From: Darrick J. Wong <djwong@xxxxxxxxxx>
Dump refcount info from the kernel so we can prototype a sharing-aware
defrag/fs rearranging tool.
Signed-off-by: Darrick J. Wong <djwong@xxxxxxxxxx>
---
configure.ac | 1
include/builddefs.in | 4
io/Makefile | 5 +
io/fsrefcounts.c | 478 +++++++++++++++++++++++++++++++++++++++++++++++++
io/init.c | 1
io/io.h | 1
libfrog/fsrefcounts.h | 100 ++++++++++
m4/package_libcdev.m4 | 19 ++
man/man8/xfs_io.8 | 86 +++++++++
9 files changed, 695 insertions(+)
create mode 100644 io/fsrefcounts.c
create mode 100644 libfrog/fsrefcounts.h
diff --git a/configure.ac b/configure.ac
index f4f1563da8b..18e783a9180 100644
--- a/configure.ac
+++ b/configure.ac
@@ -188,6 +188,7 @@ AC_HAVE_MREMAP
AC_NEED_INTERNAL_FSXATTR
AC_NEED_INTERNAL_FSCRYPT_ADD_KEY_ARG
AC_HAVE_GETFSMAP
+AC_HAVE_GETFSREFCOUNTS
AC_HAVE_STATFS_FLAGS
AC_HAVE_MAP_SYNC
AC_HAVE_DEVMAPPER
diff --git a/include/builddefs.in b/include/builddefs.in
index 50ebb9f75d8..bf7d340ceb7 100644
--- a/include/builddefs.in
+++ b/include/builddefs.in
@@ -114,6 +114,7 @@ HAVE_MREMAP = @have_mremap@
NEED_INTERNAL_FSXATTR = @need_internal_fsxattr@
NEED_INTERNAL_FSCRYPT_ADD_KEY_ARG = @need_internal_fscrypt_add_key_arg@
HAVE_GETFSMAP = @have_getfsmap@
+HAVE_GETFSREFCOUNTS = @have_getfsrefcounts@
HAVE_STATFS_FLAGS = @have_statfs_flags@
HAVE_MAP_SYNC = @have_map_sync@
HAVE_DEVMAPPER = @have_devmapper@
@@ -165,6 +166,9 @@ endif
ifeq ($(HAVE_GETFSMAP),yes)
PCFLAGS+= -DHAVE_GETFSMAP
endif
+ifeq ($(HAVE_GETFSREFCOUNTS),yes)
+PCFLAGS+= -DHAVE_GETFSREFCOUNTS
+endif
ifeq ($(HAVE_FALLOCATE),yes)
PCFLAGS += -DHAVE_FALLOCATE
endif
diff --git a/io/Makefile b/io/Makefile
index 2b7748bfc13..c9e224c415a 100644
--- a/io/Makefile
+++ b/io/Makefile
@@ -116,6 +116,11 @@ ifeq ($(HAVE_FIEXCHANGE),yes)
LCFLAGS += -DHAVE_FIEXCHANGE
endif
+# On linux we get fsrefcounts from the system or define it ourselves
+# so include this unconditionally. If this reverts to only
+# the autoconf check w/o local definition, test HAVE_GETFSREFCOUNTS
+CFILES += fsrefcounts.c
+
default: depend $(LTCOMMAND)
include $(BUILDRULES)
diff --git a/io/fsrefcounts.c b/io/fsrefcounts.c
new file mode 100644
index 00000000000..930f8639fdc
--- /dev/null
+++ b/io/fsrefcounts.c
@@ -0,0 +1,478 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2022 Oracle. All Rights Reserved.
