[Devel] [RFC PATCH vz9 v6 37/62] dm-ploop: convert md page rw lock to spin lock
Andrey Zhadchenko
andrey.zhadchenko at virtuozzo.com
Fri Dec 13 16:09:15 MSK 2024
On 12/5/24 22:56, Alexander Atanasov wrote:
> Prepare locking for threads. Some operations require to lock bat data
> (see next patch) and in some cases we need to lock md page while hodling
> bat spin lock but we can not take sleeping lock while holding a spin lock.
> To address this use a spin lock for md pages instead of rwlock.
As far as I know, rwlock is a spinlock subtype. So this should not be
the problem.
If you insist on spinlocking, please do merge this patch to the one that
implements md_lock
>
> https://virtuozzo.atlassian.net/browse/VSTOR-91821
> Signed-off-by: Alexander Atanasov <alexander.atanasov at virtuozzo.com>
> ---
> drivers/md/dm-ploop-bat.c | 6 +++---
> drivers/md/dm-ploop-cmd.c | 24 ++++++++++++------------
> drivers/md/dm-ploop-map.c | 23 +++++++++++------------
> drivers/md/dm-ploop.h | 6 +++---
> 4 files changed, 29 insertions(+), 30 deletions(-)
>
> diff --git a/drivers/md/dm-ploop-bat.c b/drivers/md/dm-ploop-bat.c
> index a6202720927f..efdc82a59abf 100644
> --- a/drivers/md/dm-ploop-bat.c
> +++ b/drivers/md/dm-ploop-bat.c
> @@ -88,7 +88,7 @@ static struct md_page *ploop_alloc_md_page(u32 id)
> md->page = page;
> md->kmpage = kmap(page);
> md->id = id;
> - rwlock_init(&md->lock);
> + spin_lock_init(&md->md_lock);
> return md;
> err_page:
> kfree(levels);
> @@ -143,13 +143,13 @@ bool ploop_try_update_bat_entry(struct ploop *ploop, u32 clu, u8 level, u32 dst_
>
> clu = ploop_bat_clu_idx_in_page(clu); /* relative offset */
>
> - write_lock_irqsave(&md->lock, flags);
> + spin_lock_irqsave(&md->md_lock, flags);
> if (READ_ONCE(md->bat_levels[clu]) == level) {
> bat_entries = md->kmpage;
> WRITE_ONCE(bat_entries[clu], dst_clu);
> ret = true;
> }
> - write_unlock_irqrestore(&md->lock, flags);
> + spin_unlock_irqrestore(&md->md_lock, flags);
>
> return ret;
> }
> diff --git a/drivers/md/dm-ploop-cmd.c b/drivers/md/dm-ploop-cmd.c
> index d4408cba5f0d..017250328ea3 100644
> --- a/drivers/md/dm-ploop-cmd.c
> +++ b/drivers/md/dm-ploop-cmd.c
> @@ -46,7 +46,7 @@ static void ploop_advance_holes_bitmap(struct ploop *ploop,
> ploop_init_be_iter(ploop, md->id, &i, &end);
> bat_entries = md->kmpage;
>
> - read_lock_irqsave(&md->lock, flags);
> + spin_lock(&md->md_lock);
> for (; i <= end; i++) {
> if (!ploop_md_page_cluster_is_in_top_delta(ploop, md, i))
> continue;
> @@ -57,7 +57,7 @@ static void ploop_advance_holes_bitmap(struct ploop *ploop,
> ploop_hole_clear_bit(dst_clu, ploop);
> }
> }
> - read_unlock_irqrestore(&md->lock, flags);
> + spin_unlock(&md->md_lock);
> }
> write_unlock_irq(&ploop->bat_rwlock);
> }
> @@ -169,7 +169,7 @@ static u32 ploop_find_bat_entry(struct ploop *ploop, u32 dst_clu, bool *is_locke
> ploop_init_be_iter(ploop, md->id, &i, &end);
> bat_entries = md->kmpage;
>
> - read_lock_irqsave(&md->lock, flags);
