Port of 0.8.50 acl-ms-posixacl patch to 2.5

This patch (as well as the previous one) implements core ACL support
which is needed for XFS as well as ext2/3 ACL support.  It causes umask
handling to be skilled for inodes that contain POSIX acl's, so that the
original mode information can be passed down to the low-level fs code,
which will take care of handling the umask.

fs/namei.c

@@ -1279,8 +1279,9 @@ int open_namei(const char * pathname, int flag, int mode, struct nameidata *nd)
 
 	/* Negative dentry, just create the file */
 	if (!dentry->d_inode) {
-		error = vfs_create(dir->d_inode, dentry,
-				   mode & ~current->fs->umask);
+		if (!IS_POSIXACL(dir->d_inode))
+			mode &= ~current->fs->umask;
+		error = vfs_create(dir->d_inode, dentry, mode);
 		up(&dir->d_inode->i_sem);
 		dput(nd->dentry);
 		nd->dentry = dentry;
@@ -1442,6 +1443,7 @@ asmlinkage long sys_mknod(const char * filename, int mode, dev_t dev)
 	dentry = lookup_create(&nd, 0);
 	error = PTR_ERR(dentry);
 
+	if (!IS_POSIXACL(nd.dentry->d_inode))
 		mode &= ~current->fs->umask;
 	if (!IS_ERR(dentry)) {
 		switch (mode & S_IFMT) {
@@ -1508,8 +1510,9 @@ asmlinkage long sys_mkdir(const char * pathname, int mode)
 		dentry = lookup_create(&nd, 1);
 		error = PTR_ERR(dentry);
 		if (!IS_ERR(dentry)) {
-			error = vfs_mkdir(nd.dentry->d_inode, dentry,
-					  mode & ~current->fs->umask);
+			if (!IS_POSIXACL(nd.dentry->d_inode))
+				mode &= ~current->fs->umask;
+			error = vfs_mkdir(nd.dentry->d_inode, dentry, mode);
 			dput(dentry);
 		}
 		up(&nd.dentry->d_inode->i_sem);

include/linux/fs.h

@@ -110,6 +110,7 @@ extern int leases_enable, dir_notify_enable, lease_break_time;
 #define MS_MOVE		8192
 #define MS_REC		16384
 #define MS_VERBOSE	32768
+#define MS_POSIXACL	(1<<16)	/* VFS does not apply the umask */
 #define MS_ACTIVE	(1<<30)
 #define MS_NOUSER	(1<<31)
 
@@ -164,6 +165,7 @@ extern int leases_enable, dir_notify_enable, lease_break_time;
 #define IS_IMMUTABLE(inode)	((inode)->i_flags & S_IMMUTABLE)
 #define IS_NOATIME(inode)	(__IS_FLG(inode, MS_NOATIME) || ((inode)->i_flags & S_NOATIME))
 #define IS_NODIRATIME(inode)	__IS_FLG(inode, MS_NODIRATIME)
+#define IS_POSIXACL(inode)	__IS_FLG(inode, MS_POSIXACL)
 
 #define IS_DEADDIR(inode)	((inode)->i_flags & S_DEAD)