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-rw-r--r--drivers/md/raid5-cache.c171
-rw-r--r--drivers/md/raid5.c20
-rw-r--r--drivers/md/raid5.h1
3 files changed, 168 insertions, 24 deletions
diff --git a/drivers/md/raid5-cache.c b/drivers/md/raid5-cache.c
index 302dea3296ba..76c0e5063f1b 100644
--- a/drivers/md/raid5-cache.c
+++ b/drivers/md/raid5-cache.c
@@ -20,6 +20,7 @@
#include <linux/crc32c.h>
#include <linux/random.h>
#include <linux/kthread.h>
+#include <linux/types.h>
#include "md.h"
#include "raid5.h"
#include "bitmap.h"
@@ -164,9 +165,60 @@ struct r5l_log {
struct work_struct deferred_io_work;
/* to disable write back during in degraded mode */
struct work_struct disable_writeback_work;
+
+ /* to for chunk_aligned_read in writeback mode, details below */
+ spinlock_t tree_lock;
+ struct radix_tree_root big_stripe_tree;
};
/*
+ * Enable chunk_aligned_read() with write back cache.
+ *
+ * Each chunk may contain more than one stripe (for example, a 256kB
+ * chunk contains 64 4kB-page, so this chunk contain 64 stripes). For
+ * chunk_aligned_read, these stripes are grouped into one "big_stripe".
+ * For each big_stripe, we count how many stripes of this big_stripe
+ * are in the write back cache. These data are tracked in a radix tree
+ * (big_stripe_tree). We use radix_tree item pointer as the counter.
+ * r5c_tree_index() is used to calculate keys for the radix tree.
+ *
+ * chunk_aligned_read() calls r5c_big_stripe_cached() to look up
+ * big_stripe of each chunk in the tree. If this big_stripe is in the
+ * tree, chunk_aligned_read() aborts. This look up is protected by
+ * rcu_read_lock().
+ *
+ * It is necessary to remember whether a stripe is counted in
+ * big_stripe_tree. Instead of adding new flag, we reuses existing flags:
+ * STRIPE_R5C_PARTIAL_STRIPE and STRIPE_R5C_FULL_STRIPE. If either of these
+ * two flags are set, the stripe is counted in big_stripe_tree. This
+ * requires moving set_bit(STRIPE_R5C_PARTIAL_STRIPE) to
+ * r5c_try_caching_write(); and moving clear_bit of
+ * STRIPE_R5C_PARTIAL_STRIPE and STRIPE_R5C_FULL_STRIPE to
+ * r5c_finish_stripe_write_out().
+ */
+
+/*
+ * radix tree requests lowest 2 bits of data pointer to be 2b'00.
+ * So it is necessary to left shift the counter by 2 bits before using it
+ * as data pointer of the tree.
+ */
+#define R5C_RADIX_COUNT_SHIFT 2
+
+/*
+ * calculate key for big_stripe_tree
+ *
+ * sect: align_bi->bi_iter.bi_sector or sh->sector
+ */
+static inline sector_t r5c_tree_index(struct r5conf *conf,
+ sector_t sect)
+{
+ sector_t offset;
+
+ offset = sector_div(sect, conf->chunk_sectors);
+ return sect;
+}
+
+/*
* an IO range starts from a meta data block and end at the next meta data
* block. The io unit's the meta data block tracks data/parity followed it. io
* unit is written to log disk with normal write, as we always flush log disk
@@ -412,16 +464,6 @@ void r5c_make_stripe_write_out(struct stripe_head *sh)
if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
atomic_inc(&conf->preread_active_stripes);
-
- if (test_and_clear_bit(STRIPE_R5C_PARTIAL_STRIPE, &sh->state)) {
- BUG_ON(atomic_read(&conf->r5c_cached_partial_stripes) == 0);
- atomic_dec(&conf->r5c_cached_partial_stripes);
- }
-
- if (test_and_clear_bit(STRIPE_R5C_FULL_STRIPE, &sh->state)) {
- BUG_ON(atomic_read(&conf->r5c_cached_full_stripes) == 0);
