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Date: Sun, 20 Oct 2019 08:59:35 -0700 From: ira.weiny@...el.com To: linux-kernel@...r.kernel.org Cc: Ira Weiny <ira.weiny@...el.com>, Alexander Viro <viro@...iv.linux.org.uk>, "Darrick J. Wong" <darrick.wong@...cle.com>, Dan Williams <dan.j.williams@...el.com>, Dave Chinner <david@...morbit.com>, Christoph Hellwig <hch@....de>, "Theodore Y. Ts'o" <tytso@....edu>, Jan Kara <jack@...e.cz>, linux-ext4@...r.kernel.org, linux-xfs@...r.kernel.org, linux-fsdevel@...r.kernel.org Subject: [PATCH 5/5] fs/xfs: Allow toggle of physical DAX flag From: Ira Weiny <ira.weiny@...el.com> Switching between DAX and non-DAX on a file is racy with respect to data operations. However, if no data is involved the flag is safe to switch. Allow toggling the physical flag if a file is empty. The file length check is not racy with respect to other operations as it is performed under XFS_MMAPLOCK_EXCL and XFS_IOLOCK_EXCL locks. Signed-off-by: Ira Weiny <ira.weiny@...el.com> --- fs/xfs/xfs_ioctl.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c index d3a7340d3209..3839684c249b 100644 --- a/fs/xfs/xfs_ioctl.c +++ b/fs/xfs/xfs_ioctl.c @@ -33,6 +33,7 @@ #include "xfs_sb.h" #include "xfs_ag.h" #include "xfs_health.h" +#include "libxfs/xfs_dir2.h" #include <linux/mount.h> #include <linux/namei.h> @@ -1232,12 +1233,10 @@ xfs_diflags_to_linux( inode->i_flags |= S_NOATIME; else inode->i_flags &= ~S_NOATIME; -#if 0 /* disabled until the flag switching races are sorted out */ if (xflags & FS_XFLAG_DAX) inode->i_flags |= S_DAX; else inode->i_flags &= ~S_DAX; -#endif } static int @@ -1320,6 +1319,12 @@ xfs_ioctl_setattr_dax_invalidate( /* lock, flush and invalidate mapping in preparation for flag change */ xfs_ilock(ip, XFS_MMAPLOCK_EXCL | XFS_IOLOCK_EXCL); + + if (i_size_read(inode) != 0) { + error = -EOPNOTSUPP; + goto out_unlock; + } + error = filemap_write_and_wait(inode->i_mapping); if (error) goto out_unlock; -- 2.20.1
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