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-rw-r--r--pkg/sentry/fsimpl/ext/dentry.go11
-rw-r--r--pkg/sentry/fsimpl/gofer/directory.go1
-rw-r--r--pkg/sentry/fsimpl/gofer/filesystem.go59
-rw-r--r--pkg/sentry/fsimpl/gofer/gofer.go73
-rw-r--r--pkg/sentry/fsimpl/kernfs/kernfs.go7
-rw-r--r--pkg/sentry/fsimpl/overlay/overlay.go5
-rw-r--r--pkg/sentry/fsimpl/tmpfs/directory.go4
-rw-r--r--pkg/sentry/fsimpl/tmpfs/filesystem.go12
-rw-r--r--pkg/sentry/fsimpl/tmpfs/tmpfs.go19
-rw-r--r--pkg/sentry/syscalls/linux/vfs2/inotify.go7
-rw-r--r--pkg/sentry/vfs/anonfs.go7
-rw-r--r--pkg/sentry/vfs/dentry.go32
-rw-r--r--pkg/sentry/vfs/inotify.go108
-rw-r--r--pkg/sentry/vfs/vfs.go3
14 files changed, 273 insertions, 75 deletions
diff --git a/pkg/sentry/fsimpl/ext/dentry.go b/pkg/sentry/fsimpl/ext/dentry.go
index 6bd1a9fc6..55902322a 100644
--- a/pkg/sentry/fsimpl/ext/dentry.go
+++ b/pkg/sentry/fsimpl/ext/dentry.go
@@ -63,12 +63,17 @@ func (d *dentry) DecRef() {
// InotifyWithParent implements vfs.DentryImpl.InotifyWithParent.
//
-// TODO(gvisor.dev/issue/1479): Implement inotify.
-func (d *dentry) InotifyWithParent(events uint32, cookie uint32, et vfs.EventType) {}
+// TODO(b/134676337): Implement inotify.
+func (d *dentry) InotifyWithParent(events, cookie uint32, et vfs.EventType) {}
// Watches implements vfs.DentryImpl.Watches.
//
-// TODO(gvisor.dev/issue/1479): Implement inotify.
+// TODO(b/134676337): Implement inotify.
func (d *dentry) Watches() *vfs.Watches {
return nil
}
+
+// OnZeroWatches implements vfs.Dentry.OnZeroWatches.
+//
+// TODO(b/134676337): Implement inotify.
+func (d *dentry) OnZeroWatches() {}
diff --git a/pkg/sentry/fsimpl/gofer/directory.go b/pkg/sentry/fsimpl/gofer/directory.go
index 480510b2a..5d83fe363 100644
--- a/pkg/sentry/fsimpl/gofer/directory.go
+++ b/pkg/sentry/fsimpl/gofer/directory.go
@@ -138,6 +138,7 @@ func (fd *directoryFD) IterDirents(ctx context.Context, cb vfs.IterDirentsCallba
fd.dirents = ds
}
+ d.InotifyWithParent(linux.IN_ACCESS, 0, vfs.PathEvent)
if d.cachedMetadataAuthoritative() {
d.touchAtime(fd.vfsfd.Mount())
}
diff --git a/pkg/sentry/fsimpl/gofer/filesystem.go b/pkg/sentry/fsimpl/gofer/filesystem.go
index f065c4bad..0321fd384 100644
--- a/pkg/sentry/fsimpl/gofer/filesystem.go
+++ b/pkg/sentry/fsimpl/gofer/filesystem.go
@@ -371,6 +371,11 @@ func (fs *filesystem) doCreateAt(ctx context.Context, rp *vfs.ResolvingPath, dir
}
parent.touchCMtime()
parent.dirents = nil
+ ev := linux.IN_CREATE
+ if dir {
+ ev |= linux.IN_ISDIR
+ }
+ parent.watches.Notify(name, uint32(ev), 0, vfs.InodeEvent)
return nil
}
if fs.opts.interop == InteropModeShared {
@@ -400,6 +405,11 @@ func (fs *filesystem) doCreateAt(ctx context.Context, rp *vfs.ResolvingPath, dir
}
parent.touchCMtime()
parent.dirents = nil
+ ev := linux.IN_CREATE
+ if dir {
+ ev |= linux.IN_ISDIR
+ }
+ parent.watches.Notify(name, uint32(ev), 0, vfs.InodeEvent)
return nil
}
@@ -530,6 +540,18 @@ func (fs *filesystem) unlinkAt(ctx context.Context, rp *vfs.ResolvingPath, dir b
return err
}
}
+
+ // Generate inotify events for rmdir or unlink.
