This adds a framework to check the /sys/fs/btrfs/features for the list of supported features by the btrfs kernel. Which I hope by using it the mkfs and btrfs-convert could tune to set features as supported by the running kernel.
Signed-off-by: Anand Jain <[email protected]> --- utils.c | 66 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++-------- utils.h | 1 + 2 files changed, 59 insertions(+), 8 deletions(-) diff --git a/utils.c b/utils.c index 24042e5..48a1989 100644 --- a/utils.c +++ b/utils.c @@ -577,22 +577,23 @@ out: */ static const struct btrfs_fs_feature { const char *name; + const char *name_ker; u64 flag; const char *desc; const char *min_ker_ver; } mkfs_features[] = { - { "mixed-bg", BTRFS_FEATURE_INCOMPAT_MIXED_GROUPS, + { "mixed-bg", "mixed_groups", BTRFS_FEATURE_INCOMPAT_MIXED_GROUPS, "mixed data and metadata block groups", "2.7.31"}, - { "extref", BTRFS_FEATURE_INCOMPAT_EXTENDED_IREF, + { "extref", "extended_iref", BTRFS_FEATURE_INCOMPAT_EXTENDED_IREF, "increased hardlink limit per file to 65536", "3.7"}, - { "raid56", BTRFS_FEATURE_INCOMPAT_RAID56, + { "raid56", "raid56", BTRFS_FEATURE_INCOMPAT_RAID56, "raid56 extended format", "3.9"}, - { "skinny-metadata", BTRFS_FEATURE_INCOMPAT_SKINNY_METADATA, + { "skinny-metadata", "skinny_metadata", BTRFS_FEATURE_INCOMPAT_SKINNY_METADATA, "reduced-size metadata extent refs", "3.10"}, - { "no-holes", BTRFS_FEATURE_INCOMPAT_NO_HOLES, + { "no-holes", "no_holes", BTRFS_FEATURE_INCOMPAT_NO_HOLES, "no explicit hole extents for files", "3.14"}, /* Keep this one last */ - { "list-all", BTRFS_FEATURE_LIST_ALL, NULL } + { "list-all", "", BTRFS_FEATURE_LIST_ALL, NULL } }; static int parse_one_fs_feature(const char *name, u64 *flags) @@ -602,10 +603,12 @@ static int parse_one_fs_feature(const char *name, u64 *flags) for (i = 0; i < ARRAY_SIZE(mkfs_features); i++) { if (name[0] == '^' && - !strcmp(mkfs_features[i].name, name + 1)) { + (!strcmp(mkfs_features[i].name, name + 1) || + !strcmp(mkfs_features[i].name_ker, name + 1))) { *flags &= ~ mkfs_features[i].flag; found = 1; - } else if (!strcmp(mkfs_features[i].name, name)) { + } else if (!strcmp(mkfs_features[i].name, name) || + !strcmp(mkfs_features[i].name_ker, name)) { *flags |= mkfs_features[i].flag; found = 1; } @@ -3147,3 +3150,50 @@ u64 btrfs_features_allowed_by_kernel(void) } return (features); } + +int check_or_load_btrfs_ko() +{ + int fd; + + /* + * open will load btrfs kernel module if its not loaded, + * and if the kernel has CONFIG auto load set? + */ + fd = open("/dev/btrfs-control", O_RDONLY); + if (fd < 0) + return -errno; + + close(fd); + return 0; +} + +int btrfs_features_allowed_by_sysfs(u64 *features) +{ + int ret; + DIR *dir; + struct dirent *ent; + + ret = check_or_load_btrfs_ko(); + if (ret) { + /* returns, -errno */ + return ret; + } + + dir = opendir("/sys/fs/btrfs/features"); + if (!dir) { + /* + * An old kernel which does not support sysfs/features + */ + return -errno; + } + + *features = 0; + while((ent = readdir(dir)) != NULL) { + if (!strcmp(".", ent->d_name) || + !strcmp("..", ent->d_name)) + continue; + parse_one_fs_feature(ent->d_name, features); + } + closedir(dir); + return 0; +} diff --git a/utils.h b/utils.h index 9044643..af0aa31 100644 --- a/utils.h +++ b/utils.h @@ -105,6 +105,7 @@ 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); +int btrfs_features_allowed_by_sysfs(u64 *features); struct btrfs_mkfs_config { char *label; -- 2.6.2 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
