diff options
Diffstat (limited to 'pkg/sentry/fs/dirent.go')
| -rw-r--r-- | pkg/sentry/fs/dirent.go | 84 |
1 files changed, 47 insertions, 37 deletions
diff --git a/pkg/sentry/fs/dirent.go b/pkg/sentry/fs/dirent.go index 3a45e9041..8d7660e79 100644 --- a/pkg/sentry/fs/dirent.go +++ b/pkg/sentry/fs/dirent.go @@ -488,11 +488,11 @@ func (d *Dirent) walk(ctx context.Context, root *Dirent, name string, walkMayUnl // Slow path: load the InodeOperations into memory. Since this is a hot path and the lookup may be // expensive, if possible release the lock and re-acquire it. if walkMayUnlock { - d.mu.Unlock() + d.mu.Unlock() // +checklocksforce: results in an inconsistent block. } c, err := d.Inode.Lookup(ctx, name) if walkMayUnlock { - d.mu.Lock() + d.mu.Lock() // +checklocksforce: see above. } // No dice. if err != nil { @@ -594,21 +594,27 @@ func (d *Dirent) exists(ctx context.Context, root *Dirent, name string) bool { // lockDirectory should be called for any operation that changes this `d`s // children (creating or removing them). -func (d *Dirent) lockDirectory() func() { +// +checklocksacquire:d.dirMu +// +checklocksacquire:d.mu +func (d *Dirent) lockDirectory() { renameMu.RLock() d.dirMu.Lock() d.mu.Lock() - return func() { - d.mu.Unlock() - d.dirMu.Unlock() - renameMu.RUnlock() - } +} + +// unlockDirectory is the reverse of lockDirectory. +// +checklocksrelease:d.dirMu +// +checklocksrelease:d.mu +func (d *Dirent) unlockDirectory() { + d.mu.Unlock() + d.dirMu.Unlock() + renameMu.RUnlock() // +checklocksforce: see lockDirectory. } // Create creates a new regular file in this directory. func (d *Dirent) Create(ctx context.Context, root *Dirent, name string, flags FileFlags, perms FilePermissions) (*File, error) { - unlock := d.lockDirectory() - defer unlock() + d.lockDirectory() + defer d.unlockDirectory() // Does something already exist? if d.exists(ctx, root, name) { @@ -670,8 +676,8 @@ func (d *Dirent) finishCreate(ctx context.Context, child *Dirent, name string) { // genericCreate executes create if name does not exist. Removes a negative Dirent at name if // create succeeds. func (d *Dirent) genericCreate(ctx context.Context, root *Dirent, name string, create func() error) error { - unlock := d.lockDirectory() - defer unlock() + d.lockDirectory() + defer d.unlockDirectory() // Does something already exist? if d.exists(ctx, root, name) { @@ -1021,8 +1027,8 @@ func (d *Dirent) Remove(ctx context.Context, root *Dirent, name string, dirPath panic("Dirent.Remove: root must not be nil") } - unlock := d.lockDirectory() - defer unlock() + d.lockDirectory() + defer d.unlockDirectory() // Try to walk to the node. child, err := d.walk(ctx, root, name, false /* may unlock */) @@ -1082,8 +1088,8 @@ func (d *Dirent) RemoveDirectory(ctx context.Context, root *Dirent, name string) panic("Dirent.Remove: root must not be nil") } - unlock := d.lockDirectory() - defer unlock() + d.lockDirectory() + defer d.unlockDirectory() // Check for dots. if name == "." { @@ -1259,17 +1265,15 @@ func (d *Dirent) dropExtendedReference() { d.Inode.MountSource.fscache.Remove(d) } -// lockForRename takes locks on oldParent and newParent as required by Rename -// and returns a function that will unlock the locks taken. The returned -// function must be called even if a non-nil error is returned. -func lockForRename(oldParent *Dirent, oldName string, newParent *Dirent, newName string) (func(), error) { +// lockForRename takes locks on oldParent and newParent as required by Rename. +// On return, unlockForRename must always be called, even with an error. +// +checklocksacquire:oldParent.mu +// +checklocksacquire:newParent.mu +func lockForRename(oldParent *Dirent, oldName string, newParent *Dirent, newName string) error { renameMu.Lock() if oldParent == newParent { oldParent.mu.Lock() - return func() { - oldParent.mu.Unlock() - renameMu.Unlock() - }, nil + return nil // +checklocksforce: only one lock exists. } // Renaming between directories is a bit subtle: @@ -1297,11 +1301,7 @@ func lockForRename(oldParent *Dirent, oldName string, newParent *Dirent, newName // itself. err = unix.EINVAL } - return func() { - newParent.mu.Unlock() - oldParent.mu.Unlock() - renameMu.Unlock() - }, err + return err } child = p } @@ -1310,11 +1310,21 @@ func lockForRename(oldParent *Dirent, oldName string, newParent *Dirent, newName // have no relationship; in either case we can do this: newParent.mu.Lock() oldParent.mu.Lock() - return func() { + return nil +} + +// unlockForRename is the opposite of lockForRename. +// +checklocksrelease:oldParent.mu +// +checklocksrelease:newParent.mu +func unlockForRename(oldParent, newParent *Dirent) { + if oldParent == newParent { oldParent.mu.Unlock() - newParent.mu.Unlock() - renameMu.Unlock() - }, nil + renameMu.Unlock() // +checklocksforce: only one lock exists. + return + } + newParent.mu.Unlock() + oldParent.mu.Unlock() + renameMu.Unlock() // +checklocksforce: not tracked. } func (d *Dirent) checkSticky(ctx context.Context, victim *Dirent) error { @@ -1353,8 +1363,8 @@ func (d *Dirent) MayDelete(ctx context.Context, root *Dirent, name string) error return err } - unlock := d.lockDirectory() - defer unlock() + d.lockDirectory() + defer d.unlockDirectory() victim, err := d.walk(ctx, root, name, true /* may unlock */) if err != nil { @@ -1392,8 +1402,8 @@ func Rename(ctx context.Context, root *Dirent, oldParent *Dirent, oldName string } // Acquire global renameMu lock, and mu locks on oldParent/newParent. - unlock, err := lockForRename(oldParent, oldName, newParent, newName) - defer unlock() + err := lockForRename(oldParent, oldName, newParent, newName) + defer unlockForRename(oldParent, newParent) if err != nil { return err } |