+ * Author: Darrick J. Wong <djwong@xxxxxxxxxx>
+ */
+#include "platform_defs.h"
+#include "command.h"
+#include "init.h"
+#include "libfrog/paths.h"
+#include "io.h"
+#include "input.h"
+#include "libfrog/fsgeom.h"
+#include "libfrog/fsrefcounts.h"
+
+static cmdinfo_t fsrefcounts_cmd;
+static dev_t xfs_data_dev;
+
+static void
+fsrefcounts_help(void)
+{
+ printf(_(
+"\n"
+" Prints extent owner counts for the filesystem hosting the current file"
+"\n"
+" fsrefcounts prints the number of owners of disk blocks used by the whole\n"
+" filesystem. When possible, owner and offset information will be included\n"
+" in the space report.\n"
+"\n"
+" By default, each line of the listing takes the following form:\n"
+" extent: major:minor [startblock..endblock]: owner startoffset..endoffset length\n"
+" All the file offsets and disk blocks are in units of 512-byte blocks.\n"
+" -d -- query only the data device (default).\n"
+" -l -- query only the log device.\n"
+" -r -- query only the realtime device.\n"
+" -n -- query n extents at a time.\n"
+" -o -- only print extents with at least this many owners (default 1).\n"
+" -O -- only print extents with no more than this many owners (default 2^64-1).\n"
+" -m -- output machine-readable format.\n"
+" -v -- Verbose information, show AG and offsets. Show flags legend on 2nd -v\n"
+"\n"
+"The optional start and end arguments require one of -d, -l, or -r to be set.\n"
+"\n"));
+}
+
+static void
+dump_refcounts(
+ unsigned long long *nr,
+ const unsigned long long min_owners,
+ const unsigned long long max_owners,
+ struct fsrefs_head *head)
+{
+ unsigned long long i;
+ struct fsrefs *p;
+
+ for (i = 0, p = head->fch_recs; i < head->fch_entries; i++, p++) {
+ if (p->fcr_owners < min_owners || p->fcr_owners > max_owners)
+ continue;
+ printf("\t%llu: %u:%u [%lld..%lld]: ", i + (*nr),
+ major(p->fcr_device), minor(p->fcr_device),
+ (long long)BTOBBT(p->fcr_physical),
+ (long long)BTOBBT(p->fcr_physical + p->fcr_length - 1));
+ printf(_("%llu %lld\n"),
+ (unsigned long long)p->fcr_owners,
+ (long long)BTOBBT(p->fcr_length));
+ }
+
+ (*nr) += head->fch_entries;
+}
+
+static void
+dump_refcounts_machine(
+ unsigned long long *nr,
+ const unsigned long long min_owners,
+ const unsigned long long max_owners,
+ struct fsrefs_head *head)
+{
+ unsigned long long i;
+ struct fsrefs *p;
+
+ if (*nr == 0)
+ printf(_("EXT,MAJOR,MINOR,PSTART,PEND,OWNERS,LENGTH\n"));
+ for (i = 0, p = head->fch_recs; i < head->fch_entries; i++, p++) {
+ if (p->fcr_owners < min_owners || p->fcr_owners > max_owners)
+ continue;
+ printf("%llu,%u,%u,%lld,%lld,", i + (*nr),
+ major(p->fcr_device), minor(p->fcr_device),
+ (long long)BTOBBT(p->fcr_physical),
+ (long long)BTOBBT(p->fcr_physical + p->fcr_length - 1));
+ printf("%llu,%lld\n",
+ (unsigned long long)p->fcr_owners,
+ (long long)BTOBBT(p->fcr_length));
+ }
+
+ (*nr) += head->fch_entries;
+}
+
+/*
+ * Verbose mode displays:
+ * extent: major:minor [startblock..endblock]: owners \
+ * ag# (agoffset..agendoffset) totalbbs flags
+ */
+#define MINRANGE_WIDTH 16
+#define MINAG_WIDTH 2
+#define MINTOT_WIDTH 5
+#define NFLG 4 /* count of flags */
+#define FLG_NULL 00000 /* Null flag */
+#define FLG_BSU 01000 /* Not on begin of stripe unit */
+#define FLG_ESU 00100 /* Not on end of stripe unit */
+#define FLG_BSW 00010 /* Not on begin of stripe width */
+#define FLG_ESW 00001 /* Not on end of stripe width */
+static void
+dump_refcounts_verbose(
+ unsigned long long *nr,
+ const unsigned long long min_owners,
+ const unsigned long long max_owners,
+ struct fsrefs_head *head,
+ bool *dumped_flags,
+ struct xfs_fsop_geom *fsgeo)
+{
+ unsigned long long i;
+ struct fsrefs *p;
+ int agno;
+ off64_t agoff, bperag;
+ int boff_w, aoff_w, tot_w, agno_w, own_w;
+ int nr_w, dev_w;
+ char bbuf[40], abuf[40], obuf[40];
+ char nbuf[40], dbuf[40], gbuf[40];
+ int sunit, swidth;
+ int flg = 0;
+
+ boff_w = aoff_w = own_w = MINRANGE_WIDTH;
+ dev_w = 3;
+ nr_w = 4;
+ tot_w = MINTOT_WIDTH;
+ bperag = (off64_t)fsgeo->agblocks *
+ (off64_t)fsgeo->blocksize;
+ sunit = (fsgeo->sunit * fsgeo->blocksize);
+ swidth = (fsgeo->swidth * fsgeo->blocksize);
+
+ /*
+ * Go through the extents and figure out the width
+ * needed for all columns.
