Suppose that the valid blocks of each section are all over sbi->fggc_threshold,
and even has_not_enough_free_secs is true, f2fs_gc cannot do its job since the
no_fggc_candidate always returns true. As a result, the reserved segments can be
used up, and finally there is no free segment at all, and get_new_segment cannot
get a free segment, filesystem will trap into a wrong status.
To fix this, we record the segno which has a rough minimum cost and return it to
__get_victim to continue f2fs_gc's job.
Signed-off-by: Yunlong Song <[email protected]>
---
fs/f2fs/gc.c | 19 ++++++++++++++-----
fs/f2fs/segment.h | 17 ++++++++++++++---
2 files changed, 28 insertions(+), 8 deletions(-)
diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
index fa3d2e2..965e783 100644
--- a/fs/f2fs/gc.c
+++ b/fs/f2fs/gc.c
@@ -178,6 +178,8 @@ static void select_policy(struct f2fs_sb_info *sbi, int gc_type,
p->offset = 0;
else
p->offset = SIT_I(sbi)->last_victim[p->gc_mode];
+
+ p->min_cost_r = UINT_MAX;
}
static unsigned int get_max_cost(struct f2fs_sb_info *sbi,
@@ -194,7 +196,7 @@ static unsigned int get_max_cost(struct f2fs_sb_info *sbi,
return 0;
}
-static unsigned int check_bg_victims(struct f2fs_sb_info *sbi)
+static unsigned int check_bg_victims(struct f2fs_sb_info *sbi, struct victim_sel_policy *p)
{
struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
unsigned int secno;
@@ -208,11 +210,12 @@ static unsigned int check_bg_victims(struct f2fs_sb_info *sbi)
if (sec_usage_check(sbi, secno))
continue;
- if (no_fggc_candidate(sbi, secno))
+ p->cur_segno_r = GET_SEG_FROM_SEC(sbi, secno);
+ if (no_fggc_candidate(sbi, secno, p))
continue;
clear_bit(secno, dirty_i->victim_secmap);
- return GET_SEG_FROM_SEC(sbi, secno);
+ return p->cur_segno_r;
}
return NULL_SEGNO;
}
@@ -332,7 +335,7 @@ static int get_victim_by_default(struct f2fs_sb_info *sbi,
last_victim = sm->last_victim[p.gc_mode];
if (p.alloc_mode == LFS && gc_type == FG_GC) {
- p.min_segno = check_bg_victims(sbi);
+ p.min_segno = check_bg_victims(sbi, &p);
if (p.min_segno != NULL_SEGNO)
goto got_it;
}
@@ -369,8 +372,9 @@ static int get_victim_by_default(struct f2fs_sb_info *sbi,
goto next;
if (gc_type == BG_GC && test_bit(secno, dirty_i->victim_secmap))
goto next;
+ p.cur_segno_r = segno;
if (gc_type == FG_GC && p.alloc_mode == LFS &&
- no_fggc_candidate(sbi, secno))
+ no_fggc_candidate(sbi, secno, &p))
goto next;
cost = get_gc_cost(sbi, segno, &p);
@@ -403,6 +407,11 @@ static int get_victim_by_default(struct f2fs_sb_info *sbi,
trace_f2fs_get_victim(sbi->sb, type, gc_type, &p,
sbi->cur_victim_sec,
prefree_segments(sbi), free_segments(sbi));
+ } else if (has_not_enough_free_secs(sbi, 0, 0)) {
+ p.min_segno = p.min_segno_r;
+ if (p.alloc_mode == LFS && gc_type == FG_GC)
+ clear_bit(GET_SEC_FROM_SEG(sbi, p.min_segno), dirty_i->victim_secmap);
+ goto got_it;
}
out:
mutex_unlock(&dirty_i->seglist_lock);
diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h
index 6b871b4..7d2d0f3 100644
--- a/fs/f2fs/segment.h
+++ b/fs/f2fs/segment.h
@@ -169,6 +169,9 @@ struct victim_sel_policy {
unsigned int ofs_unit; /* bitmap search unit */
unsigned int min_cost; /* minimum cost */
unsigned int min_segno; /* segment # having min. cost */
+ unsigned int min_cost_r; /* rough minimum cost */
+ unsigned int min_segno_r; /* segment # having rough min. cost */
+ unsigned int cur_segno_r; /* segment # rough process is handling */
};
struct seg_entry {
@@ -743,11 +746,19 @@ static inline block_t sum_blk_addr(struct f2fs_sb_info *sbi, int base, int type)
}
static inline bool no_fggc_candidate(struct f2fs_sb_info *sbi,
- unsigned int secno)
+ unsigned int secno, struct victim_sel_policy *p)
{
- if (get_valid_blocks(sbi, GET_SEG_FROM_SEC(sbi, secno), true) >=
- sbi->fggc_threshold)
+ unsigned int cur_cost;
+
+ cur_cost = get_valid_blocks(sbi, GET_SEG_FROM_SEC(sbi, secno), true);
+ if (cur_cost >= sbi->fggc_threshold) {
+ if (p->min_cost_r > cur_cost) {
+ p->min_cost_r = cur_cost;
+ p->min_segno_r = p->cur_segno_r;
+ }
return true;
+ }
+
return false;
}
--
1.8.5.2
Hi Yunlong,
On 07/14, Yunlong Song wrote:
> Suppose that the valid blocks of each section are all over sbi->fggc_threshold,
How about adding a kernel message first to detect your *supposed* sceanrio?
If that happens, it'll be a sort of bug which we haven't assumed.
Thanks,
> and even has_not_enough_free_secs is true, f2fs_gc cannot do its job since the
> no_fggc_candidate always returns true. As a result, the reserved segments can be
> used up, and finally there is no free segment at all, and get_new_segment cannot
> get a free segment, filesystem will trap into a wrong status.
>
> To fix this, we record the segno which has a rough minimum cost and return it to
> __get_victim to continue f2fs_gc's job.
