f2fs: introduce gc_merge mount option
In this patch, we will add two new mount options: "gc_merge" and
"nogc_merge", when background_gc is on, "gc_merge" option can be
set to let background GC thread to handle foreground GC requests,
it can eliminate the sluggish issue caused by slow foreground GC
operation when GC is triggered from a process with limited I/O
and CPU resources.
Original idea is from Xiang.
Signed-off-by: Gao Xiang <xiang@kernel.org>
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index b482816..954b1fe 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -151,6 +151,8 @@ enum {
Opt_compress_chksum,
Opt_compress_mode,
Opt_atgc,
+ Opt_gc_merge,
+ Opt_nogc_merge,
Opt_err,
};
@@ -223,6 +225,8 @@ static match_table_t f2fs_tokens = {
{Opt_compress_chksum, "compress_chksum"},
{Opt_compress_mode, "compress_mode=%s"},
{Opt_atgc, "atgc"},
+ {Opt_gc_merge, "gc_merge"},
+ {Opt_nogc_merge, "nogc_merge"},
{Opt_err, NULL},
};
@@ -1073,6 +1077,12 @@ static int parse_options(struct super_block *sb, char *options, bool is_remount)
case Opt_atgc:
set_opt(sbi, ATGC);
break;
+ case Opt_gc_merge:
+ set_opt(sbi, GC_MERGE);
+ break;
+ case Opt_nogc_merge:
+ clear_opt(sbi, GC_MERGE);
+ break;
default:
f2fs_err(sbi, "Unrecognized mount option \"%s\" or missing value",
p);
@@ -1675,6 +1685,9 @@ static int f2fs_show_options(struct seq_file *seq, struct dentry *root)
else if (F2FS_OPTION(sbi).bggc_mode == BGGC_MODE_OFF)
seq_printf(seq, ",background_gc=%s", "off");
+ if (test_opt(sbi, GC_MERGE))
+ seq_puts(seq, ",gc_merge");
+
if (test_opt(sbi, DISABLE_ROLL_FORWARD))
seq_puts(seq, ",disable_roll_forward");
if (test_opt(sbi, NORECOVERY))
@@ -2038,7 +2051,8 @@ static int f2fs_remount(struct super_block *sb, int *flags, char *data)
* option. Also sync the filesystem.
*/
if ((*flags & SB_RDONLY) ||
- F2FS_OPTION(sbi).bggc_mode == BGGC_MODE_OFF) {
+ (F2FS_OPTION(sbi).bggc_mode == BGGC_MODE_OFF &&
+ !test_opt(sbi, GC_MERGE))) {
if (sbi->gc_thread) {
f2fs_stop_gc_thread(sbi);
need_restart_gc = true;
@@ -4012,7 +4026,8 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent)
* If filesystem is not mounted as read-only then
* do start the gc_thread.
*/
- if (F2FS_OPTION(sbi).bggc_mode != BGGC_MODE_OFF && !f2fs_readonly(sb)) {
+ if ((F2FS_OPTION(sbi).bggc_mode != BGGC_MODE_OFF ||
+ test_opt(sbi, GC_MERGE)) && !f2fs_readonly(sb)) {
/* After POR, we can run background GC thread.*/
err = f2fs_start_gc_thread(sbi);
if (err)