get_queue(conf->disks[i].rdev->bdev) 5 mddev->private=newconf In linear_add() mddev->raid_disks is increased in time seq 2, and on another CPU in linear_congested() the for-loop iterates conf->disks[i] by the increased mddev->raid_disks in time seq 3,4. But conf with one more element (which is a pointer to struct dev_info type) to conf->disks[] is not updated yet, accessing its structure member in time seq 4 will cause a NULL pointer deference fault. To fix this race, there are 2 parts of modification in the patch, 1) Add 'int raid_disks' in struct linear_conf, as a copy of mddev->raid_disks. It is initialized in linear_conf(), always being consistent with pointers number of 'struct dev_info disks[]'. When iterating conf->disks[] in linear_congested(), use conf->raid_disks to replace mddev->raid_disks in the for-loop, then NULL pointer deference will not happen again. 2) RCU stuffs are back again, and use kfree_rcu() in linear_add() to free oldconf memory. Because oldconf may be referenced as mddev->private in linear_congested(), kfree_rcu() makes sure that its memory will not be released until no one uses it any more. Also some code comments are added in this patch, to make this modification to be easier understandable. This patch can be applied for kernels since v4.0 after commit: 3be260cc18f8 ("md/linear: remove rcu protections in favour of suspend/resume"). But this bug is reported on Linux v3.0 based kernel, for people who maintain kernels before Linux v4.0, they need to do some back back port to this patch. Changelog: - V3: add 'int raid_disks' in struct linear_conf, and use kfree_rcu() to replace rcu_call() in linear_add(). - v2: add RCU stuffs by suggestion from Shaohua and Neil. - v1: initial effort. Signed-off-by: Coly Li Cc: Shaohua Li Cc: Neil Brown Cc: stable@vger.kernel.org Signed-off-by: Shaohua Li

block: Use pointer to backing_dev_info from request_queue

2017-02-02T15:20:48Z

We will want to have struct backing_dev_info allocated separately from struct request_queue. As the first step add pointer to backing_dev_info to request_queue and convert all users touching it. No functional changes in this patch. Reviewed-by: Christoph Hellwig Signed-off-by: Jan Kara Signed-off-by: Jens Axboe

md: add block tracing for bio_remapping

2016-11-18T17:32:50Z

The block tracing infrastructure (accessed with blktrace/blkparse) supports the tracing of mapping bios from one device to another. This is currently used when a bio in a partition is mapped to the whole device, when bios are mapped by dm, and for mapping in md/raid5. Other md personalities do not include this tracing yet, so add it. When a read-error is detected we redirect the request to a different device. This could justifiably be seen as a new mapping for the originial bio, or a secondary mapping for the bio that errors. This patch uses the second option. When md is used under dm-raid, the mappings are not traced as we do not have access to the block device number of the parent. Signed-off-by: NeilBrown Signed-off-by: Shaohua Li

md/linear: replace printk() with pr_*()

2016-11-07T23:08:21Z

Signed-off-by: NeilBrown Signed-off-by: Shaohua Li

block: rename bio bi_rw to bi_opf

2016-08-07T20:41:02Z

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

block, drivers, fs: rename REQ_FLUSH to REQ_PREFLUSH

2016-06-07T19:41:38Z

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 Reviewed-by: Christoph Hellwig Reviewed-by: Hannes Reinecke Signed-off-by: Jens Axboe

md: use bio op accessors

2016-06-07T19:41:38Z

Separate the op from the rq_flag_bits and have md set/get the bio using bio_set_op_attrs/bio_op. Signed-off-by: Mike Christie Reviewed-by: Christoph Hellwig Reviewed-by: Hannes Reinecke Signed-off-by: Jens Axboe