Re: [PATCH v2] btrfs-progs: allow "none" to disable compression for convenience

[Satoru Takeuchi]

At Tue, 19 Sep 2017 17:14:27 +0200,
David Sterba wrote:
> 
> On Mon, Sep 18, 2017 at 09:41:17AM +0900, Satoru Takeuchi wrote:
> > At Sun, 17 Sep 2017 14:08:40 +0100,
> > Mike Fleetwood wrote:
> > > 
> > > On 17 September 2017 at 01:36, Satoru Takeuchi
> > >  wrote:
> > > > It's messy to use "" to disable compression. Introduce the new value 
> > > > "no"
> > > > which can also be used for this purpose.
> > > 
> > > From an English language point of view, "none" would be better.  None
> > > says the absence of, where as no is more general negative.
> > 
> > Thank you for your comment. How about is it?
> > 
> > ---
> > It's messy to use "" to disable compression. Introduce the new value "none"
> > which can also be used for this purpose.
> 
> I'd allow both values, 'no' and 'none', similar to the mount options,
> that also accept both (technically, the 'no' + anything is accepted for
> disabling compression).

But only "no" is writtein in man 5 btrfs.
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Re: [PATCH v2] btrfs-progs: allow "none" to disable compression for convenience

[Satoru Takeuchi]

At Tue, 19 Sep 2017 17:14:27 +0200,
David Sterba wrote:
> 
> On Mon, Sep 18, 2017 at 09:41:17AM +0900, Satoru Takeuchi wrote:
> > At Sun, 17 Sep 2017 14:08:40 +0100,
> > Mike Fleetwood wrote:
> > > 
> > > On 17 September 2017 at 01:36, Satoru Takeuchi
> > >  wrote:
> > > > It's messy to use "" to disable compression. Introduce the new value 
> > > > "no"
> > > > which can also be used for this purpose.
> > > 
> > > From an English language point of view, "none" would be better.  None
> > > says the absence of, where as no is more general negative.
> > 
> > Thank you for your comment. How about is it?
> > 
> > ---
> > It's messy to use "" to disable compression. Introduce the new value "none"
> > which can also be used for this purpose.
> 
> I'd allow both values, 'no' and 'none', similar to the mount options,
> that also accept both (technically, the 'no' + anything is accepted for
> disabling compression).

As a result of reading "man 5 btrfs", now I prefer "no". It's used
to mean disabling compression there. On the other hand, "none" is
not used at all.

From man 5 btrfs:
===
...
FILE ATTRIBUTES
...
   compress, compress=type, compress-force, compress-force=type
   (default: off)

   Control BTRFS file data compression. Type may be specified as zlib, 
lzo or no (for no compression, used for remounting). If no type is specified, 
zlib is used. If
   compress-force is specified, all files will be compressed, whether 
or not they compress well.
...
   X
   no compression, permanently turn off compression on the given file, 
other compression mount options will not affect that
...
===

So David, please apply my v1 patcth if it looks good for you.

Thanks,
Satoru
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Re: [PATCH v2] btrfs-progs: allow "none" to disable compression for convenience

[David Sterba]

On Mon, Sep 18, 2017 at 09:41:17AM +0900, Satoru Takeuchi wrote:
> At Sun, 17 Sep 2017 14:08:40 +0100,
> Mike Fleetwood wrote:
> > 
> > On 17 September 2017 at 01:36, Satoru Takeuchi
> >  wrote:
> > > It's messy to use "" to disable compression. Introduce the new value "no"
> > > which can also be used for this purpose.
> > 
> > From an English language point of view, "none" would be better.  None
> > says the absence of, where as no is more general negative.
> 
> Thank you for your comment. How about is it?
> 
> ---
> It's messy to use "" to disable compression. Introduce the new value "none"
> which can also be used for this purpose.

I'd allow both values, 'no' and 'none', similar to the mount options,
that also accept both (technically, the 'no' + anything is accepted for
disabling compression).
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[PATCH v2] btrfs-progs: allow "none" to disable compression for convenience

[Satoru Takeuchi]

At Sun, 17 Sep 2017 14:08:40 +0100,
Mike Fleetwood wrote:
> 
> On 17 September 2017 at 01:36, Satoru Takeuchi
>  wrote:
> > It's messy to use "" to disable compression. Introduce the new value "no"
> > which can also be used for this purpose.
> 
> From an English language point of view, "none" would be better.  None
> says the absence of, where as no is more general negative.

Thank you for your comment. How about is it?

---
It's messy to use "" to disable compression. Introduce the new value "none"
which can also be used for this purpose.

Signed-off-by: Satoru Takeuchi 
---
 Documentation/btrfs-property.asciidoc | 2 +-
 props.c   | 6 --
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/Documentation/btrfs-property.asciidoc 
b/Documentation/btrfs-property.asciidoc
index 7ed6a7d..786af9b 100644
--- a/Documentation/btrfs-property.asciidoc
+++ b/Documentation/btrfs-property.asciidoc
@@ -43,7 +43,7 @@ read-only flag of subvolume: true or false
 label
 label of device
 compression
-compression setting for an inode: lzo, zlib, zstd, or "" (empty string)
+compression setting for an inode: lzo, zlib, zstd, none, or "" (empty string). 
Both none and "" are for disabling compression.
 
 *list* [-t ] ::
 Lists available properties with their descriptions for the given object.
diff --git a/props.c b/props.c
index a7e3e96..8d85181 100644
--- a/props.c
+++ b/props.c
@@ -142,9 +142,11 @@ static int prop_compression(enum prop_object_type type,
memcpy(xattr_name + XATTR_BTRFS_PREFIX_LEN, name, strlen(name));
xattr_name[XATTR_BTRFS_PREFIX_LEN + strlen(name)] = '\0';
 
-   if (value)
+   if (value) {
+   if (!strcmp(value, "none"))
+   value = "";
sret = fsetxattr(fd, xattr_name, value, strlen(value), 0);
-   else
+   } else
sret = fgetxattr(fd, xattr_name, NULL, 0);
if (sret < 0) {
ret = -errno;
-- 
2.7.4

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