- atomic_dec(&conf->r5c_cached_full_stripes);
- }
}
static void r5c_handle_data_cached(struct stripe_head *sh)
@@ -2320,6 +2362,10 @@ int r5c_try_caching_write(struct r5conf *conf,
int i;
struct r5dev *dev;
int to_cache = 0;
+ void **pslot;
+ sector_t tree_index;
+ int ret;
+ uintptr_t refcount;
BUG_ON(!r5c_is_writeback(log));
@@ -2364,6 +2410,44 @@ int r5c_try_caching_write(struct r5conf *conf,
}
}
+ /* if the stripe is not counted in big_stripe_tree, add it now */
+ if (!test_bit(STRIPE_R5C_PARTIAL_STRIPE, &sh->state) &&
+ !test_bit(STRIPE_R5C_FULL_STRIPE, &sh->state)) {
+ tree_index = r5c_tree_index(conf, sh->sector);
+ spin_lock(&log->tree_lock);
+ pslot = radix_tree_lookup_slot(&log->big_stripe_tree,
+ tree_index);
+ if (pslot) {
+ refcount = (uintptr_t)radix_tree_deref_slot_protected(
+ pslot, &log->tree_lock) >>
+ R5C_RADIX_COUNT_SHIFT;
+ radix_tree_replace_slot(
+ &log->big_stripe_tree, pslot,
+ (void *)((refcount + 1) << R5C_RADIX_COUNT_SHIFT));
+ } else {
+ /*
+ * this radix_tree_insert can fail safely, so no
+ * need to call radix_tree_preload()
+ */
+ ret = radix_tree_insert(
+ &log->big_stripe_tree, tree_index,
+ (void *)(1 << R5C_RADIX_COUNT_SHIFT));
+ if (ret) {
+ spin_unlock(&log->tree_lock);
+ r5c_make_stripe_write_out(sh);
+ return -EAGAIN;
+ }
+ }
+ spin_unlock(&log->tree_lock);
+
+ /*
+ * set STRIPE_R5C_PARTIAL_STRIPE, this shows the stripe is
+ * counted in the radix tree
+ */
+ set_bit(STRIPE_R5C_PARTIAL_STRIPE, &sh->state);
+ atomic_inc(&conf->r5c_cached_partial_stripes);
+ }
+
for (i = disks; i--; ) {
dev = &sh->dev[i];
if (dev->towrite) {
@@ -2438,17 +2522,20 @@ void r5c_finish_stripe_write_out(struct r5conf *conf,
struct stripe_head *sh,
struct stripe_head_state *s)
{
+ struct r5l_log *log = conf->log;
int i;
int do_wakeup = 0;
+ sector_t tree_index;
+ void **pslot;
+ uintptr_t refcount;
- if (!conf->log ||
- !test_bit(R5_InJournal, &sh->dev[sh->pd_idx].flags))
+ if (!log || !test_bit(R5_InJournal, &sh->dev[sh->pd_idx].flags))
return;
WARN_ON(test_bit(STRIPE_R5C_CACHING, &sh->state));
clear_bit(R5_InJournal, &sh->dev[sh->pd_idx].flags);
- if (conf->log->r5c_journal_mode == R5C_JOURNAL_MODE_WRITE_THROUGH)
+ if (log->r5c_journal_mode == R5C_JOURNAL_MODE_WRITE_THROUGH)
return;
for (i = sh->disks; i--; ) {
@@ -2470,12 +2557,43 @@ void r5c_finish_stripe_write_out(struct r5conf *conf,
if (do_wakeup)
wake_up(&conf->wait_for_overlap);
- spin_lock_irq(&conf->log->stripe_in_journal_lock);
+ spin_lock_irq(&log->stripe_in_journal_lock);
list_del_init(&sh->r5c);
- spin_unlock_irq(&conf->log->stripe_in_journal_lock);
+ spin_unlock_irq(&log->stripe_in_journal_lock);
sh->log_start = MaxSector;
- atomic_dec(&conf->log->stripe_in_journal_count);
- r5c_update_log_state(conf->log);
+
+ atomic_dec(&log->stripe_in_journal_count);
+ r5c_update_log_state(log);
+
+ /* stop counting this stripe in big_stripe_tree */
+ if (test_bit(STRIPE_R5C_PARTIAL_STRIPE, &sh->state) ||
+ test_bit(STRIPE_R5C_FULL_STRIPE, &sh->state)) {
+ tree_index = r5c_tree_index(conf, sh->sector);
+ spin_lock(&log->tree_lock);
+ pslot = radix_tree_lookup_slot(&log->big_stripe_tree,
+ tree_index);
+ BUG_ON(pslot == NULL);
+ refcount = (uintptr_t)radix_tree_deref_slot_protected(
+ pslot, &log->tree_lock) >>
+ R5C_RADIX_COUNT_SHIFT;
+ if (refcount == 1)
+ radix_tree_delete(&log->big_stripe_tree, tree_index);
