On 23 November 2015 at 12:56, Anand Jain <anand.j...@oracle.com> wrote:
> In the newer kernel, supported kernel features can be known from
> /sys/fs/btrfs/features
> however this interface was introduced only after 3.14, and most the
> incompatible FS features were introduce before 3.14.
>
> This patch proposes to maintain kernel version against the feature list,
> and so that will be the minimum kernel version needed to use the feature.
>
> Further, for features supported later than 3.14 this list can still be
> updated, so it serves as a repository which can be displayed for easy
> reference.
>
> Signed-off-by: Anand Jain <anand.j...@oracle.com>
> ---
> v2: Check for condition that what happens when we fail to read kernel
> version. Now the code will fail back to use the default as set by
> the progs.
>
> utils.c | 80
> ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-----
> utils.h | 1 +
> 2 files changed, 76 insertions(+), 5 deletions(-)
>
> diff --git a/utils.c b/utils.c
> index b754686..24042e5 100644
> --- a/utils.c
> +++ b/utils.c
> @@ -32,10 +32,12 @@
> #include <linux/loop.h>
> #include <linux/major.h>
> #include <linux/kdev_t.h>
> +#include <linux/version.h>
> #include <limits.h>
> #include <blkid/blkid.h>
> #include <sys/vfs.h>
> #include <sys/statfs.h>
> +#include <sys/utsname.h>
> #include <linux/magic.h>
>
> #include "kerncompat.h"
> @@ -567,21 +569,28 @@ out:
> return ret;
> }
>
> +/*
> + * min_ker_ver: update with minimum kernel version at which the feature
> + * was integrated into the mainline. For the transit period, that is
> + * feature not yet in mainline but in mailing list and for testing,
> + * please use "0.0" to indicate the same.
> + */
> static const struct btrfs_fs_feature {
> const char *name;
> u64 flag;
> const char *desc;
> + const char *min_ker_ver;
> } mkfs_features[] = {
> { "mixed-bg", BTRFS_FEATURE_INCOMPAT_MIXED_GROUPS,
> - "mixed data and metadata block groups" },
> + "mixed data and metadata block groups", "2.7.31"},
I think you mean 2.6.37 here.
67377734fd24c3 "Btrfs: add support for mixed data+metadata block groups"
Thanks,
Mike
> { "extref", BTRFS_FEATURE_INCOMPAT_EXTENDED_IREF,
> - "increased hardlink limit per file to 65536" },
> + "increased hardlink limit per file to 65536", "3.7"},
> { "raid56", BTRFS_FEATURE_INCOMPAT_RAID56,
> - "raid56 extended format" },
> + "raid56 extended format", "3.9"},
> { "skinny-metadata", BTRFS_FEATURE_INCOMPAT_SKINNY_METADATA,
> - "reduced-size metadata extent refs" },
> + "reduced-size metadata extent refs", "3.10"},
> { "no-holes", BTRFS_FEATURE_INCOMPAT_NO_HOLES,
> - "no explicit hole extents for files" },
> + "no explicit hole extents for files", "3.14"},
> /* Keep this one last */
> { "list-all", BTRFS_FEATURE_LIST_ALL, NULL }
> };
> @@ -3077,3 +3086,64 @@ unsigned int get_unit_mode_from_arg(int *argc, char
> *argv[], int df_mode)
>
> return unit_mode;
> }
> +
> +static int version_to_code(char *v)
> +{
> + int i = 0;
> + char *b[3] = {NULL};
> + char *save_b = NULL;
> +
> + for (b[i] = strtok_r(v, ".", &save_b);
> + b[i] != NULL;
> + b[i] = strtok_r(NULL, ".", &save_b))
> + i++;
> +
> + if (b[2] == NULL)
> + return KERNEL_VERSION(atoi(b[0]), atoi(b[1]), 0);
> + else
> + return KERNEL_VERSION(atoi(b[0]), atoi(b[1]), atoi(b[2]));
> +
> +}
> +
> +static int get_kernel_code()
> +{
> + int ret;
> + struct utsname utsbuf;
> + char *version;
> +
> + ret = uname(&utsbuf);
> + if (ret)
> + return -ret;
> +
> + if (!strlen(utsbuf.release))
> + return -EINVAL;
> +
> + version = strtok(utsbuf.release, "-");
> +
> + return version_to_code(version);
> +}
> +
> +u64 btrfs_features_allowed_by_kernel(void)
> +{
> + int i;
> + int local_kernel_code = get_kernel_code();
> + u64 features = 0;
> +
> + /*
> + * When system did not provide the kernel version then just
> + * return 0, the caller has to depend on the intelligence as
> + * per btrfs-progs version
> + */
> + if (local_kernel_code <= 0)
> + return 0;
> +
> + for (i = 0; i < ARRAY_SIZE(mkfs_features) - 1; i++) {
> + char *ver = strdup(mkfs_features[i].min_ker_ver);
> +
> + if (local_kernel_code >= version_to_code(ver))
> + features |= mkfs_features[i].flag;
> +
> + free(ver);
> + }
> + return (features);
> +}
> diff --git a/utils.h b/utils.h
> index 192f3d1..9044643 100644
> --- a/utils.h
> +++ b/utils.h
> @@ -104,6 +104,7 @@ void btrfs_list_all_fs_features(u64 mask_disallowed);
> char* btrfs_parse_fs_features(char *namelist, u64 *flags);
> void btrfs_process_fs_features(u64 flags);
> void btrfs_parse_features_to_string(char *buf, u64 flags);
> +u64 btrfs_features_allowed_by_kernel(void);
>
> struct btrfs_mkfs_config {
> char *label;
> --
> 2.6.2
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