[PATCH v2] f2fs: fix wrong inflight page stats for directIO

[PATCH v2] f2fs: fix wrong inflight page stats for directIO

[Chao Yu]

Previously, we use sbi->nr_pages[] to account direct IO, the count should
be based on page granularity rather than bio granularity, fix it.

Fixes: 02b16d0a34a1 ("f2fs: add to account direct IO")
Signed-off-by: Chao Yu <chao@kernel.org>
---
v2:
- There is one missing line when I reorder in development patches,
so just resend the patch as v2, sorry.
 fs/f2fs/data.c | 11 +++++++----
 fs/f2fs/f2fs.h | 13 +++++++++++++
 2 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index e6f107de4c92..095350ccf80d 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -3494,8 +3494,9 @@ static void f2fs_dio_end_io(struct bio *bio)
 {
 	struct f2fs_private_dio *dio = bio->bi_private;
 
-	dec_page_count(F2FS_I_SB(dio->inode),
-			dio->write ? F2FS_DIO_WRITE : F2FS_DIO_READ);
+	dec_page_counts(F2FS_I_SB(dio->inode),
+			dio->write ? F2FS_DIO_WRITE : F2FS_DIO_READ,
+			dio->blkcnt);
 
 	bio->bi_private = dio->orig_private;
 	bio->bi_end_io = dio->orig_end_io;
@@ -3510,6 +3511,7 @@ static void f2fs_dio_submit_bio(struct bio *bio, struct inode *inode,
 {
 	struct f2fs_private_dio *dio;
 	bool write = (bio_op(bio) == REQ_OP_WRITE);
+	unsigned int blkcnt = bio_sectors(bio) >> F2FS_LOG_SECTORS_PER_BLOCK;
 
 	dio = f2fs_kzalloc(F2FS_I_SB(inode),
 			sizeof(struct f2fs_private_dio), GFP_NOFS);
@@ -3519,13 +3521,14 @@ static void f2fs_dio_submit_bio(struct bio *bio, struct inode *inode,
 	dio->inode = inode;
 	dio->orig_end_io = bio->bi_end_io;
 	dio->orig_private = bio->bi_private;
+	dio->blkcnt = blkcnt;
 	dio->write = write;
 
 	bio->bi_end_io = f2fs_dio_end_io;
 	bio->bi_private = dio;
 
-	inc_page_count(F2FS_I_SB(inode),
-			write ? F2FS_DIO_WRITE : F2FS_DIO_READ);
+	inc_page_counts(F2FS_I_SB(inode),
+			write ? F2FS_DIO_WRITE : F2FS_DIO_READ, dio->blkcnt);
 
 	submit_bio(bio);
 	return;
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 867f2c5d9559..7369f8087f64 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -1759,6 +1759,7 @@ struct f2fs_private_dio {
 	struct inode *inode;
 	void *orig_private;
 	bio_end_io_t *orig_end_io;
+	unsigned int blkcnt;
 	bool write;
 };
 
@@ -2267,6 +2268,12 @@ static inline void inc_page_count(struct f2fs_sb_info *sbi, int count_type)
 		set_sbi_flag(sbi, SBI_IS_DIRTY);
 }
 
+static inline void inc_page_counts(struct f2fs_sb_info *sbi, int count_type,
+							unsigned int count)
+{
+	atomic_add(count, &sbi->nr_pages[count_type]);
+}
+
 static inline void inode_inc_dirty_pages(struct inode *inode)
 {
 	atomic_inc(&F2FS_I(inode)->dirty_pages);
@@ -2281,6 +2288,12 @@ static inline void dec_page_count(struct f2fs_sb_info *sbi, int count_type)
 	atomic_dec(&sbi->nr_pages[count_type]);
 }
 
+static inline void dec_page_counts(struct f2fs_sb_info *sbi, int count_type,
+							unsigned int count)
+{
+	atomic_sub(count, &sbi->nr_pages[count_type]);
+}
+
 static inline void inode_dec_dirty_pages(struct inode *inode)
 {
 	if (!S_ISDIR(inode->i_mode) && !S_ISREG(inode->i_mode) &&
-- 
2.22.1

Re: [f2fs-dev] [PATCH v2] f2fs: fix wrong inflight page stats for directIO

[Eric Biggers]

