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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:fixed_block" : We can scatter block allocation with "fragment_chunk_size" and "fragment_hole_size" sysfs nodes. f2fs will allocate blocks in a chunk and make a hole in the length of by turns in a newly allocated free segment. "fragment:rand_block" : Working like "fragment:fixed_block" mode, but added some randomness to both chunk and hole size. So, f2fs will allocate 1.. blocks in a chunk and make a hole in the 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, f2fs implicitly enables "fragment:segment" option for more randomness in allocation in "fragment:rand_block". Signed-off-by: Daeho Jeong --- v4: implicitly enabled "fragment:segment" option only in "fragment:rand_block". v3: divided "fragment:block" mode and fixed a race condition related to making chunks. v2: changed mode name and added sysfs nodes to control the fragmentation pattern. --- Documentation/ABI/testing/sysfs-fs-f2fs | 24 ++++++++++++++++++++ Documentation/filesystems/f2fs.rst | 22 +++++++++++++++++++ fs/f2fs/f2fs.h | 20 +++++++++++++++-- fs/f2fs/gc.c | 5 ++++- fs/f2fs/segment.c | 29 +++++++++++++++++++++++-- fs/f2fs/segment.h | 1 + fs/f2fs/super.c | 14 ++++++++++++ fs/f2fs/sysfs.c | 20 +++++++++++++++++ 8 files changed, 130 insertions(+), 5 deletions(-) diff --git a/Documentation/ABI/testing/sysfs-fs-f2fs b/Documentation/ABI/testing/sysfs-fs-f2fs index f627e705e663..d56ecfd16abf 100644 --- a/Documentation/ABI/testing/sysfs-fs-f2fs +++ b/Documentation/ABI/testing/sysfs-fs-f2fs @@ -512,3 +512,27 @@ Date: July 2021 Contact: "Daeho Jeong" Description: You can control the multiplier value of bdi device readahead window size between 2 (default) and 256 for POSIX_FADV_SEQUENTIAL advise option. + +What: /sys/fs/f2fs//fragment_chunk_size +Date: August 2021 +Contact: "Daeho Jeong" +Description: With "mode=fragment:fixed_block" and "mode=fragment:rand_block" mount options, + we can scatter block allocation. Using this node, in "fragment:fixed_block" + mode, f2fs will allocate blocks in a chunk and make + a hole in the length of by turns in a newly allocated + free segment. Plus, in "fragment:rand_block" mode, f2fs will allocate + 1.. blocks in a chunk and make a hole in the length of + 1.. by turns. This value can be set between 1..512 and + the default value is 4. + +What: /sys/fs/f2fs//fragment_hole_size +Date: August 2021 +Contact: "Daeho Jeong" +Description: With "mode=fragment:fixed_block" and "mode=fragment:rand_block" mount options, + we can scatter block allocation. Using this node, in "fragment:fixed_block" + mode, f2fs will allocate blocks in a chunk and make + a hole in the length of by turns in a newly allocated + free segment. Plus, in "fragment:rand_block" mode, f2fs will allocate + 1.. blocks in a chunk and make a hole in the length of + 1.. by turns. This value can be set between 1..512 and + the default value is 4. diff --git a/Documentation/filesystems/f2fs.rst b/Documentation/filesystems/f2fs.rst index 09de6ebbbdfa..04ddae8754cc 100644 --- a/Documentation/filesystems/f2fs.rst +++ b/Documentation/filesystems/f2fs.rst @@ -201,6 +201,28 @@ fault_type=%d Support configuring fault injection type, should be mode=%s Control block allocation mode which supports "adaptive" and "lfs". In "lfs" mode, there should be no random writes towards main area. + "fragment:segment", "fragment:fixed_block" and "fragment:rand_block" + are newly added here. These are developer options for experiments + to make the filesystem fragmented or 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. + In "fragment:segment", f2fs allocates a new segment in ramdom + position. With this, we can simulate the after-GC condition. + In "fragment:fixed_block" and "fragment:rand_block", we can scatter + block allocation with "fragment_chunk_size" and "fragment_hole_size" + sysfs nodes. In "fragment:fixed_block" mode, f2fs will allocate + blocks in a chunk and make a hole in the length + of by turns in a newly allocated free segment. + But, in "fragment:rand_block" mode, f2fs adds some randomness to + both chunk and hole size. So, f2fs will allocate + 1.. blocks in a chunk and make a hole in the + length of 1.. by turns. With these, the newly + allocated blocks will be scattered throughout the whole partition. + Plus, f2fs implicitly enables "fragment:segment" option for more + randomness in allocation in "fragment:rand_block". + Please, use these options for your experiments and we strongly + recommend to re-format the filesystem after using these options. io_bits=%u Set the bit size of write IO requests. It should be set with "mode=lfs". usrquota Enable plain user disk quota accounting. diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h index c24f03e054cb..f9aa00b92222 100644 --- a/fs/f2fs/f2fs.h +++ b/fs/f2fs/f2fs.h @@ -1285,8 +1285,11 @@ enum { }; enum { - FS_MODE_ADAPTIVE, /* use both lfs/ssr allocation */ - FS_MODE_LFS, /* use lfs allocation only */ + FS_MODE_ADAPTIVE, /* use both lfs/ssr allocation */ + FS_MODE_LFS, /* use lfs allocation only */ + FS_MODE_FRAGMENT_SEG, /* segment fragmentation mode */ + FS_MODE_FRAGMENT_FIXED_BLK, /* fixed block fragmentation mode */ + FS_MODE_FRAGMENT_RAND_BLK, /* randomized block fragmentation mode */ }; enum { @@ -1757,6 +1760,9 @@ struct f2fs_sb_info { unsigned long seq_file_ra_mul; /* multiplier for ra_pages of seq. files in fadvise */ + int fragment_chunk_size; /* the chunk size for block fragmentation mode */ + int fragment_hole_size; /* the hole size for block fragmentation mode */ + #ifdef CONFIG_F2FS_FS_COMPRESSION struct kmem_cache *page_array_slab; /* page array entry */ unsigned int page_array_slab_size; /* default page array slab size */ @@ -3517,6 +3523,16 @@ unsigned int f2fs_usable_segs_in_sec(struct f2fs_sb_info *sbi, unsigned int f2fs_usable_blks_in_seg(struct f2fs_sb_info *sbi, unsigned int segno); +#define DEF_FRAGMENT_SIZE 4 +#define MIN_FRAGMENT_SIZE 1 +#define MAX_FRAGMENT_SIZE 512 + +static inline bool f2fs_need_rand_seg(struct f2fs_sb_info *sbi) +{ + return F2FS_OPTION(sbi).fs_mode == FS_MODE_FRAGMENT_SEG || + F2FS_OPTION(sbi).fs_mode == FS_MODE_FRAGMENT_RAND_BLK; +} + /* * checkpoint.c */ diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c index 2c18443972b6..72cfad99bbbe 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 diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c index a135d2247415..954c06728b94 100644 --- a/fs/f2fs/segment.c +++ b/fs/f2fs/segment.c @@ -15,6 +15,7 @@ #include #include #include +#include #include "f2fs.h" #include "segment.h" @@ -2630,6 +2631,8 @@ 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)) @@ -2681,6 +2684,11 @@ 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_FIXED_BLK) + curseg->fragment_remained_chunk = sbi->fragment_chunk_size; + else if (F2FS_OPTION(sbi).fs_mode == FS_MODE_FRAGMENT_RAND_BLK) + curseg->fragment_remained_chunk = + prandom_u32() % sbi->fragment_chunk_size + 1; } static int __next_free_blkoff(struct f2fs_sb_info *sbi, @@ -2707,12 +2715,29 @@ 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_FIXED_BLK) { + if (--seg->fragment_remained_chunk <= 0) { + seg->fragment_remained_chunk = + sbi->fragment_chunk_size; + seg->next_blkoff += + sbi->fragment_hole_size; + } + } else if (F2FS_OPTION(sbi).fs_mode == FS_MODE_FRAGMENT_RAND_BLK) { + /* To allocate block chunks in different sizes, use random number */ + if (--seg->fragment_remained_chunk <= 0) { + seg->fragment_remained_chunk = + prandom_u32() % sbi->fragment_chunk_size + 1; + seg->next_blkoff += + prandom_u32() % sbi->fragment_hole_size + 1; + } + } + } } bool