Merge tag 'erofs-for-6.12-rc4-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs

Pull erofs fixes from Gao Xiang:
 "The main one fixes a syzbot issue due to the invalid inode type out of
  file-backed mounts. The others are minor cleanups without actual logic
  changes.

  Summary:

   - Make sure only regular inodes can be used for file-backed mounts

   - Two minor codebase cleanups"

* tag 'erofs-for-6.12-rc4-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs:
  erofs: get rid of kaddr in `struct z_erofs_maprecorder`
  erofs: get rid of z_erofs_try_to_claim_pcluster()
  erofs: ensure regular inodes for file-backed mounts

fs/erofs/super.c

@@ -191,10 +191,14 @@ static int erofs_init_device(struct erofs_buf *buf, struct super_block *sb,
 		if (IS_ERR(file))
 			return PTR_ERR(file);
 
-		dif->file = file;
-		if (!erofs_is_fileio_mode(sbi))
+		if (!erofs_is_fileio_mode(sbi)) {
 			dif->dax_dev = fs_dax_get_by_bdev(file_bdev(file),
 					&dif->dax_part_off, NULL, NULL);
+		} else if (!S_ISREG(file_inode(file)->i_mode)) {
+			fput(file);
+			return -EINVAL;
+		}
+		dif->file = file;
 	}
 
 	dif->blocks = le32_to_cpu(dis->blocks);
@@ -714,7 +718,10 @@ static int erofs_fc_get_tree(struct fs_context *fc)
 		if (IS_ERR(sbi->fdev))
 			return PTR_ERR(sbi->fdev);
 
-		return get_tree_nodev(fc, erofs_fc_fill_super);
+		if (S_ISREG(file_inode(sbi->fdev)->i_mode) &&
+		    sbi->fdev->f_mapping->a_ops->read_folio)
+			return get_tree_nodev(fc, erofs_fc_fill_super);
+		fput(sbi->fdev);
 	}
 #endif
 	return ret;

fs/erofs/zdata.c

@@ -710,24 +710,6 @@ static int z_erofs_attach_page(struct z_erofs_decompress_frontend *fe,
 	return ret;
 }
 
-static void z_erofs_try_to_claim_pcluster(struct z_erofs_decompress_frontend *f)
-{
-	struct z_erofs_pcluster *pcl = f->pcl;
-	z_erofs_next_pcluster_t *owned_head = &f->owned_head;
-
-	/* type 1, nil pcluster (this pcluster doesn't belong to any chain.) */
-	if (cmpxchg(&pcl->next, Z_EROFS_PCLUSTER_NIL,
-		    *owned_head) == Z_EROFS_PCLUSTER_NIL) {
-		*owned_head = &pcl->next;
-		/* so we can attach this pcluster to our submission chain. */
-		f->mode = Z_EROFS_PCLUSTER_FOLLOWED;
-		return;
-	}
-
-	/* type 2, it belongs to an ongoing chain */
-	f->mode = Z_EROFS_PCLUSTER_INFLIGHT;
-}
-
 static int z_erofs_register_pcluster(struct z_erofs_decompress_frontend *fe)
 {
 	struct erofs_map_blocks *map = &fe->map;
@@ -803,7 +785,6 @@ static int z_erofs_pcluster_begin(struct z_erofs_decompress_frontend *fe)
 	int ret;
 
 	DBG_BUGON(fe->pcl);
-
 	/* must be Z_EROFS_PCLUSTER_TAIL or pointed to previous pcluster */
 	DBG_BUGON(fe->owned_head == Z_EROFS_PCLUSTER_NIL);
 
@@ -823,7 +804,15 @@ static int z_erofs_pcluster_begin(struct z_erofs_decompress_frontend *fe)
 
 	if (ret == -EEXIST) {
 		mutex_lock(&fe->pcl->lock);
-		z_erofs_try_to_claim_pcluster(fe);
+		/* check if this pcluster hasn't been linked into any chain. */
+		if (cmpxchg(&fe->pcl->next, Z_EROFS_PCLUSTER_NIL,
+			    fe->owned_head) == Z_EROFS_PCLUSTER_NIL) {
+			/* .. so it can be attached to our submission chain */
+			fe->owned_head = &fe->pcl->next;
+			fe->mode = Z_EROFS_PCLUSTER_FOLLOWED;
+		} else {	/* otherwise, it belongs to an inflight chain */
+			fe->mode = Z_EROFS_PCLUSTER_INFLIGHT;
+		}
 	} else if (ret) {
 		return ret;
 	}

