xfs: remove XFS_TRANS_NOFS

Instead of a magic flag for xfs_trans_alloc, just ensure all callers
that can't relclaim through the file system use memalloc_nofs_save to
set the per-task nofs flag.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

1 files changed, 15 insertions, 3 deletions

diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 3041b44e38c6..e93bacbd49ae 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -374,6 +374,7 @@ xfs_dio_write_end_io(
 	struct inode		*inode = file_inode(iocb->ki_filp);
 	struct xfs_inode	*ip = XFS_I(inode);
 	loff_t			offset = iocb->ki_pos;
+	unsigned int		nofs_flag;
 	int			error = 0;
 
 	trace_xfs_end_io_direct_write(ip, offset, size);
@@ -390,10 +391,17 @@ xfs_dio_write_end_io(
 	 */
 	XFS_STATS_ADD(ip->i_mount, xs_write_bytes, size);
 
+	/*
+	 * We can allocate memory here while doing writeback on behalf of
+	 * memory reclaim.  To avoid memory allocation deadlocks set the
+	 * task-wide nofs context for the following operations.
+	 */
+	nofs_flag = memalloc_nofs_save();
+
 	if (flags & IOMAP_DIO_COW) {
 		error = xfs_reflink_end_cow(ip, offset, size);
 		if (error)
-			return error;
+			goto out;
 	}
 
 	/*
@@ -402,8 +410,10 @@ xfs_dio_write_end_io(
 	 * earlier allows a racing dio read to find unwritten extents before
 	 * they are converted.
 	 */
-	if (flags & IOMAP_DIO_UNWRITTEN)
-		return xfs_iomap_write_unwritten(ip, offset, size, true);
+	if (flags & IOMAP_DIO_UNWRITTEN) {
+		error = xfs_iomap_write_unwritten(ip, offset, size, true);
+		goto out;
+	}
 
 	/*
 	 * We need to update the in-core inode size here so that we don't end up
@@ -425,6 +435,8 @@ xfs_dio_write_end_io(
 		spin_unlock(&ip->i_flags_lock);
 	}
 
+out:
+	memalloc_nofs_restore(nofs_flag);
 	return error;
 }