177 lines
5.5 KiB
Diff
177 lines
5.5 KiB
Diff
From: Mike Galbraith <umgwanakikbuti@gmail.com>
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Date: Thu, 31 Mar 2016 04:08:28 +0200
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Subject: [PATCH] drivers/block/zram: Replace bit spinlocks with rtmutex
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for -rt
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Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.9/older/patches-4.9.30-rt20.tar.xz
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They're nondeterministic, and lead to ___might_sleep() splats in -rt.
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OTOH, they're a lot less wasteful than an rtmutex per page.
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Signed-off-by: Mike Galbraith <umgwanakikbuti@gmail.com>
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Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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---
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drivers/block/zram/zram_drv.c | 30 ++++++++++++++++--------------
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drivers/block/zram/zram_drv.h | 41 +++++++++++++++++++++++++++++++++++++++++
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2 files changed, 57 insertions(+), 14 deletions(-)
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--- a/drivers/block/zram/zram_drv.c
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+++ b/drivers/block/zram/zram_drv.c
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@@ -528,6 +528,8 @@ static struct zram_meta *zram_meta_alloc
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goto out_error;
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}
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+ zram_meta_init_table_locks(meta, disksize);
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+
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return meta;
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out_error:
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@@ -576,12 +578,12 @@ static int zram_decompress_page(struct z
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unsigned long handle;
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unsigned int size;
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- bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);
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+ zram_lock_table(&meta->table[index]);
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handle = meta->table[index].handle;
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size = zram_get_obj_size(meta, index);
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if (!handle || zram_test_flag(meta, index, ZRAM_ZERO)) {
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- bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
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+ zram_unlock_table(&meta->table[index]);
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memset(mem, 0, PAGE_SIZE);
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return 0;
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}
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@@ -596,7 +598,7 @@ static int zram_decompress_page(struct z
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zcomp_stream_put(zram->comp);
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}
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zs_unmap_object(meta->mem_pool, handle);
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- bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
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+ zram_unlock_table(&meta->table[index]);
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/* Should NEVER happen. Return bio error if it does. */
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if (unlikely(ret)) {
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@@ -616,14 +618,14 @@ static int zram_bvec_read(struct zram *z
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struct zram_meta *meta = zram->meta;
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page = bvec->bv_page;
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- bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);
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+ zram_lock_table(&meta->table[index]);
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if (unlikely(!meta->table[index].handle) ||
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zram_test_flag(meta, index, ZRAM_ZERO)) {
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- bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
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+ zram_unlock_table(&meta->table[index]);
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handle_zero_page(bvec);
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return 0;
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}
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- bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
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+ zram_unlock_table(&meta->table[index]);
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if (is_partial_io(bvec))
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/* Use a temporary buffer to decompress the page */
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@@ -700,10 +702,10 @@ static int zram_bvec_write(struct zram *
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if (user_mem)
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kunmap_atomic(user_mem);
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/* Free memory associated with this sector now. */
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- bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);
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+ zram_lock_table(&meta->table[index]);
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zram_free_page(zram, index);
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zram_set_flag(meta, index, ZRAM_ZERO);
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- bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
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+ zram_unlock_table(&meta->table[index]);
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atomic64_inc(&zram->stats.zero_pages);
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ret = 0;
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@@ -794,12 +796,12 @@ static int zram_bvec_write(struct zram *
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* Free memory associated with this sector
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* before overwriting unused sectors.
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*/
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- bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);
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+ zram_lock_table(&meta->table[index]);
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zram_free_page(zram, index);
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meta->table[index].handle = handle;
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zram_set_obj_size(meta, index, clen);
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- bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
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+ zram_unlock_table(&meta->table[index]);
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/* Update stats */
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atomic64_add(clen, &zram->stats.compr_data_size);
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@@ -842,9 +844,9 @@ static void zram_bio_discard(struct zram
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}
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while (n >= PAGE_SIZE) {
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- bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);
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+ zram_lock_table(&meta->table[index]);
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zram_free_page(zram, index);
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- bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
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+ zram_unlock_table(&meta->table[index]);
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atomic64_inc(&zram->stats.notify_free);
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index++;
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n -= PAGE_SIZE;
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@@ -973,9 +975,9 @@ static void zram_slot_free_notify(struct
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zram = bdev->bd_disk->private_data;
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meta = zram->meta;
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- bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);
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+ zram_lock_table(&meta->table[index]);
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zram_free_page(zram, index);
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- bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
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+ zram_unlock_table(&meta->table[index]);
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atomic64_inc(&zram->stats.notify_free);
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}
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--- a/drivers/block/zram/zram_drv.h
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+++ b/drivers/block/zram/zram_drv.h
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@@ -73,6 +73,9 @@ enum zram_pageflags {
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struct zram_table_entry {
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unsigned long handle;
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unsigned long value;
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+#ifdef CONFIG_PREEMPT_RT_BASE
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+ spinlock_t lock;
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+#endif
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};
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struct zram_stats {
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@@ -120,4 +123,42 @@ struct zram {
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*/
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bool claim; /* Protected by bdev->bd_mutex */
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};
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+
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+#ifndef CONFIG_PREEMPT_RT_BASE
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+static inline void zram_lock_table(struct zram_table_entry *table)
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+{
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+ bit_spin_lock(ZRAM_ACCESS, &table->value);
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+}
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+
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+static inline void zram_unlock_table(struct zram_table_entry *table)
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+{
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+ bit_spin_unlock(ZRAM_ACCESS, &table->value);
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+}
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+
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+static inline void zram_meta_init_table_locks(struct zram_meta *meta, u64 disksize) { }
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+#else /* CONFIG_PREEMPT_RT_BASE */
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+static inline void zram_lock_table(struct zram_table_entry *table)
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+{
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+ spin_lock(&table->lock);
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+ __set_bit(ZRAM_ACCESS, &table->value);
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+}
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+
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+static inline void zram_unlock_table(struct zram_table_entry *table)
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+{
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+ __clear_bit(ZRAM_ACCESS, &table->value);
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+ spin_unlock(&table->lock);
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+}
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+
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+static inline void zram_meta_init_table_locks(struct zram_meta *meta, u64 disksize)
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+{
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+ size_t num_pages = disksize >> PAGE_SHIFT;
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+ size_t index;
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+
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+ for (index = 0; index < num_pages; index++) {
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+ spinlock_t *lock = &meta->table[index].lock;
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+ spin_lock_init(lock);
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+ }
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+}
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+#endif /* CONFIG_PREEMPT_RT_BASE */
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+
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#endif
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