| Message ID | 20250408104209.1852036-2-john.g.garry@oracle.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | large atomic writes for xfs | expand |
This probably should have cc'd linux-api... On Tue, Apr 08, 2025 at 10:41:58AM +0000, John Garry wrote: > XFS will be able to support large atomic writes (atomic write > 1x block) > in future. This will be achieved by using different operating methods, > depending on the size of the write. > > Specifically a new method of operation based in FS atomic extent remapping > will be supported in addition to the current HW offload-based method. > > The FS method will generally be appreciably slower performing than the > HW-offload method. However the FS method will be typically able to > contribute to achieving a larger atomic write unit max limit. > > XFS will support a hybrid mode, where HW offload method will be used when > possible, i.e. HW offload is used when the length of the write is > supported, and for other times FS-based atomic writes will be used. > > As such, there is an atomic write length at which the user may experience > appreciably slower performance. > > Advertise this limit in a new statx field, stx_atomic_write_unit_max_opt. > > When zero, it means that there is no such performance boundary. > > Masks STATX{_ATTR}_WRITE_ATOMIC can be used to get this new field. This is > ok for older kernels which don't support this new field, as they would > report 0 in this field (from zeroing in cp_statx()) already. Furthermore > those older kernels don't support large atomic writes - apart from block > fops, but there would be consistent performance there for atomic writes > in range [unit min, unit max]. > > Signed-off-by: John Garry <john.g.garry@oracle.com> Seems fine to me, but I imagine others have stronger opinions. Acked-by: "Darrick J. Wong" <djwong@kernel.org> --D > --- > block/bdev.c | 3 ++- > fs/ext4/inode.c | 2 +- > fs/stat.c | 6 +++++- > fs/xfs/xfs_iops.c | 2 +- > include/linux/fs.h | 3 ++- > include/linux/stat.h | 1 + > include/uapi/linux/stat.h | 8 ++++++-- > 7 files changed, 18 insertions(+), 7 deletions(-) > > diff --git a/block/bdev.c b/block/bdev.c > index 4844d1e27b6f..b4afc1763e8e 100644 > --- a/block/bdev.c > +++ b/block/bdev.c > @@ -1301,7 +1301,8 @@ void bdev_statx(struct path *path, struct kstat *stat, > > generic_fill_statx_atomic_writes(stat, > queue_atomic_write_unit_min_bytes(bd_queue), > - queue_atomic_write_unit_max_bytes(bd_queue)); > + queue_atomic_write_unit_max_bytes(bd_queue), > + 0); > } > > stat->blksize = bdev_io_min(bdev); > diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c > index 1dc09ed5d403..51a45699112c 100644 > --- a/fs/ext4/inode.c > +++ b/fs/ext4/inode.c > @@ -5663,7 +5663,7 @@ int ext4_getattr(struct mnt_idmap *idmap, const struct path *path, > awu_max = sbi->s_awu_max; > } > > - generic_fill_statx_atomic_writes(stat, awu_min, awu_max); > + generic_fill_statx_atomic_writes(stat, awu_min, awu_max, 0); > } > > flags = ei->i_flags & EXT4_FL_USER_VISIBLE; > diff --git a/fs/stat.c b/fs/stat.c > index f13308bfdc98..c41855f62d22 100644 > --- a/fs/stat.c > +++ b/fs/stat.c > @@ -136,13 +136,15 @@ EXPORT_SYMBOL(generic_fill_statx_attr); > * @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 > + * @unit_max_opt: Optimised 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) > + unsigned int unit_max, > + unsigned int unit_max_opt) > { > /* Confirm that the request type is known */ > stat->result_mask |= STATX_WRITE_ATOMIC; > @@ -153,6 +155,7 @@ void generic_fill_statx_atomic_writes(struct kstat *stat, > if (unit_min) { > stat->atomic_write_unit_min = unit_min; > stat->atomic_write_unit_max = unit_max; > + stat->atomic_write_unit_max_opt = unit_max_opt; > /* Initially only allow 1x segment */ > stat->atomic_write_segments_max = 1; > > @@ -732,6 +735,7 @@ cp_statx(const struct kstat *stat, struct statx __user *buffer) > 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; > + tmp.stx_atomic_write_unit_max_opt = stat->atomic_write_unit_max_opt; > > return copy_to_user(buffer, &tmp, sizeof(tmp)) ? -EFAULT : 0; > } > diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c > index 756bd3ca8e00..f0e5d83195df 100644 > --- a/fs/xfs/xfs_iops.c > +++ b/fs/xfs/xfs_iops.c > @@ -610,7 +610,7 @@ xfs_report_atomic_write( > > if (xfs_inode_can_atomicwrite(ip)) > unit_min = unit_max = ip->i_mount->m_sb.sb_blocksize; > - generic_fill_statx_atomic_writes(stat, unit_min, unit_max); > + generic_fill_statx_atomic_writes(stat, unit_min, unit_max, 0); > } > > STATIC int > diff --git a/include/linux/fs.h b/include/linux/fs.h > index 016b0fe1536e..7b19d8f99aff 100644 > --- a/include/linux/fs.h > +++ b/include/linux/fs.h > @@ -3475,7 +3475,8 @@ 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); > + unsigned int unit_max, > + unsigned int unit_max_opt); > 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 be7496a6a0dd..e3d00e7bb26d 100644 > --- a/include/linux/stat.h > +++ b/include/linux/stat.h > @@ -57,6 +57,7 @@ struct kstat { > u32 dio_read_offset_align; > u32 atomic_write_unit_min; > u32 atomic_write_unit_max; > + u32 atomic_write_unit_max_opt; > u32 atomic_write_segments_max; > }; > > diff --git a/include/uapi/linux/stat.h b/include/uapi/linux/stat.h > index f78ee3670dd5..1686861aae20 100644 > --- a/include/uapi/linux/stat.h > +++ b/include/uapi/linux/stat.h > @@ -182,8 +182,12 @@ struct statx { > /* File offset alignment for direct I/O reads */ > __u32 stx_dio_read_offset_align; > > - /* 0xb8 */ > - __u64 __spare3[9]; /* Spare space for future expansion */ > + /* Optimised max atomic write unit in bytes */ > + __u32 stx_atomic_write_unit_max_opt; > + __u32 __spare2[1]; > + > + /* 0xc0 */ > + __u64 __spare3[8]; /* Spare space for future expansion */ > > /* 0x100 */ > }; > -- > 2.31.1 > >
Looks good:
Reviewed-by: Christoph Hellwig <hch@lst.de>
diff --git a/block/bdev.c b/block/bdev.c index 4844d1e27b6f..b4afc1763e8e 100644 --- a/block/bdev.c +++ b/block/bdev.c @@ -1301,7 +1301,8 @@ void bdev_statx(struct path *path, struct kstat *stat, generic_fill_statx_atomic_writes(stat, queue_atomic_write_unit_min_bytes(bd_queue), - queue_atomic_write_unit_max_bytes(bd_queue)); + queue_atomic_write_unit_max_bytes(bd_queue), + 0); } stat->blksize = bdev_io_min(bdev); diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 1dc09ed5d403..51a45699112c 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -5663,7 +5663,7 @@ int ext4_getattr(struct mnt_idmap *idmap, const struct path *path, awu_max = sbi->s_awu_max; } - generic_fill_statx_atomic_writes(stat, awu_min, awu_max); + generic_fill_statx_atomic_writes(stat, awu_min, awu_max, 0); } flags = ei->i_flags & EXT4_FL_USER_VISIBLE; diff --git a/fs/stat.c b/fs/stat.c index f13308bfdc98..c41855f62d22 100644 --- a/fs/stat.c +++ b/fs/stat.c @@ -136,13 +136,15 @@ EXPORT_SYMBOL(generic_fill_statx_attr); * @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 + * @unit_max_opt: Optimised 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) + unsigned int unit_max, + unsigned int unit_max_opt) { /* Confirm that the request type is known */ stat->result_mask |= STATX_WRITE_ATOMIC; @@ -153,6 +155,7 @@ void generic_fill_statx_atomic_writes(struct kstat *stat, if (unit_min) { stat->atomic_write_unit_min = unit_min; stat->atomic_write_unit_max = unit_max; + stat->atomic_write_unit_max_opt = unit_max_opt; /* Initially only allow 1x segment */ stat->atomic_write_segments_max = 1; @@ -732,6 +735,7 @@ cp_statx(const struct kstat *stat, struct statx __user *buffer) 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; + tmp.stx_atomic_write_unit_max_opt = stat->atomic_write_unit_max_opt; return copy_to_user(buffer, &tmp, sizeof(tmp)) ? -EFAULT : 0; } diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c index 756bd3ca8e00..f0e5d83195df 100644 --- a/fs/xfs/xfs_iops.c +++ b/fs/xfs/xfs_iops.c @@ -610,7 +610,7 @@ xfs_report_atomic_write( if (xfs_inode_can_atomicwrite(ip)) unit_min = unit_max = ip->i_mount->m_sb.sb_blocksize; - generic_fill_statx_atomic_writes(stat, unit_min, unit_max); + generic_fill_statx_atomic_writes(stat, unit_min, unit_max, 0); } STATIC int diff --git a/include/linux/fs.h b/include/linux/fs.h index 016b0fe1536e..7b19d8f99aff 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -3475,7 +3475,8 @@ 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); + unsigned int unit_max, + unsigned int unit_max_opt); 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 be7496a6a0dd..e3d00e7bb26d 100644 --- a/include/linux/stat.h +++ b/include/linux/stat.h @@ -57,6 +57,7 @@ struct kstat { u32 dio_read_offset_align; u32 atomic_write_unit_min; u32 atomic_write_unit_max; + u32 atomic_write_unit_max_opt; u32 atomic_write_segments_max; }; diff --git a/include/uapi/linux/stat.h b/include/uapi/linux/stat.h index f78ee3670dd5..1686861aae20 100644 --- a/include/uapi/linux/stat.h +++ b/include/uapi/linux/stat.h @@ -182,8 +182,12 @@ struct statx { /* File offset alignment for direct I/O reads */ __u32 stx_dio_read_offset_align; - /* 0xb8 */ - __u64 __spare3[9]; /* Spare space for future expansion */ + /* Optimised max atomic write unit in bytes */ + __u32 stx_atomic_write_unit_max_opt; + __u32 __spare2[1]; + + /* 0xc0 */ + __u64 __spare3[8]; /* Spare space for future expansion */ /* 0x100 */ };
XFS will be able to support large atomic writes (atomic write > 1x block) in future. This will be achieved by using different operating methods, depending on the size of the write. Specifically a new method of operation based in FS atomic extent remapping will be supported in addition to the current HW offload-based method. The FS method will generally be appreciably slower performing than the HW-offload method. However the FS method will be typically able to contribute to achieving a larger atomic write unit max limit. XFS will support a hybrid mode, where HW offload method will be used when possible, i.e. HW offload is used when the length of the write is supported, and for other times FS-based atomic writes will be used. As such, there is an atomic write length at which the user may experience appreciably slower performance. Advertise this limit in a new statx field, stx_atomic_write_unit_max_opt. When zero, it means that there is no such performance boundary. Masks STATX{_ATTR}_WRITE_ATOMIC can be used to get this new field. This is ok for older kernels which don't support this new field, as they would report 0 in this field (from zeroing in cp_statx()) already. Furthermore those older kernels don't support large atomic writes - apart from block fops, but there would be consistent performance there for atomic writes in range [unit min, unit max]. Signed-off-by: John Garry <john.g.garry@oracle.com> --- block/bdev.c | 3 ++- fs/ext4/inode.c | 2 +- fs/stat.c | 6 +++++- fs/xfs/xfs_iops.c | 2 +- include/linux/fs.h | 3 ++- include/linux/stat.h | 1 + include/uapi/linux/stat.h | 8 ++++++-- 7 files changed, 18 insertions(+), 7 deletions(-)