pkg/mount.Mount: speedup (remove Mounted check)

kolyshkin · kolyshkin · commit 83ed668688b5 · 2020-03-10T17:06:26.000-07:00
This was added in PR moby#6669 (commit f87afda) because it was otherwise impossible to do a re-mount of already mounted file system. It is way better to just remove the Mounted() check altogether. This change might potentially lead to multiple mounts to the same mount point, so I audited all the users (except tests) and it looks like no one is doing that: * volume/local maintains 'mounted' flag for every volume * pkg/chrootarchive already calls Mounted() before Mount() (so it actually parsed /proc/self/mountinfo twice, oops!) * daemon.mountVolumes() is called for docker cp only, and it is called once * daemon/graphdriver/zfs keeps track of 'mounted' status * daemon/graphdriver/devmapper: ditto * daemon.createSecretsDir() is only called once during container start Surely I might have easily missed something so this needs a careful review. Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
diff --git a/pkg/mount/mount.go b/pkg/mount/mount.go
@@ -97,24 +97,19 @@ func Mounted(mountpoint string) (bool, error) {
 	return len(entries) > 0, nil
 }
 
-// Mount will mount filesystem according to the specified configuration, on the
-// condition that the target path is *not* already mounted. Options must be
-// specified like the mount or fstab unix commands: "opt1=val1,opt2=val2". See
-// flags.go for supported option flags.
+// Mount will mount filesystem according to the specified configuration.
+// Options must be specified like the mount or fstab unix commands:
+// "opt1=val1,opt2=val2". See flags.go for supported option flags.
 func Mount(device, target, mType, options string) error {
 	flag, data := parseOptions(options)
-	if flag&REMOUNT != REMOUNT {
-		if mounted, err := Mounted(target); err != nil || mounted {
-			return err
-		}
-	}
 	return mount(device, target, mType, uintptr(flag), data)
 }
 
-// ForceMount will mount a filesystem according to the specified configuration,
-// *regardless* if the target path is not already mounted. Options must be
-// specified like the mount or fstab unix commands: "opt1=val1,opt2=val2". See
-// flags.go for supported option flags.
+// Mount will mount filesystem according to the specified configuration.
+// Options must be specified like the mount or fstab unix commands:
+// "opt1=val1,opt2=val2". See flags.go for supported option flags.
+//
+// Deprecated: use Mount instead.
 func ForceMount(device, target, mType, options string) error {
 	flag, data := parseOptions(options)
 	return mount(device, target, mType, uintptr(flag), data)
