On Mon, Sep 30, 2024 at 12:54:36PM +0000, John Garry wrote: > Support providing info on atomic write unit min and max for an inode. > > For simplicity, currently we limit the min at the FS block size. As for > max, we limit also at FS block size, as there is no current method to > guarantee extent alignment or granularity for regular files. > > Signed-off-by: John Garry <john.g.garry@xxxxxxxxxx> > --- > fs/xfs/xfs_inode.h | 17 +++++++++++++++++ > fs/xfs/xfs_iops.c | 24 ++++++++++++++++++++++++ > 2 files changed, 41 insertions(+) > > diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h > index 1c62ee294a5a..1ea73402d592 100644 > --- a/fs/xfs/xfs_inode.h > +++ b/fs/xfs/xfs_inode.h > @@ -332,6 +332,23 @@ static inline bool xfs_inode_has_atomicwrites(struct xfs_inode *ip) > return ip->i_diflags2 & XFS_DIFLAG2_ATOMICWRITES; > } > > +static inline bool > +xfs_inode_can_atomicwrite( > + struct xfs_inode *ip) > +{ > + struct xfs_mount *mp = ip->i_mount; > + struct xfs_buftarg *target = xfs_inode_buftarg(ip); > + > + if (!xfs_inode_has_atomicwrites(ip)) > + return false; > + if (mp->m_sb.sb_blocksize < target->bt_bdev_awu_min) > + return false; > + if (mp->m_sb.sb_blocksize > target->bt_bdev_awu_max) > + return false; > + > + return true; > +} > + > /* > * In-core inode flags. > */ > diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c > index ee79cf161312..915d057db9bb 100644 > --- a/fs/xfs/xfs_iops.c > +++ b/fs/xfs/xfs_iops.c > @@ -570,6 +570,23 @@ xfs_stat_blksize( > return max_t(uint32_t, PAGE_SIZE, mp->m_sb.sb_blocksize); > } > > +static void > +xfs_get_atomic_write_attr( > + struct xfs_inode *ip, > + unsigned int *unit_min, > + unsigned int *unit_max) > +{ > + struct xfs_mount *mp = ip->i_mount; > + struct xfs_sb *sbp = &mp->m_sb; > + > + if (!xfs_inode_can_atomicwrite(ip)) { > + *unit_min = *unit_max = 0; > + return; > + } > + > + *unit_min = *unit_max = sbp->sb_blocksize; Ok, so we're only supporting untorn writes if they're exactly the fs blocksize, and 1 fsblock is between awu_min/max. That simplifies a lot of things. :) Not supporting sub-fsblock atomic writes means that we'll never hit the directio COW fallback code, which uses the pagecache. Not supporting multi-fsblock atomic writes means that you don't have to figure out how to ensure that we always do cow on forcealign granularity. Though as I pointed out elsewhere in this thread, that's a forcealign problem. Yay! ;) > +} > + > STATIC int > xfs_vn_getattr( > struct mnt_idmap *idmap, > @@ -643,6 +660,13 @@ xfs_vn_getattr( > stat->dio_mem_align = bdev_dma_alignment(bdev) + 1; > stat->dio_offset_align = bdev_logical_block_size(bdev); > } > + if (request_mask & STATX_WRITE_ATOMIC) { > + unsigned int unit_min, unit_max; > + > + xfs_get_atomic_write_attr(ip, &unit_min, &unit_max); > + generic_fill_statx_atomic_writes(stat, > + unit_min, unit_max); Consistent indenting and wrapping, please: xfs_get_atomic_write_attr(ip, &unit_min, &unit_max); generic_fill_statx_atomic_writes(stat, unit_min, unit_max); With that fixed, Reviewed-by: Darrick J. Wong <djwong@xxxxxxxxxx> --D > + } > fallthrough; > default: > stat->blksize = xfs_stat_blksize(ip); > -- > 2.31.1 > >