b4d42fa29b
Add nbdkit-cow-filter cow-on-read option. Add nbdkit-cache-filter cache-on-read=/PATH. Add nbdkit-cache-filter cache-min-block-size option. Add nbdkit-delay-filter delay-open and delay-close options. Reduce verbosity of debugging from virt-v2v. Miscellaneous bugfixes resolves: rhbz#1950632
152 lines
5.0 KiB
Diff
152 lines
5.0 KiB
Diff
From b7fe9b7b6c6d317291c76f15910215828bbfd4ff Mon Sep 17 00:00:00 2001
|
|
From: "Richard W.M. Jones" <rjones@redhat.com>
|
|
Date: Mon, 26 Jul 2021 16:16:15 +0100
|
|
Subject: [PATCH] cache: Implement cache-on-read=/PATH
|
|
|
|
For virt-v2v we will need to be able to turn cache-on-read on while
|
|
performing inspection and modification of the guest, and off when
|
|
doing the bulk copy. To do that allow the cache-on-read parameter to
|
|
refer to a path where the existence of the path toggles the feature.
|
|
|
|
(We could restart nbdkit between these phases, but this change avoids
|
|
doing that.)
|
|
|
|
(cherry picked from commit c8b575241b15b3bf0adaf15313e67e5ed4270b5a)
|
|
---
|
|
filters/cache/blk.c | 2 +-
|
|
filters/cache/cache.c | 33 ++++++++++++++++++++-------
|
|
filters/cache/cache.h | 10 ++++++--
|
|
filters/cache/nbdkit-cache-filter.pod | 11 ++++++++-
|
|
4 files changed, 44 insertions(+), 12 deletions(-)
|
|
|
|
diff --git a/filters/cache/blk.c b/filters/cache/blk.c
|
|
index 42bd3779..19f79605 100644
|
|
--- a/filters/cache/blk.c
|
|
+++ b/filters/cache/blk.c
|
|
@@ -244,7 +244,7 @@ _blk_read_multiple (nbdkit_next *next,
|
|
memset (block + n, 0, tail);
|
|
|
|
/* If cache-on-read, copy the blocks to the cache. */
|
|
- if (cache_on_read) {
|
|
+ if (cache_on_read ()) {
|
|
if (cache_debug_verbose)
|
|
nbdkit_debug ("cache: cache-on-read block %" PRIu64
|
|
" (offset %" PRIu64 ")",
|
|
diff --git a/filters/cache/cache.c b/filters/cache/cache.c
|
|
index 9c081948..8af52106 100644
|
|
--- a/filters/cache/cache.c
|
|
+++ b/filters/cache/cache.c
|
|
@@ -74,7 +74,8 @@ unsigned blksize;
|
|
enum cache_mode cache_mode = CACHE_MODE_WRITEBACK;
|
|
int64_t max_size = -1;
|
|
unsigned hi_thresh = 95, lo_thresh = 80;
|
|
-bool cache_on_read = false;
|
|
+enum cor_mode cor_mode = COR_OFF;
|
|
+const char *cor_path;
|
|
|
|
static int cache_flush (nbdkit_next *next, void *handle, uint32_t flags,
|
|
int *err);
|
|
@@ -161,12 +162,16 @@ cache_config (nbdkit_next_config *next, nbdkit_backend *nxdata,
|
|
}
|
|
#endif /* !HAVE_CACHE_RECLAIM */
|
|
else if (strcmp (key, "cache-on-read") == 0) {
|
|
- int r;
|
|
-
|
|
- r = nbdkit_parse_bool (value);
|
|
- if (r == -1)
|
|
- return -1;
|
|
- cache_on_read = r;
|
|
+ if (value[0] == '/') {
|
|
+ cor_path = value;
|
|
+ cor_mode = COR_PATH;
|
|
+ }
|
|
+ else {
|
|
+ int r = nbdkit_parse_bool (value);
|
