There are redundant lines in allocate_data_block.
In this function, we call refresh_sit_entry with old seg and old curseg.
After that, we call locate_dirty_segment with old curseg.
But, the new address is always allocated from old curseg and
we call locate_dirty_segment with old curseg in refresh_sit_entry.
So, we do not need to call locate_dirty_segment with old curseg again.
We've discussed like below:
Jaegeuk said:
"When considering SSR, we need to take care of the following scenario.
- old segno : X
- new address : Z
- old curseg : Y
This means, a new block is supposed to be written to Z from X.
And Z is newly allocated in the same path from Y.
In that case, we should trigger locate_dirty_segment for Y, since
it was a current_segment and can be dirty owing to SSR.
But that was not included in the dirty list."
Changman said:
"We already choosed old curseg(Y) and then we allocate new address(Z) from old
curseg(Y). After that we call refresh_sit_entry(old address, new address).
In the funcation, we call locate_dirty_segment with old seg and old curseg.
So calling locate_dirty_segment after refresh_sit_entry again is redundant."
Jaegeuk said:
"Right. The new address is always allocated from old_curseg."
Signed-off-by: Dongho Sim <[email protected]>
---
fs/f2fs/segment.c | 3 ---
1 file changed, 3 deletions(-)
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 8a6e57d..7af4a8d 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -973,14 +973,12 @@ void allocate_data_block(struct f2fs_sb_info *sbi, struct page *page,
{
struct sit_info *sit_i = SIT_I(sbi);
struct curseg_info *curseg;
- unsigned int old_cursegno;
curseg = CURSEG_I(sbi, type);
mutex_lock(&curseg->curseg_mutex);
*new_blkaddr = NEXT_FREE_BLKADDR(sbi, curseg);
- old_cursegno = curseg->segno;
/*
* __add_sum_entry should be resided under the curseg_mutex
@@ -1001,7 +999,6 @@ void allocate_data_block(struct f2fs_sb_info *sbi, struct page *page,
* since SSR needs latest valid block information.
*/
refresh_sit_entry(sbi, old_blkaddr, *new_blkaddr);
- locate_dirty_segment(sbi, old_cursegno);
mutex_unlock(&sit_i->sentry_lock);
--
1.9.1
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> -----Original Message-----
> From: Dongho Sim [mailto:[email protected]]
> Sent: Wednesday, July 30, 2014 2:53 PM
> To: [email protected]
> Cc: [email protected]; [email protected];
> [email protected]
> Subject: [f2fs-dev] [PATCH v2] f2fs: remove redundant lines in allocate_data_block
>
> There are redundant lines in allocate_data_block.
>
> In this function, we call refresh_sit_entry with old seg and old curseg.
> After that, we call locate_dirty_segment with old curseg.
>
> But, the new address is always allocated from old curseg and
> we call locate_dirty_segment with old curseg in refresh_sit_entry.
> So, we do not need to call locate_dirty_segment with old curseg again.
>
> We've discussed like below:
>
> Jaegeuk said:
> "When considering SSR, we need to take care of the following scenario.
> - old segno : X
> - new address : Z
> - old curseg : Y
> This means, a new block is supposed to be written to Z from X.
> And Z is newly allocated in the same path from Y.
>
> In that case, we should trigger locate_dirty_segment for Y, since
> it was a current_segment and can be dirty owing to SSR.
> But that was not included in the dirty list."
>
> Changman said:
> "We already choosed old curseg(Y) and then we allocate new address(Z) from old
> curseg(Y). After that we call refresh_sit_entry(old address, new address).
> In the funcation, we call locate_dirty_segment with old seg and old curseg.
> So calling locate_dirty_segment after refresh_sit_entry again is redundant."
>
> Jaegeuk said:
> "Right. The new address is always allocated from old_curseg."
>
> Signed-off-by: Dongho Sim <[email protected]>
Reviewed-by: Chao Yu <[email protected]>
> ---
> fs/f2fs/segment.c | 3 ---
> 1 file changed, 3 deletions(-)
>
> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> index 8a6e57d..7af4a8d 100644
> --- a/fs/f2fs/segment.c
> +++ b/fs/f2fs/segment.c
> @@ -973,14 +973,12 @@ void allocate_data_block(struct f2fs_sb_info *sbi, struct page *page,
> {
> struct sit_info *sit_i = SIT_I(sbi);
> struct curseg_info *curseg;
> - unsigned int old_cursegno;
>
> curseg = CURSEG_I(sbi, type);
>
> mutex_lock(&curseg->curseg_mutex);
>
> *new_blkaddr = NEXT_FREE_BLKADDR(sbi, curseg);
> - old_cursegno = curseg->segno;
>
> /*
> * __add_sum_entry should be resided under the curseg_mutex
> @@ -1001,7 +999,6 @@ void allocate_data_block(struct f2fs_sb_info *sbi, struct page *page,
> * since SSR needs latest valid block information.
> */
> refresh_sit_entry(sbi, old_blkaddr, *new_blkaddr);
> - locate_dirty_segment(sbi, old_cursegno);
>
> mutex_unlock(&sit_i->sentry_lock);
>
> --
> 1.9.1
>
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