>
> Signed-off-by: Yunlong Song <[email protected]>
> ---
> fs/f2fs/gc.c | 19 ++++++++++++++-----
> fs/f2fs/segment.h | 17 ++++++++++++++---
> 2 files changed, 28 insertions(+), 8 deletions(-)
>
> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
> index fa3d2e2..965e783 100644
> --- a/fs/f2fs/gc.c
> +++ b/fs/f2fs/gc.c
> @@ -178,6 +178,8 @@ static void select_policy(struct f2fs_sb_info *sbi, int gc_type,
> p->offset = 0;
> else
> p->offset = SIT_I(sbi)->last_victim[p->gc_mode];
> +
> + p->min_cost_r = UINT_MAX;
> }
>
> static unsigned int get_max_cost(struct f2fs_sb_info *sbi,
> @@ -194,7 +196,7 @@ static unsigned int get_max_cost(struct f2fs_sb_info *sbi,
> return 0;
> }
>
> -static unsigned int check_bg_victims(struct f2fs_sb_info *sbi)
> +static unsigned int check_bg_victims(struct f2fs_sb_info *sbi, struct victim_sel_policy *p)
> {
> struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
> unsigned int secno;
> @@ -208,11 +210,12 @@ static unsigned int check_bg_victims(struct f2fs_sb_info *sbi)
> if (sec_usage_check(sbi, secno))
> continue;
>
> - if (no_fggc_candidate(sbi, secno))
> + p->cur_segno_r = GET_SEG_FROM_SEC(sbi, secno);
> + if (no_fggc_candidate(sbi, secno, p))
> continue;
>
> clear_bit(secno, dirty_i->victim_secmap);
> - return GET_SEG_FROM_SEC(sbi, secno);
> + return p->cur_segno_r;
> }
> return NULL_SEGNO;
> }
> @@ -332,7 +335,7 @@ static int get_victim_by_default(struct f2fs_sb_info *sbi,
>
> last_victim = sm->last_victim[p.gc_mode];
> if (p.alloc_mode == LFS && gc_type == FG_GC) {
> - p.min_segno = check_bg_victims(sbi);
> + p.min_segno = check_bg_victims(sbi, &p);
> if (p.min_segno != NULL_SEGNO)
> goto got_it;
> }
> @@ -369,8 +372,9 @@ static int get_victim_by_default(struct f2fs_sb_info *sbi,
> goto next;
> if (gc_type == BG_GC && test_bit(secno, dirty_i->victim_secmap))
> goto next;
> + p.cur_segno_r = segno;
> if (gc_type == FG_GC && p.alloc_mode == LFS &&
> - no_fggc_candidate(sbi, secno))
> + no_fggc_candidate(sbi, secno, &p))
> goto next;
>
> cost = get_gc_cost(sbi, segno, &p);
> @@ -403,6 +407,11 @@ static int get_victim_by_default(struct f2fs_sb_info *sbi,
> trace_f2fs_get_victim(sbi->sb, type, gc_type, &p,
> sbi->cur_victim_sec,
> prefree_segments(sbi), free_segments(sbi));
> + } else if (has_not_enough_free_secs(sbi, 0, 0)) {
> + p.min_segno = p.min_segno_r;
> + if (p.alloc_mode == LFS && gc_type == FG_GC)
> + clear_bit(GET_SEC_FROM_SEG(sbi, p.min_segno), dirty_i->victim_secmap);
> + goto got_it;
> }
> out:
> mutex_unlock(&dirty_i->seglist_lock);
> diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h
> index 6b871b4..7d2d0f3 100644
> --- a/fs/f2fs/segment.h
> +++ b/fs/f2fs/segment.h
> @@ -169,6 +169,9 @@ struct victim_sel_policy {
> unsigned int ofs_unit; /* bitmap search unit */
> unsigned int min_cost; /* minimum cost */
> unsigned int min_segno; /* segment # having min. cost */
> + unsigned int min_cost_r; /* rough minimum cost */
> + unsigned int min_segno_r; /* segment # having rough min. cost */
> + unsigned int cur_segno_r; /* segment # rough process is handling */
> };
>
> struct seg_entry {
> @@ -743,11 +746,19 @@ static inline block_t sum_blk_addr(struct f2fs_sb_info *sbi, int base, int type)
> }
>
> static inline bool no_fggc_candidate(struct f2fs_sb_info *sbi,
> - unsigned int secno)
> + unsigned int secno, struct victim_sel_policy *p)
> {
> - if (get_valid_blocks(sbi, GET_SEG_FROM_SEC(sbi, secno), true) >=
> - sbi->fggc_threshold)
> + unsigned int cur_cost;
> +
> + cur_cost = get_valid_blocks(sbi, GET_SEG_FROM_SEC(sbi, secno), true);
> + if (cur_cost >= sbi->fggc_threshold) {
> + if (p->min_cost_r > cur_cost) {
> + p->min_cost_r = cur_cost;
> + p->min_segno_r = p->cur_segno_r;
> + }
> return true;
> + }
> +
> return false;
> }
>
> --
> 1.8.5.2
Hi Jay,
In fact，this is not "suppose" case yet, we have already met this problem several times in some test suits for corner case, or I cannot notice that this could happen.
On 2017/7/16 9:09, Jaegeuk Kim wrote:
> Hi Yunlong,
>
> On 07/14, Yunlong Song wrote:
>> Suppose that the valid blocks of each section are all over sbi->fggc_threshold,
> How about adding a kernel message first to detect your *supposed* sceanrio?
> If that happens, it'll be a sort of bug which we haven't assumed.
>
> Thanks,
>
>> and even has_not_enough_free_secs is true, f2fs_gc cannot do its job since the
>> no_fggc_candidate always returns true. As a result, the reserved segments can be
>> used up, and finally there is no free segment at all, and get_new_segment cannot
>> get a free segment, filesystem will trap into a wrong status.
>>
>> To fix this, we record the segno which has a rough minimum cost and return it to
>> __get_victim to continue f2fs_gc's job.
>>
>> Signed-off-by: Yunlong Song <[email protected]>
>> ---
>> fs/f2fs/gc.c | 19 ++++++++++++++-----
>> fs/f2fs/segment.h | 17 ++++++++++++++---
>> 2 files changed, 28 insertions(+), 8 deletions(-)
>>
>> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
>> index fa3d2e2..965e783 100644
>> --- a/fs/f2fs/gc.c
>> +++ b/fs/f2fs/gc.c
>> @@ -178,6 +178,8 @@ static void select_policy(struct f2fs_sb_info *sbi, int gc_type,
>> p->offset = 0;
>> else
>> p->offset = SIT_I(sbi)->last_victim[p->gc_mode];
>> +
>> + p->min_cost_r = UINT_MAX;
>> }
>>
>> static unsigned int get_max_cost(struct f2fs_sb_info *sbi,
>> @@ -194,7 +196,7 @@ static unsigned int get_max_cost(struct f2fs_sb_info *sbi,
>> return 0;
>> }
>>
>> -static unsigned int check_bg_victims(struct f2fs_sb_info *sbi)
>> +static unsigned int check_bg_victims(struct f2fs_sb_info *sbi, struct victim_sel_policy *p)
>> {
>> struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
>> unsigned int secno;
>> @@ -208,11 +210,12 @@ static unsigned int check_bg_victims(struct f2fs_sb_info *sbi)
>> if (sec_usage_check(sbi, secno))
>> continue;
>>
>> - if (no_fggc_candidate(sbi, secno))
>> + p->cur_segno_r = GET_SEG_FROM_SEC(sbi, secno);
>> + if (no_fggc_candidate(sbi, secno, p))
>> continue;
>>
>> clear_bit(secno, dirty_i->victim_secmap);
>> - return GET_SEG_FROM_SEC(sbi, secno);
>> + return p->cur_segno_r;
>> }
>> return NULL_SEGNO;
>> }
>> @@ -332,7 +335,7 @@ static int get_victim_by_default(struct f2fs_sb_info *sbi,
>>
>> last_victim = sm->last_victim[p.gc_mode];
>> if (p.alloc_mode == LFS && gc_type == FG_GC) {
>> - p.min_segno = check_bg_victims(sbi);
>> + p.min_segno = check_bg_victims(sbi, &p);
>> if (p.min_segno != NULL_SEGNO)
>> goto got_it;
>> }
>> @@ -369,8 +372,9 @@ static int get_victim_by_default(struct f2fs_sb_info *sbi,
>> goto next;
>> if (gc_type == BG_GC && test_bit(secno, dirty_i->victim_secmap))
>> goto next;
>> + p.cur_segno_r = segno;
>> if (gc_type == FG_GC && p.alloc_mode == LFS &&
>> - no_fggc_candidate(sbi, secno))
>> + no_fggc_candidate(sbi, secno, &p))
>> goto next;
>>
>> cost = get_gc_cost(sbi, segno, &p);
>> @@ -403,6 +407,11 @@ static int get_victim_by_default(struct f2fs_sb_info *sbi,
>> trace_f2fs_get_victim(sbi->sb, type, gc_type, &p,
>> sbi->cur_victim_sec,
>> prefree_segments(sbi), free_segments(sbi));
>> + } else if (has_not_enough_free_secs(sbi, 0, 0)) {
>> + p.min_segno = p.min_segno_r;
>> + if (p.alloc_mode == LFS && gc_type == FG_GC)
>> + clear_bit(GET_SEC_FROM_SEG(sbi, p.min_segno), dirty_i->victim_secmap);
>> + goto got_it;
>> }
>> out:
>> mutex_unlock(&dirty_i->seglist_lock);
>> diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h
>> index 6b871b4..7d2d0f3 100644
>> --- a/fs/f2fs/segment.h
>> +++ b/fs/f2fs/segment.h
>> @@ -169,6 +169,9 @@ struct victim_sel_policy {
>> unsigned int ofs_unit; /* bitmap search unit */
>> unsigned int min_cost; /* minimum cost */
>> unsigned int min_segno; /* segment # having min. cost */
>> + unsigned int min_cost_r; /* rough minimum cost */
>> + unsigned int min_segno_r; /* segment # having rough min. cost */
>> + unsigned int cur_segno_r; /* segment # rough process is handling */
>> };
>>
>> struct seg_entry {
>> @@ -743,11 +746,19 @@ static inline block_t sum_blk_addr(struct f2fs_sb_info *sbi, int base, int type)
>> }
>>
>> static inline bool no_fggc_candidate(struct f2fs_sb_info *sbi,
>> - unsigned int secno)
>> + unsigned int secno, struct victim_sel_policy *p)
>> {
>> - if (get_valid_blocks(sbi, GET_SEG_FROM_SEC(sbi, secno), true) >=
>> - sbi->fggc_threshold)
>> + unsigned int cur_cost;
>> +
>> + cur_cost = get_valid_blocks(sbi, GET_SEG_FROM_SEC(sbi, secno), true);
>> + if (cur_cost >= sbi->fggc_threshold) {
>> + if (p->min_cost_r > cur_cost) {
>> + p->min_cost_r = cur_cost;
>> + p->min_segno_r = p->cur_segno_r;
>> + }
>> return true;
>> + }
>> +
>> return false;
>> }
>>
>> --
>> 1.8.5.2
> .