+ */
+ for (i = 0, p = head->fch_recs; i < head->fch_entries; i++, p++) {
+ if (p->fcr_owners < min_owners || p->fcr_owners > max_owners)
+ continue;
+ if (sunit &&
+ (p->fcr_physical % sunit != 0 ||
+ ((p->fcr_physical + p->fcr_length) % sunit) != 0 ||
+ p->fcr_physical % swidth != 0 ||
+ ((p->fcr_physical + p->fcr_length) % swidth) != 0))
+ flg = 1;
+ if (flg)
+ *dumped_flags = true;
+ snprintf(nbuf, sizeof(nbuf), "%llu", (*nr) + i);
+ nr_w = max(nr_w, strlen(nbuf));
+ if (head->fch_oflags & FCH_OF_DEV_T)
+ snprintf(dbuf, sizeof(dbuf), "%u:%u",
+ major(p->fcr_device),
+ minor(p->fcr_device));
+ else
+ snprintf(dbuf, sizeof(dbuf), "0x%x", p->fcr_device);
+ dev_w = max(dev_w, strlen(dbuf));
+ snprintf(bbuf, sizeof(bbuf), "[%lld..%lld]:",
+ (long long)BTOBBT(p->fcr_physical),
+ (long long)BTOBBT(p->fcr_physical + p->fcr_length - 1));
+ boff_w = max(boff_w, strlen(bbuf));
+ snprintf(obuf, sizeof(obuf), "%llu",
+ (unsigned long long)p->fcr_owners);
+ own_w = max(own_w, strlen(obuf));
+ if (p->fcr_device == xfs_data_dev) {
+ agno = p->fcr_physical / bperag;
+ agoff = p->fcr_physical - (agno * bperag);
+ snprintf(abuf, sizeof(abuf),
+ "(%lld..%lld)",
+ (long long)BTOBBT(agoff),
+ (long long)BTOBBT(agoff + p->fcr_length - 1));
+ } else
+ abuf[0] = 0;
+ aoff_w = max(aoff_w, strlen(abuf));
+ tot_w = max(tot_w,
+ numlen(BTOBBT(p->fcr_length), 10));
+ }
+ agno_w = max(MINAG_WIDTH, numlen(fsgeo->agcount, 10));
+ if (*nr == 0)
+ printf("%*s: %-*s %-*s %-*s %*s %-*s %*s%s\n",
+ nr_w, _("EXT"),
+ dev_w, _("DEV"),
+ boff_w, _("BLOCK-RANGE"),
+ own_w, _("OWNERS"),
+ agno_w, _("AG"),
+ aoff_w, _("AG-OFFSET"),
+ tot_w, _("TOTAL"),
+ flg ? _(" FLAGS") : "");
+ for (i = 0, p = head->fch_recs; i < head->fch_entries; i++, p++) {
+ if (p->fcr_owners < min_owners || p->fcr_owners > max_owners)
+ continue;
+ flg = FLG_NULL;
+ /*
+ * If striping enabled, determine if extent starts/ends
+ * on a stripe unit boundary.
