diff mbox series

[RFC,v2,05/25] ext4: make ext4_map_blocks() distinguish delalloc only extent

Message ID 20240102123918.799062-6-yi.zhang@huaweicloud.com (mailing list archive)
State New
Headers show
Series ext4: use iomap for regular file's buffered IO path and enable large foilo | expand

Commit Message

Zhang Yi Jan. 2, 2024, 12:38 p.m. UTC 
From: Zhang Yi <yi.zhang@huawei.com>

Add a new map flag EXT4_MAP_DELAYED to indicate the mapping range is a
delayed allocated only (not unwritten) one, and making
ext4_map_blocks() can distinguish it, no longer mixing it with holes.

Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
---
 fs/ext4/ext4.h    | 4 +++-
 fs/ext4/extents.c | 5 +++--
 fs/ext4/inode.c   | 2 ++
 3 files changed, 8 insertions(+), 3 deletions(-)

Comments

Jan Kara Jan. 3, 2024, 11:31 a.m. UTC | #1 
On Tue 02-01-24 20:38:58, Zhang Yi wrote:
> From: Zhang Yi <yi.zhang@huawei.com>
> 
> Add a new map flag EXT4_MAP_DELAYED to indicate the mapping range is a
> delayed allocated only (not unwritten) one, and making
> ext4_map_blocks() can distinguish it, no longer mixing it with holes.
> 
> Signed-off-by: Zhang Yi <yi.zhang@huawei.com>

One small comment below.

> ---
>  fs/ext4/ext4.h    | 4 +++-
>  fs/ext4/extents.c | 5 +++--
>  fs/ext4/inode.c   | 2 ++
>  3 files changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
> index a5d784872303..55195909d32f 100644
> --- a/fs/ext4/ext4.h
> +++ b/fs/ext4/ext4.h
> @@ -252,8 +252,10 @@ struct ext4_allocation_request {
>  #define EXT4_MAP_MAPPED		BIT(BH_Mapped)
>  #define EXT4_MAP_UNWRITTEN	BIT(BH_Unwritten)
>  #define EXT4_MAP_BOUNDARY	BIT(BH_Boundary)
> +#define EXT4_MAP_DELAYED	BIT(BH_Delay)
>  #define EXT4_MAP_FLAGS		(EXT4_MAP_NEW | EXT4_MAP_MAPPED |\
> -				 EXT4_MAP_UNWRITTEN | EXT4_MAP_BOUNDARY)
> +				 EXT4_MAP_UNWRITTEN | EXT4_MAP_BOUNDARY |\
> +				 EXT4_MAP_DELAYED)
>  
>  struct ext4_map_blocks {
>  	ext4_fsblk_t m_pblk;
> diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
> index 0892d0568013..fc69f13cf510 100644
> --- a/fs/ext4/extents.c
> +++ b/fs/ext4/extents.c
> @@ -4073,9 +4073,10 @@ static void ext4_ext_determine_hole(struct inode *inode,
>  	} else if (in_range(map->m_lblk, es.es_lblk, es.es_len)) {
>  		/*
>  		 * Straddle the beginning of the queried range, it's no
> -		 * longer a hole, adjust the length to the delayed extent's
> -		 * after map->m_lblk.
> +		 * longer a hole, mark it is a delalloc and adjust the
> +		 * length to the delayed extent's after map->m_lblk.
>  		 */
> +		map->m_flags |= EXT4_MAP_DELAYED;

I wouldn't set delalloc bit here. If there's delalloc extent containing
lblk now, it means the caller of ext4_map_blocks() is not holding i_rwsem
(otherwise we would have found already in ext4_map_blocks()) and thus
delalloc info is unreliable anyway. So I wouldn't bother. But it's worth a
comment here like:

		/*
		 * There's delalloc extent containing lblk. It must have
		 * been added after ext4_map_blocks() checked the extent
		 * status tree so we are not holding i_rwsem and delalloc
		 * info is only stabilized by i_data_sem we are going to
		 * release soon. Don't modify the extent status tree and
		 * report extent as a hole.
		 */