>
--
Thanks,
Yunlong Song
On 07/16, sylinux wrote:
> In fact，this is not "suppose" case yet, we have already met this problem several times in some test suits for corner case, or I cannot notice that this could happen.
So, have you taken a look at distribution of valid blocks in that case?
I'm wondering what distribution can cause this.
Thanks,
>
>
>
>
> 发自网易邮箱大师
> On 07/16/2017 09:09, Jaegeuk Kim wrote:
> Hi Yunlong,
>
> On 07/14, Yunlong Song wrote:
> > Suppose that the valid blocks of each section are all over sbi->fggc_threshold,
>
> How about adding a kernel message first to detect your *supposed* sceanrio?
> If that happens, it'll be a sort of bug which we haven't assumed.
>
> Thanks,
>
> > and even has_not_enough_free_secs is true, f2fs_gc cannot do its job since the
> > no_fggc_candidate always returns true. As a result, the reserved segments can be
> > used up, and finally there is no free segment at all, and get_new_segment cannot
> > get a free segment, filesystem will trap into a wrong status.
> >
> > To fix this, we record the segno which has a rough minimum cost and return it to
> > __get_victim to continue f2fs_gc's job.
> >
> > Signed-off-by: Yunlong Song <[email protected]>
> > ---
> > fs/f2fs/gc.c | 19 ++++++++++++++-----
> > fs/f2fs/segment.h | 17 ++++++++++++++---
> > 2 files changed, 28 insertions(+), 8 deletions(-)
> >
> > diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
> > index fa3d2e2..965e783 100644
> > --- a/fs/f2fs/gc.c
> > +++ b/fs/f2fs/gc.c
> > @@ -178,6 +178,8 @@ static void select_policy(struct f2fs_sb_info *sbi, int gc_type,
> > p->offset = 0;
> > else
> > p->offset = SIT_I(sbi)->last_victim[p->gc_mode];
> > +
> > + p->min_cost_r = UINT_MAX;
> > }
> >
> > static unsigned int get_max_cost(struct f2fs_sb_info *sbi,
> > @@ -194,7 +196,7 @@ static unsigned int get_max_cost(struct f2fs_sb_info *sbi,
> > return 0;
> > }
> >
> > -static unsigned int check_bg_victims(struct f2fs_sb_info *sbi)
> > +static unsigned int check_bg_victims(struct f2fs_sb_info *sbi, struct victim_sel_policy *p)
> > {
> > struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
> > unsigned int secno;
> > @@ -208,11 +210,12 @@ static unsigned int check_bg_victims(struct f2fs_sb_info *sbi)
> > if (sec_usage_check(sbi, secno))
> > continue;
> >
> > - if (no_fggc_candidate(sbi, secno))
> > + p->cur_segno_r = GET_SEG_FROM_SEC(sbi, secno);
> > + if (no_fggc_candidate(sbi, secno, p))
> > continue;
> >
> > clear_bit(secno, dirty_i->victim_secmap);
> > - return GET_SEG_FROM_SEC(sbi, secno);
> > + return p->cur_segno_r;
> > }
> > return NULL_SEGNO;
> > }
> > @@ -332,7 +335,7 @@ static int get_victim_by_default(struct f2fs_sb_info *sbi,
> >
> > last_victim = sm->last_victim[p.gc_mode];
> > if (p.alloc_mode == LFS && gc_type == FG_GC) {
> > - p.min_segno = check_bg_victims(sbi);
> > + p.min_segno = check_bg_victims(sbi, &p);
> > if (p.min_segno != NULL_SEGNO)
> > goto got_it;
> > }
> > @@ -369,8 +372,9 @@ static int get_victim_by_default(struct f2fs_sb_info *sbi,
> > goto next;
> > if (gc_type == BG_GC && test_bit(secno, dirty_i->victim_secmap))
> > goto next;
> > + p.cur_segno_r = segno;
> > if (gc_type == FG_GC && p.alloc_mode == LFS &&
> > - no_fggc_candidate(sbi, secno))
> > + no_fggc_candidate(sbi, secno, &p))
> > goto next;
> >
> > cost = get_gc_cost(sbi, segno, &p);
> > @@ -403,6 +407,11 @@ static int get_victim_by_default(struct f2fs_sb_info *sbi,
> > trace_f2fs_get_victim(sbi->sb, type, gc_type, &p,
> > sbi->cur_victim_sec,
> > prefree_segments(sbi), free_segments(sbi));
> > + } else if (has_not_enough_free_secs(sbi, 0, 0)) {
> > + p.min_segno = p.min_segno_r;
> > + if (p.alloc_mode == LFS && gc_type == FG_GC)
> > + clear_bit(GET_SEC_FROM_SEG(sbi, p.min_segno), dirty_i->victim_secmap);
> > + goto got_it;
> > }
> > out:
> > mutex_unlock(&dirty_i->seglist_lock);
> > diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h
> > index 6b871b4..7d2d0f3 100644
> > --- a/fs/f2fs/segment.h
> > +++ b/fs/f2fs/segment.h
> > @@ -169,6 +169,9 @@ struct victim_sel_policy {
> > unsigned int ofs_unit; /* bitmap search unit */
> > unsigned int min_cost; /* minimum cost */
> > unsigned int min_segno; /* segment # having min. cost */
> > + unsigned int min_cost_r; /* rough minimum cost */
> > + unsigned int min_segno_r; /* segment # having rough min. cost */
> > + unsigned int cur_segno_r; /* segment # rough process is handling */
> > };
> >
> > struct seg_entry {
> > @@ -743,11 +746,19 @@ static inline block_t sum_blk_addr(struct f2fs_sb_info *sbi, int base, int type)
> > }
> >
> > static inline bool no_fggc_candidate(struct f2fs_sb_info *sbi,
> > - unsigned int secno)
> > + unsigned int secno, struct victim_sel_policy *p)
> > {
> > - if (get_valid_blocks(sbi, GET_SEG_FROM_SEC(sbi, secno), true) >=
> > - sbi->fggc_threshold)
> > + unsigned int cur_cost;
> > +
> > + cur_cost = get_valid_blocks(sbi, GET_SEG_FROM_SEC(sbi, secno), true);
> > + if (cur_cost >= sbi->fggc_threshold) {
> > + if (p->min_cost_r > cur_cost) {
> > + p->min_cost_r = cur_cost;
> > + p->min_segno_r = p->cur_segno_r;
> > + }
> > return true;
> > + }
> > +
> > return false;
> > }
> >
> > --
> > 1.8.5.2
Hi, Jay,
The distribution is like this, unit is segment counts:
cnt_free: 0 (free blocks)
cnt_full: 25182 (segment which has 512 blocks)
cnt_over: 25192 (segment which valid blocks over fggc_threshold)
cnt_below: 870 (segment which valid blocks below fggc_threshold)
The test is fragment test, add and delete small files over and over.
