In f2fs_precache_extents(), For large files, It requires reading many
node blocks. Instead of reading each node block with synchronous I/O,
this patch applies readahead so that node blocks can be fetched in
advance.

It reduces the overhead of repeated sync reads and improves efficiency
when precaching extents of large files.

I created a file with the same largest extent and executed the test.
For this experiment, I set the file's largest extent with an offset of 0
and a size of 1GB. I configured the remaining area with 100MB extents.

5GB test file:
dd if=/dev/urandom of=test1 bs=1m count=5120
cp test1 test2
fsync test1
dd if=test1 of=test2 bs=1m skip=1024 seek=1024 count=100 conv=notrunc
dd if=test1 of=test2 bs=1m skip=1224 seek=1224 count=100 conv=notrunc
...
dd if=test1 of=test2 bs=1m skip=5024 seek=5024 count=100 conv=notrunc
reboot

I also created 10GB and 20GB files with large extents using the same
method.

ioctl(F2FS_IOC_PRECACHE_EXTENTS) test results are as follows:
  +-----------+---------+---------+-----------+
  | File size | Before  | After   | Reduction |
  +-----------+---------+---------+-----------+
  | 5GB       | 101.8ms | 37.0ms  | 72.1%     |
  | 10GB      | 222.9ms | 56.0ms  | 74.9%     |
  | 20GB      | 446.2ms | 116.4ms | 73.9%     |
  +-----------+---------+---------+-----------+
Tested on a 256GB mobile device with an SM8750 chipset.

Reviewed-by: Sungjong Seo <sj1557.seo@samsung.com>
Reviewed-by: Sunmin Jeong <s_min.jeong@samsung.com>
Signed-off-by: Yunji Kang <yunji0.kang@samsung.com>
---
v2:
 - Modify the readahead condition check routine for better code
readability.
 - Update the title from 'node block' to 'node blocks'.

v3:
 - Bug fix to allow more node pages to be readahead.
 - Updated with test results.

 fs/f2fs/data.c | 3 +++
 fs/f2fs/f2fs.h | 1 +
 fs/f2fs/node.c | 4 +++-
 3 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 7961e0ddfca3..ab3117e3b24a 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -1572,6 +1572,9 @@ int f2fs_map_blocks(struct inode *inode, struct f2fs_map_blocks *map, int flag)
 	pgofs =	(pgoff_t)map->m_lblk;
 	end = pgofs + maxblocks;
 
+	if (flag == F2FS_GET_BLOCK_PRECACHE)
+		mode = LOOKUP_NODE_PRECACHE;
+
 next_dnode:
 	if (map->m_may_create) {
 		if (f2fs_lfs_mode(sbi))
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 9d3bc9633c1d..3ce41528d48e 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -651,6 +651,7 @@ enum {
 					 * look up a node with readahead called
 					 * by get_data_block.
 					 */
+	LOOKUP_NODE_PRECACHE,		/* look up a node for F2FS_GET_BLOCK_PRECACHE */
 };
 
 #define DEFAULT_RETRY_IO_COUNT	8	/* maximum retry read IO or flush count */
diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
index 4254db453b2d..63e9ee7ab911 100644
--- a/fs/f2fs/node.c
+++ b/fs/f2fs/node.c
@@ -860,7 +860,9 @@ int f2fs_get_dnode_of_data(struct dnode_of_data *dn, pgoff_t index, int mode)
 			set_nid(parent, offset[i - 1], nids[i], i == 1);
 			f2fs_alloc_nid_done(sbi, nids[i]);
 			done = true;
-		} else if (mode == LOOKUP_NODE_RA && i == level && level > 1) {
+		} else if ((mode == LOOKUP_NODE_RA ||
+                (mode == LOOKUP_NODE_PRECACHE))
+                && i == level && level > 1) {
 			nfolio[i] = f2fs_get_node_folio_ra(parent, offset[i - 1]);
 			if (IS_ERR(nfolio[i])) {
 				err = PTR_ERR(nfolio[i]);
-- 
2.34.1