On Mon, Jul 19, 2021 at 04:45:48PM +0800, Chao Yu wrote:
> Previously, we use sbi->nr_pages[] to account direct IO, the count should
> be based on page granularity rather than bio granularity, fix it.
> 
> Fixes: 02b16d0a34a1 ("f2fs: add to account direct IO")
> Signed-off-by: Chao Yu <chao@kernel.org>
> ---
> v2:
> - There is one missing line when I reorder in development patches,
> so just resend the patch as v2, sorry.
>  fs/f2fs/data.c | 11 +++++++----
>  fs/f2fs/f2fs.h | 13 +++++++++++++
>  2 files changed, 20 insertions(+), 4 deletions(-)
> 
> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> index e6f107de4c92..095350ccf80d 100644
> --- a/fs/f2fs/data.c
> +++ b/fs/f2fs/data.c
> @@ -3494,8 +3494,9 @@ static void f2fs_dio_end_io(struct bio *bio)
>  {
>  	struct f2fs_private_dio *dio = bio->bi_private;
>  
> -	dec_page_count(F2FS_I_SB(dio->inode),
> -			dio->write ? F2FS_DIO_WRITE : F2FS_DIO_READ);
> +	dec_page_counts(F2FS_I_SB(dio->inode),
> +			dio->write ? F2FS_DIO_WRITE : F2FS_DIO_READ,
> +			dio->blkcnt);
>  
>  	bio->bi_private = dio->orig_private;
>  	bio->bi_end_io = dio->orig_end_io;
> @@ -3510,6 +3511,7 @@ static void f2fs_dio_submit_bio(struct bio *bio, struct inode *inode,
>  {
>  	struct f2fs_private_dio *dio;
>  	bool write = (bio_op(bio) == REQ_OP_WRITE);
> +	unsigned int blkcnt = bio_sectors(bio) >> F2FS_LOG_SECTORS_PER_BLOCK;
>  
>  	dio = f2fs_kzalloc(F2FS_I_SB(inode),
>  			sizeof(struct f2fs_private_dio), GFP_NOFS);
> @@ -3519,13 +3521,14 @@ static void f2fs_dio_submit_bio(struct bio *bio, struct inode *inode,
>  	dio->inode = inode;
>  	dio->orig_end_io = bio->bi_end_io;
>  	dio->orig_private = bio->bi_private;
> +	dio->blkcnt = blkcnt;
>  	dio->write = write;
>  
>  	bio->bi_end_io = f2fs_dio_end_io;
>  	bio->bi_private = dio;
>  
> -	inc_page_count(F2FS_I_SB(inode),
> -			write ? F2FS_DIO_WRITE : F2FS_DIO_READ);
> +	inc_page_counts(F2FS_I_SB(inode),
> +			write ? F2FS_DIO_WRITE : F2FS_DIO_READ, dio->blkcnt);
>  
>  	submit_bio(bio);
>  	return;
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index 867f2c5d9559..7369f8087f64 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -1759,6 +1759,7 @@ struct f2fs_private_dio {
>  	struct inode *inode;
>  	void *orig_private;
>  	bio_end_io_t *orig_end_io;
> +	unsigned int blkcnt;
>  	bool write;
>  };
>  
> @@ -2267,6 +2268,12 @@ static inline void inc_page_count(struct f2fs_sb_info *sbi, int count_type)
>  		set_sbi_flag(sbi, SBI_IS_DIRTY);
>  }
>  
> +static inline void inc_page_counts(struct f2fs_sb_info *sbi, int count_type,
> +							unsigned int count)
> +{
> +	atomic_add(count, &sbi->nr_pages[count_type]);
> +}
> +
>  static inline void inode_inc_dirty_pages(struct inode *inode)
>  {
>  	atomic_inc(&F2FS_I(inode)->dirty_pages);
> @@ -2281,6 +2288,12 @@ static inline void dec_page_count(struct f2fs_sb_info *sbi, int count_type)
>  	atomic_dec(&sbi->nr_pages[count_type]);
>  }
>  
> +static inline void dec_page_counts(struct f2fs_sb_info *sbi, int count_type,
> +							unsigned int count)
> +{
> +	atomic_sub(count, &sbi->nr_pages[count_type]);
> +}
> +

Please give these proper names like add_to_page_count() and
sub_from_page_count().  They change one counter, not multiple.

- Eric

Re: [f2fs-dev] [PATCH v2] f2fs: fix wrong inflight page stats for directIO

[Eric Biggers]

On Wed, Jul 21, 2021 at 05:46:26PM -0700, Eric Biggers wrote:
> On Mon, Jul 19, 2021 at 04:45:48PM +0800, Chao Yu wrote:
> > Previously, we use sbi->nr_pages[] to account direct IO, the count should
> > be based on page granularity rather than bio granularity, fix it.
> > 
> > Fixes: 02b16d0a34a1 ("f2fs: add to account direct IO")
> > Signed-off-by: Chao Yu <chao@kernel.org>

Also, do we have to do this, as opposed to just moving F2FS_DIO_WRITE and
F2FS_DIO_READ out of ->nr_pages[] and into separate counters that are clearly
defined to be per-request?  As Christoph pointed out
(https://lkml.kernel.org/r/YPU+3inGclUtcSpJ@infradead.org), these counters are
only used to check whether there is any in-flight direct I/O at all.  (They're
also shown in /sys/kernel/debug/f2fs/status, but that doesn't really matter.)

As Christoph mentioned, there is a way to avoid needing f2fs_dio_submit_bio()
(which would save a memory allocation for every bio, which can fail).  But it
will only work if the counters remain per-request.

Can we leave these as per-request?

- Eric

Re: [f2fs-dev] [PATCH v2] f2fs: fix wrong inflight page stats for directIO

[Chao Yu]

On 2021/7/22 9:42, Eric Biggers wrote:
> On Wed, Jul 21, 2021 at 05:46:26PM -0700, Eric Biggers wrote:
>> On Mon, Jul 19, 2021 at 04:45:48PM +0800, Chao Yu wrote:
>>> Previously, we use sbi->nr_pages[] to account direct IO, the count should
>>> be based on page granularity rather than bio granularity, fix it.
>>>
>>> Fixes: 02b16d0a34a1 ("f2fs: add to account direct IO")
>>> Signed-off-by: Chao Yu <chao@kernel.org>
> 
> Also, do we have to do this, as opposed to just moving F2FS_DIO_WRITE and
> F2FS_DIO_READ out of ->nr_pages[] and into separate counters that are clearly
> defined to be per-request?  As Christoph pointed out
> (https://lkml.kernel.org/r/YPU+3inGclUtcSpJ@infradead.org), these counters are
> only used to check whether there is any in-flight direct I/O at all.  (They're
> also shown in /sys/kernel/debug/f2fs/status, but that doesn't really matter.)
> 
> As Christoph mentioned, there is a way to avoid needing f2fs_dio_submit_bio()
> (which would save a memory allocation for every bio, which can fail).  But it
> will only work if the counters remain per-request.
> 
> Can we leave these as per-request?

I updated the patch, could you please check that?

Thanks,

> 
> - Eric
>