cache: Rewrite to cache only on download (#7575)

This will allow cache to consistently work for server and gateways. Range GET requests will be cached in the background after the request is served from the backend. Fixes: #7458, #7573, #6265, #6630
2024-12-23 21:55:53 -05:00 · 2019-05-21 20:00:27 -07:00 · 2019-05-21 20:00:27 -07:00 · a13b58f630
commit a13b58f630
parent 9e7a19d6b9
10 changed files with 754 additions and 1506 deletions
--- a/cmd/bucket-handlers-listobjects.go
+++ b/cmd/bucket-handlers-listobjects.go
@ -100,9 +100,7 @@ func (api objectAPIHandlers) ListObjectsV2Handler(w http.ResponseWriter, r *http
 	}

 	listObjectsV2 := objectAPI.ListObjectsV2
-	if api.CacheAPI() != nil {
-		listObjectsV2 = api.CacheAPI().ListObjectsV2
-	}
+
 	// Inititate a list objects operation based on the input params.
 	// On success would return back ListObjectsInfo object to be
 	// marshaled into S3 compatible XML header.
@ -179,9 +177,6 @@ func (api objectAPIHandlers) ListObjectsV1Handler(w http.ResponseWriter, r *http
 	}

 	listObjects := objectAPI.ListObjects
-	if api.CacheAPI() != nil {
-		listObjects = api.CacheAPI().ListObjects
-	}

 	// Inititate a list objects operation based on the input params.
 	// On success would return back ListObjectsInfo object to be
--- a/cmd/bucket-handlers.go
+++ b/cmd/bucket-handlers.go
@ -105,9 +105,7 @@ func (api objectAPIHandlers) GetBucketLocationHandler(w http.ResponseWriter, r *
 	}

 	getBucketInfo := objectAPI.GetBucketInfo
-	if api.CacheAPI() != nil {
-		getBucketInfo = api.CacheAPI().GetBucketInfo
-	}
+
 	if _, err := getBucketInfo(ctx, bucket); err != nil {
 		writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL, guessIsBrowserReq(r))
 		return
@ -202,9 +200,6 @@ func (api objectAPIHandlers) ListBucketsHandler(w http.ResponseWriter, r *http.R
 	}

 	listBuckets := objectAPI.ListBuckets
-	if api.CacheAPI() != nil {
-		listBuckets = api.CacheAPI().ListBuckets
-	}

 	if s3Error := checkRequestAuthType(ctx, r, policy.ListAllMyBucketsAction, "", ""); s3Error != ErrNone {
 		writeErrorResponse(ctx, w, errorCodes.ToAPIErr(s3Error), r.URL, guessIsBrowserReq(r))
@ -742,9 +737,7 @@ func (api objectAPIHandlers) HeadBucketHandler(w http.ResponseWriter, r *http.Re
 	}

 	getBucketInfo := objectAPI.GetBucketInfo
-	if api.CacheAPI() != nil {
-		getBucketInfo = api.CacheAPI().GetBucketInfo
-	}
+
 	if _, err := getBucketInfo(ctx, bucket); err != nil {
 		writeErrorResponseHeadersOnly(w, toAPIError(ctx, err))
 		return
@ -774,9 +767,7 @@ func (api objectAPIHandlers) DeleteBucketHandler(w http.ResponseWriter, r *http.
 	}

