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Message-Id: <20250506090427.2549456-17-john.g.garry@oracle.com> Date: Tue, 6 May 2025 09:04:26 +0000 From: John Garry <john.g.garry@...cle.com> To: brauner@...nel.org, djwong@...nel.org, hch@....de, viro@...iv.linux.org.uk, jack@...e.cz, cem@...nel.org Cc: linux-fsdevel@...r.kernel.org, dchinner@...hat.com, linux-xfs@...r.kernel.org, linux-kernel@...r.kernel.org, ojaswin@...ux.ibm.com, ritesh.list@...il.com, martin.petersen@...cle.com, linux-ext4@...r.kernel.org, linux-block@...r.kernel.org, catherine.hoang@...cle.com, linux-api@...r.kernel.org, John Garry <john.g.garry@...cle.com> Subject: [PATCH v12 16/17] xfs: update atomic write limits Update the limits returned from xfs_get_atomic_write_{min, max, max_opt)(). No reflink support always means no CoW-based atomic writes. For updating xfs_get_atomic_write_min(), we support blocksize only and that depends on HW or reflink support. For updating xfs_get_atomic_write_max(), for no reflink, we are limited to blocksize but only if HW support. Otherwise we are limited to combined limit in mp->m_atomic_write_unit_max. For updating xfs_get_atomic_write_max_opt(), ultimately we are limited by the bdev atomic write limit. If xfs_get_atomic_write_max() does not report > 1x blocksize, then just continue to report 0 as before. Reviewed-by: Darrick J. Wong <djwong@...nel.org> [djwong: update comments in the helper functions] Signed-off-by: Darrick J. Wong <djwong@...nel.org> Reviewed-by: Christoph Hellwig <hch@....de> Signed-off-by: John Garry <john.g.garry@...cle.com> --- fs/xfs/xfs_file.c | 2 +- fs/xfs/xfs_iops.c | 52 +++++++++++++++++++++++++++++++++++++++++------ 2 files changed, 47 insertions(+), 7 deletions(-) diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c index f4a66ff85748..48254a72071b 100644 --- a/fs/xfs/xfs_file.c +++ b/fs/xfs/xfs_file.c @@ -1557,7 +1557,7 @@ xfs_file_open( if (xfs_is_shutdown(XFS_M(inode->i_sb))) return -EIO; file->f_mode |= FMODE_NOWAIT | FMODE_CAN_ODIRECT; - if (xfs_inode_can_hw_atomic_write(XFS_I(inode))) + if (xfs_get_atomic_write_min(XFS_I(inode)) > 0) file->f_mode |= FMODE_CAN_ATOMIC_WRITE; return generic_file_open(inode, file); } diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c index 77a0606e9dc9..8cddbb7c149b 100644 --- a/fs/xfs/xfs_iops.c +++ b/fs/xfs/xfs_iops.c @@ -605,27 +605,67 @@ unsigned int xfs_get_atomic_write_min( struct xfs_inode *ip) { - if (!xfs_inode_can_hw_atomic_write(ip)) - return 0; + struct xfs_mount *mp = ip->i_mount; + + /* + * If we can complete an atomic write via atomic out of place writes, + * then advertise a minimum size of one fsblock. Without this + * mechanism, we can only guarantee atomic writes up to a single LBA. + * + * If out of place writes are not available, we can guarantee an atomic + * write of exactly one single fsblock if the bdev will make that + * guarantee for us. + */ + if (xfs_inode_can_hw_atomic_write(ip) || xfs_can_sw_atomic_write(mp)) + return mp->m_sb.sb_blocksize; - return ip->i_mount->m_sb.sb_blocksize; + return 0; } unsigned int xfs_get_atomic_write_max( struct xfs_inode *ip) { - if (!xfs_inode_can_hw_atomic_write(ip)) + struct xfs_mount *mp = ip->i_mount; + + /* + * If out of place writes are not available, we can guarantee an atomic + * write of exactly one single fsblock if the bdev will make that + * guarantee for us. + */ + if (!xfs_can_sw_atomic_write(mp)) { + if (xfs_inode_can_hw_atomic_write(ip)) + return mp->m_sb.sb_blocksize; return 0; + } - return ip->i_mount->m_sb.sb_blocksize; + /* + * If we can complete an atomic write via atomic out of place writes, + * then advertise a maximum size of whatever we can complete through + * that means. Hardware support is reported via max_opt, not here. + */ + if (XFS_IS_REALTIME_INODE(ip)) + return XFS_FSB_TO_B(mp, mp->m_groups[XG_TYPE_RTG].awu_max); + return XFS_FSB_TO_B(mp, mp->m_groups[XG_TYPE_AG].awu_max); } unsigned int xfs_get_atomic_write_max_opt( struct xfs_inode *ip) { - return 0; + unsigned int awu_max = xfs_get_atomic_write_max(ip); + + /* if the max is 1x block, then just keep behaviour that opt is 0 */ + if (awu_max <= ip->i_mount->m_sb.sb_blocksize) + return 0; + + /* + * Advertise the maximum size of an atomic write that we can tell the + * block device to perform for us. In general the bdev limit will be + * less than our out of place write limit, but we don't want to exceed + * the awu_max. + */ + return min(awu_max, xfs_inode_buftarg(ip)->bt_bdev_awu_max); } static void -- 2.31.1
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