Merge pull request #6265 from ipfs/revert-6261-fix/fd-limit

Revert "raise default fd limit to 8192"

cmd/ipfs/util/ulimit.go

 package util
 
 import (
+	"errors"
 	"fmt"
 	"os"
 	"strconv"
@@ -20,25 +21,26 @@ var (
 	setLimit func(uint64, uint64) error
 )
 
-// minimum file descriptor limit before we complain
-const minFds = 2048
+// maxFds is the maximum number of file descriptors that go-ipfs
+// can use. The default value is 2048. This can be overwritten by the
+// IPFS_FD_MAX env variable
+var maxFds = uint64(2048)
 
-// default max file descriptor limit.
-const maxFds = 8192
-
-// userMaxFDs returns the value of IPFS_FD_MAX
-func userMaxFDs() uint64 {
+// setMaxFds sets the maxFds value from IPFS_FD_MAX
+// env variable if it's present on the system
+func setMaxFds() {
 	// check if the IPFS_FD_MAX is set up and if it does
 	// not have a valid fds number notify the user
 	if val := os.Getenv("IPFS_FD_MAX"); val != "" {
+
 		fds, err := strconv.ParseUint(val, 10, 64)
 		if err != nil {
 			log.Errorf("bad value for IPFS_FD_MAX: %s", err)
-			return 0
+			return
 		}
-		return fds
+
+		maxFds = fds
 	}
-	return 0
 }
 
 // ManageFdLimit raise the current max file descriptor count
@@ -48,12 +50,7 @@ func ManageFdLimit() (changed bool, newLimit uint64, err error) {
 		return false, 0, nil
 	}
 
-	targetLimit := uint64(maxFds)
-	userLimit := userMaxFDs()
-	if userLimit > 0 {
-		targetLimit = userLimit
-	}
-
+	setMaxFds()
 	soft, hard, err := getLimit()
 	if err != nil {
 		return false, 0, err
@@ -68,47 +65,23 @@ func ManageFdLimit() (changed bool, newLimit uint64, err error) {
 	// the hard limit acts as a ceiling for the soft limit
 	// an unprivileged process may only set it's soft limit to a
 	// alue in the range from 0 up to the hard limit
-	err = setLimit(targetLimit, targetLimit)
-	switch err {
-	case nil:
-		newLimit = targetLimit
-	case syscall.EPERM:
-		// lower limit if necessary.
-		if targetLimit > hard {
-			targetLimit = hard
+	if err = setLimit(maxFds, maxFds); err != nil {
+		if err != syscall.EPERM {
+			return false, 0, fmt.Errorf("error setting: ulimit: %s", err)
 		}
 
 		// the process does not have permission so we should only
 		// set the soft value
-		err = setLimit(targetLimit, hard)
-		if err != nil {
-			err = fmt.Errorf("error setting ulimit wihout hard limit: %s", err)
-			break
-		}
-		newLimit = targetLimit
-
-		// Warn on lowered limit.
-
-		if newLimit < userLimit {
-			err = fmt.Errorf(
-				"failed to raise ulimit to IPFS_FD_MAX (%d): set to %d",
-				userLimit,
-				newLimit,
+		if maxFds > hard {
+			return false, 0, errors.New(
+				"cannot set rlimit, IPFS_FD_MAX is larger than the hard limit",
 			)
-			break
 		}
 
-		if userLimit == 0 && newLimit < minFds {
-			err = fmt.Errorf(
-				"failed to raise ulimit to minimum %d: set to %d",
-				minFds,
-				newLimit,
-			)
-			break
+		if err = setLimit(maxFds, hard); err != nil {
+			return false, 0, fmt.Errorf("error setting ulimit wihout hard limit: %s", err)
 		}
-	default:
-		err = fmt.Errorf("error setting: ulimit: %s", err)
 	}
 
-	return newLimit > 0, newLimit, err
+	return true, maxFds, nil
 }