[PATCH 3/5] f2fs: retry gc if one section is not successfully reclaimed

From: Jaegeuk Kim
Date: Tue Aug 18 2015 - 04:47:56 EST


If FG_GC failed to reclaim one section, let's retry with another section
from the start, since we can get anoterh good candidate.

Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
---
fs/f2fs/gc.c | 42 +++++++++++++++++++-----------------------
1 file changed, 19 insertions(+), 23 deletions(-)

diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
index 0a5d573..c40dda3 100644
--- a/fs/f2fs/gc.c
+++ b/fs/f2fs/gc.c
@@ -391,7 +391,7 @@ static int check_valid_map(struct f2fs_sb_info *sbi,
* On validity, copy that node with cold status, otherwise (invalid node)
* ignore that.
*/
-static void gc_node_segment(struct f2fs_sb_info *sbi,
+static int gc_node_segment(struct f2fs_sb_info *sbi,
struct f2fs_summary *sum, unsigned int segno, int gc_type)
{
bool initial = true;
@@ -411,7 +411,7 @@ next_step:

/* stop BG_GC if there is not enough free sections. */
if (gc_type == BG_GC && has_not_enough_free_secs(sbi, 0))
- return;
+ return 0;

if (check_valid_map(sbi, segno, off) == 0)
continue;
@@ -461,13 +461,11 @@ next_step:
};
sync_node_pages(sbi, 0, &wbc);

- /*
- * In the case of FG_GC, it'd be better to reclaim this victim
- * completely.
- */
- if (get_valid_blocks(sbi, segno, 1) != 0)
- goto next_step;
+ /* return 1 only if FG_GC succefully reclaimed one */
+ if (get_valid_blocks(sbi, segno, 1) == 0)
+ return 1;
}
+ return 0;
}

/*
@@ -649,7 +647,7 @@ out:
* If the parent node is not valid or the data block address is different,
* the victim data block is ignored.
*/
-static void gc_data_segment(struct f2fs_sb_info *sbi, struct f2fs_summary *sum,
+static int gc_data_segment(struct f2fs_sb_info *sbi, struct f2fs_summary *sum,
struct gc_inode_list *gc_list, unsigned int segno, int gc_type)
{
struct super_block *sb = sbi->sb;
@@ -672,7 +670,7 @@ next_step:

/* stop BG_GC if there is not enough free sections. */
if (gc_type == BG_GC && has_not_enough_free_secs(sbi, 0))
- return;
+ return 0;

if (check_valid_map(sbi, segno, off) == 0)
continue;
@@ -737,15 +735,11 @@ next_step:
if (gc_type == FG_GC) {
f2fs_submit_merged_bio(sbi, DATA, WRITE);

- /*
- * In the case of FG_GC, it'd be better to reclaim this victim
- * completely.
- */
- if (get_valid_blocks(sbi, segno, 1) != 0) {
- phase = 2;
- goto next_step;
- }
+ /* return 1 only if FG_GC succefully reclaimed one */
+ if (get_valid_blocks(sbi, segno, 1) == 0)
+ return 1;
}
+ return 0;
}

static int __get_victim(struct f2fs_sb_info *sbi, unsigned int *victim,
@@ -761,12 +755,13 @@ static int __get_victim(struct f2fs_sb_info *sbi, unsigned int *victim,
return ret;
}

-static void do_garbage_collect(struct f2fs_sb_info *sbi, unsigned int segno,
+static int do_garbage_collect(struct f2fs_sb_info *sbi, unsigned int segno,
struct gc_inode_list *gc_list, int gc_type)
{
struct page *sum_page;
struct f2fs_summary_block *sum;
struct blk_plug plug;
+ int nfree = 0;

/* read segment summary of victim */
sum_page = get_sum_page(sbi, segno);
@@ -786,10 +781,11 @@ static void do_garbage_collect(struct f2fs_sb_info *sbi, unsigned int segno,

switch (GET_SUM_TYPE((&sum->footer))) {
case SUM_TYPE_NODE:
- gc_node_segment(sbi, sum->entries, segno, gc_type);
+ nfree = gc_node_segment(sbi, sum->entries, segno, gc_type);
break;
case SUM_TYPE_DATA:
- gc_data_segment(sbi, sum->entries, gc_list, segno, gc_type);
+ nfree = gc_data_segment(sbi, sum->entries, gc_list,
+ segno, gc_type);
break;
}
blk_finish_plug(&plug);
@@ -798,6 +794,7 @@ static void do_garbage_collect(struct f2fs_sb_info *sbi, unsigned int segno,
stat_inc_call_count(sbi->stat_info);

f2fs_put_page(sum_page, 0);
+ return nfree;
}

int f2fs_gc(struct f2fs_sb_info *sbi)
@@ -836,11 +833,10 @@ gc_more:
META_SSA);

for (i = 0; i < sbi->segs_per_sec; i++)
- do_garbage_collect(sbi, segno + i, &gc_list, gc_type);
+ nfree += do_garbage_collect(sbi, segno + i, &gc_list, gc_type);

if (gc_type == FG_GC) {
sbi->cur_victim_sec = NULL_SEGNO;
- nfree++;
WARN_ON(get_valid_blocks(sbi, segno, sbi->segs_per_sec));
}

--
2.1.1

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