Merge tag 'erofs-for-5.7-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs

Pull erofs updates from Gao Xiang:
 "Updates with a XArray adaptation, several fixes for shrinker and
  corrupted images are ready for this cycle.

  All commits have been stress tested with no noticeable smoke out and
  have been in linux-next as well.

  Summary:

   - Convert radix tree usage to XArray

   - Fix shrink scan count on multiple filesystem instances

   - Better handling for specific corrupted images

   - Update my email address in MAINTAINERS"

* tag 'erofs-for-5.7-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs:
  MAINTAINERS: erofs: update my email address
  erofs: handle corrupted images whose decompressed size less than it'd be
  erofs: use LZ4_decompress_safe() for full decoding
  erofs: correct the remaining shrink objects
  erofs: convert workstn to XArray

6 files changed, 94 insertions, 106 deletions

diff --git a/MAINTAINERS b/MAINTAINERS
index 953478c9a2eb..bbec6933a4b1 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -6248,7 +6248,7 @@ F:	drivers/video/fbdev/s1d13xxxfb.c
 F:	include/video/s1d13xxxfb.h
 
 EROFS FILE SYSTEM
-M:	Gao Xiang <gaoxiang25@huawei.com>
+M:	Gao Xiang <xiang@kernel.org>
 M:	Chao Yu <yuchao0@huawei.com>
 L:	linux-erofs@lists.ozlabs.org
 S:	Maintained
diff --git a/fs/erofs/decompressor.c b/fs/erofs/decompressor.c
index 5779a15c2cd6..5d2d81940679 100644
--- a/fs/erofs/decompressor.c
+++ b/fs/erofs/decompressor.c
@@ -157,17 +157,27 @@ static int z_erofs_lz4_decompress(struct z_erofs_decompress_req *rq, u8 *out)
 		}
 	}
 
-	ret = LZ4_decompress_safe_partial(src + inputmargin, out,
-					  inlen, rq->outputsize,
-					  rq->outputsize);
-	if (ret < 0) {
-		erofs_err(rq->sb, "failed to decompress, in[%u, %u] out[%u]",
-			  inlen, inputmargin, rq->outputsize);
+	/* legacy format could compress extra data in a pcluster. */
+	if (rq->partial_decoding || !support_0padding)
+		ret = LZ4_decompress_safe_partial(src + inputmargin, out,
+						  inlen, rq->outputsize,
+						  rq->outputsize);
+	else
+		ret = LZ4_decompress_safe(src + inputmargin, out,
+					  inlen, rq->outputsize);
+
+	if (ret != rq->outputsize) {
+		erofs_err(rq->sb, "failed to decompress %d in[%u, %u] out[%u]",
+			  ret, inlen, inputmargin, rq->outputsize);
+
 		WARN_ON(1);
 		print_hex_dump(KERN_DEBUG, "[ in]: ", DUMP_PREFIX_OFFSET,
 			       16, 1, src + inputmargin, inlen, true);
 		print_hex_dump(KERN_DEBUG, "[out]: ", DUMP_PREFIX_OFFSET,
 			       16, 1, out, rq->outputsize, true);
+
+		if (ret >= 0)
+			memset(out + ret, 0, rq->outputsize - ret);
 		ret = -EIO;
 	}
 
diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
index c4c6dcdc89ad..5eead7fdc7a6 100644
--- a/fs/erofs/internal.h
+++ b/fs/erofs/internal.h
@@ -52,8 +52,8 @@ struct erofs_sb_info {
 	struct list_head list;
 	struct mutex umount_mutex;
 
-	/* the dedicated workstation for compression */
-	struct radix_tree_root workstn_tree;
+	/* managed XArray arranged in physical block number */
+	struct xarray managed_pslots;
 
 	/* threshold for decompression synchronously */
 	unsigned int max_sync_decompress_pages;
@@ -402,8 +402,8 @@ static inline void *erofs_get_pcpubuf(unsigned int pagenr)
 int erofs_workgroup_put(struct erofs_workgroup *grp);
 struct erofs_workgroup *erofs_find_workgroup(struct super_block *sb,
 					     pgoff_t index);
-int erofs_register_workgroup(struct super_block *sb,
-			     struct erofs_workgroup *grp);
+struct erofs_workgroup *erofs_insert_workgroup(struct super_block *sb,
+					       struct erofs_workgroup *grp);
 void erofs_workgroup_free_rcu(struct erofs_workgroup *grp);
 void erofs_shrinker_register(struct super_block *sb);
 void erofs_shrinker_unregister(struct super_block *sb);
diff --git a/fs/erofs/super.c b/fs/erofs/super.c
index 057e6d7b5b7f..b514c67e5fc2 100644
--- a/fs/erofs/super.c
+++ b/fs/erofs/super.c
@@ -425,7 +425,7 @@ static int erofs_fill_super(struct super_block *sb, void *data, int silent)
 		sb->s_flags &= ~SB_POSIXACL;
 
