thr3ads.net - Btrfs devel - [RFC][PATCH] btrfs-progs: mkfs: add -O option to specify fs features [Feb 2013]

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David Sterba

2013-Feb-19 11:16 UTC

[RFC][PATCH] btrfs-progs: mkfs: add -O option to specify fs features

Extend mkfs options to specify optional or potentially backwards
incompatible features. Use it for extended references.

Signed-off-by: David Sterba <dsterba@suse.cz>
---

The RFC is for the option name, as there does not seem to be a common name
amongst other mkfses.


 man/mkfs.btrfs.8.in |  7 +++++++
 mkfs.c              | 14 ++++++++++++--
 2 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/man/mkfs.btrfs.8.in b/man/mkfs.btrfs.8.in
index 41163e0..5ff4e2c 100644
--- a/man/mkfs.btrfs.8.in
+++ b/man/mkfs.btrfs.8.in
@@ -15,6 +15,7 @@ mkfs.btrfs \- create a btrfs filesystem
 [ \fB\-s\fP\fI sectorsize\fP ]
 [ \fB\-r\fP\fI rootdir\fP ]
 [ \fB\-K\fP ]
+[ \fB\-O\fP\fI feature1,feature2,...\fP ]
 [ \fB\-h\fP ]
 [ \fB\-V\fP ]
 \fI device\fP [ \fIdevice ...\fP ]
@@ -76,6 +77,12 @@ Specify a directory to copy into the newly created fs.
 \fB\-K\fR, \fB\-\-nodiscard \fR
 Do not perform whole device TRIM operation by default.
 .TP
+\fB\-O\fR, \fB\-\-features \fIfeature1,feature2,...\fR
+A list of filesystem features turned on at mkfs time. Not all features are
+supported by old kernels.
+
+extref - allow creating more hardlinks per file (the upper limit is 65535)
+.TP
 \fB\-V\fR, \fB\-\-version\fR
 Print the \fBmkfs.btrfs\fP version and exit.
 .SH UNIT
diff --git a/mkfs.c b/mkfs.c
index 5ece186..dd1e317 100644
--- a/mkfs.c
+++ b/mkfs.c
@@ -335,6 +335,7 @@ static void print_usage(void)
 	fprintf(stderr, "\t -s --sectorsize min block allocation\n");
 	fprintf(stderr, "\t -r --rootdir the source directory\n");
 	fprintf(stderr, "\t -K --nodiscard do not perform whole device
TRIM\n");
+	fprintf(stderr, "\t -O --features coma separated list of filesystem
features\n");
 	fprintf(stderr, "\t -V --version print the mkfs.btrfs version and
exit\n");
 	fprintf(stderr, "%s\n", BTRFS_BUILD_VERSION);
 	exit(1);
@@ -395,6 +396,7 @@ static struct option long_options[] = {
 	{ "version", 0, NULL, ''V'' },
 	{ "rootdir", 1, NULL, ''r'' },
 	{ "nodiscard", 0, NULL, ''K'' },
+	{ "features", 0, NULL, ''O'' },
 	{ 0, 0, 0, 0}
 };
 
@@ -1376,10 +1378,11 @@ int main(int ac, char **av)
 	char *pretty_buf;
 	struct btrfs_super_block *super;
 	u64 flags;
+	char *features = strdup("");
 
 	while(1) {
 		int c;
-		c = getopt_long(ac, av, "A:b:fl:n:s:m:d:L:r:VMK", long_options,
+		c = getopt_long(ac, av, "A:b:fl:n:s:m:d:L:O:r:VMK", long_options,
 				&option_index);
 		if (c < 0)
 			break;
@@ -1409,6 +1412,10 @@ int main(int ac, char **av)
 			case ''M'':
 				mixed = 1;
 				break;
+			case ''O'':
+				free(features);
+				features = strdup(optarg);
+				break;
 			case ''s'':
 				sectorsize = parse_size(optarg);
 				break;
@@ -1652,7 +1659,10 @@ raid_groups:
 