 	deleteBucket := objectAPI.DeleteBucket
-	if api.CacheAPI() != nil {
-		deleteBucket = api.CacheAPI().DeleteBucket
-	}
+
 	// Attempt to delete bucket.
 	if err := deleteBucket(ctx, bucket); err != nil {
 		writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL, guessIsBrowserReq(r))
--- a/cmd/disk-cache-backend.go
+++ b/cmd/disk-cache-backend.go
@ -0,0 +1,417 @@
+/*
+ * MinIO Cloud Storage, (C) 2019 MinIO, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package cmd
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"log"
+	"net/http"
+	"os"
+	"path"
+	"sync"
+	"time"
+
+	"github.com/djherbis/atime"
+	"github.com/minio/minio/cmd/logger"
+	"github.com/minio/minio/pkg/disk"
+)
+
+const (
+	// cache.json object metadata for cached objects.
+	cacheMetaJSONFile = "cache.json"
+	cacheDataFile     = "data"
+
+	cacheEnvDelimiter = ";"
+)
+
+// Represents the cache metadata struct
+type cacheMeta struct {
+	// Metadata map for current object.
+	Meta map[string]string `json:"meta,omitempty"`
+}
+
+func (m *cacheMeta) ToObjectInfo(bucket, object string, fi os.FileInfo) (o ObjectInfo) {
+	if len(m.Meta) == 0 {
+		m.Meta = make(map[string]string)
+	}
+
+	o = ObjectInfo{
+		Bucket: bucket,
+		Name:   object,
+	}
+
+	// We set file info only if its valid.
+	o.ModTime = timeSentinel
+	if fi != nil {
+		o.ModTime = fi.ModTime()
+		o.Size = fi.Size()
+		if fi.IsDir() {
+			// Directory is always 0 bytes in S3 API, treat it as such.
+			o.Size = 0
+			o.IsDir = fi.IsDir()
+		}
+	}
+
+	o.ETag = extractETag(m.Meta)
+	o.ContentType = m.Meta["content-type"]
+	o.ContentEncoding = m.Meta["content-encoding"]
+	if storageClass, ok := m.Meta[amzStorageClass]; ok {
+		o.StorageClass = storageClass
+	} else {
+		o.StorageClass = globalMinioDefaultStorageClass
+	}
+	var (
+		t time.Time
+		e error
+	)
+	if exp, ok := m.Meta["expires"]; ok {
+		if t, e = time.Parse(http.TimeFormat, exp); e == nil {
+			o.Expires = t.UTC()
+		}
+	}
+	// etag/md5Sum has already been extracted. We need to
+	// remove to avoid it from appearing as part of
+	o.UserDefined = cleanMetadata(m.Meta)
+	return o
+}
+
+// disk cache
+type diskCache struct {
+	dir             string // caching directory
+	maxDiskUsagePct int    // max usage in %
+	expiry          int    // cache expiry in days
+	// to manage cache operations
+	nsMutex *nsLockMap
+	// mark false if drive is offline
+	online bool
+	// mutex to protect updates to online variable
+	onlineMutex *sync.RWMutex
+	// purge() listens on this channel to start the cache-purge process
+	purgeChan chan struct{}
+}
+
+// Inits the disk cache dir if it is not init'ed already.
+func newdiskCache(dir string, expiry int, maxDiskUsagePct int) (*diskCache, error) {
+	if err := os.MkdirAll(dir, 0777); err != nil {
+		return nil, fmt.Errorf("Unable to initialize '%s' dir, %s", dir, err)
+	}
+
+	if expiry == 0 {
+		expiry = globalCacheExpiry
+	}
+
+	cache := diskCache{
+		dir:             dir,
+		expiry:          expiry,
+		maxDiskUsagePct: maxDiskUsagePct,
+		purgeChan:       make(chan struct{}),
+		online:          true,
+		onlineMutex:     &sync.RWMutex{},
+		nsMutex:         newNSLock(false),
+	}
+	return &cache, nil
+}
+
+// Returns if the disk usage is low.
+// Disk usage is low if usage is < 80% of cacheMaxDiskUsagePct
+// Ex. for a 100GB disk, if maxUsage is configured as 70% then cacheMaxDiskUsagePct is 70G
+// hence disk usage is low if the disk usage is less than 56G (because 80% of 70G is 56G)
+func (c *diskCache) diskUsageLow() bool {
+	minUsage := c.maxDiskUsagePct * 80 / 100
+	di, err := disk.GetInfo(c.dir)
+	if err != nil {
+		reqInfo := (&logger.ReqInfo{}).AppendTags("cachePath", c.dir)
+		ctx := logger.SetReqInfo(context.Background(), reqInfo)
+		logger.LogIf(ctx, err)
+		return false
+	}
+	usedPercent := (di.Total - di.Free) * 100 / di.Total
+	return int(usedPercent) < minUsage
+}
+
+// Return if the disk usage is high.
+// Disk usage is high if disk used is > cacheMaxDiskUsagePct
+func (c *diskCache) diskUsageHigh() bool {
+	di, err := disk.GetInfo(c.dir)
+	if err != nil {
+		reqInfo := (&logger.ReqInfo{}).AppendTags("cachePath", c.dir)
+		ctx := logger.SetReqInfo(context.Background(), reqInfo)
+		logger.LogIf(ctx, err)
+		return true
+	}
+	usedPercent := (di.Total - di.Free) * 100 / di.Total
+	return int(usedPercent) > c.maxDiskUsagePct
+}
+
+// Returns if size space can be allocated without exceeding
+// max disk usable for caching
+func (c *diskCache) diskAvailable(size int64) bool {
+	di, err := disk.GetInfo(c.dir)
+	if err != nil {
+		reqInfo := (&logger.ReqInfo{}).AppendTags("cachePath", c.dir)
+		ctx := logger.SetReqInfo(context.Background(), reqInfo)
+		logger.LogIf(ctx, err)
+		return false
+	}
+	usedPercent := (di.Total - (di.Free - uint64(size))) * 100 / di.Total
+	return int(usedPercent) < c.maxDiskUsagePct
+}
+
+// Purge cache entries that were not accessed.
+func (c *diskCache) purge() {
+	ctx := context.Background()
+	for {
+		olderThan := c.expiry
+		for !c.diskUsageLow() {
+			// delete unaccessed objects older than expiry duration
+			expiry := UTCNow().AddDate(0, 0, -1*olderThan)
+			olderThan /= 2
+			if olderThan < 1 {
+				break
+			}
+			deletedCount := 0
+
+			objDirs, err := ioutil.ReadDir(c.dir)
+			if err != nil {
+				log.Fatal(err)
+			}
+
+			for _, obj := range objDirs {
+				var fi os.FileInfo
+				fi, err := os.Stat(pathJoin(c.dir, obj.Name()))
+				if err != nil {
+					continue
+				}
+				objInfo, err := c.statCache(ctx, pathJoin(c.dir, obj.Name()))
+				if err != nil {
+					continue
+				}
+				if !filterFromCache(objInfo.UserDefined) ||
+					!isStaleCache(objInfo) ||
+					atime.Get(fi).After(expiry) {
+					continue
+				}
+				if err = os.RemoveAll(pathJoin(c.dir, obj.Name())); err != nil {
+					logger.LogIf(ctx, err)
+					continue
+				}
+				deletedCount++
+			}
+			if deletedCount == 0 {
+				// to avoid a busy loop
+				time.Sleep(time.Minute * 30)
+			}
+		}
+		<-c.purgeChan
+	}
+}
+
+// sets cache drive status
+func (c *diskCache) setOnline(status bool) {
+	c.onlineMutex.Lock()
+	c.online = status
+	c.onlineMutex.Unlock()
+}
+
+// returns true if cache drive is online
+func (c *diskCache) IsOnline() bool {
+	c.onlineMutex.RLock()
+	defer c.onlineMutex.RUnlock()
+	return c.online
+}
+
+// Stat returns ObjectInfo from disk cache
+func (c *diskCache) Stat(ctx context.Context, bucket, object string) (oi ObjectInfo, err error) {
+	cachePath := c.getCacheSHADir(bucket, object)
+	cLock := c.nsMutex.NewNSLock(cachePath, "")
+	if err := cLock.GetRLock(globalObjectTimeout); err != nil {
+		return oi, err
+	}
+	defer cLock.RUnlock()
+
+	oi, err = c.stat(ctx, bucket, object)
+	return
+}
+
+// lockless helper to Stat
+func (c *diskCache) stat(ctx context.Context, bucket, object string) (oi ObjectInfo, e error) {
+	cacheObjPath := c.getCacheSHADir(bucket, object)
+	oi, e = c.statCache(ctx, cacheObjPath)
+	if e != nil {
+		return
+	}
+	oi.Bucket = bucket
+	oi.Name = object
+	return
+}
+
+// statCache is a convenience function for purge() to get ObjectInfo for cached object
+func (c *diskCache) statCache(ctx context.Context, cacheObjPath string) (oi ObjectInfo, e error) {
+	// Stat the file to get file size.
+	fi, err := fsStatFile(ctx, pathJoin(cacheObjPath, cacheDataFile))
+	if err != nil {
+		return oi, err
+	}
+	metaPath := pathJoin(cacheObjPath, cacheMetaJSONFile)
+
+	f, err := os.Open(metaPath)
+	if err != nil {
+		return oi, err
+	}
+	defer f.Close()
+	meta := &cacheMeta{}
+	if err := jsonLoad(f, meta); err != nil {
+		return oi, err
+	}
+	return meta.ToObjectInfo("", "", fi), nil
+}
+
+// caches object metadata to disk cache
+func (c *diskCache) saveMetadata(ctx context.Context, bucket, object string, meta map[string]string) error {
+	fileName := c.getCacheSHADir(bucket, object)
+	metaPath := pathJoin(fileName, cacheMetaJSONFile)
+
+	f, err := os.Create(metaPath)
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+	m := cacheMeta{Meta: meta}
+	jsonData, err := json.Marshal(m)
+	if err != nil {
+		return err
+	}
+	f.Write(jsonData)
+	return nil
+}
+
+func (c *diskCache) getCacheSHADir(bucket, object string) string {
+	return path.Join(c.dir, getSHA256Hash([]byte(path.Join(bucket, object))))
+}
+
+// Caches the object to disk
+func (c *diskCache) Put(ctx context.Context, bucket, object string, data io.Reader, size int64, opts ObjectOptions) error {
+	if c.diskUsageHigh() {
+		select {
+		case c.purgeChan <- struct{}{}:
+		default:
+		}
+		return errDiskFull
+	}
+	if !c.diskAvailable(size) {
+		return errDiskFull
+	}
+	cachePath := c.getCacheSHADir(bucket, object)
+	cLock := c.nsMutex.NewNSLock(cachePath, "")
+	if err := cLock.GetLock(globalObjectTimeout); err != nil {
+		return err
+	}
+	defer cLock.Unlock()
+	if err := os.MkdirAll(cachePath, 0777); err != nil {
+		return err
+	}
+	bufSize := int64(readSizeV1)
+	if size > 0 && bufSize > size {
+		bufSize = size
+	}
+	filePath := path.Join(cachePath, cacheDataFile)
+	buf := make([]byte, int(bufSize))
+	_, err := fsCreateFile(ctx, filePath, data, buf, size)
+	if IsErr(err, baseErrs...) {
+		c.setOnline(false)
+	}
+	if err != nil {
+		return err
+	}
+	return c.saveMetadata(ctx, bucket, object, opts.UserDefined)
+}
+
+// Get returns ObjectInfo and reader for object from disk cache
+func (c *diskCache) Get(ctx context.Context, bucket, object string, rs *HTTPRangeSpec, h http.Header, opts ObjectOptions) (gr *GetObjectReader, err error) {
+	cachePath := c.getCacheSHADir(bucket, object)
+	fileName := path.Join(cachePath, cacheDataFile)
+
+	cLock := c.nsMutex.NewNSLock(cachePath, "")
+	if err := cLock.GetRLock(globalObjectTimeout); err != nil {
+		return nil, err
+	}
+
+	defer cLock.RUnlock()
+	var objInfo ObjectInfo
+
+	if objInfo, err = c.stat(ctx, bucket, object); err != nil {
+		return nil, toObjectErr(err, bucket, object)
+	}
+	var nsUnlocker = func() {}
+	// For a directory, we need to send an reader that returns no bytes.
+	if hasSuffix(object, slashSeparator) {
+		// The lock taken above is released when
+		// objReader.Close() is called by the caller.
+		return NewGetObjectReaderFromReader(bytes.NewBuffer(nil), objInfo, opts.CheckCopyPrecondFn, nsUnlocker)
+	}
+	objReaderFn, off, length, rErr := NewGetObjectReader(rs, objInfo, opts.CheckCopyPrecondFn, nsUnlocker)
+	if rErr != nil {
+		return nil, rErr
+	}
+
+	// Read the object, doesn't exist returns an s3 compatible error.
+	readCloser, size, err := fsOpenFile(ctx, fileName, off)
+	if err != nil {
+		return nil, toObjectErr(err, bucket, object)
+	}
+	reader := io.LimitReader(readCloser, length)
+	closeFn := func() {
+		readCloser.Close()
+	}
+
+	// Check if range is valid
+	if off > size || off+length > size {
+		err = InvalidRange{off, length, size}
+		logger.LogIf(ctx, err)
+		closeFn()
+		nsUnlocker()
+		return nil, err
+	}
+
+	return objReaderFn(reader, h, opts.CheckCopyPrecondFn, closeFn)
+}
+
+// Deletes the cached object
+func (c *diskCache) Delete(ctx context.Context, bucket, object string) (err error) {
+	cachePath := c.getCacheSHADir(bucket, object)
+	cLock := c.nsMutex.NewNSLock(cachePath, "")
+	if err := cLock.GetLock(globalObjectTimeout); err != nil {
+		return err
+	}
+	defer cLock.Unlock()
+	return os.RemoveAll(cachePath)
+
+}
+
+// convenience function to check if object is cached on this diskCache
+func (c *diskCache) Exists(ctx context.Context, bucket, object string) bool {
+	fileName := getSHA256Hash([]byte(path.Join(bucket, object)))
+	if _, err := os.Stat(path.Join(c.dir, fileName)); err != nil {
+		return false
+	}
+	return true
+}
--- a/cmd/disk-cache-fs.go
+++ b/cmd/disk-cache-fs.go
@ -1,537 +0,0 @@
-/*
- * MinIO Cloud Storage, (C) 2018 MinIO, Inc.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package cmd
-
-import (
-	"context"
-	"encoding/json"
-	"fmt"
-	"io"
-	"io/ioutil"
-	"os"
-	"path"
-	"sync"
-	"time"
-
-	"github.com/minio/minio/cmd/logger"
-	"github.com/minio/minio/pkg/disk"
-	"github.com/minio/minio/pkg/lock"
-)
-
-const (
-	// cache.json object metadata for cached objects.
-	cacheMetaJSONFile = "cache.json"
-
-	cacheEnvDelimiter = ";"
-)
-
-// cacheFSObjects implements the cache backend operations.
-type cacheFSObjects struct {
-	*FSObjects
-	// caching drive path (from cache "drives" in config.json)
-	dir string
-	// expiry in days specified in config.json
-	expiry int
-	// max disk usage pct
-	maxDiskUsagePct int
-	// purge() listens on this channel to start the cache-purge process
-	purgeChan chan struct{}
-	// mark false if drive is offline
-	online bool
-	// mutex to protect updates to online variable
-	onlineMutex *sync.RWMutex
-}
-
-// Inits the cache directory if it is not init'ed already.
-// Initializing implies creation of new FS Object layer.
-func newCacheFSObjects(dir string, expiry int, maxDiskUsagePct int) (*cacheFSObjects, error) {
-	// Assign a new UUID for FS minio mode. Each server instance
-	// gets its own UUID for temporary file transaction.
-	fsUUID := mustGetUUID()
-
-	// Initialize meta volume, if volume already exists ignores it.
-	if err := initMetaVolumeFS(dir, fsUUID); err != nil {
-		return nil, fmt.Errorf("Unable to initialize '.minio.sys' meta volume, %s", err)
-	}
-
-	trashPath := pathJoin(dir, minioMetaBucket, cacheTrashDir)
-	if err := os.MkdirAll(trashPath, 0777); err != nil {
-		return nil, err
-	}
-
-	if expiry == 0 {
-		expiry = globalCacheExpiry
-	}
-
-	// Initialize fs objects.
-	fsObjects := &FSObjects{
-		fsPath:       dir,
-		metaJSONFile: cacheMetaJSONFile,
-		fsUUID:       fsUUID,
-		rwPool: &fsIOPool{
-			readersMap: make(map[string]*lock.RLockedFile),
-		},
-		nsMutex:       newNSLock(false),
-		listPool:      NewTreeWalkPool(globalLookupTimeout),
-		appendFileMap: make(map[string]*fsAppendFile),
-	}
-
-	go fsObjects.cleanupStaleMultipartUploads(context.Background(), GlobalMultipartCleanupInterval, GlobalMultipartExpiry, GlobalServiceDoneCh)
-
-	cacheFS := cacheFSObjects{
-		FSObjects:       fsObjects,
-		dir:             dir,
-		expiry:          expiry,
-		maxDiskUsagePct: maxDiskUsagePct,
-		purgeChan:       make(chan struct{}),
-		online:          true,
-		onlineMutex:     &sync.RWMutex{},
-	}
-	return &cacheFS, nil
-}
-
-// Returns if the disk usage is low.
-// Disk usage is low if usage is < 80% of cacheMaxDiskUsagePct
-// Ex. for a 100GB disk, if maxUsage is configured as 70% then cacheMaxDiskUsagePct is 70G
-// hence disk usage is low if the disk usage is less than 56G (because 80% of 70G is 56G)
-func (cfs *cacheFSObjects) diskUsageLow() bool {
-
-	minUsage := cfs.maxDiskUsagePct * 80 / 100
-	di, err := disk.GetInfo(cfs.dir)
-	if err != nil {
-		reqInfo := (&logger.ReqInfo{}).AppendTags("cachePath", cfs.dir)
-		ctx := logger.SetReqInfo(context.Background(), reqInfo)
-		logger.LogIf(ctx, err)
-		return false
-	}
-	usedPercent := (di.Total - di.Free) * 100 / di.Total
-	return int(usedPercent) < minUsage
-}
-
-// Return if the disk usage is high.
-// Disk usage is high if disk used is > cacheMaxDiskUsagePct
-func (cfs *cacheFSObjects) diskUsageHigh() bool {
-	di, err := disk.GetInfo(cfs.dir)
-	if err != nil {
-		reqInfo := (&logger.ReqInfo{}).AppendTags("cachePath", cfs.dir)
-		ctx := logger.SetReqInfo(context.Background(), reqInfo)
-		logger.LogIf(ctx, err)
-		return true
-	}
-	usedPercent := (di.Total - di.Free) * 100 / di.Total
-	return int(usedPercent) > cfs.maxDiskUsagePct
-}
-
-// Returns if size space can be allocated without exceeding
-// max disk usable for caching
-func (cfs *cacheFSObjects) diskAvailable(size int64) bool {
-	di, err := disk.GetInfo(cfs.dir)
-	if err != nil {
-		reqInfo := (&logger.ReqInfo{}).AppendTags("cachePath", cfs.dir)
-		ctx := logger.SetReqInfo(context.Background(), reqInfo)
-		logger.LogIf(ctx, err)
-		return false
