[PATCH] udf: fix uid/gid options and add uid/gid=ignore and forget options

Fix a bug in udf where it would write uid/gid = 0 to the disk for files
owned by the id given with the uid=/gid= mount options.  It also adds 4 new
mount options: uid/gid=forget and uid/gid=ignore.  Without any options the
id in core and on disk always match.  Giving uid/gid=nnn specifies a
default ID to be used in core when the on disk ID is -1.  uid/gid=ignore
forces the in core ID to allways be used no matter what the on disk ID is.
uid/gid=forget forces the on disk ID to always be written out as -1.

The use of these options allows you to override ownerships on a disk or
disable ownwership information from being written, allowing the media to be
used portably between different computers and possibly different users
without permissions issues that would require root to correct.

Signed-off-by: Phillip Susi <psusi@cfl.rr.com>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

fs/udf/inode.c

@@ -1045,10 +1045,14 @@ static void udf_fill_inode(struct inode *inode, struct buffer_head *bh)
 	}
 
 	inode->i_uid = le32_to_cpu(fe->uid);
-	if ( inode->i_uid == -1 ) inode->i_uid = UDF_SB(inode->i_sb)->s_uid;
+	if (inode->i_uid == -1 || UDF_QUERY_FLAG(inode->i_sb,
+					UDF_FLAG_UID_IGNORE))
+		inode->i_uid = UDF_SB(inode->i_sb)->s_uid;
 
 	inode->i_gid = le32_to_cpu(fe->gid);
-	if ( inode->i_gid == -1 ) inode->i_gid = UDF_SB(inode->i_sb)->s_gid;
+	if (inode->i_gid == -1 || UDF_QUERY_FLAG(inode->i_sb,
+					UDF_FLAG_GID_IGNORE))
+		inode->i_gid = UDF_SB(inode->i_sb)->s_gid;
 
 	inode->i_nlink = le16_to_cpu(fe->fileLinkCount);
 	if (!inode->i_nlink)
@@ -1335,10 +1339,14 @@ udf_update_inode(struct inode *inode, int do_sync)
 		return err;
 	}
 
-	if (inode->i_uid != UDF_SB(inode->i_sb)->s_uid)
+	if (UDF_QUERY_FLAG(inode->i_sb, UDF_FLAG_UID_FORGET))
+		fe->uid = cpu_to_le32(-1);
+	else if (inode->i_uid != UDF_SB(inode->i_sb)->s_uid)
 		fe->uid = cpu_to_le32(inode->i_uid);
 
-	if (inode->i_gid != UDF_SB(inode->i_sb)->s_gid)
+	if (UDF_QUERY_FLAG(inode->i_sb, UDF_FLAG_GID_FORGET))
+		fe->gid = cpu_to_le32(-1);
+	else if (inode->i_gid != UDF_SB(inode->i_sb)->s_gid)
 		fe->gid = cpu_to_le32(inode->i_gid);
 
 	udfperms =	((inode->i_mode & S_IRWXO)     ) |

fs/udf/super.c

@@ -269,7 +269,7 @@ enum {
 	Opt_gid, Opt_uid, Opt_umask, Opt_session, Opt_lastblock,
 	Opt_anchor, Opt_volume, Opt_partition, Opt_fileset,
 	Opt_rootdir, Opt_utf8, Opt_iocharset,
-	Opt_err
+	Opt_err, Opt_uforget, Opt_uignore, Opt_gforget, Opt_gignore
 };
 
 static match_table_t tokens = {
@@ -282,6 +282,10 @@ static match_table_t tokens = {
 	{Opt_adinicb, "adinicb"},
 	{Opt_shortad, "shortad"},
 	{Opt_longad, "longad"},
+	{Opt_uforget, "uid=forget"},
+	{Opt_uignore, "uid=ignore"},
+	{Opt_gforget, "gid=forget"},
+	{Opt_gignore, "gid=ignore"},
 	{Opt_gid, "gid=%u"},
 	{Opt_uid, "uid=%u"},
 	{Opt_umask, "umask=%o"},
@@ -414,6 +418,18 @@ udf_parse_options(char *options, struct udf_options *uopt)
 				uopt->flags |= (1 << UDF_FLAG_NLS_MAP);
 				break;
 #endif
+			case Opt_uignore:
+				uopt->flags |= (1 << UDF_FLAG_UID_IGNORE);
+				break;
+			case Opt_uforget:
+				uopt->flags |= (1 << UDF_FLAG_UID_FORGET);
+				break;
+			case Opt_gignore:
+			    uopt->flags |= (1 << UDF_FLAG_GID_IGNORE);
+				break;
+			case Opt_gforget:
+			    uopt->flags |= (1 << UDF_FLAG_GID_FORGET);
+				break;
 			default:
 				printk(KERN_ERR "udf: bad mount option \"%s\" "
 						"or missing value\n", p);

fs/udf/udf_sb.h

@@ -20,6 +20,10 @@
 #define UDF_FLAG_VARCONV		8
 #define UDF_FLAG_NLS_MAP		9
 #define UDF_FLAG_UTF8			10
+#define UDF_FLAG_UID_FORGET     11    /* save -1 for uid to disk */
+#define UDF_FLAG_UID_IGNORE     12    /* use sb uid instead of on disk uid */
+#define UDF_FLAG_GID_FORGET     13
+#define UDF_FLAG_GID_IGNORE     14
 
 #define UDF_PART_FLAG_UNALLOC_BITMAP	0x0001
 #define UDF_PART_FLAG_UNALLOC_TABLE	0x0002