[PATCH 1/2] erofs: allow readdir() to be interrupted

[PATCH 1/2] erofs: allow readdir() to be interrupted

[Chao Yu]

In a quick slow device, readdir() may loop for long time in large
directory, let's give a chance to allow it to be interrupted by
userspace.

Signed-off-by: Chao Yu <chao@kernel.org>
---
 fs/erofs/dir.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/fs/erofs/dir.c b/fs/erofs/dir.c
index 2fae209d0274..cff61c5a172b 100644
--- a/fs/erofs/dir.c
+++ b/fs/erofs/dir.c
@@ -58,6 +58,13 @@ static int erofs_readdir(struct file *f, struct dir_context *ctx)
 		struct erofs_dirent *de;
 		unsigned int nameoff, maxsize;
 
+		/* allow readdir() to be interrupted */
+		if (fatal_signal_pending(current)) {
+			err = -ERESTARTSYS;
+			break;
+		}
+		cond_resched();
+
 		de = erofs_bread(&buf, dbstart, true);
 		if (IS_ERR(de)) {
 			erofs_err(sb, "failed to readdir of logical block %llu of nid %llu",
-- 
2.49.0

[PATCH 2/2] erofs: support to readahead dirent blocks in erofs_readdir()

[Chao Yu]

This patch supports to readahead more blocks in erofs_readdir(),
it can enhance performance in large direcotry.

readdir test in a large directory which contains 12000 sub-files.

		files_per_second
Before:		926385.54
After:		2380435.562

Signed-off-by: Chao Yu <chao@kernel.org>
---
 fs/erofs/dir.c      | 8 ++++++++
 fs/erofs/internal.h | 3 +++
 2 files changed, 11 insertions(+)

diff --git a/fs/erofs/dir.c b/fs/erofs/dir.c
index cff61c5a172b..04113851fc0f 100644
--- a/fs/erofs/dir.c
+++ b/fs/erofs/dir.c
@@ -47,8 +47,10 @@ static int erofs_readdir(struct file *f, struct dir_context *ctx)
 	struct inode *dir = file_inode(f);
 	struct erofs_buf buf = __EROFS_BUF_INITIALIZER;
 	struct super_block *sb = dir->i_sb;
+	struct file_ra_state *ra = &f->f_ra;
 	unsigned long bsz = sb->s_blocksize;
 	unsigned int ofs = erofs_blkoff(sb, ctx->pos);
+	unsigned long nr_pages = DIV_ROUND_UP_POW2(dir->i_size, PAGE_SIZE);
 	int err = 0;
 	bool initial = true;
 
@@ -65,6 +67,12 @@ static int erofs_readdir(struct file *f, struct dir_context *ctx)
 		}
 		cond_resched();
 
+		/* readahead blocks to enhance performance in large directory */
+		if (nr_pages - dbstart > 1 && !ra_has_index(ra, dbstart))
+			page_cache_sync_readahead(dir->i_mapping, ra, f,
+				dbstart, min(nr_pages - dbstart,
+				(pgoff_t)MAX_DIR_RA_PAGES));
+
 		de = erofs_bread(&buf, dbstart, true);
 		if (IS_ERR(de)) {
 			erofs_err(sb, "failed to readdir of logical block %llu of nid %llu",
diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
index a32c03a80c70..ef9d1ee8c688 100644
--- a/fs/erofs/internal.h
+++ b/fs/erofs/internal.h
@@ -238,6 +238,9 @@ EROFS_FEATURE_FUNCS(xattr_filter, compat, COMPAT_XATTR_FILTER)
 #define EROFS_I_BL_XATTR_BIT	(BITS_PER_LONG - 1)
 #define EROFS_I_BL_Z_BIT	(BITS_PER_LONG - 2)
 
+/* maximum readahead pages of directory */
+#define MAX_DIR_RA_PAGES	4
+
 struct erofs_inode {
 	erofs_nid_t nid;
 
-- 
2.49.0

Re: [PATCH 1/2] erofs: allow readdir() to be interrupted

[Gao Xiang]

