diff options
| author | Dongsheng Yang <dongsheng.yang@linux.dev> | 2025-12-05 05:46:18 +0000 |
|---|---|---|
| committer | Mikulas Patocka <mpatocka@redhat.com> | 2025-12-10 19:28:23 +0100 |
| commit | ebbb90344a7da2421e4b54668b94e81828b8b308 (patch) | |
| tree | 0e416898b4c80f4a69eb40432d41042ed30223b1 | |
| parent | 7799eaecfeb756664be37c079520af67d5d64f70 (diff) | |
dm-pcache: advance slot index before writing slot
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>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Reviewed-by: Zheng Gu <cengku@gmail.com>
Cc: stable@vger.kernel.org # 6.18
| -rw-r--r-- | drivers/md/dm-pcache/cache.c | 8 | ||||
| -rw-r--r-- | 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 d8e92367d947..d93aeb67c492 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) |