On 2017/7/18 0:56, Jaegeuk Kim wrote:
> On 07/16, sylinux wrote:
>> In fact，this is not "suppose" case yet, we have already met this problem several times in some test suits for corner case, or I cannot notice that this could happen.
> So, have you taken a look at distribution of valid blocks in that case?
> I'm wondering what distribution can cause this.
>
> Thanks,
>
>>
>>
>>
>> 发自网易邮箱大师
>> On 07/16/2017 09:09, Jaegeuk Kim wrote:
>> Hi Yunlong,
>>
>> On 07/14, Yunlong Song wrote:
>>> Suppose that the valid blocks of each section are all over sbi->fggc_threshold,
>> How about adding a kernel message first to detect your *supposed* sceanrio?
>> If that happens, it'll be a sort of bug which we haven't assumed.
>>
>> Thanks,
>>
>>> and even has_not_enough_free_secs is true, f2fs_gc cannot do its job since the
>>> no_fggc_candidate always returns true. As a result, the reserved segments can be
>>> used up, and finally there is no free segment at all, and get_new_segment cannot
>>> get a free segment, filesystem will trap into a wrong status.
>>>
>>> To fix this, we record the segno which has a rough minimum cost and return it to
>>> __get_victim to continue f2fs_gc's job.
>>>
>>> Signed-off-by: Yunlong Song <[email protected]>
>>> ---
>>> fs/f2fs/gc.c | 19 ++++++++++++++-----
>>> fs/f2fs/segment.h | 17 ++++++++++++++---
>>> 2 files changed, 28 insertions(+), 8 deletions(-)
>>>
>>> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
>>> index fa3d2e2..965e783 100644
>>> --- a/fs/f2fs/gc.c
>>> +++ b/fs/f2fs/gc.c
>>> @@ -178,6 +178,8 @@ static void select_policy(struct f2fs_sb_info *sbi, int gc_type,
>>> p->offset = 0;
>>> else
>>> p->offset = SIT_I(sbi)->last_victim[p->gc_mode];
>>> +
>>> + p->min_cost_r = UINT_MAX;
>>> }
>>>
>>> static unsigned int get_max_cost(struct f2fs_sb_info *sbi,
>>> @@ -194,7 +196,7 @@ static unsigned int get_max_cost(struct f2fs_sb_info *sbi,
>>> return 0;
>>> }
>>>
>>> -static unsigned int check_bg_victims(struct f2fs_sb_info *sbi)
>>> +static unsigned int check_bg_victims(struct f2fs_sb_info *sbi, struct victim_sel_policy *p)
>>> {
>>> struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
>>> unsigned int secno;
>>> @@ -208,11 +210,12 @@ static unsigned int check_bg_victims(struct f2fs_sb_info *sbi)
>>> if (sec_usage_check(sbi, secno))
>>> continue;
>>>
>>> - if (no_fggc_candidate(sbi, secno))
>>> + p->cur_segno_r = GET_SEG_FROM_SEC(sbi, secno);
>>> + if (no_fggc_candidate(sbi, secno, p))
>>> continue;
>>>
>>> clear_bit(secno, dirty_i->victim_secmap);
>>> - return GET_SEG_FROM_SEC(sbi, secno);
>>> + return p->cur_segno_r;
>>> }
>>> return NULL_SEGNO;
>>> }
>>> @@ -332,7 +335,7 @@ static int get_victim_by_default(struct f2fs_sb_info *sbi,
>>>
>>> last_victim = sm->last_victim[p.gc_mode];
>>> if (p.alloc_mode == LFS && gc_type == FG_GC) {
>>> - p.min_segno = check_bg_victims(sbi);
>>> + p.min_segno = check_bg_victims(sbi, &p);
>>> if (p.min_segno != NULL_SEGNO)
>>> goto got_it;
>>> }
>>> @@ -369,8 +372,9 @@ static int get_victim_by_default(struct f2fs_sb_info *sbi,
>>> goto next;
>>> if (gc_type == BG_GC && test_bit(secno, dirty_i->victim_secmap))
>>> goto next;
>>> + p.cur_segno_r = segno;
>>> if (gc_type == FG_GC && p.alloc_mode == LFS &&
>>> - no_fggc_candidate(sbi, secno))
>>> + no_fggc_candidate(sbi, secno, &p))
>>> goto next;
>>>
>>> cost = get_gc_cost(sbi, segno, &p);
>>> @@ -403,6 +407,11 @@ static int get_victim_by_default(struct f2fs_sb_info *sbi,
>>> trace_f2fs_get_victim(sbi->sb, type, gc_type, &p,
>>> sbi->cur_victim_sec,
>>> prefree_segments(sbi), free_segments(sbi));
>>> + } else if (has_not_enough_free_secs(sbi, 0, 0)) {
>>> + p.min_segno = p.min_segno_r;
>>> + if (p.alloc_mode == LFS && gc_type == FG_GC)
>>> + clear_bit(GET_SEC_FROM_SEG(sbi, p.min_segno), dirty_i->victim_secmap);
>>> + goto got_it;
>>> }
>>> out:
>>> mutex_unlock(&dirty_i->seglist_lock);
>>> diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h
>>> index 6b871b4..7d2d0f3 100644
>>> --- a/fs/f2fs/segment.h
>>> +++ b/fs/f2fs/segment.h
>>> @@ -169,6 +169,9 @@ struct victim_sel_policy {
>>> unsigned int ofs_unit; /* bitmap search unit */
>>> unsigned int min_cost; /* minimum cost */
>>> unsigned int min_segno; /* segment # having min. cost */
>>> + unsigned int min_cost_r; /* rough minimum cost */
>>> + unsigned int min_segno_r; /* segment # having rough min. cost */
>>> + unsigned int cur_segno_r; /* segment # rough process is handling */
>>> };
>>>
>>> struct seg_entry {
>>> @@ -743,11 +746,19 @@ static inline block_t sum_blk_addr(struct f2fs_sb_info *sbi, int base, int type)
>>> }
>>>
>>> static inline bool no_fggc_candidate(struct f2fs_sb_info *sbi,
>>> - unsigned int secno)
>>> + unsigned int secno, struct victim_sel_policy *p)
>>> {
>>> - if (get_valid_blocks(sbi, GET_SEG_FROM_SEC(sbi, secno), true) >=
>>> - sbi->fggc_threshold)
>>> + unsigned int cur_cost;
>>> +
>>> + cur_cost = get_valid_blocks(sbi, GET_SEG_FROM_SEC(sbi, secno), true);
>>> + if (cur_cost >= sbi->fggc_threshold) {
>>> + if (p->min_cost_r > cur_cost) {
>>> + p->min_cost_r = cur_cost;
>>> + p->min_segno_r = p->cur_segno_r;
>>> + }
>>> return true;
>>> + }
>>> +
>>> return false;
>>> }
>>>
>>> --
>>> 1.8.5.2
> .