fs/erofs/zmap.c

@@ -10,8 +10,6 @@
 struct z_erofs_maprecorder {
 	struct inode *inode;
 	struct erofs_map_blocks *map;
-	void *kaddr;
-
 	unsigned long lcn;
 	/* compression extent information gathered */
 	u8  type, headtype;
@@ -33,14 +31,11 @@ static int z_erofs_load_full_lcluster(struct z_erofs_maprecorder *m,
 	struct z_erofs_lcluster_index *di;
 	unsigned int advise;
 
-	m->kaddr = erofs_read_metabuf(&m->map->buf, inode->i_sb,
-				      pos, EROFS_KMAP);
-	if (IS_ERR(m->kaddr))
-		return PTR_ERR(m->kaddr);
-
-	m->nextpackoff = pos + sizeof(struct z_erofs_lcluster_index);
+	di = erofs_read_metabuf(&m->map->buf, inode->i_sb, pos, EROFS_KMAP);
+	if (IS_ERR(di))
+		return PTR_ERR(di);
 	m->lcn = lcn;
-	di = m->kaddr;
+	m->nextpackoff = pos + sizeof(struct z_erofs_lcluster_index);
 
 	advise = le16_to_cpu(di->di_advise);
 	m->type = advise & Z_EROFS_LI_LCLUSTER_TYPE_MASK;
@@ -53,8 +48,7 @@ static int z_erofs_load_full_lcluster(struct z_erofs_maprecorder *m,
 				DBG_BUGON(1);
 				return -EFSCORRUPTED;
 			}
-			m->compressedblks = m->delta[0] &
-				~Z_EROFS_LI_D0_CBLKCNT;
+			m->compressedblks = m->delta[0] & ~Z_EROFS_LI_D0_CBLKCNT;
 			m->delta[0] = 1;
 		}
 		m->delta[1] = le16_to_cpu(di->di_u.delta[1]);
@@ -110,9 +104,9 @@ static int unpack_compacted_index(struct z_erofs_maprecorder *m,
 	struct erofs_inode *const vi = EROFS_I(m->inode);
 	const unsigned int lclusterbits = vi->z_logical_clusterbits;
 	unsigned int vcnt, lo, lobits, encodebits, nblk, bytes;
-	int i;
-	u8 *in, type;
 	bool big_pcluster;
+	u8 *in, type;
+	int i;
 
 	if (1 << amortizedshift == 4 && lclusterbits <= 14)
 		vcnt = 2;
@@ -121,6 +115,10 @@ static int unpack_compacted_index(struct z_erofs_maprecorder *m,
 	else
 		return -EOPNOTSUPP;
 
+	in = erofs_read_metabuf(&m->map->buf, m->inode->i_sb, pos, EROFS_KMAP);
+	if (IS_ERR(in))
+		return PTR_ERR(in);
+
 	/* it doesn't equal to round_up(..) */
 	m->nextpackoff = round_down(pos, vcnt << amortizedshift) +
 			 (vcnt << amortizedshift);
@@ -128,9 +126,7 @@ static int unpack_compacted_index(struct z_erofs_maprecorder *m,
 	lobits = max(lclusterbits, ilog2(Z_EROFS_LI_D0_CBLKCNT) + 1U);
 	encodebits = ((vcnt << amortizedshift) - sizeof(__le32)) * 8 / vcnt;
 	bytes = pos & ((vcnt << amortizedshift) - 1);
-
-	in = m->kaddr - bytes;
-
+	in -= bytes;
 	i = bytes >> amortizedshift;
 
 	lo = decode_compactedbits(lobits, in, encodebits * i, &type);
@@ -255,10 +251,6 @@ static int z_erofs_load_compact_lcluster(struct z_erofs_maprecorder *m,
 	amortizedshift = 2;
 out:
 	pos += lcn * (1 << amortizedshift);
-	m->kaddr = erofs_read_metabuf(&m->map->buf, inode->i_sb,
-				      pos, EROFS_KMAP);
-	if (IS_ERR(m->kaddr))
-		return PTR_ERR(m->kaddr);
 	return unpack_compacted_index(m, amortizedshift, pos, lookahead);
 }