diff options
| -rw-r--r-- | drivers/staging/erofs/decompressor.c | 50 |
1 files changed, 28 insertions, 22 deletions
diff --git a/drivers/staging/erofs/decompressor.c b/drivers/staging/erofs/decompressor.c index 80f1f39719ba..1fb0abb98dff 100644 --- a/drivers/staging/erofs/decompressor.c +++ b/drivers/staging/erofs/decompressor.c @@ -13,7 +13,7 @@ #define LZ4_DISTANCE_MAX 65535 /* set to maximum value by default */ #endif -#define LZ4_MAX_DISTANCE_PAGES DIV_ROUND_UP(LZ4_DISTANCE_MAX, PAGE_SIZE) +#define LZ4_MAX_DISTANCE_PAGES (DIV_ROUND_UP(LZ4_DISTANCE_MAX, PAGE_SIZE) + 1) #ifndef LZ4_DECOMPRESS_INPLACE_MARGIN #define LZ4_DECOMPRESS_INPLACE_MARGIN(srcsize) (((srcsize) >> 8) + 32) #endif @@ -35,19 +35,28 @@ static int lz4_prepare_destpages(struct z_erofs_decompress_req *rq, const unsigned int nr = PAGE_ALIGN(rq->pageofs_out + rq->outputsize) >> PAGE_SHIFT; struct page *availables[LZ4_MAX_DISTANCE_PAGES] = { NULL }; - unsigned long unused[DIV_ROUND_UP(LZ4_MAX_DISTANCE_PAGES, - BITS_PER_LONG)] = { 0 }; + unsigned long bounced[DIV_ROUND_UP(LZ4_MAX_DISTANCE_PAGES, + BITS_PER_LONG)] = { 0 }; void *kaddr = NULL; - unsigned int i, j, k; + unsigned int i, j, top; - for (i = 0; i < nr; ++i) { + top = 0; + for (i = j = 0; i < nr; ++i, ++j) { struct page *const page = rq->out[i]; + struct page *victim; - j = i & (LZ4_MAX_DISTANCE_PAGES - 1); - if (availables[j]) - __set_bit(j, unused); + if (j >= LZ4_MAX_DISTANCE_PAGES) + j = 0; + + /* 'valid' bounced can only be tested after a complete round */ + if (test_bit(j, bounced)) { + DBG_BUGON(i < LZ4_MAX_DISTANCE_PAGES); + DBG_BUGON(top >= LZ4_MAX_DISTANCE_PAGES); + availables[top++] = rq->out[i - LZ4_MAX_DISTANCE_PAGES]; + } if (page) { + __clear_bit(j, bounced); if (kaddr) { if (kaddr + PAGE_SIZE == page_address(page)) kaddr += PAGE_SIZE; @@ -59,27 +68,24 @@ static int lz4_prepare_destpages(struct z_erofs_decompress_req *rq, continue; } kaddr = NULL; + __set_bit(j, bounced); - k = find_first_bit(unused, LZ4_MAX_DISTANCE_PAGES); - if (k < LZ4_MAX_DISTANCE_PAGES) { - j = k; - get_page(availables[j]); + if (top) { + victim = availables[--top]; + get_page(victim); } else { - DBG_BUGON(availables[j]); - if (!list_empty(pagepool)) { - availables[j] = lru_to_page(pagepool); - list_del(&availables[j]->lru); - DBG_BUGON(page_ref_count(availables[j]) != 1); + victim = lru_to_page(pagepool); + list_del(&victim->lru); + DBG_BUGON(page_ref_count(victim) != 1); } else { - availables[j] = alloc_pages(GFP_KERNEL, 0); - if (!availables[j]) + victim = alloc_pages(GFP_KERNEL, 0); + if (!victim) return -ENOMEM; } - availables[j]->mapping = Z_EROFS_MAPPING_STAGING; + victim->mapping = Z_EROFS_MAPPING_STAGING; } - rq->out[i] = availables[j]; - __clear_bit(j, unused); + rq->out[i] = victim; } return kaddr ? 1 : 0; } |