>
--
Thanks,
Yunlong Song
Hi Yunlong,
On 07/20, Yunlong Song wrote:
> Hi, Jay,
> The distribution is like this, unit is segment counts:
> cnt_free: 0 (free blocks)
> cnt_full: 25182 (segment which has 512 blocks)
> cnt_over: 25192 (segment which valid blocks over fggc_threshold)
> cnt_below: 870 (segment which valid blocks below fggc_threshold)
What are the values of fggc_threshold and ovp ratio or reserved_segments?
How was the proc/segment_info?
Thanks,
>
> The test is fragment test, add and delete small files over and over.
>
> On 2017/7/18 0:56, Jaegeuk Kim wrote:
> > On 07/16, sylinux wrote:
> >> In fact，this is not "suppose" case yet, we have already met this problem several times in some test suits for corner case, or I cannot notice that this could happen.
> > So, have you taken a look at distribution of valid blocks in that case?
> > I'm wondering what distribution can cause this.
> >
> > Thanks,
> >
> >>
> >>
> >>
> >> 发自网易邮箱大师
> >> On 07/16/2017 09:09, Jaegeuk Kim wrote:
> >> Hi Yunlong,
> >>
> >> On 07/14, Yunlong Song wrote:
> >>> Suppose that the valid blocks of each section are all over sbi->fggc_threshold,
> >> How about adding a kernel message first to detect your *supposed* sceanrio?
> >> If that happens, it'll be a sort of bug which we haven't assumed.
> >>
> >> Thanks,
> >>
> >>> and even has_not_enough_free_secs is true, f2fs_gc cannot do its job since the
> >>> no_fggc_candidate always returns true. As a result, the reserved segments can be
> >>> used up, and finally there is no free segment at all, and get_new_segment cannot
> >>> get a free segment, filesystem will trap into a wrong status.
> >>>
> >>> To fix this, we record the segno which has a rough minimum cost and return it to
> >>> __get_victim to continue f2fs_gc's job.
> >>>
> >>> Signed-off-by: Yunlong Song <[email protected]>
> >>> ---
> >>> fs/f2fs/gc.c | 19 ++++++++++++++-----
> >>> fs/f2fs/segment.h | 17 ++++++++++++++---
> >>> 2 files changed, 28 insertions(+), 8 deletions(-)
> >>>
> >>> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
> >>> index fa3d2e2..965e783 100644
> >>> --- a/fs/f2fs/gc.c
> >>> +++ b/fs/f2fs/gc.c
> >>> @@ -178,6 +178,8 @@ static void select_policy(struct f2fs_sb_info *sbi, int gc_type,
> >>> p->offset = 0;
> >>> else
> >>> p->offset = SIT_I(sbi)->last_victim[p->gc_mode];
> >>> +
> >>> + p->min_cost_r = UINT_MAX;
> >>> }
> >>>
> >>> static unsigned int get_max_cost(struct f2fs_sb_info *sbi,
> >>> @@ -194,7 +196,7 @@ static unsigned int get_max_cost(struct f2fs_sb_info *sbi,
> >>> return 0;
> >>> }
> >>>
> >>> -static unsigned int check_bg_victims(struct f2fs_sb_info *sbi)
> >>> +static unsigned int check_bg_victims(struct f2fs_sb_info *sbi, struct victim_sel_policy *p)
> >>> {
> >>> struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
> >>> unsigned int secno;
> >>> @@ -208,11 +210,12 @@ static unsigned int check_bg_victims(struct f2fs_sb_info *sbi)
> >>> if (sec_usage_check(sbi, secno))
> >>> continue;
> >>>
> >>> - if (no_fggc_candidate(sbi, secno))
> >>> + p->cur_segno_r = GET_SEG_FROM_SEC(sbi, secno);
> >>> + if (no_fggc_candidate(sbi, secno, p))
> >>> continue;
> >>>
> >>> clear_bit(secno, dirty_i->victim_secmap);
> >>> - return GET_SEG_FROM_SEC(sbi, secno);
> >>> + return p->cur_segno_r;
> >>> }
> >>> return NULL_SEGNO;
> >>> }
> >>> @@ -332,7 +335,7 @@ static int get_victim_by_default(struct f2fs_sb_info *sbi,
> >>>
> >>> last_victim = sm->last_victim[p.gc_mode];
> >>> if (p.alloc_mode == LFS && gc_type == FG_GC) {
> >>> - p.min_segno = check_bg_victims(sbi);
> >>> + p.min_segno = check_bg_victims(sbi, &p);
> >>> if (p.min_segno != NULL_SEGNO)
> >>> goto got_it;
> >>> }
> >>> @@ -369,8 +372,9 @@ static int get_victim_by_default(struct f2fs_sb_info *sbi,
> >>> goto next;
> >>> if (gc_type == BG_GC && test_bit(secno, dirty_i->victim_secmap))
> >>> goto next;
> >>> + p.cur_segno_r = segno;
> >>> if (gc_type == FG_GC && p.alloc_mode == LFS &&
> >>> - no_fggc_candidate(sbi, secno))
> >>> + no_fggc_candidate(sbi, secno, &p))
> >>> goto next;
> >>>
> >>> cost = get_gc_cost(sbi, segno, &p);
> >>> @@ -403,6 +407,11 @@ static int get_victim_by_default(struct f2fs_sb_info *sbi,
> >>> trace_f2fs_get_victim(sbi->sb, type, gc_type, &p,
> >>> sbi->cur_victim_sec,
> >>> prefree_segments(sbi), free_segments(sbi));
> >>> + } else if (has_not_enough_free_secs(sbi, 0, 0)) {
> >>> + p.min_segno = p.min_segno_r;
> >>> + if (p.alloc_mode == LFS && gc_type == FG_GC)
> >>> + clear_bit(GET_SEC_FROM_SEG(sbi, p.min_segno), dirty_i->victim_secmap);
> >>> + goto got_it;
> >>> }
> >>> out:
> >>> mutex_unlock(&dirty_i->seglist_lock);
> >>> diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h
> >>> index 6b871b4..7d2d0f3 100644
> >>> --- a/fs/f2fs/segment.h
> >>> +++ b/fs/f2fs/segment.h
> >>> @@ -169,6 +169,9 @@ struct victim_sel_policy {
> >>> unsigned int ofs_unit; /* bitmap search unit */
> >>> unsigned int min_cost; /* minimum cost */
> >>> unsigned int min_segno; /* segment # having min. cost */
> >>> + unsigned int min_cost_r; /* rough minimum cost */
> >>> + unsigned int min_segno_r; /* segment # having rough min. cost */
> >>> + unsigned int cur_segno_r; /* segment # rough process is handling */
> >>> };
> >>>
> >>> struct seg_entry {
> >>> @@ -743,11 +746,19 @@ static inline block_t sum_blk_addr(struct f2fs_sb_info *sbi, int base, int type)
> >>> }
> >>>
> >>> static inline bool no_fggc_candidate(struct f2fs_sb_info *sbi,
> >>> - unsigned int secno)
> >>> + unsigned int secno, struct victim_sel_policy *p)
> >>> {
> >>> - if (get_valid_blocks(sbi, GET_SEG_FROM_SEC(sbi, secno), true) >=
> >>> - sbi->fggc_threshold)
> >>> + unsigned int cur_cost;
> >>> +
> >>> + cur_cost = get_valid_blocks(sbi, GET_SEG_FROM_SEC(sbi, secno), true);
> >>> + if (cur_cost >= sbi->fggc_threshold) {
> >>> + if (p->min_cost_r > cur_cost) {
> >>> + p->min_cost_r = cur_cost;
> >>> + p->min_segno_r = p->cur_segno_r;
> >>> + }
> >>> return true;
> >>> + }
> >>> +
> >>> return false;
> >>> }
> >>>
> >>> --
> >>> 1.8.5.2
> > .