On 9/24/25 13:58, Yunji Kang wrote:
> In f2fs_precache_extents(), For large files, It requires reading many
> node blocks. Instead of reading each node block with synchronous I/O,
> this patch applies readahead so that node blocks can be fetched in
> advance.
> 
> It reduces the overhead of repeated sync reads and improves efficiency
> when precaching extents of large files.
> 
> I created a file with the same largest extent and executed the test.
> For this experiment, I set the file's largest extent with an offset of 0
> and a size of 1GB. I configured the remaining area with 100MB extents.
> 
> 5GB test file:
> dd if=/dev/urandom of=test1 bs=1m count=5120
> cp test1 test2
> fsync test1
> dd if=test1 of=test2 bs=1m skip=1024 seek=1024 count=100 conv=notrunc
> dd if=test1 of=test2 bs=1m skip=1224 seek=1224 count=100 conv=notrunc
> ...
> dd if=test1 of=test2 bs=1m skip=5024 seek=5024 count=100 conv=notrunc
> reboot
> 
> I also created 10GB and 20GB files with large extents using the same
> method.
> 
> ioctl(F2FS_IOC_PRECACHE_EXTENTS) test results are as follows:
>   +-----------+---------+---------+-----------+
>   | File size | Before  | After   | Reduction |
>   +-----------+---------+---------+-----------+
>   | 5GB       | 101.8ms | 37.0ms  | 72.1%     |
>   | 10GB      | 222.9ms | 56.0ms  | 74.9%     |
>   | 20GB      | 446.2ms | 116.4ms | 73.9%     |
>   +-----------+---------+---------+-----------+
> Tested on a 256GB mobile device with an SM8750 chipset.
> 
> Reviewed-by: Sungjong Seo <sj1557.seo@samsung.com>
> Reviewed-by: Sunmin Jeong <s_min.jeong@samsung.com>
> Signed-off-by: Yunji Kang <yunji0.kang@samsung.com>
> ---
> v2:
>  - Modify the readahead condition check routine for better code
> readability.
>  - Update the title from 'node block' to 'node blocks'.
> 
> v3:
>  - Bug fix to allow more node pages to be readahead.
>  - Updated with test results.
> 
>  fs/f2fs/data.c | 3 +++
>  fs/f2fs/f2fs.h | 1 +
>  fs/f2fs/node.c | 4 +++-
>  3 files changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> index 7961e0ddfca3..ab3117e3b24a 100644
> --- a/fs/f2fs/data.c
> +++ b/fs/f2fs/data.c
> @@ -1572,6 +1572,9 @@ int f2fs_map_blocks(struct inode *inode, struct f2fs_map_blocks *map, int flag)
>  	pgofs =	(pgoff_t)map->m_lblk;
>  	end = pgofs + maxblocks;
>  
> +	if (flag == F2FS_GET_BLOCK_PRECACHE)
> +		mode = LOOKUP_NODE_PRECACHE;

If trigger condition of LOOKUP_NODE_RA and LOOKUP_NODE_PRECACHE is the same,
What about?

	if (flag == F2FS_GET_BLOCK_PRECACHE)
		mode = LOOKUP_NODE_RA;