On 2025/7/10 15:36, Chao Yu wrote:
> In a quick slow device, readdir() may loop for long time in large
> directory, let's give a chance to allow it to be interrupted by
> userspace.
> 
> Signed-off-by: Chao Yu <chao@kernel.org>

Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>

> ---
>   fs/erofs/dir.c | 7 +++++++
>   1 file changed, 7 insertions(+)
> 
> diff --git a/fs/erofs/dir.c b/fs/erofs/dir.c
> index 2fae209d0274..cff61c5a172b 100644
> --- a/fs/erofs/dir.c
> +++ b/fs/erofs/dir.c
> @@ -58,6 +58,13 @@ static int erofs_readdir(struct file *f, struct dir_context *ctx)
>   		struct erofs_dirent *de;
>   		unsigned int nameoff, maxsize;
>   
> +		/* allow readdir() to be interrupted */

Hi Chao,

It seems that comment is unnecessary since the following code
is obvious, if you have no objection I will remove this
comment when applying.

Thanks,
Gao Xiang

Re: [PATCH 2/2] erofs: support to readahead dirent blocks in erofs_readdir()

[Gao Xiang]

Hi Chao,

On 2025/7/10 15:36, Chao Yu wrote:
> This patch supports to readahead more blocks in erofs_readdir(),
> it can enhance performance in large direcotry.
> 
> readdir test in a large directory which contains 12000 sub-files.
> 
> 		files_per_second
> Before:		926385.54
> After:		2380435.562
> 
> Signed-off-by: Chao Yu <chao@kernel.org>
> ---
>   fs/erofs/dir.c      | 8 ++++++++
>   fs/erofs/internal.h | 3 +++
>   2 files changed, 11 insertions(+)
> 
> diff --git a/fs/erofs/dir.c b/fs/erofs/dir.c
> index cff61c5a172b..04113851fc0f 100644
> --- a/fs/erofs/dir.c
> +++ b/fs/erofs/dir.c
> @@ -47,8 +47,10 @@ static int erofs_readdir(struct file *f, struct dir_context *ctx)
>   	struct inode *dir = file_inode(f);
>   	struct erofs_buf buf = __EROFS_BUF_INITIALIZER;
>   	struct super_block *sb = dir->i_sb;
> +	struct file_ra_state *ra = &f->f_ra;
>   	unsigned long bsz = sb->s_blocksize;
>   	unsigned int ofs = erofs_blkoff(sb, ctx->pos);
> +	unsigned long nr_pages = DIV_ROUND_UP_POW2(dir->i_size, PAGE_SIZE);
>   	int err = 0;
>   	bool initial = true;
>   
> @@ -65,6 +67,12 @@ static int erofs_readdir(struct file *f, struct dir_context *ctx)
>   		}
>   		cond_resched();
>   
> +		/* readahead blocks to enhance performance in large directory */
> +		if (nr_pages - dbstart > 1 && !ra_has_index(ra, dbstart))
> +			page_cache_sync_readahead(dir->i_mapping, ra, f,
> +				dbstart, min(nr_pages - dbstart,
> +				(pgoff_t)MAX_DIR_RA_PAGES));
> +
>   		de = erofs_bread(&buf, dbstart, true);
>   		if (IS_ERR(de)) {
>   			erofs_err(sb, "failed to readdir of logical block %llu of nid %llu",
> diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
> index a32c03a80c70..ef9d1ee8c688 100644
> --- a/fs/erofs/internal.h
> +++ b/fs/erofs/internal.h
> @@ -238,6 +238,9 @@ EROFS_FEATURE_FUNCS(xattr_filter, compat, COMPAT_XATTR_FILTER)
>   #define EROFS_I_BL_XATTR_BIT	(BITS_PER_LONG - 1)
>   #define EROFS_I_BL_Z_BIT	(BITS_PER_LONG - 2)
>   
> +/* maximum readahead pages of directory */
> +#define MAX_DIR_RA_PAGES	4

Could we set it as a per-sb sysfs configuration for users to config?

