sfdisk: add --no-tell-kernel

The option forces sfdisk to not call re-read partitions ioctl after
write PT.

Requested-by: Scott Moser <smoser@ubuntu.com>
Signed-off-by: Karel Zak <kzak@redhat.com>

diff --git a/disk-utils/sfdisk.8 b/disk-utils/sfdisk.8
index adbd138901d226792fe2d3ce0a2524673df5cf64..fcde8726b2bcae37403969250fc99224841740ad 100644 (file)
--- a/disk-utils/sfdisk.8
+++ b/disk-utils/sfdisk.8
@@ -158,6 +158,11 @@ Do everything except writing to the device.
 .B \-\-no\-reread
 Do not check through the re-read-partition-table ioctl whether the device is in use.
 .TP
+.B \-\-no\-tell\-kernel
+Don't tell the kernel about partition changes. This option is recommended together
+with \fB\-\-no\-reread\fR to modify a partition on used disk. The modified partition
+should not be used (e.g. mounted).
+.TP
 .BR \-O , " \-\-backup\-file " \fIpath
 Override the default backup file name.  Note that the device name and offset
 are always appended to the file name.

diff --git a/disk-utils/sfdisk.c b/disk-utils/sfdisk.c
index a97c5854db442d1e185b7db0c990abe44eb4a085..1f14f2c120b0f9aed83320da30be85803ca28648 100644 (file)
--- a/disk-utils/sfdisk.c
+++ b/disk-utils/sfdisk.c
@@ -110,6 +110,7 @@ struct sfdisk {
                     append : 1,        /* don't create new PT, append partitions only */
                     json : 1,          /* JSON dump */
                     movedata: 1,       /* move data after resize */
+                    notell : 1,        /* don't tell kernel aout new PT */
                     noact  : 1;        /* do not write to device */
 };
 
@@ -535,11 +536,13 @@ static int write_changes(struct sfdisk *sf)
                        rc = move_partition_data(sf, sf->partno, sf->orig_pa);
                if (!rc) {
                        fdisk_info(sf->cxt, _("\nThe partition table has been altered."));
-                       fdisk_reread_partition_table(sf->cxt);
+                       if (!sf->notell)
+                               fdisk_reread_partition_table(sf->cxt);
                }
        }
        if (!rc)
-               rc = fdisk_deassign_device(sf->cxt, sf->noact); /* no-sync when no-act */
+               rc = fdisk_deassign_device(sf->cxt,
+                               sf->noact || sf->notell);       /* no-sync */
        return rc;
 }
 
@@ -1824,6 +1827,7 @@ static void __attribute__ ((__noreturn__)) usage(FILE *out)
        fputs(_(" -N, --partno <num>        specify partition number\n"), out);
        fputs(_(" -n, --no-act              do everything except write to device\n"), out);
        fputs(_("     --no-reread           do not check whether the device is in use\n"), out);
+       fputs(_("     --no-tell-kernel      do not tell kernel about changes\n"), out);
        fputs(_(" -O, --backup-file <path>  override default backup file name\n"), out);
        fputs(_(" -o, --output <list>       output columns\n"), out);
        fputs(_(" -q, --quiet               suppress extra info messages\n"), out);
@@ -1871,7 +1875,8 @@ int main(int argc, char *argv[])
                OPT_BYTES,
                OPT_COLOR,
                OPT_MOVEDATA,
-               OPT_DELETE
+               OPT_DELETE,
+               OPT_NOTELL
        };
 
        static const struct option longopts[] = {
@@ -1893,6 +1898,7 @@ int main(int argc, char *argv[])
                { "list-types", no_argument,    NULL, 'T' },
                { "no-act",  no_argument,       NULL, 'n' },
                { "no-reread", no_argument,     NULL, OPT_NOREREAD },
+               { "no-tell-kernel", no_argument, NULL, OPT_NOTELL },
                { "move-data", optional_argument, NULL, OPT_MOVEDATA },
                { "output",  required_argument, NULL, 'o' },
                { "partno",  required_argument, NULL, 'N' },
@@ -2059,6 +2065,9 @@ int main(int argc, char *argv[])
                case OPT_DELETE:
                        sf->act = ACT_DELETE;
                        break;
+               case OPT_NOTELL:
+                       sf->notell = 1;
+                       break;
                default:
                        usage(stderr);
                }