+ if dir {
+ parent.watches.Notify(name, linux.IN_DELETE|linux.IN_ISDIR, 0, vfs.InodeEvent)
+ } else {
+ var cw *vfs.Watches
+ if child != nil {
+ cw = &child.watches
+ }
+ vfs.InotifyRemoveChild(cw, &parent.watches, name)
+ }
+
if child != nil {
vfsObj.CommitDeleteDentry(&child.vfsd)
child.setDeleted()
@@ -1018,6 +1040,7 @@ func (d *dentry) createAndOpenChildLocked(ctx context.Context, rp *vfs.Resolving
}
childVFSFD = &fd.vfsfd
}
+ d.watches.Notify(name, linux.IN_CREATE, 0, vfs.PathEvent)
return childVFSFD, nil
}
@@ -1203,6 +1226,7 @@ func (fs *filesystem) RenameAt(ctx context.Context, rp *vfs.ResolvingPath, oldPa
newParent.incLinks()
}
}
+ vfs.InotifyRename(ctx, &renamed.watches, &oldParent.watches, &newParent.watches, oldName, newName, renamed.isDir())
return nil
}
@@ -1215,12 +1239,21 @@ func (fs *filesystem) RmdirAt(ctx context.Context, rp *vfs.ResolvingPath) error
func (fs *filesystem) SetStatAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.SetStatOptions) error {
var ds *[]*dentry
fs.renameMu.RLock()
- defer fs.renameMuRUnlockAndCheckCaching(&ds)
d, err := fs.resolveLocked(ctx, rp, &ds)
if err != nil {
+ fs.renameMuRUnlockAndCheckCaching(&ds)
+ return err
+ }
+ if err := d.setStat(ctx, rp.Credentials(), &opts.Stat, rp.Mount()); err != nil {
+ fs.renameMuRUnlockAndCheckCaching(&ds)
return err
}
- return d.setStat(ctx, rp.Credentials(), &opts.Stat, rp.Mount())
+ fs.renameMuRUnlockAndCheckCaching(&ds)
+
+ if ev := vfs.InotifyEventFromStatMask(opts.Stat.Mask); ev != 0 {
+ d.InotifyWithParent(ev, 0, vfs.InodeEvent)
+ }
+ return nil
}
// StatAt implements vfs.FilesystemImpl.StatAt.
@@ -1344,24 +1377,38 @@ func (fs *filesystem) GetxattrAt(ctx context.Context, rp *vfs.ResolvingPath, opt
func (fs *filesystem) SetxattrAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.SetxattrOptions) error {
var ds *[]*dentry
fs.renameMu.RLock()
- defer fs.renameMuRUnlockAndCheckCaching(&ds)
d, err := fs.resolveLocked(ctx, rp, &ds)
if err != nil {
+ fs.renameMuRUnlockAndCheckCaching(&ds)
return err
}
- return d.setxattr(ctx, rp.Credentials(), &opts)
+ if err := d.setxattr(ctx, rp.Credentials(), &opts); err != nil {
+ fs.renameMuRUnlockAndCheckCaching(&ds)
+ return err
+ }
+ fs.renameMuRUnlockAndCheckCaching(&ds)
+
+ d.InotifyWithParent(linux.IN_ATTRIB, 0, vfs.InodeEvent)
+ return nil
}
// RemovexattrAt implements vfs.FilesystemImpl.RemovexattrAt.
func (fs *filesystem) RemovexattrAt(ctx context.Context, rp *vfs.ResolvingPath, name string) error {
var ds *[]*dentry
fs.renameMu.RLock()
- defer fs.renameMuRUnlockAndCheckCaching(&ds)
d, err := fs.resolveLocked(ctx, rp, &ds)
if err != nil {
+ fs.renameMuRUnlockAndCheckCaching(&ds)
+ return err
+ }
+ if err := d.removexattr(ctx, rp.Credentials(), name); err != nil {
+ fs.renameMuRUnlockAndCheckCaching(&ds)
return err
}
- return d.removexattr(ctx, rp.Credentials(), name)
+ fs.renameMuRUnlockAndCheckCaching(&ds)
+
+ d.InotifyWithParent(linux.IN_ATTRIB, 0, vfs.InodeEvent)
+ return nil
}
// PrependPath implements vfs.FilesystemImpl.PrependPath.
diff --git a/pkg/sentry/fsimpl/gofer/gofer.go b/pkg/sentry/fsimpl/gofer/gofer.go
index 43c8153a4..c6c284ff3 100644
--- a/pkg/sentry/fsimpl/gofer/gofer.go
+++ b/pkg/sentry/fsimpl/gofer/gofer.go
@@ -665,6 +665,9 @@ type dentry struct {
pipe *pipe.VFSPipe
locks vfs.FileLocks
+
+ // Inotify watches for this dentry.
+ watches vfs.Watches
}
// dentryAttrMask returns a p9.AttrMask enabling all attributes used by the
@@ -947,6 +950,8 @@ func (d *dentry) setStat(ctx context.Context, creds *auth.Credentials, stat *lin
} else {
atomic.StoreInt64(&d.atime, dentryTimestampFromStatx(stat.Atime))
}
+ // Restore mask bits that we cleared earlier.