Thanks,
Gao Xiang

Re: [PATCH 1/2] erofs: allow readdir() to be interrupted

[Chao Yu]

On 7/10/25 15:41, Gao Xiang wrote:
> 
> 
> On 2025/7/10 15:36, Chao Yu wrote:
>> In a quick slow device, readdir() may loop for long time in large
>> directory, let's give a chance to allow it to be interrupted by
>> userspace.
>>
>> Signed-off-by: Chao Yu <chao@kernel.org>
> 
> Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
> 
>> ---
>>   fs/erofs/dir.c | 7 +++++++
>>   1 file changed, 7 insertions(+)
>>
>> diff --git a/fs/erofs/dir.c b/fs/erofs/dir.c
>> index 2fae209d0274..cff61c5a172b 100644
>> --- a/fs/erofs/dir.c
>> +++ b/fs/erofs/dir.c
>> @@ -58,6 +58,13 @@ static int erofs_readdir(struct file *f, struct dir_context *ctx)
>>           struct erofs_dirent *de;
>>           unsigned int nameoff, maxsize;
>>   +        /* allow readdir() to be interrupted */
> 
> Hi Chao,
> 
> It seems that comment is unnecessary since the following code
> is obvious, if you have no objection I will remove this
> comment when applying.

Xiang, sure, no problem. :)

Thanks,

> 
> Thanks,
> Gao Xiang

Re: [PATCH 2/2] erofs: support to readahead dirent blocks in erofs_readdir()

[Chao Yu]

On 7/10/25 15:46, Gao Xiang wrote:
> Hi Chao,
> 
> On 2025/7/10 15:36, Chao Yu wrote:
>> This patch supports to readahead more blocks in erofs_readdir(),
>> it can enhance performance in large direcotry.
>>
>> readdir test in a large directory which contains 12000 sub-files.
>>
>>         files_per_second
>> Before:        926385.54
>> After:        2380435.562
>>
>> Signed-off-by: Chao Yu <chao@kernel.org>
>> ---
>>   fs/erofs/dir.c      | 8 ++++++++
>>   fs/erofs/internal.h | 3 +++
>>   2 files changed, 11 insertions(+)
>>
>> diff --git a/fs/erofs/dir.c b/fs/erofs/dir.c
>> index cff61c5a172b..04113851fc0f 100644
>> --- a/fs/erofs/dir.c
>> +++ b/fs/erofs/dir.c
>> @@ -47,8 +47,10 @@ static int erofs_readdir(struct file *f, struct dir_context *ctx)
>>       struct inode *dir = file_inode(f);
>>       struct erofs_buf buf = __EROFS_BUF_INITIALIZER;
>>       struct super_block *sb = dir->i_sb;
>> +    struct file_ra_state *ra = &f->f_ra;
>>       unsigned long bsz = sb->s_blocksize;
>>       unsigned int ofs = erofs_blkoff(sb, ctx->pos);
>> +    unsigned long nr_pages = DIV_ROUND_UP_POW2(dir->i_size, PAGE_SIZE);
>>       int err = 0;
>>       bool initial = true;
>>   @@ -65,6 +67,12 @@ static int erofs_readdir(struct file *f, struct dir_context *ctx)
>>           }
>>           cond_resched();
>>   +        /* readahead blocks to enhance performance in large directory */
>> +        if (nr_pages - dbstart > 1 && !ra_has_index(ra, dbstart))
>> +            page_cache_sync_readahead(dir->i_mapping, ra, f,
>> +                dbstart, min(nr_pages - dbstart,
>> +                (pgoff_t)MAX_DIR_RA_PAGES));
>> +
>>           de = erofs_bread(&buf, dbstart, true);
>>           if (IS_ERR(de)) {
>>               erofs_err(sb, "failed to readdir of logical block %llu of nid %llu",
>> diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
>> index a32c03a80c70..ef9d1ee8c688 100644
>> --- a/fs/erofs/internal.h
>> +++ b/fs/erofs/internal.h
>> @@ -238,6 +238,9 @@ EROFS_FEATURE_FUNCS(xattr_filter, compat, COMPAT_XATTR_FILTER)
>>   #define EROFS_I_BL_XATTR_BIT    (BITS_PER_LONG - 1)
>>   #define EROFS_I_BL_Z_BIT    (BITS_PER_LONG - 2)
>>   +/* maximum readahead pages of directory */
>> +#define MAX_DIR_RA_PAGES    4
> 
> Could we set it as a per-sb sysfs configuration for users to config?