+ */
+ if (sunit) {
+ if (p->fcr_physical % sunit != 0)
+ flg |= FLG_BSU;
+ if (((p->fcr_physical +
+ p->fcr_length ) % sunit ) != 0)
+ flg |= FLG_ESU;
+ if (p->fcr_physical % swidth != 0)
+ flg |= FLG_BSW;
+ if (((p->fcr_physical +
+ p->fcr_length ) % swidth ) != 0)
+ flg |= FLG_ESW;
+ }
+ if (head->fch_oflags & FCH_OF_DEV_T)
+ snprintf(dbuf, sizeof(dbuf), "%u:%u",
+ major(p->fcr_device),
+ minor(p->fcr_device));
+ else
+ snprintf(dbuf, sizeof(dbuf), "0x%x", p->fcr_device);
+ snprintf(bbuf, sizeof(bbuf), "[%lld..%lld]:",
+ (long long)BTOBBT(p->fcr_physical),
+ (long long)BTOBBT(p->fcr_physical + p->fcr_length - 1));
+ snprintf(obuf, sizeof(obuf), "%llu",
+ (unsigned long long)p->fcr_owners);
+ if (p->fcr_device == xfs_data_dev) {
+ agno = p->fcr_physical / bperag;
+ agoff = p->fcr_physical - (agno * bperag);
+ snprintf(abuf, sizeof(abuf),
+ "(%lld..%lld)",
+ (long long)BTOBBT(agoff),
+ (long long)BTOBBT(agoff + p->fcr_length - 1));
+ snprintf(gbuf, sizeof(gbuf),
+ "%lld",
+ (long long)agno);
+ } else {
+ abuf[0] = 0;
+ gbuf[0] = 0;
+ }
+ printf("%*llu: %-*s %-*s %-*s %-*s %-*s %*lld",
+ nr_w, (*nr) + i, dev_w, dbuf, boff_w, bbuf, own_w,
+ obuf, agno_w, gbuf, aoff_w, abuf, tot_w,
+ (long long)BTOBBT(p->fcr_length));
+ if (flg == FLG_NULL)
+ printf("\n");
+ else
+ printf(" %-*.*o\n", NFLG, NFLG, flg);
+ }
+
+ (*nr) += head->fch_entries;
+}
+
+static void
+dump_verbose_key(void)
+{
+ printf(_(" FLAG Values:\n"));
+ printf(_(" %*.*o Doesn't begin on stripe unit\n"),
+ NFLG+1, NFLG+1, FLG_BSU);
+ printf(_(" %*.*o Doesn't end on stripe unit\n"),
+ NFLG+1, NFLG+1, FLG_ESU);
+ printf(_(" %*.*o Doesn't begin on stripe width\n"),
+ NFLG+1, NFLG+1, FLG_BSW);
+ printf(_(" %*.*o Doesn't end on stripe width\n"),
+ NFLG+1, NFLG+1, FLG_ESW);
+}
+
+static int
+fsrefcounts_f(
+ int argc,
+ char **argv)
+{
+ struct fsrefs *p;
+ struct fsrefs_head *head;
+ struct fsrefs *l, *h;
+ struct xfs_fsop_geom fsgeo;
+ long long start = 0;
+ long long end = -1;
+ unsigned long long min_owners = 1;
+ unsigned long long max_owners = ULLONG_MAX;
+ int map_size;
+ int nflag = 0;
+ int vflag = 0;
+ int mflag = 0;
+ int i = 0;
+ int c;
+ unsigned long long nr = 0;
+ size_t fsblocksize, fssectsize;
+ struct fs_path *fs;
+ static bool tab_init;
+ bool dumped_flags = false;
+ int dflag, lflag, rflag;
+
+ init_cvtnum(&fsblocksize, &fssectsize);
+
+ dflag = lflag = rflag = 0;
+ while ((c = getopt(argc, argv, "dlmn:o:O:rv")) != EOF) {
+ switch (c) {
+ case 'd': /* data device */
+ dflag = 1;
+ break;
+ case 'l': /* log device */
+ lflag = 1;
+ break;
