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@xxxxxxx>
> ---
>
> 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;
>
--
To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
