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This lets us avoid treating a value of 0 as one reference. All references
using the refsvfs2 template must call InitRefs() before the reference is
incremented/decremented, or else a panic will occur. Therefore, it should be
pretty easy to identify missing InitRef calls during testing.
Updates #1486.
PiperOrigin-RevId: 341411151
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Updates #1486.
PiperOrigin-RevId: 339581879
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This PR implements /proc/[pid]/mem for `pkg/sentry/fs` (refer to #2716) and `pkg/sentry/fsimpl`.
@majek
COPYBARA_INTEGRATE_REVIEW=https://github.com/google/gvisor/pull/4060 from lnsp:proc-pid-mem 2caf9021254646f441be618a9bb5528610e44d43
PiperOrigin-RevId: 339369629
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Much like the VFS2 gofer client, kernfs too now caches dentries. The size of the
LRU cache is configurable via mount options.
Have adopted the same reference semantics from gofer client dentry.
Only sysfs and procfs use this LRU cache. The rest of the kernfs users (devpts,
fusefs, host, pipefs, sockfs) still use the no cache approach.
PiperOrigin-RevId: 339139835
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Added the following fields in kernfs.InodeAttr:
- blockSize
- atime
- mtime
- ctime
Also resolved all TODOs for #1193.
Fixes #1193
PiperOrigin-RevId: 338714527
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Our current reference leak checker uses finalizers to verify whether an object
has reached zero references before it is garbage collected. There are multiple
problems with this mechanism, so a rewrite is in order.
With finalizers, there is no way to guarantee that a finalizer will run before
the program exits. When an unreachable object with a finalizer is garbage
collected, its finalizer will be added to a queue and run asynchronously. The
best we can do is run garbage collection upon sandbox exit to make sure that
all finalizers are enqueued.
Furthermore, if there is a chain of finalized objects, e.g. A points to B
points to C, garbage collection needs to run multiple times before all of the
finalizers are enqueued. The first GC run will register the finalizer for A but
not free it. It takes another GC run to free A, at which point B's finalizer
can be registered. As a result, we need to run GC as many times as the length
of the longest such chain to have a somewhat reliable leak checker.
Finally, a cyclical chain of structs pointing to one another will never be
garbage collected if a finalizer is set. This is a well-known issue with Go
finalizers (https://github.com/golang/go/issues/7358). Using leak checking on
filesystem objects that produce cycles will not work and even result in memory
leaks.
The new leak checker stores reference counted objects in a global map when
leak check is enabled and removes them once they are destroyed. At sandbox
exit, any remaining objects in the map are considered as leaked. This provides
a deterministic way of detecting leaks without relying on the complexities of
finalizers and garbage collection.
This approach has several benefits over the former, including:
- Always detects leaks of objects that should be destroyed very close to
sandbox exit. The old checker very rarely detected these leaks, because it
relied on garbage collection to be run in a short window of time.
- Panics if we forgot to enable leak check on a ref-counted object (we will try
to remove it from the map when it is destroyed, but it will never have been
added).
- Can store extra logging information in the map values without adding to the
size of the ref count struct itself. With the size of just an int64, the ref
count object remains compact, meaning frequent operations like IncRef/DecRef
are more cache-efficient.
- Can aggregate leak results in a single report after the sandbox exits.
Instead of having warnings littered in the log, which were
non-deterministically triggered by garbage collection, we can print all
warning messages at once. Note that this could also be a limitation--the
sandbox must exit properly for leaks to be detected.
Some basic benchmarking indicates that this change does not significantly
affect performance when leak checking is enabled, which is understandable
since registering/unregistering is only done once for each filesystem object.
Updates #1486.
PiperOrigin-RevId: 338685972
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This fixes reference leaks related to accidentally forgetting to DecRef()
after calling one or the other.
PiperOrigin-RevId: 336918922
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Singleton filesystem like devpts and devtmpfs have a single filesystem shared
among all mounts, so they acquire a "self-reference" when initialized that
must be released when the entire virtual filesystem is released at sandbox
exit.
PiperOrigin-RevId: 336828852
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This change aims to fix the memory leak issue reported in #3933.
Background:
VFS2 kernfs kept accumulating invalid dentries if those dentries were not
walked on. After substantial consideration of the problem by our team, we
decided to have an LRU cache solution. This change is the first part to that
solution, where we don't cache anything. The LRU cache can be added on top of
this.
What has changed:
- Introduced the concept of an inode tree in kernfs.OrderedChildren.
This is helpful is cases where the lifecycle of an inode is different from
that of a dentry.
- OrderedChildren now deals with initialized inodes instead of initialized
dentries. It now implements Lookup() where it constructs a new dentry
using the inode.
- OrderedChildren holds a ref on all its children inodes. With this change,
now an inode can "outlive" a dentry pointing to it. See comments in
kernfs.OrderedChildren.
- The kernfs dentry tree is solely maintained by kernfs only. Inode
implementations can not modify the dentry tree.
- Dentries that reach ref count 0 are removed from the dentry tree.