Xiang,

Oh, that will be better, how about introducing new sysfs in separated patch?

Thanks,

> 
> Thanks,
> Gao Xiang

Re: [PATCH 2/2] erofs: support to readahead dirent blocks in erofs_readdir()

[Gao Xiang]

On 2025/7/10 15:59, Chao Yu wrote:
> On 7/10/25 15:46, Gao Xiang wrote:
>> Hi Chao,
>>
>> On 2025/7/10 15:36, Chao Yu wrote:
>>> This patch supports to readahead more blocks in erofs_readdir(),
>>> it can enhance performance in large direcotry.
>>>
>>> readdir test in a large directory which contains 12000 sub-files.
>>>
>>>          files_per_second
>>> Before:        926385.54
>>> After:        2380435.562
>>>
>>> Signed-off-by: Chao Yu <chao@kernel.org>
>>> ---
>>>    fs/erofs/dir.c      | 8 ++++++++
>>>    fs/erofs/internal.h | 3 +++
>>>    2 files changed, 11 insertions(+)
>>>
>>> diff --git a/fs/erofs/dir.c b/fs/erofs/dir.c
>>> index cff61c5a172b..04113851fc0f 100644
>>> --- a/fs/erofs/dir.c
>>> +++ b/fs/erofs/dir.c
>>> @@ -47,8 +47,10 @@ static int erofs_readdir(struct file *f, struct dir_context *ctx)
>>>        struct inode *dir = file_inode(f);
>>>        struct erofs_buf buf = __EROFS_BUF_INITIALIZER;
>>>        struct super_block *sb = dir->i_sb;
>>> +    struct file_ra_state *ra = &f->f_ra;
>>>        unsigned long bsz = sb->s_blocksize;
>>>        unsigned int ofs = erofs_blkoff(sb, ctx->pos);
>>> +    unsigned long nr_pages = DIV_ROUND_UP_POW2(dir->i_size, PAGE_SIZE);
>>>        int err = 0;
>>>        bool initial = true;
>>>    @@ -65,6 +67,12 @@ static int erofs_readdir(struct file *f, struct dir_context *ctx)
>>>            }
>>>            cond_resched();
>>>    +        /* readahead blocks to enhance performance in large directory */
>>> +        if (nr_pages - dbstart > 1 && !ra_has_index(ra, dbstart))
>>> +            page_cache_sync_readahead(dir->i_mapping, ra, f,
>>> +                dbstart, min(nr_pages - dbstart,
>>> +                (pgoff_t)MAX_DIR_RA_PAGES));
>>> +
>>>            de = erofs_bread(&buf, dbstart, true);
>>>            if (IS_ERR(de)) {
>>>                erofs_err(sb, "failed to readdir of logical block %llu of nid %llu",
>>> diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
>>> index a32c03a80c70..ef9d1ee8c688 100644
>>> --- a/fs/erofs/internal.h
>>> +++ b/fs/erofs/internal.h
>>> @@ -238,6 +238,9 @@ EROFS_FEATURE_FUNCS(xattr_filter, compat, COMPAT_XATTR_FILTER)
>>>    #define EROFS_I_BL_XATTR_BIT    (BITS_PER_LONG - 1)
>>>    #define EROFS_I_BL_Z_BIT    (BITS_PER_LONG - 2)
>>>    +/* maximum readahead pages of directory */
>>> +#define MAX_DIR_RA_PAGES    4
>>
>> Could we set it as a per-sb sysfs configuration for users to config?
> 
> Xiang,
> 
> Oh, that will be better, how about introducing new sysfs in separated patch?

Hi Chao,

Thanks for your interest but in that case it could cause some bisect
issue anyway, could we just use one patch to add this optimization
for slow devices?