 #ifdef CONFIG_EROFS_FS_ZIP
-	INIT_RADIX_TREE(&sbi->workstn_tree, GFP_ATOMIC);
+	xa_init(&sbi->managed_pslots);
 #endif
 
 	/* get the root inode */
diff --git a/fs/erofs/utils.c b/fs/erofs/utils.c
index fddc5059c930..52d0be10f1aa 100644
--- a/fs/erofs/utils.c
+++ b/fs/erofs/utils.c
@@ -37,9 +37,6 @@ void *erofs_get_pcpubuf(unsigned int pagenr)
 /* global shrink count (for all mounted EROFS instances) */
 static atomic_long_t erofs_global_shrink_cnt;
 
-#define __erofs_workgroup_get(grp)	atomic_inc(&(grp)->refcount)
-#define __erofs_workgroup_put(grp)	atomic_dec(&(grp)->refcount)
-
 static int erofs_workgroup_get(struct erofs_workgroup *grp)
 {
 	int o;
@@ -66,7 +63,7 @@ struct erofs_workgroup *erofs_find_workgroup(struct super_block *sb,
 
 repeat:
 	rcu_read_lock();
-	grp = radix_tree_lookup(&sbi->workstn_tree, index);
+	grp = xa_load(&sbi->managed_pslots, index);
 	if (grp) {
 		if (erofs_workgroup_get(grp)) {
 			/* prefer to relax rcu read side */
@@ -80,43 +77,37 @@ repeat:
 	return grp;
 }
 
-int erofs_register_workgroup(struct super_block *sb,
-			     struct erofs_workgroup *grp)
+struct erofs_workgroup *erofs_insert_workgroup(struct super_block *sb,
+					       struct erofs_workgroup *grp)
 {
-	struct erofs_sb_info *sbi;
-	int err;
-
-	/* grp shouldn't be broken or used before */
-	if (atomic_read(&grp->refcount) != 1) {
-		DBG_BUGON(1);
-		return -EINVAL;
-	}
-
-	err = radix_tree_preload(GFP_NOFS);
-	if (err)
-		return err;
-
-	sbi = EROFS_SB(sb);
-	xa_lock(&sbi->workstn_tree);
+	struct erofs_sb_info *const sbi = EROFS_SB(sb);
+	struct erofs_workgroup *pre;
 
 	/*
-	 * Bump up reference count before making this workgroup
-	 * visible to other users in order to avoid potential UAF
-	 * without serialized by workstn_lock.
+	 * Bump up a reference count before making this visible
+	 * to others for the XArray in order to avoid potential
+	 * UAF without serialized by xa_lock.
 	 */
-	__erofs_workgroup_get(grp);
-
-	err = radix_tree_insert(&sbi->workstn_tree, grp->index, grp);
-	if (err)
-		/*
-		 * it's safe to decrease since the workgroup isn't visible
-		 * and refcount >= 2 (cannot be freezed).
-		 */
-		__erofs_workgroup_put(grp);
+	atomic_inc(&grp->refcount);
 
-	xa_unlock(&sbi->workstn_tree);
-	radix_tree_preload_end();
-	return err;
+repeat:
+	xa_lock(&sbi->managed_pslots);
+	pre = __xa_cmpxchg(&sbi->managed_pslots, grp->index,
+			   NULL, grp, GFP_NOFS);
+	if (pre) {
+		if (xa_is_err(pre)) {
+			pre = ERR_PTR(xa_err(pre));
+		} else if (erofs_workgroup_get(pre)) {
+			/* try to legitimize the current in-tree one */
+			xa_unlock(&sbi->managed_pslots);
+			cond_resched();
+			goto repeat;
+		}
+		atomic_dec(&grp->refcount);
+		grp = pre;
+	}
+	xa_unlock(&sbi->managed_pslots);
+	return grp;
 }
 
 static void  __erofs_workgroup_free(struct erofs_workgroup *grp)
@@ -155,7 +146,7 @@ static bool erofs_try_to_release_workgroup(struct erofs_sb_info *sbi,
 
