lsblk: add --dedup <column>

The target use-case are systems with large number of multi-path
devices or systems with duplicate (copied) filesystems.

The feature is flexible enough to use arbitrary column (for example
WWM or UUID, ...) as de-duplication key.

For example tree with multi-path devices sd{c,d,e,f}

./lsblk
NAME        MAJ:MIN RM   SIZE RO TYPE  MOUNTPOINT
sda           8:0    0 223.6G  0 disk
├─sda1        8:1    0   200M  0 part  /boot/efi
├─sda2        8:2    0   200M  0 part  /boot
├─sda3        8:3    0 130.3G  0 part
├─sda4        8:4    0    50G  0 part  /
└─sda5        8:5    0  42.9G  0 part
sdb           8:16   0  74.5G  0 disk
└─sdb1        8:17   0  74.5G  0 part  /home/archive
sdc           8:32   0   100M  0 disk
└─mpatha    253:0    0   100M  0 mpath
  ├─mpatha1 253:1    0    50M  0 part
  └─mpatha2 253:2    0    49M  0 part
sdd           8:48   0   100M  0 disk
└─mpatha    253:0    0   100M  0 mpath
  ├─mpatha1 253:1    0    50M  0 part
  └─mpatha2 253:2    0    49M  0 part
sde           8:64   0   100M  0 disk
└─mpatha    253:0    0   100M  0 mpath
  ├─mpatha1 253:1    0    50M  0 part
  └─mpatha2 253:2    0    49M  0 part
sdf           8:80   0   100M  0 disk
└─mpatha    253:0    0   100M  0 mpath
  ├─mpatha1 253:1    0    50M  0 part
  └─mpatha2 253:2    0    49M  0 part

De-duplicate by WWN:

./lsblk -M WWN
NAME        MAJ:MIN RM   SIZE RO TYPE  MOUNTPOINT
sda           8:0    0 223.6G  0 disk
├─sda1        8:1    0   200M  0 part  /boot/efi
├─sda2        8:2    0   200M  0 part  /boot
├─sda3        8:3    0 130.3G  0 part
├─sda4        8:4    0    50G  0 part  /
└─sda5        8:5    0  42.9G  0 part
sdb           8:16   0  74.5G  0 disk
└─sdb1        8:17   0  74.5G  0 part  /home/archive
sdc           8:32   0   100M  0 disk
└─mpatha    253:0    0   100M  0 mpath
  ├─mpatha1 253:1    0    50M  0 part
  └─mpatha2 253:2    0    49M  0 part

Addresses: https://github.com/karelzak/util-linux/issues/616
Signed-off-by: Karel Zak <kzak@redhat.com>

1 files changed, 64 insertions, 2 deletions

diff --git a/misc-utils/lsblk.c b/misc-utils/lsblk.c
index 35926a17d..95c3cdc4d 100644
--- a/misc-utils/lsblk.c
+++ b/misc-utils/lsblk.c
@@ -1641,6 +1641,43 @@ static int cmp_u64_cells(struct libscols_cell *a,
 	return *adata == *bdata ? 0 : *adata >= *bdata ? 1 : -1;
 }
 
+static void device_set_dedupkey(
+			struct lsblk_device *dev,
+			struct lsblk_device *parent,
+			int id)
+{
+	struct lsblk_iter itr;
+	struct lsblk_device *child = NULL;
+
+	dev->dedupkey = device_get_data(dev, parent, id, NULL);
+	if (dev->dedupkey)
+		DBG(DEV, ul_debugobj(dev, "%s: de-duplication key: %s", dev->name, dev->dedupkey));
+
+	if (dev->npartitions == 0)
+		/* For partitions we often read from parental whole-disk sysfs,
+		 * otherwise we can close */
+		ul_path_close_dirfd(dev->sysfs);
+
+	lsblk_reset_iter(&itr, LSBLK_ITER_FORWARD);
+
+	while (lsblk_device_next_child(dev, &itr, &child) == 0)
+		device_set_dedupkey(child, dev, id);
+
+	/* Let's be careful with number of open files */
+	ul_path_close_dirfd(dev->sysfs);
+}
+
+static void devtree_set_dedupkeys(struct lsblk_devtree *tr, int id)
+{
+	struct lsblk_iter itr;
+	struct lsblk_device *dev = NULL;
+
+	lsblk_reset_iter(&itr, LSBLK_ITER_FORWARD);
+
+	while (lsblk_devtree_next_root(tr, &itr, &dev) == 0)
+		device_set_dedupkey(dev, NULL, id);
+}
+
 static void __attribute__((__noreturn__)) usage(void)
 {
 	FILE *out = stdout;
@@ -1665,6 +1702,7 @@ static void __attribute__((__noreturn__)) usage(void)
 	fputs(_(" -J, --json           use JSON output format\n"), out);
 	fputs(_(" -l, --list           use list format output\n"), out);
 	fputs(_(" -T, --tree           use tree format output\n"), out);
+	fputs(_(" -M, --dedup <column> de-duplicate output by <column>\n"), out);
 	fputs(_(" -m, --perms          output info about permissions\n"), out);
 	fputs(_(" -n, --noheadings     don't print headings\n"), out);
 	fputs(_(" -o, --output <list>  output columns\n"), out);
@@ -1699,7 +1737,11 @@ static void check_sysdevblock(void)
 
