diff options
| -rw-r--r-- | pkg/sentry/fsimpl/gofer/gofer.go | 28 |
1 files changed, 23 insertions, 5 deletions
diff --git a/pkg/sentry/fsimpl/gofer/gofer.go b/pkg/sentry/fsimpl/gofer/gofer.go index ec8d58cc9..25d2e39d6 100644 --- a/pkg/sentry/fsimpl/gofer/gofer.go +++ b/pkg/sentry/fsimpl/gofer/gofer.go @@ -1161,6 +1161,13 @@ func (d *dentry) setStat(ctx context.Context, creds *auth.Credentials, opts *vfs if !d.isSynthetic() { if stat.Mask != 0 { + if stat.Mask&linux.STATX_SIZE != 0 { + // d.dataMu must be held around the update to both the remote + // file's size and d.size to serialize with writeback (which + // might otherwise write data back up to the old d.size after + // the remote file has been truncated). + d.dataMu.Lock() + } if err := d.file.setAttr(ctx, p9.SetAttrMask{ Permissions: stat.Mask&linux.STATX_MODE != 0, UID: stat.Mask&linux.STATX_UID != 0, @@ -1180,13 +1187,16 @@ func (d *dentry) setStat(ctx context.Context, creds *auth.Credentials, opts *vfs MTimeSeconds: uint64(stat.Mtime.Sec), MTimeNanoSeconds: uint64(stat.Mtime.Nsec), }); err != nil { + if stat.Mask&linux.STATX_SIZE != 0 { + d.dataMu.Unlock() // +checklocksforce: locked conditionally above + } return err } if stat.Mask&linux.STATX_SIZE != 0 { // d.size should be kept up to date, and privatized // copy-on-write mappings of truncated pages need to be // invalidated, even if InteropModeShared is in effect. - d.updateSizeLocked(stat.Size) + d.updateSizeAndUnlockDataMuLocked(stat.Size) // +checklocksforce: locked conditionally above } } if d.fs.opts.interop == InteropModeShared { @@ -1249,6 +1259,14 @@ func (d *dentry) doAllocate(ctx context.Context, offset, length uint64, allocate // Preconditions: d.metadataMu must be locked. func (d *dentry) updateSizeLocked(newSize uint64) { d.dataMu.Lock() + d.updateSizeAndUnlockDataMuLocked(newSize) +} + +// Preconditions: d.metadataMu and d.dataMu must be locked. +// +// Postconditions: d.dataMu is unlocked. +// +checklocksrelease:d.dataMu +func (d *dentry) updateSizeAndUnlockDataMuLocked(newSize uint64) { oldSize := d.size atomic.StoreUint64(&d.size, newSize) // d.dataMu must be unlocked to lock d.mapsMu and invalidate mappings @@ -1257,9 +1275,9 @@ func (d *dentry) updateSizeLocked(newSize uint64) { // contents beyond the new d.size. (We are still holding d.metadataMu, // so we can't race with Write or another truncate.) d.dataMu.Unlock() - if d.size < oldSize { + if newSize < oldSize { oldpgend, _ := hostarch.PageRoundUp(oldSize) - newpgend, _ := hostarch.PageRoundUp(d.size) + newpgend, _ := hostarch.PageRoundUp(newSize) if oldpgend != newpgend { d.mapsMu.Lock() d.mappings.Invalidate(memmap.MappableRange{newpgend, oldpgend}, memmap.InvalidateOpts{ @@ -1275,8 +1293,8 @@ func (d *dentry) updateSizeLocked(newSize uint64) { // truncated pages have been removed from the remote file, they // should be dropped without being written back. d.dataMu.Lock() - d.cache.Truncate(d.size, d.fs.mfp.MemoryFile()) - d.dirty.KeepClean(memmap.MappableRange{d.size, oldpgend}) + d.cache.Truncate(newSize, d.fs.mfp.MemoryFile()) + d.dirty.KeepClean(memmap.MappableRange{newSize, oldpgend}) d.dataMu.Unlock() } } |