One example of complete setattr code path:

fs/open.c:sys_chmod(): downs the i_sem and sets up a struct iattr:

struct iattr {
	unsigned int    ia_valid;
	umode_t         ia_mode;
	uid_t           ia_uid;
	gid_t           ia_gid;
	loff_t          ia_size;
	struct timespec ia_atime;
	struct timespec ia_mtime;
	struct timespec ia_ctime;
	unsigned int    ia_attr_flags;
};

setting ia_mode and setting ia_valid to ATTR_MODE | ATTR_CTIME.

It calls notify_change with newattr with the above struture and a dentry.  The
first thing notify_change does is update ia_ctime unconditionally.  Then it
ends up calling the setattr op.  After that, for certain attribute updates, it
calls dnotify_parent.

The nfs setattr op takes the BKL throughout.  It first calls
nfs_revalidate_inode, which may return without doing anything if jiffies is
before NFS_READTIME(inode)+NFSATTRTIMEO(inode). (Question: how are these two
times set?); otherwise it will call __nfs_revalidate_inode, which calls the
protocol-specific getattr and then calls nfs_refresh_inode to update the inode
with the results.

After calling nfs_revalidate_inode, if S_ISREG, does filemap_fdatawrite,
nfs_wb_all, and filemap_fdatawait, so we don't continue till all data is
written back.  Then it calls protocol-specific setattr.

After the rpc call, calls vmtruncate if the size changed.

If !(fattr.valid & NFS_ATTR_WCC), ets fattr.pre_size, mtime, ctime to values
from inode.  Calls NFS_CACHEINV to set NFS_READTIME to a long time ago.
Finally, calls nfs_refresh_inode(), which calls __nfs_refresh_inode().

__nfs_refresh_inode:
	If fattr->timestamp is too old, return without doing anything.
	If size has changed or mtime has changed or v4 change_attr has
	  changed, update; unless some wcc checks pass.  Update the
	  inode, update attrtimeo values.