-	}
-	usedPercent := (di.Total - (di.Free - uint64(size))) * 100 / di.Total
-	return int(usedPercent) < cfs.maxDiskUsagePct
-}
-
-// purges all content marked trash from the cache.
-func (cfs *cacheFSObjects) purgeTrash() {
-	ticker := time.NewTicker(time.Minute * cacheCleanupInterval)
-	defer ticker.Stop()
-
-	for {
-		select {
-		case <-GlobalServiceDoneCh:
-			return
-		case <-ticker.C:
-			trashPath := path.Join(cfs.fsPath, minioMetaBucket, cacheTrashDir)
-			entries, err := readDir(trashPath)
-			if err != nil {
-				return
-			}
-			for _, entry := range entries {
-				ctx := logger.SetReqInfo(context.Background(), &logger.ReqInfo{})
-				fi, err := fsStatVolume(ctx, pathJoin(trashPath, entry))
-				if err != nil {
-					continue
-				}
-				dir := path.Join(trashPath, fi.Name())
-
-				// Delete all expired cache content.
-				fsRemoveAll(ctx, dir)
-			}
-		}
-	}
-}
-
-// Purge cache entries that were not accessed.
-func (cfs *cacheFSObjects) purge() {
-	delimiter := slashSeparator
-	maxKeys := 1000
-	ctx := context.Background()
-	for {
-		olderThan := cfs.expiry
-		for !cfs.diskUsageLow() {
-			// delete unaccessed objects older than expiry duration
-			expiry := UTCNow().AddDate(0, 0, -1*olderThan)
-			olderThan /= 2
-			if olderThan < 1 {
-				break
-			}
-			deletedCount := 0
-			buckets, err := cfs.ListBuckets(ctx)
-			if err != nil {
-				logger.LogIf(ctx, err)
-			}
-			// Reset cache online status if drive was offline earlier.
-			if !cfs.IsOnline() {
-				cfs.setOnline(true)
-			}
-			for _, bucket := range buckets {
-				var continuationToken string
-				var marker string
-				for {
-					objects, err := cfs.ListObjects(ctx, bucket.Name, marker, continuationToken, delimiter, maxKeys)
-					if err != nil {
-						break
-					}
-
-					if !objects.IsTruncated {
-						break
-					}
-					marker = objects.NextMarker
-					for _, object := range objects.Objects {
-						// purge objects that qualify because of cache-control directives or
-						// past cache expiry duration.
-						if !filterFromCache(object.UserDefined) ||
-							!isStaleCache(object) ||
-							object.AccTime.After(expiry) {
-							continue
-						}
-						if err = cfs.DeleteObject(ctx, bucket.Name, object.Name); err != nil {
-							logger.LogIf(ctx, err)
-							continue
-						}
-						deletedCount++
-					}
-				}
-			}
-			if deletedCount == 0 {
-				// to avoid a busy loop
-				time.Sleep(time.Minute * 30)
-			}
-		}
-		<-cfs.purgeChan
-	}
-}
-
-// sets cache drive status
-func (cfs *cacheFSObjects) setOnline(status bool) {
-	cfs.onlineMutex.Lock()
-	cfs.online = status
-	cfs.onlineMutex.Unlock()
-}
-
-// returns true if cache drive is online
-func (cfs *cacheFSObjects) IsOnline() bool {
-	cfs.onlineMutex.RLock()
-	defer cfs.onlineMutex.RUnlock()
-	return cfs.online
-}
-
-// Caches the object to disk
-func (cfs *cacheFSObjects) Put(ctx context.Context, bucket, object string, data *PutObjReader, opts ObjectOptions) error {
-	if cfs.diskUsageHigh() {
-		select {
-		case cfs.purgeChan <- struct{}{}:
-		default:
-		}
-		return errDiskFull
-	}
-	if !cfs.diskAvailable(data.Size()) {
-		return errDiskFull
-	}
-	if _, err := cfs.GetBucketInfo(ctx, bucket); err != nil {
-		pErr := cfs.MakeBucketWithLocation(ctx, bucket, "")
-		if pErr != nil {
-			return pErr
-		}
-	}
-	_, err := cfs.PutObject(ctx, bucket, object, data, opts)
-	// if err is due to disk being offline , mark cache drive as offline
-	if IsErr(err, baseErrs...) {
-		cfs.setOnline(false)
-	}
-	return err
-}
-
-// Returns the handle for the cached object
-func (cfs *cacheFSObjects) Get(ctx context.Context, bucket, object string, startOffset int64, length int64, writer io.Writer, etag string, opts ObjectOptions) (err error) {
-	return cfs.GetObject(ctx, bucket, object, startOffset, length, writer, etag, opts)
-}
-
-// Deletes the cached object
-func (cfs *cacheFSObjects) Delete(ctx context.Context, bucket, object string) (err error) {
-	return cfs.DeleteObject(ctx, bucket, object)
-}
-
-// convenience function to check if object is cached on this cacheFSObjects
-func (cfs *cacheFSObjects) Exists(ctx context.Context, bucket, object string) bool {
-	_, err := cfs.GetObjectInfo(ctx, bucket, object, ObjectOptions{})
-	return err == nil
-}
-
-// Identical to fs PutObject operation except that it uses ETag in metadata
-// headers.
-func (cfs *cacheFSObjects) PutObject(ctx context.Context, bucket string, object string, r *PutObjReader, opts ObjectOptions) (objInfo ObjectInfo, retErr error) {
-	data := r.Reader
-	fs := cfs.FSObjects
-	// Lock the object.
-	objectLock := fs.nsMutex.NewNSLock(bucket, object)
-	if err := objectLock.GetLock(globalObjectTimeout); err != nil {
-		return objInfo, err
-	}
-	defer objectLock.Unlock()
-
-	// No metadata is set, allocate a new one.
-	meta := make(map[string]string)
-	for k, v := range opts.UserDefined {
-		meta[k] = v
-	}
-
-	var err error
-
-	// Validate if bucket name is valid and exists.
-	if _, err = fs.statBucketDir(ctx, bucket); err != nil {
-		return ObjectInfo{}, toObjectErr(err, bucket)
-	}
-
-	fsMeta := newFSMetaV1()
-	fsMeta.Meta = meta
-
-	// This is a special case with size as '0' and object ends
-	// with a slash separator, we treat it like a valid operation
-	// and return success.
-	if isObjectDir(object, data.Size()) {
-		// Check if an object is present as one of the parent dir.
-		if fs.parentDirIsObject(ctx, bucket, path.Dir(object)) {
-			return ObjectInfo{}, toObjectErr(errFileParentIsFile, bucket, object)
-		}
-		if err = mkdirAll(pathJoin(fs.fsPath, bucket, object), 0777); err != nil {
-			return ObjectInfo{}, toObjectErr(err, bucket, object)
-		}
-		var fi os.FileInfo
-		if fi, err = fsStatDir(ctx, pathJoin(fs.fsPath, bucket, object)); err != nil {
-			return ObjectInfo{}, toObjectErr(err, bucket, object)
-		}
-		return fsMeta.ToObjectInfo(bucket, object, fi), nil
-	}
-
-	if err = checkPutObjectArgs(ctx, bucket, object, fs, data.Size()); err != nil {
-		return ObjectInfo{}, err
-	}
-
-	// Check if an object is present as one of the parent dir.
-	if fs.parentDirIsObject(ctx, bucket, path.Dir(object)) {
-		return ObjectInfo{}, toObjectErr(errFileParentIsFile, bucket, object)
-	}
-
-	// Validate input data size and it can never be less than zero.
-	if data.Size() < -1 {
-		logger.LogIf(ctx, errInvalidArgument)
-		return ObjectInfo{}, errInvalidArgument
-	}
-
-	var wlk *lock.LockedFile
-	if bucket != minioMetaBucket {
-		bucketMetaDir := pathJoin(fs.fsPath, minioMetaBucket, bucketMetaPrefix)
-		fsMetaPath := pathJoin(bucketMetaDir, bucket, object, fs.metaJSONFile)
-
-		wlk, err = fs.rwPool.Create(fsMetaPath)
-		if err != nil {
-			logger.LogIf(ctx, err)
-			return ObjectInfo{}, toObjectErr(err, bucket, object)
-		}
-		// This close will allow for locks to be synchronized on `fs.json`.
-		defer wlk.Close()
-		defer func() {
-			// Remove meta file when PutObject encounters any error
-			if retErr != nil {
-				tmpDir := pathJoin(fs.fsPath, minioMetaTmpBucket, fs.fsUUID)
-				fsRemoveMeta(ctx, bucketMetaDir, fsMetaPath, tmpDir)
-			}
-		}()
-	}
-
-	// Uploaded object will first be written to the temporary location which will eventually
-	// be renamed to the actual location. It is first written to the temporary location
-	// so that cleaning it up will be easy if the server goes down.
-	tempObj := mustGetUUID()
-
-	// Allocate a buffer to Read() from request body
-	bufSize := int64(readSizeV1)
-	if size := data.Size(); size > 0 && bufSize > size {
-		bufSize = size
-	}
-
-	buf := make([]byte, int(bufSize))
-	fsTmpObjPath := pathJoin(fs.fsPath, minioMetaTmpBucket, fs.fsUUID, tempObj)
-	bytesWritten, err := fsCreateFile(ctx, fsTmpObjPath, data, buf, data.Size())
-	if err != nil {
-		fsRemoveFile(ctx, fsTmpObjPath)
-		return ObjectInfo{}, toObjectErr(err, bucket, object)
-	}
-	if fsMeta.Meta["etag"] == "" {
-		fsMeta.Meta["etag"] = r.MD5CurrentHexString()
-	}
-	// Should return IncompleteBody{} error when reader has fewer
-	// bytes than specified in request header.
-	if bytesWritten < data.Size() {
-		fsRemoveFile(ctx, fsTmpObjPath)
-		return ObjectInfo{}, IncompleteBody{}
-	}
-
-	// Delete the temporary object in the case of a
-	// failure. If PutObject succeeds, then there would be
-	// nothing to delete.
-	defer fsRemoveFile(ctx, fsTmpObjPath)
-
-	// Entire object was written to the temp location, now it's safe to rename it to the actual location.
-	fsNSObjPath := pathJoin(fs.fsPath, bucket, object)
-	if err = fsRenameFile(ctx, fsTmpObjPath, fsNSObjPath); err != nil {
-		return ObjectInfo{}, toObjectErr(err, bucket, object)
-	}
-
-	if bucket != minioMetaBucket {
-		// Write FS metadata after a successful namespace operation.
-		if _, err = fsMeta.WriteTo(wlk); err != nil {
-			return ObjectInfo{}, toObjectErr(err, bucket, object)
-		}
-	}
-
-	// Stat the file to fetch timestamp, size.
-	fi, err := fsStatFile(ctx, pathJoin(fs.fsPath, bucket, object))
-	if err != nil {
-		return ObjectInfo{}, toObjectErr(err, bucket, object)
-	}
-	// Success.
-	return fsMeta.ToObjectInfo(bucket, object, fi), nil
-}
-
-// Implements S3 compatible initiate multipart API. Operation here is identical
-// to fs backend implementation - with the exception that cache FS uses the uploadID
-// generated on the backend
-func (cfs *cacheFSObjects) NewMultipartUpload(ctx context.Context, bucket, object string, uploadID string, opts ObjectOptions) (string, error) {
-	if cfs.diskUsageHigh() {
-		select {
-		case cfs.purgeChan <- struct{}{}:
-		default:
-		}
-		return "", errDiskFull
-	}
-
-	if _, err := cfs.GetBucketInfo(ctx, bucket); err != nil {
-		pErr := cfs.MakeBucketWithLocation(ctx, bucket, "")
-		if pErr != nil {
-			return "", pErr
-		}
-	}
-	fs := cfs.FSObjects
-	if err := checkNewMultipartArgs(ctx, bucket, object, fs); err != nil {
-		return "", toObjectErr(err, bucket)
-	}
-
-	if _, err := fs.statBucketDir(ctx, bucket); err != nil {
-		return "", toObjectErr(err, bucket)
-	}
-
-	uploadIDDir := fs.getUploadIDDir(bucket, object, uploadID)
-
-	err := mkdirAll(uploadIDDir, 0755)
-	if err != nil {
-		logger.LogIf(ctx, err)
-		return "", err
-	}
-
-	// Initialize fs.json values.
-	fsMeta := newFSMetaV1()
-	fsMeta.Meta = opts.UserDefined
-
-	fsMetaBytes, err := json.Marshal(fsMeta)
-	if err != nil {
-		logger.LogIf(ctx, err)
-		return "", err
-	}
-
-	if err = ioutil.WriteFile(pathJoin(uploadIDDir, fs.metaJSONFile), fsMetaBytes, 0644); err != nil {
-		logger.LogIf(ctx, err)
-		return "", err
-	}
-	return uploadID, nil
-}
-
-// moveBucketToTrash clears cacheFSObjects of bucket contents and moves it to trash folder.
-func (cfs *cacheFSObjects) moveBucketToTrash(ctx context.Context, bucket string) (err error) {
-	fs := cfs.FSObjects
-	bucketLock := fs.nsMutex.NewNSLock(bucket, "")
-	if err = bucketLock.GetLock(globalObjectTimeout); err != nil {
-		return err
-	}
-	defer bucketLock.Unlock()
-	bucketDir, err := fs.getBucketDir(ctx, bucket)
-	if err != nil {
-		return toObjectErr(err, bucket)
-	}
-	trashPath := pathJoin(cfs.fsPath, minioMetaBucket, cacheTrashDir)
-	expiredDir := path.Join(trashPath, bucket)
-	// Attempt to move regular bucket to expired directory.
-	if err = fsRenameDir(bucketDir, expiredDir); err != nil {
-		logger.LogIf(ctx, err)
-		return toObjectErr(err, bucket)
-	}
-	// Cleanup all the bucket metadata.
-	ominioMetadataBucketDir := pathJoin(fs.fsPath, minioMetaBucket, bucketMetaPrefix, bucket)
-	nminioMetadataBucketDir := pathJoin(trashPath, MustGetUUID())
-	logger.LogIf(ctx, fsRenameDir(ominioMetadataBucketDir, nminioMetadataBucketDir))
-	return nil
-}
-
-// Removes a directory only if its empty, handles long
-// paths for windows automatically.
-func fsRenameDir(dirPath, newPath string) (err error) {
-	if dirPath == "" || newPath == "" {
-		return errInvalidArgument
-	}
-
-	if err = checkPathLength(dirPath); err != nil {
-		return err
-	}
-	if err = checkPathLength(newPath); err != nil {
-		return err
-	}
-	if err = os.Rename(dirPath, newPath); err != nil {
-		if os.IsNotExist(err) {
-			return errVolumeNotFound
-		} else if isSysErrNotEmpty(err) {
-			return errVolumeNotEmpty
-		}
-		return err
-	}
-	return nil
-}
--- a/cmd/disk-cache-utils.go
+++ b/cmd/disk-cache-utils.go
@ -0,0 +1,146 @@
+/*
+ * MinIO Cloud Storage, (C) 2019 MinIO, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package cmd
+
+import (
+	"net/http"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/minio/minio/cmd/crypto"
+)
+
+type cacheControl struct {
+	exclude  bool
+	expiry   time.Time
+	maxAge   int
+	sMaxAge  int
+	minFresh int
+}
+
+// cache exclude directives in cache-control header
+var cacheExcludeDirectives = []string{
+	"no-cache",
+	"no-store",
+	"must-revalidate",
+}
+
+// returns true if cache exclude directives are set.
+func isCacheExcludeDirective(s string) bool {
+	for _, directive := range cacheExcludeDirectives {
+		if s == directive {
+			return true
+		}
+	}
+	return false
+}
+
+// returns struct with cache-control settings from user metadata.
+func getCacheControlOpts(m map[string]string) (c cacheControl, err error) {
+	var headerVal string
+	for k, v := range m {
+		if k == "cache-control" {
+			headerVal = v
+		}
+		if k == "expires" {
+			if e, err := http.ParseTime(v); err == nil {
+				c.expiry = e
+			}
+		}
+	}
+	if headerVal == "" {
+		return
+	}
+	headerVal = strings.ToLower(headerVal)
+	headerVal = strings.TrimSpace(headerVal)
+
+	vals := strings.Split(headerVal, ",")
+	for _, val := range vals {
+		val = strings.TrimSpace(val)
+		p := strings.Split(val, "=")
+		if isCacheExcludeDirective(p[0]) {
+			c.exclude = true
+			continue
+		}
+
+		if len(p) != 2 {
+			continue
+		}
+		if p[0] == "max-age" ||
+			p[0] == "s-maxage" ||
+			p[0] == "min-fresh" {
+			i, err := strconv.Atoi(p[1])
+			if err != nil {
+				return c, err
+			}
+			if p[0] == "max-age" {
+				c.maxAge = i
+			}
+			if p[0] == "s-maxage" {
+				c.sMaxAge = i
+			}
+			if p[0] == "min-fresh" {
+				c.minFresh = i
+			}
+		}
+	}
+	return c, nil
+}
+
+// return true if metadata has a cache-control header
+// directive to exclude object from cache.
+func filterFromCache(m map[string]string) bool {
+	c, err := getCacheControlOpts(m)
+	if err != nil {
+		return false
+	}
+	return c.exclude
+}
+
+// returns true if cache expiry conditions met in cache-control/expiry metadata.
+func isStaleCache(objInfo ObjectInfo) bool {
+	c, err := getCacheControlOpts(objInfo.UserDefined)
+	if err != nil {
+		return false
+	}
+	now := time.Now()
+	if c.sMaxAge > 0 && c.sMaxAge > int(now.Sub(objInfo.ModTime).Seconds()) {
+		return true
+	}
+	if c.maxAge > 0 && c.maxAge > int(now.Sub(objInfo.ModTime).Seconds()) {
+		return true
+	}
+	if !c.expiry.Equal(time.Time{}) && c.expiry.Before(time.Now()) {
+		return true
+	}
+	if c.minFresh > 0 && c.minFresh <= int(now.Sub(objInfo.ModTime).Seconds()) {
+		return true
+	}
+	return false
+}
+
+// backendDownError returns true if err is due to backend failure or faulty disk if in server mode
+func backendDownError(err error) bool {
+	_, backendDown := err.(BackendDown)
+	return backendDown || IsErr(err, baseErrs...)
+}
+
+// IsCacheable returns if the object should be saved in the cache.
+func (o ObjectInfo) IsCacheable() bool {
+	return !crypto.IsEncrypted(o.UserDefined)
+}
--- a/cmd/disk-cache.go
+++ b/cmd/disk-cache.go
--- a/cmd/disk-cache_test.go
+++ b/cmd/disk-cache_test.go
@ -1,5 +1,5 @@
 /*
- * MinIO Cloud Storage, (C) 2018 MinIO, Inc.
+ * MinIO Cloud Storage, (C) 2018,2019 MinIO, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
@ -19,6 +19,8 @@ package cmd
 import (
 	"bytes"
 	"context"
+	"io"
+	"net/http"
 	"reflect"
 	"testing"
 	"time"
@ -26,27 +28,45 @@ import (
 	"github.com/minio/minio/pkg/hash"
 )

-// Initialize cache FS objects.
-func initCacheFSObjects(disk string, cacheMaxUse int) (*cacheFSObjects, error) {
-	return newCacheFSObjects(disk, globalCacheExpiry, cacheMaxUse)
+// Initialize cache objects.
+func initCacheObjects(disk string, cacheMaxUse int) (*diskCache, error) {
+	return newdiskCache(disk, globalCacheExpiry, cacheMaxUse)
 }

 // inits diskCache struct for nDisks
-func initDiskCaches(drives []string, cacheMaxUse int, t *testing.T) (*diskCache, error) {
-	var cfs []*cacheFSObjects
+func initDiskCaches(drives []string, cacheMaxUse int, t *testing.T) ([]*diskCache, error) {
+	var cb []*diskCache
 	for _, d := range drives {
-		obj, err := initCacheFSObjects(d, cacheMaxUse)
+		obj, err := initCacheObjects(d, cacheMaxUse)
 		if err != nil {
 			return nil, err
 		}
-		cfs = append(cfs, obj)
+		cb = append(cb, obj)
+	}
+	return cb, nil
+}
+
+// Tests ToObjectInfo function.
+func TestCacheMetadataObjInfo(t *testing.T) {
+	m := cacheMeta{Meta: nil}
+	objInfo := m.ToObjectInfo("testbucket", "testobject", nil)
+	if objInfo.Size != 0 {
+		t.Fatal("Unexpected object info value for Size", objInfo.Size)
+	}
+	if objInfo.ModTime != timeSentinel {
+		t.Fatal("Unexpected object info value for ModTime ", objInfo.ModTime)
+	}
+	if objInfo.IsDir {
+		t.Fatal("Unexpected object info value for IsDir", objInfo.IsDir)
+	}
+	if !objInfo.Expires.IsZero() {
+		t.Fatal("Unexpected object info value for Expires ", objInfo.Expires)
 	}
-	return &diskCache{cfs: cfs}, nil
 }

 // test whether a drive being offline causes
-// getCacheFS to fetch next online drive
-func TestGetCacheFS(t *testing.T) {
+// getCachedLoc to fetch next online drive
+func TestGetCachedLoc(t *testing.T) {
 	for n := 1; n < 10; n++ {
 		fsDirs, err := getRandomDisks(n)
 		if err != nil {
@ -56,14 +76,15 @@ func TestGetCacheFS(t *testing.T) {
 		if err != nil {
 			t.Fatal(err)
 		}
+		c := cacheObjects{cache: d}
 		bucketName := "testbucket"
 		objectName := "testobject"
 		ctx := context.Background()
 		// find cache drive where object would be hashed
-		index := d.hashIndex(bucketName, objectName)
+		index := c.hashIndex(bucketName, objectName)
 		// turn off drive by setting online status to false
-		d.cfs[index].online = false
-		cfs, err := d.getCacheFS(ctx, bucketName, objectName)
+		c.cache[index].online = false
+		cfs, err := c.getCachedLoc(ctx, bucketName, objectName)
 		if n == 1 && err == errDiskNotFound {
 			continue
 		}
@ -71,7 +92,7 @@ func TestGetCacheFS(t *testing.T) {
 			t.Fatal(err)
 		}
 		i := -1
-		for j, f := range d.cfs {
+		for j, f := range c.cache {
 			if f == cfs {
 				i = j
 				break
@ -84,8 +105,8 @@ func TestGetCacheFS(t *testing.T) {
 }

 // test whether a drive being offline causes
-// getCacheFS to fetch next online drive
-func TestGetCacheFSMaxUse(t *testing.T) {
+// getCachedLoc to fetch next online drive
+func TestGetCacheMaxUse(t *testing.T) {
 	for n := 1; n < 10; n++ {
 		fsDirs, err := getRandomDisks(n)
 		if err != nil {
@ -95,14 +116,16 @@ func TestGetCacheFSMaxUse(t *testing.T) {
 		if err != nil {
 			t.Fatal(err)
 		}
+		c := cacheObjects{cache: d}
+
 		bucketName := "testbucket"
 		objectName := "testobject"
 		ctx := context.Background()
 		// find cache drive where object would be hashed
-		index := d.hashIndex(bucketName, objectName)
+		index := c.hashIndex(bucketName, objectName)
 		// turn off drive by setting online status to false
-		d.cfs[index].online = false
-		cfs, err := d.getCacheFS(ctx, bucketName, objectName)
+		c.cache[index].online = false
+		cb, err := c.getCachedLoc(ctx, bucketName, objectName)
 		if n == 1 && err == errDiskNotFound {
 			continue
 		}
@ -110,8 +133,8 @@ func TestGetCacheFSMaxUse(t *testing.T) {
 			t.Fatal(err)
 		}
 		i := -1
-		for j, f := range d.cfs {
-			if f == cfs {
+		for j, f := range d {
+			if f == cb {
 				i = j
 				break
 			}
@ -172,7 +195,9 @@ func TestDiskCache(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	cache := d.cfs[0]
+	c := cacheObjects{cache: d}
+
+	cache := c.cache[0]
 	ctx := context.Background()
 	bucketName := "testbucket"
 	objectName := "testobject"
@ -198,14 +223,17 @@ func TestDiskCache(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	err = cache.Put(ctx, bucketName, objectName, NewPutObjReader(hashReader, nil, nil), ObjectOptions{UserDefined: httpMeta})
+	err = cache.Put(ctx, bucketName, objectName, hashReader, hashReader.Size(), ObjectOptions{UserDefined: httpMeta})
 	if err != nil {
 		t.Fatal(err)
 	}
-	cachedObjInfo, err := cache.GetObjectInfo(ctx, bucketName, objectName, opts)
+	cReader, err := cache.Get(ctx, bucketName, objectName, nil, http.Header{
+		"Content-Type": []string{"application/json"},
+	}, opts)
 	if err != nil {
 		t.Fatal(err)
 	}
+	cachedObjInfo := cReader.ObjInfo
 	if !cache.Exists(ctx, bucketName, objectName) {
 		t.Fatal("Expected object to exist on cache")
 	}
@ -219,7 +247,7 @@ func TestDiskCache(t *testing.T) {
 		t.Fatal("Cached content-type does not match")
 	}
 	writer := bytes.NewBuffer(nil)
-	err = cache.Get(ctx, bucketName, objectName, 0, int64(size), writer, "", opts)
+	_, err = io.Copy(writer, cReader)
 	if err != nil {
 		t.Fatal(err)
 	}
@ -246,7 +274,7 @@ func TestDiskCacheMaxUse(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	cache := d.cfs[0]
+	cache := d[0]
 	ctx := context.Background()
 	bucketName := "testbucket"
 	objectName := "testobject"
@ -274,19 +302,20 @@ func TestDiskCacheMaxUse(t *testing.T) {
 		t.Fatal(err)
 	}
 	if !cache.diskAvailable(int64(size)) {
-		err = cache.Put(ctx, bucketName, objectName, NewPutObjReader(hashReader, nil, nil), ObjectOptions{UserDefined: httpMeta})
+		err = cache.Put(ctx, bucketName, objectName, hashReader, hashReader.Size(), ObjectOptions{UserDefined: httpMeta})
 		if err != errDiskFull {
 			t.Fatal("Cache max-use limit violated.")
 		}
 	} else {
-		err = cache.Put(ctx, bucketName, objectName, NewPutObjReader(hashReader, nil, nil), ObjectOptions{UserDefined: httpMeta})
+		err = cache.Put(ctx, bucketName, objectName, hashReader, hashReader.Size(), ObjectOptions{UserDefined: httpMeta})
 		if err != nil {
 			t.Fatal(err)
 		}
-		cachedObjInfo, err := cache.GetObjectInfo(ctx, bucketName, objectName, opts)
+		cReader, err := cache.Get(ctx, bucketName, objectName, nil, nil, opts)
 		if err != nil {
 			t.Fatal(err)
 		}
+		cachedObjInfo := cReader.ObjInfo
 		if !cache.Exists(ctx, bucketName, objectName) {
 			t.Fatal("Expected object to exist on cache")
 		}
@ -300,7 +329,7 @@ func TestDiskCacheMaxUse(t *testing.T) {
 			t.Fatal("Cached content-type does not match")
 		}
 		writer := bytes.NewBuffer(nil)
-		err = cache.Get(ctx, bucketName, objectName, 0, int64(size), writer, "", opts)
+		_, err = io.Copy(writer, cReader)
 		if err != nil {
 			t.Fatal(err)
 		}
--- a/cmd/object-handlers.go
+++ b/cmd/object-handlers.go
@ -1249,10 +1249,6 @@ func (api objectAPIHandlers) PutObjectHandler(w http.ResponseWriter, r *http.Req
 	// Ensure that metadata does not contain sensitive information
 	crypto.RemoveSensitiveEntries(metadata)

-	if api.CacheAPI() != nil && !hasServerSideEncryptionHeader(r.Header) {
-		putObject = api.CacheAPI().PutObject
-	}
-
 	// Create the object..
 	objInfo, err := putObject(ctx, bucket, object, pReader, opts)
 	if err != nil {
@ -1404,9 +1400,7 @@ func (api objectAPIHandlers) NewMultipartUploadHandler(w http.ResponseWriter, r
 		return
 	}
 	newMultipartUpload := objectAPI.NewMultipartUpload
-	if api.CacheAPI() != nil && !hasServerSideEncryptionHeader(r.Header) {
-		newMultipartUpload = api.CacheAPI().NewMultipartUpload
-	}
+
 	uploadID, err := newMultipartUpload(ctx, bucket, object, opts)
 	if err != nil {
 		writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL, guessIsBrowserReq(r))
@ -1935,9 +1929,7 @@ func (api objectAPIHandlers) PutObjectPartHandler(w http.ResponseWriter, r *http
 	}

 	putObjectPart := objectAPI.PutObjectPart
-	if api.CacheAPI() != nil && !isEncrypted {
-		putObjectPart = api.CacheAPI().PutObjectPart
-	}
+
 	partInfo, err := putObjectPart(ctx, bucket, object, uploadID, partID, pReader, opts)
 	if err != nil {
 		// Verify if the underlying error is signature mismatch.
@ -1970,9 +1962,6 @@ func (api objectAPIHandlers) AbortMultipartUploadHandler(w http.ResponseWriter,
 		return
 	}
 	abortMultipartUpload := objectAPI.AbortMultipartUpload
-	if api.CacheAPI() != nil {
-		abortMultipartUpload = api.CacheAPI().AbortMultipartUpload
-	}

 	if s3Error := checkRequestAuthType(ctx, r, policy.AbortMultipartUploadAction, bucket, object); s3Error != ErrNone {
 		writeErrorResponse(ctx, w, errorCodes.ToAPIErr(s3Error), r.URL, guessIsBrowserReq(r))
@ -2253,9 +2242,6 @@ func (api objectAPIHandlers) CompleteMultipartUploadHandler(w http.ResponseWrite
 	}

 	completeMultiPartUpload := objectAPI.CompleteMultipartUpload
-	if api.CacheAPI() != nil {
-		completeMultiPartUpload = api.CacheAPI().CompleteMultipartUpload
-	}

