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path: root/pkg/sentry/fsimpl/gofer/regular_file.go
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Diffstat (limited to 'pkg/sentry/fsimpl/gofer/regular_file.go')
-rw-r--r--pkg/sentry/fsimpl/gofer/regular_file.go872
1 files changed, 0 insertions, 872 deletions
diff --git a/pkg/sentry/fsimpl/gofer/regular_file.go b/pkg/sentry/fsimpl/gofer/regular_file.go
deleted file mode 100644
index e95209661..000000000
--- a/pkg/sentry/fsimpl/gofer/regular_file.go
+++ /dev/null
@@ -1,872 +0,0 @@
-// 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 gofer
-
-import (
- "fmt"
- "io"
- "math"
- "sync"
- "sync/atomic"
-
- "gvisor.dev/gvisor/pkg/abi/linux"
- "gvisor.dev/gvisor/pkg/context"
- "gvisor.dev/gvisor/pkg/log"
- "gvisor.dev/gvisor/pkg/safemem"
- "gvisor.dev/gvisor/pkg/sentry/fs/fsutil"
- "gvisor.dev/gvisor/pkg/sentry/memmap"
- "gvisor.dev/gvisor/pkg/sentry/pgalloc"
- "gvisor.dev/gvisor/pkg/sentry/platform"
- "gvisor.dev/gvisor/pkg/sentry/usage"
- "gvisor.dev/gvisor/pkg/sentry/vfs"
- "gvisor.dev/gvisor/pkg/syserror"
- "gvisor.dev/gvisor/pkg/usermem"
-)
-
-func (d *dentry) isRegularFile() bool {
- return d.fileType() == linux.S_IFREG
-}
-
-type regularFileFD struct {
- fileDescription
-
- // off is the file offset. off is protected by mu.
- mu sync.Mutex
- off int64
-}
-
-// Release implements vfs.FileDescriptionImpl.Release.
-func (fd *regularFileFD) Release() {
-}
-
-// OnClose implements vfs.FileDescriptionImpl.OnClose.
-func (fd *regularFileFD) OnClose(ctx context.Context) error {
- if !fd.vfsfd.IsWritable() {
- return nil
- }
- // Skip flushing if writes may be buffered by the client, since (as with
- // the VFS1 client) we don't flush buffered writes on close anyway.
- d := fd.dentry()
- if d.fs.opts.interop == InteropModeExclusive {
- return nil
- }
- d.handleMu.RLock()
- defer d.handleMu.RUnlock()
- return d.handle.file.flush(ctx)
-}
-
-// PRead implements vfs.FileDescriptionImpl.PRead.
-func (fd *regularFileFD) PRead(ctx context.Context, dst usermem.IOSequence, offset int64, opts vfs.ReadOptions) (int64, error) {
- if offset < 0 {
- return 0, syserror.EINVAL
- }
- if opts.Flags != 0 {
- return 0, syserror.EOPNOTSUPP
- }
-
- // Check for reading at EOF before calling into MM (but not under
- // InteropModeShared, which makes d.size unreliable).
- d := fd.dentry()
- if d.fs.opts.interop != InteropModeShared && uint64(offset) >= atomic.LoadUint64(&d.size) {
- return 0, io.EOF
- }
-
- if fd.vfsfd.StatusFlags()&linux.O_DIRECT != 0 {
- // Lock d.metadataMu for the rest of the read to prevent d.size from
- // changing.
- d.metadataMu.Lock()
- defer d.metadataMu.Unlock()
- // Write dirty cached pages that will be touched by the read back to
- // the remote file.
- if err := d.writeback(ctx, offset, dst.NumBytes()); err != nil {
- return 0, err
- }
- }
-
- rw := getDentryReadWriter(ctx, d, offset)
- if fd.vfsfd.StatusFlags()&linux.O_DIRECT != 0 {
- // Require the read to go to the remote file.
- rw.direct = true
- }
- n, err := dst.CopyOutFrom(ctx, rw)
- putDentryReadWriter(rw)
- if d.fs.opts.interop != InteropModeShared {
- // Compare Linux's mm/filemap.c:do_generic_file_read() => file_accessed().
