xfs: Introduce xfs_dfork_nextents() helper

This commit replaces the macro XFS_DFORK_NEXTENTS() with the helper function
xfs_dfork_nextents(). As of this commit, xfs_dfork_nextents() returns the same
value as XFS_DFORK_NEXTENTS(). A future commit which extends inode's extent
counter fields will add more logic to this helper.

This commit also replaces direct accesses to xfs_dinode->di_[a]nextents
with calls to xfs_dfork_nextents().

No functional changes have been made.
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Chandan Babu R <chandan.babu@oracle.com>

fs/xfs/libxfs/xfs_format.h

@@ -924,10 +924,6 @@ enum xfs_dinode_fmt {
 	((w) == XFS_DATA_FORK ? \
 		(dip)->di_format : \
 		(dip)->di_aformat)
-#define XFS_DFORK_NEXTENTS(dip,w) \
-	((w) == XFS_DATA_FORK ? \
-		be32_to_cpu((dip)->di_nextents) : \
-		be16_to_cpu((dip)->di_anextents))
 
 /*
  * For block and character special files the 32bit dev_t is stored at the

fs/xfs/libxfs/xfs_inode_buf.c

@@ -336,9 +336,11 @@ xfs_dinode_verify_fork(
 	struct xfs_mount	*mp,
 	int			whichfork)
 {
-	xfs_extnum_t		di_nextents = XFS_DFORK_NEXTENTS(dip, whichfork);
+	xfs_extnum_t		di_nextents;
 	xfs_extnum_t		max_extents;
 
+	di_nextents = xfs_dfork_nextents(dip, whichfork);
+
 	switch (XFS_DFORK_FORMAT(dip, whichfork)) {
 	case XFS_DINODE_FMT_LOCAL:
 		/*
@@ -405,6 +407,9 @@ xfs_dinode_verify(
 	uint16_t		flags;
 	uint64_t		flags2;
 	uint64_t		di_size;
+	xfs_extnum_t		nextents;
+	xfs_extnum_t		naextents;
+	xfs_filblks_t		nblocks;
 
 	if (dip->di_magic != cpu_to_be16(XFS_DINODE_MAGIC))
 		return __this_address;
@@ -435,10 +440,12 @@ xfs_dinode_verify(
 	if ((S_ISLNK(mode) || S_ISDIR(mode)) && di_size == 0)
 		return __this_address;
 
+	nextents = xfs_dfork_data_extents(dip);
+	naextents = xfs_dfork_attr_extents(dip);
+	nblocks = be64_to_cpu(dip->di_nblocks);
+
 	/* Fork checks carried over from xfs_iformat_fork */
-	if (mode &&
-	    be32_to_cpu(dip->di_nextents) + be16_to_cpu(dip->di_anextents) >
-			be64_to_cpu(dip->di_nblocks))
+	if (mode && nextents + naextents > nblocks)
 		return __this_address;
 
 	if (mode && XFS_DFORK_BOFF(dip) > mp->m_sb.sb_inodesize)
@@ -495,7 +502,7 @@ xfs_dinode_verify(
 		default:
 			return __this_address;
 		}
-		if (dip->di_anextents)
+		if (naextents)
 			return __this_address;
 	}
 

fs/xfs/libxfs/xfs_inode_fork.c

@@ -105,7 +105,7 @@ xfs_iformat_extents(
 	struct xfs_mount	*mp = ip->i_mount;
 	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, whichfork);
 	int			state = xfs_bmap_fork_to_state(whichfork);
-	xfs_extnum_t		nex = XFS_DFORK_NEXTENTS(dip, whichfork);
+	xfs_extnum_t		nex = xfs_dfork_nextents(dip, whichfork);
 	int			size = nex * sizeof(xfs_bmbt_rec_t);
 	struct xfs_iext_cursor	icur;
 	struct xfs_bmbt_rec	*dp;
@@ -230,7 +230,7 @@ xfs_iformat_data_fork(
 	 * depend on it.
 	 */
 	ip->i_df.if_format = dip->di_format;
-	ip->i_df.if_nextents = be32_to_cpu(dip->di_nextents);
+	ip->i_df.if_nextents = xfs_dfork_data_extents(dip);
 
 	switch (inode->i_mode & S_IFMT) {
 	case S_IFIFO:
@@ -295,14 +295,14 @@ xfs_iformat_attr_fork(
 	struct xfs_inode	*ip,
 	struct xfs_dinode	*dip)
 {
+	xfs_extnum_t		naextents = xfs_dfork_attr_extents(dip);
 	int			error = 0;
 