+ else
+ radix_tree_replace_slot(
+ &log->big_stripe_tree, pslot,
+ (void *)((refcount - 1) << R5C_RADIX_COUNT_SHIFT));
+ spin_unlock(&log->tree_lock);
+ }
+
+ if (test_and_clear_bit(STRIPE_R5C_PARTIAL_STRIPE, &sh->state)) {
+ BUG_ON(atomic_read(&conf->r5c_cached_partial_stripes) == 0);
+ atomic_dec(&conf->r5c_cached_partial_stripes);
+ }
+
+ if (test_and_clear_bit(STRIPE_R5C_FULL_STRIPE, &sh->state)) {
+ BUG_ON(atomic_read(&conf->r5c_cached_full_stripes) == 0);
+ atomic_dec(&conf->r5c_cached_full_stripes);
+ }
}
int
@@ -2535,6 +2653,22 @@ r5c_cache_data(struct r5l_log *log, struct stripe_head *sh,
return 0;
}
+/* check whether this big stripe is in write back cache. */
+bool r5c_big_stripe_cached(struct r5conf *conf, sector_t sect)
+{
+ struct r5l_log *log = conf->log;
+ sector_t tree_index;
+ void *slot;
+
+ if (!log)
+ return false;
+
+ WARN_ON_ONCE(!rcu_read_lock_held());
+ tree_index = r5c_tree_index(conf, sect);
+ slot = radix_tree_lookup(&log->big_stripe_tree, tree_index);
+ return slot != NULL;
+}
+
static int r5l_load_log(struct r5l_log *log)
{
struct md_rdev *rdev = log->rdev;
@@ -2681,6 +2815,9 @@ int r5l_init_log(struct r5conf *conf, struct md_rdev *rdev)
if (!log->meta_pool)
goto out_mempool;
+ spin_lock_init(&log->tree_lock);
+ INIT_RADIX_TREE(&log->big_stripe_tree, GFP_NOWAIT | __GFP_NOWARN);
+
log->reclaim_thread = md_register_thread(r5l_reclaim_thread,
log->rdev->mddev, "reclaim");
if (!log->reclaim_thread)
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 9d744a8961d1..b62f671a93ab 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -281,13 +281,13 @@ static void do_release_stripe(struct r5conf *conf, struct stripe_head *sh,
atomic_dec(&conf->r5c_cached_partial_stripes);
list_add_tail(&sh->lru, &conf->r5c_full_stripe_list);
r5c_check_cached_full_stripe(conf);
- } else {
- /* partial stripe */
- if (!test_and_set_bit(STRIPE_R5C_PARTIAL_STRIPE,
- &sh->state))
- atomic_inc(&conf->r5c_cached_partial_stripes);
+ } else
+ /*
+ * STRIPE_R5C_PARTIAL_STRIPE is set in
+ * r5c_try_caching_write(). No need to
+ * set it again.
+ */
list_add_tail(&sh->lru, &conf->r5c_partial_stripe_list);
- }
}
}
}
@@ -5062,6 +5062,13 @@ static int raid5_read_one_chunk(struct mddev *mddev, struct bio *raid_bio)
rdev->recovery_offset >= end_sector)))
rdev = NULL;
}
+
+ if (r5c_big_stripe_cached(conf, align_bi->bi_iter.bi_sector)) {
+ rcu_read_unlock();
+ bio_put(align_bi);
+ return 0;
+ }
+
if (rdev) {
sector_t first_bad;
int bad_sectors;
@@ -5418,7 +5425,6 @@ static void raid5_make_request(struct mddev *mddev, struct bio * bi)
* data on failed drives.
*/
if (rw == READ && mddev->degraded == 0 &&
- !r5c_is_writeback(conf->log) &&
mddev->reshape_position == MaxSector) {
bi = chunk_aligned_read(mddev, bi);
if (!bi)
diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h
index ebb89bda88f1..c0687df5ba06 100644
--- a/drivers/md/raid5.h
+++ b/drivers/md/raid5.h
@@ -792,4 +792,5 @@ extern void r5c_check_stripe_cache_usage(struct r5conf *conf);
extern void r5c_check_cached_full_stripe(struct r5conf *conf);
extern struct md_sysfs_entry r5c_journal_mode;
extern void r5c_update_on_rdev_error(struct mddev *mddev);
+extern bool r5c_big_stripe_cached(struct r5conf *conf, sector_t sect);
#endif
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-06 18:43:14 +0000