erofs: support inline data decompression

Currently, we have already support tail-packing inline for
uncompressed file, let's also implement this for compressed
files to save I/Os and storage space.

Different from normal pclusters, compressed data is available
in advance because of other metadata I/Os. Therefore, they
directly move into the bypass queue without extra I/O submission.

It's the last compression feature before folio/subpage support.

Link: https://lore.kernel.org/r/20211228232919.21413-1-xiang@kernel.orgReviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Yue Hu <huyue2@yulong.com>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>

fs/erofs/zdata.c

@@ -82,12 +82,13 @@ static struct z_erofs_pcluster *z_erofs_alloc_pcluster(unsigned int nrpages)
 
 static void z_erofs_free_pcluster(struct z_erofs_pcluster *pcl)
 {
+	unsigned int pclusterpages = z_erofs_pclusterpages(pcl);
 	int i;
 
 	for (i = 0; i < ARRAY_SIZE(pcluster_pool); ++i) {
 		struct z_erofs_pcluster_slab *pcs = pcluster_pool + i;
 
-		if (pcl->pclusterpages > pcs->maxpages)
+		if (pclusterpages > pcs->maxpages)
 			continue;
 
 		kmem_cache_free(pcs->slab, pcl);
@@ -298,6 +299,7 @@ int erofs_try_to_free_all_cached_pages(struct erofs_sb_info *sbi,
 		container_of(grp, struct z_erofs_pcluster, obj);
 	int i;
 
+	DBG_BUGON(z_erofs_is_inline_pcluster(pcl));
 	/*
 	 * refcount of workgroup is now freezed as 1,
 	 * therefore no need to worry about available decompression users.
@@ -331,6 +333,7 @@ int erofs_try_to_free_cached_page(struct page *page)
 	if (erofs_workgroup_try_to_freeze(&pcl->obj, 1)) {
 		unsigned int i;
 
+		DBG_BUGON(z_erofs_is_inline_pcluster(pcl));
 		for (i = 0; i < pcl->pclusterpages; ++i) {
 			if (pcl->compressed_pages[i] == page) {
 				WRITE_ONCE(pcl->compressed_pages[i], NULL);
@@ -458,6 +461,7 @@ static int z_erofs_register_collection(struct z_erofs_collector *clt,
 				       struct inode *inode,
 				       struct erofs_map_blocks *map)
 {
+	bool ztailpacking = map->m_flags & EROFS_MAP_META;
 	struct z_erofs_pcluster *pcl;
 	struct z_erofs_collection *cl;
 	struct erofs_workgroup *grp;
@@ -469,12 +473,12 @@ static int z_erofs_register_collection(struct z_erofs_collector *clt,
 	}
 
 	/* no available pcluster, let's allocate one */
-	pcl = z_erofs_alloc_pcluster(map->m_plen >> PAGE_SHIFT);
+	pcl = z_erofs_alloc_pcluster(ztailpacking ? 1 :
+				     map->m_plen >> PAGE_SHIFT);
 	if (IS_ERR(pcl))
 		return PTR_ERR(pcl);
 
 	atomic_set(&pcl->obj.refcount, 1);
-	pcl->obj.index = map->m_pa >> PAGE_SHIFT;
 	pcl->algorithmformat = map->m_algorithmformat;
 	pcl->length = (map->m_llen << Z_EROFS_PCLUSTER_LENGTH_BIT) |
 		(map->m_flags & EROFS_MAP_FULL_MAPPED ?
@@ -494,6 +498,13 @@ static int z_erofs_register_collection(struct z_erofs_collector *clt,
 	mutex_init(&cl->lock);
 	DBG_BUGON(!mutex_trylock(&cl->lock));
 
+	if (ztailpacking) {
+		pcl->obj.index = 0;	/* which indicates ztailpacking */
+		pcl->pageofs_in = erofs_blkoff(map->m_pa);
+		pcl->tailpacking_size = map->m_plen;
+	} else {
+		pcl->obj.index = map->m_pa >> PAGE_SHIFT;
+
 		grp = erofs_insert_workgroup(inode->i_sb, &pcl->obj);
 		if (IS_ERR(grp)) {
 			err = PTR_ERR(grp);
@@ -501,10 +512,12 @@ static int z_erofs_register_collection(struct z_erofs_collector *clt,
 		}
 
 		if (grp != &pcl->obj) {
-		clt->pcl = container_of(grp, struct z_erofs_pcluster, obj);
+			clt->pcl = container_of(grp,
+					struct z_erofs_pcluster, obj);
 			err = -EEXIST;
 			goto err_out;
 		}
+	}
 	/* used to check tail merging loop due to corrupted images */
 	if (clt->owned_head == Z_EROFS_PCLUSTER_TAIL)
 		clt->tailpcl = pcl;
@@ -532,17 +545,20 @@ static int z_erofs_collector_begin(struct z_erofs_collector *clt,
 	DBG_BUGON(clt->owned_head == Z_EROFS_PCLUSTER_NIL);
 	DBG_BUGON(clt->owned_head == Z_EROFS_PCLUSTER_TAIL_CLOSED);
 