> >
>
>
> --
> Thanks,
> Yunlong Song
>
Hi Jay,
fggc_threshold is 507, reserved_segment is 462.
On 2017/7/22 5:07, Jaegeuk Kim wrote:
> Hi Yunlong,
>
> On 07/20, Yunlong Song wrote:
>> Hi, Jay,
>> The distribution is like this, unit is segment counts:
>> cnt_free: 0 (free blocks)
>> cnt_full: 25182 (segment which has 512 blocks)
>> cnt_over: 25192 (segment which valid blocks over fggc_threshold)
>> cnt_below: 870 (segment which valid blocks below fggc_threshold)
> What are the values of fggc_threshold and ovp ratio or reserved_segments?
> How was the proc/segment_info?
>
> Thanks,
>
>> The test is fragment test, add and delete small files over and over.
>>
>> On 2017/7/18 0:56, Jaegeuk Kim wrote:
>>> On 07/16, sylinux wrote:
>>>> In fact，this is not "suppose" case yet, we have already met this problem several times in some test suits for corner case, or I cannot notice that this could happen.
>>> So, have you taken a look at distribution of valid blocks in that case?
>>> I'm wondering what distribution can cause this.
>>>
>>> Thanks,
>>>
>>>>
>>>>
>>>> 发自网易邮箱大师
>>>> On 07/16/2017 09:09, Jaegeuk Kim wrote:
>>>> Hi Yunlong,
>>>>
>>>> On 07/14, Yunlong Song wrote:
>>>>> Suppose that the valid blocks of each section are all over sbi->fggc_threshold,
>>>> How about adding a kernel message first to detect your *supposed* sceanrio?
>>>> If that happens, it'll be a sort of bug which we haven't assumed.
>>>>
>>>> Thanks,
>>>>
>>>>> and even has_not_enough_free_secs is true, f2fs_gc cannot do its job since the
>>>>> no_fggc_candidate always returns true. As a result, the reserved segments can be
>>>>> used up, and finally there is no free segment at all, and get_new_segment cannot
>>>>> get a free segment, filesystem will trap into a wrong status.
>>>>>
>>>>> To fix this, we record the segno which has a rough minimum cost and return it to
>>>>> __get_victim to continue f2fs_gc's job.
>>>>>
>>>>> Signed-off-by: Yunlong Song <[email protected]>
>>>>> ---
>>>>> fs/f2fs/gc.c | 19 ++++++++++++++-----
>>>>> fs/f2fs/segment.h | 17 ++++++++++++++---
>>>>> 2 files changed, 28 insertions(+), 8 deletions(-)
>>>>>
>>>>> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
>>>>> index fa3d2e2..965e783 100644
>>>>> --- a/fs/f2fs/gc.c
>>>>> +++ b/fs/f2fs/gc.c
>>>>> @@ -178,6 +178,8 @@ static void select_policy(struct f2fs_sb_info *sbi, int gc_type,
>>>>> p->offset = 0;
>>>>> else
>>>>> p->offset = SIT_I(sbi)->last_victim[p->gc_mode];
>>>>> +
>>>>> + p->min_cost_r = UINT_MAX;
>>>>> }
>>>>>
>>>>> static unsigned int get_max_cost(struct f2fs_sb_info *sbi,
>>>>> @@ -194,7 +196,7 @@ static unsigned int get_max_cost(struct f2fs_sb_info *sbi,
>>>>> return 0;
>>>>> }
>>>>>
>>>>> -static unsigned int check_bg_victims(struct f2fs_sb_info *sbi)
>>>>> +static unsigned int check_bg_victims(struct f2fs_sb_info *sbi, struct victim_sel_policy *p)
>>>>> {
>>>>> struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
>>>>> unsigned int secno;
>>>>> @@ -208,11 +210,12 @@ static unsigned int check_bg_victims(struct f2fs_sb_info *sbi)
>>>>> if (sec_usage_check(sbi, secno))
>>>>> continue;
>>>>>
>>>>> - if (no_fggc_candidate(sbi, secno))
>>>>> + p->cur_segno_r = GET_SEG_FROM_SEC(sbi, secno);
>>>>> + if (no_fggc_candidate(sbi, secno, p))
>>>>> continue;
>>>>>
>>>>> clear_bit(secno, dirty_i->victim_secmap);
>>>>> - return GET_SEG_FROM_SEC(sbi, secno);
>>>>> + return p->cur_segno_r;
>>>>> }
>>>>> return NULL_SEGNO;
>>>>> }
>>>>> @@ -332,7 +335,7 @@ static int get_victim_by_default(struct f2fs_sb_info *sbi,
>>>>>
>>>>> last_victim = sm->last_victim[p.gc_mode];
>>>>> if (p.alloc_mode == LFS && gc_type == FG_GC) {
>>>>> - p.min_segno = check_bg_victims(sbi);
>>>>> + p.min_segno = check_bg_victims(sbi, &p);
>>>>> if (p.min_segno != NULL_SEGNO)
>>>>> goto got_it;
>>>>> }
>>>>> @@ -369,8 +372,9 @@ static int get_victim_by_default(struct f2fs_sb_info *sbi,
>>>>> goto next;
>>>>> if (gc_type == BG_GC && test_bit(secno, dirty_i->victim_secmap))
>>>>> goto next;
>>>>> + p.cur_segno_r = segno;
>>>>> if (gc_type == FG_GC && p.alloc_mode == LFS &&
>>>>> - no_fggc_candidate(sbi, secno))
>>>>> + no_fggc_candidate(sbi, secno, &p))
>>>>> goto next;
>>>>>
>>>>> cost = get_gc_cost(sbi, segno, &p);
>>>>> @@ -403,6 +407,11 @@ static int get_victim_by_default(struct f2fs_sb_info *sbi,
>>>>> trace_f2fs_get_victim(sbi->sb, type, gc_type, &p,
>>>>> sbi->cur_victim_sec,
>>>>> prefree_segments(sbi), free_segments(sbi));
>>>>> + } else if (has_not_enough_free_secs(sbi, 0, 0)) {
>>>>> + p.min_segno = p.min_segno_r;
>>>>> + if (p.alloc_mode == LFS && gc_type == FG_GC)
>>>>> + clear_bit(GET_SEC_FROM_SEG(sbi, p.min_segno), dirty_i->victim_secmap);
>>>>> + goto got_it;
>>>>> }
>>>>> out:
>>>>> mutex_unlock(&dirty_i->seglist_lock);
>>>>> diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h
>>>>> index 6b871b4..7d2d0f3 100644
>>>>> --- a/fs/f2fs/segment.h
>>>>> +++ b/fs/f2fs/segment.h
>>>>> @@ -169,6 +169,9 @@ struct victim_sel_policy {
>>>>> unsigned int ofs_unit; /* bitmap search unit */
>>>>> unsigned int min_cost; /* minimum cost */
>>>>> unsigned int min_segno; /* segment # having min. cost */
>>>>> + unsigned int min_cost_r; /* rough minimum cost */
>>>>> + unsigned int min_segno_r; /* segment # having rough min. cost */
>>>>> + unsigned int cur_segno_r; /* segment # rough process is handling */
>>>>> };
>>>>>
>>>>> struct seg_entry {
>>>>> @@ -743,11 +746,19 @@ static inline block_t sum_blk_addr(struct f2fs_sb_info *sbi, int base, int type)
>>>>> }
>>>>>
>>>>> static inline bool no_fggc_candidate(struct f2fs_sb_info *sbi,
>>>>> - unsigned int secno)
>>>>> + unsigned int secno, struct victim_sel_policy *p)
>>>>> {
>>>>> - if (get_valid_blocks(sbi, GET_SEG_FROM_SEC(sbi, secno), true) >=
>>>>> - sbi->fggc_threshold)
>>>>> + unsigned int cur_cost;
>>>>> +
>>>>> + cur_cost = get_valid_blocks(sbi, GET_SEG_FROM_SEC(sbi, secno), true);
>>>>> + if (cur_cost >= sbi->fggc_threshold) {
>>>>> + if (p->min_cost_r > cur_cost) {
>>>>> + p->min_cost_r = cur_cost;
>>>>> + p->min_segno_r = p->cur_segno_r;
>>>>> + }
>>>>> return true;
>>>>> + }
>>>>> +
>>>>> return false;
>>>>> }
>>>>>
>>>>> --
>>>>> 1.8.5.2
>>> .
