| title: | Re PATCH 12 32 Unionfs documentation upda |
|
On Mon, Sep 03, 2007 at 08:59:02AM +0200, Jan Engelhardt wrote:
On Sep 2 2007 22:20, Josef Jeff Sipek wrote:
+
+While rebuilding Unionfss objects, we also purge any page mappings and
+truncate inode pages (see fs/Unionfs/dentry.c:purge_inode_data). This is to
fs/unionfs/dentry.c
+Unionfs maintains the following important invariant regarding mtimes,
+ctimes, and atimes: the upper inode objects times are the max() of all of
utimes, ctimes and atimes.
+2. Lockdep (a debugging feature) isnt aware of stacking, and so it
+ incorrectly complains about locking problems. The problem boils down to
+ this: Lockdep considers all objects of a certain type to be in the same
+ class, for example, all inodes. Lockdep doesnt like to see a lock held
+ on two inodes within the same task, and warns that it could lead to a
+ deadlock. However, stackable file systems do precisely that: they lock
+ an upper object, and then a lower object, in a strict order to avoid
+ locking problems; in addition, Unionfs, as a fan-out file system, may
+ have to lock several lower inodes. We are currently looking into Lockdep
+ to see how to make it aware of stackable file systems. In the mean time,
meantime
@@ -86,5 +86,12 @@ command:
# mount -t unionfs -o remount,incgen none MOUNTPOINT
+Note that the older way of incrementing the generation number using an
+ioctl, is no longer supported in Unionfs 2.0. Ioctls in general are not
2.1?
Thanks.
Jeff.
--
Penguin : Linux version 2.4.20-46.9.legacysmp on an i386 machine (2778.72 BogoMips).
-
To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at rel="nofollow" vger.kernel.org/majordomo-info.html vger.kernel.org/majordomo-info.html
|
