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https://github.com/hanzoai/visor.git
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Ayush RanjanandgVisor bot
6b2855f537
- gofer client: Added an xattr cache on the inode struct. In case the gofer mount being used is exclusive (cachedMetadataAuthoritative() == true), we cache positive and negative xattr queries. - Subsequently, we now hold metadataMu for the entire duration of xattr operations. This is important to avoid stale updates in the xattr cache due to concurrent xattr operations. This is the same approach we take for maintaining other inode metadata in the inode struct. - Added support for setxattr/removexattr/listxattr in runsc/fsgofer and gofer client (when using directfs). Consequently the seccomp filters for sandbox and gofer processes were expanded to allow these syscalls. - Added xattr syscall tests to //test/syscalls/BUILD so they are run on BuildKite on presubmits. (Also fixed up some tests.) A note about performance: The default rootfs configuration for runsc enables rootfs overlay. In that, the gofer mount is an exclusive mount on the lower layer. fsimpl/overlay issues a lot of getxattr calls on the lower layer to check for opaque directory xattr. However, as before, the "trusted" xattr namespace is not supported. So all those calls continue to fail with EOPNOTSUPP. So this should not regress rootfs overlay performance. When using an overlay where gofer is the upper layer or when "userxattr" mount option is in effect, fsimpl/overlay will similarly issue a lot of getxattr calls using the "user" xattr namespace. This will be allowed by checkXattrPermissions(). To optimize the common case where directories are not opaque, we specially track `overlayOpaqueNegative` in `xattrCache`. This avoids a map allocation during xattrCache.addNegative(). Updates #12475 Updates #12828 PiperOrigin-RevId: 915097116
106 lines
2.8 KiB
Go
106 lines
2.8 KiB
Go
// Copyright 2026 The gVisor Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package gofer
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import "slices"
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// xattrOverlayOpaque is the name of the overlayfs opaque xattr. Note that
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// gofer does not support the trusted xattr namespace.
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const xattrOverlayOpaque = "user.overlay.opaque"
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type xattrCache struct {
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// values caches existing extended attributes.
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values map[string]string
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// negatives tracks xattrs known not to exist (linuxerr.ENODATA).
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negatives map[string]struct{}
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// overlayOpaqueNegative tracks if "user.overlay.opaque" is known not to
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// exist (linuxerr.ENODATA). This avoids allocating xattrsNegative map in
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// the common case.
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overlayOpaqueNegative bool
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// list caches the full list of xattr names. If nil, the list is not cached.
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// If non-nil but empty, the cache is authoritatively empty.
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list []string
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}
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func (c *xattrCache) get(name string) (val string, negative bool, found bool) {
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if cachedVal, ok := c.values[name]; ok {
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found = true
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val = cachedVal
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return
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}
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if name == xattrOverlayOpaque && c.overlayOpaqueNegative {
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found = true
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negative = true
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return
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}
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if _, ok := c.negatives[name]; ok {
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found = true
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negative = true
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return
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}
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return
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}
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func (c *xattrCache) add(name string, value string) {
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if c.values == nil {
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c.values = make(map[string]string)
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}
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c.values[name] = value
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if name == xattrOverlayOpaque {
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c.overlayOpaqueNegative = false
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}
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delete(c.negatives, name)
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if c.list != nil {
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if !slices.Contains(c.list, name) {
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c.list = append(c.list, name)
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}
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}
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}
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func (c *xattrCache) addNegative(name string) {
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delete(c.values, name)
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if name == xattrOverlayOpaque {
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c.overlayOpaqueNegative = true
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} else {
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if c.negatives == nil {
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c.negatives = make(map[string]struct{})
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}
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c.negatives[name] = struct{}{}
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}
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if c.list != nil {
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c.list = slices.DeleteFunc(c.list, func(n string) bool { return n == name })
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}
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}
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func (c *xattrCache) getList() ([]string, bool) {
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if c.list == nil {
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return nil, false
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}
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// Return a copy to prevent the caller from modifying the cached list.
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return append([]string(nil), c.list...), true
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}
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func (c *xattrCache) setList(names []string) {
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if len(names) == 0 {
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c.list = []string{}
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} else {
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// Save a copy to prevent the caller from modifying the cached list.
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c.list = append([]string(nil), names...)
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}
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}
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