erofs_buf: store address_space instead of inode

... seeing that ->i_mapping is the only thing we want from the inode.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/erofs/data.c

@@ -32,7 +32,6 @@ void erofs_put_metabuf(struct erofs_buf *buf)
 void *erofs_bread(struct erofs_buf *buf, erofs_off_t offset,
 		  enum erofs_kmap_type type)
 {
-	struct inode *inode = buf->inode;
 	pgoff_t index = offset >> PAGE_SHIFT;
 	struct page *page = buf->page;
 	struct folio *folio;
@@ -42,7 +41,7 @@ void *erofs_bread(struct erofs_buf *buf, erofs_off_t offset,
 		erofs_put_metabuf(buf);
 
 		nofs_flag = memalloc_nofs_save();
-		folio = read_cache_folio(inode->i_mapping, index, NULL, NULL);
+		folio = read_cache_folio(buf->mapping, index, NULL, NULL);
 		memalloc_nofs_restore(nofs_flag);
 		if (IS_ERR(folio))
 			return folio;
@@ -67,9 +66,9 @@ void *erofs_bread(struct erofs_buf *buf, erofs_off_t offset,
 void erofs_init_metabuf(struct erofs_buf *buf, struct super_block *sb)
 {
 	if (erofs_is_fscache_mode(sb))
-		buf->inode = EROFS_SB(sb)->s_fscache->inode;
+		buf->mapping = EROFS_SB(sb)->s_fscache->inode->i_mapping;
 	else
-		buf->inode = sb->s_bdev->bd_inode;
+		buf->mapping = sb->s_bdev->bd_inode->i_mapping;
 }
 
 void *erofs_read_metabuf(struct erofs_buf *buf, struct super_block *sb,

fs/erofs/dir.c

@@ -58,7 +58,7 @@ static int erofs_readdir(struct file *f, struct dir_context *ctx)
 	int err = 0;
 	bool initial = true;
 
-	buf.inode = dir;
+	buf.mapping = dir->i_mapping;
 	while (ctx->pos < dirsize) {
 		struct erofs_dirent *de;
 		unsigned int nameoff, maxsize;

fs/erofs/internal.h

@@ -223,7 +223,7 @@ enum erofs_kmap_type {
 };
 
 struct erofs_buf {
-	struct inode *inode;
+	struct address_space *mapping;
 	struct page *page;
 	void *base;
 	enum erofs_kmap_type kmap_type;

fs/erofs/namei.c

@@ -99,7 +99,7 @@ static void *erofs_find_target_block(struct erofs_buf *target,
 		struct erofs_buf buf = __EROFS_BUF_INITIALIZER;
 		struct erofs_dirent *de;
 
-		buf.inode = dir;
+		buf.mapping = dir->i_mapping;
 		de = erofs_bread(&buf, erofs_pos(dir->i_sb, mid), EROFS_KMAP);
 		if (!IS_ERR(de)) {
 			const int nameoff = nameoff_from_disk(de->nameoff, bsz);
@@ -171,7 +171,7 @@ int erofs_namei(struct inode *dir, const struct qstr *name, erofs_nid_t *nid,
 
 	qn.name = name->name;
 	qn.end = name->name + name->len;
-	buf.inode = dir;
+	buf.mapping = dir->i_mapping;
 
 	ndirents = 0;
 	de = erofs_find_target_block(&buf, dir, &qn, &ndirents);

fs/erofs/xattr.c

@@ -483,7 +483,7 @@ int erofs_xattr_prefixes_init(struct super_block *sb)
 		return -ENOMEM;
 
 	if (sbi->packed_inode)
-		buf.inode = sbi->packed_inode;
+		buf.mapping = sbi->packed_inode->i_mapping;
 	else
 		erofs_init_metabuf(&buf, sb);
 

fs/erofs/zdata.c

@@ -936,7 +936,7 @@ static int z_erofs_read_fragment(struct super_block *sb, struct page *page,
 	if (!packed_inode)
 		return -EFSCORRUPTED;
 
-	buf.inode = packed_inode;
+	buf.mapping = packed_inode->i_mapping;
 	for (; cur < end; cur += cnt, pos += cnt) {
 		cnt = min_t(unsigned int, end - cur,
 			    sb->s_blocksize - erofs_blkoff(sb, pos));