From 1825c8d7ce93c4725cb04ad09627fc2829de32ca Mon Sep 17 00:00:00 2001 From: Gao Xiang Date: Wed, 9 Dec 2020 20:37:17 +0800 Subject: erofs: force inplace I/O under low memory scenario Try to forcely switch to inplace I/O under low memory scenario in order to avoid direct memory reclaim due to cached page allocation. Link: https://lore.kernel.org/r/20201209123717.12430-1-hsiangkao@aol.com Reviewed-by: Chao Yu Signed-off-by: Gao Xiang --- fs/erofs/compress.h | 3 +++ fs/erofs/zdata.c | 48 ++++++++++++++++++++++++++++++++++++++++-------- 2 files changed, 43 insertions(+), 8 deletions(-) (limited to 'fs') diff --git a/fs/erofs/compress.h b/fs/erofs/compress.h index 4dadde18cdf1..aea129ddda74 100644 --- a/fs/erofs/compress.h +++ b/fs/erofs/compress.h @@ -28,11 +28,13 @@ struct z_erofs_decompress_req { /* some special page->private (unsigned long, see below) */ #define Z_EROFS_SHORTLIVED_PAGE (-1UL << 2) +#define Z_EROFS_PREALLOCATED_PAGE (-2UL << 2) /* * For all pages in a pcluster, page->private should be one of * Type Last 2bits page->private * short-lived page 00 Z_EROFS_SHORTLIVED_PAGE + * preallocated page (tryalloc) 00 Z_EROFS_PREALLOCATED_PAGE * cached/managed page 00 pointer to z_erofs_pcluster * online page (file-backed, 01/10/11 sub-index << 2 | count * some pages can be used for inplace I/O) @@ -40,6 +42,7 @@ struct z_erofs_decompress_req { * page->mapping should be one of * Type page->mapping * short-lived page NULL + * preallocated page NULL * cached/managed page non-NULL or NULL (invalidated/truncated page) * online page non-NULL * diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c index 777790038bc9..6cb356c4217b 100644 --- a/fs/erofs/zdata.c +++ b/fs/erofs/zdata.c @@ -20,6 +20,11 @@ enum z_erofs_cache_alloctype { DONTALLOC, /* don't allocate any cached pages */ DELAYEDALLOC, /* delayed allocation (at the time of submitting io) */ + /* + * try to use cached I/O if page allocation succeeds or fallback + * to in-place I/O instead to avoid any direct reclaim. + */ + TRYALLOC, }; /* @@ -154,13 +159,16 @@ static DEFINE_MUTEX(z_pagemap_global_lock); static void preload_compressed_pages(struct z_erofs_collector *clt, struct address_space *mc, - enum z_erofs_cache_alloctype type) + enum z_erofs_cache_alloctype type, + struct list_head *pagepool) { const struct z_erofs_pcluster *pcl = clt->pcl; const unsigned int clusterpages = BIT(pcl->clusterbits); struct page **pages = clt->compressedpages; pgoff_t index = pcl->obj.index + (pages - pcl->compressed_pages); bool standalone = true; + gfp_t gfp = (mapping_gfp_mask(mc) & ~__GFP_DIRECT_RECLAIM) | + __GFP_NOMEMALLOC | __GFP_NORETRY | __GFP_NOWARN; if (clt->mode < COLLECT_PRIMARY_FOLLOWED) return; @@ -168,6 +176,7 @@ static void preload_compressed_pages(struct z_erofs_collector *clt, for (; pages < pcl->compressed_pages + clusterpages; ++pages) { struct page *page; compressed_page_t t; + struct page *newpage = NULL; /* the compressed page was loaded before */ if (READ_ONCE(*pages)) @@ -179,7 +188,15 @@ static void preload_compressed_pages(struct z_erofs_collector *clt, t = tag_compressed_page_justfound(page); } else if (type == DELAYEDALLOC) { t = tagptr_init(compressed_page_t, PAGE_UNALLOCATED); + } else if (type == TRYALLOC) { + newpage = erofs_allocpage(pagepool, gfp); + if (!newpage) + goto dontalloc; + + set_page_private(newpage, Z_EROFS_PREALLOCATED_PAGE); + t = tag_compressed_page_justfound(newpage); } else { /* DONTALLOC */ +dontalloc: if (standalone) clt->compressedpages = pages; standalone = false; @@ -189,8 +206,12 @@ static void preload_compressed_pages(struct z_erofs_collector *clt, if (!cmpxchg_relaxed(pages, NULL, tagptr_cast_ptr(t))) continue; - if (page) + if (page) { put_page(page); + } else if (newpage) { + set_page_private(newpage, 0); + list_add(&newpage->lru, pagepool); + } } if (standalone) /* downgrade to PRIMARY_FOLLOWED_NOINPLACE */ @@ -554,7 +575,7 @@ static bool should_alloc_managed_pages(struct z_erofs_decompress_frontend *fe, } static int z_erofs_do_read_page(struct z_erofs_decompress_frontend *fe, - struct page *page) + struct page *page, struct list_head *pagepool) { struct inode *const inode = fe->inode; struct erofs_sb_info *const sbi = EROFS_I_SB(inode); @@ -607,11 +628,12 @@ restart_now: /* preload all compressed pages (maybe downgrade role if necessary) */ if (should_alloc_managed_pages(fe, sbi->ctx.cache_strategy, map->m_la)) - cache_strategy = DELAYEDALLOC; + cache_strategy = TRYALLOC; else cache_strategy = DONTALLOC; - preload_compressed_pages(clt, MNGD_MAPPING(sbi), cache_strategy); + preload_compressed_pages(clt, MNGD_MAPPING(sbi), + cache_strategy, pagepool); hitted: /* @@ -1005,6 +1027,16 @@ repeat: justfound = tagptr_unfold_tags(t); page = tagptr_unfold_ptr(t); + /* + * preallocated cached pages, which is used to avoid direct reclaim + * otherwise, it will go inplace I/O path instead. + */ + if (page->private == Z_EROFS_PREALLOCATED_PAGE) { + WRITE_ONCE(pcl->compressed_pages[nr], page); + set_page_private(page, 0); + tocache = true; + goto out_tocache; + } mapping = READ_ONCE(page->mapping); /* @@ -1067,7 +1099,7 @@ out_allocpage: cond_resched(); goto repeat; } - +out_tocache: if (!tocache || add_to_page_cache_lru(page, mc, index + nr, gfp)) { /* turn into temporary page if fails (1 ref) */ set_page_private(page, Z_EROFS_SHORTLIVED_PAGE); @@ -1278,7 +1310,7 @@ static int z_erofs_readpage(struct file *file, struct page *page) f.headoffset = (erofs_off_t)page->index << PAGE_SHIFT; - err = z_erofs_do_read_page(&f, page); + err = z_erofs_do_read_page(&f, page, &pagepool); (void)z_erofs_collector_end(&f.clt); /* if some compressed cluster ready, need submit them anyway */ @@ -1332,7 +1364,7 @@ static void z_erofs_readahead(struct readahead_control *rac) /* traversal in reverse order */ head = (void *)page_private(page); - err = z_erofs_do_read_page(&f, page); + err = z_erofs_do_read_page(&f, page, &pagepool); if (err) erofs_err(inode->i_sb, "readahead error at page %lu @ nid %llu", -- cgit v1.2.3-59-g8ed1b