> + spin_lock_irqsave(&md->md_lock, flags);
> for (; i <= end; i++) {
> if (READ_ONCE(bat_entries[i]) != dst_clu)
> continue;
> @@ -178,7 +178,7 @@ static u32 ploop_find_bat_entry(struct ploop *ploop, u32 dst_clu, bool *is_locke
> break;
> }
> }
> - read_unlock_irqrestore(&md->lock, flags);
> + spin_unlock_irqrestore(&md->md_lock, flags);
> if (clu != UINT_MAX)
> break;
> }
> @@ -727,8 +727,8 @@ static void notify_delta_merged(struct ploop *ploop, u8 level,
> bat_entries = md->kmpage;
> d_bat_entries = d_md->kmpage;
>
> - write_lock_irqsave(&md->lock, flags);
> - write_lock(&d_md->lock);
> + spin_lock_irqsave(&md->md_lock, flags);
> + spin_lock(&d_md->md_lock);
>
> for (; i <= end; i++) {
> clu = ploop_page_clu_idx_to_bat_clu(md->id, i);
> @@ -763,8 +763,8 @@ static void notify_delta_merged(struct ploop *ploop, u8 level,
> WRITE_ONCE(md->bat_levels[i], level);
> }
>
> - write_unlock(&d_md->lock);
> - write_unlock_irqrestore(&md->lock, flags);
> + spin_unlock(&d_md->md_lock);
> + spin_unlock_irqrestore(&md->md_lock, flags);
>
> if (stop)
> break;
> @@ -1055,8 +1055,8 @@ static int ploop_check_delta_before_flip(struct ploop *ploop, struct file *file)
> init_be_iter(nr_be, md->id, &i, &end);
> d_bat_entries = d_md->kmpage;
>
> - read_lock_irqsave(&md->lock, flags);
> - read_lock(&d_md->lock);
> + spin_lock_irqsave(&md->md_lock, flags);
> + spin_lock(&d_md->md_lock);
> for (; i <= end; i++) {
> if (ploop_md_page_cluster_is_in_top_delta(ploop, md, i) &&
> d_bat_entries[i] != BAT_ENTRY_NONE) {
> @@ -1065,8 +1065,8 @@ static int ploop_check_delta_before_flip(struct ploop *ploop, struct file *file)
> goto unmap;
> }
> }
> - read_unlock(&d_md->lock);
> - read_unlock_irqrestore(&md->lock, flags);
> + spin_unlock(&d_md->md_lock);
> + spin_unlock_irqrestore(&md->md_lock, flags);
>
> clu = ploop_page_clu_idx_to_bat_clu(md->id, i);
> if (clu == nr_be - 1) {
> diff --git a/drivers/md/dm-ploop-map.c b/drivers/md/dm-ploop-map.c
> index 3a741bb9d2db..2a6ff9e2996b 100644
> --- a/drivers/md/dm-ploop-map.c
> +++ b/drivers/md/dm-ploop-map.c
> @@ -387,13 +387,13 @@ static bool ploop_delay_if_md_busy(struct ploop *ploop, struct md_page *md,
> WARN_ON_ONCE(!list_empty(&pio->list));
>
> /* lock protects piwb */
> - read_lock_irqsave(&md->lock, flags);
> + spin_lock_irqsave(&md->md_lock, flags);
> piwb = md->piwb;
> if (piwb && (piwb->type != type || test_bit(MD_WRITEBACK, &md->status))) {
> llist_add((struct llist_node *)(&pio->list), &md->wait_llist);
> busy = true;
> }
> - read_unlock_irqrestore(&md->lock, flags);
> + spin_unlock_irqrestore(&md->md_lock, flags);
>
> return busy;
> }
> @@ -807,7 +807,7 @@ static void ploop_advance_local_after_bat_wb(struct ploop *ploop,
>
> dst_clu = piwb->kmpage;
>
> - write_lock_irqsave(&md->lock, flags);
> + spin_lock(&md->md_lock);
> if (piwb->type == PIWB_TYPE_ALLOC)
> goto skip_apply;
>
> @@ -832,7 +832,7 @@ static void ploop_advance_local_after_bat_wb(struct ploop *ploop,
