diff options
author | gVisor bot <gvisor-bot@google.com> | 2020-08-26 04:06:56 +0000 |
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committer | gVisor bot <gvisor-bot@google.com> | 2020-08-26 04:06:56 +0000 |
commit | 68eb313a6da88ae9192571d7f08f7a7dbeb495e1 (patch) | |
tree | 6974dbdb721bfa0a8b2ada517f435f2cad2aa4f1 /pkg/sentry/kernel/fs_context.go | |
parent | 11be6aad17d54dc7085ba4e585f37d54a89f0cf5 (diff) | |
parent | df3c105f49865a48f0c07c79ab84b1bf351a49f8 (diff) |
Merge release-20200818.0-56-gdf3c105f4 (automated)
Diffstat (limited to 'pkg/sentry/kernel/fs_context.go')
-rw-r--r-- | pkg/sentry/kernel/fs_context.go | 89 |
1 files changed, 47 insertions, 42 deletions
diff --git a/pkg/sentry/kernel/fs_context.go b/pkg/sentry/kernel/fs_context.go index 8f2d36d5a..d46d1e1c1 100644 --- a/pkg/sentry/kernel/fs_context.go +++ b/pkg/sentry/kernel/fs_context.go @@ -18,7 +18,6 @@ import ( "fmt" "gvisor.dev/gvisor/pkg/context" - "gvisor.dev/gvisor/pkg/refs" "gvisor.dev/gvisor/pkg/sentry/fs" "gvisor.dev/gvisor/pkg/sentry/vfs" "gvisor.dev/gvisor/pkg/sync" @@ -30,7 +29,7 @@ import ( // // +stateify savable type FSContext struct { - refs.AtomicRefCount + FSContextRefs // mu protects below. mu sync.Mutex `state:"nosave"` @@ -64,7 +63,7 @@ func newFSContext(root, cwd *fs.Dirent, umask uint) *FSContext { cwd: cwd, umask: umask, } - f.EnableLeakCheck("kernel.FSContext") + f.EnableLeakCheck() return &f } @@ -77,54 +76,56 @@ func NewFSContextVFS2(root, cwd vfs.VirtualDentry, umask uint) *FSContext { cwdVFS2: cwd, umask: umask, } - f.EnableLeakCheck("kernel.FSContext") + f.EnableLeakCheck() return &f } -// destroy is the destructor for an FSContext. +// DecRef implements RefCounter.DecRef. // -// This will call DecRef on both root and cwd Dirents. If either call to -// DecRef returns an error, then it will be propagated. If both calls to -// DecRef return an error, then the one from root.DecRef will be propagated. +// When f reaches zero references, DecRef will be called on both root and cwd +// Dirents. // // Note that there may still be calls to WorkingDirectory() or RootDirectory() // (that return nil). This is because valid references may still be held via // proc files or other mechanisms. -func (f *FSContext) destroy(ctx context.Context) { - // Hold f.mu so that we don't race with RootDirectory() and - // WorkingDirectory(). - f.mu.Lock() - defer f.mu.Unlock() - - if VFS2Enabled { - f.rootVFS2.DecRef(ctx) - f.rootVFS2 = vfs.VirtualDentry{} - f.cwdVFS2.DecRef(ctx) - f.cwdVFS2 = vfs.VirtualDentry{} - } else { - f.root.DecRef(ctx) - f.root = nil - f.cwd.DecRef(ctx) - f.cwd = nil - } -} - -// DecRef implements RefCounter.DecRef with destructor f.destroy. func (f *FSContext) DecRef(ctx context.Context) { - f.DecRefWithDestructor(ctx, f.destroy) + f.FSContextRefs.DecRef(func() { + // Hold f.mu so that we don't race with RootDirectory() and + // WorkingDirectory(). + f.mu.Lock() + defer f.mu.Unlock() + + if VFS2Enabled { + f.rootVFS2.DecRef(ctx) + f.rootVFS2 = vfs.VirtualDentry{} + f.cwdVFS2.DecRef(ctx) + f.cwdVFS2 = vfs.VirtualDentry{} + } else { + f.root.DecRef(ctx) + f.root = nil + f.cwd.DecRef(ctx) + f.cwd = nil + } + }) } // Fork forks this FSContext. // -// This is not a valid call after destroy. +// This is not a valid call after f is destroyed. func (f *FSContext) Fork() *FSContext { f.mu.Lock() defer f.mu.Unlock() if VFS2Enabled { + if !f.cwdVFS2.Ok() { + panic("FSContext.Fork() called after destroy") + } f.cwdVFS2.IncRef() f.rootVFS2.IncRef() } else { + if f.cwd == nil { + panic("FSContext.Fork() called after destroy") + } f.cwd.IncRef() f.root.IncRef() } @@ -140,8 +141,8 @@ func (f *FSContext) Fork() *FSContext { // WorkingDirectory returns the current working directory. // -// This will return nil if called after destroy(), otherwise it will return a -// Dirent with a reference taken. +// This will return nil if called after f is destroyed, otherwise it will return +// a Dirent with a reference taken. func (f *FSContext) WorkingDirectory() *fs.Dirent { f.mu.Lock() defer f.mu.Unlock() @@ -152,8 +153,8 @@ func (f *FSContext) WorkingDirectory() *fs.Dirent { // WorkingDirectoryVFS2 returns the current working directory. // -// This will return nil if called after destroy(), otherwise it will return a -// Dirent with a reference taken. +// This will return nil if called after f is destroyed, otherwise it will return +// a Dirent with a reference taken. func (f *FSContext) WorkingDirectoryVFS2() vfs.VirtualDentry { f.mu.Lock() defer f.mu.Unlock() @@ -165,7 +166,7 @@ func (f *FSContext) WorkingDirectoryVFS2() vfs.VirtualDentry { // SetWorkingDirectory sets the current working directory. // This will take an extra reference on the Dirent. // -// This is not a valid call after destroy. +// This is not a valid call after f is destroyed. func (f *FSContext) SetWorkingDirectory(ctx context.Context, d *fs.Dirent) { if d == nil { panic("FSContext.SetWorkingDirectory called with nil dirent") @@ -187,11 +188,15 @@ func (f *FSContext) SetWorkingDirectory(ctx context.Context, d *fs.Dirent) { // SetWorkingDirectoryVFS2 sets the current working directory. // This will take an extra reference on the VirtualDentry. // -// This is not a valid call after destroy. +// This is not a valid call after f is destroyed. func (f *FSContext) SetWorkingDirectoryVFS2(ctx context.Context, d vfs.VirtualDentry) { f.mu.Lock() defer f.mu.Unlock() + if !f.cwdVFS2.Ok() { + panic(fmt.Sprintf("FSContext.SetWorkingDirectoryVFS2(%v)) called after destroy", d)) + } + old := f.cwdVFS2 f.cwdVFS2 = d d.IncRef() @@ -200,8 +205,8 @@ func (f *FSContext) SetWorkingDirectoryVFS2(ctx context.Context, d vfs.VirtualDe // RootDirectory returns the current filesystem root. // -// This will return nil if called after destroy(), otherwise it will return a -// Dirent with a reference taken. +// This will return nil if called after f is destroyed, otherwise it will return +// a Dirent with a reference taken. func (f *FSContext) RootDirectory() *fs.Dirent { f.mu.Lock() defer f.mu.Unlock() @@ -213,8 +218,8 @@ func (f *FSContext) RootDirectory() *fs.Dirent { // RootDirectoryVFS2 returns the current filesystem root. // -// This will return nil if called after destroy(), otherwise it will return a -// Dirent with a reference taken. +// This will return nil if called after f is destroyed, otherwise it will return +// a Dirent with a reference taken. func (f *FSContext) RootDirectoryVFS2() vfs.VirtualDentry { f.mu.Lock() defer f.mu.Unlock() @@ -226,7 +231,7 @@ func (f *FSContext) RootDirectoryVFS2() vfs.VirtualDentry { // SetRootDirectory sets the root directory. // This will take an extra reference on the Dirent. // -// This is not a valid call after free. +// This is not a valid call after f is destroyed. func (f *FSContext) SetRootDirectory(ctx context.Context, d *fs.Dirent) { if d == nil { panic("FSContext.SetRootDirectory called with nil dirent") @@ -247,7 +252,7 @@ func (f *FSContext) SetRootDirectory(ctx context.Context, d *fs.Dirent) { // SetRootDirectoryVFS2 sets the root directory. It takes a reference on vd. // -// This is not a valid call after free. +// This is not a valid call after f is destroyed. func (f *FSContext) SetRootDirectoryVFS2(ctx context.Context, vd vfs.VirtualDentry) { if !vd.Ok() { panic("FSContext.SetRootDirectoryVFS2 called with zero-value VirtualDentry") |