- d.touchAtime(ctx, fd.vfsfd.Mount())
- }
- return n, err
-}
-
-// Read implements vfs.FileDescriptionImpl.Read.
-func (fd *regularFileFD) Read(ctx context.Context, dst usermem.IOSequence, opts vfs.ReadOptions) (int64, error) {
- fd.mu.Lock()
- n, err := fd.PRead(ctx, dst, fd.off, opts)
- fd.off += n
- fd.mu.Unlock()
- return n, err
-}
-
-// PWrite implements vfs.FileDescriptionImpl.PWrite.
-func (fd *regularFileFD) PWrite(ctx context.Context, src usermem.IOSequence, offset int64, opts vfs.WriteOptions) (int64, error) {
- if offset < 0 {
- return 0, syserror.EINVAL
- }
- if opts.Flags != 0 {
- return 0, syserror.EOPNOTSUPP
- }
-
- d := fd.dentry()
- d.metadataMu.Lock()
- defer d.metadataMu.Unlock()
- if d.fs.opts.interop != InteropModeShared {
- // Compare Linux's mm/filemap.c:__generic_file_write_iter() =>
- // file_update_time(). This is d.touchCMtime(), but without locking
- // d.metadataMu (recursively).
- if now, ok := nowFromContext(ctx); ok {
- atomic.StoreInt64(&d.mtime, now)
- atomic.StoreInt64(&d.ctime, now)
- }
- }
- if fd.vfsfd.StatusFlags()&linux.O_DIRECT != 0 {
- // Write dirty cached pages that will be touched by the write back to
- // the remote file.
- if err := d.writeback(ctx, offset, src.NumBytes()); err != nil {
- return 0, err
- }
- // Remove touched pages from the cache.
- pgstart := pageRoundDown(uint64(offset))
- pgend := pageRoundUp(uint64(offset + src.NumBytes()))
- if pgend < pgstart {
- return 0, syserror.EINVAL
- }
- mr := memmap.MappableRange{pgstart, pgend}
- var freed []platform.FileRange
- d.dataMu.Lock()
- cseg := d.cache.LowerBoundSegment(mr.Start)
- for cseg.Ok() && cseg.Start() < mr.End {
- cseg = d.cache.Isolate(cseg, mr)
- freed = append(freed, platform.FileRange{cseg.Value(), cseg.Value() + cseg.Range().Length()})
- cseg = d.cache.Remove(cseg).NextSegment()
- }
- d.dataMu.Unlock()
- // Invalidate mappings of removed pages.
- d.mapsMu.Lock()
- d.mappings.Invalidate(mr, memmap.InvalidateOpts{})
- d.mapsMu.Unlock()
- // Finally free pages removed from the cache.
- mf := d.fs.mfp.MemoryFile()
- for _, freedFR := range freed {
- mf.DecRef(freedFR)
- }
- }
- rw := getDentryReadWriter(ctx, d, offset)
- if fd.vfsfd.StatusFlags()&linux.O_DIRECT != 0 {
- // Require the write to go to the remote file.
- rw.direct = true
- }
- n, err := src.CopyInTo(ctx, rw)
- putDentryReadWriter(rw)
- if n != 0 && fd.vfsfd.StatusFlags()&(linux.O_DSYNC|linux.O_SYNC) != 0 {
- // Write dirty cached pages touched by the write back to the remote
- // file.
- if err := d.writeback(ctx, offset, src.NumBytes()); err != nil {
- return 0, err
- }
- // Request the remote filesystem to sync the remote file.
- if err := d.handle.file.fsync(ctx); err != nil {
- return 0, err
- }
- }
- return n, err
-}
-
-// Write implements vfs.FileDescriptionImpl.Write.
