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.
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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