Re: [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&gt; --- 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