-func (fd *regularFileFD) Write(ctx context.Context, src usermem.IOSequence, opts vfs.WriteOptions) (int64, error) {
- fd.mu.Lock()
- n, err := fd.PWrite(ctx, src, fd.off, opts)
- fd.off += n
- fd.mu.Unlock()
- return n, err
-}
-
-type dentryReadWriter struct {
- ctx context.Context
- d *dentry
- off uint64
- direct bool
-}
-
-var dentryReadWriterPool = sync.Pool{
- New: func() interface{} {
- return &dentryReadWriter{}
- },
-}
-
-func getDentryReadWriter(ctx context.Context, d *dentry, offset int64) *dentryReadWriter {
- rw := dentryReadWriterPool.Get().(*dentryReadWriter)
- rw.ctx = ctx
- rw.d = d
- rw.off = uint64(offset)
- rw.direct = false
- return rw
-}
-
-func putDentryReadWriter(rw *dentryReadWriter) {
- rw.ctx = nil
- rw.d = nil
- dentryReadWriterPool.Put(rw)
-}
-
-// ReadToBlocks implements safemem.Reader.ReadToBlocks.
-func (rw *dentryReadWriter) ReadToBlocks(dsts safemem.BlockSeq) (uint64, error) {
- if dsts.IsEmpty() {
- return 0, nil
- }
-
- // If we have a mmappable host FD (which must be used here to ensure
- // coherence with memory-mapped I/O), or if InteropModeShared is in effect
- // (which prevents us from caching file contents and makes dentry.size
- // unreliable), or if the file was opened O_DIRECT, read directly from
- // dentry.handle without locking dentry.dataMu.
- rw.d.handleMu.RLock()
- if (rw.d.handle.fd >= 0 && !rw.d.fs.opts.forcePageCache) || rw.d.fs.opts.interop == InteropModeShared || rw.direct {
- n, err := rw.d.handle.readToBlocksAt(rw.ctx, dsts, rw.off)
- rw.d.handleMu.RUnlock()
- rw.off += n
- return n, err
- }
-
- // Otherwise read from/through the cache.
- mf := rw.d.fs.mfp.MemoryFile()
- fillCache := mf.ShouldCacheEvictable()
- var dataMuUnlock func()
- if fillCache {
- rw.d.dataMu.Lock()
- dataMuUnlock = rw.d.dataMu.Unlock
- } else {
- rw.d.dataMu.RLock()
- dataMuUnlock = rw.d.dataMu.RUnlock
- }
-
- // Compute the range to read (limited by file size and overflow-checked).
- if rw.off >= rw.d.size {
- dataMuUnlock()
- rw.d.handleMu.RUnlock()
- return 0, io.EOF
- }
- end := rw.d.size
- if rend := rw.off + dsts.NumBytes(); rend > rw.off && rend < end {
- end = rend
- }
-
- var done uint64
- seg, gap := rw.d.cache.Find(rw.off)
- for rw.off < end {
- mr := memmap.MappableRange{rw.off, end}
- switch {
- case seg.Ok():
- // Get internal mappings from the cache.
- ims, err := mf.MapInternal(seg.FileRangeOf(seg.Range().Intersect(mr)), usermem.Read)
- if err != nil {
- dataMuUnlock()
- rw.d.handleMu.RUnlock()
- return done, err
- }
-
- // Copy from internal mappings.
- n, err := safemem.CopySeq(dsts, ims)
- done += n
- rw.off += n
- dsts = dsts.DropFirst64(n)
- if err != nil {
- dataMuUnlock()
- rw.d.handleMu.RUnlock()
- return done, err
- }
-
- // Continue.
- seg, gap = seg.NextNonEmpty()
-
- case gap.Ok():
- gapMR := gap.Range().Intersect(mr)
- if fillCache {
- // Read into the cache, then re-enter the loop to read from the
- // cache.
- reqMR := memmap.MappableRange{
- Start: pageRoundDown(gapMR.Start),
- End: pageRoundUp(gapMR.End),
- }
- optMR := gap.Range()
- err := rw.d.cache.Fill(rw.ctx, reqMR, maxFillRange(reqMR, optMR), mf, usage.PageCache, rw.d.handle.readToBlocksAt)
- mf.MarkEvictable(rw.d, pgalloc.EvictableRange{optMR.Start, optMR.End})
- seg, gap = rw.d.cache.Find(rw.off)
- if !seg.Ok() {
- dataMuUnlock()
- rw.d.handleMu.RUnlock()
- return done, err
- }
- // err might have occurred in part of gap.Range() outside
- // gapMR. Forget about it for now; if the error matters and
- // persists, we'll run into it again in a later iteration of
- // this loop.
