Re: [PATCH v4] f2fs: fix to avoid race during access gc_thread pointer
On 2018/5/8 5:36, Jaegeuk Kim wrote:
> On 05/07, Chao Yu wrote:
>> Thread A Thread BThread C
>> - f2fs_remount
>> - stop_gc_thread
>> - f2fs_sbi_store
>> - issue_discard_thread
>>sbi->gc_thread = NULL;
>>sbi->gc_thread->gc_wake = 1
>>access
>> sbi->gc_thread->gc_urgent
>>
>> Previously, we allocate memory for sbi->gc_thread based on background
>> gc thread mount option, the memory can be released if we turn off
>> that mount option, but still there are several places access gc_thread
>> pointer without considering race condition, result in NULL point
>> dereference.
>>
>> In order to fix this issue, introduce gc_rwsem to exclude those operations.
>>
>> Signed-off-by: Chao Yu
>> ---
>> v4:
>> - use introduced sbi.gc_rwsem lock instead of sb.s_umount.
>
> We can use this first.
>
>>From e62e8d3ece6ee8a4aeac8ffd6161d25851f8b3f0 Mon Sep 17 00:00:00 2001
> From: Jaegeuk Kim
> Date: Mon, 7 May 2018 14:22:40 -0700
> Subject: [PATCH] f2fs: introduce sbi->gc_mode to determine the policy
>
> This is to avoid sbi->gc_thread pointer access.
>
> Signed-off-by: Jaegeuk Kim
> ---
> fs/f2fs/f2fs.h| 8
> fs/f2fs/gc.c | 28
> fs/f2fs/gc.h | 2 --
> fs/f2fs/segment.c | 4 ++--
> fs/f2fs/sysfs.c | 33 +
> 5 files changed, 47 insertions(+), 28 deletions(-)
>
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index 80490a7991a7..779d8b26878c 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -1065,6 +1065,13 @@ enum {
> MAX_TIME,
> };
>
> +enum {
> + GC_NORMAL,
> + GC_IDLE_CB,
> + GC_IDLE_GREEDY,
> + GC_URGENT,
> +};
> +
> enum {
> WHINT_MODE_OFF, /* not pass down write hints */
> WHINT_MODE_USER,/* try to pass down hints given by users */
> @@ -1193,6 +1200,7 @@ struct f2fs_sb_info {
> struct mutex gc_mutex; /* mutex for GC */
> struct f2fs_gc_kthread *gc_thread; /* GC thread */
> unsigned int cur_victim_sec;/* current victim section num */
> + unsigned int gc_mode; /* current GC state */
>
> /* threshold for gc trials on pinned files */
> u64 gc_pin_file_threshold;
> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
> index 9bb2ddbbed1e..7ec8ea75dfde 100644
> --- a/fs/f2fs/gc.c
> +++ b/fs/f2fs/gc.c
> @@ -76,7 +76,7 @@ static int gc_thread_func(void *data)
>* invalidated soon after by user update or deletion.
>* So, I'd like to wait some time to collect dirty segments.
