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authorRaghavendra G <rgowdapp@redhat.com>2018-06-15 17:01:38 +0530
committerRaghavendra G <rgowdapp@redhat.com>2018-06-18 09:37:08 +0000
commit67de708df134cc9f2edf408f2dd9a7ed1a1ef817 (patch)
tree01cdbe04a78823ac4c70dc3122b5286332921d61 /xlators/performance/quick-read/src
parentce8290db83427535b532c6df72ef07fae89407eb (diff)
performance/quick-read: provide an invalidation based on ctime
Quick-read by default uses mtime to identify changes to file data. However there are applications like rsync which explicitly set mtime making it unreliable for the purpose of identifying change in file content. Since ctime also changes when content of a file changes and it cannot be set explicitly, it becomes suitable for identifying staleness of cached data. This option makes quick-read to prefer ctime over mtime to validate its cache. However, using ctime can result in false positives as ctime changes with just attribute changes like permission without changes to file data. So, use this option only when mtime is not reliable. credits to Kotresh Hiremath Ravishankar <khiremat@redhat.com> for suggestion on using ctime instead of mtime. Change-Id: Ib3ae39a3252b2876c8ffe81f471d02a87190e9b9 Signed-off-by: Raghavendra G <rgowdapp@redhat.com> Updates: bz#1591621
Diffstat (limited to 'xlators/performance/quick-read/src')
-rw-r--r--xlators/performance/quick-read/src/quick-read.c47
-rw-r--r--xlators/performance/quick-read/src/quick-read.h3
2 files changed, 49 insertions, 1 deletions
diff --git a/xlators/performance/quick-read/src/quick-read.c b/xlators/performance/quick-read/src/quick-read.c
index c3581783365..d26742b0c5e 100644
--- a/xlators/performance/quick-read/src/quick-read.c
+++ b/xlators/performance/quick-read/src/quick-read.c
@@ -334,6 +334,8 @@ qr_content_update (xlator_t *this, qr_inode_t *qr_inode, void *data,
qr_inode->ia_mtime = buf->ia_mtime;
qr_inode->ia_mtime_nsec = buf->ia_mtime_nsec;
+ qr_inode->ia_ctime = buf->ia_ctime;
+ qr_inode->ia_ctime_nsec = buf->ia_ctime_nsec;
qr_inode->buf = *buf;
@@ -363,6 +365,24 @@ qr_mtime_equal (qr_inode_t *qr_inode, struct iatt *buf)
}
+gf_boolean_t
+qr_ctime_equal (qr_inode_t *qr_inode, struct iatt *buf)
+{
+ return (qr_inode->ia_ctime == buf->ia_ctime &&
+ qr_inode->ia_ctime_nsec == buf->ia_ctime_nsec);
+}
+
+
+gf_boolean_t
+qr_time_equal (qr_conf_t *conf, qr_inode_t *qr_inode, struct iatt *buf)
+{
+ if (conf->ctime_invalidation)
+ return qr_ctime_equal (qr_inode, buf);
+ else
+ return qr_mtime_equal (qr_inode, buf);
+}
+
+
void
__qr_content_refresh (xlator_t *this, qr_inode_t *qr_inode, struct iatt *buf,
uint64_t gen)
@@ -381,7 +401,7 @@ __qr_content_refresh (xlator_t *this, qr_inode_t *qr_inode, struct iatt *buf,
qr_inode->gen = gen;
- if (qr_size_fits (conf, buf) && qr_mtime_equal (qr_inode, buf)) {
+ if (qr_size_fits (conf, buf) && qr_time_equal (conf, qr_inode, buf)) {
qr_inode->buf = *buf;
gettimeofday (&qr_inode->last_refresh, NULL);
@@ -981,6 +1001,9 @@ qr_reconfigure (xlator_t *this, dict_t *options)
GF_OPTION_RECONF ("cache-invalidation", conf->qr_invalidation, options,
bool, out);
+ GF_OPTION_RECONF ("ctime-invalidation", conf->ctime_invalidation,
+ options, bool, out);
+
GF_OPTION_RECONF ("cache-size", cache_size_new, options, size_uint64, out);
if (!check_cache_size_ok (this, cache_size_new)) {
ret = -1;
@@ -1136,6 +1159,9 @@ qr_init (xlator_t *this)
goto out;
}
+ GF_OPTION_INIT ("ctime-invalidation", conf->ctime_invalidation, bool,
+ out);
+
INIT_LIST_HEAD (&conf->priority_list);
conf->max_pri = 1;
if (dict_get (this->options, "priority")) {
@@ -1383,6 +1409,25 @@ struct volume_options qr_options[] = {
.description = "When \"on\", invalidates/updates the metadata cache,"
" on receiving the cache-invalidation notifications",
},
+ { .key = {"ctime-invalidation"},
+ .type = GF_OPTION_TYPE_BOOL,
+ .default_value = "false",
+ .op_version = {GD_OP_VERSION_4_2_0},
+ .flags = OPT_FLAG_CLIENT_OPT | OPT_FLAG_SETTABLE | OPT_FLAG_DOC,
+ .description = "Quick-read by default uses mtime to identify changes "
+ "to file data. However there are applications like "
+ "rsync which explicitly set mtime making it unreliable "
+ "for the purpose of identifying change in file content "
+ ". Since ctime also changes when content of a file "
+ " changes and it cannot be set explicitly, it becomes "
+ " suitable for identifying staleness of cached data. "
+ "This option makes quick-read to prefer ctime over "
+ "mtime to validate its cache. However, using ctime "
+ "can result in false positives as ctime changes with "
+ "just attribute changes like permission without "
+ "changes to file data. So, use this only when mtime "
+ "is not reliable",
+ },
{ .key = {NULL} }
};
diff --git a/xlators/performance/quick-read/src/quick-read.h b/xlators/performance/quick-read/src/quick-read.h
index cdbf3dfbd63..8ef0f9802b8 100644
--- a/xlators/performance/quick-read/src/quick-read.h
+++ b/xlators/performance/quick-read/src/quick-read.h
@@ -36,6 +36,8 @@ struct qr_inode {
int priority;
uint32_t ia_mtime;
uint32_t ia_mtime_nsec;
+ uint32_t ia_ctime;
+ uint32_t ia_ctime_nsec;
struct iatt buf;
struct timeval last_refresh;
struct list_head lru;
@@ -57,6 +59,7 @@ struct qr_conf {
uint64_t cache_size;
int max_pri;
gf_boolean_t qr_invalidation;
+ gf_boolean_t ctime_invalidation;
struct list_head priority_list;
};
typedef struct qr_conf qr_conf_t;