6.10-stable review patch. If anyone has any objections, please let me know.
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From: Gao Xiang hsiangkao@linux.alibaba.com
[ Upstream commit 2080ca1ed3e43233c4e8480c0b9d2840886de01e ]
After revisiting the design, I believe `struct z_erofs_bvec` should be page-based instead of folio-based due to the reasons below:
- The minimized memory mapping block is a page;
- Under the certain circumstances, only temporary pages needs to be used instead of folios since refcount, mapcount for such pages are unnecessary;
- Decompressors handle all types of pages including temporary pages, not only folios.
When handling `struct z_erofs_bvec`, all folio-related information is now accessed using the page_folio() helper.
The final goal of this round adaptation is to eliminate direct accesses to `struct page` in the EROFS codebase, except for some exceptions like `z_erofs_is_shortlived_page()` and `z_erofs_page_is_invalidated()`, which require a new helper to determine the memdesc type of an arbitrary page.
Actually large folios of compressed files seem to work now, yet I tend to conduct more tests before officially enabling this for all scenarios.
Signed-off-by: Gao Xiang hsiangkao@linux.alibaba.com Link: https://lore.kernel.org/r/20240703120051.3653452-4-hsiangkao@linux.alibaba.c... Stable-dep-of: 9e2f9d34dd12 ("erofs: handle overlapped pclusters out of crafted images properly") Signed-off-by: Sasha Levin sashal@kernel.org --- fs/erofs/zdata.c | 101 +++++++++++++++++++++++------------------------ 1 file changed, 49 insertions(+), 52 deletions(-)
diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c index d6fe002a4a719..d269b092c477f 100644 --- a/fs/erofs/zdata.c +++ b/fs/erofs/zdata.c @@ -19,10 +19,7 @@ typedef void *z_erofs_next_pcluster_t;
struct z_erofs_bvec { - union { - struct page *page; - struct folio *folio; - }; + struct page *page; int offset; unsigned int end; }; @@ -617,32 +614,31 @@ static void z_erofs_bind_cache(struct z_erofs_decompress_frontend *fe) fe->mode = Z_EROFS_PCLUSTER_FOLLOWED_NOINPLACE; }
-/* called by erofs_shrinker to get rid of all cached compressed bvecs */ +/* (erofs_shrinker) disconnect cached encoded data with pclusters */ int erofs_try_to_free_all_cached_folios(struct erofs_sb_info *sbi, struct erofs_workgroup *grp) { struct z_erofs_pcluster *const pcl = container_of(grp, struct z_erofs_pcluster, obj); unsigned int pclusterpages = z_erofs_pclusterpages(pcl); + struct folio *folio; int i;
DBG_BUGON(z_erofs_is_inline_pcluster(pcl)); - /* There is no actice user since the pcluster is now freezed */ + /* Each cached folio contains one page unless bs > ps is supported */ for (i = 0; i < pclusterpages; ++i) { - struct folio *folio = pcl->compressed_bvecs[i].folio; + if (pcl->compressed_bvecs[i].page) { + folio = page_folio(pcl->compressed_bvecs[i].page); + /* Avoid reclaiming or migrating this folio */ + if (!folio_trylock(folio)) + return -EBUSY;
- if (!folio) - continue; - - /* Avoid reclaiming or migrating this folio */ - if (!folio_trylock(folio)) - return -EBUSY; - - if (!erofs_folio_is_managed(sbi, folio)) - continue; - pcl->compressed_bvecs[i].folio = NULL; - folio_detach_private(folio); - folio_unlock(folio); + if (!erofs_folio_is_managed(sbi, folio)) + continue; + pcl->compressed_bvecs[i].page = NULL; + folio_detach_private(folio); + folio_unlock(folio); + } } return 0; } @@ -650,9 +646,9 @@ int erofs_try_to_free_all_cached_folios(struct erofs_sb_info *sbi, static bool z_erofs_cache_release_folio(struct folio *folio, gfp_t gfp) { struct z_erofs_pcluster *pcl = folio_get_private(folio); - unsigned int pclusterpages = z_erofs_pclusterpages(pcl); + struct z_erofs_bvec *bvec = pcl->compressed_bvecs; + struct z_erofs_bvec *end = bvec + z_erofs_pclusterpages(pcl); bool ret; - int i;
if (!folio_test_private(folio)) return true; @@ -661,9 +657,9 @@ static bool z_erofs_cache_release_folio(struct folio *folio, gfp_t gfp) spin_lock(&pcl->obj.lockref.lock); if (pcl->obj.lockref.count <= 0) { DBG_BUGON(z_erofs_is_inline_pcluster(pcl)); - for (i = 0; i < pclusterpages; ++i) { - if (pcl->compressed_bvecs[i].folio == folio) { - pcl->compressed_bvecs[i].folio = NULL; + for (; bvec < end; ++bvec) { + if (bvec->page && page_folio(bvec->page) == folio) { + bvec->page = NULL; folio_detach_private(folio); ret = true; break; @@ -1066,7 +1062,7 @@ static bool z_erofs_is_sync_decompress(struct erofs_sb_info *sbi,
