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Don't evict gofer.dentries with inotify watches before saving. 

PiperOrigin-RevId: 343959348
This commit is contained in:
Jamie Liu 2020-11-23 17:24:20 -08:00 committed by gVisor bot
parent a94663ee56
commit 986683124c
1 changed files with 26 additions and 26 deletions
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52
pkg/sentry/fsimpl/gofer/gofer.go
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@ -1353,16 +1353,11 @@ func (d *dentry) checkCachingLocked(ctx context.Context) {
return
}
if refs > 0 {
if d.cached {
// This isn't strictly necessary (fs.cachedDentries is permitted to
// contain dentries with non-zero refs, which are skipped by
// fs.evictCachedDentryLocked() upon reaching the end of the LRU),
// but since we are already holding fs.renameMu for writing we may
// as well.
d.fs.cachedDentries.Remove(d)
d.fs.cachedDentriesLen--
d.cached = false
}
// This isn't strictly necessary (fs.cachedDentries is permitted to
// contain dentries with non-zero refs, which are skipped by
// fs.evictCachedDentryLocked() upon reaching the end of the LRU), but
// since we are already holding fs.renameMu for writing we may as well.
d.removeFromCacheLocked()
return
}
// Deleted and invalidated dentries with zero references are no longer
@ -1371,20 +1366,18 @@ func (d *dentry) checkCachingLocked(ctx context.Context) {
if d.isDeleted() {
d.watches.HandleDeletion(ctx)
}
if d.cached {
d.fs.cachedDentries.Remove(d)
d.fs.cachedDentriesLen--
d.cached = false
}
d.removeFromCacheLocked()
d.destroyLocked(ctx)
return
}
// If d still has inotify watches and it is not deleted or invalidated, we
// cannot cache it and allow it to be evicted. Otherwise, we will lose its
// watches, even if a new dentry is created for the same file in the future.
// Note that the size of d.watches cannot concurrently transition from zero
// to non-zero, because adding a watch requires holding a reference on d.
// If d still has inotify watches and it is not deleted or invalidated, it
// can't be evicted. Otherwise, we will lose its watches, even if a new
// dentry is created for the same file in the future. Note that the size of
// d.watches cannot concurrently transition from zero to non-zero, because
// adding a watch requires holding a reference on d.
if d.watches.Size() > 0 {
// As in the refs > 0 case, this is not strictly necessary.
d.removeFromCacheLocked()
return
}
@ -1415,6 +1408,15 @@ func (d *dentry) checkCachingLocked(ctx context.Context) {
}
}
// Preconditions: d.fs.renameMu must be locked for writing.
func (d *dentry) removeFromCacheLocked() {
if d.cached {
d.fs.cachedDentries.Remove(d)
d.fs.cachedDentriesLen--
d.cached = false
}
}
// Precondition: fs.renameMu must be locked for writing; it may be temporarily
// unlocked.
func (fs *filesystem) evictAllCachedDentriesLocked(ctx context.Context) {
@ -1428,12 +1430,10 @@ func (fs *filesystem) evictAllCachedDentriesLocked(ctx context.Context) {
// * fs.cachedDentriesLen != 0.
func (fs *filesystem) evictCachedDentryLocked(ctx context.Context) {
victim := fs.cachedDentries.Back()
fs.cachedDentries.Remove(victim)
fs.cachedDentriesLen--
victim.cached = false
// victim.refs may have become non-zero from an earlier path resolution
// since it was inserted into fs.cachedDentries.
if atomic.LoadInt64(&victim.refs) == 0 {
victim.removeFromCacheLocked()
// victim.refs or victim.watches.Size() may have become non-zero from an
// earlier path resolution since it was inserted into fs.cachedDentries.
if atomic.LoadInt64(&victim.refs) == 0 && victim.watches.Size() == 0 {
if victim.parent != nil {
victim.parent.dirMu.Lock()
if !victim.vfsd.IsDead() {