Support bucket versioning (#9377)

- Implement a new xl.json 2.0.0 format to support,
  this moves the entire marshaling logic to POSIX
  layer, top layer always consumes a common FileInfo
  construct which simplifies the metadata reads.
- Implement list object versions
- Migrate to siphash from crchash for new deployments
  for object placements.

Fixes #2111

cmd/storage-errors.go

@@ -1,5 +1,5 @@
 /*
- * MinIO Cloud Storage, (C) 2015, 2016 MinIO, Inc.
+ * MinIO Cloud Storage, (C) 2015-2020 MinIO, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,6 +16,8 @@
 
 package cmd
 
+import "os"
+
 // errUnexpected - unexpected error, requires manual intervention.
 var errUnexpected = StorageErr("Unexpected error, please report this issue at https://github.com/minio/minio/issues")
 
@@ -31,6 +33,9 @@ var errUnsupportedDisk = StorageErr("disk does not support O_DIRECT")
 // errDiskFull - cannot create volume or files when disk is full.
 var errDiskFull = StorageErr("disk path full")
 
+// errDiskNotDir - cannot use storage disk if its not a directory
+var errDiskNotDir = StorageErr("disk is not directory or mountpoint")
+
 // errDiskNotFound - cannot find the underlying configured disk anymore.
 var errDiskNotFound = StorageErr("disk not found")
 
@@ -46,6 +51,9 @@ var errDiskAccessDenied = StorageErr("disk access denied")
 // errFileNotFound - cannot find the file.
 var errFileNotFound = StorageErr("file not found")
 
+// errFileNotFound - cannot find requested file version.
+var errFileVersionNotFound = StorageErr("file version not found")
+
 // errTooManyOpenFiles - too many open files.
 var errTooManyOpenFiles = StorageErr("too many open files")
 
@@ -92,7 +100,7 @@ var errLessData = StorageErr("less data available than what was requested")
 // errMoreData = returned when more data was sent by the caller than what it was supposed to.
 var errMoreData = StorageErr("more data was sent than what was advertised")
 
-// StorageErr represents error generated by posix call.
+// StorageErr represents error generated by xlStorage call.
 type StorageErr string
 
 func (h StorageErr) Error() string {
@@ -107,3 +115,32 @@ var baseErrs = []error{
 }
 
 var baseIgnoredErrs = baseErrs
+
+// Is a one place function which converts all os.PathError
+// into a more FS object layer friendly form, converts
+// known errors into their typed form for top level
+// interpretation.
+func osErrToFileErr(err error) error {
+	if err == nil {
+		return nil
+	}
+	if os.IsNotExist(err) {
+		return errFileNotFound
+	}
+	if os.IsPermission(err) {
+		return errFileAccessDenied
+	}
+	if isSysErrNotDir(err) {
+		return errFileNotFound
+	}
+	if isSysErrPathNotFound(err) {
+		return errFileNotFound
+	}
+	if isSysErrTooManyFiles(err) {
+		return errTooManyOpenFiles
+	}
+	if isSysErrHandleInvalid(err) {
+		return errFileNotFound
+	}
+	return err
+}