xfs: use generic Posix ACL code

This patch rips out the XFS ACL handling code and uses the generic
fs/posix_acl.c code instead.  The ondisk format is of course left
unchanged.

This also introduces the same ACL caching all other Linux filesystems do
by adding pointers to the acl and default acl in struct xfs_inode.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Eric Sandeen <sandeen@sandeen.net>

fs/xfs/Kconfig

@@ -39,6 +39,7 @@ config XFS_QUOTA
 config XFS_POSIX_ACL
 	bool "XFS POSIX ACL support"
 	depends on XFS_FS
+	select FS_POSIX_ACL
 	help
 	  POSIX Access Control Lists (ACLs) support permissions for users and
 	  groups beyond the owner/group/world scheme.

fs/xfs/Makefile

@@ -40,7 +40,7 @@ xfs-$(CONFIG_PROC_FS)		+= quota/xfs_qm_stats.o
 endif
 
 xfs-$(CONFIG_XFS_RT)		+= xfs_rtalloc.o
-xfs-$(CONFIG_XFS_POSIX_ACL)	+= xfs_acl.o
+xfs-$(CONFIG_XFS_POSIX_ACL)	+= $(XFS_LINUX)/xfs_acl.o
 xfs-$(CONFIG_PROC_FS)		+= $(XFS_LINUX)/xfs_stats.o
 xfs-$(CONFIG_SYSCTL)		+= $(XFS_LINUX)/xfs_sysctl.o
 xfs-$(CONFIG_COMPAT)		+= $(XFS_LINUX)/xfs_ioctl32.o