In dm-pcache, in order to ensure crash-consistency, a dual-copy scheme is used to alternately update metadata, and there is a slot index that records the current slot. However, in the write path the current implementation writes directly to the current slot indexed by slot index, and then advances the slot — which ends up overwriting the existing slot, violating the crash-consistency guarantee.
This patch fixes that behavior, preventing metadata from being overwritten incorrectly.
In addition, this patch add a missing pmem_wmb() after memcpy_flushcache().
Signed-off-by: Dongsheng Yang dongsheng.yang@linux.dev Reviewed-by: Zheng Gu cengku@gmail.com Cc: stable@vger.kernel.org # 6.18 --- drivers/md/dm-pcache/cache.c | 8 ++++---- drivers/md/dm-pcache/cache_segment.c | 8 ++++---- 2 files changed, 8 insertions(+), 8 deletions(-)
diff --git a/drivers/md/dm-pcache/cache.c b/drivers/md/dm-pcache/cache.c index 698697a7a73c..d4385d76ac36 100644 --- a/drivers/md/dm-pcache/cache.c +++ b/drivers/md/dm-pcache/cache.c @@ -21,10 +21,10 @@ static void cache_info_write(struct pcache_cache *cache) cache_info->header.crc = pcache_meta_crc(&cache_info->header, sizeof(struct pcache_cache_info));
+ cache->info_index = (cache->info_index + 1) % PCACHE_META_INDEX_MAX; memcpy_flushcache(get_cache_info_addr(cache), cache_info, sizeof(struct pcache_cache_info)); - - cache->info_index = (cache->info_index + 1) % PCACHE_META_INDEX_MAX; + pmem_wmb(); }
static void cache_info_init_default(struct pcache_cache *cache); @@ -93,10 +93,10 @@ void cache_pos_encode(struct pcache_cache *cache, pos_onmedia.header.seq = seq; pos_onmedia.header.crc = cache_pos_onmedia_crc(&pos_onmedia);
+ *index = (*index + 1) % PCACHE_META_INDEX_MAX; + memcpy_flushcache(pos_onmedia_addr, &pos_onmedia, sizeof(struct pcache_cache_pos_onmedia)); pmem_wmb(); - - *index = (*index + 1) % PCACHE_META_INDEX_MAX; }
int cache_pos_decode(struct pcache_cache *cache, diff --git a/drivers/md/dm-pcache/cache_segment.c b/drivers/md/dm-pcache/cache_segment.c index f0b58980806e..ae57cc261422 100644 --- a/drivers/md/dm-pcache/cache_segment.c +++ b/drivers/md/dm-pcache/cache_segment.c @@ -26,11 +26,11 @@ static void cache_seg_info_write(struct pcache_cache_segment *cache_seg) seg_info->header.seq++; seg_info->header.crc = pcache_meta_crc(&seg_info->header, sizeof(struct pcache_segment_info));
+ cache_seg->info_index = (cache_seg->info_index + 1) % PCACHE_META_INDEX_MAX; + seg_info_addr = get_seg_info_addr(cache_seg); memcpy_flushcache(seg_info_addr, seg_info, sizeof(struct pcache_segment_info)); pmem_wmb(); - - cache_seg->info_index = (cache_seg->info_index + 1) % PCACHE_META_INDEX_MAX; mutex_unlock(&cache_seg->info_lock); }
@@ -129,10 +129,10 @@ static void cache_seg_ctrl_write(struct pcache_cache_segment *cache_seg) cache_seg_gen.header.crc = pcache_meta_crc(&cache_seg_gen.header, sizeof(struct pcache_cache_seg_gen));
+ cache_seg->gen_index = (cache_seg->gen_index + 1) % PCACHE_META_INDEX_MAX; + memcpy_flushcache(get_cache_seg_gen_addr(cache_seg), &cache_seg_gen, sizeof(struct pcache_cache_seg_gen)); pmem_wmb(); - - cache_seg->gen_index = (cache_seg->gen_index + 1) % PCACHE_META_INDEX_MAX; }
static void cache_seg_ctrl_init(struct pcache_cache_segment *cache_seg)
From: Li Chen chenl311@chinatelecom.cn
The on-media cache_info index used sizeof(struct) instead of the 4K metadata stride, so gc_percent updates from dmsetup message were written between slots and lost after reboot. Use PCACHE_CACHE_INFO_SIZE in get_cache_info_addr() and align info_index with the slot returned by pcache_meta_find_latest().
Signed-off-by: Li Chen chenl311@chinatelecom.cn Signed-off-by: Dongsheng Yang dongsheng.yang@linux.dev Reviewed-by: Zheng Gu cengku@gmail.com Cc: stable@vger.kernel.org # 6.18 --- drivers/md/dm-pcache/cache.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/drivers/md/dm-pcache/cache.c b/drivers/md/dm-pcache/cache.c index d4385d76ac36..534bf07b794f 100644 --- a/drivers/md/dm-pcache/cache.c +++ b/drivers/md/dm-pcache/cache.c @@ -10,7 +10,8 @@ struct kmem_cache *key_cache;
static inline struct pcache_cache_info *get_cache_info_addr(struct pcache_cache *cache) { - return cache->cache_info_addr + cache->info_index; + return (struct pcache_cache_info *)((char *)cache->cache_info_addr + + (size_t)cache->info_index * PCACHE_CACHE_INFO_SIZE); }
static void cache_info_write(struct pcache_cache *cache) @@ -49,6 +50,8 @@ static int cache_info_init(struct pcache_cache *cache, struct pcache_cache_optio return -EINVAL; }
+ cache->info_index = ((char *)cache_info_addr - (char *)cache->cache_info_addr) / PCACHE_CACHE_INFO_SIZE; + return 0; }
From: Li Chen chenl311@chinatelecom.cn
Segment info indexing also used sizeof(struct) instead of the 4K metadata stride, so info_index could point between slots and subsequent writes would advance incorrectly. Derive info_index from the pointer returned by the segment meta search using PCACHE_SEG_INFO_SIZE and advance to the next slot for future updates.
Signed-off-by: Li Chen chenl311@chinatelecom.cn Signed-off-by: Dongsheng Yang dongsheng.yang@linux.dev Reviewed-by: Zheng Gu cengku@gmail.com Cc: stable@vger.kernel.org # 6.18 --- drivers/md/dm-pcache/cache_segment.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/drivers/md/dm-pcache/cache_segment.c b/drivers/md/dm-pcache/cache_segment.c index ae57cc261422..9d92e2b067ed 100644 --- a/drivers/md/dm-pcache/cache_segment.c +++ b/drivers/md/dm-pcache/cache_segment.c @@ -56,7 +56,10 @@ static int cache_seg_info_load(struct pcache_cache_segment *cache_seg) ret = -EIO; goto out; } - cache_seg->info_index = cache_seg_info_addr - cache_seg_info_addr_base; + + cache_seg->info_index = + ((char *)cache_seg_info_addr - (char *)cache_seg_info_addr_base) / + PCACHE_SEG_INFO_SIZE; out: mutex_unlock(&cache_seg->info_lock);
linux-stable-mirror@lists.linaro.org
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Dongsheng Yang