feat: add directio option for scoutfs backend

backend/scoutfs/scoutfs.go

@@ -68,6 +68,9 @@ type ScoutfsOpts struct {
 	// (e.g. "CRC64NVME-<base64>"). For multipart uploads, part ETags become
 	// CRC64NVME-based values and the completed object ETag is checksum-derived.
 	DataIntegrityEtag bool
+	// EnableODirect enables best-effort O_DIRECT for object data reads/writes.
+	// Disabled by default.
+	EnableODirect bool
 	// ObjectLockMode selects local or none for conditional object publishes.
 	ObjectLockMode posix.ObjectLockMode
 }

backend/scoutfs/scoutfs_compat.go

@@ -84,6 +84,7 @@ func New(rootdir string, opts ScoutfsOpts) (*ScoutFS, error) {
 		CopyObjectThreshold: opts.CopyObjectThreshold,
 		DefaultEtag:         opts.DefaultEtag,
 		DataIntegrityEtag:   opts.DataIntegrityEtag,
+		EnableODirect:       opts.EnableODirect,
 		ObjectLockMode:      objectLockMode,
 	}
 	if opts.newDirPermSet {

cmd/internal/gwcli/scoutfs.go

@@ -138,6 +138,12 @@ move interfaces as well as support for tiered filesystems.`,
 				EnvVars:     []string{"VGW_DATA_INTEGRITY_ETAG"},
 				Destination: &dataIntegrityEtag,
 			},
+			&cli.BoolFlag{
+				Name:        "enable-odirect",
+				Usage:       "enable best-effort O_DIRECT for object data reads/writes",
+				EnvVars:     []string{"VGW_ENABLE_O_DIRECT"},
+				Destination: &enableODirect,
+			},
 		},
 	}
 }
@@ -177,6 +183,7 @@ func runScoutfs(ctx *cli.Context) error {
 	opts.ObjectLockMode = posix.ObjectLockMode(scoutfsLockMode)
 	opts.DefaultEtag = defaultEtag
 	opts.DataIntegrityEtag = dataIntegrityEtag
+	opts.EnableODirect = enableODirect
 	opts.SetNewDirPerm(fs.FileMode(dirPerms))
 	opts.SetNewFilePerm(fs.FileMode(filePerms))
 

extra/example.conf

@@ -727,12 +727,13 @@ ROOT_SECRET_ACCESS_KEY=
 #VGW_DISABLE_OBJECT_LOCK_FILE=false
 
 # The VGW_ENABLE_O_DIRECT option enables best-effort O_DIRECT for object data
-# reads and writes. This is disabled by default. When enabled, versitygw
-# attempts to open object data files with O_DIRECT and automatically falls back
-# to buffered I/O when O_DIRECT is not supported by the filesystem/open call.
-# Some systems may still enforce alignment constraints for direct I/O. The
-# VGW_POSIX_IO_BUFFER_SIZE setting can be used to tune buffered read/write
-# chunk sizing while keeping O_DIRECT best-effort behavior enabled.
+# reads and writes on the posix and scoutfs backends. This is disabled by
+# default. When enabled, versitygw attempts to open object data files with
+# O_DIRECT and automatically falls back to buffered I/O when O_DIRECT is not
+# supported by the filesystem/open call. Some systems may still enforce
+# alignment constraints for direct I/O. For the posix backend, the
+# VGW_POSIX_IO_BUFFER_SIZE setting can tune buffered read/write chunk sizing
+# while keeping O_DIRECT best-effort behavior enabled.
 #VGW_ENABLE_O_DIRECT=false
 
 # The VGW_DEFAULT_ETAG option sets the ETag value returned for objects that do
@@ -767,6 +768,7 @@ ROOT_SECRET_ACCESS_KEY=
 # give feedback to clients about object state and offer ability to request
 # data to be staged back to disk without the client dealing with long
 # request timeout settings.
+# VGW_ENABLE_O_DIRECT also applies to ScoutFS; see the POSIX section above.
 
 # The VGW_SCOUTFS_GLACIER option enables the following Glacier API behavior.
 # GET object:  if file offline, return invalid object state