+ case 'm': /* machine readable format */
+ mflag++;
+ break;
+ case 'n': /* number of extents specified */
+ nflag = cvt_u32(optarg, 10);
+ if (errno)
+ return command_usage(&fsrefcounts_cmd);
+ break;
+ case 'o': /* minimum owners */
+ min_owners = cvt_u64(optarg, 10);
+ if (errno)
+ return command_usage(&fsrefcounts_cmd);
+ if (min_owners < 1) {
+ fprintf(stderr,
+ _("min_owners must be greater than zero.\n"));
+ exitcode = 1;
+ return 0;
+ }
+ break;
+ case 'O': /* maximum owners */
+ max_owners = cvt_u64(optarg, 10);
+ if (errno)
+ return command_usage(&fsrefcounts_cmd);
+ if (max_owners < 1) {
+ fprintf(stderr,
+ _("max_owners must be greater than zero.\n"));
+ exitcode = 1;
+ return 0;
+ }
+ break;
+ case 'r': /* rt device */
+ rflag = 1;
+ break;
+ case 'v': /* Verbose output */
+ vflag++;
+ break;
+ default:
+ exitcode = 1;
+ return command_usage(&fsrefcounts_cmd);
+ }
+ }
+
+ if ((dflag + lflag + rflag > 1) || (mflag > 0 && vflag > 0) ||
+ (argc > optind && dflag + lflag + rflag == 0)) {
+ exitcode = 1;
+ return command_usage(&fsrefcounts_cmd);
+ }
+
+ if (argc > optind) {
+ start = cvtnum(fsblocksize, fssectsize, argv[optind]);
+ if (start < 0) {
+ fprintf(stderr,
+ _("Bad refcount start_bblock %s.\n"),
+ argv[optind]);
+ exitcode = 1;
+ return 0;
+ }
+ start <<= BBSHIFT;
+ }
+
+ if (argc > optind + 1) {
+ end = cvtnum(fsblocksize, fssectsize, argv[optind + 1]);
+ if (end < 0) {
+ fprintf(stderr,
+ _("Bad refcount end_bblock %s.\n"),
+ argv[optind + 1]);
+ exitcode = 1;
+ return 0;
+ }
+ end <<= BBSHIFT;
+ }
+
+ if (vflag) {
+ c = -xfrog_geometry(file->fd, &fsgeo);
+ if (c) {
+ fprintf(stderr,
+ _("%s: can't get geometry [\"%s\"]: %s\n"),
+ progname, file->name, strerror(c));
+ exitcode = 1;
+ return 0;
+ }
+ }
+
+ map_size = nflag ? nflag : 131072 / sizeof(struct fsrefs);
+ head = malloc(fsrefs_sizeof(map_size));
+ if (head == NULL) {
+ fprintf(stderr, _("%s: malloc of %llu bytes failed.\n"),
+ progname,
+ (unsigned long long)fsrefs_sizeof(map_size));
+ exitcode = 1;
+ return 0;
+ }
+
+ memset(head, 0, sizeof(*head));
+ l = head->fch_keys;
+ h = head->fch_keys + 1;
+ if (dflag) {
+ l->fcr_device = h->fcr_device = file->fs_path.fs_datadev;
+ } else if (lflag) {
+ l->fcr_device = h->fcr_device = file->fs_path.fs_logdev;
+ } else if (rflag) {
+ l->fcr_device = h->fcr_device = file->fs_path.fs_rtdev;
+ } else {
+ l->fcr_device = 0;
+ h->fcr_device = UINT_MAX;
+ }
+ l->fcr_physical = start;
+ h->fcr_physical = end;
+ h->fcr_owners = ULLONG_MAX;
+ h->fcr_flags = UINT_MAX;
+
+ /*
+ * If this is an XFS filesystem, remember the data device.