+ stat.Mask |= linux.STATX_ATIME
}
if setLocalMtime {
if stat.Mtime.Nsec == linux.UTIME_NOW {
@@ -954,6 +959,8 @@ func (d *dentry) setStat(ctx context.Context, creds *auth.Credentials, stat *lin
} else {
atomic.StoreInt64(&d.mtime, dentryTimestampFromStatx(stat.Mtime))
}
+ // Restore mask bits that we cleared earlier.
+ stat.Mask |= linux.STATX_MTIME
}
atomic.StoreInt64(&d.ctime, now)
if stat.Mask&linux.STATX_SIZE != 0 {
@@ -1051,15 +1058,34 @@ func (d *dentry) decRefLocked() {
}
// InotifyWithParent implements vfs.DentryImpl.InotifyWithParent.
-//
-// TODO(gvisor.dev/issue/1479): Implement inotify.
-func (d *dentry) InotifyWithParent(events uint32, cookie uint32, et vfs.EventType) {}
+func (d *dentry) InotifyWithParent(events, cookie uint32, et vfs.EventType) {
+ if d.isDir() {
+ events |= linux.IN_ISDIR
+ }
+
+ d.fs.renameMu.RLock()
+ // The ordering below is important, Linux always notifies the parent first.
+ if d.parent != nil {
+ d.parent.watches.NotifyWithExclusions(d.name, events, cookie, et, d.isDeleted())
+ }
+ d.watches.Notify("", events, cookie, et)
+ d.fs.renameMu.RUnlock()
+}
// Watches implements vfs.DentryImpl.Watches.
-//
-// TODO(gvisor.dev/issue/1479): Implement inotify.
func (d *dentry) Watches() *vfs.Watches {
- return nil
+ return &d.watches
+}
+
+// OnZeroWatches implements vfs.DentryImpl.OnZeroWatches.
+//
+// If no watches are left on this dentry and it has no references, cache it.
+func (d *dentry) OnZeroWatches() {
+ if atomic.LoadInt64(&d.refs) == 0 {
+ d.fs.renameMu.Lock()
+ d.checkCachingLocked()
+ d.fs.renameMu.Unlock()
+ }
}
// checkCachingLocked should be called after d's reference count becomes 0 or it
@@ -1093,6 +1119,9 @@ func (d *dentry) checkCachingLocked() {
// Deleted and invalidated dentries with zero references are no longer
// reachable by path resolution and should be dropped immediately.
if d.vfsd.IsDead() {
+ if d.isDeleted() {
+ d.watches.HandleDeletion()
+ }
if d.cached {
d.fs.cachedDentries.Remove(d)
d.fs.cachedDentriesLen--
@@ -1101,6 +1130,14 @@ func (d *dentry) checkCachingLocked() {
d.destroyLocked()
return
}
+ // If d still has inotify watches and it is not deleted or invalidated, we
+ // cannot cache it and allow it to be evicted. Otherwise, we will lose its
+ // watches, even if a new dentry is created for the same file in the future.
+ // Note that the size of d.watches cannot concurrently transition from zero
+ // to non-zero, because adding a watch requires holding a reference on d.
+ if d.watches.Size() > 0 {
+ return
+ }
// If d is already cached, just move it to the front of the LRU.
if d.cached {
d.fs.cachedDentries.Remove(d)
@@ -1277,7 +1314,7 @@ func (d *dentry) userXattrSupported() bool {
return filetype == linux.S_IFREG || filetype == linux.S_IFDIR
}
-// Preconditions: !d.isSynthetic(). d.isRegularFile() || d.isDirectory().
+// Preconditions: !d.isSynthetic(). d.isRegularFile() || d.isDir().
func (d *dentry) ensureSharedHandle(ctx context.Context, read, write, trunc bool) error {
// O_TRUNC unconditionally requires us to obtain a new handle (opened with
// O_TRUNC).
@@ -1422,7 +1459,13 @@ func (fd *fileDescription) Stat(ctx context.Context, opts vfs.StatOptions) (linu
// SetStat implements vfs.FileDescriptionImpl.SetStat.
func (fd *fileDescription) SetStat(ctx context.Context, opts vfs.SetStatOptions) error {
- return fd.dentry().setStat(ctx, auth.CredentialsFromContext(ctx), &opts.Stat, fd.vfsfd.Mount())
+ if err := fd.dentry().setStat(ctx, auth.CredentialsFromContext(ctx), &opts.Stat, fd.vfsfd.Mount()); err != nil {
+ return err
+ }
+ if ev := vfs.InotifyEventFromStatMask(opts.Stat.Mask); ev != 0 {
+ fd.dentry().InotifyWithParent(ev, 0, vfs.InodeEvent)
+ }
+ return nil
}
// Listxattr implements vfs.FileDescriptionImpl.Listxattr.
