[Libguestfs] [PATCH libnbd 2/4] copy: file-ops.c: Remove unneeded check
This function is called only from page_cache_evict(), which already
check that we could map the cached pages. Add an assert to document this
assumption.
Signed-off-by: Nir Soffer <nsoffer(a)redhat.com>
---
copy/file-ops.c | 21 +++++++++++----------
1 file changed, 11 insertions(+), 10 deletions(-)
diff --git a/copy/file-ops.c b/copy/file-ops.c
index 0995e92..57999cb 100644
--- a/copy/file-ops.c
+++ b/copy/file-ops.c
@@ -94,7 +94,7 @@ page_size_init (void)
/* Load the page cache map for a particular file into
* rwf->cached_pages. Only used when reading files. This doesn't
* fail: if a system call fails then rwf->cached_pages.size will be
- * zero which is handled in page_was_cached.
+ * zero which is handled in page_cache_evict.
*/
static inline void
page_cache_map (struct rw_file *rwf, int fd, int64_t size)
@@ -118,19 +118,16 @@ page_cache_map (struct rw_file *rwf, int fd, int64_t size)
munmap (ptr, size);
}
-/* Test if a single page of the file was cached before nbdcopy ran. */
+/* Test if a single page of the file was cached before nbdcopy ran.
+ * Valid only if we mapped the cached pages.
+ */
static inline bool
page_was_cached (struct rw_file *rwf, uint64_t offset)
{
uint64_t page = offset / page_size;
- if (page < rwf->cached_pages.size)
- return (rwf->cached_pages.ptr[page] & 1) != 0;
- else
- /* This path is taken if we didn't manage to map the input file
- * for any reason. In this case assume that pages were mapped so
- * we will not evict them: essentially fall back to doing nothing.
- */
- return true;
+ assert (page < rwf->cached_pages.size);
+
+ return (rwf->cached_pages.ptr[page] & 1) != 0;
}
/* Evict file contents from the page cache if they were not present in
@@ -142,6 +139,10 @@ page_cache_evict (struct rw_file *rwf, uint64_t orig_offset, size_t
orig_len)
uint64_t offset, n;
size_t len;
+ /* If we didn't manage to map the input file for any reason, assume
+ * that pages were mapped so we will not evict them: essentially fall
+ * back to doing nothing.
+ */
if (rwf->cached_pages.size == 0) return;
/* Only bother with whole pages. */
--
2.26.2