 	super = &root->fs_info->super_copy;
 	flags = btrfs_super_incompat_flags(super);
-	flags |= BTRFS_FEATURE_INCOMPAT_EXTENDED_IREF;
+	if (strstr(features, "extref") == 0) {
+		fprintf(stderr, "Turning ON incompat feature: extref (increased hardlink
limit per file)\n");
+		flags |= BTRFS_FEATURE_INCOMPAT_EXTENDED_IREF;
+	}
 
 	if (mixed)
 		flags |= BTRFS_FEATURE_INCOMPAT_MIXED_GROUPS;
-- 
1.8.0.2

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Eric Sandeen

2013-Feb-19 16:23 UTC

head link

Re: [RFC][PATCH] btrfs-progs: mkfs: add -O option to specify fs features

On 2/19/13 5:16 AM, David Sterba wrote:> Extend mkfs options to specify optional or potentially backwards
> incompatible features. Use it for extended references.
> 
> Signed-off-by: David Sterba <dsterba@suse.cz>
> ---
> 
> The RFC is for the option name, as there does not seem to be a common name
> amongst other mkfses.
What did you find when looking?

xfsprogs doesn''t really have a feature flag option per se; there are
just block,
inode, size, log, data etc. options which may trigger some feature set.

e2fsprogs has the rather -O feature -E extended-options set, and darned if I
could
tell you the difference ;)

but I think -O is the right option, unless you found other common
mkfs''s that
use something different.  When in doubt, e2fsprogs conventions probably win.  :)

-Eric
> 
>  man/mkfs.btrfs.8.in |  7 +++++++
>  mkfs.c              | 14 ++++++++++++--
>  2 files changed, 19 insertions(+), 2 deletions(-)
> 
> diff --git a/man/mkfs.btrfs.8.in b/man/mkfs.btrfs.8.in
> index 41163e0..5ff4e2c 100644
> --- a/man/mkfs.btrfs.8.in
> +++ b/man/mkfs.btrfs.8.in
> @@ -15,6 +15,7 @@ mkfs.btrfs \- create a btrfs filesystem
>  [ \fB\-s\fP\fI sectorsize\fP ]
>  [ \fB\-r\fP\fI rootdir\fP ]
>  [ \fB\-K\fP ]
> +[ \fB\-O\fP\fI feature1,feature2,...\fP ]
>  [ \fB\-h\fP ]
>  [ \fB\-V\fP ]
>  \fI device\fP [ \fIdevice ...\fP ]
> @@ -76,6 +77,12 @@ Specify a directory to copy into the newly created fs.
>  \fB\-K\fR, \fB\-\-nodiscard \fR
>  Do not perform whole device TRIM operation by default.
>  .TP
> +\fB\-O\fR, \fB\-\-features \fIfeature1,feature2,...\fR
> +A list of filesystem features turned on at mkfs time. Not all features are
> +supported by old kernels.
> +
> +extref - allow creating more hardlinks per file (the upper limit is 65535)
> +.TP
>  \fB\-V\fR, \fB\-\-version\fR
>  Print the \fBmkfs.btrfs\fP version and exit.
>  .SH UNIT
> diff --git a/mkfs.c b/mkfs.c
> index 5ece186..dd1e317 100644
> --- a/mkfs.c
> +++ b/mkfs.c
> @@ -335,6 +335,7 @@ static void print_usage(void)
>  	fprintf(stderr, "\t -s --sectorsize min block allocation\n");
>  	fprintf(stderr, "\t -r --rootdir the source directory\n");
>  	fprintf(stderr, "\t -K --nodiscard do not perform whole device
TRIM\n");
> +	fprintf(stderr, "\t -O --features coma separated list of filesystem
features\n");
>  	fprintf(stderr, "\t -V --version print the mkfs.btrfs version and
exit\n");
>  	fprintf(stderr, "%s\n", BTRFS_BUILD_VERSION);
>  	exit(1);
> @@ -395,6 +396,7 @@ static struct option long_options[] = {
>  	{ "version", 0, NULL, ''V'' },
>  	{ "rootdir", 1, NULL, ''r'' },
>  	{ "nodiscard", 0, NULL, ''K'' },
> +	{ "features", 0, NULL, ''O'' },
>  	{ 0, 0, 0, 0}
>  };
>  
> @@ -1376,10 +1378,11 @@ int main(int ac, char **av)
>  	char *pretty_buf;
>  	struct btrfs_super_block *super;
>  	u64 flags;
> +	char *features = strdup("");
>  
>  	while(1) {
>  		int c;
> -		c = getopt_long(ac, av, "A:b:fl:n:s:m:d:L:r:VMK",
long_options,
> +		c = getopt_long(ac, av, "A:b:fl:n:s:m:d:L:O:r:VMK",
long_options,
>  				&option_index);
>  		if (c < 0)
>  			break;
> @@ -1409,6 +1412,10 @@ int main(int ac, char **av)
>  			case ''M'':
>  				mixed = 1;
>  				break;
> +			case ''O'':
> +				free(features);
> +				features = strdup(optarg);
> +				break;
>  			case ''s'':
>  				sectorsize = parse_size(optarg);
>  				break;
> @@ -1652,7 +1659,10 @@ raid_groups:
>  
>  	super = &root->fs_info->super_copy;
>  	flags = btrfs_super_incompat_flags(super);
> -	flags |= BTRFS_FEATURE_INCOMPAT_EXTENDED_IREF;
> +	if (strstr(features, "extref") == 0) {
> +		fprintf(stderr, "Turning ON incompat feature: extref (increased
hardlink limit per file)\n");
> +		flags |= BTRFS_FEATURE_INCOMPAT_EXTENDED_IREF;
> +	}
>  
>  	if (mixed)
>  		flags |= BTRFS_FEATURE_INCOMPAT_MIXED_GROUPS;
> 
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David Sterba

