Re: [PATCH 1/2] Add discard/nodiscard mount option for ext3

[Ric Wheeler <rwheeler@xxxxxxxxxx>]

On 07/12/2010 11:19 AM, Jan Kara wrote:
> > Those mount option has the same meaning as in ext4 file system. It
> > provide a way to enable/disable file system's trim support. The trim
> > support is off by default, thus nodiscard option is not actually
> > necessary.
>    I kind of miss why ext3 should have a 'discard' mount option. When
> user calls DISCARD ioctl on the filesystem, then he probably wants
> discard to be performed.
>
> 								Honza


Did you see Lukas' second patch for batched discards in ext3?

Ric

> > Signed-off-by: Lukas Czerner<lczerner@xxxxxxxxxx>
> > ---
> >   fs/ext3/super.c         |   14 +++++++++++++-
> >   include/linux/ext3_fs.h |    1 +
> >   2 files changed, 14 insertions(+), 1 deletions(-)
> >
> > diff --git a/fs/ext3/super.c b/fs/ext3/super.c
> > index 1bee604..6baf7ef 100644
> > --- a/fs/ext3/super.c
> > +++ b/fs/ext3/super.c
> > @@ -662,6 +662,9 @@ static int ext3_show_options(struct seq_file *seq, struct vfsmount *vfs)
> >   	if (test_opt(sb, DATA_ERR_ABORT))
> >   		seq_puts(seq, ",data_err=abort");
> >
> > +	if (test_opt(sb, DISCARD))
> > +		seq_puts(seq, ",discard");
> > +
> >   	if (test_opt(sb, NOLOAD))
> >   		seq_puts(seq, ",norecovery");
> >
> > @@ -811,7 +814,8 @@ enum {
> >   	Opt_usrjquota, Opt_grpjquota, Opt_offusrjquota, Opt_offgrpjquota,
> >   	Opt_jqfmt_vfsold, Opt_jqfmt_vfsv0, Opt_jqfmt_vfsv1, Opt_quota,
> >   	Opt_noquota, Opt_ignore, Opt_barrier, Opt_err, Opt_resize,
> > -	Opt_usrquota, Opt_grpquota
> > +	Opt_usrquota, Opt_grpquota,
> > +	Opt_discard, Opt_nodiscard,
> >   };
> >
> >   static const match_table_t tokens = {
> > @@ -866,6 +870,8 @@ static const match_table_t tokens = {
> >   	{Opt_usrquota, "usrquota"},
> >   	{Opt_barrier, "barrier=%u"},
> >   	{Opt_resize, "resize"},
> > +	{Opt_discard, "discard"},
> > +	{Opt_nodiscard, "nodiscard"},
> >   	{Opt_err, NULL},
> >   };
> >
> > @@ -1242,6 +1248,12 @@ set_qf_format:
> >   		case Opt_bh:
> >   			clear_opt(sbi->s_mount_opt, NOBH);
> >   			break;
> > +		case Opt_discard:
> > +			set_opt(sbi->s_mount_opt, DISCARD);
> > +			break;
> > +		case Opt_nodiscard:
> > +			clear_opt(sbi->s_mount_opt, DISCARD);
> > +			break;
> >   		default:
> >   			ext3_msg(sb, KERN_ERR,
> >   				"error: unrecognized mount option \"%s\" "
> > diff --git a/include/linux/ext3_fs.h b/include/linux/ext3_fs.h
> > index 5f494b4..f3fdd94 100644
> > --- a/include/linux/ext3_fs.h
> > +++ b/include/linux/ext3_fs.h
> > @@ -406,6 +406,7 @@ struct ext3_inode {
> >   #define EXT3_MOUNT_GRPQUOTA		0x200000 /* "old" group quota */
> >   #define EXT3_MOUNT_DATA_ERR_ABORT	0x400000 /* Abort on file data write
> >   						  * error in ordered mode */
> > +#define EXT3_MOUNT_DISCARD		0x800000 /* Issue DISCARD requests */
> >
> >   /* Compatibility, for having both ext2_fs.h and ext3_fs.h included at once */
> >   #ifndef _LINUX_EXT2_FS_H
> > --
> > 1.6.6.1
> >
> > --
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