On Tue, Apr 21, 2020 at 12:17:52PM -0700, ira.weiny@xxxxxxxxx wrote:
> From: Ira Weiny <ira.weiny@xxxxxxxxx>
>
> Because of the separation of FS_XFLAG_DAX from S_DAX and the delayed
> setting of S_DAX, data invalidation no longer needs to happen when
> FS_XFLAG_DAX is changed.
>
> Change xfs_ioctl_setattr_dax_invalidate() to be
> xfs_ioctl_dax_check_set_cache() and alter the code to reflect the new
> functionality.
>
> Furthermore, we no longer need the locking so we remove the join_flags
> logic.
>
> Signed-off-by: Ira Weiny <ira.weiny@xxxxxxxxx>
>
> ---
> Changes from V8:
> Change name of function to xfs_ioctl_dax_check_set_cache()
> Update commit message
> Fix bit manipulations
>
> Changes from V7:
> Use new flag_inode_dontcache()
> Skip don't cache if mount over ride is active.
>
> Changes from v6:
> Fix completely broken implementation and update commit message.
> Use the new VFS layer I_DONTCACHE to facilitate inode eviction
> and S_DAX changing on drop_caches
>
> Changes from v5:
> New patch
> ---
> fs/xfs/xfs_ioctl.c | 108 +++++++++------------------------------------
> 1 file changed, 20 insertions(+), 88 deletions(-)
>
> diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
> index 104495ac187c..b87b571a6748 100644
> --- a/fs/xfs/xfs_ioctl.c
> +++ b/fs/xfs/xfs_ioctl.c
> @@ -1245,64 +1245,26 @@ xfs_ioctl_setattr_xflags(
> return 0;
> }
>
> -/*
> - * If we are changing DAX flags, we have to ensure the file is clean and any
> - * cached objects in the address space are invalidated and removed. This
> - * requires us to lock out other IO and page faults similar to a truncate
> - * operation. The locks need to be held until the transaction has been committed
> - * so that the cache invalidation is atomic with respect to the DAX flag
> - * manipulation.
> - */
> -static int
> -xfs_ioctl_setattr_dax_invalidate(
> +static void
> +xfs_ioctl_dax_check_set_cache(
That's a ... strange name. Set cache on what?
Oh, this is the function that sets I_DONTCACHE if an FS_XFLAG_DAX change
could have an immediate effect on S_DAX (assuming no other users). What
do you think of the following?
/*
* If a change to FS_XFLAG_DAX will result in an change to S_DAX
* the next time the incore inode is initialized, set the VFS
* I_DONTCACHE flag to try to hurry that along.
*/
static void
xfs_ioctl_try_change_vfs_dax(...)
--D
> struct xfs_inode *ip,
> - struct fsxattr *fa,
> - int *join_flags)
> + struct fsxattr *fa)
> {
> - struct inode *inode = VFS_I(ip);
> - struct super_block *sb = inode->i_sb;
> - int error;
> -
> - *join_flags = 0;
> -
> - /*
> - * It is only valid to set the DAX flag on regular files and
> - * directories on filesystems where the block size is equal to the page
> - * size. On directories it serves as an inherited hint so we don't
> - * have to check the device for dax support or flush pagecache.
> - */
> - if (fa->fsx_xflags & FS_XFLAG_DAX) {
> - struct xfs_buftarg *target = xfs_inode_buftarg(ip);
> -
> - if (!bdev_dax_supported(target->bt_bdev, sb->s_blocksize))
> - return -EINVAL;
> - }
> -
> - /* If the DAX state is not changing, we have nothing to do here. */
> - if ((fa->fsx_xflags & FS_XFLAG_DAX) && IS_DAX(inode))
> - return 0;
> - if (!(fa->fsx_xflags & FS_XFLAG_DAX) && !IS_DAX(inode))
> - return 0;
> + struct xfs_mount *mp = ip->i_mount;
> + struct inode *inode = VFS_I(ip);
>
> if (S_ISDIR(inode->i_mode))
> - return 0;
> -
> - /* lock, flush and invalidate mapping in preparation for flag change */
> - xfs_ilock(ip, XFS_MMAPLOCK_EXCL | XFS_IOLOCK_EXCL);
> - error = filemap_write_and_wait(inode->i_mapping);
> - if (error)
> - goto out_unlock;
> - error = invalidate_inode_pages2(inode->i_mapping);
> - if (error)
> - goto out_unlock;
> -
> - *join_flags = XFS_MMAPLOCK_EXCL | XFS_IOLOCK_EXCL;
> - return 0;
> + return;
>
> -out_unlock:
> - xfs_iunlock(ip, XFS_MMAPLOCK_EXCL | XFS_IOLOCK_EXCL);
> - return error;
> + if ((mp->m_flags & XFS_MOUNT_DAX_ALWAYS) ||
> + (mp->m_flags & XFS_MOUNT_DAX_NEVER))
> + return;
>
> + if (((fa->fsx_xflags & FS_XFLAG_DAX) &&
> + !(ip->i_d.di_flags2 & XFS_DIFLAG2_DAX)) ||
> + (!(fa->fsx_xflags & FS_XFLAG_DAX) &&
> + (ip->i_d.di_flags2 & XFS_DIFLAG2_DAX)))
> + mark_inode_dontcache(inode);
> }
>
> /*
> @@ -1310,17 +1272,10 @@ xfs_ioctl_setattr_dax_invalidate(
> * have permission to do so. On success, return a clean transaction and the
> * inode locked exclusively ready for further operation specific checks. On
> * failure, return an error without modifying or locking the inode.
