xfs: Enable bulkstat ioctl to support 64-bit per-inode extent counters

The following changes are made to enable userspace to obtain 64-bit extent
counters,
1. Carve out a new 64-bit field xfs_bulkstat->bs_extents64 from
   xfs_bulkstat->bs_pad[] to hold 64-bit extent counter.
2. Define the new flag XFS_BULK_IREQ_BULKSTAT for userspace to indicate that
   it is capable of receiving 64-bit extent counters.

Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Suggested-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Chandan Babu R <chandan.babu@oracle.com>

Author: Chandan Babu R

fs/xfs/libxfs/xfs_fs.h

@@ -378,7 +378,7 @@ struct xfs_bulkstat {
 	uint32_t	bs_extsize_blks; /* extent size hint, blocks	*/
 
 	uint32_t	bs_nlink;	/* number of links		*/
-	uint32_t	bs_extents;	/* number of extents		*/
+	uint32_t	bs_extents;	/* 32-bit data fork extent counter */
 	uint32_t	bs_aextents;	/* attribute number of extents	*/
 	uint16_t	bs_version;	/* structure version		*/
 	uint16_t	bs_forkoff;	/* inode fork offset in bytes	*/
@@ -387,8 +387,9 @@ struct xfs_bulkstat {
 	uint16_t	bs_checked;	/* checked inode metadata	*/
 	uint16_t	bs_mode;	/* type and mode		*/
 	uint16_t	bs_pad2;	/* zeroed			*/
+	uint64_t	bs_extents64;	/* 64-bit data fork extent counter */
 
-	uint64_t	bs_pad[7];	/* zeroed			*/
+	uint64_t	bs_pad[6];	/* zeroed			*/
 };
 
 #define XFS_BULKSTAT_VERSION_V1	(1)
@@ -460,17 +461,28 @@ struct xfs_bulk_ireq {
  * Only return results from the specified @agno.  If @ino is zero, start
  * with the first inode of @agno.
  */
-#define XFS_BULK_IREQ_AGNO	(1 << 0)
+#define XFS_BULK_IREQ_AGNO	(1U << 0)
 
 /*
  * Return bulkstat information for a single inode, where @ino value is a
  * special value, not a literal inode number.  See the XFS_BULK_IREQ_SPECIAL_*
  * values below.  Not compatible with XFS_BULK_IREQ_AGNO.
  */
-#define XFS_BULK_IREQ_SPECIAL	(1 << 1)
+#define XFS_BULK_IREQ_SPECIAL	(1U << 1)
 
-#define XFS_BULK_IREQ_FLAGS_ALL	(XFS_BULK_IREQ_AGNO | \
-				 XFS_BULK_IREQ_SPECIAL)
+/*
+ * Return data fork extent count via xfs_bulkstat->bs_extents64 field and assign
+ * 0 to xfs_bulkstat->bs_extents when the flag is set.  Otherwise, use
+ * xfs_bulkstat->bs_extents for returning data fork extent count and set
+ * xfs_bulkstat->bs_extents64 to 0. In the second case, return -EOVERFLOW and
+ * assign 0 to xfs_bulkstat->bs_extents if data fork extent count is larger than
+ * XFS_MAX_EXTCNT_DATA_FORK_OLD.
+ */
+#define XFS_BULK_IREQ_NREXT64	(1U << 2)
+
+#define XFS_BULK_IREQ_FLAGS_ALL	(XFS_BULK_IREQ_AGNO |	 \
+				 XFS_BULK_IREQ_SPECIAL | \
+				 XFS_BULK_IREQ_NREXT64)
 
 /* Operate on the root directory inode. */
 #define XFS_BULK_IREQ_SPECIAL_ROOT	(1)

fs/xfs/xfs_ioctl.c

@@ -813,6 +813,9 @@ xfs_bulk_ireq_setup(
 	if (XFS_INO_TO_AGNO(mp, breq->startino) >= mp->m_sb.sb_agcount)
 		return -ECANCELED;
 
+	if (hdr->flags & XFS_BULK_IREQ_NREXT64)
+		breq->flags |= XFS_IBULK_NREXT64;
+
 	return 0;
 }
 

fs/xfs/xfs_itable.c

@@ -64,6 +64,7 @@ xfs_bulkstat_one_int(
 	struct xfs_inode	*ip;		/* incore inode pointer */
 	struct inode		*inode;
 	struct xfs_bulkstat	*buf = bc->buf;
+	xfs_extnum_t		nextents;
 	int			error = -EINVAL;
 
 	if (xfs_internal_inum(mp, ino))
@@ -102,7 +103,13 @@ xfs_bulkstat_one_int(
 
 	buf->bs_xflags = xfs_ip2xflags(ip);
 	buf->bs_extsize_blks = ip->i_extsize;
-	buf->bs_extents = xfs_ifork_nextents(&ip->i_df);
+
+	nextents = xfs_ifork_nextents(&ip->i_df);
+	if (!(bc->breq->flags & XFS_IBULK_NREXT64))
+		buf->bs_extents = min(nextents, XFS_MAX_EXTCNT_DATA_FORK_SMALL);
+	else
+		buf->bs_extents64 = nextents;
+
 	xfs_bulkstat_health(ip, buf);
 	buf->bs_aextents = xfs_ifork_nextents(ip->i_afp);
 	buf->bs_forkoff = XFS_IFORK_BOFF(ip);

fs/xfs/xfs_itable.h

@@ -19,6 +19,9 @@ struct xfs_ibulk {
 /* Only iterate within the same AG as startino */
 #define XFS_IBULK_SAME_AG	(1U << 0)
 
+/* Fill out the bs_extents64 field if set. */
+#define XFS_IBULK_NREXT64	(1U << 1)
+
 /*
  * Advance the user buffer pointer by one record of the given size.  If the
  * buffer is now full, return the appropriate error code.