>*/
> - if (gc_th->gc_urgent) {
> + if (sbi->gc_mode == GC_URGENT) {
> wait_ms = gc_th->urgent_sleep_time;
> mutex_lock(&sbi->gc_mutex);
> goto do_gc;
> @@ -131,8 +131,6 @@ int start_gc_thread(struct f2fs_sb_info *sbi)
> gc_th->max_sleep_time = DEF_GC_THREAD_MAX_SLEEP_TIME;
> gc_th->no_gc_sleep_time = DEF_GC_THREAD_NOGC_SLEEP_TIME;
>
> - gc_th->gc_idle = 0;
> - gc_th->gc_urgent = 0;
> gc_th->gc_wake= 0;
>
> sbi->gc_thread = gc_th;
> @@ -158,21 +156,19 @@ void stop_gc_thread(struct f2fs_sb_info *sbi)
> sbi->gc_thread = NULL;
> }
>
> -static int select_gc_type(struct f2fs_gc_kthread *gc_th, int gc_type)
> +static int select_gc_type(struct f2fs_sb_info *sbi, int gc_type)
> {
> int gc_mode = (gc_type == BG_GC) ? GC_CB : GC_GREEDY;
>
> - if (!gc_th)
> - return gc_mode;
> -
> - if (gc_th->gc_idle) {
> - if (gc_th->gc_idle == 1)
> - gc_mode = GC_CB;
> - else if (gc_th->gc_idle == 2)
> - gc_mode = GC_GREEDY;
> - }
> - if (gc_th->gc_urgent)
> + switch (sbi->gc_mode) {
> + case GC_IDLE_CB:
> + gc_mode = GC_CB;
> + break;
> + case GC_IDLE_GREEDY:
> + case GC_URGENT:
> gc_mode = GC_GREEDY;
> + break;
> + }
> return gc_mode;
> }
>
> @@ -187,7 +183,7 @@ static void select_policy(struct f2fs_sb_info *sbi, int
> gc_type,
> p->max_search = dirty_i->nr_dirty[type];
> p->ofs_unit = 1;
> } else {
> - p->gc_mode = select_gc_type(sbi->gc_thread, gc_type);
> + p->gc_mode = select_gc_type(sbi, gc_type);
> p->dirty_segmap = dirty_i->dirty_segmap[DIRTY];
> p->max_search = dirty_i->nr_dirty[DIRTY];
> p->ofs_unit = sbi->segs_per_sec;
> @@ -195,7 +191,7 @@ static void select_policy(struct f2fs_sb_info *sbi, int
> gc_type,
>
> /* we need to check every dirty segments in the FG_GC case */
> if (gc_type != FG_GC &&
> - (sbi->gc_thread && !sbi->gc_thread->gc_urgent)
Re: [PATCH v4] f2fs: fix to avoid race during access gc_thread pointer
On 2018/5/8 11:17, Jaegeuk Kim wrote:
> On 05/08, Chao Yu wrote:
>> On 2018/5/8 5:36, Jaegeuk Kim wrote:
>>> On 05/07, Chao Yu wrote:
Thread A Thread BThread C
- f2fs_remount
- stop_gc_thread
- f2fs_sbi_store
- issue_discard_thread
sbi->gc_thread = NULL;
sbi->gc_thread->gc_wake = 1
access
sbi->gc_thread->gc_urgent
Previously, we allocate memory for sbi->gc_thread based on background
gc thread mount option, the memory can be released if we turn off
that mount option, but still there are several places access gc_thread
pointer without considering race condition, result in NULL point
dereference.
In order to fix this issue, introduce gc_rwsem to exclude those operations.
Signed-off-by: Chao Yu
---
v4:
- use introduced sbi.gc_rwsem lock instead of sb.s_umount.
>>>
>>> We can use this first.
>>>
>>> >From e62e8d3ece6ee8a4aeac8ffd6161d25851f8b3f0 Mon Sep 17 00:00:00 2001
>>> From: Jaegeuk Kim
>>> Date: Mon, 7 May 2018 14:22:40 -0700
>>> Subject: [PATCH] f2fs: introduce sbi->gc_mode to determine the policy
>>>
>>> This is to avoid sbi->gc_thread pointer access.
>>>
>>> Signed-off-by: Jaegeuk Kim
>>> ---
>>> fs/f2fs/f2fs.h| 8
>>> fs/f2fs/gc.c | 28
>>> fs/f2fs/gc.h | 2 --
>>> fs/f2fs/segment.c | 4 ++--
>>> fs/f2fs/sysfs.c | 33 +
>>> 5 files changed, 47 insertions(+), 28 deletions(-)
>>>
>>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
>>> index 80490a7991a7..779d8b26878c 100644
>>> --- a/fs/f2fs/f2fs.h
>>> +++ b/fs/f2fs/f2fs.h
>>> @@ -1065,6 +1065,13 @@ enum {
>>> MAX_TIME,
>>> };
>>>
>>> +enum {
>>> + GC_NORMAL,
>>> + GC_IDLE_CB,
>>> + GC_IDLE_GREEDY,
>>> + GC_URGENT,
>>> +};
>>> +
>>> enum {
>>> WHINT_MODE_OFF, /* not pass down write hints */
>>> WHINT_MODE_USER,/* try to pass down hints given by users */
>>> @@ -1193,6 +1200,7 @@ struct f2fs_sb_info {
>>> struct mutex gc_mutex; /* mutex for GC */
>>> struct f2fs_gc_kthread *gc_thread; /* GC thread */
>>> unsigned int cur_victim_sec;/* current victim section num */
>>> + unsigned int gc_mode; /* current GC state */
>>>
>>> /* threshold for gc trials on pinned files */
>>> u64 gc_pin_file_threshold;
>>> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
>>> index 9bb2ddbbed1e..7ec8ea75dfde 100644
>>> --- a/fs/f2fs/gc.c
>>> +++ b/fs/f2fs/gc.c
>>> @@ -76,7 +76,7 @@ static int gc_thread_func(void *data)
>>> * invalidated soon after by user update or deletion.