- } else {
- // Read directly from the file.
- gapDsts := dsts.TakeFirst64(gapMR.Length())
- n, err := rw.d.handle.readToBlocksAt(rw.ctx, gapDsts, gapMR.Start)
- done += n
- rw.off += n
- dsts = dsts.DropFirst64(n)
- // Partial reads are fine. But we must stop reading.
- if n != gapDsts.NumBytes() || err != nil {
- dataMuUnlock()
- rw.d.handleMu.RUnlock()
- return done, err
- }
-
- // Continue.
- seg, gap = gap.NextSegment(), fsutil.FileRangeGapIterator{}
- }
- }
- }
- dataMuUnlock()
- rw.d.handleMu.RUnlock()
- return done, nil
-}
-
-// WriteFromBlocks implements safemem.Writer.WriteFromBlocks.
-//
-// Preconditions: rw.d.metadataMu must be locked.
-func (rw *dentryReadWriter) WriteFromBlocks(srcs safemem.BlockSeq) (uint64, error) {
- if srcs.IsEmpty() {
- return 0, nil
- }
-
- // If we have a mmappable host FD (which must be used here to ensure
- // coherence with memory-mapped I/O), or if InteropModeShared is in effect
- // (which prevents us from caching file contents), or if the file was
- // opened with O_DIRECT, write directly to dentry.handle without locking
- // dentry.dataMu.
- rw.d.handleMu.RLock()
- if (rw.d.handle.fd >= 0 && !rw.d.fs.opts.forcePageCache) || rw.d.fs.opts.interop == InteropModeShared || rw.direct {
- n, err := rw.d.handle.writeFromBlocksAt(rw.ctx, srcs, rw.off)
- rw.off += n
- rw.d.dataMu.Lock()
- if rw.off > rw.d.size {
- atomic.StoreUint64(&rw.d.size, rw.off)
- // The remote file's size will implicitly be extended to the correct
- // value when we write back to it.
- }
- rw.d.dataMu.Unlock()
- rw.d.handleMu.RUnlock()
- return n, err
- }
-
- // Otherwise write to/through the cache.
- mf := rw.d.fs.mfp.MemoryFile()
- rw.d.dataMu.Lock()
-
- // Compute the range to write (overflow-checked).
- start := rw.off
- end := rw.off + srcs.NumBytes()
- if end <= rw.off {
- end = math.MaxInt64
- }
-
- var (
- done uint64
- retErr error
- )
- seg, gap := rw.d.cache.Find(rw.off)
- for rw.off < end {
- mr := memmap.MappableRange{rw.off, end}
- switch {
- case seg.Ok():
- // Get internal mappings from the cache.
- segMR := seg.Range().Intersect(mr)
- ims, err := mf.MapInternal(seg.FileRangeOf(segMR), usermem.Write)
- if err != nil {
- retErr = err
- goto exitLoop
- }
-
- // Copy to internal mappings.
- n, err := safemem.CopySeq(ims, srcs)
- done += n
- rw.off += n
- srcs = srcs.DropFirst64(n)
- rw.d.dirty.MarkDirty(segMR)
- if err != nil {
- retErr = err
- goto exitLoop
- }
-
- // Continue.
- seg, gap = seg.NextNonEmpty()
-
- case gap.Ok():
- // Write directly to the file. At present, we never fill the cache
- // when writing, since doing so can convert small writes into
- // inefficient read-modify-write cycles, and we have no mechanism
- // for detecting or avoiding this.
- gapMR := gap.Range().Intersect(mr)
- gapSrcs := srcs.TakeFirst64(gapMR.Length())
- n, err := rw.d.handle.writeFromBlocksAt(rw.ctx, gapSrcs, gapMR.Start)
- done += n
- rw.off += n
- srcs = srcs.DropFirst64(n)
- // Partial writes are fine. But we must stop writing.
- if n != gapSrcs.NumBytes() || err != nil {
- retErr = err
- goto exitLoop
- }
-
- // Continue.
