On Mon, Jun 10, 2024 at 10:43:23AM +0000, John Garry wrote: > From: Prasad Singamsetty <[email protected]> > > 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. For now atomic_write_segments_max will > always be 1, otherwise some rules would need to be imposed on iovec length > and alignment, which we don't want now. > > Signed-off-by: Prasad Singamsetty <[email protected]> > jpg: relocate bdev support to another patch > Signed-off-by: John Garry <[email protected]>
Looks fine to me, assuming there's a manpage update lurking somewhere? Reviewed-by: Darrick J. Wong <[email protected]> --D > --- > fs/stat.c | 34 ++++++++++++++++++++++++++++++++++ > include/linux/fs.h | 3 +++ > include/linux/stat.h | 3 +++ > include/uapi/linux/stat.h | 12 ++++++++++-- > 4 files changed, 50 insertions(+), 2 deletions(-) > > diff --git a/fs/stat.c b/fs/stat.c > index 70bd3e888cfa..72d0e6357b91 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 atomic writes statx attributes > + * @stat: Where to fill in the attribute flags > + * @unit_min: Minimum supported atomic write length in bytes > + * @unit_max: Maximum supported atomic write length in bytes > + * > + * 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_GPL(generic_fill_statx_atomic_writes); > + > /** > * vfs_getattr_nosec - getattr without security checks > * @path: file to get attributes from > @@ -659,6 +690,9 @@ cp_statx(const struct kstat *stat, struct statx __user > *buffer) > tmp.stx_dio_mem_align = stat->dio_mem_align; > tmp.stx_dio_offset_align = stat->dio_offset_align; > tmp.stx_subvol = stat->subvol; > + 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 e049414bef7d..db26b4a70c62 100644 > --- a/include/linux/fs.h > +++ b/include/linux/fs.h > @@ -3235,6 +3235,9 @@ 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 bf92441dbad2..3d900c86981c 100644 > --- a/include/linux/stat.h > +++ b/include/linux/stat.h > @@ -54,6 +54,9 @@ struct kstat { > u32 dio_offset_align; > u64 change_cookie; > u64 subvol; > + 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 67626d535316..887a25286441 100644 > --- a/include/uapi/linux/stat.h > +++ b/include/uapi/linux/stat.h > @@ -126,9 +126,15 @@ struct statx { > __u64 stx_mnt_id; > __u32 stx_dio_mem_align; /* Memory buffer alignment for direct > I/O */ > __u32 stx_dio_offset_align; /* File offset alignment for direct I/O > */ > - __u64 stx_subvol; /* Subvolume identifier */ > /* 0xa0 */ > - __u64 __spare3[11]; /* Spare space for future expansion */ > + __u64 stx_subvol; /* Subvolume identifier */ > + __u32 stx_atomic_write_unit_min; /* Min atomic write unit in > bytes */ > + __u32 stx_atomic_write_unit_max; /* Max atomic write unit in > bytes */ > + /* 0xb0 */ > + __u32 stx_atomic_write_segments_max; /* Max atomic write segment > count */ > + __u32 __spare1[1]; > + /* 0xb8 */ > + __u64 __spare3[9]; /* Spare space for future expansion */ > /* 0x100 */ > }; > > @@ -157,6 +163,7 @@ struct statx { > #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_SUBVOL 0x00008000U /* Want/got stx_subvol */ > +#define STATX_WRITE_ATOMIC 0x00010000U /* Want/got atomic_write_* > fields */ > > #define STATX__RESERVED 0x80000000U /* Reserved for future > struct statx expansion */ > > @@ -192,6 +199,7 @@ 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 > >