>>> * So, I'd like to wait some time to collect dirty segments.
>>> */
>>> - if (gc_th->gc_urgent) {
>>> + if (sbi->gc_mode == GC_URGENT) {
>>> wait_ms = gc_th->urgent_sleep_time;
>>> mutex_lock(&sbi->gc_mutex);
>>> goto do_gc;
>>> @@ -131,8 +131,6 @@ int start_gc_thread(struct f2fs_sb_info *sbi)
>>> gc_th->max_sleep_time = DEF_GC_THREAD_MAX_SLEEP_TIME;
>>> gc_th->no_gc_sleep_time = DEF_GC_THREAD_NOGC_SLEEP_TIME;
>>>
>>> - gc_th->gc_idle = 0;
>>> - gc_th->gc_urgent = 0;
>>> gc_th->gc_wake= 0;
>>>
>>> sbi->gc_thread = gc_th;
>>> @@ -158,21 +156,19 @@ void stop_gc_thread(struct f2fs_sb_info *sbi)
>>> sbi->gc_thread = NULL;
>>> }
>>>
>>> -static int select_gc_type(struct f2fs_gc_kthread *gc_th, int gc_type)
>>> +static int select_gc_type(struct f2fs_sb_info *sbi, int gc_type)
>>> {
>>> int gc_mode = (gc_type == BG_GC) ? GC_CB : GC_GREEDY;
>>>
>>> - if (!gc_th)
>>> - return gc_mode;
>>> -
>>> - if (gc_th->gc_idle) {
>>> - if (gc_th->gc_idle == 1)
>>> - gc_mode = GC_CB;
>>> - else if (gc_th->gc_idle == 2)
>>> - gc_mode = GC_GREEDY;
>>> - }
>>> - if (gc_th->gc_urgent)
>>> + switch (sbi->gc_mode) {
>>> + case GC_IDLE_CB:
>>> + gc_mode = GC_CB;
>>> + break;
>>> + case GC_IDLE_GREEDY:
>>> + case GC_URGENT:
>>> gc_mode = GC_GREEDY;
>>> + break;
>>> + }
>>> return gc_mode;
>>> }
>>>
>>> @@ -187,7 +183,7 @@ static void select_policy(struct f2fs_sb_info *sbi, int
>>> gc_type,
>>> p->max_search = dirty_i->nr_dirty[type];
>>> p->ofs_unit = 1;
>>> } else {
>>> - p->gc_mode = select_gc_type(sbi->gc_thread, gc_type);
>>> + p->gc_mode = select_gc_type(sbi, gc_type);
>>> p->dirty_segmap = dirty_i->dirty_segmap[DIRTY];
>>> p->max_search = dirty_i->nr_dirty[DIRTY];
>>> p->ofs_unit = sbi->segs_per_sec;
>>> @@ -195,7 +191,7 @@ static void select_policy(struct f2fs_
Re: [PATCH v4] f2fs: fix to avoid race during access gc_thread pointer
On 05/08, Chao Yu wrote:
> On 2018/5/8 5:36, Jaegeuk Kim wrote:
> > On 05/07, Chao Yu wrote:
> >> Thread A Thread BThread C
> >> - f2fs_remount
> >> - stop_gc_thread
> >>- f2fs_sbi_store
> >>- issue_discard_thread
> >>sbi->gc_thread = NULL;
> >> sbi->gc_thread->gc_wake = 1
> >> access
> >> sbi->gc_thread->gc_urgent
> >>
> >> Previously, we allocate memory for sbi->gc_thread based on background
> >> gc thread mount option, the memory can be released if we turn off
> >> that mount option, but still there are several places access gc_thread
> >> pointer without considering race condition, result in NULL point
> >> dereference.