Thanks,
Gao Xiang

> 
> Thanks,
> 
>>
>> Thanks,
>> Gao Xiang
> 

Re: [PATCH 2/2] erofs: support to readahead dirent blocks in erofs_readdir()

[Chao Yu]

On 7/10/25 16:04, Gao Xiang wrote:
> 
> 
> On 2025/7/10 15:59, Chao Yu wrote:
>> On 7/10/25 15:46, Gao Xiang wrote:
>>> Hi Chao,
>>>
>>> On 2025/7/10 15:36, Chao Yu wrote:
>>>> This patch supports to readahead more blocks in erofs_readdir(),
>>>> it can enhance performance in large direcotry.
>>>>
>>>> readdir test in a large directory which contains 12000 sub-files.
>>>>
>>>>          files_per_second
>>>> Before:        926385.54
>>>> After:        2380435.562
>>>>
>>>> Signed-off-by: Chao Yu <chao@kernel.org>
>>>> ---
>>>>    fs/erofs/dir.c      | 8 ++++++++
>>>>    fs/erofs/internal.h | 3 +++
>>>>    2 files changed, 11 insertions(+)
>>>>
>>>> diff --git a/fs/erofs/dir.c b/fs/erofs/dir.c
>>>> index cff61c5a172b..04113851fc0f 100644
>>>> --- a/fs/erofs/dir.c
>>>> +++ b/fs/erofs/dir.c
>>>> @@ -47,8 +47,10 @@ static int erofs_readdir(struct file *f, struct dir_context *ctx)
>>>>        struct inode *dir = file_inode(f);
>>>>        struct erofs_buf buf = __EROFS_BUF_INITIALIZER;
>>>>        struct super_block *sb = dir->i_sb;
>>>> +    struct file_ra_state *ra = &f->f_ra;
>>>>        unsigned long bsz = sb->s_blocksize;
>>>>        unsigned int ofs = erofs_blkoff(sb, ctx->pos);
>>>> +    unsigned long nr_pages = DIV_ROUND_UP_POW2(dir->i_size, PAGE_SIZE);
>>>>        int err = 0;
>>>>        bool initial = true;
>>>>    @@ -65,6 +67,12 @@ static int erofs_readdir(struct file *f, struct dir_context *ctx)
>>>>            }
>>>>            cond_resched();
>>>>    +        /* readahead blocks to enhance performance in large directory */
>>>> +        if (nr_pages - dbstart > 1 && !ra_has_index(ra, dbstart))
>>>> +            page_cache_sync_readahead(dir->i_mapping, ra, f,
>>>> +                dbstart, min(nr_pages - dbstart,
>>>> +                (pgoff_t)MAX_DIR_RA_PAGES));
>>>> +
>>>>            de = erofs_bread(&buf, dbstart, true);
>>>>            if (IS_ERR(de)) {
>>>>                erofs_err(sb, "failed to readdir of logical block %llu of nid %llu",
>>>> diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
>>>> index a32c03a80c70..ef9d1ee8c688 100644
>>>> --- a/fs/erofs/internal.h
>>>> +++ b/fs/erofs/internal.h
>>>> @@ -238,6 +238,9 @@ EROFS_FEATURE_FUNCS(xattr_filter, compat, COMPAT_XATTR_FILTER)
>>>>    #define EROFS_I_BL_XATTR_BIT    (BITS_PER_LONG - 1)
>>>>    #define EROFS_I_BL_Z_BIT    (BITS_PER_LONG - 2)
>>>>    +/* maximum readahead pages of directory */
>>>> +#define MAX_DIR_RA_PAGES    4
>>>
>>> Could we set it as a per-sb sysfs configuration for users to config?
>>
>> Xiang,
>>
>> Oh, that will be better, how about introducing new sysfs in separated patch?
> 
> Hi Chao,
> 
> Thanks for your interest but in that case it could cause some bisect
> issue anyway, could we just use one patch to add this optimization
> for slow devices?

Xiang,

Yeah, one patch includes all these looks fine to me, anyway, let me update v2.

Thanks,

> 
> Thanks,
> Gao Xiang
> 
>>
>> Thanks,
>>
>>>
>>> Thanks,
>>> Gao Xiang
>>
>