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Message-ID: <20200602172353.GC8230@magnolia> Date: Tue, 2 Jun 2020 10:23:53 -0700 From: "Darrick J. Wong" <darrick.wong@...cle.com> To: ira.weiny@...el.com Cc: linux-kernel@...r.kernel.org, linux-xfs@...r.kernel.org, Al Viro <viro@...iv.linux.org.uk>, Jan Kara <jack@...e.cz>, Dan Williams <dan.j.williams@...el.com>, Dave Chinner <david@...morbit.com>, Christoph Hellwig <hch@....de>, "Theodore Y. Ts'o" <tytso@....edu>, Jeff Moyer <jmoyer@...hat.com>, linux-ext4@...r.kernel.org, linux-fsdevel@...r.kernel.org, linux-api@...r.kernel.org Subject: Re: [PATCH V11 11/11] fs/xfs: Update xfs_ioctl_setattr_dax_invalidate() On Tue, Apr 28, 2020 at 01:11:38PM -0700, Darrick J. Wong wrote: > On Mon, Apr 27, 2020 at 05:21:42PM -0700, ira.weiny@...el.com wrote: > > From: Ira Weiny <ira.weiny@...el.com> > > > > 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@...el.com> > > Looks ok, > Reviewed-by: Darrick J. Wong <darrick.wong@...cle.com> > > --D > > > > > --- > > Changes from V10: > > adjust for renamed d_mark_dontcache() function > > > > Changes from V9: > > Change name of function to xfs_ioctl_setattr_prepare_dax() > > > > 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..ff474f2c9acf 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_setattr_prepare_dax( > > 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))) > > + d_mark_dontcache(inode); Now that I think about this further, are we /really/ sure that we want to let unprivileged userspace cause inode evictions? --D > > } > > > > /* > > @@ -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_setattr_prepare_dax(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_setattr_prepare_dax(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 > >
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