> >>
> >> In order to fix this issue, introduce gc_rwsem to exclude those operations.
> >>
> >> Signed-off-by: Chao Yu
> >> ---
> >> v4:
> >> - use introduced sbi.gc_rwsem lock instead of sb.s_umount.
> >
> > We can use this first.
> >
> >>From e62e8d3ece6ee8a4aeac8ffd6161d25851f8b3f0 Mon Sep 17 00:00:00 2001
> > From: Jaegeuk Kim
> > Date: Mon, 7 May 2018 14:22:40 -0700
> > Subject: [PATCH] f2fs: introduce sbi->gc_mode to determine the policy
> >
> > This is to avoid sbi->gc_thread pointer access.
> >
> > Signed-off-by: Jaegeuk Kim
> > ---
> > fs/f2fs/f2fs.h| 8
> > fs/f2fs/gc.c | 28
> > fs/f2fs/gc.h | 2 --
> > fs/f2fs/segment.c | 4 ++--
> > fs/f2fs/sysfs.c | 33 +
> > 5 files changed, 47 insertions(+), 28 deletions(-)
> >
> > diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> > index 80490a7991a7..779d8b26878c 100644
> > --- a/fs/f2fs/f2fs.h
> > +++ b/fs/f2fs/f2fs.h
> > @@ -1065,6 +1065,13 @@ enum {
> > MAX_TIME,
> > };
> >
> > +enum {
> > + GC_NORMAL,
> > + GC_IDLE_CB,
> > + GC_IDLE_GREEDY,
> > + GC_URGENT,
> > +};
> > +
> > enum {
> > WHINT_MODE_OFF, /* not pass down write hints */
> > WHINT_MODE_USER,/* try to pass down hints given by users */
> > @@ -1193,6 +1200,7 @@ struct f2fs_sb_info {
> > struct mutex gc_mutex; /* mutex for GC */
> > struct f2fs_gc_kthread *gc_thread; /* GC thread */
> > unsigned int cur_victim_sec;/* current victim section num */
> > + unsigned int gc_mode; /* current GC state */
> >
> > /* threshold for gc trials on pinned files */
> > u64 gc_pin_file_threshold;
> > diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
> > index 9bb2ddbbed1e..7ec8ea75dfde 100644
> > --- a/fs/f2fs/gc.c
> > +++ b/fs/f2fs/gc.c
> > @@ -76,7 +76,7 @@ static int gc_thread_func(void *data)
> > * invalidated soon after by user update or deletion.
> > * So, I'd like to wait some time to collect dirty segments.
> > */
> > - if (gc_th->gc_urgent) {
> > + if (sbi->gc_mode == GC_URGENT) {
> > wait_ms = gc_th->urgent_sleep_time;
> > mutex_lock(&sbi->gc_mutex);
> > goto do_gc;
> > @@ -131,8 +131,6 @@ int start_gc_thread(struct f2fs_sb_info *sbi)
> > gc_th->max_sleep_time = DEF_GC_THREAD_MAX_SLEEP_TIME;
> > gc_th->no_gc_sleep_time = DEF_GC_THREAD_NOGC_SLEEP_TIME;
> >
> > - gc_th->gc_idle = 0;
> > - gc_th->gc_urgent = 0;
> > gc_th->gc_wake= 0;
> >
> > sbi->gc_thread = gc_th;
> > @@ -158,21 +156,19 @@ void stop_gc_thread(struct f2fs_sb_info *sbi)
> > sbi->gc_thread = NULL;
> > }
> >
> > -static int select_gc_type(struct f2fs_gc_kthread *gc_th, int gc_type)
> > +static int select_gc_type(struct f2fs_sb_info *sbi, int gc_type)
> > {
> > int gc_mode = (gc_type == BG_GC) ? GC_CB : GC_GREEDY;
> >
> > - if (!gc_th)
> > - return gc_mode;
> > -
> > - if (gc_th->gc_idle) {
> > - if (gc_th->gc_idle == 1)
> > - gc_mode = GC_CB;
> > - else if (gc_th->gc_idle == 2)
> > - gc_mode = GC_GREEDY;
> > - }
> > - if (gc_th->gc_urgent)
> > + switch (sbi->gc_mode) {
> > + case GC_IDLE_CB:
> > + gc_mode = GC_CB;
> > + break;
> > + case GC_IDLE_GREEDY:
> > + case GC_URGENT:
> > gc_mode = GC_GREEDY;
> > + break;
> > + }
> > return gc_mode;
> > }
> >
> > @@ -187,7 +183,7 @@ static void select_policy(struct f2fs_sb_info *sbi, int
> > gc_type,
> > p->max_search = dirty_i->nr_dirty[type];
> > p->ofs_unit = 1;
> > } else {
> > - p->gc_mode = select_gc_type(sbi->gc_thread, gc_type);
> > + p->gc_mode = select_gc_type(sbi, gc_type);
> > p->dirty_segmap = dirty_i->dirty_segmap[DIRTY];
> > p->max_search = dirty_i->nr_dirty[DIRTY];
> > p->ofs_unit = sbi->segs_per_sec;
> > @@ -195,7 +191,7 @@ static void select_policy(struct f2fs_sb_info *sbi, int
> > gc_type,
> >
Re: [PATCH v4] f2fs: fix to avoid race during access gc_thread pointer
On 2018/5/8 5:36, Jaegeuk Kim wrote:
> On 05/07, Chao Yu wrote:
>> Thread A Thread BThread C
>> - f2fs_remount
>> - stop_gc_thread
>> - f2fs_sbi_store
>> - issue_discard_thread
>>sbi->gc_thread = NULL;
>>sbi->gc_thread->gc_wake = 1
>>access
>> sbi->gc_thread->gc_urgent
>>
>> Previously, we allocate memory for sbi->gc_thread based on background
>> gc thread mount option, the memory can be released if we turn off
>> that mount option, but still there are several places access gc_thread
>> pointer without considering race condition, result in NULL point
>> dereference.
>>
>> In order to fix this issue, introduce gc_rwsem to exclude those operations.
>>
>> Signed-off-by: Chao Yu
>> ---
>> v4:
>> - use introduced sbi.gc_rwsem lock instead of sb.s_umount.
>
> We can use this first.
>
>>From e62e8d3ece6ee8a4aeac8ffd6161d25851f8b3f0 Mon Sep 17 00:00:00 2001
> From: Jaegeuk Kim
> Date: Mon, 7 May 2018 14:22:40 -0700
> Subject: [PATCH] f2fs: introduce sbi->gc_mode to determine the policy
>
> This is to avoid sbi->gc_thread pointer access.
>
> Signed-off-by: Jaegeuk Kim
> ---
> fs/f2fs/f2fs.h| 8
> fs/f2fs/gc.c | 28
> fs/f2fs/gc.h | 2 --
> fs/f2fs/segment.c | 4 ++--
> fs/f2fs/sysfs.c | 33 +
> 5 files changed, 47 insertions(+), 28 deletions(-)
>
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index 80490a7991a7..779d8b26878c 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -1065,6 +1065,13 @@ enum {
> MAX_TIME,
> };
>
> +enum {
> + GC_NORMAL,
> + GC_IDLE_CB,
> + GC_IDLE_GREEDY,
> + GC_URGENT,
> +};
> +
> enum {
> WHINT_MODE_OFF, /* not pass down write hints */
> WHINT_MODE_USER,/* try to pass down hints given by users */
> @@ -1193,6 +1200,7 @@ struct f2fs_sb_info {
> struct mutex gc_mutex; /* mutex for GC */
> struct f2fs_gc_kthread *gc_thread; /* GC thread */
> unsigned int cur_victim_sec;/* current victim section num */
> + unsigned int gc_mode; /* current GC state */
>
> /* threshold for gc trials on pinned files */
> u64 gc_pin_file_threshold;
> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
> index 9bb2ddbbed1e..7ec8ea75dfde 100644
> --- a/fs/f2fs/gc.c
> +++ b/fs/f2fs/gc.c
> @@ -76,7 +76,7 @@ static int gc_thread_func(void *data)
>* invalidated soon after by user update or deletion.
>* So, I'd like to wait some time to collect dirty segments.