-	if (!PAGE_ALIGNED(map->m_pa)) {
+	if (map->m_flags & EROFS_MAP_META) {
+		if ((map->m_pa & ~PAGE_MASK) + map->m_plen > PAGE_SIZE) {
 			DBG_BUGON(1);
-		return -EINVAL;
+			return -EFSCORRUPTED;
+		}
+		goto tailpacking;
 	}
 
 	grp = erofs_find_workgroup(inode->i_sb, map->m_pa >> PAGE_SHIFT);
 	if (grp) {
 		clt->pcl = container_of(grp, struct z_erofs_pcluster, obj);
 	} else {
+tailpacking:
 		ret = z_erofs_register_collection(clt, inode, map);
-
 		if (!ret)
 			goto out;
 		if (ret != -EEXIST)
@@ -558,9 +574,9 @@ static int z_erofs_collector_begin(struct z_erofs_collector *clt,
 out:
 	z_erofs_pagevec_ctor_init(&clt->vector, Z_EROFS_NR_INLINE_PAGEVECS,
 				  clt->cl->pagevec, clt->cl->vcnt);
-
 	/* since file-backed online pages are traversed in reverse order */
-	clt->icpage_ptr = clt->pcl->compressed_pages + clt->pcl->pclusterpages;
+	clt->icpage_ptr = clt->pcl->compressed_pages +
+			z_erofs_pclusterpages(clt->pcl);
 	return 0;
 }
 
@@ -681,14 +697,33 @@ static int z_erofs_do_read_page(struct z_erofs_decompress_frontend *fe,
 	if (err)
 		goto err_out;
 
-	/* preload all compressed pages (maybe downgrade role if necessary) */
-	if (should_alloc_managed_pages(fe, sbi->opt.cache_strategy, map->m_la))
+	if (z_erofs_is_inline_pcluster(clt->pcl)) {
+		struct page *mpage;
+
+		mpage = erofs_get_meta_page(inode->i_sb,
+					    erofs_blknr(map->m_pa));
+		if (IS_ERR(mpage)) {
+			err = PTR_ERR(mpage);
+			erofs_err(inode->i_sb,
+				  "failed to get inline page, err %d", err);
+			goto err_out;
+		}
+		/* TODO: new subpage feature will get rid of it */
+		unlock_page(mpage);
+
+		WRITE_ONCE(clt->pcl->compressed_pages[0], mpage);
+		clt->mode = COLLECT_PRIMARY_FOLLOWED_NOINPLACE;
+	} else {
+		/* preload all compressed pages (can change mode if needed) */
+		if (should_alloc_managed_pages(fe, sbi->opt.cache_strategy,
+					       map->m_la))
 			cache_strategy = TRYALLOC;
 		else
 			cache_strategy = DONTALLOC;
 
 		preload_compressed_pages(clt, MNGD_MAPPING(sbi),
 					 cache_strategy, pagepool);
+	}
 
 hitted:
 	/*
@@ -844,6 +879,7 @@ static int z_erofs_decompress_pcluster(struct super_block *sb,
 				       struct page **pagepool)
 {
 	struct erofs_sb_info *const sbi = EROFS_SB(sb);
+	unsigned int pclusterpages = z_erofs_pclusterpages(pcl);
 	struct z_erofs_pagevec_ctor ctor;
 	unsigned int i, inputsize, outputsize, llen, nr_pages;
 	struct page *pages_onstack[Z_EROFS_VMAP_ONSTACK_PAGES];
@@ -925,15 +961,20 @@ static int z_erofs_decompress_pcluster(struct super_block *sb,
 	overlapped = false;
 	compressed_pages = pcl->compressed_pages;
 
-	for (i = 0; i < pcl->pclusterpages; ++i) {
+	for (i = 0; i < pclusterpages; ++i) {
 		unsigned int pagenr;
 
 		page = compressed_pages[i];
-
 		/* all compressed pages ought to be valid */
 		DBG_BUGON(!page);
-		DBG_BUGON(z_erofs_page_is_invalidated(page));
 