- seg, gap = gap.NextSegment(), fsutil.FileRangeGapIterator{}
- }
- }
-exitLoop:
- if rw.off > rw.d.size {
- atomic.StoreUint64(&rw.d.size, rw.off)
- // The remote file's size will implicitly be extended to the correct
- // value when we write back to it.
- }
- // If InteropModeWritethrough is in effect, flush written data back to the
- // remote filesystem.
- if rw.d.fs.opts.interop == InteropModeWritethrough && done != 0 {
- if err := fsutil.SyncDirty(rw.ctx, memmap.MappableRange{
- Start: start,
- End: rw.off,
- }, &rw.d.cache, &rw.d.dirty, rw.d.size, mf, rw.d.handle.writeFromBlocksAt); err != nil {
- // We have no idea how many bytes were actually flushed.
- rw.off = start
- done = 0
- retErr = err
- }
- }
- rw.d.dataMu.Unlock()
- rw.d.handleMu.RUnlock()
- return done, retErr
-}
-
-func (d *dentry) writeback(ctx context.Context, offset, size int64) error {
- if size == 0 {
- return nil
- }
- d.handleMu.RLock()
- defer d.handleMu.RUnlock()
- d.dataMu.Lock()
- defer d.dataMu.Unlock()
- // Compute the range of valid bytes (overflow-checked).
- if uint64(offset) >= d.size {
- return nil
- }
- end := int64(d.size)
- if rend := offset + size; rend > offset && rend < end {
- end = rend
- }
- return fsutil.SyncDirty(ctx, memmap.MappableRange{
- Start: uint64(offset),
- End: uint64(end),
- }, &d.cache, &d.dirty, d.size, d.fs.mfp.MemoryFile(), d.handle.writeFromBlocksAt)
-}
-
-// Seek implements vfs.FileDescriptionImpl.Seek.
-func (fd *regularFileFD) Seek(ctx context.Context, offset int64, whence int32) (int64, error) {
- fd.mu.Lock()
- defer fd.mu.Unlock()
- switch whence {
- case linux.SEEK_SET:
- // Use offset as specified.
- case linux.SEEK_CUR:
- offset += fd.off
- case linux.SEEK_END, linux.SEEK_DATA, linux.SEEK_HOLE:
- // Ensure file size is up to date.
- d := fd.dentry()
- if fd.filesystem().opts.interop == InteropModeShared {
- if err := d.updateFromGetattr(ctx); err != nil {
- return 0, err
- }
- }
- size := int64(atomic.LoadUint64(&d.size))
- // For SEEK_DATA and SEEK_HOLE, treat the file as a single contiguous
- // block of data.
- switch whence {
- case linux.SEEK_END:
- offset += size
- case linux.SEEK_DATA:
- if offset > size {
- return 0, syserror.ENXIO
- }
- // Use offset as specified.
- case linux.SEEK_HOLE:
- if offset > size {
- return 0, syserror.ENXIO
- }
- offset = size
- }
- default:
- return 0, syserror.EINVAL
- }
- if offset < 0 {
- return 0, syserror.EINVAL
- }
- fd.off = offset
- return offset, nil
-}
-
-// Sync implements vfs.FileDescriptionImpl.Sync.
-func (fd *regularFileFD) Sync(ctx context.Context) error {
- return fd.dentry().syncSharedHandle(ctx)
-}
-
-func (d *dentry) syncSharedHandle(ctx context.Context) error {
- d.handleMu.RLock()
- if !d.handleWritable {
- d.handleMu.RUnlock()
- return nil
- }
- d.dataMu.Lock()
- // Write dirty cached data to the remote file.
- err := fsutil.SyncDirtyAll(ctx, &d.cache, &d.dirty, d.size, d.fs.mfp.MemoryFile(), d.handle.writeFromBlocksAt)
- d.dataMu.Unlock()
- if err == nil {
- // Sync the remote file.
- err = d.handle.sync(ctx)
- }
- d.handleMu.RUnlock()
- return err
-}
-
-// ConfigureMMap implements vfs.FileDescriptionImpl.ConfigureMMap.
-func (fd *regularFileFD) ConfigureMMap(ctx context.Context, opts *memmap.MMapOpts) error {
- d := fd.dentry()
- switch d.fs.opts.interop {
- case InteropModeExclusive:
- // Any mapping is fine.