@@ -1437,12 +1480,22 @@ func (fd *fileDescription) Getxattr(ctx context.Context, opts vfs.GetxattrOption
// Setxattr implements vfs.FileDescriptionImpl.Setxattr.
func (fd *fileDescription) Setxattr(ctx context.Context, opts vfs.SetxattrOptions) error {
- return fd.dentry().setxattr(ctx, auth.CredentialsFromContext(ctx), &opts)
+ d := fd.dentry()
+ if err := d.setxattr(ctx, auth.CredentialsFromContext(ctx), &opts); err != nil {
+ return err
+ }
+ d.InotifyWithParent(linux.IN_ATTRIB, 0, vfs.InodeEvent)
+ return nil
}
// Removexattr implements vfs.FileDescriptionImpl.Removexattr.
func (fd *fileDescription) Removexattr(ctx context.Context, name string) error {
- return fd.dentry().removexattr(ctx, auth.CredentialsFromContext(ctx), name)
+ d := fd.dentry()
+ if err := d.removexattr(ctx, auth.CredentialsFromContext(ctx), name); err != nil {
+ return err
+ }
+ d.InotifyWithParent(linux.IN_ATTRIB, 0, vfs.InodeEvent)
+ return nil
}
// LockBSD implements vfs.FileDescriptionImpl.LockBSD.
diff --git a/pkg/sentry/fsimpl/kernfs/kernfs.go b/pkg/sentry/fsimpl/kernfs/kernfs.go
index 07a9dc830..55349f2a3 100644
--- a/pkg/sentry/fsimpl/kernfs/kernfs.go
+++ b/pkg/sentry/fsimpl/kernfs/kernfs.go
@@ -228,7 +228,7 @@ func (d *Dentry) destroy() {
// InotifyWithParent implements vfs.DentryImpl.InotifyWithParent.
//
// TODO(gvisor.dev/issue/1479): Implement inotify.
-func (d *Dentry) InotifyWithParent(events uint32, cookie uint32, et vfs.EventType) {}
+func (d *Dentry) InotifyWithParent(events, cookie uint32, et vfs.EventType) {}
// Watches implements vfs.DentryImpl.Watches.
//
@@ -237,6 +237,11 @@ func (d *Dentry) Watches() *vfs.Watches {
return nil
}
+// OnZeroWatches implements vfs.Dentry.OnZeroWatches.
+//
+// TODO(gvisor.dev/issue/1479): Implement inotify.
+func (d *Dentry) OnZeroWatches() {}
+
// InsertChild inserts child into the vfs dentry cache with the given name under
// this dentry. This does not update the directory inode, so calling this on
// its own isn't sufficient to insert a child into a directory. InsertChild
diff --git a/pkg/sentry/fsimpl/overlay/overlay.go b/pkg/sentry/fsimpl/overlay/overlay.go
index e11a3ff19..e720d4825 100644
--- a/pkg/sentry/fsimpl/overlay/overlay.go
+++ b/pkg/sentry/fsimpl/overlay/overlay.go
@@ -528,6 +528,11 @@ func (d *dentry) Watches() *vfs.Watches {
return nil
}
+// OnZeroWatches implements vfs.DentryImpl.OnZeroWatches.
+//
+// TODO(gvisor.dev/issue/1479): Implement inotify.
+func (d *dentry) OnZeroWatches() {}
+
// iterLayers invokes yield on each layer comprising d, from top to bottom. If
// any call to yield returns false, iterLayer stops iteration.
func (d *dentry) iterLayers(yield func(vd vfs.VirtualDentry, isUpper bool) bool) {
diff --git a/pkg/sentry/fsimpl/tmpfs/directory.go b/pkg/sentry/fsimpl/tmpfs/directory.go
index 913b8a6c5..b172abc15 100644
--- a/pkg/sentry/fsimpl/tmpfs/directory.go
+++ b/pkg/sentry/fsimpl/tmpfs/directory.go
@@ -79,7 +79,6 @@ func (dir *directory) removeChildLocked(child *dentry) {
dir.iterMu.Lock()
dir.childList.Remove(child)
dir.iterMu.Unlock()
- child.unlinked = true
}
type directoryFD struct {
@@ -107,13 +106,14 @@ func (fd *directoryFD) IterDirents(ctx context.Context, cb vfs.IterDirentsCallba
fs := fd.filesystem()
dir := fd.inode().impl.(*directory)
+ defer fd.dentry().InotifyWithParent(linux.IN_ACCESS, 0, vfs.PathEvent)
+
// fs.mu is required to read d.parent and dentry.name.
fs.mu.RLock()
defer fs.mu.RUnlock()
dir.iterMu.Lock()
defer dir.iterMu.Unlock()
- fd.dentry().InotifyWithParent(linux.IN_ACCESS, 0, vfs.PathEvent)
fd.inode().touchAtime(fd.vfsfd.Mount())
if fd.off == 0 {
diff --git a/pkg/sentry/fsimpl/tmpfs/filesystem.go b/pkg/sentry/fsimpl/tmpfs/filesystem.go
index 637d84e04..85d8e37b2 100644
--- a/pkg/sentry/fsimpl/tmpfs/filesystem.go
+++ b/pkg/sentry/fsimpl/tmpfs/filesystem.go
@@ -638,14 +638,16 @@ func (fs *filesystem) RmdirAt(ctx context.Context, rp *vfs.ResolvingPath) error
// SetStatAt implements vfs.FilesystemImpl.SetStatAt.