+		if (z_erofs_is_inline_pcluster(pcl)) {
+			if (!PageUptodate(page))
+				err = -EIO;
+			continue;
+		}
+
+		DBG_BUGON(z_erofs_page_is_invalidated(page));
 		if (!z_erofs_is_shortlived_page(page)) {
 			if (erofs_page_is_managed(sbi, page)) {
 				if (!PageUptodate(page))
@@ -978,11 +1019,16 @@ static int z_erofs_decompress_pcluster(struct super_block *sb,
 		partial = true;
 	}
 
-	inputsize = pcl->pclusterpages * PAGE_SIZE;
+	if (z_erofs_is_inline_pcluster(pcl))
+		inputsize = pcl->tailpacking_size;
+	else
+		inputsize = pclusterpages * PAGE_SIZE;
+
 	err = z_erofs_decompress(&(struct z_erofs_decompress_req) {
 					.sb = sb,
 					.in = compressed_pages,
 					.out = pages,
+					.pageofs_in = pcl->pageofs_in,
 					.pageofs_out = cl->pageofs,
 					.inputsize = inputsize,
 					.outputsize = outputsize,
@@ -992,8 +1038,13 @@ static int z_erofs_decompress_pcluster(struct super_block *sb,
 				 }, pagepool);
 
 out:
-	/* must handle all compressed pages before ending pages */
-	for (i = 0; i < pcl->pclusterpages; ++i) {
+	/* must handle all compressed pages before actual file pages */
+	if (z_erofs_is_inline_pcluster(pcl)) {
+		page = compressed_pages[0];
+		WRITE_ONCE(compressed_pages[0], NULL);
+		put_page(page);
+	} else {
+		for (i = 0; i < pclusterpages; ++i) {
 			page = compressed_pages[i];
 
 			if (erofs_page_is_managed(sbi, page))
@@ -1001,9 +1052,9 @@ static int z_erofs_decompress_pcluster(struct super_block *sb,
 
 			/* recycle all individual short-lived pages */
 			(void)z_erofs_put_shortlivedpage(pagepool, page);
-
 			WRITE_ONCE(compressed_pages[i], NULL);
 		}
+	}
 
 	for (i = 0; i < nr_pages; ++i) {
 		page = pages[i];
@@ -1288,6 +1339,14 @@ static void z_erofs_submit_queue(struct super_block *sb,
 
 		pcl = container_of(owned_head, struct z_erofs_pcluster, next);
 
+		/* close the main owned chain at first */
+		owned_head = cmpxchg(&pcl->next, Z_EROFS_PCLUSTER_TAIL,
+				     Z_EROFS_PCLUSTER_TAIL_CLOSED);
+		if (z_erofs_is_inline_pcluster(pcl)) {
+			move_to_bypass_jobqueue(pcl, qtail, owned_head);
+			continue;
+		}
+
 		/* no device id here, thus it will always succeed */
 		mdev = (struct erofs_map_dev) {
 			.m_pa = blknr_to_addr(pcl->obj.index),
@@ -1297,10 +1356,6 @@ static void z_erofs_submit_queue(struct super_block *sb,
 		cur = erofs_blknr(mdev.m_pa);
 		end = cur + pcl->pclusterpages;
 
-		/* close the main owned chain at first */
-		owned_head = cmpxchg(&pcl->next, Z_EROFS_PCLUSTER_TAIL,
-				     Z_EROFS_PCLUSTER_TAIL_CLOSED);
-
 		do {
 			struct page *page;
 

fs/erofs/zdata.h

@@ -62,9 +62,17 @@ struct z_erofs_pcluster {
 	/* A: lower limit of decompressed length and if full length or not */
 	unsigned int length;
 
+	/* I: page offset of inline compressed data */
+	unsigned short pageofs_in;
+
+	union {
 		/* I: physical cluster size in pages */
 		unsigned short pclusterpages;
 
+		/* I: tailpacking inline compressed size */
+		unsigned short tailpacking_size;
+	};
+
 	/* I: compression algorithm format */
 	unsigned char algorithmformat;
 
@@ -94,6 +102,18 @@ struct z_erofs_decompressqueue {
 	} u;
 };
 
+static inline bool z_erofs_is_inline_pcluster(struct z_erofs_pcluster *pcl)
+{
+	return !pcl->obj.index;
+}
+
+static inline unsigned int z_erofs_pclusterpages(struct z_erofs_pcluster *pcl)
+{
+	if (z_erofs_is_inline_pcluster(pcl))
+		return 1;
+	return pcl->pclusterpages;
+}
+
 #define Z_EROFS_ONLINEPAGE_COUNT_BITS   2
 #define Z_EROFS_ONLINEPAGE_COUNT_MASK   ((1 << Z_EROFS_ONLINEPAGE_COUNT_BITS) - 1)
 #define Z_EROFS_ONLINEPAGE_INDEX_SHIFT  (Z_EROFS_ONLINEPAGE_COUNT_BITS)