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f2fs: reclaim prefree segments periodically

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Previously, f2fs postpones reclaiming prefree segments into free segments
as much as possible.
However, if user writes and deletes a bunch of data without any sync or fsync
calls, some flash storages can suffer from garbage collections.

So, this patch adds the reclaiming codes to f2fs_write_node_pages and background
GC thread.

If there are a lot of prefree segments, let's do checkpoint so that f2fs
submits discard commands for the prefree regions to the flash storage.

Signed-off-by: Changman Lee <cm224.lee@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
This commit is contained in:
Jaegeuk Kim 2013-10-24 13:31:34 +09:00
parent aabe51364f
commit 81eb8d6e28
5 changed files with 18 additions and 1 deletions
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3
fs/f2fs/f2fs.h
View file

@ -299,6 +299,9 @@ struct f2fs_sm_info {
unsigned int main_segments; /* # of segments in main area */ unsigned int main_segments; /* # of segments in main area */
unsigned int reserved_segments; /* # of reserved segments */ unsigned int reserved_segments; /* # of reserved segments */
unsigned int ovp_segments; /* # of overprovision segments */ unsigned int ovp_segments; /* # of overprovision segments */
/* a threshold to reclaim prefree segments */
unsigned int rec_prefree_segments;
}; };
/* /*

5
fs/f2fs/gc.c
View file

@ -82,6 +82,11 @@ static int gc_thread_func(void *data)
/* if return value is not zero, no victim was selected */ /* if return value is not zero, no victim was selected */
if (f2fs_gc(sbi)) if (f2fs_gc(sbi))
wait_ms = gc_th->no_gc_sleep_time; wait_ms = gc_th->no_gc_sleep_time;
/* balancing prefree segments */
if (excess_prefree_segs(sbi))
f2fs_sync_fs(sbi->sb, true);
} while (!kthread_should_stop()); } while (!kthread_should_stop());
return 0; return 0;
} }

3
fs/f2fs/node.c
View file

@ -1206,7 +1206,8 @@ static int f2fs_write_node_pages(struct address_space *mapping,
long nr_to_write = wbc->nr_to_write; long nr_to_write = wbc->nr_to_write;
/* First check balancing cached NAT entries */ /* First check balancing cached NAT entries */
if (try_to_free_nats(sbi, NAT_ENTRY_PER_BLOCK)) { if (try_to_free_nats(sbi, NAT_ENTRY_PER_BLOCK) ||
excess_prefree_segs(sbi)) {
f2fs_sync_fs(sbi->sb, true); f2fs_sync_fs(sbi->sb, true);
return 0; return 0;
} }

1
fs/f2fs/segment.c
View file

@ -1645,6 +1645,7 @@ int build_segment_manager(struct f2fs_sb_info *sbi)
sm_info->ovp_segments = le32_to_cpu(ckpt->overprov_segment_count); sm_info->ovp_segments = le32_to_cpu(ckpt->overprov_segment_count);
sm_info->main_segments = le32_to_cpu(raw_super->segment_count_main); sm_info->main_segments = le32_to_cpu(raw_super->segment_count_main);
sm_info->ssa_blkaddr = le32_to_cpu(raw_super->ssa_blkaddr); sm_info->ssa_blkaddr = le32_to_cpu(raw_super->ssa_blkaddr);
sm_info->rec_prefree_segments = DEF_RECLAIM_PREFREE_SEGMENTS;
err = build_sit_info(sbi); err = build_sit_info(sbi);
if (err) if (err)

7
fs/f2fs/segment.h
View file

@ -14,6 +14,8 @@
#define NULL_SEGNO ((unsigned int)(~0)) #define NULL_SEGNO ((unsigned int)(~0))
#define NULL_SECNO ((unsigned int)(~0)) #define NULL_SECNO ((unsigned int)(~0))
#define DEF_RECLAIM_PREFREE_SEGMENTS 100 /* 200MB of prefree segments */
/* L: Logical segment # in volume, R: Relative segment # in main area */ /* L: Logical segment # in volume, R: Relative segment # in main area */
#define GET_L2R_SEGNO(free_i, segno) (segno - free_i->start_segno) #define GET_L2R_SEGNO(free_i, segno) (segno - free_i->start_segno)
#define GET_R2L_SEGNO(free_i, segno) (segno + free_i->start_segno) #define GET_R2L_SEGNO(free_i, segno) (segno + free_i->start_segno)
@ -472,6 +474,11 @@ static inline bool has_not_enough_free_secs(struct f2fs_sb_info *sbi, int freed)
reserved_sections(sbi))); reserved_sections(sbi)));
} }
static inline bool excess_prefree_segs(struct f2fs_sb_info *sbi)
{
return (prefree_segments(sbi) > SM_I(sbi)->rec_prefree_segments);
}
static inline int utilization(struct f2fs_sb_info *sbi) static inline int utilization(struct f2fs_sb_info *sbi)
{ {
return div_u64((u64)valid_user_blocks(sbi) * 100, sbi->user_block_count); return div_u64((u64)valid_user_blocks(sbi) * 100, sbi->user_block_count);