xfs: sanitise sb_bad_features2 handling

We currently have to ensure that every time we update sb_features2
that we update sb_bad_features2. Now that we log and format the
superblock in it's entirety we actually don't have to care because
we can simply update the sb_bad_features2 when we format it into the
buffer. This removes the need for anything but the mount and
superblock formatting code to care about sb_bad_features2, and
hence removes the possibility that we forget to update bad_features2
when necessary in the future.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

diff --git a/fs/xfs/libxfs/xfs_format.h b/fs/xfs/libxfs/xfs_format.h
index fbd6da2..749c861 100644 (file)
--- a/fs/xfs/libxfs/xfs_format.h
+++ b/fs/xfs/libxfs/xfs_format.h
@@ -151,10 +151,13 @@ typedef struct xfs_sb {
        __uint32_t      sb_features2;   /* additional feature bits */
 
        /*
-        * bad features2 field as a result of failing to pad the sb
-        * structure to 64 bits. Some machines will be using this field
-        * for features2 bits. Easiest just to mark it bad and not use
-        * it for anything else.
+        * bad features2 field as a result of failing to pad the sb structure to
+        * 64 bits. Some machines will be using this field for features2 bits.
+        * Easiest just to mark it bad and not use it for anything else.
+        *
+        * This is not kept up to date in memory; it is always overwritten by
+        * the value in sb_features2 when formatting the incore superblock to
+        * the disk buffer.
         */
        __uint32_t      sb_bad_features2;
 
@@ -453,13 +456,11 @@ static inline void xfs_sb_version_addattr2(struct xfs_sb *sbp)
 {
        sbp->sb_versionnum |= XFS_SB_VERSION_MOREBITSBIT;
        sbp->sb_features2 |= XFS_SB_VERSION2_ATTR2BIT;
-       sbp->sb_bad_features2 |= XFS_SB_VERSION2_ATTR2BIT;
 }
 
 static inline void xfs_sb_version_removeattr2(struct xfs_sb *sbp)
 {
        sbp->sb_features2 &= ~XFS_SB_VERSION2_ATTR2BIT;
-       sbp->sb_bad_features2 &= ~XFS_SB_VERSION2_ATTR2BIT;
        if (!sbp->sb_features2)
                sbp->sb_versionnum &= ~XFS_SB_VERSION_MOREBITSBIT;
 }
@@ -475,7 +476,6 @@ static inline void xfs_sb_version_addprojid32bit(struct xfs_sb *sbp)
 {
        sbp->sb_versionnum |= XFS_SB_VERSION_MOREBITSBIT;
        sbp->sb_features2 |= XFS_SB_VERSION2_PROJID32BIT;
-       sbp->sb_bad_features2 |= XFS_SB_VERSION2_PROJID32BIT;
 }
 
 /*

diff --git a/fs/xfs/libxfs/xfs_sb.c b/fs/xfs/libxfs/xfs_sb.c
index 63f8148..b0a5fe9 100644 (file)
--- a/fs/xfs/libxfs/xfs_sb.c
+++ b/fs/xfs/libxfs/xfs_sb.c
@@ -497,7 +497,6 @@ xfs_sb_to_disk(
        to->sb_fdblocks = cpu_to_be64(from->sb_fdblocks);
        to->sb_frextents = cpu_to_be64(from->sb_frextents);
 
-
        to->sb_flags = from->sb_flags;
        to->sb_shared_vn = from->sb_shared_vn;
        to->sb_inoalignmt = cpu_to_be32(from->sb_inoalignmt);
@@ -507,6 +506,13 @@ xfs_sb_to_disk(
        to->sb_logsectlog = from->sb_logsectlog;
        to->sb_logsectsize = cpu_to_be16(from->sb_logsectsize);
        to->sb_logsunit = cpu_to_be32(from->sb_logsunit);
+
+       /*
+        * We need to ensure that bad_features2 always matches features2.
+        * Hence we enforce that here rather than having to remember to do it
+        * everywhere else that updates features2.
+        */
+       from->sb_bad_features2 = from->sb_features2;
        to->sb_features2 = cpu_to_be32(from->sb_features2);
        to->sb_bad_features2 = cpu_to_be32(from->sb_bad_features2);
 

diff --cc fs/xfs/xfs_mount.c
Simple merge