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Message-ID: <alpine.LFD.2.00.1011181058230.15886@dhcp-lab-213.englab.brq.redhat.com>
Date: Thu, 18 Nov 2010 11:00:42 +0100 (CET)
From: Lukas Czerner <lczerner@...hat.com>
To: Eric Sandeen <sandeen@...hat.com>
cc: Lukas Czerner <lczerner@...hat.com>, linux-ext4@...r.kernel.org,
tytso@....edu, adilger@...ger.ca
Subject: Re: [PATCH 5/7] mke2fs: Change -K option to discard/nodiscard
On Tue, 16 Nov 2010, Eric Sandeen wrote:
> On 10/26/10 12:54 PM, Lukas Czerner wrote:
> > 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.
> >
> > Signed-off-by: Lukas Czerner <lczerner@...hat.com>
> > ---
> > misc/mke2fs.8.in | 18 +++++++++++-------
> > misc/mke2fs.c | 13 ++++++++-----
> > 2 files changed, 19 insertions(+), 12 deletions(-)
> >
> > diff --git a/misc/mke2fs.8.in b/misc/mke2fs.8.in
> > index b46e7e2..6b437bc 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
> > +advertise that discard also zeroes data (any subsequent read after the discard
>
> advertises
>
> > +and before write returns zero), then mark all not-yet-zeroed inode table as
>
> inode tables
>
> > +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" perhaps. (I'm not sure any other -E option has
> "no"-variants, so I'm not sure this is really needed, esp. for 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@...ions 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
>
> maybe keep this and mark as deprecated? Not sure how Ted handles deprecated
> options. This one didn't live long ;)
>
> > .BI \-l " filename"
> > Read the bad blocks list from
> > .IR filename .
> > diff --git a/misc/mke2fs.c b/misc/mke2fs.c
> > index 0980045..32e3a2b 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);
> > @@ -1168,7 +1174,7 @@ static void PRS(int argc, char *argv[])
> > }
> >
> > while ((c = getopt (argc, argv,
> > - "b:cf:g:G:i:jl:m:no:qr:s:t:vE:FI:J:KL:M:N:O:R:ST:U:V")) != EOF) {
> > + "b:cf:g:G:i:jl:m:no:qr:s:t:vE:FI:J:L:M:N:O:R:ST:U:V")) != EOF) {
>
> again, up to Ted whether we can drop an option like this.
This is a old version, I did send the new one "mke2fs: Deprecate -K
option, introduce discard/nodiscard" a while ago. Which removes -K
option from the man pages, and print out warning when it is used.
Thanks!
-Lukas
>
> > switch (c) {
> > case 'b':
> > blocksize = strtol(optarg, &tmp, 0);
> > @@ -1247,9 +1253,6 @@ static void PRS(int argc, char *argv[])
> > case 'J':
> > parse_journal_opts(optarg);
> > break;
> > - case 'K':
> > - discard = 0;
> > - break;
> > case 'j':
> > if (!journal_size)
> > journal_size = -1;
>
>
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