6.5-stable review patch. If anyone has any objections, please let me know.
------------------
From: Al Viro viro@zeniv.linux.org.uk
[ Upstream commit 8287474aa5ffb41df52552c4ae4748e791d2faf2 ]
If we fail filemap_write_and_wait_range() on the range the buffered write went into, we only report the "number of bytes which we direct-written", to quote the comment in there. Which is fine, but buffered write has already advanced iocb->ki_pos, so we need to roll that back. Otherwise we end up with e.g. write(2) advancing position by more than the amount it reports having written.
Fixes: 182c25e9c157 "filemap: update ki_pos in generic_perform_write" Signed-off-by: Al Viro viro@zeniv.linux.org.uk Message-Id: 20230827214518.GU3390869@ZenIV Signed-off-by: Christian Brauner brauner@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- fs/libfs.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/fs/libfs.c b/fs/libfs.c index 5b851315eeed0..712c57828c0e4 100644 --- a/fs/libfs.c +++ b/fs/libfs.c @@ -1646,6 +1646,7 @@ ssize_t direct_write_fallback(struct kiocb *iocb, struct iov_iter *iter, * We don't know how much we wrote, so just return the number of * bytes which were direct-written */ + iocb->ki_pos -= buffered_written; if (direct_written) return direct_written; return err;