2022-08-19 23:26:43

by Jaegeuk Kim

[permalink] [raw]
Subject: [PATCH 1/2] f2fs: flush pending checkpoints when freezing super

This avoids -EINVAL when trying to freeze f2fs.

Signed-off-by: Jaegeuk Kim <[email protected]>
---
fs/f2fs/checkpoint.c | 27 +++++++++++++++++++++------
fs/f2fs/f2fs.h | 1 +
fs/f2fs/super.c | 5 ++---
3 files changed, 24 insertions(+), 9 deletions(-)

diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
index 8259e0fa97e1..37f7a9ea4746 100644
--- a/fs/f2fs/checkpoint.c
+++ b/fs/f2fs/checkpoint.c
@@ -1892,15 +1892,30 @@ int f2fs_start_ckpt_thread(struct f2fs_sb_info *sbi)
void f2fs_stop_ckpt_thread(struct f2fs_sb_info *sbi)
{
struct ckpt_req_control *cprc = &sbi->cprc_info;
+ struct task_struct *ckpt_task;

- if (cprc->f2fs_issue_ckpt) {
- struct task_struct *ckpt_task = cprc->f2fs_issue_ckpt;
+ if (!cprc->f2fs_issue_ckpt)
+ return;

- cprc->f2fs_issue_ckpt = NULL;
- kthread_stop(ckpt_task);
+ ckpt_task = cprc->f2fs_issue_ckpt;
+ cprc->f2fs_issue_ckpt = NULL;
+ kthread_stop(ckpt_task);

- flush_remained_ckpt_reqs(sbi, NULL);
- }
+ f2fs_flush_ckpt_thread(sbi);
+}
+
+void f2fs_flush_ckpt_thread(struct f2fs_sb_info *sbi)
+{
+ struct ckpt_req_control *cprc = &sbi->cprc_info;
+
+ if (!cprc->f2fs_issue_ckpt)
+ return;
+
+ flush_remained_ckpt_reqs(sbi, NULL);
+
+ /* Let's wait for the previous dispatched checkpoint. */
+ while (atomic_read(&cprc->queued_ckpt))
+ io_schedule_timeout(DEFAULT_IO_TIMEOUT);
}

void f2fs_init_ckpt_req_control(struct f2fs_sb_info *sbi)
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 3c7cdb70fe2e..2a83fc34b372 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -3707,6 +3707,7 @@ static inline bool f2fs_need_rand_seg(struct f2fs_sb_info *sbi)
* checkpoint.c
*/
void f2fs_stop_checkpoint(struct f2fs_sb_info *sbi, bool end_io);
+void f2fs_flush_ckpt_thread(struct f2fs_sb_info *sbi);
struct page *f2fs_grab_meta_page(struct f2fs_sb_info *sbi, pgoff_t index);
struct page *f2fs_get_meta_page(struct f2fs_sb_info *sbi, pgoff_t index);
struct page *f2fs_get_meta_page_retry(struct f2fs_sb_info *sbi, pgoff_t index);
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index 212ec2b4926b..48ac3de4a533 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -1670,9 +1670,8 @@ static int f2fs_freeze(struct super_block *sb)
if (is_sbi_flag_set(F2FS_SB(sb), SBI_IS_DIRTY))
return -EINVAL;

- /* ensure no checkpoint required */
- if (!llist_empty(&F2FS_SB(sb)->cprc_info.issue_list))
- return -EINVAL;
+ /* Let's flush checkpoints and stop the thread. */
+ f2fs_flush_ckpt_thread(F2FS_SB(sb));

/* to avoid deadlock on f2fs_evict_inode->SB_FREEZE_FS */
set_sbi_flag(F2FS_SB(sb), SBI_IS_FREEZING);
--
2.37.1.595.g718a3a8f04-goog


2022-08-19 23:26:47

by Jaegeuk Kim

[permalink] [raw]
Subject: [PATCH 2/2] f2fs: complete checkpoints during remount

Otherwise, pending checkpoints can contribute a race condition to give a
quota warning.

