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Allow VFS2 gofer client to mmap from sentry page cache when forced.

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PiperOrigin-RevId: 381982257
This commit is contained in:
Jamie Liu
2021-06-28 17:43:23 -07:00
committed by gVisor bot
parent 2d899a843b
commit 5b2afd24a7
1 changed files with 24 additions and 24 deletions
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pkg/sentry/fsimpl/gofer/regular_file.go
+24 -24
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@@ -678,28 +678,28 @@ func (fd *regularFileFD) Sync(ctx context.Context) error {
// ConfigureMMap implements vfs.FileDescriptionImpl.ConfigureMMap.
func (fd *regularFileFD) ConfigureMMap(ctx context.Context, opts *memmap.MMapOpts) error {
d := fd.dentry()
switch d.fs.opts.interop {
case InteropModeExclusive:
// Any mapping is fine.
case InteropModeWritethrough:
// Shared writable mappings require a host FD, since otherwise we can't
// synchronously flush memory-mapped writes to the remote file.
if opts.Private || !opts.MaxPerms.Write {
break
// Force sentry page caching at your own risk.
if !d.fs.opts.forcePageCache {
switch d.fs.opts.interop {
case InteropModeExclusive:
// Any mapping is fine.
case InteropModeWritethrough:
// Shared writable mappings require a host FD, since otherwise we
// can't synchronously flush memory-mapped writes to the remote
// file.
if opts.Private || !opts.MaxPerms.Write {
break
}
fallthrough
case InteropModeShared:
// All mappings require a host FD to be coherent with other
// filesystem users.
if atomic.LoadInt32(&d.mmapFD) < 0 {
return syserror.ENODEV
}
default:
panic(fmt.Sprintf("unknown InteropMode %v", d.fs.opts.interop))
}
fallthrough
case InteropModeShared:
// All mappings require a host FD to be coherent with other filesystem
// users.
if d.fs.opts.forcePageCache {
// Whether or not we have a host FD, we're not allowed to use it.
return syserror.ENODEV
}
if atomic.LoadInt32(&d.mmapFD) < 0 {
return syserror.ENODEV
}
default:
panic(fmt.Sprintf("unknown InteropMode %v", d.fs.opts.interop))
}
// After this point, d may be used as a memmap.Mappable.
d.pf.hostFileMapperInitOnce.Do(d.pf.hostFileMapper.Init)
@@ -708,12 +708,12 @@ func (fd *regularFileFD) ConfigureMMap(ctx context.Context, opts *memmap.MMapOpt
}
func (d *dentry) mayCachePages() bool {
if d.fs.opts.interop == InteropModeShared {
return false
}
if d.fs.opts.forcePageCache {
return true
}
if d.fs.opts.interop == InteropModeShared {
return false
}
return atomic.LoadInt32(&d.mmapFD) >= 0
}