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@xxxxxxxxxx>
---
misc/mke2fs.8.in | 18 +++++++++++-------
misc/mke2fs.c | 12 +++++++++++-
2 files changed, 22 insertions(+), 8 deletions(-)
diff --git a/misc/mke2fs.8.in b/misc/mke2fs.8.in
index b46e7e2..c587d81 100644
--- 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 3c5d8b7..d63c27f 100644
--- a/misc/mke2fs.c
+++ b/misc/mke2fs.c
@@ -753,6 +753,10 @@ 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;
@@ -768,7 +772,9 @@ 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);
@@ -1248,6 +1254,10 @@ 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':
--
1.7.2.3
--
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