 	/*
 	 * Note that all cached pages should be unattached
-	 * before deleted from the radix tree. Otherwise some
+	 * before deleted from the XArray. Otherwise some
 	 * cached pages could be still attached to the orphan
 	 * old workgroup when the new one is available in the tree.
 	 */
@@ -169,7 +160,7 @@ static bool erofs_try_to_release_workgroup(struct erofs_sb_info *sbi,
 	 * however in order to avoid some race conditions, add a
 	 * DBG_BUGON to observe this in advance.
 	 */
-	DBG_BUGON(radix_tree_delete(&sbi->workstn_tree, grp->index) != grp);
+	DBG_BUGON(xa_erase(&sbi->managed_pslots, grp->index) != grp);
 
 	/*
 	 * If managed cache is on, last refcount should indicate
@@ -182,22 +173,11 @@ static bool erofs_try_to_release_workgroup(struct erofs_sb_info *sbi,
 static unsigned long erofs_shrink_workstation(struct erofs_sb_info *sbi,
 					      unsigned long nr_shrink)
 {
-	pgoff_t first_index = 0;
-	void *batch[PAGEVEC_SIZE];
+	struct erofs_workgroup *grp;
 	unsigned int freed = 0;
+	unsigned long index;
 
-	int i, found;
-repeat:
-	xa_lock(&sbi->workstn_tree);
-
-	found = radix_tree_gang_lookup(&sbi->workstn_tree,
-				       batch, first_index, PAGEVEC_SIZE);
-
-	for (i = 0; i < found; ++i) {
-		struct erofs_workgroup *grp = batch[i];
-
-		first_index = grp->index + 1;
-
+	xa_for_each(&sbi->managed_pslots, index, grp) {
 		/* try to shrink each valid workgroup */
 		if (!erofs_try_to_release_workgroup(sbi, grp))
 			continue;
@@ -206,10 +186,6 @@ repeat:
 		if (!--nr_shrink)
 			break;
 	}
-	xa_unlock(&sbi->workstn_tree);
-
-	if (i && nr_shrink)
-		goto repeat;
 	return freed;
 }
 
@@ -286,7 +262,7 @@ static unsigned long erofs_shrink_scan(struct shrinker *shrink,
 		spin_unlock(&erofs_sb_list_lock);
 		sbi->shrinker_run_no = run_no;
 
-		freed += erofs_shrink_workstation(sbi, nr);
+		freed += erofs_shrink_workstation(sbi, nr - freed);
 
 		spin_lock(&erofs_sb_list_lock);
 		/* Get the next list element before we move this one */
diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c
index 80e47f07d946..c4b6c9aa87ec 100644
--- a/fs/erofs/zdata.c
+++ b/fs/erofs/zdata.c
@@ -67,16 +67,6 @@ static void z_erofs_pcluster_init_once(void *ptr)
 		pcl->compressed_pages[i] = NULL;
 }
 
-static void z_erofs_pcluster_init_always(struct z_erofs_pcluster *pcl)
-{
-	struct z_erofs_collection *cl = z_erofs_primarycollection(pcl);
-
-	atomic_set(&pcl->obj.refcount, 1);
-
-	DBG_BUGON(cl->nr_pages);
-	DBG_BUGON(cl->vcnt);
-}
-
 int __init z_erofs_init_zip_subsystem(void)
 {
 	pcluster_cachep = kmem_cache_create("erofs_compress",
@@ -341,26 +331,19 @@ static int z_erofs_lookup_collection(struct z_erofs_collector *clt,
 				     struct inode *inode,
 				     struct erofs_map_blocks *map)
 {
-	struct erofs_workgroup *grp;
-	struct z_erofs_pcluster *pcl;
+	struct z_erofs_pcluster *pcl = clt->pcl;
 	struct z_erofs_collection *cl;
 	unsigned int length;
 
-	grp = erofs_find_workgroup(inode->i_sb, map->m_pa >> PAGE_SHIFT);
-	if (!grp)
-		return -ENOENT;
-
-	pcl = container_of(grp, struct z_erofs_pcluster, obj);
+	/* to avoid unexpected loop formed by corrupted images */
 	if (clt->owned_head == &pcl->next || pcl == clt->tailpcl) {
 		DBG_BUGON(1);
-		erofs_workgroup_put(grp);
 		return -EFSCORRUPTED;
 	}
 
 	cl = z_erofs_primarycollection(pcl);
 	if (cl->pageofs != (map->m_la & ~PAGE_MASK)) {
 		DBG_BUGON(1);
-		erofs_workgroup_put(grp);
 		return -EFSCORRUPTED;
 	}
 