Thanks,

> +
>  next_dnode:
>  	if (map->m_may_create) {
>  		if (f2fs_lfs_mode(sbi))
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index 9d3bc9633c1d..3ce41528d48e 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -651,6 +651,7 @@ enum {
>  					 * look up a node with readahead called
>  					 * by get_data_block.
>  					 */
> +	LOOKUP_NODE_PRECACHE,		/* look up a node for F2FS_GET_BLOCK_PRECACHE */
>  };
>  
>  #define DEFAULT_RETRY_IO_COUNT	8	/* maximum retry read IO or flush count */
> diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
> index 4254db453b2d..63e9ee7ab911 100644
> --- a/fs/f2fs/node.c
> +++ b/fs/f2fs/node.c
> @@ -860,7 +860,9 @@ int f2fs_get_dnode_of_data(struct dnode_of_data *dn, pgoff_t index, int mode)
>  			set_nid(parent, offset[i - 1], nids[i], i == 1);
>  			f2fs_alloc_nid_done(sbi, nids[i]);
>  			done = true;
> -		} else if (mode == LOOKUP_NODE_RA && i == level && level > 1) {
> +		} else if ((mode == LOOKUP_NODE_RA ||
> +                (mode == LOOKUP_NODE_PRECACHE))
> +                && i == level && level > 1) {
>  			nfolio[i] = f2fs_get_node_folio_ra(parent, offset[i - 1]);
>  			if (IS_ERR(nfolio[i])) {
>  				err = PTR_ERR(nfolio[i]);

>On 9/24/25 13:58, Yunji Kang wrote:
>> In f2fs_precache_extents(), For large files, It requires reading many
>> node blocks. Instead of reading each node block with synchronous I/O,
>> this patch applies readahead so that node blocks can be fetched in
>> advance.
>> 
>> It reduces the overhead of repeated sync reads and improves efficiency
>> when precaching extents of large files.
>> 
>> I created a file with the same largest extent and executed the test.
>> For this experiment, I set the file's largest extent with an offset of 0
>> and a size of 1GB. I configured the remaining area with 100MB extents.
>> 
>> 5GB test file:
>> dd if=/dev/urandom of=test1 bs=1m count=5120
>> cp test1 test2
>> fsync test1
>> dd if=test1 of=test2 bs=1m skip=1024 seek=1024 count=100 conv=notrunc
>> dd if=test1 of=test2 bs=1m skip=1224 seek=1224 count=100 conv=notrunc
>> ...
>> dd if=test1 of=test2 bs=1m skip=5024 seek=5024 count=100 conv=notrunc
>> reboot
>> 
>> I also created 10GB and 20GB files with large extents using the same
>> method.
>> 
>> ioctl(F2FS_IOC_PRECACHE_EXTENTS) test results are as follows:
>>   +-----------+---------+---------+-----------+
>>   | File size | Before  | After   | Reduction |
>>   +-----------+---------+---------+-----------+
>>   | 5GB       | 101.8ms | 37.0ms  | 72.1%     |
>>   | 10GB      | 222.9ms | 56.0ms  | 74.9%     |
>>   | 20GB      | 446.2ms | 116.4ms | 73.9%     |
>>   +-----------+---------+---------+-----------+
>> Tested on a 256GB mobile device with an SM8750 chipset.
>> 
>> Reviewed-by: Sungjong Seo <sj1557.seo@samsung.com>
>> Reviewed-by: Sunmin Jeong <s_min.jeong@samsung.com>
>> Signed-off-by: Yunji Kang <yunji0.kang@samsung.com>
>> ---
>> v2:
>>  - Modify the readahead condition check routine for better code
>> readability.
>>  - Update the title from 'node block' to 'node blocks'.
>> 
>> v3:
>>  - Bug fix to allow more node pages to be readahead.
>>  - Updated with test results.
>> 
>>  fs/f2fs/data.c | 3 +++
>>  fs/f2fs/f2fs.h | 1 +
>>  fs/f2fs/node.c | 4 +++-
>>  3 files changed, 7 insertions(+), 1 deletion(-)
>> 
>> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
>> index 7961e0ddfca3..ab3117e3b24a 100644
>> --- a/fs/f2fs/data.c
>> +++ b/fs/f2fs/data.c
>> @@ -1572,6 +1572,9 @@ int f2fs_map_blocks(struct inode *inode, struct f2fs_map_blocks *map, int flag)
>>  	pgofs =	(pgoff_t)map->m_lblk;
>>  	end = pgofs + maxblocks;
>>  
>> +	if (flag == F2FS_GET_BLOCK_PRECACHE)
>> +		mode = LOOKUP_NODE_PRECACHE;
>
>If trigger condition of LOOKUP_NODE_RA and LOOKUP_NODE_PRECACHE is the same,
>What about?
>
>	if (flag == F2FS_GET_BLOCK_PRECACHE)
>		mode = LOOKUP_NODE_RA;
>
>Thanks,

Hi Yunji and Chao,
I think so, we can directly use LOOKUP_NODE_RA for precache extents.
BTW, maybe there are more cases that LOOKUP_NODE_RA will be better? Like
defragment/compress(need to call __f2fs_cluster_blocks() ) ioctl..


