losetup: add MAJ a MIN for device and backing-file

Addresses: https://github.com/util-linux/util-linux/issues/2460
Signed-off-by: Karel Zak <kzak@redhat.com>

diff --git a/sys-utils/losetup.c b/sys-utils/losetup.c
index e17b4a3e458b805fc5420f702008c3756ccc2703..507292bd80570ee3c4acbffdd893ba86087331ed 100644 (file)
--- a/sys-utils/losetup.c
+++ b/sys-utils/losetup.c
@@ -45,7 +45,11 @@ enum {
        COL_BACK_FILE,
        COL_BACK_INO,
        COL_BACK_MAJMIN,
+       COL_BACK_MAJ,
+       COL_BACK_MIN,
        COL_MAJMIN,
+       COL_MAJ,
+       COL_MIN,
        COL_OFFSET,
        COL_PARTSCAN,
        COL_REF,
@@ -74,6 +78,8 @@ static const struct colinfo infos[] = {
        [COL_BACK_FILE]   = { "BACK-FILE",  0.3, SCOLS_FL_NOEXTREMES, N_("device backing file")},
        [COL_BACK_INO]    = { "BACK-INO",     4, SCOLS_FL_RIGHT, N_("backing file inode number"), SCOLS_JSON_NUMBER},
        [COL_BACK_MAJMIN] = { "BACK-MAJ:MIN", 6, 0, N_("backing file major:minor device number")},
+       [COL_BACK_MAJ]    = { "BACK-MAJ",     6, 0, N_("backing file major device number")},
+       [COL_BACK_MIN]    = { "BACK-MIN",     6, 0, N_("backing file minor device number")},
        [COL_NAME]        = { "NAME",      0.25, 0, N_("loop device name")},
        [COL_OFFSET]      = { "OFFSET",       5, SCOLS_FL_RIGHT, N_("offset from the beginning"), SCOLS_JSON_NUMBER},
        [COL_PARTSCAN]    = { "PARTSCAN",     1, SCOLS_FL_RIGHT, N_("partscan flag set"), SCOLS_JSON_BOOLEAN},
@@ -81,6 +87,8 @@ static const struct colinfo infos[] = {
        [COL_RO]          = { "RO",           1, SCOLS_FL_RIGHT, N_("read-only device"), SCOLS_JSON_BOOLEAN},
        [COL_SIZELIMIT]   = { "SIZELIMIT",    5, SCOLS_FL_RIGHT, N_("size limit of the file in bytes"), SCOLS_JSON_NUMBER},
        [COL_MAJMIN]      = { "MAJ:MIN",      3, 0, N_("loop device major:minor number")},
+       [COL_MAJ]         = { "MAJ",          1, SCOLS_FL_RIGHT, N_("loop device major number"), SCOLS_JSON_NUMBER},
+       [COL_MIN]         = { "MIN",          1, SCOLS_FL_RIGHT, N_("loop device minor number"), SCOLS_JSON_NUMBER},
        [COL_DIO]         = { "DIO",          1, SCOLS_FL_RIGHT, N_("access backing file with direct-io"), SCOLS_JSON_BOOLEAN},
        [COL_LOGSEC]      = { "LOG-SEC",      4, SCOLS_FL_RIGHT, N_("logical sector size in bytes"), SCOLS_JSON_NUMBER},
 };
@@ -226,9 +234,24 @@ static int delete_all_loops(struct loopdev_cxt *lc)
        return res;
 }
 
+static dev_t get_device_devno(struct loopdev_cxt *lc, struct stat *st)
+{
+       if (st->st_rdev)
+               return st->st_rdev;
+
+       if (loopcxt_get_device(lc)
+           && stat(loopcxt_get_device(lc), st) == 0
+           && S_ISBLK(st->st_mode)
+           && major(st->st_rdev) == LOOPDEV_MAJOR)
+               return st->st_rdev;
+
+       return 0;
+}
+
 static int set_scols_data(struct loopdev_cxt *lc, struct libscols_line *ln)
 {
        size_t i;
+       struct stat st = { .st_rdev = 0 };
 
        for (i = 0; i < ncolumns; i++) {
                const char *p = NULL;                   /* external data */
@@ -259,16 +282,38 @@ static int set_scols_data(struct loopdev_cxt *lc, struct libscols_line *ln)
                                                major(dev), minor(dev));
                        break;
                }
+               case COL_BACK_MAJ:
+               {
+                       dev_t dev = 0;
+                       if (loopcxt_get_backing_devno(lc, &dev) == 0 && dev)
+                               xasprintf(&np, "%u", major(dev));
+                       break;
+               }
+               case COL_BACK_MIN:
+               {
+                       dev_t dev = 0;
+                       if (loopcxt_get_backing_devno(lc, &dev) == 0 && dev)
+                               xasprintf(&np, "%u", minor(dev));
+                       break;
+               }
                case COL_MAJMIN:
                {
-                       struct stat st;
-
-                       if (loopcxt_get_device(lc)
-                           && stat(loopcxt_get_device(lc), &st) == 0
-                           && S_ISBLK(st.st_mode)
-                           && major(st.st_rdev) == LOOPDEV_MAJOR)
+                       dev_t dev = get_device_devno(lc, &st);
+                       if (dev)
                                xasprintf(&np, raw || json ? "%u:%u" :"%3u:%-3u",
-                                               major(st.st_rdev), minor(st.st_rdev));
+                                               major(dev), minor(dev));
+                       break;
+               }
+               case COL_MAJ: {
+                       dev_t dev = get_device_devno(lc, &st);
+                       if (dev)
+                               xasprintf(&np, "%u", major(dev));
+                       break;
+               }
+               case COL_MIN: {
+                       dev_t dev = get_device_devno(lc, &st);
+                       if (dev)
+                               xasprintf(&np, "%u", minor(dev));
                        break;
                }
                case COL_BACK_INO: