Add option to ignore-sync for RMAN backup/restore case

CHANGELOG.md

@@ -3,6 +3,7 @@
 
 **Bug Fixes**
 - [#1237](https://github.com/Azure/azure-storage-fuse/issues/1237) Fixed the case sensitivity of content type for file extensions.
+- [#1230](https://github.com/Azure/azure-storage-fuse/issues/1230) Disable deletion of files from local-cache on sync. Use `--ignore-sync` cli option to enable this.
 
 **Optimizations**
 - Optimized file-cache to skip download when O_TRUNC flag is provided in open call.

component/file_cache/file_cache.go

@@ -74,6 +74,7 @@ type FileCache struct {
 	allowOther      bool
 	offloadIO       bool
 	syncToFlush     bool
+	syncToDelete    bool
 	maxCacheSize    float64
 
 	defaultPermission os.FileMode
@@ -105,6 +106,7 @@ type FileCacheOptions struct {
 	V1Timeout     uint32 `config:"file-cache-timeout-in-seconds" yaml:"-"`
 	EmptyDirCheck bool   `config:"empty-dir-check" yaml:"-"`
 	SyncToFlush   bool   `config:"sync-to-flush" yaml:"sync-to-flush,omitempty"`
+	SyncNoOp      bool   `config:"ignore-sync" yaml:"ignore-sync,omitempty"`
 
 	RefreshSec uint32 `config:"refresh-sec" yaml:"refresh-sec,omitempty"`
 }
@@ -229,6 +231,7 @@ func (c *FileCache) Configure(_ bool) error {
 	c.offloadIO = conf.OffloadIO
 	c.maxCacheSize = conf.MaxSizeMB
 	c.syncToFlush = conf.SyncToFlush
+	c.syncToDelete = !conf.SyncNoOp
 	c.refreshSec = conf.RefreshSec
 
 	c.tmpPath = common.ExpandPath(conf.TmpPath)
@@ -322,6 +325,8 @@ func (c *FileCache) OnConfigChange() {
 	c.policyTrace = conf.EnablePolicyTrace
 	c.offloadIO = conf.OffloadIO
 	c.maxCacheSize = conf.MaxSizeMB
+	c.syncToFlush = conf.SyncToFlush
+	c.syncToDelete = !conf.SyncNoOp
 	_ = c.policy.UpdateConfig(c.GetPolicyConfig(conf))
 }
 
@@ -1095,7 +1100,7 @@ func (fc *FileCache) SyncFile(options internal.SyncFileOptions) error {
 	log.Trace("FileCache::SyncFile : handle=%d, path=%s", options.Handle.ID, options.Handle.Path)
 	if fc.syncToFlush {
 		options.Handle.Flags.Set(handlemap.HandleFlagDirty)
-	} else {
+	} else if fc.syncToDelete {
 		err := fc.NextComponent().SyncFile(options)
 		if err != nil {
 			log.Err("FileCache::SyncFile : %s failed", options.Handle.Path)
@@ -1501,6 +1506,9 @@ func init() {
 	syncToFlush := config.AddBoolFlag("sync-to-flush", false, "Sync call on file will force a upload of the file.")
 	config.BindPFlag(compName+".sync-to-flush", syncToFlush)
 
+	ignoreSync := config.AddBoolFlag("ignore-sync", false, "Just ignore sync call and do not invalidate locally cached file.")
+	config.BindPFlag(compName+".ignore-sync", ignoreSync)
+
 	config.RegisterFlagCompletionFunc("tmp-path", func(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
 		return nil, cobra.ShellCompDirectiveDefault
 	})

setup/baseConfig.yaml

@@ -109,7 +109,8 @@ file_cache:
   offload-io: true|false <by default libfuse will service reads/writes to files for better perf. Set to true to make file-cache component service read/write calls.>
   sync-to-flush: true|false <sync call to a file will force upload of the contents to storage account>
   refresh-sec: <number of seconds after which compare lmt of file in local cache and container and refresh file if container has the latest copy>
-
+  ignore-sync: true|false <sync call will be ignored and locally cached file will not be deleted>
+
 # Attribute cache related configuration
 attr_cache:
   timeout-sec: <time attributes can be cached (in sec). Default - 120 sec>