From 97cf5d53b4812dcb52c13fda700dad5aa8d3446c Mon Sep 17 00:00:00 2001 From: Jingbo Xu Date: Wed, 24 Jan 2024 11:19:45 +0800 Subject: [PATCH 1/3] erofs: get rid of unneeded GFP_NOFS Clean up some leftovers since there is no way for EROFS to be called again from a reclaim context. Signed-off-by: Jingbo Xu Reviewed-by: Gao Xiang Link: https://lore.kernel.org/r/20240124031945.130782-1-jefflexu@linux.alibaba.com Signed-off-by: Gao Xiang --- fs/erofs/fscache.c | 2 +- fs/erofs/inode.c | 2 +- fs/erofs/utils.c | 2 +- fs/erofs/zdata.c | 8 ++++---- 4 files changed, 7 insertions(+), 7 deletions(-) diff --git a/fs/erofs/fscache.c b/fs/erofs/fscache.c index bc12030393b2..5ff90026fd43 100644 --- a/fs/erofs/fscache.c +++ b/fs/erofs/fscache.c @@ -459,7 +459,7 @@ static struct erofs_fscache *erofs_fscache_acquire_cookie(struct super_block *sb inode->i_size = OFFSET_MAX; inode->i_mapping->a_ops = &erofs_fscache_meta_aops; - mapping_set_gfp_mask(inode->i_mapping, GFP_NOFS); + mapping_set_gfp_mask(inode->i_mapping, GFP_KERNEL); inode->i_blkbits = EROFS_SB(sb)->blkszbits; inode->i_private = ctx; diff --git a/fs/erofs/inode.c b/fs/erofs/inode.c index 3d616dea55dc..36e638e8b53a 100644 --- a/fs/erofs/inode.c +++ b/fs/erofs/inode.c @@ -60,7 +60,7 @@ static void *erofs_read_inode(struct erofs_buf *buf, } else { const unsigned int gotten = sb->s_blocksize - *ofs; - copied = kmalloc(vi->inode_isize, GFP_NOFS); + copied = kmalloc(vi->inode_isize, GFP_KERNEL); if (!copied) { err = -ENOMEM; goto err_out; diff --git a/fs/erofs/utils.c b/fs/erofs/utils.c index 5dea308764b4..e146d09151af 100644 --- a/fs/erofs/utils.c +++ b/fs/erofs/utils.c @@ -81,7 +81,7 @@ struct erofs_workgroup *erofs_insert_workgroup(struct super_block *sb, repeat: xa_lock(&sbi->managed_pslots); pre = __xa_cmpxchg(&sbi->managed_pslots, grp->index, - NULL, grp, GFP_NOFS); + NULL, grp, GFP_KERNEL); if (pre) { if (xa_is_err(pre)) { pre = ERR_PTR(xa_err(pre)); diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c index 692c0c39be63..583c062cd0e4 100644 --- a/fs/erofs/zdata.c +++ b/fs/erofs/zdata.c @@ -230,7 +230,7 @@ static int z_erofs_bvec_enqueue(struct z_erofs_bvec_iter *iter, struct page *nextpage = *candidate_bvpage; if (!nextpage) { - nextpage = erofs_allocpage(pagepool, GFP_NOFS); + nextpage = erofs_allocpage(pagepool, GFP_KERNEL); if (!nextpage) return -ENOMEM; set_page_private(nextpage, Z_EROFS_SHORTLIVED_PAGE); @@ -302,7 +302,7 @@ static struct z_erofs_pcluster *z_erofs_alloc_pcluster(unsigned int size) if (nrpages > pcs->maxpages) continue; - pcl = kmem_cache_zalloc(pcs->slab, GFP_NOFS); + pcl = kmem_cache_zalloc(pcs->slab, GFP_KERNEL); if (!pcl) return ERR_PTR(-ENOMEM); pcl->pclustersize = size; @@ -694,7 +694,7 @@ static void z_erofs_cache_invalidate_folio(struct folio *folio, DBG_BUGON(stop > folio_size(folio) || stop < length); if (offset == 0 && stop == folio_size(folio)) - while (!z_erofs_cache_release_folio(folio, GFP_NOFS)) + while (!z_erofs_cache_release_folio(folio, 0)) cond_resched(); } @@ -713,7 +713,7 @@ int erofs_init_managed_cache(struct super_block *sb) set_nlink(inode, 1); inode->i_size = OFFSET_MAX; inode->i_mapping->a_ops = &z_erofs_cache_aops; - mapping_set_gfp_mask(inode->i_mapping, GFP_NOFS); + mapping_set_gfp_mask(inode->i_mapping, GFP_KERNEL); EROFS_SB(sb)->managed_cache = inode; return 0; } From cc4b2dd95f0d1eba8c691b36e8f4d1795582f1ff Mon Sep 17 00:00:00 2001 From: Gao Xiang Date: Thu, 25 Jan 2024 20:00:39 +0800 Subject: [PATCH 2/3] erofs: fix infinite loop due to a race of filling compressed_bvecs I encountered a race issue after lengthy (~594647 secs) stress tests on a 64k-page arm64 VM with several 4k-block EROFS images. The timing is like below: z_erofs_try_inplace_io z_erofs_fill_bio_vec cmpxchg(&compressed_bvecs[].page, NULL, ..) [access bufvec] compressed_bvecs[] = *bvec; Previously, z_erofs_submit_queue() just accessed bufvec->page only, so other fields in bufvec didn't matter. After the subpage block support is landed, .offset and .end can be used too, but filling bufvec isn't an atomic operation which can cause inconsistency. Let's use a spinlock to keep the atomicity of each bufvec. More specifically, just reuse the existing spinlock `pcl->obj.lockref.lock` since it's rarely used (also it takes a short time if even used) as long as the pcluster has a reference. Fixes: 192351616a9d ("erofs: support I/O submission for sub-page compressed blocks") Signed-off-by: Gao Xiang Reviewed-by: Yue Hu Reviewed-by: Sandeep Dhavale Link: https://lore.kernel.org/r/20240125120039.3228103-1-hsiangkao@linux.alibaba.com --- fs/erofs/zdata.c | 74 +++++++++++++++++++++++++----------------------- 1 file changed, 38 insertions(+), 36 deletions(-) diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c index 583c062cd0e4..c1c77166b30f 100644 --- a/fs/erofs/zdata.c +++ b/fs/erofs/zdata.c @@ -563,21 +563,19 @@ static void z_erofs_bind_cache(struct z_erofs_decompress_frontend *fe) __GFP_NOMEMALLOC | __GFP_NORETRY | __GFP_NOWARN; unsigned int i; - if (i_blocksize(fe->inode) != PAGE_SIZE) - return; - if (fe->mode < Z_EROFS_PCLUSTER_FOLLOWED) + if (i_blocksize(fe->inode) != PAGE_SIZE || + fe->mode < Z_EROFS_PCLUSTER_FOLLOWED) return; for (i = 0; i < pclusterpages; ++i) { struct page *page, *newpage; void *t; /* mark pages just found for debugging */ - /* the compressed page was loaded before */ + /* Inaccurate check w/o locking to avoid unneeded lookups */ if (READ_ONCE(pcl->compressed_bvecs[i].page)) continue; page = find_get_page(mc, pcl->obj.index + i); - if (page) { t = (void *)((unsigned long)page | 1); newpage = NULL; @@ -597,9 +595,13 @@ static void z_erofs_bind_cache(struct z_erofs_decompress_frontend *fe) set_page_private(newpage, Z_EROFS_PREALLOCATED_PAGE); t = (void *)((unsigned long)newpage | 1); } - - if (!cmpxchg_relaxed(&pcl->compressed_bvecs[i].page, NULL, t)) + spin_lock(&pcl->obj.lockref.lock); + if (!pcl->compressed_bvecs[i].page) { + pcl->compressed_bvecs[i].page = t; + spin_unlock(&pcl->obj.lockref.lock); continue; + } + spin_unlock(&pcl->obj.lockref.lock); if (page) put_page(page); @@ -718,31 +720,25 @@ int erofs_init_managed_cache(struct super_block *sb) return 0; } -static bool z_erofs_try_inplace_io(struct z_erofs_decompress_frontend *fe, - struct z_erofs_bvec *bvec) -{ - struct z_erofs_pcluster *const pcl = fe->pcl; - - while (fe->icur > 0) { - if (!cmpxchg(&pcl->compressed_bvecs[--fe->icur].page, - NULL, bvec->page)) { - pcl->compressed_bvecs[fe->icur] = *bvec; - return true; - } - } - return false; -} - /* callers must be with pcluster lock held */ static int z_erofs_attach_page(struct z_erofs_decompress_frontend *fe, struct z_erofs_bvec *bvec, bool exclusive) { + struct z_erofs_pcluster *pcl = fe->pcl; int ret; if (exclusive) { /* give priority for inplaceio to use file pages first */ - if (z_erofs_try_inplace_io(fe, bvec)) + spin_lock(&pcl->obj.lockref.lock); + while (fe->icur > 0) { + if (pcl->compressed_bvecs[--fe->icur].page) + continue; + pcl->compressed_bvecs[fe->icur] = *bvec; + spin_unlock(&pcl->obj.lockref.lock); return 0; + } + spin_unlock(&pcl->obj.lockref.lock); + /* otherwise, check if it can be used as a bvpage */ if (fe->mode >= Z_EROFS_PCLUSTER_FOLLOWED && !fe->candidate_bvpage) @@ -1423,23 +1419,26 @@ static void z_erofs_fill_bio_vec(struct bio_vec *bvec, { gfp_t gfp = mapping_gfp_mask(mc); bool tocache = false; - struct z_erofs_bvec *zbv = pcl->compressed_bvecs + nr; + struct z_erofs_bvec zbv; struct address_space *mapping; - struct page *page, *oldpage; + struct page *page; int justfound, bs = i_blocksize(f->inode); /* Except for inplace pages, the entire page can be used for I/Os */ bvec->bv_offset = 0; bvec->bv_len = PAGE_SIZE; repeat: - oldpage = READ_ONCE(zbv->page); - if (!oldpage) + spin_lock(&pcl->obj.lockref.lock); + zbv = pcl->compressed_bvecs[nr]; + page = zbv.page; + justfound = (unsigned long)page & 1UL; + page = (struct page *)((unsigned long)page & ~1UL); + pcl->compressed_bvecs[nr].page = page; + spin_unlock(&pcl->obj.lockref.lock); + if (!page) goto out_allocpage; - justfound = (unsigned long)oldpage & 1UL; - page = (struct page *)((unsigned long)oldpage & ~1UL); bvec->bv_page = page; - DBG_BUGON(z_erofs_is_shortlived_page(page)); /* * Handle preallocated cached pages. We tried to allocate such pages @@ -1448,7 +1447,6 @@ static void z_erofs_fill_bio_vec(struct bio_vec *bvec, */ if (page->private == Z_EROFS_PREALLOCATED_PAGE) { set_page_private(page, 0); - WRITE_ONCE(zbv->page, page); tocache = true; goto out_tocache; } @@ -1459,9 +1457,9 @@ static void z_erofs_fill_bio_vec(struct bio_vec *bvec, * therefore it is impossible for `mapping` to be NULL. */ if (mapping && mapping != mc) { - if (zbv->offset < 0) - bvec->bv_offset = round_up(-zbv->offset, bs); - bvec->bv_len = round_up(zbv->end, bs) - bvec->bv_offset; + if (zbv.offset < 0) + bvec->bv_offset = round_up(-zbv.offset, bs); + bvec->bv_len = round_up(zbv.end, bs) - bvec->bv_offset; return; } @@ -1471,7 +1469,6 @@ static void z_erofs_fill_bio_vec(struct bio_vec *bvec, /* the cached page is still in managed cache */ if (page->mapping == mc) { - WRITE_ONCE(zbv->page, page); /* * The cached page is still available but without a valid * `->private` pcluster hint. Let's reconnect them. @@ -1503,11 +1500,15 @@ static void z_erofs_fill_bio_vec(struct bio_vec *bvec, put_page(page); out_allocpage: page = erofs_allocpage(&f->pagepool, gfp | __GFP_NOFAIL); - if (oldpage != cmpxchg(&zbv->page, oldpage, page)) { + spin_lock(&pcl->obj.lockref.lock); + if (pcl->compressed_bvecs[nr].page) { erofs_pagepool_add(&f->pagepool, page); + spin_unlock(&pcl->obj.lockref.lock); cond_resched(); goto repeat; } + pcl->compressed_bvecs[nr].page = page; + spin_unlock(&pcl->obj.lockref.lock); bvec->bv_page = page; out_tocache: if (!tocache || bs != PAGE_SIZE || @@ -1685,6 +1686,7 @@ static void z_erofs_submit_queue(struct z_erofs_decompress_frontend *f, if (cur + bvec.bv_len > end) bvec.bv_len = end - cur; + DBG_BUGON(bvec.bv_len < sb->s_blocksize); if (!bio_add_page(bio, bvec.bv_page, bvec.bv_len, bvec.bv_offset)) goto submit_bio_retry; From d9281660ff3ffb4a05302b485cc59a87e709aefc Mon Sep 17 00:00:00 2001 From: Chunhai Guo Date: Fri, 26 Jan 2024 22:01:42 +0800 Subject: [PATCH 3/3] erofs: relaxed temporary buffers allocation on readahead Even with inplace decompression, sometimes very few temporary buffers may be still needed for a single decompression shot (e.g. 16 pages for 64k sliding window or 4 pages for 16k sliding window). In low-memory scenarios, it would be better to try to allocate with GFP_NOWAIT on readahead first. That can help reduce the time spent on page allocation under durative memory pressure. Here are detailed performance numbers under multi-app launch benchmark workload [1] on ARM64 Android devices (8-core CPU and 8GB of memory) running a 5.15 LTS kernel with EROFS of 4k pclusters: +----------------------------------------------+ | LZ4 | vanilla | patched | diff | |----------------+---------+---------+---------| | Average (ms) | 3364 | 2684 | -20.21% | [64k sliding window] |----------------+---------+---------+---------| | Average (ms) | 2079 | 1610 | -22.56% | [16k sliding window] +----------------------------------------------+ The total size of system images for 4k pclusters is almost unchanged: (64k sliding window) 9,117,044 KB (16k sliding window) 9,113,096 KB Therefore, in addition to switch the sliding window from 64k to 16k, after applying this patch, it can eventually save 52.14% (3364 -> 1610) on average with no memory reservation. That is particularly useful for embedded devices with limited resources. [1] https://lore.kernel.org/r/20240109074143.4138783-1-guochunhai@vivo.com Suggested-by: Gao Xiang Signed-off-by: Chunhai Guo Signed-off-by: Gao Xiang Reviewed-by: Yue Hu Link: https://lore.kernel.org/r/20240126140142.201718-1-hsiangkao@linux.alibaba.com --- fs/erofs/compress.h | 5 ++--- fs/erofs/decompressor.c | 5 +++-- fs/erofs/decompressor_deflate.c | 19 +++++++++++++------ fs/erofs/decompressor_lzma.c | 17 ++++++++++++----- fs/erofs/zdata.c | 16 ++++++++++++---- 5 files changed, 42 insertions(+), 20 deletions(-) diff --git a/fs/erofs/compress.h b/fs/erofs/compress.h index 279933e007d2..7cc5841577b2 100644 --- a/fs/erofs/compress.h +++ b/fs/erofs/compress.h @@ -11,13 +11,12 @@ struct z_erofs_decompress_req { struct super_block *sb; struct page **in, **out; - unsigned short pageofs_in, pageofs_out; unsigned int inputsize, outputsize; - /* indicate the algorithm will be used for decompression */ - unsigned int alg; + unsigned int alg; /* the algorithm for decompression */ bool inplace_io, partial_decoding, fillgaps; + gfp_t gfp; /* allocation flags for extra temporary buffers */ }; struct z_erofs_decompressor { diff --git a/fs/erofs/decompressor.c b/fs/erofs/decompressor.c index 072ef6a66823..d4cee95af14c 100644 --- a/fs/erofs/decompressor.c +++ b/fs/erofs/decompressor.c @@ -111,8 +111,9 @@ static int z_erofs_lz4_prepare_dstpages(struct z_erofs_lz4_decompress_ctx *ctx, victim = availables[--top]; get_page(victim); } else { - victim = erofs_allocpage(pagepool, - GFP_KERNEL | __GFP_NOFAIL); + victim = erofs_allocpage(pagepool, rq->gfp); + if (!victim) + return -ENOMEM; set_page_private(victim, Z_EROFS_SHORTLIVED_PAGE); } rq->out[i] = victim; diff --git a/fs/erofs/decompressor_deflate.c b/fs/erofs/decompressor_deflate.c index 4a64a9c91dd3..b98872058abe 100644 --- a/fs/erofs/decompressor_deflate.c +++ b/fs/erofs/decompressor_deflate.c @@ -95,7 +95,7 @@ int z_erofs_load_deflate_config(struct super_block *sb, } int z_erofs_deflate_decompress(struct z_erofs_decompress_req *rq, - struct page **pagepool) + struct page **pgpl) { const unsigned int nrpages_out = PAGE_ALIGN(rq->pageofs_out + rq->outputsize) >> PAGE_SHIFT; @@ -158,8 +158,12 @@ int z_erofs_deflate_decompress(struct z_erofs_decompress_req *rq, strm->z.avail_out = min_t(u32, outsz, PAGE_SIZE - pofs); outsz -= strm->z.avail_out; if (!rq->out[no]) { - rq->out[no] = erofs_allocpage(pagepool, - GFP_KERNEL | __GFP_NOFAIL); + rq->out[no] = erofs_allocpage(pgpl, rq->gfp); + if (!rq->out[no]) { + kout = NULL; + err = -ENOMEM; + break; + } set_page_private(rq->out[no], Z_EROFS_SHORTLIVED_PAGE); } @@ -211,8 +215,11 @@ int z_erofs_deflate_decompress(struct z_erofs_decompress_req *rq, DBG_BUGON(erofs_page_is_managed(EROFS_SB(sb), rq->in[j])); - tmppage = erofs_allocpage(pagepool, - GFP_KERNEL | __GFP_NOFAIL); + tmppage = erofs_allocpage(pgpl, rq->gfp); + if (!tmppage) { + err = -ENOMEM; + goto failed; + } set_page_private(tmppage, Z_EROFS_SHORTLIVED_PAGE); copy_highpage(tmppage, rq->in[j]); rq->in[j] = tmppage; @@ -230,7 +237,7 @@ int z_erofs_deflate_decompress(struct z_erofs_decompress_req *rq, break; } } - +failed: if (zlib_inflateEnd(&strm->z) != Z_OK && !err) err = -EIO; if (kout) diff --git a/fs/erofs/decompressor_lzma.c b/fs/erofs/decompressor_lzma.c index 2dd14f99c1dc..6ca357d83cfa 100644 --- a/fs/erofs/decompressor_lzma.c +++ b/fs/erofs/decompressor_lzma.c @@ -148,7 +148,7 @@ int z_erofs_load_lzma_config(struct super_block *sb, } int z_erofs_lzma_decompress(struct z_erofs_decompress_req *rq, - struct page **pagepool) + struct page **pgpl) { const unsigned int nrpages_out = PAGE_ALIGN(rq->pageofs_out + rq->outputsize) >> PAGE_SHIFT; @@ -215,8 +215,11 @@ int z_erofs_lzma_decompress(struct z_erofs_decompress_req *rq, PAGE_SIZE - pageofs); outlen -= strm->buf.out_size; if (!rq->out[no] && rq->fillgaps) { /* deduped */ - rq->out[no] = erofs_allocpage(pagepool, - GFP_KERNEL | __GFP_NOFAIL); + rq->out[no] = erofs_allocpage(pgpl, rq->gfp); + if (!rq->out[no]) { + err = -ENOMEM; + break; + } set_page_private(rq->out[no], Z_EROFS_SHORTLIVED_PAGE); } @@ -258,8 +261,11 @@ int z_erofs_lzma_decompress(struct z_erofs_decompress_req *rq, DBG_BUGON(erofs_page_is_managed(EROFS_SB(rq->sb), rq->in[j])); - tmppage = erofs_allocpage(pagepool, - GFP_KERNEL | __GFP_NOFAIL); + tmppage = erofs_allocpage(pgpl, rq->gfp); + if (!tmppage) { + err = -ENOMEM; + goto failed; + } set_page_private(tmppage, Z_EROFS_SHORTLIVED_PAGE); copy_highpage(tmppage, rq->in[j]); rq->in[j] = tmppage; @@ -277,6 +283,7 @@ int z_erofs_lzma_decompress(struct z_erofs_decompress_req *rq, break; } } +failed: if (no < nrpages_out && strm->buf.out) kunmap(rq->out[no]); if (ni < nrpages_in) diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c index c1c77166b30f..ff0aa72b0db3 100644 --- a/fs/erofs/zdata.c +++ b/fs/erofs/zdata.c @@ -82,6 +82,9 @@ struct z_erofs_pcluster { /* L: indicate several pageofs_outs or not */ bool multibases; + /* L: whether extra buffer allocations are best-effort */ + bool besteffort; + /* A: compressed bvecs (can be cached or inplaced pages) */ struct z_erofs_bvec compressed_bvecs[]; }; @@ -960,7 +963,7 @@ static int z_erofs_read_fragment(struct super_block *sb, struct page *page, } static int z_erofs_do_read_page(struct z_erofs_decompress_frontend *fe, - struct page *page) + struct page *page, bool ra) { struct inode *const inode = fe->inode; struct erofs_map_blocks *const map = &fe->map; @@ -1010,6 +1013,7 @@ static int z_erofs_do_read_page(struct z_erofs_decompress_frontend *fe, err = z_erofs_pcluster_begin(fe); if (err) goto out; + fe->pcl->besteffort |= !ra; } /* @@ -1276,6 +1280,9 @@ static int z_erofs_decompress_pcluster(struct z_erofs_decompress_backend *be, .inplace_io = overlapped, .partial_decoding = pcl->partial, .fillgaps = pcl->multibases, + .gfp = pcl->besteffort ? + GFP_KERNEL | __GFP_NOFAIL : + GFP_NOWAIT | __GFP_NORETRY }, be->pagepool); /* must handle all compressed pages before actual file pages */ @@ -1318,6 +1325,7 @@ static int z_erofs_decompress_pcluster(struct z_erofs_decompress_backend *be, pcl->length = 0; pcl->partial = true; pcl->multibases = false; + pcl->besteffort = false; pcl->bvset.nextpage = NULL; pcl->vcnt = 0; @@ -1787,7 +1795,7 @@ static void z_erofs_pcluster_readmore(struct z_erofs_decompress_frontend *f, if (PageUptodate(page)) unlock_page(page); else - (void)z_erofs_do_read_page(f, page); + (void)z_erofs_do_read_page(f, page, !!rac); put_page(page); } @@ -1808,7 +1816,7 @@ static int z_erofs_read_folio(struct file *file, struct folio *folio) f.headoffset = (erofs_off_t)folio->index << PAGE_SHIFT; z_erofs_pcluster_readmore(&f, NULL, true); - err = z_erofs_do_read_page(&f, &folio->page); + err = z_erofs_do_read_page(&f, &folio->page, false); z_erofs_pcluster_readmore(&f, NULL, false); z_erofs_pcluster_end(&f); @@ -1849,7 +1857,7 @@ static void z_erofs_readahead(struct readahead_control *rac) folio = head; head = folio_get_private(folio); - err = z_erofs_do_read_page(&f, &folio->page); + err = z_erofs_do_read_page(&f, &folio->page, true); if (err && err != -EINTR) erofs_err(inode->i_sb, "readahead error at folio %lu @ nid %llu", folio->index, EROFS_I(inode)->nid);