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[v2,1/2] iov_iter: mark truncated iters

Message ID 69fd298bc71bb80ac5a639e10890a5b7175e566c.1628780390.git.asml.silence@gmail.com (mailing list archive)
State New, archived
Headers show
Series iter revert problems | expand

Commit Message

Pavel Begunkov Aug. 12, 2021, 8:40 p.m. UTC 
Track if an iterator has ever been truncated. This will be used to
mitigate revert-truncate problems.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
 include/linux/uio.h | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)
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Patch

diff --git a/include/linux/uio.h b/include/linux/uio.h
index 82c3c3e819e0..61b8d312d13a 100644
--- a/include/linux/uio.h
+++ b/include/linux/uio.h
@@ -30,6 +30,7 @@  enum iter_type {
 struct iov_iter {
 	u8 iter_type;
 	bool data_source;
+	bool truncated;
 	size_t iov_offset;
 	size_t count;
 	union {
@@ -254,8 +255,10 @@  static inline void iov_iter_truncate(struct iov_iter *i, u64 count)
 	 * conversion in assignement is by definition greater than all
 	 * values of size_t, including old i->count.
 	 */
-	if (i->count > count)
+	if (i->count > count) {
 		i->count = count;
+		i->truncated = true;
+	}
 }
 
 /*