From b73c67c2cbb0004e6da9720a167fe42e31f7a6e8 Mon Sep 17 00:00:00 2001 From: Damien Le Moal Date: Mon, 8 May 2017 16:40:51 -0700 Subject: [PATCH] dm kcopyd: add sequential write feature When copyying blocks to host-managed zoned block devices, writes must be sequential. However, dm_kcopyd_copy() does not guarantee this as writes are issued in the completion order of reads, and reads may complete out of order despite being issued sequentially. Fix this by introducing the DM_KCOPYD_WRITE_SEQ feature flag. This can be specified when calling dm_kcopyd_copy() and should be set automatically if one of the destinations is a host-managed zoned block device. For a split job, the master job maintains the write position at which writes must be issued. This is checked with the pop() function which is modified to not return any write I/O sub job that is not at the correct write position. When DM_KCOPYD_WRITE_SEQ is specified for a job, errors cannot be ignored and the flag DM_KCOPYD_IGNORE_ERROR is ignored, even if specified by the user. Signed-off-by: Damien Le Moal Reviewed-by: Hannes Reinecke Reviewed-by: Bart Van Assche Signed-off-by: Mike Snitzer --- drivers/md/dm-kcopyd.c | 65 +++++++++++++++++++++++++++++++++++++-- include/linux/dm-kcopyd.h | 1 + 2 files changed, 64 insertions(+), 2 deletions(-) diff --git a/drivers/md/dm-kcopyd.c b/drivers/md/dm-kcopyd.c index f85846741d50..cf2c67e35eaf 100644 --- a/drivers/md/dm-kcopyd.c +++ b/drivers/md/dm-kcopyd.c @@ -356,6 +356,7 @@ struct kcopyd_job { struct mutex lock; atomic_t sub_jobs; sector_t progress; + sector_t write_offset; struct kcopyd_job *master_job; }; @@ -386,6 +387,31 @@ void dm_kcopyd_exit(void) * Functions to push and pop a job onto the head of a given job * list. */ +static struct kcopyd_job *pop_io_job(struct list_head *jobs, + struct dm_kcopyd_client *kc) +{ + struct kcopyd_job *job; + + /* + * For I/O jobs, pop any read, any write without sequential write + * constraint and sequential writes that are at the right position. + */ + list_for_each_entry(job, jobs, list) { + if (job->rw == READ || !test_bit(DM_KCOPYD_WRITE_SEQ, &job->flags)) { + list_del(&job->list); + return job; + } + + if (job->write_offset == job->master_job->write_offset) { + job->master_job->write_offset += job->source.count; + list_del(&job->list); + return job; + } + } + + return NULL; +} + static struct kcopyd_job *pop(struct list_head *jobs, struct dm_kcopyd_client *kc) { @@ -395,8 +421,12 @@ static struct kcopyd_job *pop(struct list_head *jobs, spin_lock_irqsave(&kc->job_lock, flags); if (!list_empty(jobs)) { - job = list_entry(jobs->next, struct kcopyd_job, list); - list_del(&job->list); + if (jobs == &kc->io_jobs) + job = pop_io_job(jobs, kc); + else { + job = list_entry(jobs->next, struct kcopyd_job, list); + list_del(&job->list); + } } spin_unlock_irqrestore(&kc->job_lock, flags); @@ -506,6 +536,14 @@ static int run_io_job(struct kcopyd_job *job) .client = job->kc->io_client, }; + /* + * If we need to write sequentially and some reads or writes failed, + * no point in continuing. + */ + if (test_bit(DM_KCOPYD_WRITE_SEQ, &job->flags) && + job->master_job->write_err) + return -EIO; + io_job_start(job->kc->throttle); if (job->rw == READ) @@ -655,6 +693,7 @@ static void segment_complete(int read_err, unsigned long write_err, int i; *sub_job = *job; + sub_job->write_offset = progress; sub_job->source.sector += progress; sub_job->source.count = count; @@ -723,6 +762,27 @@ int dm_kcopyd_copy(struct dm_kcopyd_client *kc, struct dm_io_region *from, job->num_dests = num_dests; memcpy(&job->dests, dests, sizeof(*dests) * num_dests); + /* + * If one of the destination is a host-managed zoned block device, + * we need to write sequentially. If one of the destination is a + * host-aware device, then leave it to the caller to choose what to do. + */ + if (!test_bit(DM_KCOPYD_WRITE_SEQ, &job->flags)) { + for (i = 0; i < job->num_dests; i++) { + if (bdev_zoned_model(dests[i].bdev) == BLK_ZONED_HM) { + set_bit(DM_KCOPYD_WRITE_SEQ, &job->flags); + break; + } + } + } + + /* + * If we need to write sequentially, errors cannot be ignored. + */ + if (test_bit(DM_KCOPYD_WRITE_SEQ, &job->flags) && + test_bit(DM_KCOPYD_IGNORE_ERROR, &job->flags)) + clear_bit(DM_KCOPYD_IGNORE_ERROR, &job->flags); + if (from) { job->source = *from; job->pages = NULL; @@ -746,6 +806,7 @@ int dm_kcopyd_copy(struct dm_kcopyd_client *kc, struct dm_io_region *from, job->fn = fn; job->context = context; job->master_job = job; + job->write_offset = 0; if (job->source.count <= SUB_JOB_SIZE) dispatch_job(job); diff --git a/include/linux/dm-kcopyd.h b/include/linux/dm-kcopyd.h index f486d636b82e..cfac8588ed56 100644 --- a/include/linux/dm-kcopyd.h +++ b/include/linux/dm-kcopyd.h @@ -20,6 +20,7 @@ #define DM_KCOPYD_MAX_REGIONS 8 #define DM_KCOPYD_IGNORE_ERROR 1 +#define DM_KCOPYD_WRITE_SEQ 2 struct dm_kcopyd_throttle { unsigned throttle; -- 2.20.1