This patch implements gradual cleanup for dm-writecache - if the block is stored in the cache for too long, it will be written to the underlying device and cleaned up.
The patch adds a new option "max_age" that specified the maximum age of a block in milliseconds. Signed-off-by: Mikulas Patocka <[email protected]> --- drivers/md/dm-writecache.c | 34 +++++++++++++++++++++++++++++++++- 1 file changed, 33 insertions(+), 1 deletion(-) Index: linux-2.6/drivers/md/dm-writecache.c =================================================================== --- linux-2.6.orig/drivers/md/dm-writecache.c 2020-02-23 18:16:22.000000000 +0100 +++ linux-2.6/drivers/md/dm-writecache.c 2020-02-23 18:16:22.000000000 +0100 @@ -26,6 +26,7 @@ #define AUTOCOMMIT_BLOCKS_SSD 65536 #define AUTOCOMMIT_BLOCKS_PMEM 64 #define AUTOCOMMIT_MSEC 1000 +#define MAX_AGE_DIV 16 #define BITMAP_GRANULARITY 65536 #if BITMAP_GRANULARITY < PAGE_SIZE @@ -88,6 +89,7 @@ struct wc_entry { :47 #endif ; + unsigned long age; #ifdef DM_WRITECACHE_HANDLE_HARDWARE_ERRORS uint64_t original_sector; uint64_t seq_count; @@ -119,6 +121,7 @@ struct dm_writecache { size_t writeback_size; size_t freelist_high_watermark; size_t freelist_low_watermark; + unsigned long max_age; unsigned uncommitted_blocks; unsigned autocommit_blocks; @@ -130,6 +133,8 @@ struct dm_writecache { struct timer_list autocommit_timer; struct wait_queue_head freelist_wait; + struct timer_list max_age_timer; + atomic_t bio_in_progress[2]; struct wait_queue_head bio_in_progress_wait[2]; @@ -597,6 +602,7 @@ static void writecache_insert_entry(stru rb_link_node(&ins->rb_node, parent, node); rb_insert_color(&ins->rb_node, &wc->tree); list_add(&ins->lru, &wc->lru); + ins->age = jiffies; } static void writecache_unlink(struct dm_writecache *wc, struct wc_entry *e) @@ -632,6 +638,15 @@ static inline void writecache_verify_wat queue_work(wc->writeback_wq, &wc->writeback_work); } +static void writecache_max_age_timer(struct timer_list *t) +{ + struct dm_writecache *wc = from_timer(wc, t, max_age_timer); + if (!dm_suspended(wc->ti) && !writecache_has_error(wc)) { + queue_work(wc->writeback_wq, &wc->writeback_work); + mod_timer(&wc->max_age_timer, jiffies + wc->max_age / MAX_AGE_DIV); + } +} + static struct wc_entry *writecache_pop_from_freelist(struct dm_writecache *wc, sector_t expected_sector) { struct wc_entry *e; @@ -838,6 +853,7 @@ static void writecache_suspend(struct dm bool flush_on_suspend; del_timer_sync(&wc->autocommit_timer); + del_timer_sync(&wc->max_age_timer); wc_lock(wc); writecache_flush(wc); @@ -974,6 +990,9 @@ erase_this: writecache_verify_watermark(wc); + if (wc->max_age != -1UL) + mod_timer(&wc->max_age_timer, jiffies + wc->max_age / MAX_AGE_DIV); + wc_unlock(wc); } @@ -1661,7 +1680,8 @@ restart: wbl.size = 0; while (!list_empty(&wc->lru) && (wc->writeback_all || - wc->freelist_size + wc->writeback_size <= wc->freelist_low_watermark)) { + wc->freelist_size + wc->writeback_size <= wc->freelist_low_watermark || + jiffies - container_of(wc->lru.prev, struct wc_entry, lru)->age >= wc->max_age - wc->max_age / MAX_AGE_DIV)) { n_walked++; if (unlikely(n_walked > WRITEBACK_LATENCY) && @@ -1924,9 +1944,11 @@ static int writecache_ctr(struct dm_targ wc->ti = ti; mutex_init(&wc->lock); + wc->max_age = -1UL; writecache_poison_lists(wc); init_waitqueue_head(&wc->freelist_wait); timer_setup(&wc->autocommit_timer, writecache_autocommit_timer, 0); + timer_setup(&wc->max_age_timer, writecache_max_age_timer, 0); for (i = 0; i < 2; i++) { atomic_set(&wc->bio_in_progress[i], 0); @@ -2100,6 +2122,14 @@ static int writecache_ctr(struct dm_targ goto invalid_optional; wc->autocommit_jiffies = msecs_to_jiffies(autocommit_msecs); wc->autocommit_time_set = true; + } else if (!strcasecmp(string, "max_age") && opt_params >= 1) { + unsigned max_age_msecs; + string = dm_shift_arg(&as), opt_params--; + if (sscanf(string, "%u%c", &max_age_msecs, &dummy) != 1) + goto invalid_optional; + if (max_age_msecs > 86400000) + goto invalid_optional; + wc->max_age = msecs_to_jiffies(max_age_msecs); } else if (!strcasecmp(string, "cleaner")) { wc->cleaner = true; } else if (!strcasecmp(string, "fua")) { @@ -2361,6 +2391,8 @@ static void writecache_status(struct dm_ DMEMIT(" autocommit_blocks %u", wc->autocommit_blocks); if (wc->autocommit_time_set) DMEMIT(" autocommit_time %u", jiffies_to_msecs(wc->autocommit_jiffies)); + if (wc->max_age != -1UL) + DMEMIT(" max_age %u", jiffies_to_msecs(wc->max_age)); if (wc->cleaner) DMEMIT(" cleaner"); if (wc->writeback_fua_set) -- dm-devel mailing list [email protected] https://www.redhat.com/mailman/listinfo/dm-devel
