From: Prasad Singamsetty <prasad.singamsetty@oracle.com>
Extend statx system call to return additional info for atomic write support
support for a file.
Helper function generic_fill_statx_atomic_writes() can be used by FSes to
fill in the relevant statx fields.
Signed-off-by: Prasad Singamsetty <prasad.singamsetty@oracle.com>
#jpg: relocate bdev support to another patch
Signed-off-by: John Garry <john.g.garry@oracle.com>
---
fs/stat.c | 34 ++++++++++++++++++++++++++++++++++
include/linux/fs.h | 3 +++
include/linux/stat.h | 3 +++
include/uapi/linux/stat.h | 9 ++++++++-
4 files changed, 48 insertions(+), 1 deletion(-)
diff --git a/fs/stat.c b/fs/stat.c
index 77cdc69eb422..522787a4ab6a 100644
--- a/fs/stat.c
+++ b/fs/stat.c
@@ -89,6 +89,37 @@ void generic_fill_statx_attr(struct inode *inode, struct kstat *stat)
}
EXPORT_SYMBOL(generic_fill_statx_attr);
+/**
+ * generic_fill_statx_atomic_writes - Fill in the atomic writes statx attributes
+ * @stat: Where to fill in the attribute flags
+ * @unit_min: Minimum supported atomic write length
+ * @unit_max: Maximum supported atomic write length
+ *
+ * Fill in the STATX{_ATTR}_WRITE_ATOMIC flags in the kstat structure from
+ * atomic write unit_min and unit_max values.
+ */
+void generic_fill_statx_atomic_writes(struct kstat *stat,
+ unsigned int unit_min,
+ unsigned int unit_max)
+{
+ /* Confirm that the request type is known */
+ stat->result_mask |= STATX_WRITE_ATOMIC;
+
+ /* Confirm that the file attribute type is known */
+ stat->attributes_mask |= STATX_ATTR_WRITE_ATOMIC;
+
+ if (unit_min) {
+ stat->atomic_write_unit_min = unit_min;
+ stat->atomic_write_unit_max = unit_max;
+ /* Initially only allow 1x segment */
+ stat->atomic_write_segments_max = 1;
+
+ /* Confirm atomic writes are actually supported */
+ stat->attributes |= STATX_ATTR_WRITE_ATOMIC;
+ }
+}
+EXPORT_SYMBOL(generic_fill_statx_atomic_writes);
+
/**
* vfs_getattr_nosec - getattr without security checks
* @path: file to get attributes from
@@ -658,6 +689,9 @@ cp_statx(const struct kstat *stat, struct statx __user *buffer)
tmp.stx_mnt_id = stat->mnt_id;
tmp.stx_dio_mem_align = stat->dio_mem_align;
tmp.stx_dio_offset_align = stat->dio_offset_align;
+ tmp.stx_atomic_write_unit_min = stat->atomic_write_unit_min;
+ tmp.stx_atomic_write_unit_max = stat->atomic_write_unit_max;
+ tmp.stx_atomic_write_segments_max = stat->atomic_write_segments_max;
return copy_to_user(buffer, &tmp, sizeof(tmp)) ? -EFAULT : 0;
}
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 7271640fd600..531140a7e27a 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -3167,6 +3167,9 @@ extern const struct inode_operations page_symlink_inode_operations;
extern void kfree_link(void *);
void generic_fillattr(struct mnt_idmap *, u32, struct inode *, struct kstat *);
void generic_fill_statx_attr(struct inode *inode, struct kstat *stat);
+void generic_fill_statx_atomic_writes(struct kstat *stat,
+ unsigned int unit_min,
+ unsigned int unit_max);
extern int vfs_getattr_nosec(const struct path *, struct kstat *, u32, unsigned int);
extern int vfs_getattr(const struct path *, struct kstat *, u32, unsigned int);
void __inode_add_bytes(struct inode *inode, loff_t bytes);
diff --git a/include/linux/stat.h b/include/linux/stat.h
index 52150570d37a..2c5e2b8c6559 100644
--- a/include/linux/stat.h
+++ b/include/linux/stat.h
@@ -53,6 +53,9 @@ struct kstat {
u32 dio_mem_align;
u32 dio_offset_align;
u64 change_cookie;
+ u32 atomic_write_unit_min;
+ u32 atomic_write_unit_max;
+ u32 atomic_write_segments_max;
};
/* These definitions are internal to the kernel for now. Mainly used by nfsd. */
diff --git a/include/uapi/linux/stat.h b/include/uapi/linux/stat.h
index 2f2ee82d5517..c0e8e10d1de6 100644
--- a/include/uapi/linux/stat.h
+++ b/include/uapi/linux/stat.h
@@ -127,7 +127,12 @@ struct statx {
__u32 stx_dio_mem_align; /* Memory buffer alignment for direct I/O */
__u32 stx_dio_offset_align; /* File offset alignment for direct I/O */
/* 0xa0 */
- __u64 __spare3[12]; /* Spare space for future expansion */
+ __u32 stx_atomic_write_unit_min;
+ __u32 stx_atomic_write_unit_max;
+ __u32 stx_atomic_write_segments_max;
+ __u32 __spare1;
+ /* 0xb0 */
+ __u64 __spare3[10]; /* Spare space for future expansion */
/* 0x100 */
};
@@ -155,6 +160,7 @@ struct statx {
#define STATX_MNT_ID 0x00001000U /* Got stx_mnt_id */
#define STATX_DIOALIGN 0x00002000U /* Want/got direct I/O alignment info */
#define STATX_MNT_ID_UNIQUE 0x00004000U /* Want/got extended stx_mount_id */
+#define STATX_WRITE_ATOMIC 0x00008000U /* Want/got atomic_write_* fields */
#define STATX__RESERVED 0x80000000U /* Reserved for future struct statx expansion */
@@ -190,6 +196,7 @@ struct statx {
#define STATX_ATTR_MOUNT_ROOT 0x00002000 /* Root of a mount */
#define STATX_ATTR_VERITY 0x00100000 /* [I] Verity protected file */
#define STATX_ATTR_DAX 0x00200000 /* File is currently in DAX state */
+#define STATX_ATTR_WRITE_ATOMIC 0x00400000 /* File supports atomic write operations */
#endif /* _UAPI_LINUX_STAT_H */
--
2.31.1John Garry <john.g.garry@oracle.com> writes:
> From: Prasad Singamsetty <prasad.singamsetty@oracle.com>
>
> Extend statx system call to return additional info for atomic write support
> support for a file.
>
> Helper function generic_fill_statx_atomic_writes() can be used by FSes to
> fill in the relevant statx fields.
>
> Signed-off-by: Prasad Singamsetty <prasad.singamsetty@oracle.com>
> #jpg: relocate bdev support to another patch
^^^ miss maybe?
> Signed-off-by: John Garry <john.g.garry@oracle.com>
> ---
> fs/stat.c | 34 ++++++++++++++++++++++++++++++++++
> include/linux/fs.h | 3 +++
> include/linux/stat.h | 3 +++
> include/uapi/linux/stat.h | 9 ++++++++-
> 4 files changed, 48 insertions(+), 1 deletion(-)
>
> diff --git a/fs/stat.c b/fs/stat.c
> index 77cdc69eb422..522787a4ab6a 100644
> --- a/fs/stat.c
> +++ b/fs/stat.c
> @@ -89,6 +89,37 @@ void generic_fill_statx_attr(struct inode *inode, struct kstat *stat)
> }
> EXPORT_SYMBOL(generic_fill_statx_attr);
>
> +/**
> + * generic_fill_statx_atomic_writes - Fill in the atomic writes statx attributes
> + * @stat: Where to fill in the attribute flags
> + * @unit_min: Minimum supported atomic write length
+ * @unit_min: Minimum supported atomic write length in bytes
> + * @unit_max: Maximum supported atomic write length
+ * @unit_max: Maximum supported atomic write length in bytes
mentioning unit of the length might be useful here.
> + *
> + * Fill in the STATX{_ATTR}_WRITE_ATOMIC flags in the kstat structure from
> + * atomic write unit_min and unit_max values.
> + */
> +void generic_fill_statx_atomic_writes(struct kstat *stat,
> + unsigned int unit_min,
This (unit_min) can still go above in the same line.
> + unsigned int unit_max)
> +{
> + /* Confirm that the request type is known */
> + stat->result_mask |= STATX_WRITE_ATOMIC;
> +
> + /* Confirm that the file attribute type is known */
> + stat->attributes_mask |= STATX_ATTR_WRITE_ATOMIC;
> +
> + if (unit_min) {
> + stat->atomic_write_unit_min = unit_min;
> + stat->atomic_write_unit_max = unit_max;
> + /* Initially only allow 1x segment */
> + stat->atomic_write_segments_max = 1;
Please log info about this in commit message about where this limit came
from? Is it since we only support ubuf (which IIUC, only supports 1
segment)? Later when we will add support for iovec, this limit can be
lifted?
> +
> + /* Confirm atomic writes are actually supported */
> + stat->attributes |= STATX_ATTR_WRITE_ATOMIC;
> + }
> +}
> +EXPORT_SYMBOL(generic_fill_statx_atomic_writes);
> +
> /**
> * vfs_getattr_nosec - getattr without security checks
> * @path: file to get attributes from
> @@ -658,6 +689,9 @@ cp_statx(const struct kstat *stat, struct statx __user *buffer)
> tmp.stx_mnt_id = stat->mnt_id;
> tmp.stx_dio_mem_align = stat->dio_mem_align;
> tmp.stx_dio_offset_align = stat->dio_offset_align;
> + tmp.stx_atomic_write_unit_min = stat->atomic_write_unit_min;
> + tmp.stx_atomic_write_unit_max = stat->atomic_write_unit_max;
> + tmp.stx_atomic_write_segments_max = stat->atomic_write_segments_max;
>
> return copy_to_user(buffer, &tmp, sizeof(tmp)) ? -EFAULT : 0;
> }
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index 7271640fd600..531140a7e27a 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -3167,6 +3167,9 @@ extern const struct inode_operations page_symlink_inode_operations;
> extern void kfree_link(void *);
> void generic_fillattr(struct mnt_idmap *, u32, struct inode *, struct kstat *);
> void generic_fill_statx_attr(struct inode *inode, struct kstat *stat);
> +void generic_fill_statx_atomic_writes(struct kstat *stat,
> + unsigned int unit_min,
> + unsigned int unit_max);
We can make 80 col. width even with unit_min in the same first line as of *stat.
> extern int vfs_getattr_nosec(const struct path *, struct kstat *, u32, unsigned int);
> extern int vfs_getattr(const struct path *, struct kstat *, u32, unsigned int);
> void __inode_add_bytes(struct inode *inode, loff_t bytes);
> diff --git a/include/linux/stat.h b/include/linux/stat.h
> index 52150570d37a..2c5e2b8c6559 100644
> --- a/include/linux/stat.h
> +++ b/include/linux/stat.h
> @@ -53,6 +53,9 @@ struct kstat {
> u32 dio_mem_align;
> u32 dio_offset_align;
> u64 change_cookie;
> + u32 atomic_write_unit_min;
> + u32 atomic_write_unit_max;
> + u32 atomic_write_segments_max;
> };
>
> /* These definitions are internal to the kernel for now. Mainly used by nfsd. */
> diff --git a/include/uapi/linux/stat.h b/include/uapi/linux/stat.h
> index 2f2ee82d5517..c0e8e10d1de6 100644
> --- a/include/uapi/linux/stat.h
> +++ b/include/uapi/linux/stat.h
> @@ -127,7 +127,12 @@ struct statx {
> __u32 stx_dio_mem_align; /* Memory buffer alignment for direct I/O */
> __u32 stx_dio_offset_align; /* File offset alignment for direct I/O */
> /* 0xa0 */
> - __u64 __spare3[12]; /* Spare space for future expansion */
> + __u32 stx_atomic_write_unit_min;
> + __u32 stx_atomic_write_unit_max;
> + __u32 stx_atomic_write_segments_max;
Let's add one liner for each of these fields similar to how it was done
for others?
/* Minimum supported atomic write length in bytes */
/* Maximum supported atomic write length in bytes */
/* Maximum no. of segments (iovecs?) supported for atomic write */
> + __u32 __spare1;
> + /* 0xb0 */
> + __u64 __spare3[10]; /* Spare space for future expansion */
> /* 0x100 */
> };
>
> @@ -155,6 +160,7 @@ struct statx {
> #define STATX_MNT_ID 0x00001000U /* Got stx_mnt_id */
> #define STATX_DIOALIGN 0x00002000U /* Want/got direct I/O alignment info */
> #define STATX_MNT_ID_UNIQUE 0x00004000U /* Want/got extended stx_mount_id */
> +#define STATX_WRITE_ATOMIC 0x00008000U /* Want/got atomic_write_* fields */
>
> #define STATX__RESERVED 0x80000000U /* Reserved for future struct statx expansion */
>
> @@ -190,6 +196,7 @@ struct statx {
> #define STATX_ATTR_MOUNT_ROOT 0x00002000 /* Root of a mount */
> #define STATX_ATTR_VERITY 0x00100000 /* [I] Verity protected file */
> #define STATX_ATTR_DAX 0x00200000 /* File is currently in DAX state */
> +#define STATX_ATTR_WRITE_ATOMIC 0x00400000 /* File supports atomic write operations */
>
>
> #endif /* _UAPI_LINUX_STAT_H */
> --
> 2.31.1
On 24/02/2024 18:46, Ritesh Harjani (IBM) wrote:
> John Garry <john.g.garry@oracle.com> writes:
>
>> From: Prasad Singamsetty <prasad.singamsetty@oracle.com>
>>
>> Extend statx system call to return additional info for atomic write support
>> support for a file.
>>
>> Helper function generic_fill_statx_atomic_writes() can be used by FSes to
>> fill in the relevant statx fields.
>>
>> Signed-off-by: Prasad Singamsetty <prasad.singamsetty@oracle.com>
>> #jpg: relocate bdev support to another patch
>
> ^^^ miss maybe?
>> Signed-off-by: John Garry <john.g.garry@oracle.com>
>> ---
>> fs/stat.c | 34 ++++++++++++++++++++++++++++++++++
>> include/linux/fs.h | 3 +++
>> include/linux/stat.h | 3 +++
>> include/uapi/linux/stat.h | 9 ++++++++-
>> 4 files changed, 48 insertions(+), 1 deletion(-)
>>
>> diff --git a/fs/stat.c b/fs/stat.c
>> index 77cdc69eb422..522787a4ab6a 100644
>> --- a/fs/stat.c
>> +++ b/fs/stat.c
>> @@ -89,6 +89,37 @@ void generic_fill_statx_attr(struct inode *inode, struct kstat *stat)
>> }
>> EXPORT_SYMBOL(generic_fill_statx_attr);
>>
>> +/**
>> + * generic_fill_statx_atomic_writes - Fill in the atomic writes statx attributes
>> + * @stat: Where to fill in the attribute flags
>> + * @unit_min: Minimum supported atomic write length
> + * @unit_min: Minimum supported atomic write length in bytes
>
>
>> + * @unit_max: Maximum supported atomic write length
> + * @unit_max: Maximum supported atomic write length in bytes
>
> mentioning unit of the length might be useful here.
Yeah, I have already improved this as suggested.
>
>> + *
>> + * Fill in the STATX{_ATTR}_WRITE_ATOMIC flags in the kstat structure from
>> + * atomic write unit_min and unit_max values.
>> + */
>> +void generic_fill_statx_atomic_writes(struct kstat *stat,
>> + unsigned int unit_min,
>
> This (unit_min) can still go above in the same line.
ok
>
>> + unsigned int unit_max)
>> +{
>> + /* Confirm that the request type is known */
>> + stat->result_mask |= STATX_WRITE_ATOMIC;
>> +
>> + /* Confirm that the file attribute type is known */
>> + stat->attributes_mask |= STATX_ATTR_WRITE_ATOMIC;
>> +
>> + if (unit_min) {
>> + stat->atomic_write_unit_min = unit_min;
>> + stat->atomic_write_unit_max = unit_max;
>> + /* Initially only allow 1x segment */
>> + stat->atomic_write_segments_max = 1;
>
> Please log info about this in commit message about where this limit came
> from?
ok
> Is it since we only support ubuf (which IIUC, only supports 1
> segment)? Later when we will add support for iovec, this limit can be
> lifted?
It's not that we only support ubuf, but rather we only support one
segment and that gives a ubuf type iter.
This is all related to how can can guarantee a unit_max advertised to
userspace can always be written atomically.
This is further mentioned in the block layer patch.
>
>> +
>> + /* Confirm atomic writes are actually supported */
>> + stat->attributes |= STATX_ATTR_WRITE_ATOMIC;
>> + }
>> +}
>> +EXPORT_SYMBOL(generic_fill_statx_atomic_writes);
>> +
>> /**
>> * vfs_getattr_nosec - getattr without security checks
>> * @path: file to get attributes from
>> @@ -658,6 +689,9 @@ cp_statx(const struct kstat *stat, struct statx __user *buffer)
>> tmp.stx_mnt_id = stat->mnt_id;
>> tmp.stx_dio_mem_align = stat->dio_mem_align;
>> tmp.stx_dio_offset_align = stat->dio_offset_align;
>> + tmp.stx_atomic_write_unit_min = stat->atomic_write_unit_min;
>> + tmp.stx_atomic_write_unit_max = stat->atomic_write_unit_max;
>> + tmp.stx_atomic_write_segments_max = stat->atomic_write_segments_max;
>>
>> return copy_to_user(buffer, &tmp, sizeof(tmp)) ? -EFAULT : 0;
>> }
>> diff --git a/include/linux/fs.h b/include/linux/fs.h
>> index 7271640fd600..531140a7e27a 100644
>> --- a/include/linux/fs.h
>> +++ b/include/linux/fs.h
>> @@ -3167,6 +3167,9 @@ extern const struct inode_operations page_symlink_inode_operations;
>> extern void kfree_link(void *);
>> void generic_fillattr(struct mnt_idmap *, u32, struct inode *, struct kstat *);
>> void generic_fill_statx_attr(struct inode *inode, struct kstat *stat);
>> +void generic_fill_statx_atomic_writes(struct kstat *stat,
>> + unsigned int unit_min,
>> + unsigned int unit_max);
>
> We can make 80 col. width even with unit_min in the same first line as of *stat.
ok, I can check this.
>
>
>> extern int vfs_getattr_nosec(const struct path *, struct kstat *, u32, unsigned int);
>> extern int vfs_getattr(const struct path *, struct kstat *, u32, unsigned int);
>> void __inode_add_bytes(struct inode *inode, loff_t bytes);
>> diff --git a/include/linux/stat.h b/include/linux/stat.h
>> index 52150570d37a..2c5e2b8c6559 100644
>> --- a/include/linux/stat.h
>> +++ b/include/linux/stat.h
>> @@ -53,6 +53,9 @@ struct kstat {
>> u32 dio_mem_align;
>> u32 dio_offset_align;
>> u64 change_cookie;
>> + u32 atomic_write_unit_min;
>> + u32 atomic_write_unit_max;
>> + u32 atomic_write_segments_max;
>> };
>>
>> /* These definitions are internal to the kernel for now. Mainly used by nfsd. */
>> diff --git a/include/uapi/linux/stat.h b/include/uapi/linux/stat.h
>> index 2f2ee82d5517..c0e8e10d1de6 100644
>> --- a/include/uapi/linux/stat.h
>> +++ b/include/uapi/linux/stat.h
>> @@ -127,7 +127,12 @@ struct statx {
>> __u32 stx_dio_mem_align; /* Memory buffer alignment for direct I/O */
>> __u32 stx_dio_offset_align; /* File offset alignment for direct I/O */
>> /* 0xa0 */
>> - __u64 __spare3[12]; /* Spare space for future expansion */
>> + __u32 stx_atomic_write_unit_min;
>> + __u32 stx_atomic_write_unit_max;
>> + __u32 stx_atomic_write_segments_max;
>
> Let's add one liner for each of these fields similar to how it was done
> for others?
>
> /* Minimum supported atomic write length in bytes */
> /* Maximum supported atomic write length in bytes */
> /* Maximum no. of segments (iovecs?) supported for atomic write */
ok
>
>
>> + __u32 __spare1;
>> + /* 0xb0 */
>> + __u64 __spare3[10]; /* Spare space for future expansion */
>> /* 0x100 */
>> };
>>
>> @@ -155,6 +160,7 @@ struct statx {
>> #define STATX_MNT_ID 0x00001000U /* Got stx_mnt_id */
>> #define STATX_DIOALIGN 0x00002000U /* Want/got direct I/O alignment info */
>> #define STATX_MNT_ID_UNIQUE 0x00004000U /* Want/got extended stx_mount_id */
>> +#define STATX_WRITE_ATOMIC 0x00008000U /* Want/got atomic_write_* fields */
>>
>> #define STATX__RESERVED 0x80000000U /* Reserved for future struct statx expansion */
>>
>> @@ -190,6 +196,7 @@ struct statx {
>> #define STATX_ATTR_MOUNT_ROOT 0x00002000 /* Root of a mount */
>> #define STATX_ATTR_VERITY 0x00100000 /* [I] Verity protected file */
>> #define STATX_ATTR_DAX 0x00200000 /* File is currently in DAX state */
>> +#define STATX_ATTR_WRITE_ATOMIC 0x00400000 /* File supports atomic write operations */
>>
>>
>> #endif /* _UAPI_LINUX_STAT_H */
>> --
>> 2.31.1
Thanks,
John
> +EXPORT_SYMBOL(generic_fill_statx_atomic_writes); EXPORT_SYMBOL_GPL for any new feature, please.
On 20/02/2024 08:20, Christoph Hellwig wrote: >> +EXPORT_SYMBOL(generic_fill_statx_atomic_writes); > EXPORT_SYMBOL_GPL for any new feature, please. ok, thanks.
On Mon, Feb 19, 2024 at 01:01:02PM +0000, John Garry wrote:
> From: Prasad Singamsetty <prasad.singamsetty@oracle.com>
>
> Extend statx system call to return additional info for atomic write support
> support for a file.
>
> Helper function generic_fill_statx_atomic_writes() can be used by FSes to
> fill in the relevant statx fields.
>
> Signed-off-by: Prasad Singamsetty <prasad.singamsetty@oracle.com>
> #jpg: relocate bdev support to another patch
> Signed-off-by: John Garry <john.g.garry@oracle.com>
> ---
> fs/stat.c | 34 ++++++++++++++++++++++++++++++++++
> include/linux/fs.h | 3 +++
> include/linux/stat.h | 3 +++
> include/uapi/linux/stat.h | 9 ++++++++-
> 4 files changed, 48 insertions(+), 1 deletion(-)
>
> diff --git a/fs/stat.c b/fs/stat.c
> index 77cdc69eb422..522787a4ab6a 100644
> --- a/fs/stat.c
> +++ b/fs/stat.c
> @@ -89,6 +89,37 @@ void generic_fill_statx_attr(struct inode *inode, struct kstat *stat)
> }
> EXPORT_SYMBOL(generic_fill_statx_attr);
>
> +/**
> + * generic_fill_statx_atomic_writes - Fill in the atomic writes statx attributes
> + * @stat: Where to fill in the attribute flags
> + * @unit_min: Minimum supported atomic write length
> + * @unit_max: Maximum supported atomic write length
> + *
> + * Fill in the STATX{_ATTR}_WRITE_ATOMIC flags in the kstat structure from
> + * atomic write unit_min and unit_max values.
> + */
> +void generic_fill_statx_atomic_writes(struct kstat *stat,
> + unsigned int unit_min,
> + unsigned int unit_max)
> +{
> + /* Confirm that the request type is known */
> + stat->result_mask |= STATX_WRITE_ATOMIC;
> +
> + /* Confirm that the file attribute type is known */
> + stat->attributes_mask |= STATX_ATTR_WRITE_ATOMIC;
> +
> + if (unit_min) {
> + stat->atomic_write_unit_min = unit_min;
> + stat->atomic_write_unit_max = unit_max;
> + /* Initially only allow 1x segment */
> + stat->atomic_write_segments_max = 1;
> +
> + /* Confirm atomic writes are actually supported */
> + stat->attributes |= STATX_ATTR_WRITE_ATOMIC;
> + }
> +}
> +EXPORT_SYMBOL(generic_fill_statx_atomic_writes);
What units are these in? Nothing in the patch or commit description
tells us....
-Dave.
--
Dave Chinner
david@fromorbit.com
On 19/02/2024 22:28, Dave Chinner wrote:
>>
>> +/**
>> + * generic_fill_statx_atomic_writes - Fill in the atomic writes statx attributes
>> + * @stat: Where to fill in the attribute flags
>> + * @unit_min: Minimum supported atomic write length
>> + * @unit_max: Maximum supported atomic write length
>> + *
>> + * Fill in the STATX{_ATTR}_WRITE_ATOMIC flags in the kstat structure from
>> + * atomic write unit_min and unit_max values.
>> + */
>> +void generic_fill_statx_atomic_writes(struct kstat *stat,
>> + unsigned int unit_min,
>> + unsigned int unit_max)
>> +{
>> + /* Confirm that the request type is known */
>> + stat->result_mask |= STATX_WRITE_ATOMIC;
>> +
>> + /* Confirm that the file attribute type is known */
>> + stat->attributes_mask |= STATX_ATTR_WRITE_ATOMIC;
>> +
>> + if (unit_min) {
>> + stat->atomic_write_unit_min = unit_min;
>> + stat->atomic_write_unit_max = unit_max;
>> + /* Initially only allow 1x segment */
>> + stat->atomic_write_segments_max = 1;
>> +
>> + /* Confirm atomic writes are actually supported */
>> + stat->attributes |= STATX_ATTR_WRITE_ATOMIC;
>> + }
>> +}
>> +EXPORT_SYMBOL(generic_fill_statx_atomic_writes);
> What units are these in? Nothing in the patch or commit description
> tells us....
I can append the current comments to mention that the unit is bytes.
Thanks,
John
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