>> +
>>  next_dnode:
>>  	if (map->m_may_create) {
>>  		if (f2fs_lfs_mode(sbi))
>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
>> index 9d3bc9633c1d..3ce41528d48e 100644
>> --- a/fs/f2fs/f2fs.h
>> +++ b/fs/f2fs/f2fs.h
>> @@ -651,6 +651,7 @@ enum {
>>  					 * look up a node with readahead called
>>  					 * by get_data_block.
>>  					 */
>> +	LOOKUP_NODE_PRECACHE,		/* look up a node for F2FS_GET_BLOCK_PRECACHE */
>>  };
>>  
>>  #define DEFAULT_RETRY_IO_COUNT	8	/* maximum retry read IO or flush count */
>> diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
>> index 4254db453b2d..63e9ee7ab911 100644
>> --- a/fs/f2fs/node.c
>> +++ b/fs/f2fs/node.c
>> @@ -860,7 +860,9 @@ int f2fs_get_dnode_of_data(struct dnode_of_data *dn, pgoff_t index, int mode)
>>  			set_nid(parent, offset[i - 1], nids[i], i == 1);
>>  			f2fs_alloc_nid_done(sbi, nids[i]);
>>  			done = true;
>> -		} else if (mode == LOOKUP_NODE_RA && i == level && level > 1) {
>> +		} else if ((mode == LOOKUP_NODE_RA ||
>> +                (mode == LOOKUP_NODE_PRECACHE))
>> +                && i == level && level > 1) {
>>  			nfolio[i] = f2fs_get_node_folio_ra(parent, offset[i - 1]);
>>  			if (IS_ERR(nfolio[i])) {
>>  				err = PTR_ERR(nfolio[i]);