- Thread - checkpoint thread
add checkpoints to the list
do_remount()
down_write(&sb->s_umount);
f2fs_remount()
block_operations()
down_read_trylock(&sb->s_umount) = 0
up_write(&sb->s_umount);
f2fs_quota_sync()
dquot_writeback_dquots()
WARN_ON_ONCE(!rwsem_is_locked(&sb->s_umount));

Signed-off-by: Jaegeuk Kim <[email protected]>
---
fs/f2fs/super.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index 48ac3de4a533..88879c483805 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -2349,6 +2349,9 @@ static int f2fs_remount(struct super_block *sb, int *flags, char *data)
f2fs_stop_ckpt_thread(sbi);
need_restart_ckpt = true;
} else {
+ /* flush if the prevous checkpoint, if exists. */
+ f2fs_flush_ckpt_thread(sbi);
+
err = f2fs_start_ckpt_thread(sbi);
if (err) {
f2fs_err(sbi,
--
2.37.1.595.g718a3a8f04-goog

2022-08-24 20:53:16

by Jaegeuk Kim

[permalink] [raw]
Subject: Re: [PATCH 1/2] f2fs: flush pending checkpoints when freezing super

This avoids -EINVAL when trying to freeze f2fs.

Signed-off-by: Jaegeuk Kim <[email protected]>
---

Change log from v1:
- do not check cprc->f2fs_issue_ckpt in f2fs_flush_ckpt_thread

fs/f2fs/checkpoint.c | 24 ++++++++++++++++++------
fs/f2fs/f2fs.h | 1 +
fs/f2fs/super.c | 5 ++---
3 files changed, 21 insertions(+), 9 deletions(-)

diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
index 7de48e791920..7bf1feb5ac78 100644
--- a/fs/f2fs/checkpoint.c
+++ b/fs/f2fs/checkpoint.c
@@ -1893,15 +1893,27 @@ int f2fs_start_ckpt_thread(struct f2fs_sb_info *sbi)
void f2fs_stop_ckpt_thread(struct f2fs_sb_info *sbi)
{
struct ckpt_req_control *cprc = &sbi->cprc_info;
+ struct task_struct *ckpt_task;

- if (cprc->f2fs_issue_ckpt) {
- struct task_struct *ckpt_task = cprc->f2fs_issue_ckpt;
+ if (!cprc->f2fs_issue_ckpt)
+ return;

- cprc->f2fs_issue_ckpt = NULL;
- kthread_stop(ckpt_task);
+ ckpt_task = cprc->f2fs_issue_ckpt;
+ cprc->f2fs_issue_ckpt = NULL;
+ kthread_stop(ckpt_task);

- flush_remained_ckpt_reqs(sbi, NULL);
- }
+ f2fs_flush_ckpt_thread(sbi);
+}
+
+void f2fs_flush_ckpt_thread(struct f2fs_sb_info *sbi)
+{
+ struct ckpt_req_control *cprc = &sbi->cprc_info;
+
+ flush_remained_ckpt_reqs(sbi, NULL);
+
+ /* Let's wait for the previous dispatched checkpoint. */
+ while (atomic_read(&cprc->queued_ckpt))
+ io_schedule_timeout(DEFAULT_IO_TIMEOUT);
}

void f2fs_init_ckpt_req_control(struct f2fs_sb_info *sbi)
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 6770210aae70..088c3d1574b8 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -3711,6 +3711,7 @@ static inline bool f2fs_need_rand_seg(struct f2fs_sb_info *sbi)
* checkpoint.c
*/
void f2fs_stop_checkpoint(struct f2fs_sb_info *sbi, bool end_io);
+void f2fs_flush_ckpt_thread(struct f2fs_sb_info *sbi);
struct page *f2fs_grab_meta_page(struct f2fs_sb_info *sbi, pgoff_t index);
struct page *f2fs_get_meta_page(struct f2fs_sb_info *sbi, pgoff_t index);
struct page *f2fs_get_meta_page_retry(struct f2fs_sb_info *sbi, pgoff_t index);
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index e910f0e39d76..4f2ff50b247c 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -1671,9 +1671,8 @@ static int f2fs_freeze(struct super_block *sb)
if (is_sbi_flag_set(F2FS_SB(sb), SBI_IS_DIRTY))
return -EINVAL;

- /* ensure no checkpoint required */
- if (!llist_empty(&F2FS_SB(sb)->cprc_info.issue_list))
- return -EINVAL;
+ /* Let's flush checkpoints and stop the thread. */
+ f2fs_flush_ckpt_thread(F2FS_SB(sb));

/* to avoid deadlock on f2fs_evict_inode->SB_FREEZE_FS */
set_sbi_flag(F2FS_SB(sb), SBI_IS_FREEZING);
--
2.37.1.595.g718a3a8f04-goog

2022-08-24 21:11:18

by Jaegeuk Kim

[permalink] [raw]
Subject: Re: [PATCH 2/2 v2] f2fs: complete checkpoints during remount

Otherwise, pending checkpoints can contribute a race condition to give a
quota warning.