- case InteropModeWritethrough:
- // Shared writable mappings require a host FD, since otherwise we can't
- // synchronously flush memory-mapped writes to the remote file.
- if opts.Private || !opts.MaxPerms.Write {
- break
- }
- fallthrough
- case InteropModeShared:
- // All mappings require a host FD to be coherent with other filesystem
- // users.
- if d.fs.opts.forcePageCache {
- // Whether or not we have a host FD, we're not allowed to use it.
- return syserror.ENODEV
- }
- d.handleMu.RLock()
- haveFD := d.handle.fd >= 0
- d.handleMu.RUnlock()
- if !haveFD {
- return syserror.ENODEV
- }
- default:
- panic(fmt.Sprintf("unknown InteropMode %v", d.fs.opts.interop))
- }
- // After this point, d may be used as a memmap.Mappable.
- d.pf.hostFileMapperInitOnce.Do(d.pf.hostFileMapper.Init)
- return vfs.GenericConfigureMMap(&fd.vfsfd, d, opts)
-}
-
-func (d *dentry) mayCachePages() bool {
- if d.fs.opts.interop == InteropModeShared {
- return false
- }
- if d.fs.opts.forcePageCache {
- return true
- }
- d.handleMu.RLock()
- haveFD := d.handle.fd >= 0
- d.handleMu.RUnlock()
- return haveFD
-}
-
-// AddMapping implements memmap.Mappable.AddMapping.
-func (d *dentry) AddMapping(ctx context.Context, ms memmap.MappingSpace, ar usermem.AddrRange, offset uint64, writable bool) error {
- d.mapsMu.Lock()
- mapped := d.mappings.AddMapping(ms, ar, offset, writable)
- // Do this unconditionally since whether we have a host FD can change
- // across save/restore.
- for _, r := range mapped {
- d.pf.hostFileMapper.IncRefOn(r)
- }
- if d.mayCachePages() {
- // d.Evict() will refuse to evict memory-mapped pages, so tell the
- // MemoryFile to not bother trying.
- mf := d.fs.mfp.MemoryFile()
- for _, r := range mapped {
- mf.MarkUnevictable(d, pgalloc.EvictableRange{r.Start, r.End})
- }
- }
- d.mapsMu.Unlock()
- return nil
-}
-
-// RemoveMapping implements memmap.Mappable.RemoveMapping.
-func (d *dentry) RemoveMapping(ctx context.Context, ms memmap.MappingSpace, ar usermem.AddrRange, offset uint64, writable bool) {
- d.mapsMu.Lock()
- unmapped := d.mappings.RemoveMapping(ms, ar, offset, writable)
- for _, r := range unmapped {
- d.pf.hostFileMapper.DecRefOn(r)
- }
- if d.mayCachePages() {
- // Pages that are no longer referenced by any application memory
- // mappings are now considered unused; allow MemoryFile to evict them
- // when necessary.
- mf := d.fs.mfp.MemoryFile()
- d.dataMu.Lock()
- for _, r := range unmapped {
- // Since these pages are no longer mapped, they are no longer
- // concurrently dirtyable by a writable memory mapping.
- d.dirty.AllowClean(r)
- mf.MarkEvictable(d, pgalloc.EvictableRange{r.Start, r.End})
- }
- d.dataMu.Unlock()
- }
- d.mapsMu.Unlock()
-}
-
-// CopyMapping implements memmap.Mappable.CopyMapping.
-func (d *dentry) CopyMapping(ctx context.Context, ms memmap.MappingSpace, srcAR, dstAR usermem.AddrRange, offset uint64, writable bool) error {
- return d.AddMapping(ctx, ms, dstAR, offset, writable)
-}
-
-// Translate implements memmap.Mappable.Translate.
