From 6691d940b0e09dd1564130e7a354d6deaf05d009 Mon Sep 17 00:00:00 2001 From: Daeho Jeong Date: Wed, 29 Sep 2021 11:12:03 -0700 Subject: f2fs: introduce fragment allocation mode mount option Added two options into "mode=" mount option to make it possible for developers to simulate filesystem fragmentation/after-GC situation itself. The developers use these modes to understand filesystem fragmentation/after-GC condition well, and eventually get some insights to handle them better. "fragment:segment": f2fs allocates a new segment in ramdom position. With this, we can simulate the after-GC condition. "fragment:block" : We can scatter block allocation with "max_fragment_chunk" and "max_fragment_hole" sysfs nodes. f2fs will allocate 1.. blocks in a chunk and make a hole in the length of 1.. by turns in a newly allocated free segment. Plus, this mode implicitly enables "fragment:segment" option for more randomness. Reviewed-by: Chao Yu Signed-off-by: Daeho Jeong Signed-off-by: Jaegeuk Kim --- fs/f2fs/gc.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'fs/f2fs/gc.c') diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c index 77391e3b7d68..a946ce0ead34 100644 --- a/fs/f2fs/gc.c +++ b/fs/f2fs/gc.c @@ -14,6 +14,7 @@ #include #include #include +#include #include "f2fs.h" #include "node.h" @@ -257,7 +258,9 @@ static void select_policy(struct f2fs_sb_info *sbi, int gc_type, p->max_search = sbi->max_victim_search; /* let's select beginning hot/small space first in no_heap mode*/ - if (test_opt(sbi, NOHEAP) && + if (f2fs_need_rand_seg(sbi)) + p->offset = prandom_u32() % (MAIN_SECS(sbi) * sbi->segs_per_sec); + else if (test_opt(sbi, NOHEAP) && (type == CURSEG_HOT_DATA || IS_NODESEG(type))) p->offset = 0; else -- cgit v1.2.3