diff options
| author | Daeho Jeong <daehojeong@google.com> | 2021-09-29 11:12:03 -0700 |
|---|---|---|
| committer | Jaegeuk Kim <jaegeuk@kernel.org> | 2021-10-26 14:04:30 -0700 |
| commit | 6691d940b0e09dd1564130e7a354d6deaf05d009 (patch) | |
| tree | ae609ea58abdfd7ce7c73e72f82d39226f2de3a9 /fs/f2fs/segment.c | |
| parent | 84eab2a899f28137e51a36861ed2df9579f54ebe (diff) | |
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..<max_fragment_chunk>
blocks in a chunk and make a hole in the length of
1..<max_fragment_hole> by turns in a newly allocated
free segment. Plus, this mode implicitly enables
"fragment:segment" option for more randomness.
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Daeho Jeong <daehojeong@google.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Diffstat (limited to 'fs/f2fs/segment.c')
| -rw-r--r-- | fs/f2fs/segment.c | 20 |
1 files changed, 18 insertions, 2 deletions
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c index 3189537a19dc..bdaf5fbdfb18 100644 --- a/fs/f2fs/segment.c +++ b/fs/f2fs/segment.c @@ -15,6 +15,7 @@ #include <linux/timer.h> #include <linux/freezer.h> #include <linux/sched/signal.h> +#include <linux/random.h> #include "f2fs.h" #include "segment.h" @@ -2649,6 +2650,8 @@ static unsigned int __get_next_segno(struct f2fs_sb_info *sbi, int type) unsigned short seg_type = curseg->seg_type; sanity_check_seg_type(sbi, seg_type); + if (f2fs_need_rand_seg(sbi)) + return prandom_u32() % (MAIN_SECS(sbi) * sbi->segs_per_sec); /* if segs_per_sec is large than 1, we need to keep original policy. */ if (__is_large_section(sbi)) @@ -2700,6 +2703,9 @@ static void new_curseg(struct f2fs_sb_info *sbi, int type, bool new_sec) curseg->next_segno = segno; reset_curseg(sbi, type, 1); curseg->alloc_type = LFS; + if (F2FS_OPTION(sbi).fs_mode == FS_MODE_FRAGMENT_BLK) + curseg->fragment_remained_chunk = + prandom_u32() % sbi->max_fragment_chunk + 1; } static int __next_free_blkoff(struct f2fs_sb_info *sbi, @@ -2726,12 +2732,22 @@ static int __next_free_blkoff(struct f2fs_sb_info *sbi, static void __refresh_next_blkoff(struct f2fs_sb_info *sbi, struct curseg_info *seg) { - if (seg->alloc_type == SSR) + if (seg->alloc_type == SSR) { seg->next_blkoff = __next_free_blkoff(sbi, seg->segno, seg->next_blkoff + 1); - else + } else { seg->next_blkoff++; + if (F2FS_OPTION(sbi).fs_mode == FS_MODE_FRAGMENT_BLK) { + /* To allocate block chunks in different sizes, use random number */ + if (--seg->fragment_remained_chunk <= 0) { + seg->fragment_remained_chunk = + prandom_u32() % sbi->max_fragment_chunk + 1; + seg->next_blkoff += + prandom_u32() % sbi->max_fragment_hole + 1; + } + } + } } bool f2fs_segment_has_free_slot(struct f2fs_sb_info *sbi, int segno) |