- Thread - checkpoint thread
add checkpoints to the list
do_remount()
down_write(&sb->s_umount);
f2fs_remount()
block_operations()
down_read_trylock(&sb->s_umount) = 0
up_write(&sb->s_umount);
f2fs_quota_sync()
dquot_writeback_dquots()
WARN_ON_ONCE(!rwsem_is_locked(&sb->s_umount));

Or,

do_remount()
down_write(&sb->s_umount);
f2fs_remount()
create a ckpt thread
f2fs_enable_checkpoint() adds checkpoints
wait for f2fs_sync_fs()
trigger another pending checkpoint
block_operations()
down_read_trylock(&sb->s_umount) = 0
up_write(&sb->s_umount);
f2fs_quota_sync()
dquot_writeback_dquots()
WARN_ON_ONCE(!rwsem_is_locked(&sb->s_umount));

Signed-off-by: Jaegeuk Kim <[email protected]>
---

Change log from v1:
- add one more case

fs/f2fs/super.c | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index 4f2ff50b247c..0f29c759a898 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -2185,6 +2185,9 @@ static void f2fs_enable_checkpoint(struct f2fs_sb_info *sbi)
f2fs_up_write(&sbi->gc_lock);

f2fs_sync_fs(sbi->sb, 1);
+
+ /* Let's ensure there's no pending checkpoint anymore */
+ f2fs_flush_ckpt_thread(sbi);
}

static int f2fs_remount(struct super_block *sb, int *flags, char *data)
@@ -2350,6 +2353,9 @@ static int f2fs_remount(struct super_block *sb, int *flags, char *data)
f2fs_stop_ckpt_thread(sbi);
need_restart_ckpt = true;
} else {
+ /* Flush if the prevous checkpoint, if exists. */
+ f2fs_flush_ckpt_thread(sbi);
+
err = f2fs_start_ckpt_thread(sbi);
if (err) {
f2fs_err(sbi,
--
2.37.1.595.g718a3a8f04-goog

2022-09-13 03:17:46

by Chao Yu

[permalink] [raw]
Subject: Re: [f2fs-dev] [PATCH 1/2] f2fs: flush pending checkpoints when freezing super

On 2022/8/25 4:02, Jaegeuk Kim wrote:
> This avoids -EINVAL when trying to freeze f2fs.
>
> Signed-off-by: Jaegeuk Kim <[email protected]>

Reviewed-by: Chao Yu <[email protected]>

Thanks,

2022-09-13 03:32:28

by Chao Yu

[permalink] [raw]
Subject: Re: [f2fs-dev] [PATCH 2/2 v2] f2fs: complete checkpoints during remount

On 2022/8/25 4:30, Jaegeuk Kim wrote:
> Otherwise, pending checkpoints can contribute a race condition to give a
> quota warning.
>
> - Thread - checkpoint thread
> add checkpoints to the list
> do_remount()
> down_write(&sb->s_umount);
> f2fs_remount()
> block_operations()
> down_read_trylock(&sb->s_umount) = 0
> up_write(&sb->s_umount);
> f2fs_quota_sync()
> dquot_writeback_dquots()
> WARN_ON_ONCE(!rwsem_is_locked(&sb->s_umount));
>
> Or,
>
> do_remount()
> down_write(&sb->s_umount);
> f2fs_remount()
> create a ckpt thread
> f2fs_enable_checkpoint() adds checkpoints
> wait for f2fs_sync_fs()
> trigger another pending checkpoint
> block_operations()
> down_read_trylock(&sb->s_umount) = 0
> up_write(&sb->s_umount);
> f2fs_quota_sync()
> dquot_writeback_dquots()
> WARN_ON_ONCE(!rwsem_is_locked(&sb->s_umount));
>
> Signed-off-by: Jaegeuk Kim <[email protected]>

Reviewed-by: Chao Yu <[email protected]>

Thanks,