68 lines
2.3 KiB
Diff
68 lines
2.3 KiB
Diff
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From 94a78764d80b6dc41ff2ae8a0e5f1b35c2fd8e78 Mon Sep 17 00:00:00 2001
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From: Nir Soffer <nsoffer@redhat.com>
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Date: Sat, 27 Feb 2021 05:36:38 +0200
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Subject: [PATCH 4/5] copy: file-ops.c: Remove unneeded check
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This function is called only from page_cache_evict(), which already
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check that we could map the cached pages. Add an assert to document this
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assumption.
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Signed-off-by: Nir Soffer <nsoffer@redhat.com>
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---
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copy/file-ops.c | 21 +++++++++++----------
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1 file changed, 11 insertions(+), 10 deletions(-)
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diff --git a/copy/file-ops.c b/copy/file-ops.c
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index ea725a4..47ec768 100644
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--- a/copy/file-ops.c
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+++ b/copy/file-ops.c
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@@ -102,7 +102,7 @@ page_size_init (void)
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/* Load the page cache map for a particular file into
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* rwf->cached_pages. Only used when reading files. This doesn't
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* fail: if a system call fails then rwf->cached_pages.size will be
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- * zero which is handled in page_was_cached.
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+ * zero which is handled in page_cache_evict.
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*/
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static inline void
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page_cache_map (struct rw_file *rwf)
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@@ -126,19 +126,16 @@ page_cache_map (struct rw_file *rwf)
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munmap (ptr, rwf->rw.size);
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}
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-/* Test if a single page of the file was cached before nbdcopy ran. */
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+/* Test if a single page of the file was cached before nbdcopy ran.
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+ * Valid only if we mapped the cached pages.
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+ */
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static inline bool
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page_was_cached (struct rw_file *rwf, uint64_t offset)
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{
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uint64_t page = offset / page_size;
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- if (page < rwf->cached_pages.size)
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- return (rwf->cached_pages.ptr[page] & 1) != 0;
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- else
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- /* This path is taken if we didn't manage to map the input file
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- * for any reason. In this case assume that pages were mapped so
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- * we will not evict them: essentially fall back to doing nothing.
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- */
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- return true;
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+ assert (page < rwf->cached_pages.size);
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+
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+ return (rwf->cached_pages.ptr[page] & 1) != 0;
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}
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/* Evict file contents from the page cache if they were not present in
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@@ -150,6 +147,10 @@ page_cache_evict (struct rw_file *rwf, uint64_t orig_offset, size_t orig_len)
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uint64_t offset, n;
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size_t len;
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+ /* If we didn't manage to map the input file for any reason, assume
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+ * that pages were mapped so we will not evict them: essentially fall
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+ * back to doing nothing.
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+ */
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if (rwf->cached_pages.size == 0) return;
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/* Only bother with whole pages. */
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--
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2.29.0.rc2
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