xfs: add a new ioctl to describe allocation group geometry

Add a new ioctl to describe an allocation group's geometry.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>

1 files changed, 52 insertions, 0 deletions

diff --git a/fs/xfs/libxfs/xfs_ag.c b/fs/xfs/libxfs/xfs_ag.c
index 1ef8acf35e7d..1c0f2a6c10b4 100644
--- a/fs/xfs/libxfs/xfs_ag.c
+++ b/fs/xfs/libxfs/xfs_ag.c
@@ -19,6 +19,7 @@
 #include "xfs_ialloc.h"
 #include "xfs_rmap.h"
 #include "xfs_ag.h"
+#include "xfs_ag_resv.h"
 
 static struct xfs_buf *
 xfs_get_aghdr_buf(
@@ -461,3 +462,54 @@ xfs_ag_extend_space(
 				len, &XFS_RMAP_OINFO_SKIP_UPDATE,
 				XFS_AG_RESV_NONE);
 }
+
+/* Retrieve AG geometry. */
+int
+xfs_ag_get_geometry(
+	struct xfs_mount	*mp,
+	xfs_agnumber_t		agno,
+	struct xfs_ag_geometry	*ageo)
+{
+	struct xfs_buf		*agi_bp;
+	struct xfs_buf		*agf_bp;
+	struct xfs_agi		*agi;
+	struct xfs_agf		*agf;
+	struct xfs_perag	*pag;
+	unsigned int		freeblks;
+	int			error;
+
+	if (agno >= mp->m_sb.sb_agcount)
+		return -EINVAL;
+
+	/* Lock the AG headers. */
+	error = xfs_ialloc_read_agi(mp, NULL, agno, &agi_bp);
+	if (error)
+		return error;
+	error = xfs_alloc_read_agf(mp, NULL, agno, 0, &agf_bp);
+	if (error)
+		goto out_agi;
+	pag = xfs_perag_get(mp, agno);
+
+	/* Fill out form. */
+	memset(ageo, 0, sizeof(*ageo));
+	ageo->ag_number = agno;
+
+	agi = XFS_BUF_TO_AGI(agi_bp);
+	ageo->ag_icount = be32_to_cpu(agi->agi_count);
+	ageo->ag_ifree = be32_to_cpu(agi->agi_freecount);
+
+	agf = XFS_BUF_TO_AGF(agf_bp);
+	ageo->ag_length = be32_to_cpu(agf->agf_length);
+	freeblks = pag->pagf_freeblks +
+		   pag->pagf_flcount +
+		   pag->pagf_btreeblks -
+		   xfs_ag_resv_needed(pag, XFS_AG_RESV_NONE);
+	ageo->ag_freeblks = freeblks;
+
+	/* Release resources. */
+	xfs_perag_put(pag);
+	xfs_buf_relse(agf_bp);
+out_agi:
+	xfs_buf_relse(agi_bp);
+	return error;
+}