static bool z_erofs_page_is_invalidated(struct page *page) { - return !page->mapping && !z_erofs_is_shortlived_page(page); + return !page_folio(page)->mapping && !z_erofs_is_shortlived_page(page); }
struct z_erofs_decompress_backend { @@ -1419,7 +1415,7 @@ static void z_erofs_fill_bio_vec(struct bio_vec *bvec, bool tocache = false; struct z_erofs_bvec zbv; struct address_space *mapping; - struct page *page; + struct folio *folio; int bs = i_blocksize(f->inode);
/* Except for inplace folios, the entire folio can be used for I/Os */ @@ -1429,23 +1425,25 @@ static void z_erofs_fill_bio_vec(struct bio_vec *bvec, spin_lock(&pcl->obj.lockref.lock); zbv = pcl->compressed_bvecs[nr]; spin_unlock(&pcl->obj.lockref.lock); - if (!zbv.folio) + if (!zbv.page) goto out_allocfolio;
- bvec->bv_page = &zbv.folio->page; + bvec->bv_page = zbv.page; DBG_BUGON(z_erofs_is_shortlived_page(bvec->bv_page)); + + folio = page_folio(zbv.page); /* * Handle preallocated cached folios. We tried to allocate such folios * without triggering direct reclaim. If allocation failed, inplace * file-backed folios will be used instead. */ - if (zbv.folio->private == (void *)Z_EROFS_PREALLOCATED_PAGE) { - zbv.folio->private = 0; + if (folio->private == (void *)Z_EROFS_PREALLOCATED_PAGE) { + folio->private = 0; tocache = true; goto out_tocache; }
- mapping = READ_ONCE(zbv.folio->mapping); + mapping = READ_ONCE(folio->mapping); /* * File-backed folios for inplace I/Os are all locked steady, * therefore it is impossible for `mapping` to be NULL. @@ -1457,21 +1455,21 @@ static void z_erofs_fill_bio_vec(struct bio_vec *bvec, return; }
- folio_lock(zbv.folio); - if (zbv.folio->mapping == mc) { + folio_lock(folio); + if (folio->mapping == mc) { /* * The cached folio is still in managed cache but without * a valid `->private` pcluster hint. Let's reconnect them. */ - if (!folio_test_private(zbv.folio)) { - folio_attach_private(zbv.folio, pcl); + if (!folio_test_private(folio)) { + folio_attach_private(folio, pcl); /* compressed_bvecs[] already takes a ref before */ - folio_put(zbv.folio); + folio_put(folio); }
/* no need to submit if it is already up-to-date */ - if (folio_test_uptodate(zbv.folio)) { - folio_unlock(zbv.folio); + if (folio_test_uptodate(folio)) { + folio_unlock(folio); bvec->bv_page = NULL; } return; @@ -1481,32 +1479,31 @@ static void z_erofs_fill_bio_vec(struct bio_vec *bvec, * It has been truncated, so it's unsafe to reuse this one. Let's * allocate a new page for compressed data. */ - DBG_BUGON(zbv.folio->mapping); + DBG_BUGON(folio->mapping); tocache = true; - folio_unlock(zbv.folio); - folio_put(zbv.folio); + folio_unlock(folio); + folio_put(folio); out_allocfolio: - page = erofs_allocpage(&f->pagepool, gfp | __GFP_NOFAIL); + zbv.page = erofs_allocpage(&f->pagepool, gfp | __GFP_NOFAIL); spin_lock(&pcl->obj.lockref.lock); - if (pcl->compressed_bvecs[nr].folio) { - erofs_pagepool_add(&f->pagepool, page); + if (pcl->compressed_bvecs[nr].page) { + erofs_pagepool_add(&f->pagepool, zbv.page); spin_unlock(&pcl->obj.lockref.lock); cond_resched(); goto repeat; } - pcl->compressed_bvecs[nr].folio = zbv.folio = page_folio(page); + bvec->bv_page = pcl->compressed_bvecs[nr].page = zbv.page; + folio = page_folio(zbv.page); + /* first mark it as a temporary shortlived folio (now 1 ref) */ + folio->private = (void *)Z_EROFS_SHORTLIVED_PAGE; spin_unlock(&pcl->obj.lockref.lock); - bvec->bv_page = page; out_tocache: if (!tocache || bs != PAGE_SIZE || - filemap_add_folio(mc, zbv.folio, pcl->obj.index + nr, gfp)) { - /* turn into a temporary shortlived folio (1 ref) */ - zbv.folio->private = (void *)Z_EROFS_SHORTLIVED_PAGE; + filemap_add_folio(mc, folio, pcl->obj.index + nr, gfp)) return; - } - folio_attach_private(zbv.folio, pcl); + folio_attach_private(folio, pcl); /* drop a refcount added by allocpage (then 2 refs in total here) */ - folio_put(zbv.folio); + folio_put(folio); }
static struct z_erofs_decompressqueue *jobqueue_init(struct super_block *sb,