Hi,
On Mon, Aug 17, 2009 at 11:44:59PM +0300, Sergiu Ivanov wrote:
> I think that file_syncfs is equivalent to fsys_syncfs, the difference
> being in the target of invocation (file_syncfs is invoked on a port to
> a file, while fsys_syncfs is invoked on the control port).
Yeah, that's my understanding as well.
> It looks as though the existence of both RPCs were indeed motivated by
> the necessity of solving the problem Fredrik pointed out (syncing
> filesystems of which you are not an owner).
Probably.
> diff --git a/netfs.c b/netfs.c
> index 89d1bf6..0180b1a 100644
> --- a/netfs.c
> +++ b/netfs.c
> @@ -1,5 +1,6 @@
> /* Hurd unionfs
> - Copyright (C) 2001, 2002, 2003, 2005 Free Software Foundation, Inc.
> + Copyright (C) 2001, 2002, 2003, 2005, 2009 Free Software Foundation, Inc.
> +
> Written by Moritz Schulte <mor...@duesseldorf.ccc.de>.
>
> This program is free software; you can redistribute it and/or
> @@ -282,7 +283,45 @@ error_t
> netfs_attempt_sync (struct iouser *cred, struct node *np,
> int wait)
> {
> - return EOPNOTSUPP;
> + /* The error we are going to report back (last failure wins). */
> + error_t final_err = 0;
> +
> + /* The index of the currently analyzed filesystem. */
> + int i = 0;
I think the initialization of "i" should be as close to the loop as
possible -- after all, it's a loop counter...
> +
> + /* The information about the currently analyzed filesystem. */
> + ulfs_t * ulfs;
> +
> + mutex_lock (&ulfs_lock);
> +
> + /* Sync every writable directory associated with `np`.
> +
> + TODO: Rewrite this after having modified ulfs.c and node.c to
> + store the paths and ports to the underlying directories in one
> + place, because now iterating over both lists looks ugly. */
> + node_ulfs_iterate_unlocked (np)
> + {
> + error_t err;
> +
> + /* Get the information about the current filesystem. */
> + err = ulfs_get_num (i, &ulfs);
> + assert (err == 0);
Minor nitpick: it's more common to do such checks with "!err".
> +
> + /* Since `np` may not necessarily be present in every underlying
> + directory, having a null port is perfectly valid. */
> + if ((node_ulfs->port != MACH_PORT_NULL)
> + && (ulfs->flags & FLAG_ULFS_WRITABLE))
Not sure whether I asked this before: is there actually any reason not
to attempt syncing filesystems without FLAG_ULFS_WRITABLE as well?...
(I don't know how file_sync() or file_syncfs() bahave on filesystems or
nodes that really are not writable -- but IIRC that's not what
FLAG_ULFS_WRITABLE conveys anyways?...)
> + {
> + err = file_sync (node_ulfs->port, wait, 0);
> + if (err)
> + final_err = err;
> + }
> +
> + ++i;
> + }
> +
> + mutex_unlock (&ulfs_lock);
> + return final_err;
> }
>
> /* This should sync the entire remote filesystem. If WAIT is set,
> @@ -290,7 +329,44 @@ netfs_attempt_sync (struct iouser *cred, struct node *np,
> error_t
> netfs_attempt_syncfs (struct iouser *cred, int wait)
> {
> - return 0;
> + /* The error we are going to report back (last failure wins). */
> + error_t final_err = 0;
> +
> + /* The index of the currently analyzed filesystem. */
> + int i = 0;
> +
> + /* The information about the currently analyzed filesystem. */
> + ulfs_t * ulfs;
> +
> + mutex_lock (&ulfs_lock);
> +
> + /* Sync every writable filesystem maintained by unionfs.
> +
> + TODO: Rewrite this after having modified ulfs.c and node.c to
> + store the paths and ports to the underlying directories in one
> + place, because now iterating over both lists looks ugly. */
> + node_ulfs_iterate_unlocked (netfs_root_node)
> + {
> + error_t err;
> +
> + /* Get the information about the current filesystem. */
> + err = ulfs_get_num (i, &ulfs);
> + assert (err == 0);
> +
> + /* Note that, unlike the situation in netfs_attempt_sync, having a
> + null port here is abnormal. */
Perhaps it would be helpful to state more explicitely that having a NULL
port *on the unionfs root node* is abnormal -- I didn't realize this
point at first.
(Maybe you should actually assert() this.)
> + if (ulfs->flags & FLAG_ULFS_WRITABLE)
> + {
> + err = file_syncfs (node_ulfs->port, wait, 0);
> + if (err)
> + final_err = err;
> + }
> +
> + ++i;
> + }
> +
> + mutex_unlock (&ulfs_lock);
> + return final_err;
> }
>
> /* lookup */
> --
> 1.6.3.3
-antrik-
