diff options
Diffstat (limited to 'pkg/sentry/fs/inode.go')
| -rw-r--r-- | pkg/sentry/fs/inode.go | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/pkg/sentry/fs/inode.go b/pkg/sentry/fs/inode.go index a889586aa..e4aae1135 100644 --- a/pkg/sentry/fs/inode.go +++ b/pkg/sentry/fs/inode.go @@ -15,6 +15,8 @@ package fs import ( + "sync" + "gvisor.dev/gvisor/pkg/abi/linux" "gvisor.dev/gvisor/pkg/log" "gvisor.dev/gvisor/pkg/metric" @@ -55,6 +57,12 @@ type Inode struct { // overlay is the overlay entry for this Inode. overlay *overlayEntry + + // appendMu is used to synchronize write operations into files which + // have been opened with O_APPEND. Operations which change a file size + // have to take this lock for read. Write operations to files with + // O_APPEND have to take this lock for write. + appendMu sync.RWMutex `state:"nosave"` } // LockCtx is an Inode's lock context and contains different personalities of locks; both @@ -337,6 +345,8 @@ func (i *Inode) Truncate(ctx context.Context, d *Dirent, size int64) error { if i.overlay != nil { return overlayTruncate(ctx, i.overlay, d, size) } + i.appendMu.RLock() + defer i.appendMu.RUnlock() return i.InodeOperations.Truncate(ctx, i, size) } @@ -438,3 +448,12 @@ func (i *Inode) CheckCapability(ctx context.Context, cp linux.Capability) bool { } return creds.HasCapability(cp) } + +func (i *Inode) lockAppendMu(appendMode bool) func() { + if appendMode { + i.appendMu.Lock() + return i.appendMu.Unlock + } + i.appendMu.RLock() + return i.appendMu.RUnlock +} |