On Thu, Oct 15, 2009 at 03:40:29PM +1100, npiggin@xxxxxxx wrote: > Rather than keep a d_mounted count in the dentry (which is only used to > speculatively take a look in the mount hash table if it is non-zero), set a > dentry flag instead. The flag can be cleared by checking the hash table to see > if there are any mounts left. It is not time critical because it is performed > at detach time. > > This saves 4 bytes on 32-bit, nothing on 64-bit but it does provide a hole I > might use later (and some configs have larger than 32-bit spinlocks which might > make use of the hole). > > Autofs4 conversion and changelog by Ian Kent <raven@xxxxxxxxxx>: > In autofs4, when expring direct (or offset) mounts we need to ensure that we > block user path walks into the autofs mount, which is covered by another mount. > To do this we clear the mounted status so that follows stop before walking into > the mount and are essentially blocked until the expire is completed. The > automount daemon still finds the correct dentry for the umount due to the > follow mount logic in fs/autofs4/root.c:autofs4_follow_link(), which is set as > an inode operation for direct and offset mounts only and is called following > the lookup that stopped at the covered mount. > > At the end of the expire the covering mount probably has gone away so the > mounted status need not be restored. But we need to check this and only restore > the mounted status if the expire failed. > > Signed-off-by: Nick Piggin <npiggin@xxxxxxx> For the autofs4 bits. Acked-by: Ian Kent <raven@xxxxxxxxxx> -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