func (fs *filesystem) SetStatAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.SetStatOptions) error {
fs.mu.RLock()
- defer fs.mu.RUnlock()
d, err := resolveLocked(rp)
if err != nil {
+ fs.mu.RUnlock()
return err
}
if err := d.inode.setStat(ctx, rp.Credentials(), &opts.Stat); err != nil {
+ fs.mu.RUnlock()
return err
}
+ fs.mu.RUnlock()
if ev := vfs.InotifyEventFromStatMask(opts.Stat.Mask); ev != 0 {
d.InotifyWithParent(ev, 0, vfs.InodeEvent)
@@ -788,14 +790,16 @@ func (fs *filesystem) GetxattrAt(ctx context.Context, rp *vfs.ResolvingPath, opt
// SetxattrAt implements vfs.FilesystemImpl.SetxattrAt.
func (fs *filesystem) SetxattrAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.SetxattrOptions) error {
fs.mu.RLock()
- defer fs.mu.RUnlock()
d, err := resolveLocked(rp)
if err != nil {
+ fs.mu.RUnlock()
return err
}
if err := d.inode.setxattr(rp.Credentials(), &opts); err != nil {
+ fs.mu.RUnlock()
return err
}
+ fs.mu.RUnlock()
d.InotifyWithParent(linux.IN_ATTRIB, 0, vfs.InodeEvent)
return nil
@@ -804,14 +808,16 @@ func (fs *filesystem) SetxattrAt(ctx context.Context, rp *vfs.ResolvingPath, opt
// RemovexattrAt implements vfs.FilesystemImpl.RemovexattrAt.
func (fs *filesystem) RemovexattrAt(ctx context.Context, rp *vfs.ResolvingPath, name string) error {
fs.mu.RLock()
- defer fs.mu.RUnlock()
d, err := resolveLocked(rp)
if err != nil {
+ fs.mu.RUnlock()
return err
}
if err := d.inode.removexattr(rp.Credentials(), name); err != nil {
+ fs.mu.RUnlock()
return err
}
+ fs.mu.RUnlock()
d.InotifyWithParent(linux.IN_ATTRIB, 0, vfs.InodeEvent)
return nil
diff --git a/pkg/sentry/fsimpl/tmpfs/tmpfs.go b/pkg/sentry/fsimpl/tmpfs/tmpfs.go
index a94333ee0..a85bfc968 100644
--- a/pkg/sentry/fsimpl/tmpfs/tmpfs.go
+++ b/pkg/sentry/fsimpl/tmpfs/tmpfs.go
@@ -215,11 +215,6 @@ type dentry struct {
// filesystem.mu.
name string
- // unlinked indicates whether this dentry has been unlinked from its parent.
- // It is only set to true on an unlink operation, and never set from true to
- // false. unlinked is protected by filesystem.mu.
- unlinked bool
-
// dentryEntry (ugh) links dentries into their parent directory.childList.
dentryEntry
@@ -259,18 +254,20 @@ func (d *dentry) DecRef() {
}
// InotifyWithParent implements vfs.DentryImpl.InotifyWithParent.
-func (d *dentry) InotifyWithParent(events uint32, cookie uint32, et vfs.EventType) {
+func (d *dentry) InotifyWithParent(events, cookie uint32, et vfs.EventType) {
if d.inode.isDir() {
events |= linux.IN_ISDIR
}
+ d.inode.fs.mu.RLock()
// The ordering below is important, Linux always notifies the parent first.
if d.parent != nil {
- // Note that d.parent or d.name may be stale if there is a concurrent
- // rename operation. Inotify does not provide consistency guarantees.
- d.parent.inode.watches.NotifyWithExclusions(d.name, events, cookie, et, d.unlinked)
+ // tmpfs never calls VFS.InvalidateDentry(), so d.vfsd.IsDead() indicates
+ // that d was deleted.
+ d.parent.inode.watches.NotifyWithExclusions(d.name, events, cookie, et, d.vfsd.IsDead())
}
d.inode.watches.Notify("", events, cookie, et)
+ d.inode.fs.mu.RUnlock()
}
// Watches implements vfs.DentryImpl.Watches.
@@ -278,6 +275,9 @@ func (d *dentry) Watches() *vfs.Watches {
return &d.inode.watches
}
+// OnZeroWatches implements vfs.Dentry.OnZeroWatches.
+func (d *dentry) OnZeroWatches() {}
+
// inode represents a filesystem object.
type inode struct {
// fs is the owning filesystem. fs is immutable.