>>>
>>
>> --
>> Thanks,
>> Yunlong Song
>>
> .
>
--
Thanks,
Yunlong Song
On 07/14, Yunlong Song wrote:
> Suppose that the valid blocks of each section are all over sbi->fggc_threshold,
> and even has_not_enough_free_secs is true, f2fs_gc cannot do its job since the
> no_fggc_candidate always returns true. As a result, the reserved segments can be
> used up, and finally there is no free segment at all, and get_new_segment cannot
> get a free segment, filesystem will trap into a wrong status.
>
> To fix this, we record the segno which has a rough minimum cost and return it to
> __get_victim to continue f2fs_gc's job.
>
> Signed-off-by: Yunlong Song <[email protected]>
> ---
> fs/f2fs/gc.c | 19 ++++++++++++++-----
> fs/f2fs/segment.h | 17 ++++++++++++++---
> 2 files changed, 28 insertions(+), 8 deletions(-)
>
> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
> index fa3d2e2..965e783 100644
> --- a/fs/f2fs/gc.c
> +++ b/fs/f2fs/gc.c
> @@ -178,6 +178,8 @@ static void select_policy(struct f2fs_sb_info *sbi, int gc_type,
> p->offset = 0;
> else
> p->offset = SIT_I(sbi)->last_victim[p->gc_mode];
> +
> + p->min_cost_r = UINT_MAX;
> }
>
> static unsigned int get_max_cost(struct f2fs_sb_info *sbi,
> @@ -194,7 +196,7 @@ static unsigned int get_max_cost(struct f2fs_sb_info *sbi,
> return 0;
> }
>
> -static unsigned int check_bg_victims(struct f2fs_sb_info *sbi)
> +static unsigned int check_bg_victims(struct f2fs_sb_info *sbi, struct victim_sel_policy *p)
> {
> struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
> unsigned int secno;
> @@ -208,11 +210,12 @@ static unsigned int check_bg_victims(struct f2fs_sb_info *sbi)
> if (sec_usage_check(sbi, secno))
> continue;
>
> - if (no_fggc_candidate(sbi, secno))
> + p->cur_segno_r = GET_SEG_FROM_SEC(sbi, secno);
> + if (no_fggc_candidate(sbi, secno, p))
> continue;
>
> clear_bit(secno, dirty_i->victim_secmap);
> - return GET_SEG_FROM_SEC(sbi, secno);
> + return p->cur_segno_r;
> }
> return NULL_SEGNO;
> }
> @@ -332,7 +335,7 @@ static int get_victim_by_default(struct f2fs_sb_info *sbi,
>
> last_victim = sm->last_victim[p.gc_mode];
> if (p.alloc_mode == LFS && gc_type == FG_GC) {
> - p.min_segno = check_bg_victims(sbi);
> + p.min_segno = check_bg_victims(sbi, &p);
> if (p.min_segno != NULL_SEGNO)
> goto got_it;
> }
> @@ -369,8 +372,9 @@ static int get_victim_by_default(struct f2fs_sb_info *sbi,
> goto next;
> if (gc_type == BG_GC && test_bit(secno, dirty_i->victim_secmap))
> goto next;
> + p.cur_segno_r = segno;
> if (gc_type == FG_GC && p.alloc_mode == LFS &&
> - no_fggc_candidate(sbi, secno))
> + no_fggc_candidate(sbi, secno, &p))
> goto next;
>
> cost = get_gc_cost(sbi, segno, &p);
> @@ -403,6 +407,11 @@ static int get_victim_by_default(struct f2fs_sb_info *sbi,
> trace_f2fs_get_victim(sbi->sb, type, gc_type, &p,
> sbi->cur_victim_sec,
> prefree_segments(sbi), free_segments(sbi));
> + } else if (has_not_enough_free_secs(sbi, 0, 0)) {
> + p.min_segno = p.min_segno_r;
> + if (p.alloc_mode == LFS && gc_type == FG_GC)
> + clear_bit(GET_SEC_FROM_SEG(sbi, p.min_segno), dirty_i->victim_secmap);
It seems you want to give a victim segment which has valid blocks larger than
fggc_threshold.
fggc: 507
reserve: 462
cnt_full: 25182
over: 25912 (>= fggc)
less: 870 (< fggc)
What is ovp segments?
It looks like there are 870 candidates for FG_GC, and GC with 103 segments must
give 104 free segments in the worst case. Is there a problem on p.max_search?
Thanks,
> + goto got_it;
> }
> out:
> mutex_unlock(&dirty_i->seglist_lock);
> diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h
> index 6b871b4..7d2d0f3 100644
> --- a/fs/f2fs/segment.h
> +++ b/fs/f2fs/segment.h
> @@ -169,6 +169,9 @@ struct victim_sel_policy {
> unsigned int ofs_unit; /* bitmap search unit */
> unsigned int min_cost; /* minimum cost */
> unsigned int min_segno; /* segment # having min. cost */
> + unsigned int min_cost_r; /* rough minimum cost */
> + unsigned int min_segno_r; /* segment # having rough min. cost */
> + unsigned int cur_segno_r; /* segment # rough process is handling */
> };
>
> struct seg_entry {
> @@ -743,11 +746,19 @@ static inline block_t sum_blk_addr(struct f2fs_sb_info *sbi, int base, int type)
> }
>
> static inline bool no_fggc_candidate(struct f2fs_sb_info *sbi,
> - unsigned int secno)
> + unsigned int secno, struct victim_sel_policy *p)
> {
> - if (get_valid_blocks(sbi, GET_SEG_FROM_SEC(sbi, secno), true) >=
> - sbi->fggc_threshold)
> + unsigned int cur_cost;
> +
> + cur_cost = get_valid_blocks(sbi, GET_SEG_FROM_SEC(sbi, secno), true);
> + if (cur_cost >= sbi->fggc_threshold) {
> + if (p->min_cost_r > cur_cost) {
> + p->min_cost_r = cur_cost;
> + p->min_segno_r = p->cur_segno_r;
> + }
> return true;
> + }
> +
> return false;
> }
>
> --
> 1.8.5.2
Hi, Jay,
Sorry for the mistake in last mail, the ovp is 462, and the reserved is 235.
