Differential D9502 Diff 22912 files/0003-stream-file-use-fstat-instead-of-lseek-to-determine-file-size.patch

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				From 20eead18130fd460d8e9eff50ce14afd3646faab Mon Sep 17 00:00:00 2001
				From: wm4 <wm4@nowhere>
				Date: Sun, 16 Feb 2020 23:36:05 +0100
				Subject: [PATCH] stream_file: use fstat() instead of lseek() to determine file
				size

				It appears using lseek() to seek to the end and back to determine file
				size is inefficient in some cases.

				With CIFS, this restores the performance regression that happened when
				the stream cache was removed (which called read() from a thread). This
				is probably faster than the old code too, because it's the seeking that
				was slowing down CIFS.

				According to the user who tested this, the size caching does not help
				with fstat() (although it did with the old method).

				Fixes: #7408, #7152
				---
				stream/stream_file.c \| 11 ++++++++---
				1 file changed, 8 insertions(+), 3 deletions(-)

				diff --git a/stream/stream_file.c b/stream/stream_file.c
				index 6e69f33c94..9f83b73dd1 100644
				--- a/stream/stream_file.c
				+++ b/stream/stream_file.c
				@@ -77,9 +77,14 @@ static int64_t get_size(stream_t *s)
				{
				struct priv *p = s->priv;
				if (p->cached_size == -2) {
				- off_t size = lseek(p->fd, 0, SEEK_END);
				- lseek(p->fd, s->pos, SEEK_SET);
				- p->cached_size = size < 0 ? -1 : size;
				+ int64_t size = -1;
				+ struct stat st;
				+ if (fstat(p->fd, &st) == 0) {
				+ if (st.st_size <= 0 && !s->seekable)
				+ st.st_size = -1;
				+ size = st.st_size < 0 ? -1 : st.st_size;
				+ }
				+ p->cached_size = size;
				}
				return p->cached_size;
				}