@@ -336,7 +336,6 @@ func (i *inode) init(impl interface{}, fs *filesystem, kuid auth.KUID, kgid auth
i.ctime = now
i.mtime = now
// i.nlink initialized by caller
- i.watches = vfs.Watches{}
i.impl = impl
}
diff --git a/pkg/sentry/syscalls/linux/vfs2/inotify.go b/pkg/sentry/syscalls/linux/vfs2/inotify.go
index 7d50b6a16..74e5287b7 100644
--- a/pkg/sentry/syscalls/linux/vfs2/inotify.go
+++ b/pkg/sentry/syscalls/linux/vfs2/inotify.go
@@ -116,8 +116,11 @@ func InotifyAddWatch(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kern
}
defer d.DecRef()
- fd = ino.AddWatch(d.Dentry(), mask)
- return uintptr(fd), nil, err
+ fd, err = ino.AddWatch(d.Dentry(), mask)
+ if err != nil {
+ return 0, nil, err
+ }
+ return uintptr(fd), nil, nil
}
// InotifyRmWatch implements the inotify_rm_watch() syscall.
diff --git a/pkg/sentry/vfs/anonfs.go b/pkg/sentry/vfs/anonfs.go
index b7c6b60b8..746af03ec 100644
--- a/pkg/sentry/vfs/anonfs.go
+++ b/pkg/sentry/vfs/anonfs.go
@@ -301,7 +301,7 @@ func (d *anonDentry) DecRef() {
// InotifyWithParent implements DentryImpl.InotifyWithParent.
//
// TODO(gvisor.dev/issue/1479): Implement inotify.
-func (d *anonDentry) InotifyWithParent(events uint32, cookie uint32, et EventType) {}
+func (d *anonDentry) InotifyWithParent(events, cookie uint32, et EventType) {}
// Watches implements DentryImpl.Watches.
//
@@ -309,3 +309,8 @@ func (d *anonDentry) InotifyWithParent(events uint32, cookie uint32, et EventTyp
func (d *anonDentry) Watches() *Watches {
return nil
}
+
+// OnZeroWatches implements Dentry.OnZeroWatches.
+//
+// TODO(gvisor.dev/issue/1479): Implement inotify.
+func (d *anonDentry) OnZeroWatches() {}
diff --git a/pkg/sentry/vfs/dentry.go b/pkg/sentry/vfs/dentry.go
index 24af13eb1..cea3e6955 100644
--- a/pkg/sentry/vfs/dentry.go
+++ b/pkg/sentry/vfs/dentry.go
@@ -113,12 +113,29 @@ type DentryImpl interface {
//
// Note that the events may not actually propagate up to the user, depending
// on the event masks.
- InotifyWithParent(events uint32, cookie uint32, et EventType)
+ InotifyWithParent(events, cookie uint32, et EventType)
// Watches returns the set of inotify watches for the file corresponding to
// the Dentry. Dentries that are hard links to the same underlying file
// share the same watches.
+ //
+ // Watches may return nil if the dentry belongs to a FilesystemImpl that
+ // does not support inotify. If an implementation returns a non-nil watch
+ // set, it must always return a non-nil watch set. Likewise, if an
+ // implementation returns a nil watch set, it must always return a nil watch
+ // set.
+ //
+ // The caller does not need to hold a reference on the dentry.
Watches() *Watches
+
+ // OnZeroWatches is called whenever the number of watches on a dentry drops
+ // to zero. This is needed by some FilesystemImpls (e.g. gofer) to manage
+ // dentry lifetime.
+ //
+ // The caller does not need to hold a reference on the dentry. OnZeroWatches
+ // may acquire inotify locks, so to prevent deadlock, no inotify locks should
+ // be held by the caller.
+ OnZeroWatches()
}
// IncRef increments d's reference count.
@@ -149,17 +166,26 @@ func (d *Dentry) isMounted() bool {
return atomic.LoadUint32(&d.mounts) != 0
}
-// InotifyWithParent notifies all watches on the inodes for this dentry and
+// InotifyWithParent notifies all watches on the targets represented by d and
// its parent of events.
-func (d *Dentry) InotifyWithParent(events uint32, cookie uint32, et EventType) {
+func (d *Dentry) InotifyWithParent(events, cookie uint32, et EventType) {
d.impl.InotifyWithParent(events, cookie, et)
}
// Watches returns the set of inotify watches associated with d.
+//
+// Watches will return nil if d belongs to a FilesystemImpl that does not
+// support inotify.
func (d *Dentry) Watches() *Watches {
return d.impl.Watches()
}
+// OnZeroWatches performs cleanup tasks whenever the number of watches on a
+// dentry drops to zero.
