Re: [PATCH v2 20/28] tune2fs: add inline_data feature in tune2fs

[Zheng Liu <gnehzuil.liu@gmail.com>]

On Tue, Dec 03, 2013 at 08:03:00PM -0800, Darrick J. Wong wrote:
> On Wed, Dec 04, 2013 at 11:55:36AM +0800, Zheng Liu wrote:
> > On Tue, Dec 03, 2013 at 02:29:46PM -0800, Darrick J. Wong wrote:
> > > On Tue, Dec 03, 2013 at 08:11:47PM +0800, Zheng Liu wrote:
> > > > From: Zheng Liu <wenqing.lz@taobao.com>
> > > > 
> > > > Inline_data can be enabled without ext_attr.  Hence we don't check it.
> > > > As doing in mke2fs we need to check inode size.
> > > > 
> > > > Now this feature only can be enabled because we may be out of space when
> > > > disabling it.  If this feature is disabled, we need to allocate a block
> > > > for every file and directory, and it might exhaust all space.
> > > 
> > > Could we at least try to turn off inlinedata and decline to clear the flag if
> > > we ENOSPC?
> > 
> > If we want to turn off inline_data, that means that we need to scan all
> > used inodes and try to expand it.  It isn't hard but I am wondering if
> > someone really want to disable this feature.  In my opinion, I really
> > want to enable inline_data feature by default when we believe it is very
> > stable because it will benefit for all desktop and Android users.
> 
> I guess that really depends on our testers -- on the one hand, I do most of my
> testing with scratch filesystems so on a practical level I will never need the
> ability to "undo" these sorts of things.
> 
> On the other hand, there's the argument that more people will test code if they
> think they can go back to the old system if the new one turns out to be a mess.
> 
> Same sort of reasoning applies to "why did you implement converting 64bit ->
> 32bit filesystems?" :)

Fair enough.  You convince me. :)

                                                - Zheng

> 
> --D
> > 
> >                                                 - Zheng
> > 
> > > 
> > > (Yes, that's more of a TODO feature request...)
> > > 
> > > > Signed-off-by: Theodore Ts'o <tytso@mit.edu>
> > > > Signed-off-by: Zheng Liu <wenqing.lz@taobao.com>
> > > > ---
> > > >  misc/tune2fs.8.in |    5 +++++
> > > >  misc/tune2fs.c    |   16 +++++++++++++++-
> > > >  2 files changed, 20 insertions(+), 1 deletion(-)
> > > > 
> > > > diff --git a/misc/tune2fs.8.in b/misc/tune2fs.8.in
> > > > index 55c6dd9..78f965b 100644
> > > > --- a/misc/tune2fs.8.in
> > > > +++ b/misc/tune2fs.8.in
> > > > @@ -531,6 +531,11 @@ Setting the filesystem feature is equivalent to using the
> > > >  .B \-j
> > > >  option.
> > > >  .TP
> > > > +.B inline_data
> > > > +Allow data to be stored in the inode and extented attribute area.
> > > 
> > > "extended"
> > > 
> > > --D
> > > 
> > > > +.B Tune2fs
> > > > +only supports setting this filesystem feature.
> > > > +.TP
> > > >  .B large_file
> > > >  Filesystem can contain files that are greater than 2GB.  (Modern kernels
> > > >  set this feature automatically when a file > 2GB is created.)
> > > > diff --git a/misc/tune2fs.c b/misc/tune2fs.c
> > > > index 95c1886..1952081 100644
> > > > --- a/misc/tune2fs.c
> > > > +++ b/misc/tune2fs.c
> > > > @@ -140,7 +140,8 @@ static __u32 ok_features[3] = {
> > > >  	EXT2_FEATURE_INCOMPAT_FILETYPE |
> > > >  		EXT3_FEATURE_INCOMPAT_EXTENTS |
> > > >  		EXT4_FEATURE_INCOMPAT_FLEX_BG |
> > > > -		EXT4_FEATURE_INCOMPAT_MMP,
> > > > +		EXT4_FEATURE_INCOMPAT_MMP |
> > > > +		EXT4_FEATURE_INCOMPAT_INLINE_DATA,
> > > >  	/* R/O compat */
> > > >  	EXT2_FEATURE_RO_COMPAT_LARGE_FILE |
> > > >  		EXT4_FEATURE_RO_COMPAT_HUGE_FILE|
> > > > @@ -1083,6 +1084,19 @@ mmp_error:
> > > >  		disable_uninit_bg(fs,
> > > >  				EXT4_FEATURE_RO_COMPAT_GDT_CSUM);
> > > >  
> > > > +	if (FEATURE_ON(E2P_FEATURE_INCOMPAT,
> > > > +		       EXT4_FEATURE_INCOMPAT_INLINE_DATA)) {
> > > > +		/*
> > > > +		 * Check inode size.  If inode size is 128, tell user that
> > > > +		 * inline data is useless.
> > > > +		 */
> > > > +		if (EXT2_INODE_SIZE(fs->super) == EXT2_GOOD_OLD_INODE_SIZE) {
> > > > +			fputs(_("The inode size is too small to "
> > > > +				"store inline data.\n"), stderr);
> > > > +			return 1;
> > > > +		}
> > > > +	}
> > > > +
> > > >  	if (FEATURE_ON(E2P_FEATURE_RO_INCOMPAT,
> > > >  				EXT4_FEATURE_RO_COMPAT_QUOTA)) {
> > > >  		/*
> > > > -- 
> > > > 1.7.9.7
> > > > 
> > > > --
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