>*/
> - if (gc_th->gc_urgent) {
> + if (sbi->gc_mode == GC_URGENT) {
> wait_ms = gc_th->urgent_sleep_time;
> mutex_lock(&sbi->gc_mutex);
> goto do_gc;
> @@ -131,8 +131,6 @@ int start_gc_thread(struct f2fs_sb_info *sbi)
> gc_th->max_sleep_time = DEF_GC_THREAD_MAX_SLEEP_TIME;
> gc_th->no_gc_sleep_time = DEF_GC_THREAD_NOGC_SLEEP_TIME;
>
> - gc_th->gc_idle = 0;
> - gc_th->gc_urgent = 0;
> gc_th->gc_wake= 0;
>
> sbi->gc_thread = gc_th;
> @@ -158,21 +156,19 @@ void stop_gc_thread(struct f2fs_sb_info *sbi)
> sbi->gc_thread = NULL;
> }
>
> -static int select_gc_type(struct f2fs_gc_kthread *gc_th, int gc_type)
> +static int select_gc_type(struct f2fs_sb_info *sbi, int gc_type)
> {
> int gc_mode = (gc_type == BG_GC) ? GC_CB : GC_GREEDY;
>
> - if (!gc_th)
> - return gc_mode;
> -
> - if (gc_th->gc_idle) {
> - if (gc_th->gc_idle == 1)
> - gc_mode = GC_CB;
> - else if (gc_th->gc_idle == 2)
> - gc_mode = GC_GREEDY;
> - }
> - if (gc_th->gc_urgent)
> + switch (sbi->gc_mode) {
> + case GC_IDLE_CB:
> + gc_mode = GC_CB;
> + break;
> + case GC_IDLE_GREEDY:
> + case GC_URGENT:
> gc_mode = GC_GREEDY;
> + break;
> + }
> return gc_mode;
> }
>
> @@ -187,7 +183,7 @@ static void select_policy(struct f2fs_sb_info *sbi, int
> gc_type,
> p->max_search = dirty_i->nr_dirty[type];
> p->ofs_unit = 1;
> } else {
> - p->gc_mode = select_gc_type(sbi->gc_thread, gc_type);
> + p->gc_mode = select_gc_type(sbi, gc_type);
> p->dirty_segmap = dirty_i->dirty_segmap[DIRTY];
> p->max_search = dirty_i->nr_dirty[DIRTY];
> p->ofs_unit = sbi->segs_per_sec;
> @@ -195,7 +191,7 @@ static void select_policy(struct f2fs_sb_info *sbi, int
> gc_type,
>
> /* we need to check every dirty segments in the FG_GC case */
> if (gc_type != FG_GC &&
> - (sbi->gc_thread && !sbi->gc_thread->gc_urgent)
Re: [PATCH v4] f2fs: fix to avoid race during access gc_thread pointer
On 05/07, Chao Yu wrote:
> Thread A Thread BThread C
> - f2fs_remount
> - stop_gc_thread
> - f2fs_sbi_store
> - issue_discard_thread
>sbi->gc_thread = NULL;
> sbi->gc_thread->gc_wake = 1
> access
> sbi->gc_thread->gc_urgent
>
> Previously, we allocate memory for sbi->gc_thread based on background
> gc thread mount option, the memory can be released if we turn off
> that mount option, but still there are several places access gc_thread
> pointer without considering race condition, result in NULL point
> dereference.
>
> In order to fix this issue, introduce gc_rwsem to exclude those operations.
>
> Signed-off-by: Chao Yu
> ---
> v4:
> - use introduced sbi.gc_rwsem lock instead of sb.s_umount.
We can use this first.
>From e62e8d3ece6ee8a4aeac8ffd6161d25851f8b3f0 Mon Sep 17 00:00:00 2001
From: Jaegeuk Kim
Date: Mon, 7 May 2018 14:22:40 -0700
Subject: [PATCH] f2fs: introduce sbi->gc_mode to determine the policy
This is to avoid sbi->gc_thread pointer access.