> - *
> - * The inode might already be IO locked on call. If this is the case, it is
> - * indicated in @join_flags and we take full responsibility for ensuring they
> - * are unlocked from now on. Hence if we have an error here, we still have to
> - * unlock them. Otherwise, once they are joined to the transaction, they will
> - * be unlocked on commit/cancel.
> */
> static struct xfs_trans *
> xfs_ioctl_setattr_get_trans(
> - struct xfs_inode *ip,
> - int join_flags)
> + struct xfs_inode *ip)
> {
> struct xfs_mount *mp = ip->i_mount;
> struct xfs_trans *tp;
> @@ -1337,8 +1292,7 @@ xfs_ioctl_setattr_get_trans(
> goto out_unlock;
>
> xfs_ilock(ip, XFS_ILOCK_EXCL);
> - xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL | join_flags);
> - join_flags = 0;
> + xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
>
> /*
> * CAP_FOWNER overrides the following restrictions:
> @@ -1359,8 +1313,6 @@ xfs_ioctl_setattr_get_trans(
> out_cancel:
> xfs_trans_cancel(tp);
> out_unlock:
> - if (join_flags)
> - xfs_iunlock(ip, join_flags);
> return ERR_PTR(error);
> }
>
> @@ -1486,7 +1438,6 @@ xfs_ioctl_setattr(
> struct xfs_dquot *pdqp = NULL;
> struct xfs_dquot *olddquot = NULL;
> int code;
> - int join_flags = 0;
>
> trace_xfs_ioctl_setattr(ip);
>
> @@ -1510,18 +1461,9 @@ xfs_ioctl_setattr(
> return code;
> }
>
> - /*
> - * Changing DAX config may require inode locking for mapping
> - * invalidation. These need to be held all the way to transaction commit
> - * or cancel time, so need to be passed through to
> - * xfs_ioctl_setattr_get_trans() so it can apply them to the join call
> - * appropriately.
> - */
> - code = xfs_ioctl_setattr_dax_invalidate(ip, fa, &join_flags);
> - if (code)
> - goto error_free_dquots;
> + xfs_ioctl_dax_check_set_cache(ip, fa);
>
> - tp = xfs_ioctl_setattr_get_trans(ip, join_flags);
> + tp = xfs_ioctl_setattr_get_trans(ip);
> if (IS_ERR(tp)) {
> code = PTR_ERR(tp);
> goto error_free_dquots;
> @@ -1651,7 +1593,6 @@ xfs_ioc_setxflags(
> struct fsxattr fa;
> struct fsxattr old_fa;
> unsigned int flags;
> - int join_flags = 0;
> int error;
>
> if (copy_from_user(&flags, arg, sizeof(flags)))
> @@ -1668,18 +1609,9 @@ xfs_ioc_setxflags(
> if (error)
> return error;
>
> - /*
> - * Changing DAX config may require inode locking for mapping
> - * invalidation. These need to be held all the way to transaction commit
> - * or cancel time, so need to be passed through to
> - * xfs_ioctl_setattr_get_trans() so it can apply them to the join call
> - * appropriately.
> - */
> - error = xfs_ioctl_setattr_dax_invalidate(ip, &fa, &join_flags);
> - if (error)
> - goto out_drop_write;
> + xfs_ioctl_dax_check_set_cache(ip, &fa);
>
> - tp = xfs_ioctl_setattr_get_trans(ip, join_flags);
> + tp = xfs_ioctl_setattr_get_trans(ip);
> if (IS_ERR(tp)) {
> error = PTR_ERR(tp);
> goto out_drop_write;
> --
> 2.25.1
>