+ * (We report AG number/block for data device extents on XFS).
+ */
+ if (!tab_init) {
+ fs_table_initialise(0, NULL, 0, NULL);
+ tab_init = true;
+ }
+ fs = fs_table_lookup(file->name, FS_MOUNT_POINT);
+ xfs_data_dev = fs ? fs->fs_datadev : 0;
+
+ head->fch_count = map_size;
+ do {
+ /* Get some extents */
+ i = ioctl(file->fd, FS_IOC_GETFSREFCOUNTS, head);
+ if (i < 0) {
+ fprintf(stderr, _("%s: xfsctl(XFS_IOC_GETFSREFCOUNTS)"
+ " iflags=0x%x [\"%s\"]: %s\n"),
+ progname, head->fch_iflags, file->name,
+ strerror(errno));
+ free(head);
+ exitcode = 1;
+ return 0;
+ }
+
+ if (head->fch_entries == 0)
+ break;
+
+ if (vflag)
+ dump_refcounts_verbose(&nr, min_owners, max_owners,
+ head, &dumped_flags, &fsgeo);
+ else if (mflag)
+ dump_refcounts_machine(&nr, min_owners, max_owners,
+ head);
+ else
+ dump_refcounts(&nr, min_owners, max_owners, head);
+
+ p = &head->fch_recs[head->fch_entries - 1];
+ if (p->fcr_flags & FCR_OF_LAST)
+ break;
+ fsrefs_advance(head);
+ } while (true);
+
+ if (dumped_flags)
+ dump_verbose_key();
+
+ free(head);
+ return 0;
+}
+
+void
+fsrefcounts_init(void)
+{
+ fsrefcounts_cmd.name = "fsrefcounts";
+ fsrefcounts_cmd.cfunc = fsrefcounts_f;
+ fsrefcounts_cmd.argmin = 0;
+ fsrefcounts_cmd.argmax = -1;
+ fsrefcounts_cmd.flags = CMD_NOMAP_OK | CMD_FLAG_FOREIGN_OK;
+ fsrefcounts_cmd.args = _("[-d|-l|-r] [-m|-v] [-n nx] [start] [end]");
+ fsrefcounts_cmd.oneline = _("print filesystem owner counts for a range of blocks");
+ fsrefcounts_cmd.help = fsrefcounts_help;
+
+ add_command(&fsrefcounts_cmd);
+}
diff --git a/io/init.c b/io/init.c
index 78d7d04e7a6..771091412d0 100644
--- a/io/init.c
+++ b/io/init.c
@@ -58,6 +58,7 @@ init_commands(void)
flink_init();
freeze_init();
fsmap_init();
+ fsrefcounts_init();
fsync_init();
getrusage_init();
help_init();
diff --git a/io/io.h b/io/io.h
index 77bedf5159d..de4ef6077f2 100644
--- a/io/io.h
+++ b/io/io.h
@@ -190,3 +190,4 @@ extern void crc32cselftest_init(void);
extern void bulkstat_init(void);
extern void atomicupdate_init(void);
extern void aginfo_init(void);
+extern void fsrefcounts_init(void);
diff --git a/libfrog/fsrefcounts.h b/libfrog/fsrefcounts.h
new file mode 100644
index 00000000000..b9057b90ff9
--- /dev/null
+++ b/libfrog/fsrefcounts.h
@@ -0,0 +1,100 @@
+#ifdef HAVE_GETFSREFCOUNTS
+# include <linux/fsrefcounts.h>
+#endif
+
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/*
+ * FS_IOC_GETFSREFCOUNTS ioctl infrastructure.
+ *
+ * Copyright (C) 2022 Oracle. All Rights Reserved.
+ *
+ * Author: Darrick J. Wong <djwong@xxxxxxxxxx>
+ */
+#ifndef _LINUX_FSREFCOUNTS_H
+#define _LINUX_FSREFCOUNTS_H
+
+#include <linux/types.h>
+
+/*
+ * Structure for FS_IOC_GETFSREFCOUNTS.
