btrfs: initialize inode::file_extent_tree after i_mode has been set

btrfs_init_file_extent_tree() uses S_ISREG() to determine if the file is
a regular file. In the beginning of btrfs_read_locked_inode(), the i_mode
hasn't been read from inode item, then file_extent_tree won't be used at
all in volumes without NO_HOLES.

Fix this by calling btrfs_init_file_extent_tree() after i_mode is
initialized in btrfs_read_locked_inode().

Fixes: 3d7db6e ("btrfs: don't allocate file extent tree for non regular files")
CC: stable@vger.kernel.org # 6.12+
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: austinchang <austinchang@synology.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Author: austin880625syno

fs/btrfs/delayed-inode.c

@@ -1843,7 +1843,6 @@ static void fill_stack_inode_item(struct btrfs_trans_handle *trans,
 
 int btrfs_fill_inode(struct btrfs_inode *inode, u32 *rdev)
 {
-	struct btrfs_fs_info *fs_info = inode->root->fs_info;
 	struct btrfs_delayed_node *delayed_node;
 	struct btrfs_inode_item *inode_item;
 	struct inode *vfs_inode = &inode->vfs_inode;
@@ -1864,8 +1863,6 @@ int btrfs_fill_inode(struct btrfs_inode *inode, u32 *rdev)
 	i_uid_write(vfs_inode, btrfs_stack_inode_uid(inode_item));
 	i_gid_write(vfs_inode, btrfs_stack_inode_gid(inode_item));
 	btrfs_i_size_write(inode, btrfs_stack_inode_size(inode_item));
-	btrfs_inode_set_file_extent_range(inode, 0,
-			round_up(i_size_read(vfs_inode), fs_info->sectorsize));
 	vfs_inode->i_mode = btrfs_stack_inode_mode(inode_item);
 	set_nlink(vfs_inode, btrfs_stack_inode_nlink(inode_item));
 	inode_set_bytes(vfs_inode, btrfs_stack_inode_nbytes(inode_item));

fs/btrfs/inode.c

@@ -3885,10 +3885,6 @@ static int btrfs_read_locked_inode(struct btrfs_inode *inode, struct btrfs_path
 	bool filled = false;
 	int first_xattr_slot;
 
-	ret = btrfs_init_file_extent_tree(inode);
-	if (ret)
-		goto out;
-
 	ret = btrfs_fill_inode(inode, &rdev);
 	if (!ret)
 		filled = true;
@@ -3920,8 +3916,6 @@ static int btrfs_read_locked_inode(struct btrfs_inode *inode, struct btrfs_path
 	i_uid_write(vfs_inode, btrfs_inode_uid(leaf, inode_item));
 	i_gid_write(vfs_inode, btrfs_inode_gid(leaf, inode_item));
 	btrfs_i_size_write(inode, btrfs_inode_size(leaf, inode_item));
-	btrfs_inode_set_file_extent_range(inode, 0,
-			round_up(i_size_read(vfs_inode), fs_info->sectorsize));
 
 	inode_set_atime(vfs_inode, btrfs_timespec_sec(leaf, &inode_item->atime),
 			btrfs_timespec_nsec(leaf, &inode_item->atime));
@@ -3953,6 +3947,11 @@ static int btrfs_read_locked_inode(struct btrfs_inode *inode, struct btrfs_path
 	btrfs_set_inode_mapping_order(inode);
 
 cache_index:
+	ret = btrfs_init_file_extent_tree(inode);
+	if (ret)
+		goto out;
+	btrfs_inode_set_file_extent_range(inode, 0,
+			round_up(i_size_read(vfs_inode), fs_info->sectorsize));
 	/*
 	 * If we were modified in the current generation and evicted from memory
 	 * and then re-read we need to do a full sync since we don't have any