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authorJamie Liu <jamieliu@google.com>2021-08-30 12:37:33 -0700
committergVisor bot <gvisor-bot@google.com>2021-08-30 12:40:08 -0700
commit574c6542a538bc2917fc95e443cf0976946db1c0 (patch)
treee21572a4f872a2865cae8213571943037b313105
parent9625071e6dd6d949f6bd443910eaf56ce1c9762d (diff)
Use specialFileFD handles in specialFileFD.Stat().
PiperOrigin-RevId: 393831108
-rw-r--r--pkg/sentry/fsimpl/gofer/gofer.go60
1 files changed, 35 insertions, 25 deletions
diff --git a/pkg/sentry/fsimpl/gofer/gofer.go b/pkg/sentry/fsimpl/gofer/gofer.go
index bd6b30397..43440ec19 100644
--- a/pkg/sentry/fsimpl/gofer/gofer.go
+++ b/pkg/sentry/fsimpl/gofer/gofer.go
@@ -995,7 +995,7 @@ func (d *dentry) refreshSizeLocked(ctx context.Context) error {
if d.writeFD < 0 {
d.handleMu.RUnlock()
// Ask the gofer if we don't have a host FD.
- return d.updateFromGetattrLocked(ctx)
+ return d.updateFromGetattrLocked(ctx, p9file{})
}
var stat unix.Statx_t
@@ -1014,33 +1014,35 @@ func (d *dentry) updateFromGetattr(ctx context.Context) error {
// updating stale attributes in d.updateFromP9AttrsLocked().
d.metadataMu.Lock()
defer d.metadataMu.Unlock()
- return d.updateFromGetattrLocked(ctx)
+ return d.updateFromGetattrLocked(ctx, p9file{})
}
// Preconditions:
// * !d.isSynthetic().
// * d.metadataMu is locked.
// +checklocks:d.metadataMu
-func (d *dentry) updateFromGetattrLocked(ctx context.Context) error {
- // Use d.readFile or d.writeFile, which represent 9P FIDs that have been
- // opened, in preference to d.file, which represents a 9P fid that has not.
- // This may be significantly more efficient in some implementations. Prefer
- // d.writeFile over d.readFile since some filesystem implementations may
- // update a writable handle's metadata after writes to that handle, without
- // making metadata updates immediately visible to read-only handles
- // representing the same file.
- d.handleMu.RLock()
- handleMuRLocked := true
- var file p9file
- switch {
- case !d.writeFile.isNil():
- file = d.writeFile
- case !d.readFile.isNil():
- file = d.readFile
- default:
- file = d.file
- d.handleMu.RUnlock()
- handleMuRLocked = false
+func (d *dentry) updateFromGetattrLocked(ctx context.Context, file p9file) error {
+ handleMuRLocked := false
+ if file.isNil() {
+ // Use d.readFile or d.writeFile, which represent 9P FIDs that have
+ // been opened, in preference to d.file, which represents a 9P fid that
+ // has not. This may be significantly more efficient in some
+ // implementations. Prefer d.writeFile over d.readFile since some
+ // filesystem implementations may update a writable handle's metadata
+ // after writes to that handle, without making metadata updates
+ // immediately visible to read-only handles representing the same file.
+ d.handleMu.RLock()
+ switch {
+ case !d.writeFile.isNil():
+ file = d.writeFile
+ handleMuRLocked = true
+ case !d.readFile.isNil():
+ file = d.readFile
+ handleMuRLocked = true
+ default:
+ file = d.file
+ d.handleMu.RUnlock()
+ }
}
_, attrMask, attr, err := file.getAttr(ctx, dentryAttrMask())
@@ -2044,9 +2046,17 @@ func (fd *fileDescription) Stat(ctx context.Context, opts vfs.StatOptions) (linu
d := fd.dentry()
const validMask = uint32(linux.STATX_MODE | linux.STATX_UID | linux.STATX_GID | linux.STATX_ATIME | linux.STATX_MTIME | linux.STATX_CTIME | linux.STATX_SIZE | linux.STATX_BLOCKS | linux.STATX_BTIME)
if !d.cachedMetadataAuthoritative() && opts.Mask&validMask != 0 && opts.Sync != linux.AT_STATX_DONT_SYNC {
- // TODO(jamieliu): Use specialFileFD.handle.file for the getattr if
- // available?
- if err := d.updateFromGetattr(ctx); err != nil {
+ // Use specialFileFD.handle.file for the getattr if available, for the
+ // same reason that we try to use open file handles in
+ // dentry.updateFromGetattrLocked().
+ var file p9file
+ if sffd, ok := fd.vfsfd.Impl().(*specialFileFD); ok {
+ file = sffd.handle.file
+ }
+ d.metadataMu.Lock()
+ err := d.updateFromGetattrLocked(ctx, file)
+ d.metadataMu.Unlock()
+ if err != nil {
return linux.Statx{}, err
}
}