+func (d *Dentry) OnZeroWatches() {
+ d.impl.OnZeroWatches()
+}
+
// The following functions are exported so that filesystem implementations can
// use them. The vfs package, and users of VFS, should not call these
// functions.
diff --git a/pkg/sentry/vfs/inotify.go b/pkg/sentry/vfs/inotify.go
index 7fa7d2d0c..36e7a3767 100644
--- a/pkg/sentry/vfs/inotify.go
+++ b/pkg/sentry/vfs/inotify.go
@@ -49,9 +49,6 @@ const (
// Inotify represents an inotify instance created by inotify_init(2) or
// inotify_init1(2). Inotify implements FileDescriptionImpl.
//
-// Lock ordering:
-// Inotify.mu -> Watches.mu -> Inotify.evMu
-//
// +stateify savable
type Inotify struct {
vfsfd FileDescription
@@ -122,17 +119,31 @@ func NewInotifyFD(ctx context.Context, vfsObj *VirtualFilesystem, flags uint32)
// Release implements FileDescriptionImpl.Release. Release removes all
// watches and frees all resources for an inotify instance.
func (i *Inotify) Release() {
+ var ds []*Dentry
// We need to hold i.mu to avoid a race with concurrent calls to
// Inotify.handleDeletion from Watches. There's no risk of Watches
// accessing this Inotify after the destructor ends, because we remove all
// references to it below.
i.mu.Lock()
- defer i.mu.Unlock()
for _, w := range i.watches {
// Remove references to the watch from the watches set on the target. We
// don't need to worry about the references from i.watches, since this
// file description is about to be destroyed.
- w.set.Remove(i.id)
+ d := w.target
+ ws := d.Watches()
+ // Watchable dentries should never return a nil watch set.
+ if ws == nil {
+ panic("Cannot remove watch from an unwatchable dentry")
+ }
+ ws.Remove(i.id)
+ if ws.Size() == 0 {
+ ds = append(ds, d)
+ }
+ }
+ i.mu.Unlock()
+
+ for _, d := range ds {
+ d.OnZeroWatches()
}
}
@@ -272,20 +283,19 @@ func (i *Inotify) queueEvent(ev *Event) {
// newWatchLocked creates and adds a new watch to target.
//
-// Precondition: i.mu must be locked.
-func (i *Inotify) newWatchLocked(target *Dentry, mask uint32) *Watch {
- targetWatches := target.Watches()
+// Precondition: i.mu must be locked. ws must be the watch set for target d.
+func (i *Inotify) newWatchLocked(d *Dentry, ws *Watches, mask uint32) *Watch {
w := &Watch{
- owner: i,
- wd: i.nextWatchIDLocked(),
- set: targetWatches,
- mask: mask,
+ owner: i,
+ wd: i.nextWatchIDLocked(),
+ target: d,
+ mask: mask,
}
// Hold the watch in this inotify instance as well as the watch set on the
// target.
i.watches[w.wd] = w
- targetWatches.Add(w)
+ ws.Add(w)
return w
}
@@ -312,7 +322,9 @@ func (i *Inotify) handleDeletion(w *Watch) {
// AddWatch constructs a new inotify watch and adds it to the target. It
// returns the watch descriptor returned by inotify_add_watch(2).
-func (i *Inotify) AddWatch(target *Dentry, mask uint32) int32 {
+//
+// The caller must hold a reference on target.
+func (i *Inotify) AddWatch(target *Dentry, mask uint32) (int32, error) {
// Note: Locking this inotify instance protects the result returned by
// Lookup() below. With the lock held, we know for sure the lookup result
// won't become stale because it's impossible for *this* instance to
@@ -320,8 +332,14 @@ func (i *Inotify) AddWatch(target *Dentry, mask uint32) int32 {
i.mu.Lock()
defer i.mu.Unlock()
+ ws := target.Watches()
+ if ws == nil {
+ // While Linux supports inotify watches on all filesystem types, watches on
+ // filesystems like kernfs are not generally useful, so we do not.
+ return 0, syserror.EPERM
+ }
// Does the target already have a watch from this inotify instance?
- if existing := target.Watches().Lookup(i.id); existing != nil {
+ if existing := ws.Lookup(i.id); existing != nil {
newmask := mask
if mask&linux.IN_MASK_ADD != 0 {
// "Add (OR) events to watch mask for this pathname if it already
@@ -329,12 +347,12 @@ func (i *Inotify) AddWatch(target *Dentry, mask uint32) int32 {
newmask |= atomic.LoadUint32(&existing.mask)
}
atomic.StoreUint32(&existing.mask, newmask)
- return existing.wd
+ return existing.wd, nil
}
// No existing watch, create a new watch.
- w := i.newWatchLocked(target, mask)
- return w.wd
+ w := i.newWatchLocked(target, ws, mask)
+ return w.wd, nil
}
// RmWatch looks up an inotify watch for the given 'wd' and configures the
@@ -353,9 +371,19 @@ func (i *Inotify) RmWatch(wd int32) error {
delete(i.watches, wd)
// Remove the watch from the watch target.
- w.set.Remove(w.OwnerID())
+ ws := w.target.Watches()
+ // AddWatch ensures that w.target has a non-nil watch set.
