mke2fs: Deprecate -K option, introduce discard/nodiscard

It would be nice to have consistent "discard" options in every system
tool (mount, fsck, mkfs) taking advantage of discards. Also "discard"
and "nodiscard" is more descriptive instead of just "-K" and can be
easily defaulted and it is something we can not do with "-K".

With this commit you need to specify extended option like this:

./mke2fs -T <fstype> -E nodiscard <device>

in order make a filesystem without discarding the device first. And

./mke2fs -T <fstype> -E discard <device>

respectively.

-K option is with this commit deprecated and should not be used anymore.

Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

diff --git a/misc/mke2fs.8.in b/misc/mke2fs.8.in
index b46e7e21c4ed2f0881c7a4a248797a7c976c4da1..c587d8104b3a743f5cc620cac9ba1c2e10b39972 100644 (file)
--- a/misc/mke2fs.8.in
+++ b/misc/mke2fs.8.in
@@ -45,9 +45,6 @@ mke2fs \- create an ext2/ext3/ext4 filesystem
 .I journal-options
 ]
 [
-.B \-K
-]
-[
 .B \-N
 .I number-of-inodes
 ]
@@ -240,6 +237,17 @@ enable lazy inode table initialization.
 .B test_fs
 Set a flag in the filesystem superblock indicating that it may be
 mounted using experimental kernel code, such as the ext4dev filesystem.
+.TP
+.BI discard
+Attempt to discard blocks at mkfs time (discarding blocks initially is useful
+on solid state devices and sparse / thin-provisioned storage). When the device
+advertises that discard also zeroes data (any subsequent read after the discard
+and before write returns zero), then mark all not-yet-zeroed inode tables as
+zeroed. This significantly speeds up filesystem initialization. This is set
+as default.
+.TP
+.BI nodiscard
+Do not attempt to discard blocks at mkfs time. This is the default.
 .RE
 .TP
 .BI \-f " fragment-size"
@@ -369,10 +377,6 @@ and may be no more than 102,400 filesystem blocks.
 @JDEV@.BR size " or " device
 @JDEV@options can be given for a filesystem.
 .TP
-.BI \-K
-Keep, do not attempt to discard blocks at mkfs time (discarding blocks initially
-is useful on solid state devices and sparse / thin-provisioned storage).
-.TP
 .BI \-l " filename"
 Read the bad blocks list from
 .IR filename .

diff --git a/misc/mke2fs.c b/misc/mke2fs.c
index 286f6ee43573e89091592feaeab4ddd011fa027e..ec4a810f3d187f2642259f25da8aac4a3b0ed335 100644 (file)
--- a/misc/mke2fs.c
+++ b/misc/mke2fs.c
@@ -806,6 +806,10 @@ static void parse_extended_opts(struct ext2_super_block *param,
                                lazy_itable_init = strtoul(arg, &p, 0);
                        else
                                lazy_itable_init = 1;
+               } else if (!strcmp(token, "discard")) {
+                       discard = 1;
+               } else if (!strcmp(token, "nodiscard")) {
+                       discard = 0;
                } else {
                        r_usage++;
                        badopt = token;
@@ -821,7 +825,9 @@ static void parse_extended_opts(struct ext2_super_block *param,
                        "\tstripe-width=<RAID stride * data disks in blocks>\n"
                        "\tresize=<resize maximum size in blocks>\n"
                        "\tlazy_itable_init=<0 to disable, 1 to enable>\n"
-                       "\ttest_fs\n\n"),
+                       "\ttest_fs\n"
+                       "\tdiscard\n"
+                       "\tnodiscard\n\n"),
                        badopt ? badopt : "");
                free(buf);
                exit(1);
@@ -1301,6 +1307,10 @@ static void PRS(int argc, char *argv[])
                        parse_journal_opts(optarg);
                        break;
                case 'K':
+                       fprintf(stderr, _("Warning: -K option is deprecated and "
+                                         "should not be used anymore. Use "
+                                         "\'-E nodiscard\' extended option "
+                                         "instead!\n"));
                        discard = 0;
                        break;
                case 'j':