[PATCH 5/8] xfs_db: dump per-AG reservations

["Darrick J. Wong" <darrick.wong@oracle.com>]

From: Darrick J. Wong <darrick.wong@oracle.com>

Add a new 'agresv' command to print the size and free blocks count of an
AG along with the size and usage of the per-AG reservation.  This
command can be used to aid in diagnosing why a particular filesystem
fails the mount time per-AG space reservation, and to figure out how
much space needs to be freed from a given AG to fix the problem.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
 db/info.c                |  104 ++++++++++++++++++++++++++++++++++++++++++++++
 libxfs/libxfs_api_defs.h |    5 ++
 man/man8/xfs_db.8        |    5 ++
 3 files changed, 114 insertions(+)


diff --git a/db/info.c b/db/info.c
index e5f1c2dd..fc5ccfe7 100644
--- a/db/info.c
+++ b/db/info.c
@@ -8,6 +8,7 @@
 #include "init.h"
 #include "output.h"
 #include "libfrog/fsgeom.h"
+#include "libfrog/logging.h"
 
 static void
 info_help(void)
@@ -45,8 +46,111 @@ static const struct cmdinfo info_cmd = {
 	.help =		info_help,
 };
 
+static void
+agresv_help(void)
+{
+	dbprintf(_(
+"\n"
+" Print the size and per-AG reservation information some allocation groups.\n"
+"\n"
+" Specific allocation group numbers can be provided as command line arguments.\n"
+" If no arguments are provided, all allocation groups are iterated.\n"
+"\n"
+));
+
+}
+
+static void
+print_agresv_info(
+	xfs_agnumber_t	agno)
+{
+	struct xfs_buf	*bp;
+	struct xfs_agf	*agf;
+	xfs_extlen_t	ask = 0;
+	xfs_extlen_t	used = 0;
+	xfs_extlen_t	free = 0;
+	xfs_extlen_t	length = 0;
+	int		error;
+
+	error = -libxfs_refcountbt_calc_reserves(mp, NULL, agno, &ask, &used);
+	if (error)
+		xfrog_perror(error, "refcountbt");
+	error = -libxfs_finobt_calc_reserves(mp, NULL, agno, &ask, &used);
+	if (error)
+		xfrog_perror(error, "finobt");
+	error = -libxfs_rmapbt_calc_reserves(mp, NULL, agno, &ask, &used);
+	if (error)
+		xfrog_perror(error, "rmapbt");
+
+	error = -libxfs_read_agf(mp, NULL, agno, 0, &bp);
+	if (error)
+		xfrog_perror(error, "AGF");
+	agf = XFS_BUF_TO_AGF(bp);
+	length = be32_to_cpu(agf->agf_length);
+	free = be32_to_cpu(agf->agf_freeblks) +
+	       be32_to_cpu(agf->agf_flcount);
+	libxfs_putbuf(bp);
+
+	printf("AG %d: length: %u free: %u reserved: %u used: %u",
+			agno, length, free, ask, used);
+	if (ask - used > free)
+		printf(" <not enough space>");
+	printf("\n");
+}
+
+static int
+agresv_f(
+	int			argc,
+	char			**argv)
+{
+	xfs_agnumber_t		agno;
+	int			i;
+
+	if (argc > 1) {
+		for (i = 1; i < argc; i++) {
+			long	a;
+			char	*p;
+
+			errno = 0;
+			a = strtol(argv[i], &p, 0);
+			if (p == argv[i])
+				errno = ERANGE;
+			if (errno) {
+				perror(argv[i]);
+				continue;
+			}
+
+			if (a < 0 || a >= mp->m_sb.sb_agcount) {
+				fprintf(stderr, "%ld: Not a AG.\n", a);
+				continue;
+			}
+
+			print_agresv_info(a);
+		}
+		return 0;
+	}
+
+	for (agno = 0; agno < mp->m_sb.sb_agcount; agno++)
+		print_agresv_info(agno);
+
+	return 0;
+}
+
+static const struct cmdinfo agresv_cmd = {
+	.name =		"agresv",
+	.altname =	NULL,
+	.cfunc =	agresv_f,
+	.argmin =	0,
+	.argmax =	-1,
+	.canpush =	0,
+	.args =		NULL,
+	.oneline =	N_("print AG reservation stats"),
+	.help =		agresv_help,
+};
+
 void
 info_init(void)
 {
 	add_command(&info_cmd);
+	add_command(&agresv_cmd);
 }
diff --git a/libxfs/libxfs_api_defs.h b/libxfs/libxfs_api_defs.h
index eed63ace..cc7304ad 100644
--- a/libxfs/libxfs_api_defs.h
+++ b/libxfs/libxfs_api_defs.h
@@ -173,4 +173,9 @@
 #define xfs_ag_init_headers		libxfs_ag_init_headers
 #define xfs_buf_delwri_submit		libxfs_buf_delwri_submit
 
+#define xfs_refcountbt_calc_reserves	libxfs_refcountbt_calc_reserves
+#define xfs_finobt_calc_reserves	libxfs_finobt_calc_reserves
+#define xfs_rmapbt_calc_reserves	libxfs_rmapbt_calc_reserves
+#define xfs_read_agf			libxfs_read_agf
+
 #endif /* __LIBXFS_API_DEFS_H__ */
diff --git a/man/man8/xfs_db.8 b/man/man8/xfs_db.8
index 9f1ff761..7f73d458 100644
--- a/man/man8/xfs_db.8
+++ b/man/man8/xfs_db.8
@@ -179,6 +179,11 @@ Set current address to the AGI block for allocation group
 .IR agno .
 If no argument is given, use the current allocation group.
 .TP
+.BI "agresv [" agno ]
+Displays the length, free block count, per-AG reservation size, and per-AG
+reservation usage for a given AG.
+If no argument is given, display information for all AGs.
+.TP
 .BI "attr_remove [\-r|\-u|\-s] [\-n] " name
 Remove the specified extended attribute from the current file.
 .RS 1.0i