@@ -368,7 +351,6 @@ static int z_erofs_lookup_collection(struct z_erofs_collector *clt,
 	if (length & Z_EROFS_PCLUSTER_FULL_LENGTH) {
 		if ((map->m_llen << Z_EROFS_PCLUSTER_LENGTH_BIT) > length) {
 			DBG_BUGON(1);
-			erofs_workgroup_put(grp);
 			return -EFSCORRUPTED;
 		}
 	} else {
@@ -391,7 +373,6 @@ static int z_erofs_lookup_collection(struct z_erofs_collector *clt,
 	/* clean tailpcl if the current owned_head is Z_EROFS_PCLUSTER_TAIL */
 	if (clt->owned_head == Z_EROFS_PCLUSTER_TAIL)
 		clt->tailpcl = NULL;
-	clt->pcl = pcl;
 	clt->cl = cl;
 	return 0;
 }
@@ -402,6 +383,7 @@ static int z_erofs_register_collection(struct z_erofs_collector *clt,
 {
 	struct z_erofs_pcluster *pcl;
 	struct z_erofs_collection *cl;
+	struct erofs_workgroup *grp;
 	int err;
 
 	/* no available workgroup, let's allocate one */
@@ -409,7 +391,7 @@ static int z_erofs_register_collection(struct z_erofs_collector *clt,
 	if (!pcl)
 		return -ENOMEM;
 
-	z_erofs_pcluster_init_always(pcl);
+	atomic_set(&pcl->obj.refcount, 1);
 	pcl->obj.index = map->m_pa >> PAGE_SHIFT;
 
 	pcl->length = (map->m_llen << Z_EROFS_PCLUSTER_LENGTH_BIT) |
@@ -429,19 +411,29 @@ static int z_erofs_register_collection(struct z_erofs_collector *clt,
 	clt->mode = COLLECT_PRIMARY_FOLLOWED;
 
 	cl = z_erofs_primarycollection(pcl);
+
+	/* must be cleaned before freeing to slab */
+	DBG_BUGON(cl->nr_pages);
+	DBG_BUGON(cl->vcnt);
+
 	cl->pageofs = map->m_la & ~PAGE_MASK;
 
 	/*
 	 * lock all primary followed works before visible to others
 	 * and mutex_trylock *never* fails for a new pcluster.
 	 */
-	mutex_trylock(&cl->lock);
+	DBG_BUGON(!mutex_trylock(&cl->lock));
 
-	err = erofs_register_workgroup(inode->i_sb, &pcl->obj);
-	if (err) {
-		mutex_unlock(&cl->lock);
-		kmem_cache_free(pcluster_cachep, pcl);
-		return -EAGAIN;
+	grp = erofs_insert_workgroup(inode->i_sb, &pcl->obj);
+	if (IS_ERR(grp)) {
+		err = PTR_ERR(grp);
+		goto err_out;
+	}
+
+	if (grp != &pcl->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)
@@ -450,12 +442,18 @@ static int z_erofs_register_collection(struct z_erofs_collector *clt,
 	clt->pcl = pcl;
 	clt->cl = cl;
 	return 0;
+
+err_out:
+	mutex_unlock(&cl->lock);
+	kmem_cache_free(pcluster_cachep, pcl);
+	return err;
 }
 
 static int z_erofs_collector_begin(struct z_erofs_collector *clt,
 				   struct inode *inode,
 				   struct erofs_map_blocks *map)
 {
+	struct erofs_workgroup *grp;
 	int ret;
 
 	DBG_BUGON(clt->cl);
@@ -469,21 +467,25 @@ static int z_erofs_collector_begin(struct z_erofs_collector *clt,
 		return -EINVAL;
 	}
 
-repeat:
-	ret = z_erofs_lookup_collection(clt, inode, map);
-	if (ret == -ENOENT) {
+	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 {
 		ret = z_erofs_register_collection(clt, inode, map);
 
-		/* someone registered at the same time, give another try */
-		if (ret == -EAGAIN) {
-			cond_resched();
-			goto repeat;
-		}
+		if (!ret)
+			goto out;
+		if (ret != -EEXIST)
+			return ret;
 	}
 
-	if (ret)
+	ret = z_erofs_lookup_collection(clt, inode, map);
+	if (ret) {
+		erofs_workgroup_put(&clt->pcl->obj);
 		return ret;
+	}
 
+out:
 	z_erofs_pagevec_ctor_init(&clt->vector, Z_EROFS_NR_INLINE_PAGEVECS,
 				  clt->cl->pagevec, clt->cl->vcnt);