 int main(int argc, char *argv[])
 {
-	struct lsblk _ls = { .sort_id = -1, .flags = LSBLK_TREE };
+	struct lsblk _ls = {
+		.sort_id = -1,
+		.dedup_id = -1,
+		.flags = LSBLK_TREE
+	};
 	struct lsblk_devtree *tr = NULL;
 	int c, status = EXIT_FAILURE;
 	char *outarg = NULL;
@@ -1715,6 +1757,7 @@ int main(int argc, char *argv[])
 		{ "bytes",      no_argument,       NULL, 'b' },
 		{ "nodeps",     no_argument,       NULL, 'd' },
 		{ "discard",    no_argument,       NULL, 'D' },
+		{ "dedup",      required_argument, NULL, 'M' },
 		{ "zoned",      no_argument,       NULL, 'z' },
 		{ "help",	no_argument,       NULL, 'h' },
 		{ "json",       no_argument,       NULL, 'J' },
@@ -1763,7 +1806,7 @@ int main(int argc, char *argv[])
 	lsblk_init_debug();
 
 	while((c = getopt_long(argc, argv,
-			       "abdDze:fhJlnmo:OpPiI:rstVSTx:", longopts, NULL)) != -1) {
+			       "abdDze:fhJlnmM:o:OpPiI:rstVSTx:", longopts, NULL)) != -1) {
 
 		err_exclusive_options(c, longopts, excl, excl_st);
 
@@ -1880,6 +1923,12 @@ int main(int argc, char *argv[])
 		case 'V':
 			printf(UTIL_LINUX_VERSION);
 			return EXIT_SUCCESS;
+		case 'M':
+			lsblk->dedup_id = column_name_to_id(optarg, strlen(optarg));
+			if (lsblk->dedup_id >= 0)
+				break;
+			errtryhelp(EXIT_FAILURE);
+			break;
 		case 'x':
 			lsblk->flags &= ~LSBLK_TREE; /* disable the default */
 			lsblk->sort_id = column_name_to_id(optarg, strlen(optarg));
@@ -1928,6 +1977,12 @@ int main(int argc, char *argv[])
 		lsblk->sort_hidden = 1;
 	}
 
+	if (lsblk->dedup_id >= 0 && column_id_to_number(lsblk->dedup_id) < 0) {
+		/* the deduplication column is not between output columns -- add as hidden */
+		add_column(lsblk->dedup_id);
+		lsblk->dedup_hidden = 1;
+	}
+
 	lsblk_mnt_init();
 	scols_init_debug(0);
 	ul_path_init_debug();
@@ -1955,6 +2010,8 @@ int main(int argc, char *argv[])
 			fl &= ~SCOLS_FL_TREE;
 		if (lsblk->sort_hidden && lsblk->sort_id == id)
 			fl |= SCOLS_FL_HIDDEN;
+		if (lsblk->dedup_hidden && lsblk->dedup_id == id)
+			fl |= SCOLS_FL_HIDDEN;
 
 		cl = scols_table_new_column(lsblk->table, ci->name, ci->whint, fl);
 		if (!cl) {
@@ -2012,6 +2069,11 @@ int main(int argc, char *argv[])
 					  EXIT_SUCCESS;		/* all success */
 	}
 
+	if (lsblk->dedup_id > -1) {
+		devtree_set_dedupkeys(tr, lsblk->dedup_id);
+		lsblk_devtree_deduplicate_devices(tr);
+	}
+
 	devtree_to_scols(tr, lsblk->table);
 
 	if (lsblk->sort_col)