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>

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;
+}

fs/xfs/libxfs/xfs_ag.h

@@ -26,5 +26,7 @@ struct aghdr_init_data {
 int xfs_ag_init_headers(struct xfs_mount *mp, struct aghdr_init_data *id);
 int xfs_ag_extend_space(struct xfs_mount *mp, struct xfs_trans *tp,
 			struct aghdr_init_data *id, xfs_extlen_t len);
+int xfs_ag_get_geometry(struct xfs_mount *mp, xfs_agnumber_t agno,
+			struct xfs_ag_geometry *ageo);
 
 #endif /* __LIBXFS_AG_H */

fs/xfs/libxfs/xfs_fs.h

@@ -267,6 +267,19 @@ typedef struct xfs_fsop_resblks {
 #define XFS_MIN_DBLOCKS(s) ((xfs_rfsblock_t)((s)->sb_agcount - 1) *	\
 			 (s)->sb_agblocks + XFS_MIN_AG_BLOCKS)
 
+/*
+ * Output for XFS_IOC_AG_GEOMETRY
+ */
+struct xfs_ag_geometry {
+	uint32_t	ag_number;	/* i/o: AG number */
+	uint32_t	ag_length;	/* o: length in blocks */
+	uint32_t	ag_freeblks;	/* o: free space */
+	uint32_t	ag_icount;	/* o: inodes allocated */
+	uint32_t	ag_ifree;	/* o: inodes free */
+	uint32_t	ag_reserved32;	/* o: zero */
+	uint64_t	ag_reserved[13];/* o: zero */
+};
+
 /*
  * Structures for XFS_IOC_FSGROWFSDATA, XFS_IOC_FSGROWFSLOG & XFS_IOC_FSGROWFSRT
  */
@@ -620,6 +633,7 @@ struct xfs_scrub_metadata {
 #define XFS_IOC_FREE_EOFBLOCKS	_IOR ('X', 58, struct xfs_fs_eofblocks)
 /*	XFS_IOC_GETFSMAP ------ hoisted 59         */
 #define XFS_IOC_SCRUB_METADATA	_IOWR('X', 60, struct xfs_scrub_metadata)
+#define XFS_IOC_AG_GEOMETRY	_IOWR('X', 61, struct xfs_ag_geometry)
 
 /*
  * ioctl commands that replace IRIX syssgi()'s

fs/xfs/xfs_ioctl.c

@@ -33,6 +33,7 @@
 #include "xfs_fsmap.h"
 #include "scrub/xfs_scrub.h"
 #include "xfs_sb.h"
+#include "xfs_ag.h"
 
 #include <linux/capability.h>
 #include <linux/cred.h>
@@ -804,6 +805,26 @@ xfs_ioc_fsgeometry(
 	return 0;
 }
 
+STATIC int
+xfs_ioc_ag_geometry(
+	struct xfs_mount	*mp,
+	void			__user *arg)
+{
+	struct xfs_ag_geometry	ageo;
+	int			error;
+
+	if (copy_from_user(&ageo, arg, sizeof(ageo)))
+		return -EFAULT;
+
+	error = xfs_ag_get_geometry(mp, ageo.ag_number, &ageo);
+	if (error)
+		return error;
+
+	if (copy_to_user(arg, &ageo, sizeof(ageo)))
+		return -EFAULT;
+	return 0;
+}
+
 /*
  * Linux extended inode flags interface.
  */
@@ -1930,6 +1951,9 @@ xfs_file_ioctl(
 	case XFS_IOC_FSGEOMETRY:
 		return xfs_ioc_fsgeometry(mp, arg, 5);
 
+	case XFS_IOC_AG_GEOMETRY:
+		return xfs_ioc_ag_geometry(mp, arg);
+
 	case XFS_IOC_GETVERSION:
 		return put_user(inode->i_generation, (int __user *)arg);
 

fs/xfs/xfs_ioctl32.c

@@ -563,6 +563,7 @@ xfs_file_compat_ioctl(
 	case XFS_IOC_DIOINFO:
 	case XFS_IOC_FSGEOMETRY_V4:
 	case XFS_IOC_FSGEOMETRY:
+	case XFS_IOC_AG_GEOMETRY:
 	case XFS_IOC_FSGETXATTR:
 	case XFS_IOC_FSSETXATTR:
 	case XFS_IOC_FSGETXATTRA: