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zfs: pipe size: default to value of /proc/sys/fs/pipe-max-siz

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Addition by @problame: move getPipeCapacityHint() into platform-specific
code. This has the added benefit of not recognizing the envvar as an
envconst on platform that do not support resizing pipes.  => won't show
up in (zrepl status --raw).Global.Envconst

fixes #424
cloes #449
This commit is contained in:
Lukas Schauer 2021-03-21 21:46:29 +01:00 committed by Christian Schwarz
parent 1e85b1cb5f
commit ee2336a24b
3 changed files with 31 additions and 10 deletions
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13
zfs/zfs.go
View File

@ -26,11 +26,6 @@ import (
"github.com/zrepl/zrepl/zfs/zfscmd" "github.com/zrepl/zrepl/zfs/zfscmd"
) )
var (
ZFSSendPipeCapacityHint = int(envconst.Int64("ZFS_SEND_PIPE_CAPACITY_HINT", 1<<25))
ZFSRecvPipeCapacityHint = int(envconst.Int64("ZFS_RECV_PIPE_CAPACITY_HINT", 1<<25))
)
type DatasetPath struct { type DatasetPath struct {
comps []string comps []string
} }
@ -328,8 +323,8 @@ func absVersion(fs string, v *ZFSSendArgVersion) (full string, err error) {
} }
func pipeWithCapacityHint(capacity int) (r, w *os.File, err error) { func pipeWithCapacityHint(capacity int) (r, w *os.File, err error) {
if capacity <= 0 { if capacity < 0 {
panic(fmt.Sprintf("capacity must be positive %v", capacity)) panic(fmt.Sprintf("capacity must be non-negative, got %v", capacity))
} }
stdoutReader, stdoutWriter, err := os.Pipe() stdoutReader, stdoutWriter, err := os.Pipe()
if err != nil { if err != nil {
@ -858,7 +853,7 @@ func ZFSSend(ctx context.Context, sendArgs ZFSSendArgsValidated) (*SendStream, e
ctx, cancel := context.WithCancel(ctx) ctx, cancel := context.WithCancel(ctx)
// setup stdout with an os.Pipe to control pipe buffer size // setup stdout with an os.Pipe to control pipe buffer size
stdoutReader, stdoutWriter, err := pipeWithCapacityHint(ZFSSendPipeCapacityHint) stdoutReader, stdoutWriter, err := pipeWithCapacityHint(getPipeCapacityHint("ZFS_SEND_PIPE_CAPACITY_HINT"))
if err != nil { if err != nil {
cancel() cancel()
return nil, err return nil, err
@ -1160,7 +1155,7 @@ func ZFSRecv(ctx context.Context, fs string, v *ZFSSendArgVersion, stream io.Rea
stderr := bytes.NewBuffer(make([]byte, 0, RecvStderrBufSiz)) stderr := bytes.NewBuffer(make([]byte, 0, RecvStderrBufSiz))
stdin, stdinWriter, err := pipeWithCapacityHint(ZFSRecvPipeCapacityHint) stdin, stdinWriter, err := pipeWithCapacityHint(getPipeCapacityHint("ZFS_RECV_PIPE_CAPACITY_HINT"))
if err != nil { if err != nil {
return err return err
} }

6
zfs/zfs_pipe.go
View File

@ -7,10 +7,14 @@ import (
"sync" "sync"
) )
func getPipeCapacityHint(envvar string) int {
return 0 // not supported
}
var zfsPipeCapacityNotSupported sync.Once var zfsPipeCapacityNotSupported sync.Once
func trySetPipeCapacity(p *os.File, capacity int) { func trySetPipeCapacity(p *os.File, capacity int) {
if debugEnabled { if debugEnabled && capacity != 0 {
zfsPipeCapacityNotSupported.Do(func() { zfsPipeCapacityNotSupported.Do(func() {
debug("trySetPipeCapacity error: OS does not support setting pipe capacity") debug("trySetPipeCapacity error: OS does not support setting pipe capacity")
}) })

22
zfs/zfs_pipe_linux.go
View File

@ -3,11 +3,33 @@ package zfs
import ( import (
"errors" "errors"
"fmt" "fmt"
"io/ioutil"
"os" "os"
"strconv"
"strings"
"golang.org/x/sys/unix" "golang.org/x/sys/unix"
"github.com/zrepl/zrepl/util/envconst"
) )
func getPipeCapacityHint(envvar string) int {
var capacity int64 = 1 << 25
// Work around a race condition in Linux >= 5.8 related to pipe resizing.
// https://github.com/zrepl/zrepl/issues/424#issuecomment-800370928
// https://bugzilla.kernel.org/show_bug.cgi?id=212295
if _, err := os.Stat("/proc/sys/fs/pipe-max-size"); err == nil {
if dat, err := ioutil.ReadFile("/proc/sys/fs/pipe-max-size"); err == nil {
if capacity, err = strconv.ParseInt(strings.TrimSpace(string(dat)), 10, 64); err != nil {
capacity = 1 << 25
}
}
}
return int(envconst.Int64(envvar, capacity))
}
func trySetPipeCapacity(p *os.File, capacity int) { func trySetPipeCapacity(p *os.File, capacity int) {
res, err := unix.FcntlInt(p.Fd(), unix.F_SETPIPE_SZ, capacity) res, err := unix.FcntlInt(p.Fd(), unix.F_SETPIPE_SZ, capacity)
if err != nil { if err != nil {