-func (d *dentry) Translate(ctx context.Context, required, optional memmap.MappableRange, at usermem.AccessType) ([]memmap.Translation, error) {
- d.handleMu.RLock()
- if d.handle.fd >= 0 && !d.fs.opts.forcePageCache {
- d.handleMu.RUnlock()
- mr := optional
- if d.fs.opts.limitHostFDTranslation {
- mr = maxFillRange(required, optional)
- }
- return []memmap.Translation{
- {
- Source: mr,
- File: &d.pf,
- Offset: mr.Start,
- Perms: usermem.AnyAccess,
- },
- }, nil
- }
-
- d.dataMu.Lock()
-
- // Constrain translations to d.size (rounded up) to prevent translation to
- // pages that may be concurrently truncated.
- pgend := pageRoundUp(d.size)
- var beyondEOF bool
- if required.End > pgend {
- if required.Start >= pgend {
- d.dataMu.Unlock()
- d.handleMu.RUnlock()
- return nil, &memmap.BusError{io.EOF}
- }
- beyondEOF = true
- required.End = pgend
- }
- if optional.End > pgend {
- optional.End = pgend
- }
-
- mf := d.fs.mfp.MemoryFile()
- cerr := d.cache.Fill(ctx, required, maxFillRange(required, optional), mf, usage.PageCache, d.handle.readToBlocksAt)
-
- var ts []memmap.Translation
- var translatedEnd uint64
- for seg := d.cache.FindSegment(required.Start); seg.Ok() && seg.Start() < required.End; seg, _ = seg.NextNonEmpty() {
- segMR := seg.Range().Intersect(optional)
- // TODO(jamieliu): Make Translations writable even if writability is
- // not required if already kept-dirty by another writable translation.
- perms := usermem.AccessType{
- Read: true,
- Execute: true,
- }
- if at.Write {
- // From this point forward, this memory can be dirtied through the
- // mapping at any time.
- d.dirty.KeepDirty(segMR)
- perms.Write = true
- }
- ts = append(ts, memmap.Translation{
- Source: segMR,
- File: mf,
- Offset: seg.FileRangeOf(segMR).Start,
- Perms: perms,
- })
- translatedEnd = segMR.End
- }
-
- d.dataMu.Unlock()
- d.handleMu.RUnlock()
-
- // Don't return the error returned by c.cache.Fill if it occurred outside
- // of required.
- if translatedEnd < required.End && cerr != nil {
- return ts, &memmap.BusError{cerr}
- }
- if beyondEOF {
- return ts, &memmap.BusError{io.EOF}
- }
- return ts, nil
-}
-
-func maxFillRange(required, optional memmap.MappableRange) memmap.MappableRange {
- const maxReadahead = 64 << 10 // 64 KB, chosen arbitrarily
- if required.Length() >= maxReadahead {
- return required
- }
- if optional.Length() <= maxReadahead {
- return optional
- }
- optional.Start = required.Start
- if optional.Length() <= maxReadahead {
- return optional
- }
- optional.End = optional.Start + maxReadahead
- return optional
-}
-
-// InvalidateUnsavable implements memmap.Mappable.InvalidateUnsavable.
-func (d *dentry) InvalidateUnsavable(ctx context.Context) error {
- // Whether we have a host fd (and consequently what platform.File is
- // mapped) can change across save/restore, so invalidate all translations
- // unconditionally.
- d.mapsMu.Lock()
- defer d.mapsMu.Unlock()
- d.mappings.InvalidateAll(memmap.InvalidateOpts{})
-
- // Write the cache's contents back to the remote file so that if we have a
- // host fd after restore, the remote file's contents are coherent.
- mf := d.fs.mfp.MemoryFile()
- d.dataMu.Lock()
- defer d.dataMu.Unlock()
- if err := fsutil.SyncDirtyAll(ctx, &d.cache, &d.dirty, d.size, mf, d.handle.writeFromBlocksAt); err != nil {
- return err
- }
-
- // Discard the cache so that it's not stored in saved state. This is safe
- // because per InvalidateUnsavable invariants, no new translations can have
- // been returned after we invalidated all existing translations above.
- d.cache.DropAll(mf)
- d.dirty.RemoveAll()
-
- return nil
-}
-
-// Evict implements pgalloc.EvictableMemoryUser.Evict.