2013-Feb-20 13:28 UTC

head link

Re: [RFC][PATCH] btrfs-progs: mkfs: add -O option to specify fs features

On Tue, Feb 19, 2013 at 10:23:05AM -0600, Eric Sandeen
wrote:> On 2/19/13 5:16 AM, David Sterba wrote:
> > The RFC is for the option name, as there does not seem to be a common
name
> > amongst other mkfses.
> 
> What did you find when looking?
I remember that extN uses -O and that was my first choice without much
thinking. While writing the changelog "all other mkfs use -O" I did
not
find this correct when looking to xfs and ocfs2 manpages.
> xfsprogs doesn''t really have a feature flag option per se; there
are just block,
> inode, size, log, data etc. options which may trigger some feature set.
Yeah, and this separation makes sense, as there are several options how
to tune the specific area.

My point is to turn on/off a whole filesystem feature via a single
option that cannot be enabled by a mount option or may make the
filesystem unmountable on older kernels due to incompat bits.
> e2fsprogs has the rather -O feature -E extended-options set, and darned if
I could
> tell you the difference ;)
> 
> but I think -O is the right option, unless you found other common
mkfs''s that
> use something different.  When in doubt, e2fsprogs conventions probably
win.  :)
Nothing so far, tried jfs, f2fs, hfs, reiserfs.

Thanks for your comment.


david
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Btrfs devel - Feb 2013 - [RFC][PATCH] btrfs-progs: mkfs: add -O option to specify fs features

[RFC][PATCH] btrfs-progs: mkfs: add -O option to specify fs features

Re: [RFC][PATCH] btrfs-progs: mkfs: add -O option to specify fs features

Re: [RFC][PATCH] btrfs-progs: mkfs: add -O option to specify fs features