Signed-off-by: Jaegeuk Kim
---
fs/f2fs/f2fs.h| 8
fs/f2fs/gc.c | 28
fs/f2fs/gc.h | 2 --
fs/f2fs/segment.c | 4 ++--
fs/f2fs/sysfs.c | 33 +
5 files changed, 47 insertions(+), 28 deletions(-)
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 80490a7991a7..779d8b26878c 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -1065,6 +1065,13 @@ enum {
MAX_TIME,
};
+enum {
+ GC_NORMAL,
+ GC_IDLE_CB,
+ GC_IDLE_GREEDY,
+ GC_URGENT,
+};
+
enum {
WHINT_MODE_OFF, /* not pass down write hints */
WHINT_MODE_USER,/* try to pass down hints given by users */
@@ -1193,6 +1200,7 @@ struct f2fs_sb_info {
struct mutex gc_mutex; /* mutex for GC */
struct f2fs_gc_kthread *gc_thread; /* GC thread */
unsigned int cur_victim_sec;/* current victim section num */
+ unsigned int gc_mode; /* current GC state */
/* threshold for gc trials on pinned files */
u64 gc_pin_file_threshold;
diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
index 9bb2ddbbed1e..7ec8ea75dfde 100644
--- a/fs/f2fs/gc.c
+++ b/fs/f2fs/gc.c
@@ -76,7 +76,7 @@ static int gc_thread_func(void *data)
* invalidated soon after by user update or deletion.
* So, I'd like to wait some time to collect dirty segments.
*/
- if (gc_th->gc_urgent) {
+ if (sbi->gc_mode == GC_URGENT) {
wait_ms = gc_th->urgent_sleep_time;
mutex_lock(&sbi->gc_mutex);
goto do_gc;
@@ -131,8 +131,6 @@ int start_gc_thread(struct f2fs_sb_info *sbi)
gc_th->max_sleep_time = DEF_GC_THREAD_MAX_SLEEP_TIME;
gc_th->no_gc_sleep_time = DEF_GC_THREAD_NOGC_SLEEP_TIME;
- gc_th->gc_idle = 0;
- gc_th->gc_urgent = 0;
gc_th->gc_wake= 0;
sbi->gc_thread = gc_th;
@@ -158,21 +156,19 @@ void stop_gc_thread(struct f2fs_sb_info *sbi)
sbi->gc_thread = NULL;
}
-static int select_gc_type(struct f2fs_gc_kthread *gc_th, int gc_type)
+static int select_gc_type(struct f2fs_sb_info *sbi, int gc_type)
{
int gc_mode = (gc_type == BG_GC) ? GC_CB : GC_GREEDY;
- if (!gc_th)
- return gc_mode;
-
- if (gc_th->gc_idle) {
- if (gc_th->gc_idle == 1)
- gc_mode = GC_CB;
- else if (gc_th->gc_idle == 2)
- gc_mode = GC_GREEDY;
- }
- if (gc_th->gc_urgent)
+ switch (sbi->gc_mode) {
+ case GC_IDLE_CB:
+ gc_mode = GC_CB;
+ break;
+ case GC_IDLE_GREEDY:
+ case GC_URGENT:
gc_mode = GC_GREEDY;
+ break;
+ }
return gc_mode;
}
@@ -187,7 +183,7 @@ static void select_policy(struct f2fs_sb_info *sbi, int
gc_type,
p->max_search = dirty_i->nr_dirty[type];
p->ofs_unit = 1;
} else {
- p->gc_mode = select_gc_type(sbi->gc_thread, gc_type);
+ p->gc_mode = select_gc_type(sbi, gc_type);
p->dirty_segmap = dirty_i->dirty_segmap[DIRTY];
p->max_search = dirty_i->nr_dirty[DIRTY];
p->ofs_unit = sbi->segs_per_sec;
@@ -195,7 +191,7 @@ static void select_policy(struct f2fs_sb_info *sbi, int
gc_type,
/* we need to check every dirty segments in the FG_GC case */
if (gc_type != FG_GC &&
- (sbi->gc_thread && !sbi->gc_thread->gc_urgent) &&
+ (sbi->gc_mode != GC_URGENT) &&
p->max_search > sbi->max_victim_search)
p->max_search = sbi->ma
[PATCH v4] f2fs: fix to avoid race during access gc_thread pointer
Thread AThread BThread C
- f2fs_remount
- stop_gc_thread
- f2fs_sbi_store
- issue_discard_thread
sbi->gc_thread = NULL;
sbi->gc_thread->gc_wake = 1
access
sbi->gc_thread->gc_urgent
Previously, we allocate memory for sbi->gc_thread based on background
gc thread mount option, the memory can be released if we turn off
that mount option, but still there are several places access gc_thread
pointer without considering race condition, result in NULL point
dereference.
In order to fix this issue, introduce gc_rwsem to exclude those operations.
