[XFS] Fix up noattr2 so that it will properly update the versionnum and

features2 fields.

Previously, mounting with noattr2 failed to achieve anything because
although it cleared the attr2 mount flag, it would set it again as soon as
it processed the superblock fields. The fix now has an explicit noattr2
flag and uses it later to fix up the versionnum and features2 fields.

SGI-PV: 980021
SGI-Modid: xfs-linux-melb:xfs-kern:31003a

Signed-off-by: Tim Shimmin <tes@sgi.com>
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>

fs/xfs/linux-2.6/xfs_super.c

@@ -314,6 +314,7 @@ xfs_parseargs(
 			args->flags |= XFSMNT_ATTR2;
 		} else if (!strcmp(this_char, MNTOPT_NOATTR2)) {
 			args->flags &= ~XFSMNT_ATTR2;
+			args->flags |= XFSMNT_NOATTR2;
 		} else if (!strcmp(this_char, MNTOPT_FILESTREAM)) {
 			args->flags2 |= XFSMNT2_FILESTREAMS;
 		} else if (!strcmp(this_char, MNTOPT_NOQUOTA)) {

fs/xfs/xfs_clnt.h

@@ -78,6 +78,7 @@ struct xfs_mount_args {
 #define XFSMNT_IOSIZE		0x00002000	/* optimize for I/O size */
 #define XFSMNT_OSYNCISOSYNC	0x00004000	/* o_sync is REALLY o_sync */
 						/* (osyncisdsync is default) */
+#define XFSMNT_NOATTR2		0x00008000	/* turn off ATTR2 EA format */
 #define XFSMNT_32BITINODES	0x00200000	/* restrict inodes to 32
 						 * bits of address space */
 #define XFSMNT_GQUOTA		0x00400000	/* group quota accounting */

fs/xfs/xfs_mount.c

@@ -994,9 +994,19 @@ xfs_mountfs(
 		 * Re-check for ATTR2 in case it was found in bad_features2
 		 * slot.
 		 */
-		if (xfs_sb_version_hasattr2(&mp->m_sb))
+		if (xfs_sb_version_hasattr2(&mp->m_sb) &&
+		   !(mp->m_flags & XFS_MOUNT_NOATTR2))
 			mp->m_flags |= XFS_MOUNT_ATTR2;
+	}
 
+	if (xfs_sb_version_hasattr2(&mp->m_sb) &&
+	   (mp->m_flags & XFS_MOUNT_NOATTR2)) {
+		xfs_sb_version_removeattr2(&mp->m_sb);
+		update_flags |= XFS_SB_FEATURES2;
+
+		/* update sb_versionnum for the clearing of the morebits */
+		if (!sbp->sb_features2)
+			update_flags |= XFS_SB_VERSIONNUM;
 	}
 
 	/*

fs/xfs/xfs_mount.h

@@ -378,6 +378,7 @@ typedef struct xfs_mount {
 						   counters */
 #define XFS_MOUNT_FILESTREAMS	(1ULL << 24)	/* enable the filestreams
 						   allocator */
+#define XFS_MOUNT_NOATTR2	(1ULL << 25)	/* disable use of attr2 format */
 
 
 /*

fs/xfs/xfs_sb.h

@@ -473,6 +473,13 @@ static inline void xfs_sb_version_addattr2(xfs_sb_t *sbp)
 		((sbp)->sb_features2 | XFS_SB_VERSION2_ATTR2BIT)));
 }
 
+static inline void xfs_sb_version_removeattr2(xfs_sb_t *sbp)
+{
+	sbp->sb_features2 &= ~XFS_SB_VERSION2_ATTR2BIT;
+	if (!sbp->sb_features2)
+		sbp->sb_versionnum &= ~XFS_SB_VERSION_MOREBITSBIT;
+}
+
 /*
  * end of superblock version macros
  */

fs/xfs/xfs_vfsops.c

@@ -284,6 +284,8 @@ xfs_start_flags(
 		mp->m_flags |= XFS_MOUNT_DIRSYNC;
 	if (ap->flags & XFSMNT_ATTR2)
 		mp->m_flags |= XFS_MOUNT_ATTR2;
+	if (ap->flags & XFSMNT_NOATTR2)
+		mp->m_flags |= XFS_MOUNT_NOATTR2;
 
 	if (ap->flags2 & XFSMNT2_COMPAT_IOSIZE)
 		mp->m_flags |= XFS_MOUNT_COMPAT_IOSIZE;
@@ -346,7 +348,12 @@ xfs_finish_flags(
 		}
 	}
 
-	if (xfs_sb_version_hasattr2(&mp->m_sb))
+	/*
+	 * mkfs'ed attr2 will turn on attr2 mount unless explicitly
+	 * told by noattr2 to turn it off
+	 */
+	if (xfs_sb_version_hasattr2(&mp->m_sb) &&
+	    !(ap->flags & XFSMNT_NOATTR2))
 		mp->m_flags |= XFS_MOUNT_ATTR2;
 
 	/*