> WARN_ON_ONCE(!test_bit(MD_WRITEBACK, &md->status));
> clear_bit(MD_WRITEBACK, &md->status);
> md->piwb = NULL;
> - write_unlock_irqrestore(&md->lock, flags);
> + spin_unlock(&md->md_lock);
>
> wait_llist_pending = llist_del_all(&md->wait_llist);
> if (wait_llist_pending) {
> @@ -957,15 +957,14 @@ static int ploop_prepare_bat_update(struct ploop *ploop, struct md_page *md,
>
> bat_entries = md->kmpage;
>
> - write_lock_irq(&md->lock);
> + spin_lock_irq(&md->md_lock);
> + WARN_ON_ONCE(md->piwb);
> md->piwb = piwb;
> piwb->md = md;
> - write_unlock_irq(&md->lock);
>
> piwb->page_id = page_id;
> to = piwb->kmpage;
>
> - read_lock_irq(&md->lock);
> memcpy((void *)to, bat_entries, PAGE_SIZE);
>
> /* Absolute number of first index in page (negative for page#0) */
> @@ -990,7 +989,7 @@ static int ploop_prepare_bat_update(struct ploop *ploop, struct md_page *md,
> if (clu == BAT_ENTRY_NONE || level < ploop_top_level(ploop))
> to[i] = 0;
> }
> - read_unlock_irq(&md->lock);
> + spin_unlock_irq(&md->md_lock);
>
> if (is_last_page) {
> /* Fill tail of page with 0 */
> @@ -1010,10 +1009,10 @@ void ploop_break_bat_update(struct ploop *ploop, struct md_page *md)
> struct ploop_index_wb *piwb;
> unsigned long flags;
>
> - write_lock_irqsave(&md->lock, flags);
> + spin_lock_irqsave(&md->md_lock, flags);
> piwb = md->piwb;
> md->piwb = NULL;
> - write_unlock_irqrestore(&md->lock, flags);
> + spin_unlock_irqrestore(&md->md_lock, flags);
>
> ploop_free_piwb(piwb);
> }
> @@ -1440,11 +1439,11 @@ static void ploop_submit_cow_index_wb(struct ploop_cow *cow)
> WARN_ON(to[clu]);
> WRITE_ONCE(to[clu], cow->dst_clu);
>
> - write_lock_irqsave(&md->lock, flags);
> + spin_lock_irqsave(&md->md_lock, flags);
> to = md->kmpage;
> WRITE_ONCE(to[clu], cow->dst_clu);
> WRITE_ONCE(md->bat_levels[clu], ploop_top_level(ploop));
> - write_unlock_irqrestore(&md->lock, flags);
> + spin_unlock_irqrestore(&md->md_lock, flags);
>
> ploop_md_up_prio(ploop, md);
>
> diff --git a/drivers/md/dm-ploop.h b/drivers/md/dm-ploop.h
> index 3c632eab37d7..42a1b4759d75 100644
> --- a/drivers/md/dm-ploop.h
> +++ b/drivers/md/dm-ploop.h
> @@ -128,7 +128,7 @@ struct md_page {
> struct list_head wb_link;
> struct ploop_index_wb *piwb;
>
> - rwlock_t lock;
> + spinlock_t md_lock;
>
> unsigned long dirty_timeout;
> };
> @@ -447,7 +447,7 @@ static inline u32 ploop_bat_entries(struct ploop *ploop, u32 clu,
> /* Cluster index related to the page[page_id] start */
> clu = ploop_bat_clu_idx_in_page(clu);
>
> - read_lock_irqsave(&md->lock, flags);
> + spin_lock_irqsave(&md->md_lock, flags);
> if (bat_level)
> *bat_level = READ_ONCE(md->bat_levels[clu]);
> if (md_ret)
> @@ -455,7 +455,7 @@ static inline u32 ploop_bat_entries(struct ploop *ploop, u32 clu,
>
> bat_entries = md->kmpage;
> dst_clu = READ_ONCE(bat_entries[clu]);
> - read_unlock_irqrestore(&md->lock, flags);
> + spin_unlock_irqrestore(&md->md_lock, flags);
>
> return dst_clu;
> }
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