 	/*
 	 * Initialize the extent count early, as the per-format routines may
 	 * depend on it.
 	 */
-	ip->i_afp = xfs_ifork_alloc(dip->di_aformat,
-				be16_to_cpu(dip->di_anextents));
+	ip->i_afp = xfs_ifork_alloc(dip->di_aformat, naextents);
 
 	switch (ip->i_afp->if_format) {
 	case XFS_DINODE_FMT_LOCAL:

fs/xfs/libxfs/xfs_inode_fork.h

@@ -141,6 +141,38 @@ static inline xfs_extnum_t xfs_iext_max_nextents(int whichfork)
 	return MAXAEXTNUM;
 }
 
+static inline xfs_extnum_t
+xfs_dfork_data_extents(
+	struct xfs_dinode	*dip)
+{
+	return be32_to_cpu(dip->di_nextents);
+}
+
+static inline xfs_extnum_t
+xfs_dfork_attr_extents(
+	struct xfs_dinode	*dip)
+{
+	return be16_to_cpu(dip->di_anextents);
+}
+
+static inline xfs_extnum_t
+xfs_dfork_nextents(
+	struct xfs_dinode	*dip,
+	int			whichfork)
+{
+	switch (whichfork) {
+	case XFS_DATA_FORK:
+		return xfs_dfork_data_extents(dip);
+	case XFS_ATTR_FORK:
+		return xfs_dfork_attr_extents(dip);
+	default:
+		ASSERT(0);
+		break;
+	}
+
+	return 0;
+}
+
 struct xfs_ifork *xfs_ifork_alloc(enum xfs_dinode_fmt format,
 				xfs_extnum_t nextents);
 struct xfs_ifork *xfs_iext_state_to_fork(struct xfs_inode *ip, int state);

fs/xfs/scrub/inode.c

@@ -233,6 +233,7 @@ xchk_dinode(
 	unsigned long long	isize;
 	uint64_t		flags2;
 	xfs_extnum_t		nextents;
+	xfs_extnum_t		naextents;
 	prid_t			prid;
 	uint16_t		flags;
 	uint16_t		mode;
@@ -390,8 +391,10 @@ xchk_dinode(
 
 	xchk_inode_extsize(sc, dip, ino, mode, flags);
 
+	nextents = xfs_dfork_data_extents(dip);
+	naextents = xfs_dfork_attr_extents(dip);
+
 	/* di_nextents */
-	nextents = be32_to_cpu(dip->di_nextents);
 	fork_recs =  XFS_DFORK_DSIZE(dip, mp) / sizeof(struct xfs_bmbt_rec);
 	switch (dip->di_format) {
 	case XFS_DINODE_FMT_EXTENTS:
@@ -411,7 +414,7 @@ xchk_dinode(
 	/* di_forkoff */
 	if (XFS_DFORK_APTR(dip) >= (char *)dip + mp->m_sb.sb_inodesize)
 		xchk_ino_set_corrupt(sc, ino);
-	if (dip->di_anextents != 0 && dip->di_forkoff == 0)
+	if (naextents != 0 && dip->di_forkoff == 0)
 		xchk_ino_set_corrupt(sc, ino);
 	if (dip->di_forkoff == 0 && dip->di_aformat != XFS_DINODE_FMT_EXTENTS)
 		xchk_ino_set_corrupt(sc, ino);
@@ -423,19 +426,18 @@ xchk_dinode(
 		xchk_ino_set_corrupt(sc, ino);
 
 	/* di_anextents */
-	nextents = be16_to_cpu(dip->di_anextents);
 	fork_recs =  XFS_DFORK_ASIZE(dip, mp) / sizeof(struct xfs_bmbt_rec);
 	switch (dip->di_aformat) {
 	case XFS_DINODE_FMT_EXTENTS:
-		if (nextents > fork_recs)
+		if (naextents > fork_recs)
 			xchk_ino_set_corrupt(sc, ino);
 		break;
 	case XFS_DINODE_FMT_BTREE:
-		if (nextents <= fork_recs)
+		if (naextents <= fork_recs)
 			xchk_ino_set_corrupt(sc, ino);
 		break;
 	default:
-		if (nextents != 0)
+		if (naextents != 0)
 			xchk_ino_set_corrupt(sc, ino);
 	}
 
@@ -513,14 +515,14 @@ xchk_inode_xref_bmap(
 			&nextents, &count);
 	if (!xchk_should_check_xref(sc, &error, NULL))
 		return;
-	if (nextents < be32_to_cpu(dip->di_nextents))
+	if (nextents < xfs_dfork_data_extents(dip))
 		xchk_ino_xref_set_corrupt(sc, sc->ip->i_ino);
 
 	error = xfs_bmap_count_blocks(sc->tp, sc->ip, XFS_ATTR_FORK,
 			&nextents, &acount);
 	if (!xchk_should_check_xref(sc, &error, NULL))
 		return;
-	if (nextents != be16_to_cpu(dip->di_anextents))
+	if (nextents != xfs_dfork_attr_extents(dip))
 		xchk_ino_xref_set_corrupt(sc, sc->ip->i_ino);
 
 	/* Check nblocks against the inode. */