diff options
Diffstat (limited to 'pkg/sentry')
| -rw-r--r-- | pkg/sentry/fs/ext/BUILD | 1 | ||||
| -rw-r--r-- | pkg/sentry/fs/ext/ext.go | 61 | ||||
| -rw-r--r-- | pkg/sentry/fs/ext/filesystem.go | 137 |
3 files changed, 138 insertions, 61 deletions
diff --git a/pkg/sentry/fs/ext/BUILD b/pkg/sentry/fs/ext/BUILD index e660e545d..2c15875f5 100644 --- a/pkg/sentry/fs/ext/BUILD +++ b/pkg/sentry/fs/ext/BUILD @@ -7,6 +7,7 @@ go_library( srcs = [ "dentry.go", "ext.go", + "filesystem.go", "inode.go", "utils.go", ], diff --git a/pkg/sentry/fs/ext/ext.go b/pkg/sentry/fs/ext/ext.go index 2604169de..10e235fb1 100644 --- a/pkg/sentry/fs/ext/ext.go +++ b/pkg/sentry/fs/ext/ext.go @@ -20,7 +20,6 @@ import ( "fmt" "io" "os" - "sync" "gvisor.dev/gvisor/pkg/abi/linux" "gvisor.dev/gvisor/pkg/sentry/context" @@ -36,48 +35,6 @@ type filesystemType struct{} // Compiles only if filesystemType implements vfs.FilesystemType. var _ vfs.FilesystemType = (*filesystemType)(nil) -// filesystem implements vfs.FilesystemImpl. -type filesystem struct { - // TODO(b/134676337): Remove when all methods have been implemented. - vfs.FilesystemImpl - - vfsfs vfs.Filesystem - - // mu serializes changes to the dentry tree and the usage of the read seeker. - mu sync.Mutex - - // dev is the ReadSeeker for the underlying fs device. It is protected by mu. - // - // The ext filesystems aim to maximize locality, i.e. place all the data - // blocks of a file close together. On a spinning disk, locality reduces the - // amount of movement of the head hence speeding up IO operations. On an SSD - // there are no moving parts but locality increases the size of each transer - // request. Hence, having mutual exclusion on the read seeker while reading a - // file *should* help in achieving the intended performance gains. - // - // Note: This synchronization was not coupled with the ReadSeeker itself - // because we want to synchronize across read/seek operations for the - // performance gains mentioned above. Helps enforcing one-file-at-a-time IO. - dev io.ReadSeeker - - // inodeCache maps absolute inode numbers to the corresponding Inode struct. - // Inodes should be removed from this once their reference count hits 0. - // - // Protected by mu because every addition and removal from this corresponds to - // a change in the dentry tree. - inodeCache map[uint32]*inode - - // sb represents the filesystem superblock. Immutable after initialization. - sb disklayout.SuperBlock - - // bgs represents all the block group descriptors for the filesystem. - // Immutable after initialization. - bgs []disklayout.BlockGroup -} - -// Compiles only if filesystem implements vfs.FilesystemImpl. -var _ vfs.FilesystemImpl = (*filesystem)(nil) - // getDeviceFd returns the read seeker to the underlying device. // Currently there are two ways of mounting an ext(2/3/4) fs: // 1. Specify a mount with our internal special MountType in the OCI spec. @@ -138,21 +95,3 @@ func (fstype filesystemType) NewFilesystem(ctx context.Context, creds *auth.Cred return &fs.vfsfs, &newDentry(rootInode).vfsd, nil } - -// getOrCreateInode gets the inode corresponding to the inode number passed in. -// It creates a new one with the given inode number if one does not exist. -// -// Preconditions: must be holding fs.mu. -func (fs *filesystem) getOrCreateInode(inodeNum uint32) (*inode, error) { - if in, ok := fs.inodeCache[inodeNum]; ok { - return in, nil - } - - in, err := newInode(fs.dev, fs.sb, fs.bgs, inodeNum) - if err != nil { - return nil, err - } - - fs.inodeCache[inodeNum] = in - return in, nil -} diff --git a/pkg/sentry/fs/ext/filesystem.go b/pkg/sentry/fs/ext/filesystem.go new file mode 100644 index 000000000..7150e75a5 --- /dev/null +++ b/pkg/sentry/fs/ext/filesystem.go @@ -0,0 +1,137 @@ +// Copyright 2019 The gVisor Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +package ext + +import ( + "io" + "sync" + + "gvisor.dev/gvisor/pkg/sentry/context" + "gvisor.dev/gvisor/pkg/sentry/fs/ext/disklayout" + "gvisor.dev/gvisor/pkg/sentry/vfs" + "gvisor.dev/gvisor/pkg/syserror" +) + +// filesystem implements