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Lock gofer.dentry.dataMu before SetAttr RPC modifying file size.

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PiperOrigin-RevId: 387427887
This commit is contained in:
Jamie Liu
2021-07-28 13:50:12 -07:00
committed by gVisor bot
parent 964fb3ca76
commit 44efc282fe
1 changed files with 23 additions and 5 deletions
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pkg/sentry/fsimpl/gofer/gofer.go
+23 -5
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@@ -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()
}
}