|
+ if (r == -1)
|
|
+ return -1;
|
|
+ cor_mode = r ? COR_ON : COR_OFF;
|
|
+ }
|
|
return 0;
|
|
}
|
|
else {
|
|
@@ -177,7 +182,7 @@ cache_config (nbdkit_next_config *next, nbdkit_backend *nxdata,
|
|
#define cache_config_help_common \
|
|
"cache=MODE Set cache MODE, one of writeback (default),\n" \
|
|
" writethrough, or unsafe.\n" \
|
|
- "cache-on-read=BOOL Set to true to cache on reads (default false).\n"
|
|
+ "cache-on-read=BOOL|/PATH Set to true to cache on reads (default false).\n"
|
|
#ifndef HAVE_CACHE_RECLAIM
|
|
#define cache_config_help cache_config_help_common
|
|
#else
|
|
@@ -187,6 +192,18 @@ cache_config (nbdkit_next_config *next, nbdkit_backend *nxdata,
|
|
"cache-low-threshold=PCT Percentage of max size where reclaim ends.\n"
|
|
#endif
|
|
|
|
+/* Decide if cache-on-read is currently on or off. */
|
|
+bool
|
|
+cache_on_read (void)
|
|
+{
|
|
+ switch (cor_mode) {
|
|
+ case COR_ON: return true;
|
|
+ case COR_OFF: return false;
|
|
+ case COR_PATH: return access (cor_path, F_OK) == 0;
|
|
+ default: abort ();
|
|
+ }
|
|
+}
|
|
+
|
|
static int
|
|
cache_config_complete (nbdkit_next_config_complete *next,
|
|
nbdkit_backend *nxdata)
|
|
diff --git a/filters/cache/cache.h b/filters/cache/cache.h
|
|
index 2b72221f..a559adef 100644
|
|
--- a/filters/cache/cache.h
|
|
+++ b/filters/cache/cache.h
|
|
@@ -49,7 +49,13 @@ extern unsigned blksize;
|
|
extern int64_t max_size;
|
|
extern unsigned hi_thresh, lo_thresh;
|
|
|
|
-/* Cache read requests. */
|
|
-extern bool cache_on_read;
|
|
+/* Cache on read mode. */
|
|
+extern enum cor_mode {
|
|
+ COR_OFF,
|
|
+ COR_ON,
|
|
+ COR_PATH,
|
|
+} cor_mode;
|
|
+extern const char *cor_path;
|
|
+extern bool cache_on_read (void);
|
|
|
|
#endif /* NBDKIT_CACHE_H */
|
|
diff --git a/filters/cache/nbdkit-cache-filter.pod b/filters/cache/nbdkit-cache-filter.pod
|
|
index 34fd0b29..2ac307e0 100644
|
|
--- a/filters/cache/nbdkit-cache-filter.pod
|
|
+++ b/filters/cache/nbdkit-cache-filter.pod
|
|
@@ -8,7 +8,7 @@ nbdkit-cache-filter - nbdkit caching filter
|
|
[cache-max-size=SIZE]
|
|
[cache-high-threshold=N]
|
|
[cache-low-threshold=N]
|
|
- [cache-on-read=true|false]
|
|
+ [cache-on-read=true|false|/PATH]
|
|
[plugin-args...]
|
|
|
|
=head1 DESCRIPTION
|
|
@@ -87,6 +87,15 @@ the plugin.
|
|
|
|
Do not cache read requests (this is the default).
|
|
|
|
+=item B<cache-on-read=/PATH>
|
|
+
|
|
+(nbdkit E<ge> 1.28)
|
|
+
|
|
+When F</PATH> (which must be an absolute path) exists, this behaves
|
|
+like C<cache-on-read=true>, and when it does not exist like
|
|
+C<cache-on-read=false>. This allows you to control the cache-on-read
|
|
+behaviour while nbdkit is running.
|
|
+
|
|
=back
|
|
|
|
=head1 CACHE MAXIMUM SIZE
|
|
--
|
|
2.31.1
|
|
|