Signed-off-by: Chao Yu
---
v4:
- use introduced sbi.gc_rwsem lock instead of sb.s_umount.
fs/f2fs/f2fs.h| 1 +
fs/f2fs/gc.c | 4
fs/f2fs/segment.c | 11 ++-
fs/f2fs/super.c | 19 ++-
fs/f2fs/sysfs.c | 14 +++---
5 files changed, 40 insertions(+), 9 deletions(-)
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 80490a7991a7..e238d0ea0be7 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -1191,6 +1191,7 @@ struct f2fs_sb_info {
/* for cleaning operations */
struct mutex gc_mutex; /* mutex for GC */
+ struct rw_semaphore gc_rwsem; /* rw semaphore for gc_thread */
struct f2fs_gc_kthread *gc_thread; /* GC thread */
unsigned int cur_victim_sec;/* current victim section num */
diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
index 9bb2ddbbed1e..b74714be7be7 100644
--- a/fs/f2fs/gc.c
+++ b/fs/f2fs/gc.c
@@ -187,17 +187,21 @@ static void select_policy(struct f2fs_sb_info *sbi, int
gc_type,
p->max_search = dirty_i->nr_dirty[type];
p->ofs_unit = 1;
} else {
+ down_read(&sbi->gc_rwsem);
p->gc_mode = select_gc_type(sbi->gc_thread, gc_type);
+ up_read(&sbi->gc_rwsem);
p->dirty_segmap = dirty_i->dirty_segmap[DIRTY];
p->max_search = dirty_i->nr_dirty[DIRTY];
p->ofs_unit = sbi->segs_per_sec;
}
/* we need to check every dirty segments in the FG_GC case */
+ down_read(&sbi->gc_rwsem);
if (gc_type != FG_GC &&
(sbi->gc_thread && !sbi->gc_thread->gc_urgent) &&
p->max_search > sbi->max_victim_search)
p->max_search = sbi->max_victim_search;
+ up_read(&sbi->gc_rwsem);
/* let's select beginning hot/small space first in no_heap mode*/
if (test_opt(sbi, NOHEAP) &&
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 320cc1c57246..33d146939048 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -174,11 +174,18 @@ bool need_SSR(struct f2fs_sb_info *sbi)
int node_secs = get_blocktype_secs(sbi, F2FS_DIRTY_NODES);
int dent_secs = get_blocktype_secs(sbi, F2FS_DIRTY_DENTS);
int imeta_secs = get_blocktype_secs(sbi, F2FS_DIRTY_IMETA);
+ bool gc_urgent = false;
if (test_opt(sbi, LFS))
return false;
+
+ down_read(&sbi->gc_rwsem);
if (sbi->gc_thread && sbi->gc_thread->gc_urgent)
- return true;
+ gc_urgent = true;
+ up_read(&sbi->gc_rwsem);
+
+ if (gc_urgent)
+ return false;
return free_sections(sbi) <= (node_secs + 2 * dent_secs + imeta_secs +
SM_I(sbi)->min_ssr_sections + reserved_sections(sbi));
@@ -1421,8 +1428,10 @@ static int issue_discard_thread(void *data)
if (dcc->discard_wake)
dcc->discard_wake = 0;
+ down_read(&sbi->gc_rwsem);
if (sbi->gc_thread && sbi->gc_thread->gc_urgent)
init_discard_policy(&dpolicy, DPOLICY_FORCE, 1);
+ up_read(&sbi->gc_rwsem);
sb_start_intwrite(sbi->sb);
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index c8e5fe5d71fe..294be9e92aee 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -1476,15 +1476,23 @@ static int f2fs_remount(struct super_block *sb, int
*flags, char *data)
* option. Also sync the filesystem.
*/
if ((*flags & SB_RDONLY) || !test_opt(sbi, BG_GC)) {
+ down_write(&sbi->gc_rwsem);
if (sbi->gc_thread) {
stop_gc_thread(sbi);
need_restart_gc = true;
}
- } else if (!sbi->gc_thread) {
- err = start_gc_thread(sbi);
- if (err)
- goto restore_opts;
- need_stop_gc = true;
+ up_write(&sbi->gc_rwsem);
+ } else {
+ down_write(&sbi->gc_rwsem);
+ if (!sbi->gc_thread) {
+ err = start_gc_thread(sbi);
+ if (e
