svn commit: r220761 - head/sys/fs/nfsclient

[Kostik Belousov]

On Sun, Apr 17, 2011 at 11:04:04PM +0000, Rick Macklem wrote:
> Author: rmacklem
> Date: Sun Apr 17 23:04:03 2011
> New Revision: 220761
> URL: http://svn.freebsd.org/changeset/base/220761
> 
> Log:
>   Add checks for MNTK_UNMOUNTF at the beginning of three
>   functions, so that threads don't get stuck in them during
>   a forced dismount. nfs_sync/VFS_SYNC() needs this, since it is
>   called by dounmount() before VFS_UNMOUNT(). The nfscl_nget()
>   case makes sure that a thread doing an VOP_OPEN() or
>   VOP_ADVLOCK() call doesn't get blocked before attempting
>   the RPC. Attempting RPCs don't block, since they all
>   fail once a forced dismount is in progress.
>   The third one at the beginning of nfsrpc_close()
>   is done so threads don't get blocked while doing VOP_INACTIVE()
>   as the vnodes are cleared out.
>   With these three changes plus a change to the umount(1)
>   command so that it doesn't do "sync()" for the forced case
>   seem to make forced dismounts work for the experimental NFS
>   client.
>   
>   MFC after:	2 weeks
> 
> Modified:
>   head/sys/fs/nfsclient/nfs_clrpcops.c
>   head/sys/fs/nfsclient/nfs_clstate.c
>   head/sys/fs/nfsclient/nfs_clvfsops.c
> 
> Modified: head/sys/fs/nfsclient/nfs_clrpcops.c
> ==============================================================================
> --- head/sys/fs/nfsclient/nfs_clrpcops.c	Sun Apr 17 22:31:36 2011	(r220760)
> +++ head/sys/fs/nfsclient/nfs_clrpcops.c	Sun Apr 17 23:04:03 2011	(r220761)
> @@ -567,6 +567,11 @@ nfsrpc_close(vnode_t vp, int doclose, NF
>  
>  	if (vnode_vtype(vp) != VREG)
>  		return (0);
> +
> +	/* For forced unmounts, just return. */
> +	if ((vp->v_mount->mnt_kern_flag & MNTK_UNMOUNTF) != 0)
> +		return (0);
> +
Is there anything that would prevent the MNTK_UNMOUNTF flag from being
set immediately after the test returned success ?

Usually, the tests for MNTK_UNMOUNTF are bugs. I coould see how terminating
the RPCs would be useful for forced unmounts, but do not think that
preventing entry into close would help.

>  	if (doclose)
>  		error = nfscl_doclose(vp, &clp, p);
>  	else
> 
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