Deadlock between nfsd and snapshots.

[Kostik Belousov]

On Mon, Aug 21, 2006 at 08:37:38AM -0500, Eric Anderson wrote:
> On 08/21/06 08:21, Tor Egge wrote:
> >I wrote:
> >
> >>The deadlock indicates that one or more of IN_CHANGE, IN_MODIFIED or
> >>IN_UPDATE was set on the inode, indicating a write operation
> >>(e.g. VOP_WRITE(), VOP_RENAME(), VOP_CREATE(), VOP_REMOVE(), VOP_LINK(),
> >>VOP_SYMLINK(), VOP_SETATTR(), VOP_MKDIR(), VOP_RMDIR(), VOP_MKNOD()) that 
> >>was
> >>not protected by vn_start_write() or vn_start_secondary_write().
> >
> >The most common "write" operation was probably VOP_GETATTR().
> >
> >ufs_itimes(), called from ufs_getattr(), might set the IN_MODIFIED inode 
> >flag
> >if IN_ACCESS is set on the inode even if neither IN_CHANGE nor IN_UPDATE is
> >set, transitioning the inode flags into a state where ufs_inactive() calls 
> >the
> >blocking variant of vn_start_secondary_write().
> >
> >calling ufs_itimes() with only a shared vnode lock might cause unsafe 
> >accesses
> >to the inode flags.  Setting of IN_ACCESS at the end of ffs_read() and
> >ffs_extread() might also be unsafe.  If DIRECTIO is enabled then O_DIRECT 
> >reads
> >might not even attempt to set the IN_ACCESS flag.
> 
> Does this mean that setting the noatime flag on mount would dodge this?
On the server, yes.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 187 bytes
Desc: not available
Url : http://lists.freebsd.org/pipermail/freebsd-fs/attachments/20060821/1ac15255/attachment.pgp