+ if ws == nil {
+ panic("Watched dentry cannot have nil watch set")
+ }
+ ws.Remove(w.OwnerID())
+ remaining := ws.Size()
i.mu.Unlock()
+ if remaining == 0 {
+ w.target.OnZeroWatches()
+ }
+
// Generate the event for the removal.
i.queueEvent(newEvent(wd, "", linux.IN_IGNORED, 0))
@@ -374,6 +402,13 @@ type Watches struct {
ws map[uint64]*Watch
}
+// Size returns the number of watches held by w.
+func (w *Watches) Size() int {
+ w.mu.Lock()
+ defer w.mu.Unlock()
+ return len(w.ws)
+}
+
// Lookup returns the watch owned by an inotify instance with the given id.
// Returns nil if no such watch exists.
//
@@ -459,10 +494,6 @@ func (w *Watches) NotifyWithExclusions(name string, events, cookie uint32, et Ev
func (w *Watches) HandleDeletion() {
w.Notify("", linux.IN_DELETE_SELF, 0, InodeEvent)
- // TODO(gvisor.dev/issue/1479): This doesn't work because maps are not copied
- // by value. Ideally, we wouldn't have this circular locking so we can just
- // notify of IN_DELETE_SELF in the same loop below.
- //
// We can't hold w.mu while calling watch.handleDeletion to preserve lock
// ordering w.r.t to the owner inotify instances. Instead, atomically move
// the watches map into a local variable so we can iterate over it safely.
@@ -495,9 +526,8 @@ type Watch struct {
// Descriptor for this watch. This is unique across an inotify instance.
wd int32
- // set is the watch set containing this watch. It belongs to the target file
- // of this watch.
- set *Watches
+ // target is a dentry representing the watch target. Its watch set contains this watch.
+ target *Dentry
// Events being monitored via this watch. Must be accessed with atomic
// memory operations.
@@ -606,7 +636,7 @@ func (e *Event) setName(name string) {
func (e *Event) sizeOf() int {
s := inotifyEventBaseSize + int(e.len)
if s < inotifyEventBaseSize {
- panic("overflow")
+ panic("Overflowed event size")
}
return s
}
@@ -676,11 +706,15 @@ func InotifyEventFromStatMask(mask uint32) uint32 {
}
// InotifyRemoveChild sends the appriopriate notifications to the watch sets of
-// the child being removed and its parent.
+// the child being removed and its parent. Note that unlike most pairs of
+// parent/child notifications, the child is notified first in this case.
func InotifyRemoveChild(self, parent *Watches, name string) {
- self.Notify("", linux.IN_ATTRIB, 0, InodeEvent)
- parent.Notify(name, linux.IN_DELETE, 0, InodeEvent)
- // TODO(gvisor.dev/issue/1479): implement IN_EXCL_UNLINK.
+ if self != nil {
+ self.Notify("", linux.IN_ATTRIB, 0, InodeEvent)
+ }
+ if parent != nil {
+ parent.Notify(name, linux.IN_DELETE, 0, InodeEvent)
+ }
}
// InotifyRename sends the appriopriate notifications to the watch sets of the
@@ -691,8 +725,14 @@ func InotifyRename(ctx context.Context, renamed, oldParent, newParent *Watches,
dirEv = linux.IN_ISDIR
}
cookie := uniqueid.InotifyCookie(ctx)
- oldParent.Notify(oldName, dirEv|linux.IN_MOVED_FROM, cookie, InodeEvent)
- newParent.Notify(newName, dirEv|linux.IN_MOVED_TO, cookie, InodeEvent)
+ if oldParent != nil {
+ oldParent.Notify(oldName, dirEv|linux.IN_MOVED_FROM, cookie, InodeEvent)
+ }
+ if newParent != nil {
+ newParent.Notify(newName, dirEv|linux.IN_MOVED_TO, cookie, InodeEvent)
+ }
// Somewhat surprisingly, self move events do not have a cookie.
- renamed.Notify("", linux.IN_MOVE_SELF, 0, InodeEvent)
+ if renamed != nil {
+ renamed.Notify("", linux.IN_MOVE_SELF, 0, InodeEvent)
+ }
}
diff --git a/pkg/sentry/vfs/vfs.go b/pkg/sentry/vfs/vfs.go
index 9acca8bc7..58c7ad778 100644
--- a/pkg/sentry/vfs/vfs.go
+++ b/pkg/sentry/vfs/vfs.go
@@ -24,6 +24,9 @@
// Locks acquired by FilesystemImpls between Prepare{Delete,Rename}Dentry and Commit{Delete,Rename*}Dentry
// VirtualFilesystem.filesystemsMu
// EpollInstance.mu
+// Inotify.mu
+// Watches.mu
+// Inotify.evMu
// VirtualFilesystem.fsTypesMu
//
// Locking Dentry.mu in multiple Dentries requires holding
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-05 21:06:13 +0000