f2fs_segment_has_free_slot(struct f2fs_sb_info *sbi, int segno) diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h index 89fff258727d..46fde9f3f28e 100644 --- a/fs/f2fs/segment.h +++ b/fs/f2fs/segment.h @@ -314,6 +314,7 @@ struct curseg_info { unsigned short next_blkoff; /* next block offset to write */ unsigned int zone; /* current zone number */ unsigned int next_segno; /* preallocated segment */ + int fragment_remained_chunk; /* remained block size in a chunk for block fragmentation mode */ bool inited; /* indicate inmem log is inited */ }; diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c index 49e153fd8183..60067b6d9fea 100644 --- a/fs/f2fs/super.c +++ b/fs/f2fs/super.c @@ -817,6 +817,12 @@ static int parse_options(struct super_block *sb, char *options, bool is_remount) F2FS_OPTION(sbi).fs_mode = FS_MODE_ADAPTIVE; } else if (!strcmp(name, "lfs")) { F2FS_OPTION(sbi).fs_mode = FS_MODE_LFS; + } else if (!strcmp(name, "fragment:segment")) { + F2FS_OPTION(sbi).fs_mode = FS_MODE_FRAGMENT_SEG; + } else if (!strcmp(name, "fragment:fixed_block")) { + F2FS_OPTION(sbi).fs_mode = FS_MODE_FRAGMENT_FIXED_BLK; + } else if (!strcmp(name, "fragment:rand_block")) { + F2FS_OPTION(sbi).fs_mode = FS_MODE_FRAGMENT_RAND_BLK; } else { kfree(name); return -EINVAL; @@ -1897,6 +1903,12 @@ static int f2fs_show_options(struct seq_file *seq, struct dentry *root) seq_puts(seq, "adaptive"); else if (F2FS_OPTION(sbi).fs_mode == FS_MODE_LFS) seq_puts(seq, "lfs"); + else if (F2FS_OPTION(sbi).fs_mode == FS_MODE_FRAGMENT_SEG) + seq_puts(seq, "fragment:segment"); + else if (F2FS_OPTION(sbi).fs_mode == FS_MODE_FRAGMENT_FIXED_BLK) + seq_puts(seq, "fragment:fixed_block"); + else if (F2FS_OPTION(sbi).fs_mode == FS_MODE_FRAGMENT_RAND_BLK) + seq_puts(seq, "fragment:rand_block"); seq_printf(seq, ",active_logs=%u", F2FS_OPTION(sbi).active_logs); if (test_opt(sbi, RESERVE_ROOT)) seq_printf(seq, ",reserve_root=%u,resuid=%u,resgid=%u", @@ -3515,6 +3527,8 @@ static void init_sb_info(struct f2fs_sb_info *sbi) sbi->max_victim_search = DEF_MAX_VICTIM_SEARCH; sbi->migration_granularity = sbi->segs_per_sec; sbi->seq_file_ra_mul = MIN_RA_MUL; + sbi->fragment_chunk_size = DEF_FRAGMENT_SIZE; + sbi->fragment_hole_size = DEF_FRAGMENT_SIZE; sbi->dir_level = DEF_DIR_LEVEL; sbi->interval_time[CP_TIME] = DEF_CP_INTERVAL; diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c index a1a3e0f6d658..ab34b3c2e09d 100644 --- a/fs/f2fs/sysfs.c +++ b/fs/f2fs/sysfs.c @@ -551,6 +551,22 @@ static ssize_t __sbi_store(struct f2fs_attr *a, return count; } + if (!strcmp(a->attr.name, "fragment_chunk_size")) { + if (t >= MIN_FRAGMENT_SIZE && t <= MAX_FRAGMENT_SIZE) + sbi->fragment_chunk_size = t; + else + return -EINVAL; + return count; + } + + if (!strcmp(a->attr.name, "fragment_hole_size")) { + if (t >= MIN_FRAGMENT_SIZE && t <= MAX_FRAGMENT_SIZE) + sbi->fragment_hole_size = t; + else + return -EINVAL; + return count; + } + *ui = (unsigned int)t; return count; @@ -781,6 +797,8 @@ F2FS_RW_ATTR(ATGC_INFO, atgc_management, atgc_age_threshold, age_threshold); F2FS_RW_ATTR(F2FS_SBI, f2fs_sb_info, seq_file_ra_mul, seq_file_ra_mul); F2FS_RW_ATTR(F2FS_SBI, f2fs_sb_info, gc_segment_mode, gc_segment_mode); F2FS_RW_ATTR(F2FS_SBI, f2fs_sb_info, gc_reclaimed_segments, gc_reclaimed_segs); +F2FS_RW_ATTR(F2FS_SBI, f2fs_sb_info, fragment_chunk_size, fragment_chunk_size); +F2FS_RW_ATTR(F2FS_SBI, f2fs_sb_info, fragment_hole_size, fragment_hole_size); #define ATTR_LIST(name) (&f2fs_attr_##name.attr) static struct attribute *f2fs_attrs[] = { @@ -859,6 +877,8 @@ static struct attribute *f2fs_attrs[] = { ATTR_LIST(seq_file_ra_mul), ATTR_LIST(gc_segment_mode), ATTR_LIST(gc_reclaimed_segments), + ATTR_LIST(fragment_chunk_size), + ATTR_LIST(fragment_hole_size), NULL, }; ATTRIBUTE_GROUPS(f2fs); -- 2.33.0.153.gba50c8fa24-goog