This will allow to use all iov_iter based read/write for ITER_KVEC
without having to check if the file has the iter version of the
read/write ops, which will allow us to get rid of a large number
of get_fs/set_fs calls in drivers.
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
fs/read_write.c | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/fs/read_write.c b/fs/read_write.c
index 64b61a032a56..60c64a996ab2 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -704,9 +704,18 @@ static ssize_t do_loop_readv_writev(struct file *filp, struct iov_iter *iter,
loff_t *ppos, int type, int flags)
{
ssize_t ret = 0;
+ mm_segment_t uninitialized_var(old_fs);
if (flags & ~RWF_HIPRI)
return -EOPNOTSUPP;
+ if (iter->type & (ITER_BVEC | ITER_PIPE))
+ return -EOPNOTSUPP;
+
+ /* adjust the address limit for in-kernel I/O */
+ if (iter->type & ITER_KVEC) {
+ old_fs = get_fs();
+ set_fs(get_ds());
+ }
while (iov_iter_count(iter)) {
struct iovec iovec = iov_iter_iovec(iter);
@@ -731,6 +740,8 @@ static ssize_t do_loop_readv_writev(struct file *filp, struct iov_iter *iter,
iov_iter_advance(iter, nr);
}
+ if (iter->type & ITER_KVEC)
+ set_fs(old_fs);
return ret;
}
--
2.11.0