- revalidateChildLocked now defer-DecRefs the newly created dentry from
Inode.Lookup(), limiting its life to the current filesystem operation. If
refs are picked on the dentry during the FS op (via an FD or something),
then it will stick around and will be removed when the FD is closed. So there
is essentially _no caching_ for Look()ed up dentries.
- kernfs.DecRef does not have the precondition that fs.mu must be locked.
Fixes #3933
PiperOrigin-RevId: 336768576
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PiperOrigin-RevId: 334478850
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Updates #1663
PiperOrigin-RevId: 333539293
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Update signatures for:
- walkExistingLocked
- checkDeleteLocked
- Inode.Open
Updates #1193
PiperOrigin-RevId: 333163381
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Updates #1193.
PiperOrigin-RevId: 332939026
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PiperOrigin-RevId: 332760843
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As noticed by @ayushr2, the "implements" comments are not
consistent, e.g.
// IterDirents implements kernfs.inodeDynamicLookup.
// Generate implements vfs.DynamicBytesSource.Generate.
This patch improves this by making the comments like this
consistently include the package name (when the interface
and struct are not in the same package) and method name.
Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com>
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Fixes #3316
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PiperOrigin-RevId: 331824411
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Currently the returned offset is an index, and we can't
use it to find the next fd to serialize, because getdents
should iterate correctly despite mutation of fds. Instead,
we can return the next fd to serialize plus 2 (which
accounts for "." and "..") as the offset.
Fixes: #3894
Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com>
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In Linux, FDSize is fs/proc/array.c:task_state() => struct fdtable::max_fds,
which is set to the underlying array's length in fs/file.c:alloc_fdtable().
Follow-up changes:
- Remove FDTable.GetRefs() and FDTable.GetRefsVFS2(), which are unused.
- Reset FDTable.used to 0 during restore, since the subsequent calls to
FDTable.setAll() increment it again, causing its value to be doubled. (After
this CL, FDTable.used is only used to avoid reallocation in FDTable.GetFDs(),
so this fix is not very visible.)
PiperOrigin-RevId: 331588190
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Updates #1487
PiperOrigin-RevId: 330580699
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This mainly involved enabling kernfs' client filesystems to provide a
StatFS implementation.
Fixes #3411, #3515.
PiperOrigin-RevId: 329009864
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This uses the refs_vfs2 template in vfs2 as well as objects common to vfs1 and
vfs2. Note that vfs1-only refcounts are not replaced, since vfs1 will be deleted
soon anyway.
The following structs now use the new tool, with leak check enabled:
devpts:rootInode
fuse:inode
kernfs:Dentry
kernfs:dir
kernfs:readonlyDir
kernfs:StaticDirectory
proc:fdDirInode
proc:fdInfoDirInode
proc:subtasksInode
proc:taskInode
proc:tasksInode
vfs:FileDescription
vfs:MountNamespace
vfs:Filesystem
sys:dir
kernel:FSContext
kernel:ProcessGroup
kernel:Session
shm:Shm
mm:aioMappable
mm:SpecialMappable
transport:queue
And the following use the template, but because they currently are not leak
checked, a TODO is left instead of enabling leak check in this patch:
kernel:FDTable
tun:tunEndpoint
Updates #1486.
PiperOrigin-RevId: 328460377
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- Remove comment about GenericDirectoryFD not being compatible with
dynamic directories. It is currently being used to implement dynamic
directories.
- Try to handle SEEK_END better than setting the offset to
infinity. SEEK_END is poorly defined for dynamic directories
anyways, so at least try make it work correctly for the static
entries.
Updates #1193.
PiperOrigin-RevId: 327890128
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This lets us create "synthetic" mountpoint directories in ReadOnly mounts
during VFS setup.
Also add context.WithMountNamespace, as some filesystems (like overlay) require
a MountNamespace on ctx to handle vfs.Filesystem Operations.
PiperOrigin-RevId: 327874971
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Updates #1035
PiperOrigin-RevId: 327253907
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- Merges aleksej-paschenko's with HEAD
- Adds vfs2 support for ip_forward
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/proc/sys/net/ipv4/tcp_recovery is used to enable RACK loss
recovery in TCP.
PiperOrigin-RevId: 325157807
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context is passed to DecRef() and Release() which is
needed for SO_LINGER implementation.
PiperOrigin-RevId: 324672584
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Fix typos.
PiperOrigin-RevId: 322913282
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To implement stat(2) in FUSE, we have to embed credentials and pid in request
header. The information should be extracted from the context passed to VFS
layer. Therefore `Stat()` signature in `kernfs.Inode` interface should include
context as first argument. Some other fs implementations need to be modified as
well, such as devpts, host, pipefs, and proc.
Fixes #3235
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We were truncating buf using a index relative to the middle of the slice (i.e.
where envv begins), but we need to calculate the index relative to the entire
slice.
Updates #2923.
PiperOrigin-RevId: 319154950
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- Support writing on proc/[pid]/{uid,gid}map
- Return EIO for writing to static files.
Updates #2923.
PiperOrigin-RevId: 318188503
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Make proc/self/fd iteration work properly. Also, the comment on
kernfs.Inode.IterDirents did not accurately reflect how parameters should be
used/were used in kernfs.Inode impls other than fdDir.
Updates #2923.
PiperOrigin-RevId: 317370325
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- Change FileDescriptionImpl Lock/UnlockPOSIX signature to
take {start,length,whence}, so the correct offset can be
calculated in the implementations.
- Create PosixLocker interface to make it possible to share
the same locking code from different implementations.
Closes #1480
PiperOrigin-RevId: 316910286
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LockFD is the generic implementation that can be embedded in
FileDescriptionImpl implementations. Unique lock ID is
maintained in vfs.FileDescription and is created on demand.
Updates #1480
PiperOrigin-RevId: 315604825
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Updates #1197, #1198, #1672
PiperOrigin-RevId: 310432006
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PiperOrigin-RevId: 310179277
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The /proc/net/udp header was missing, and /proc/sys/net was set up as
/proc/sys/net/net. Discovered while trying to run networking tests for VFS2.
PiperOrigin-RevId: 309243758
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PiperOrigin-RevId: 308304793
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- Return ENOENT for /proc/[pid]/task if task is zoombied or terminated
- Allow directory to be Seek() to the end
- Construct synthetic files for /proc/[pid]/ns/*
- Changed GenericDirectoryFD.Init to not register with FileDescription,
otherwise other implementation cannot change behavior.
Updates #1195,1193
PiperOrigin-RevId: 308294649
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- Fix defer operation ordering in kernfs.Filesystem.AccessAt()
- Add AT_NULL entry in proc/pid/auvx
- Fix line padding in /proc/pid/maps
- Fix linux_dirent serialization for getdents(2)
- Remove file creation flags from vfs.FileDescription.statusFlags()
Updates #1193, #1035
PiperOrigin-RevId: 307704159
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This change:
- Drastically simplifies the synchronization model: filesystem structure is
both implementation-defined and implementation-synchronized.
- Allows implementations of vfs.DentryImpl to use implementation-specific
dentry types, reducing casts during path traversal.
- Doesn't require dentries representing non-directory files to waste space on a
map of children.
- Allows dentry revalidation and mount lookup to be correctly ordered (fixed
FIXME in fsimpl/gofer/filesystem.go).
- Removes the need to have two separate maps in gofer.dentry
(dentry.vfsd.children and dentry.negativeChildren) for positive and negative
lookups respectively.
//pkg/sentry/fsimpl/tmpfs/benchmark_test.go:
name old time/op new time/op delta
VFS2TmpfsStat/1-112 172ns ± 4% 165ns ± 3% -4.08% (p=0.002 n=9+9)
VFS2TmpfsStat/2-112 199ns ± 3% 195ns ±10% ~ (p=0.132 n=8+9)
VFS2TmpfsStat/3-112 230ns ± 2% 216ns ± 2% -6.15% (p=0.000 n=8+8)
VFS2TmpfsStat/8-112 390ns ± 2% 358ns ± 4% -8.33% (p=0.000 n=9+8)
VFS2TmpfsStat/64-112 2.20µs ± 3% 2.01µs ± 3% -8.48% (p=0.000 n=10+8)
VFS2TmpfsStat/100-112 3.42µs ± 9% 3.08µs ± 2% -9.82% (p=0.000 n=9+8)
VFS2TmpfsMountStat/1-112 278ns ± 1% 286ns ±15% ~ (p=0.712 n=8+10)
VFS2TmpfsMountStat/2-112 311ns ± 4% 298ns ± 2% -4.27% (p=0.000 n=9+8)
VFS2TmpfsMountStat/3-112 339ns ± 3% 330ns ± 9% ~ (p=0.070 n=8+9)
VFS2TmpfsMountStat/8-112 503ns ± 3% 466ns ± 3% -7.38% (p=0.000 n=8+8)
VFS2TmpfsMountStat/64-112 2.53µs ±16% 2.17µs ± 7% -14.19% (p=0.000 n=10+9)
VFS2TmpfsMountStat/100-112 3.60µs ± 4% 3.30µs ± 8% -8.33% (p=0.001 n=8+9)
Updates #1035
PiperOrigin-RevId: 307655892
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PiperOrigin-RevId: 305807868
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FileDescription references are side-effectual; for example, holding a reference
on the write end of a pipe prevents reads from the read end from returning EOF.
This change is consistent with Linux, but not VFS1; while VFS1 also has this
bug, it's less visible there since VFS1 procfs disables caching.
Updates #1195
PiperOrigin-RevId: 305545099
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Updates #164
PiperOrigin-RevId: 305544029
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This fixes a bug in the proc net directory.
Updates #2243
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Updates #1195
PiperOrigin-RevId: 305143567
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Updates #1476, #1478, #1484, #1485.
PiperOrigin-RevId: 304845354
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Some extra fields were added to the Mount type to expose necessary data to the
proc filesystem.
PiperOrigin-RevId: 304053361
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Both have analogues in Linux:
* struct file_system_type has a char *name field.
* struct super_block keeps a pointer to the file_system_type.
These fields are necessary to support the `filesystem type` field in
/proc/[pid]/mountinfo.
PiperOrigin-RevId: 303434063
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