+ *
+ * The memory layout for this call are the scalar values defined in
+ * struct fsrefs_head, followed by two struct fsrefs that describe the
+ * lower and upper bound of mappings to return, followed by an array of
+ * struct fsrefs mappings.
+ *
+ * fch_iflags control the output of the call, whereas fch_oflags report
+ * on the overall record output. fch_count should be set to the length
+ * of the fch_recs array, and fch_entries will be set to the number of
+ * entries filled out during each call. If fch_count is zero, the number
+ * of refcount mappings will be returned in fch_entries, though no
+ * mappings will be returned. fch_reserved must be set to zero.
+ *
+ * The two elements in the fch_keys array are used to constrain the
+ * output. The first element in the array should represent the lowest
+ * disk mapping ("low key") that the user wants to learn about. If this
+ * value is all zeroes, the filesystem will return the first entry it
+ * knows about. For a subsequent call, the contents of
+ * fsrefs_head.fch_recs[fsrefs_head.fch_count - 1] should be copied into
+ * fch_keys[0] to have the kernel start where it left off.
+ *
+ * The second element in the fch_keys array should represent the highest
+ * disk mapping ("high key") that the user wants to learn about. If this
+ * value is all ones, the filesystem will not stop until it runs out of
+ * mapping to return or runs out of space in fch_recs.
+ *
+ * fcr_device can be either a 32-bit cookie representing a device, or a
+ * 32-bit dev_t if the FCH_OF_DEV_T flag is set. fcr_physical and
+ * fcr_length are expressed in units of bytes. fcr_owners is the number
+ * of owners.
+ */
+struct fsrefs {
+ __u32 fcr_device; /* device id */
+ __u32 fcr_flags; /* mapping flags */
+ __u64 fcr_physical; /* device offset of segment */
+ __u64 fcr_owners; /* number of owners */
+ __u64 fcr_length; /* length of segment */
+ __u64 fcr_reserved[4]; /* must be zero */
+};
+
+struct fsrefs_head {
+ __u32 fch_iflags; /* control flags */
+ __u32 fch_oflags; /* output flags */
+ __u32 fch_count; /* # of entries in array incl. input */
+ __u32 fch_entries; /* # of entries filled in (output). */
+ __u64 fch_reserved[6]; /* must be zero */
+
+ struct fsrefs fch_keys[2]; /* low and high keys for the mapping search */
+ struct fsrefs fch_recs[]; /* returned records */
+};
+
+/* Size of an fsrefs_head with room for nr records. */
+static inline unsigned long long
+fsrefs_sizeof(
+ unsigned int nr)
+{
+ return sizeof(struct fsrefs_head) + nr * sizeof(struct fsrefs);
+}
+
+/* Start the next fsrefs query at the end of the current query results. */
+static inline void
+fsrefs_advance(
+ struct fsrefs_head *head)
+{
+ head->fch_keys[0] = head->fch_recs[head->fch_entries - 1];
+}
+
+/* fch_iflags values - set by FS_IOC_GETFSREFCOUNTS caller in the header. */
+/* no flags defined yet */
+#define FCH_IF_VALID 0
+
+/* fch_oflags values - returned in the header segment only. */
+#define FCH_OF_DEV_T 0x1 /* fcr_device values will be dev_t */
+
+/* fcr_flags values - returned for each non-header segment */
+#define FCR_OF_LAST (1U << 0) /* segment is the last in the dataset */
+
+/* XXX stealing XFS_IOC_GETBIOSIZE */
+#define FS_IOC_GETFSREFCOUNTS _IOWR('X', 47, struct fsrefs_head)
+
+#endif /* _LINUX_FSREFCOUNTS_H */
diff --git a/m4/package_libcdev.m4 b/m4/package_libcdev.m4
index 062730a1f06..5293dd1aec2 100644
