mirror of
https://github.com/netbirdio/gvisor.git
synced 2026-05-22 17:12:49 -07:00
Ayush RanjanandgVisor bot
ab9d8455d4
When using overlayfs with tmpfs as the upper layer (common case), depending on the application, a lot of whiteouts can be created. This leads to a lot of memory allocation because new dentry and inode structs need to be allocated for each whiteout. With this change, we at least avoid the inode allocations. This is analogous with what Linux does. See fs/overlayfs/ovl_entry.h:ovl_fs's field `whiteout` with comment "Shared whiteout cache". PiperOrigin-RevId: 704897805
130 lines
3.3 KiB
Go
130 lines
3.3 KiB
Go
// Copyright 2018 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 linux
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// Filesystem types used in statfs(2).
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//
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// See linux/magic.h.
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const (
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ANON_INODE_FS_MAGIC = 0x09041934
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CGROUP_SUPER_MAGIC = 0x27e0eb
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DEVPTS_SUPER_MAGIC = 0x00001cd1
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EXT_SUPER_MAGIC = 0xef53
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FUSE_SUPER_MAGIC = 0x65735546
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MQUEUE_MAGIC = 0x19800202
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NSFS_MAGIC = 0x6e736673
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OVERLAYFS_SUPER_MAGIC = 0x794c7630
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PIPEFS_MAGIC = 0x50495045
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PROC_SUPER_MAGIC = 0x9fa0
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RAMFS_MAGIC = 0x09041934
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SOCKFS_MAGIC = 0x534F434B
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SYSFS_MAGIC = 0x62656572
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TMPFS_MAGIC = 0x01021994
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V9FS_MAGIC = 0x01021997
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)
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// Filesystem path limits, from uapi/linux/limits.h.
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const (
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NAME_MAX = 255
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PATH_MAX = 4096
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)
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// The bit mask f_flags in struct statfs, from include/linux/statfs.h
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const (
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ST_RDONLY = 0x0001
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ST_NOSUID = 0x0002
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ST_NODEV = 0x0004
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ST_NOEXEC = 0x0008
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ST_SYNCHRONOUS = 0x0010
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ST_VALID = 0x0020
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ST_MANDLOCK = 0x0040
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ST_NOATIME = 0x0400
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ST_NODIRATIME = 0x0800
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ST_RELATIME = 0x1000
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ST_NOSYMFOLLOW = 0x2000
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)
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// Statfs is struct statfs, from uapi/asm-generic/statfs.h.
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//
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// +marshal
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type Statfs struct {
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// Type is one of the filesystem magic values, defined above.
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Type uint64
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// BlockSize is the optimal transfer block size in bytes.
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BlockSize int64
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// Blocks is the maximum number of data blocks the filesystem may store, in
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// units of BlockSize.
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Blocks uint64
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// BlocksFree is the number of free data blocks, in units of BlockSize.
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BlocksFree uint64
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// BlocksAvailable is the number of data blocks free for use by
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// unprivileged users, in units of BlockSize.
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BlocksAvailable uint64
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// Files is the number of used file nodes on the filesystem.
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Files uint64
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// FileFress is the number of free file nodes on the filesystem.
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FilesFree uint64
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// FSID is the filesystem ID.
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FSID [2]int32
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// NameLength is the maximum file name length.
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NameLength uint64
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// FragmentSize is equivalent to BlockSize.
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FragmentSize int64
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// Flags is the set of filesystem mount flags.
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Flags uint64
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// Spare is unused.
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Spare [4]uint64
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}
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// Whence argument to lseek(2), from include/uapi/linux/fs.h.
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const (
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SEEK_SET = 0
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SEEK_CUR = 1
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SEEK_END = 2
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SEEK_DATA = 3
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SEEK_HOLE = 4
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)
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// Sync_file_range flags, from include/uapi/linux/fs.h
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const (
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SYNC_FILE_RANGE_WAIT_BEFORE = 1
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SYNC_FILE_RANGE_WRITE = 2
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SYNC_FILE_RANGE_WAIT_AFTER = 4
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)
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// Flag argument to renameat2(2), from include/uapi/linux/fs.h.
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const (
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RENAME_NOREPLACE = (1 << 0) // Don't overwrite target.
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RENAME_EXCHANGE = (1 << 1) // Exchange src and dst.
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RENAME_WHITEOUT = (1 << 2) // Whiteout src.
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)
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// Overlayfs constants from include/linux/fs.h.
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const (
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WHITEOUT_MODE = 0
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WHITEOUT_DEV = 0
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)
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