vfs.FilesystemImpl. +type filesystem struct { + // TODO(b/134676337): Remove when all methods have been implemented. + vfs.FilesystemImpl + + vfsfs vfs.Filesystem + + // mu serializes changes to the Dentry tree and the usage of the read seeker. + mu sync.Mutex + + // dev is the ReadSeeker for the underlying fs device. It is protected by mu. + // + // The ext filesystems aim to maximize locality, i.e. place all the data + // blocks of a file close together. On a spinning disk, locality reduces the + // amount of movement of the head hence speeding up IO operations. On an SSD + // there are no moving parts but locality increases the size of each transer + // request. Hence, having mutual exclusion on the read seeker while reading a + // file *should* help in achieving the intended performance gains. + // + // Note: This synchronization was not coupled with the ReadSeeker itself + // because we want to synchronize across read/seek operations for the + // performance gains mentioned above. Helps enforcing one-file-at-a-time IO. + dev io.ReadSeeker + + // inodeCache maps absolute inode numbers to the corresponding Inode struct. + // Inodes should be removed from this once their reference count hits 0. + // + // Protected by mu because every addition and removal from this corresponds to + // a change in the dentry tree. + inodeCache map[uint32]*inode + + // sb represents the filesystem superblock. Immutable after initialization. + sb disklayout.SuperBlock + + // bgs represents all the block group descriptors for the filesystem. + // Immutable after initialization. + bgs []disklayout.BlockGroup +} + +// Compiles only if filesystem implements vfs.FilesystemImpl. +var _ vfs.FilesystemImpl = (*filesystem)(nil) + +// getOrCreateInode gets the inode corresponding to the inode number passed in. +// It creates a new one with the given inode number if one does not exist. +// +// Preconditions: must be holding fs.mu. +func (fs *filesystem) getOrCreateInode(inodeNum uint32) (*inode, error) { + if in, ok := fs.inodeCache[inodeNum]; ok { + return in, nil + } + + in, err := newInode(fs.dev, fs.sb, fs.bgs, inodeNum) + if err != nil { + return nil, err + } + + fs.inodeCache[inodeNum] = in + return in, nil +} + +// Release implements vfs.FilesystemImpl.Release. +func (fs *filesystem) Release() { +} + +// Sync implements vfs.FilesystemImpl.Sync. +func (fs *filesystem) Sync(ctx context.Context) error { + // This is a readonly filesystem for now. + return nil +} + +// The vfs.FilesystemImpl functions below return EROFS because their respective +// man pages say that EROFS must be returned if the path resolves to a file on +// a read-only filesystem. + +// TODO(b/134676337): Implement path traversal and return EROFS only if the +// path resolves to a Dentry within ext fs. + +// MkdirAt implements vfs.FilesystemImpl.MkdirAt. +func (fs *filesystem) MkdirAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.MkdirOptions) error { + return syserror.EROFS +} + +// MknodAt implements vfs.FilesystemImpl.MknodAt. +func (fs *filesystem) MknodAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.MknodOptions) error { + return syserror.EROFS +} + +// RenameAt implements vfs.FilesystemImpl.RenameAt. +func (fs *filesystem) RenameAt(ctx context.Context, rp *vfs.ResolvingPath, vd vfs.VirtualDentry, opts vfs.RenameOptions) error { + return syserror.EROFS +} + +// RmdirAt implements vfs.FilesystemImpl.RmdirAt. +func (fs *filesystem) RmdirAt(ctx context.Context, rp *vfs.ResolvingPath) error { + return syserror.EROFS +} + +// SetStatAt implements vfs.FilesystemImpl.SetStatAt. +func (fs *filesystem) SetStatAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.SetStatOptions) error { + return syserror.EROFS +} + +// SymlinkAt implements vfs.FilesystemImpl.SymlinkAt. +func (fs *filesystem) SymlinkAt(ctx context.Context, rp *vfs.ResolvingPath, target string) error { + return syserror.EROFS +} + +// UnlinkAt implements vfs.FilesystemImpl.UnlinkAt. +func (fs *filesystem) UnlinkAt(ctx context.Context, rp *vfs.ResolvingPath) error { + return syserror.EROFS +} |