 	// This code is specifically to handle the requirements for slow
 	// complete multipart upload operations on FS mode.
--- a/cmd/web-handlers.go
+++ b/cmd/web-handlers.go
@ -253,9 +253,6 @@ func (web *webAPIHandlers) DeleteBucket(r *http.Request, args *RemoveBucketArgs,
 	ctx := context.Background()

 	deleteBucket := objectAPI.DeleteBucket
-	if web.CacheAPI() != nil {
-		deleteBucket = web.CacheAPI().DeleteBucket
-	}

 	if err := deleteBucket(ctx, args.BucketName); err != nil {
 		return toJSONError(err, args.BucketName)
@ -297,9 +294,6 @@ func (web *webAPIHandlers) ListBuckets(r *http.Request, args *WebGenericArgs, re
 		return toJSONError(errServerNotInitialized)
 	}
 	listBuckets := objectAPI.ListBuckets
-	if web.CacheAPI() != nil {
-		listBuckets = web.CacheAPI().ListBuckets
-	}

 	claims, owner, authErr := webRequestAuthenticate(r)
 	if authErr != nil {
@ -403,9 +397,6 @@ func (web *webAPIHandlers) ListObjects(r *http.Request, args *ListObjectsArgs, r
 	}

 	listObjects := objectAPI.ListObjects
-	if web.CacheAPI() != nil {
-		listObjects = web.CacheAPI().ListObjects
-	}

 	if isRemoteCallRequired(context.Background(), args.BucketName, objectAPI) {
 		sr, err := globalDNSConfig.Get(args.BucketName)
@ -577,9 +568,6 @@ func (web *webAPIHandlers) RemoveObject(r *http.Request, args *RemoveObjectArgs,
 		return toJSONError(errServerNotInitialized)
 	}
 	listObjects := objectAPI.ListObjects
-	if web.CacheAPI() != nil {
-		listObjects = web.CacheAPI().ListObjects
-	}

 	claims, owner, authErr := webRequestAuthenticate(r)
 	if authErr != nil {
@ -1018,9 +1006,7 @@ func (web *webAPIHandlers) Upload(w http.ResponseWriter, r *http.Request) {
 	}

 	putObject := objectAPI.PutObject
-	if !hasServerSideEncryptionHeader(r.Header) && web.CacheAPI() != nil {
-		putObject = web.CacheAPI().PutObject
-	}
+
 	objInfo, err := putObject(context.Background(), bucket, object, pReader, opts)
 	if err != nil {
 		writeWebErrorResponse(w, err)
@ -1260,32 +1246,29 @@ func (web *webAPIHandlers) DownloadZip(w http.ResponseWriter, r *http.Request) {
 		writeWebErrorResponse(w, errInvalidBucketName)
 		return
 	}
+	getObjectNInfo := objectAPI.GetObjectNInfo
+	if web.CacheAPI() != nil {
+		getObjectNInfo = web.CacheAPI().GetObjectNInfo
+	}

-	getObject := objectAPI.GetObject
-	if web.CacheAPI() != nil {
-		getObject = web.CacheAPI().GetObject
-	}
 	listObjects := objectAPI.ListObjects
-	if web.CacheAPI() != nil {
-		listObjects = web.CacheAPI().ListObjects
-	}

 	archive := zip.NewWriter(w)
 	defer archive.Close()

-	getObjectInfo := objectAPI.GetObjectInfo
-	if web.CacheAPI() != nil {
-		getObjectInfo = web.CacheAPI().GetObjectInfo
-	}
-	opts := ObjectOptions{}
 	var length int64
 	for _, object := range args.Objects {
 		// Writes compressed object file to the response.
 		zipit := func(objectName string) error {
-			info, err := getObjectInfo(ctx, args.BucketName, objectName, opts)
+			var opts ObjectOptions
+			gr, err := getObjectNInfo(ctx, args.BucketName, objectName, nil, r.Header, readLock, opts)
 			if err != nil {
 				return err
 			}
+			defer gr.Close()
+
+			info := gr.ObjInfo
+
 			length = info.Size
 			if objectAPI.IsEncryptionSupported() {
 				if _, err = DecryptObjectInfo(&info, r.Header); err != nil {
@ -1348,7 +1331,7 @@ func (web *webAPIHandlers) DownloadZip(w http.ResponseWriter, r *http.Request) {
 				// Response writer should be limited early on for decryption upto required length,
 				// additionally also skipping mod(offset)64KiB boundaries.
 				writer = ioutil.LimitedWriter(writer, startOffset%(64*1024), length)
-				writer, startOffset, length, err = DecryptBlocksRequest(writer, r,
+				writer, _, length, err = DecryptBlocksRequest(writer, r,
 					args.BucketName, objectName, startOffset, length, info, false)
 				if err != nil {
 					writeWebErrorResponse(w, err)
@ -1356,14 +1339,20 @@ func (web *webAPIHandlers) DownloadZip(w http.ResponseWriter, r *http.Request) {
 				}
 			}
 			httpWriter := ioutil.WriteOnClose(writer)
-			if err = getObject(ctx, args.BucketName, objectName, startOffset, length, httpWriter, "", opts); err != nil {
+
+			// Write object content to response body
+			if _, err = io.Copy(httpWriter, gr); err != nil {
 				httpWriter.Close()
 				if info.IsCompressed() {
 					// Wait for decompression go-routine to retire.
 					wg.Wait()
 				}
+				if !httpWriter.HasWritten() { // write error response only if no data or headers has been written to client yet
+					writeWebErrorResponse(w, err)
+				}
 				return err
 			}
+
 			if err = httpWriter.Close(); err != nil {
 				if !httpWriter.HasWritten() { // write error response only if no data has been written to client yet
 					writeWebErrorResponse(w, err)
--- a/docs/disk-caching/DESIGN.md
+++ b/docs/disk-caching/DESIGN.md
@ -34,13 +34,12 @@ minio server -h
 - An object is only cached when drive has sufficient disk space.

 ## Behavior
-Disk caching caches objects for both **uploaded** and **downloaded** objects i.e
+Disk caching caches objects for **downloaded** objects i.e

 - Caches new objects for entries not found in cache while downloading. Otherwise serves from the cache.
- Caches all successfully uploaded objects. Replaces existing cached entry of the same object if needed.
 - When an object is deleted, corresponding entry in cache if any is deleted as well.
 - Cache continues to work for read-only operations such as GET, HEAD when backend is offline.
- Cache disallows write operations when backend is offline.
+- Cache-Control and Expires headers can be used to control how long objects stay in the cache

 > NOTE: Expiration happens automatically based on the configured interval as explained above, frequently accessed objects stay alive in cache for a significantly longer time.

@ -49,5 +48,6 @@ Upon restart of minio server after a running minio process is killed or crashes,

 ## Limits
 - Bucket policies are not cached, so anonymous operations are not supported when backend is offline.
+- To ensure security guarantees, encrypted objects are never cached.
 - Objects are distributed using deterministic hashing among the list of configured cache drives. If one or more drives go offline, or cache drive configuration is altered in any way, performance may degrade to a linear lookup time depending on the number of disks in cache.