								Honza

>  		len = es.es_lblk + es.es_len - map->m_lblk;
>  		goto out;
>  	} else {
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 1b5e6409f958..c141bf6d8db2 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -515,6 +515,8 @@ int ext4_map_blocks(handle_t *handle, struct inode *inode,
>  			map->m_len = retval;
>  		} else if (ext4_es_is_delayed(&es) || ext4_es_is_hole(&es)) {
>  			map->m_pblk = 0;
> +			map->m_flags |= ext4_es_is_delayed(&es) ?
> +					EXT4_MAP_DELAYED : 0;
>  			retval = es.es_len - (map->m_lblk - es.es_lblk);
>  			if (retval > map->m_len)
>  				retval = map->m_len;
> -- 
> 2.39.2
>
Zhang Yi Jan. 3, 2024, 1:20 p.m. UTC | #2 
On 2024/1/3 19:31, Jan Kara wrote:
> On Tue 02-01-24 20:38:58, Zhang Yi wrote:
>> From: Zhang Yi <yi.zhang@huawei.com>
>>
>> Add a new map flag EXT4_MAP_DELAYED to indicate the mapping range is a
>> delayed allocated only (not unwritten) one, and making
>> ext4_map_blocks() can distinguish it, no longer mixing it with holes.
>>
>> Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
> 
> One small comment below.
> 
>> ---
>>  fs/ext4/ext4.h    | 4 +++-
>>  fs/ext4/extents.c | 5 +++--
>>  fs/ext4/inode.c   | 2 ++
>>  3 files changed, 8 insertions(+), 3 deletions(-)
>>
>> diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
>> index a5d784872303..55195909d32f 100644
>> --- a/fs/ext4/ext4.h
>> +++ b/fs/ext4/ext4.h
>> @@ -252,8 +252,10 @@ struct ext4_allocation_request {
>>  #define EXT4_MAP_MAPPED		BIT(BH_Mapped)
>>  #define EXT4_MAP_UNWRITTEN	BIT(BH_Unwritten)
>>  #define EXT4_MAP_BOUNDARY	BIT(BH_Boundary)
>> +#define EXT4_MAP_DELAYED	BIT(BH_Delay)
>>  #define EXT4_MAP_FLAGS		(EXT4_MAP_NEW | EXT4_MAP_MAPPED |\
>> -				 EXT4_MAP_UNWRITTEN | EXT4_MAP_BOUNDARY)
>> +				 EXT4_MAP_UNWRITTEN | EXT4_MAP_BOUNDARY |\
>> +				 EXT4_MAP_DELAYED)
>>  
>>  struct ext4_map_blocks {
>>  	ext4_fsblk_t m_pblk;
>> diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
>> index 0892d0568013..fc69f13cf510 100644
>> --- a/fs/ext4/extents.c
>> +++ b/fs/ext4/extents.c
>> @@ -4073,9 +4073,10 @@ static void ext4_ext_determine_hole(struct inode *inode,
>>  	} else if (in_range(map->m_lblk, es.es_lblk, es.es_len)) {
>>  		/*
>>  		 * Straddle the beginning of the queried range, it's no
>> -		 * longer a hole, adjust the length to the delayed extent's
>> -		 * after map->m_lblk.
>> +		 * longer a hole, mark it is a delalloc and adjust the
>> +		 * length to the delayed extent's after map->m_lblk.
>>  		 */
>> +		map->m_flags |= EXT4_MAP_DELAYED;
> 
> I wouldn't set delalloc bit here. If there's delalloc extent containing
> lblk now, it means the caller of ext4_map_blocks() is not holding i_rwsem
> (otherwise we would have found already in ext4_map_blocks()) and thus
> delalloc info is unreliable anyway. So I wouldn't bother. But it's worth a
> comment here like:
> 
> 		/*
> 		 * There's delalloc extent containing lblk. It must have
> 		 * been added after ext4_map_blocks() checked the extent
> 		 * status tree so we are not holding i_rwsem and delalloc
> 		 * info is only stabilized by i_data_sem we are going to
> 		 * release soon. Don't modify the extent status tree and
> 		 * report extent as a hole.
> 		 */
> 

Yeah, the delalloc info is still unreliable. Thanks for the advice, I
will revise it in my next iteration along with your advice in patch 03.

Thanks,
Yi.

> 
>>  		len = es.es_lblk + es.es_len - map->m_lblk;
>>  		goto out;
>>  	} else {
>> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
>> index 1b5e6409f958..c141bf6d8db2 100644
>> --- a/fs/ext4/inode.c
>> +++ b/fs/ext4/inode.c
>> @@ -515,6 +515,8 @@ int ext4_map_blocks(handle_t *handle, struct inode *inode,
>>  			map->m_len = retval;
>>  		} else if (ext4_es_is_delayed(&es) || ext4_es_is_hole(&es)) {
>>  			map->m_pblk = 0;
>> +			map->m_flags |= ext4_es_is_delayed(&es) ?
>> +					EXT4_MAP_DELAYED : 0;
>>  			retval = es.es_len - (map->m_lblk - es.es_lblk);
>>  			if (retval > map->m_len)
>>  				retval = map->m_len;
>> -- 
>> 2.39.2
>>
diff mbox series

Patch

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index a5d784872303..55195909d32f 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -252,8 +252,10 @@  struct ext4_allocation_request {
 #define EXT4_MAP_MAPPED		BIT(BH_Mapped)
 #define EXT4_MAP_UNWRITTEN	BIT(BH_Unwritten)
 #define EXT4_MAP_BOUNDARY	BIT(BH_Boundary)
+#define EXT4_MAP_DELAYED	BIT(BH_Delay)
 #define EXT4_MAP_FLAGS		(EXT4_MAP_NEW | EXT4_MAP_MAPPED |\
-				 EXT4_MAP_UNWRITTEN | EXT4_MAP_BOUNDARY)
+				 EXT4_MAP_UNWRITTEN | EXT4_MAP_BOUNDARY |\
+				 EXT4_MAP_DELAYED)
 
 struct ext4_map_blocks {
 	ext4_fsblk_t m_pblk;
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 0892d0568013..fc69f13cf510 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -4073,9 +4073,10 @@  static void ext4_ext_determine_hole(struct inode *inode,
 	} else if (in_range(map->m_lblk, es.es_lblk, es.es_len)) {
 		/*
 		 * Straddle the beginning of the queried range, it's no
-		 * longer a hole, adjust the length to the delayed extent's
-		 * after map->m_lblk.
+		 * longer a hole, mark it is a delalloc and adjust the
+		 * length to the delayed extent's after map->m_lblk.
 		 */
+		map->m_flags |= EXT4_MAP_DELAYED;
 		len = es.es_lblk + es.es_len - map->m_lblk;
 		goto out;
 	} else {
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 1b5e6409f958..c141bf6d8db2 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -515,6 +515,8 @@  int ext4_map_blocks(handle_t *handle, struct inode *inode,
 			map->m_len = retval;
 		} else if (ext4_es_is_delayed(&es) || ext4_es_is_hole(&es)) {
 			map->m_pblk = 0;
+			map->m_flags |= ext4_es_is_delayed(&es) ?
+					EXT4_MAP_DELAYED : 0;
 			retval = es.es_len - (map->m_lblk - es.es_lblk);
 			if (retval > map->m_len)
 				retval = map->m_len;