I check the code and have not found problems with p.max_search yet.
Just forget the this patch, since there is still 870 segments below, so
it should
not be the assumed case of this patch.
By the way, I have sent another patch to provide f2fs_balance_fs to
__write_node_page,
similar as that in __write_data_page, to avoid missing f2fs_balance_fs
in node page writeback.
Please check that.
On 2017/7/26 2:55, Jaegeuk Kim wrote:
> On 07/14, Yunlong Song wrote:
>> Suppose that the valid blocks of each section are all over sbi->fggc_threshold,
>> and even has_not_enough_free_secs is true, f2fs_gc cannot do its job since the
>> no_fggc_candidate always returns true. As a result, the reserved segments can be
>> used up, and finally there is no free segment at all, and get_new_segment cannot
>> get a free segment, filesystem will trap into a wrong status.
>>
>> To fix this, we record the segno which has a rough minimum cost and return it to
>> __get_victim to continue f2fs_gc's job.
>>
>> Signed-off-by: Yunlong Song <[email protected]>
>> ---
>> fs/f2fs/gc.c | 19 ++++++++++++++-----
>> fs/f2fs/segment.h | 17 ++++++++++++++---
>> 2 files changed, 28 insertions(+), 8 deletions(-)
>>
>> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
>> index fa3d2e2..965e783 100644
>> --- a/fs/f2fs/gc.c
>> +++ b/fs/f2fs/gc.c
>> @@ -178,6 +178,8 @@ static void select_policy(struct f2fs_sb_info *sbi, int gc_type,
>> p->offset = 0;
>> else
>> p->offset = SIT_I(sbi)->last_victim[p->gc_mode];
>> +
>> + p->min_cost_r = UINT_MAX;
>> }
>>
>> static unsigned int get_max_cost(struct f2fs_sb_info *sbi,
>> @@ -194,7 +196,7 @@ static unsigned int get_max_cost(struct f2fs_sb_info *sbi,
>> return 0;
>> }
>>
>> -static unsigned int check_bg_victims(struct f2fs_sb_info *sbi)
>> +static unsigned int check_bg_victims(struct f2fs_sb_info *sbi, struct victim_sel_policy *p)
>> {
>> struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
>> unsigned int secno;
>> @@ -208,11 +210,12 @@ static unsigned int check_bg_victims(struct f2fs_sb_info *sbi)
>> if (sec_usage_check(sbi, secno))
>> continue;
>>
>> - if (no_fggc_candidate(sbi, secno))
>> + p->cur_segno_r = GET_SEG_FROM_SEC(sbi, secno);
>> + if (no_fggc_candidate(sbi, secno, p))
>> continue;
>>
>> clear_bit(secno, dirty_i->victim_secmap);
>> - return GET_SEG_FROM_SEC(sbi, secno);
>> + return p->cur_segno_r;
>> }
>> return NULL_SEGNO;
>> }
>> @@ -332,7 +335,7 @@ static int get_victim_by_default(struct f2fs_sb_info *sbi,
>>
>> last_victim = sm->last_victim[p.gc_mode];
>> if (p.alloc_mode == LFS && gc_type == FG_GC) {
>> - p.min_segno = check_bg_victims(sbi);
>> + p.min_segno = check_bg_victims(sbi, &p);
>> if (p.min_segno != NULL_SEGNO)
>> goto got_it;
>> }
>> @@ -369,8 +372,9 @@ static int get_victim_by_default(struct f2fs_sb_info *sbi,
>> goto next;
>> if (gc_type == BG_GC && test_bit(secno, dirty_i->victim_secmap))
>> goto next;
>> + p.cur_segno_r = segno;
>> if (gc_type == FG_GC && p.alloc_mode == LFS &&
>> - no_fggc_candidate(sbi, secno))
>> + no_fggc_candidate(sbi, secno, &p))
>> goto next;
>>
>> cost = get_gc_cost(sbi, segno, &p);
>> @@ -403,6 +407,11 @@ static int get_victim_by_default(struct f2fs_sb_info *sbi,
>> trace_f2fs_get_victim(sbi->sb, type, gc_type, &p,
>> sbi->cur_victim_sec,
>> prefree_segments(sbi), free_segments(sbi));
>> + } else if (has_not_enough_free_secs(sbi, 0, 0)) {
>> + p.min_segno = p.min_segno_r;
>> + if (p.alloc_mode == LFS && gc_type == FG_GC)
>> + clear_bit(GET_SEC_FROM_SEG(sbi, p.min_segno), dirty_i->victim_secmap);
> It seems you want to give a victim segment which has valid blocks larger than
> fggc_threshold.
>
> fggc: 507
> reserve: 462
> cnt_full: 25182
> over: 25912 (>= fggc)
> less: 870 (< fggc)
>
> What is ovp segments?
> It looks like there are 870 candidates for FG_GC, and GC with 103 segments must
> give 104 free segments in the worst case. Is there a problem on p.max_search?
>
> Thanks,
>
>> + goto got_it;
>> }
>> out:
>> mutex_unlock(&dirty_i->seglist_lock);
>> diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h
>> index 6b871b4..7d2d0f3 100644
>> --- a/fs/f2fs/segment.h
>> +++ b/fs/f2fs/segment.h
>> @@ -169,6 +169,9 @@ struct victim_sel_policy {
>> unsigned int ofs_unit; /* bitmap search unit */
>> unsigned int min_cost; /* minimum cost */
>> unsigned int min_segno; /* segment # having min. cost */
>> + unsigned int min_cost_r; /* rough minimum cost */
>> + unsigned int min_segno_r; /* segment # having rough min. cost */
>> + unsigned int cur_segno_r; /* segment # rough process is handling */
>> };
>>
>> struct seg_entry {
>> @@ -743,11 +746,19 @@ static inline block_t sum_blk_addr(struct f2fs_sb_info *sbi, int base, int type)
>> }
>>
>> static inline bool no_fggc_candidate(struct f2fs_sb_info *sbi,
>> - unsigned int secno)
>> + unsigned int secno, struct victim_sel_policy *p)
>> {
>> - if (get_valid_blocks(sbi, GET_SEG_FROM_SEC(sbi, secno), true) >=
>> - sbi->fggc_threshold)
>> + unsigned int cur_cost;
>> +
>> + cur_cost = get_valid_blocks(sbi, GET_SEG_FROM_SEC(sbi, secno), true);
>> + if (cur_cost >= sbi->fggc_threshold) {
>> + if (p->min_cost_r > cur_cost) {
>> + p->min_cost_r = cur_cost;
>> + p->min_segno_r = p->cur_segno_r;
>> + }
>> return true;
>> + }
>> +
>> return false;
>> }
>>
>> --
>> 1.8.5.2
> .
>
--
Thanks,
Yunlong Song