It's a preparation to add Btrfs CPU affinity support. First, create a
new struct named `btrfs_cpu_set` to contain CPU affinity information.
Then, create helpers to allocate, parse, and free them.
Signed-off-by: Ammar Faizi <ammarfaizi2@xxxxxxxxxxx>
---
fs/btrfs/fs.c | 97 +++++++++++++++++++++++++++++++++++++++++++++++++++
fs/btrfs/fs.h | 7 ++++
2 files changed, 104 insertions(+)
diff --git a/fs/btrfs/fs.c b/fs/btrfs/fs.c
index 31c1648bc0b46922..283d153d4491289c 100644
--- a/fs/btrfs/fs.c
+++ b/fs/btrfs/fs.c
@@ -96,3 +96,100 @@ void __btrfs_clear_fs_compat_ro(struct btrfs_fs_info *fs_info, u64 flag,
set_bit(BTRFS_FS_FEATURE_CHANGED, &fs_info->flags);
}
}
+
+/*
+ * The user can't use the taskset pattern because ',' is used as
+ * the mount option delimiter. They can use the same taskset pattern,
+ * but replace the ',' with '.' and we will replace it back to
+ * ',', so the cpulist_parse() can recognize it.
+ *
+ * For example, in taskset cmd, they do:
+ * taskset -c 1,4,7 /bin/ls
+ *
+ * The equivalent CPU mask for the btrfs mount option will be:
+ * wq_cpu_set=1.4.7
+ *
+ * Mark these as __cold to avoid the code bloat from overoptimizing
+ * the loop.
+ */
+__cold static void cpulist_dot_to_comma(char *set)
+{
+ while (*set) {
+ if (*set == '.')
+ *set = ',';
+ set++;
+ }
+}
+
+__cold static void cpulist_comma_to_dot(char *set)
+{
+ while (*set) {
+ if (*set == ',')
+ *set = '.';
+ set++;
+ }
+}
+
+void btrfs_destroy_cpu_set(struct btrfs_cpu_set *cpu_set)
+{
+ if (!cpu_set)
+ return;
+
+ free_cpumask_var(cpu_set->mask);
+ kfree(cpu_set->mask_str);
+ kfree(cpu_set);
+}
+
+/*
+ * Only called from btrfs_parse_cpu_set().
+ */
+static struct btrfs_cpu_set *btrfs_alloc_cpu_set(void)
+{
+ struct btrfs_cpu_set *cpu_set;
+
+ cpu_set = kmalloc(sizeof(*cpu_set), GFP_KERNEL);
+ if (!cpu_set)
+ return NULL;
+
+ if (!alloc_cpumask_var(&cpu_set->mask, GFP_KERNEL)) {
+ kfree(cpu_set);
+ return NULL;
+ }
+
+ cpu_set->mask_str = NULL;
+ return cpu_set;
+}
+
+int btrfs_parse_cpu_set(struct btrfs_cpu_set **cpu_set_p, const char *mask_str)
+{
+ struct btrfs_cpu_set *cpu_set;
+ int ret;
+
+ cpu_set = btrfs_alloc_cpu_set();
+ if (!cpu_set)
+ return -ENOMEM;
+
+ cpu_set->mask_str = kstrdup(mask_str, GFP_KERNEL);
+ if (!cpu_set->mask_str) {
+ ret = -ENOMEM;
+ goto out_fail;
+ }
+
+ cpulist_dot_to_comma(cpu_set->mask_str);
+ ret = cpulist_parse(cpu_set->mask_str, cpu_set->mask);
+ if (ret)
+ goto out_fail;
+
+ if (cpumask_empty(cpu_set->mask)) {
+ ret = -EINVAL;
+ goto out_fail;
+ }
+
+ cpulist_comma_to_dot(cpu_set->mask_str);
+ *cpu_set_p = cpu_set;
+ return 0;
+
+out_fail:
+ btrfs_destroy_cpu_set(cpu_set);
+ return ret;
+}
diff --git a/fs/btrfs/fs.h b/fs/btrfs/fs.h
index 6de61367b6686197..cbad856df197ccfd 100644
--- a/fs/btrfs/fs.h
+++ b/fs/btrfs/fs.h
@@ -356,6 +356,11 @@ struct btrfs_commit_stats {
u64 total_commit_dur;
};
+struct btrfs_cpu_set {
+ cpumask_var_t mask;
+ char *mask_str;
+};
+
struct btrfs_fs_info {
u8 chunk_tree_uuid[BTRFS_UUID_SIZE];
unsigned long flags;
@@ -876,6 +881,8 @@ void btrfs_exclop_start_unlock(struct btrfs_fs_info *fs_info);
void btrfs_exclop_finish(struct btrfs_fs_info *fs_info);
void btrfs_exclop_balance(struct btrfs_fs_info *fs_info,
enum btrfs_exclusive_operation op);
+int btrfs_parse_cpu_set(struct btrfs_cpu_set **cpu_set_p, const char *mask_str);
+void btrfs_destroy_cpu_set(struct btrfs_cpu_set *cpu_set);
/* Compatibility and incompatibility defines */
void __btrfs_set_fs_incompat(struct btrfs_fs_info *fs_info, u64 flag,
--
Ammar Faizi