-func (d *dentry) Evict(ctx context.Context, er pgalloc.EvictableRange) {
- d.mapsMu.Lock()
- defer d.mapsMu.Unlock()
- d.dataMu.Lock()
- defer d.dataMu.Unlock()
-
- mr := memmap.MappableRange{er.Start, er.End}
- mf := d.fs.mfp.MemoryFile()
- // Only allow pages that are no longer memory-mapped to be evicted.
- for mgap := d.mappings.LowerBoundGap(mr.Start); mgap.Ok() && mgap.Start() < mr.End; mgap = mgap.NextGap() {
- mgapMR := mgap.Range().Intersect(mr)
- if mgapMR.Length() == 0 {
- continue
- }
- if err := fsutil.SyncDirty(ctx, mgapMR, &d.cache, &d.dirty, d.size, mf, d.handle.writeFromBlocksAt); err != nil {
- log.Warningf("Failed to writeback cached data %v: %v", mgapMR, err)
- }
- d.cache.Drop(mgapMR, mf)
- d.dirty.KeepClean(mgapMR)
- }
-}
-
-// dentryPlatformFile implements platform.File. It exists solely because dentry
-// cannot implement both vfs.DentryImpl.IncRef and platform.File.IncRef.
-//
-// dentryPlatformFile is only used when a host FD representing the remote file
-// is available (i.e. dentry.handle.fd >= 0), and that FD is used for
-// application memory mappings (i.e. !filesystem.opts.forcePageCache).
-type dentryPlatformFile struct {
- *dentry
-
- // fdRefs counts references on platform.File offsets. fdRefs is protected
- // by dentry.dataMu.
- fdRefs fsutil.FrameRefSet
-
- // If this dentry represents a regular file, and handle.fd >= 0,
- // hostFileMapper caches mappings of handle.fd.
- hostFileMapper fsutil.HostFileMapper
-
- // hostFileMapperInitOnce is used to lazily initialize hostFileMapper.
- hostFileMapperInitOnce sync.Once
-}
-
-// IncRef implements platform.File.IncRef.
-func (d *dentryPlatformFile) IncRef(fr platform.FileRange) {
- d.dataMu.Lock()
- seg, gap := d.fdRefs.Find(fr.Start)
- for {
- switch {
- case seg.Ok() && seg.Start() < fr.End:
- seg = d.fdRefs.Isolate(seg, fr)
- seg.SetValue(seg.Value() + 1)
- seg, gap = seg.NextNonEmpty()
- case gap.Ok() && gap.Start() < fr.End:
- newRange := gap.Range().Intersect(fr)
- usage.MemoryAccounting.Inc(newRange.Length(), usage.Mapped)
- seg, gap = d.fdRefs.InsertWithoutMerging(gap, newRange, 1).NextNonEmpty()
- default:
- d.fdRefs.MergeAdjacent(fr)
- d.dataMu.Unlock()
- return
- }
- }
-}
-
-// DecRef implements platform.File.DecRef.
-func (d *dentryPlatformFile) DecRef(fr platform.FileRange) {
- d.dataMu.Lock()
- seg := d.fdRefs.FindSegment(fr.Start)
-
- for seg.Ok() && seg.Start() < fr.End {
- seg = d.fdRefs.Isolate(seg, fr)
- if old := seg.Value(); old == 1 {
- usage.MemoryAccounting.Dec(seg.Range().Length(), usage.Mapped)
- seg = d.fdRefs.Remove(seg).NextSegment()
- } else {
- seg.SetValue(old - 1)
- seg = seg.NextSegment()
- }
- }
- d.fdRefs.MergeAdjacent(fr)
- d.dataMu.Unlock()
-
-}
-
-// MapInternal implements platform.File.MapInternal.
-func (d *dentryPlatformFile) MapInternal(fr platform.FileRange, at usermem.AccessType) (safemem.BlockSeq, error) {
- d.handleMu.RLock()
- bs, err := d.hostFileMapper.MapInternal(fr, int(d.handle.fd), at.Write)
- d.handleMu.RUnlock()
- return bs, err
-}
-
-// FD implements platform.File.FD.
-func (d *dentryPlatformFile) FD() int {
- d.handleMu.RLock()
- fd := d.handle.fd
- d.handleMu.RUnlock()
- return int(fd)
-}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-02 03:33:01 +0000