On 9/24/25 14:53, wangzijie wrote:
>> On 9/24/25 13:58, Yunji Kang wrote:
>>> In f2fs_precache_extents(), For large files, It requires reading many
>>> node blocks. Instead of reading each node block with synchronous I/O,
>>> this patch applies readahead so that node blocks can be fetched in
>>> advance.
>>>
>>> It reduces the overhead of repeated sync reads and improves efficiency
>>> when precaching extents of large files.
>>>
>>> I created a file with the same largest extent and executed the test.
>>> For this experiment, I set the file's largest extent with an offset of 0
>>> and a size of 1GB. I configured the remaining area with 100MB extents.
>>>
>>> 5GB test file:
>>> dd if=/dev/urandom of=test1 bs=1m count=5120
>>> cp test1 test2
>>> fsync test1
>>> dd if=test1 of=test2 bs=1m skip=1024 seek=1024 count=100 conv=notrunc
>>> dd if=test1 of=test2 bs=1m skip=1224 seek=1224 count=100 conv=notrunc
>>> ...
>>> dd if=test1 of=test2 bs=1m skip=5024 seek=5024 count=100 conv=notrunc
>>> reboot
>>>
>>> I also created 10GB and 20GB files with large extents using the same
>>> method.
>>>
>>> ioctl(F2FS_IOC_PRECACHE_EXTENTS) test results are as follows:
>>>   +-----------+---------+---------+-----------+
>>>   | File size | Before  | After   | Reduction |
>>>   +-----------+---------+---------+-----------+
>>>   | 5GB       | 101.8ms | 37.0ms  | 72.1%     |
>>>   | 10GB      | 222.9ms | 56.0ms  | 74.9%     |
>>>   | 20GB      | 446.2ms | 116.4ms | 73.9%     |
>>>   +-----------+---------+---------+-----------+
>>> Tested on a 256GB mobile device with an SM8750 chipset.
>>>
>>> Reviewed-by: Sungjong Seo <sj1557.seo@samsung.com>
>>> Reviewed-by: Sunmin Jeong <s_min.jeong@samsung.com>
>>> Signed-off-by: Yunji Kang <yunji0.kang@samsung.com>
>>> ---
>>> v2:
>>>  - Modify the readahead condition check routine for better code
>>> readability.
>>>  - Update the title from 'node block' to 'node blocks'.
>>>
>>> v3:
>>>  - Bug fix to allow more node pages to be readahead.
>>>  - Updated with test results.
>>>
>>>  fs/f2fs/data.c | 3 +++
>>>  fs/f2fs/f2fs.h | 1 +
>>>  fs/f2fs/node.c | 4 +++-
>>>  3 files changed, 7 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
>>> index 7961e0ddfca3..ab3117e3b24a 100644
>>> --- a/fs/f2fs/data.c
>>> +++ b/fs/f2fs/data.c
>>> @@ -1572,6 +1572,9 @@ int f2fs_map_blocks(struct inode *inode, struct f2fs_map_blocks *map, int flag)
>>>  	pgofs =	(pgoff_t)map->m_lblk;
>>>  	end = pgofs + maxblocks;
>>>  
>>> +	if (flag == F2FS_GET_BLOCK_PRECACHE)
>>> +		mode = LOOKUP_NODE_PRECACHE;
>>
>> If trigger condition of LOOKUP_NODE_RA and LOOKUP_NODE_PRECACHE is the same,
>> What about?
>>
>> 	if (flag == F2FS_GET_BLOCK_PRECACHE)
>> 		mode = LOOKUP_NODE_RA;
>>
>> Thanks,
> 
> Hi Yunji and Chao,
> I think so, we can directly use LOOKUP_NODE_RA for precache extents.
> BTW, maybe there are more cases that LOOKUP_NODE_RA will be better? Like
> defragment/compress(need to call __f2fs_cluster_blocks() ) ioctl..

Yeah, we can have a try to check the benefits. :)

Thaks,

> 
> 
>>> +
>>>  next_dnode:
>>>  	if (map->m_may_create) {
>>>  		if (f2fs_lfs_mode(sbi))
>>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
>>> index 9d3bc9633c1d..3ce41528d48e 100644
>>> --- a/fs/f2fs/f2fs.h
>>> +++ b/fs/f2fs/f2fs.h
>>> @@ -651,6 +651,7 @@ enum {
>>>  					 * look up a node with readahead called
>>>  					 * by get_data_block.
>>>  					 */
>>> +	LOOKUP_NODE_PRECACHE,		/* look up a node for F2FS_GET_BLOCK_PRECACHE */
>>>  };
>>>  
>>>  #define DEFAULT_RETRY_IO_COUNT	8	/* maximum retry read IO or flush count */
>>> diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
>>> index 4254db453b2d..63e9ee7ab911 100644
>>> --- a/fs/f2fs/node.c
>>> +++ b/fs/f2fs/node.c
>>> @@ -860,7 +860,9 @@ int f2fs_get_dnode_of_data(struct dnode_of_data *dn, pgoff_t index, int mode)
>>>  			set_nid(parent, offset[i - 1], nids[i], i == 1);
>>>  			f2fs_alloc_nid_done(sbi, nids[i]);
>>>  			done = true;
>>> -		} else if (mode == LOOKUP_NODE_RA && i == level && level > 1) {
>>> +		} else if ((mode == LOOKUP_NODE_RA ||
>>> +                (mode == LOOKUP_NODE_PRECACHE))
>>> +                && i == level && level > 1) {
>>>  			nfolio[i] = f2fs_get_node_folio_ra(parent, offset[i - 1]);
>>>  			if (IS_ERR(nfolio[i])) {
>>>  				err = PTR_ERR(nfolio[i]);