--- a/m4/package_libcdev.m4
+++ b/m4/package_libcdev.m4
@@ -347,6 +347,25 @@ struct fsmap_head fh;
AC_SUBST(have_getfsmap)
])
+#
+# Check if we have a FS_IOC_GETFSREFCOUNTS ioctl (Linux)
+#
+AC_DEFUN([AC_HAVE_GETFSREFCOUNTS],
+ [ AC_MSG_CHECKING([for GETFSREFCOUNTS])
+ AC_LINK_IFELSE([AC_LANG_PROGRAM([[
+#define _GNU_SOURCE
+#include <sys/syscall.h>
+#include <unistd.h>
+#include <linux/fs.h>
+#include <linux/fsrefcounts.h>
+ ]], [[
+ unsigned long x = FS_IOC_GETFSREFCOUNTS;
+ struct fsrefs_head fh;
+ ]])],[have_getfsrefcounts=yes
+ AC_MSG_RESULT(yes)],[AC_MSG_RESULT(no)])
+ AC_SUBST(have_getfsrefcounts)
+ ])
+
AC_DEFUN([AC_HAVE_STATFS_FLAGS],
[
AC_CHECK_TYPE(struct statfs,
diff --git a/man/man8/xfs_io.8 b/man/man8/xfs_io.8
index df56080b8b8..ece778fc76c 100644
--- a/man/man8/xfs_io.8
+++ b/man/man8/xfs_io.8
@@ -1593,6 +1593,92 @@ flag.
.RE
.PD
.TP
+.BI "fsrefcounts [ \-d | \-l | \-r ] [ \-m | \-v ] [ \-n " nx " ] [ \-o " min_owners " ] [ \-O " max_owners " ] [ " start " ] [ " end " ]
+Prints the number of owners of disk extents used by the filesystem hosting the
+current file.
+The listing does not include free blocks.
+Each line of the listings takes the following form:
+.PP
+.RS
+.IR extent ": " major ":" minor " [" startblock .. endblock "]: " owners " " length
+.PP
+All blocks, offsets, and lengths are specified in units of 512-byte
+blocks, no matter what the filesystem's block size is.
+The optional
+.I start
+and
+.I end
+arguments can be used to constrain the output to a particular range of
+disk blocks.
+If these two options are specified, exactly one of
+.BR "-d" ", " "-l" ", or " "-r"
+must also be set.
+.RE
+.RS 1.0i
+.PD 0
+.TP
+.BI \-d
+Display only extents from the data device.
+This option only applies for XFS filesystems.
+.TP
+.BI \-l
+Display only extents from the external log device.
+This option only applies to XFS filesystems.
+.TP
+.BI \-r
+Display only extents from the realtime device.
+This option only applies to XFS filesystems.
+.TP
+.BI \-m
+Display results in a machine readable format (CSV).
+This option is not compatible with the
+.B \-v
+flag.
+The columns of the output are: extent number, device major, device minor,
+physical start, physical end, number of owners, length.
+The start, end, and length numbers are provided in units of 512b.
+
+.TP
+.BI \-n " num_extents"
+If this option is given,
+.B fsrefcounts
+obtains the extent list of the file in groups of
+.I num_extents
+extents.
+In the absence of
+.BR "-n" ", " "fsrefcounts"
+queries the system for extents in groups of 131,072 records.
+.TP
+.BI \-o " min_owners"
+Only print extents having at least this many owners.
+This argument must be in the range 1 to 2^64-1.
+The default value is 1.
+.TP
+.BI \-O " max_owners"
+Only print extents having this many or fewer owners.
+This argument must be in the range 1 to 2^64-1.
+There is no limit by default.
+.TP
+.B \-v
+Shows verbose information.
+When this flag is specified, additional AG specific information is
+appended to each line in the following form:
+.IP
+.RS 1.2i
+.IR agno " (" startagblock .. endagblock ") " nblocks " " flags
+.RE
+.IP
+A second
+.B \-v
+option will print out the
+.I flags
+legend.
+This option is not compatible with the
+.B \-m
+flag.
+.RE
+.PD
+.TP
.BI "aginfo [ \-a " agno " ] [ \-o " nr " ]"
Show information about or update the state of allocation groups.
.RE
