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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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PiperOrigin-RevId: 339505487
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Inode number consistency checks are now skipped in save/restore tests for
reasons described in greatest detail in StatTest.StateDoesntChangeAfterRename.
They pass in VFS1 due to the bug described in new test case
SimpleStatTest.DifferentFilesHaveDifferentDeviceInodeNumberPairs.
Fixes #1663
PiperOrigin-RevId: 338776148
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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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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 inĀ #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: 334721453
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Updates #1663
PiperOrigin-RevId: 333539293
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There were some instances where we were not enabling leak checking.
PiperOrigin-RevId: 333418571
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Update signatures for:
- walkExistingLocked
- checkDeleteLocked
- Inode.Open
Updates #1193
PiperOrigin-RevId: 333163381
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PiperOrigin-RevId: 332486111
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This change includes overlay, special regular gofer files, and hostfs.
Fixes #3589.
PiperOrigin-RevId: 332330860
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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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PiperOrigin-RevId: 331256608
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Fixes an error where in case of a receive buffer larger than the host send
buffer size for a host backed unix dgram socket we would end up swallowing EOF
from recvmsg syscall causing the read() to block forever.
PiperOrigin-RevId: 331192810
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Updates #2972
PiperOrigin-RevId: 329584905
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FD notifier should be removed before we close the FD,
otherwise there will be race condition that another FD
which has the same value is opened and added before the
existing FD notifier is removed.
Fixes: #3823
Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com>
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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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PiperOrigin-RevId: 328415633
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Includes a minor refactor for inode construction.
Updates #1486.
PiperOrigin-RevId: 327694933
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This interface method is unneeded.
PiperOrigin-RevId: 327370325
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This is needed to avoid circular dependencies between the vfs and kernel
packages.
PiperOrigin-RevId: 327355524
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Fixes #2923
PiperOrigin-RevId: 326296589
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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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The subsequent systrap changes will need to import memmap from
the platform package.
PiperOrigin-RevId: 323409486
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- Check write permission on truncate(2). Unlike ftruncate(2),
truncate(2) fails if the user does not have write permissions
on the file.
- For gofers under InteropModeShared, check file type before
making a truncate request. We should fail early and avoid
making an rpc when possible. Furthermore, depending on the
remote host's failure may give us unexpected behavior--if the
host converts the truncate request to an ftruncate syscall on
an open fd, we will get EINVAL instead of EISDIR.
Updates #2923.
PiperOrigin-RevId: 322913569
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PiperOrigin-RevId: 321496734
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Now it calls pkt.Data.ToView() when writing the packet. This may require
copying when the packet is large, which puts the worse case in an even worse
situation.
This sent out in a separate preparation change as it requires syscall filter
changes. This change will be followed by the change for the adoption of the new
PacketHeader API.
PiperOrigin-RevId: 321447003
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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 do not support RWF_SYNC/RWF_DSYNC and probably shouldn't silently accept
them, since the user may incorrectly believe that we are synchronizing I/O.
Remove the pwritev2 test verifying that we support these flags.
gvisor.dev/issue/2601 is the tracking bug for deciding which RWF_.* flags
we need and supporting them.
Updates #2923, #2601.
PiperOrigin-RevId: 319351286
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Complements cl/315991648.
PiperOrigin-RevId: 319327853
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PiperOrigin-RevId: 319283715
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This CL does a handful of things:
- Support O_DSYNC, O_SYNC
- Support O_APPEND and document an unavoidable race condition
- Ignore O_DIRECT; we probably don't want to allow applications to set O_DIRECT
on the host fd itself.
- Leave a TODO for supporting O_NONBLOCK, which is a simple fix once RWF_NOWAIT
is supported.
- Get rid of caching TODO; force_page_cache is not configurable for host fs in
vfs1 or vfs2 after whitelist fs was removed.
- For the remaining TODOs, link to more specific bugs.
Fixes #1672.
PiperOrigin-RevId: 317985269
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PiperOrigin-RevId: 317796028
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Updates #2972
PiperOrigin-RevId: 317113059
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Updates #1035, #1199
PiperOrigin-RevId: 317028108
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Updates #2972
PiperOrigin-RevId: 316942245
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Simplify the canMap check. We do not have plans to allow mmap for anything
beyond regular files, so we can just inline canMap() as a simple file mode
check.
Updates #1672.
PiperOrigin-RevId: 316929654
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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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PiperOrigin-RevId: 312559861
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In VFS1, both fs/host and fs/gofer used the same utils for host file mappings.
Refactor parts of fsimpl/gofer to create similar utils to share with
fsimpl/host (memory accounting code moved to fsutil, page rounding arithmetic
moved to usermem).
Updates #1476.
PiperOrigin-RevId: 312345090
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PiperOrigin-RevId: 311014995
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This has two effects: It makes flags passed to open("/proc/[pid]/fd/[hostfd]")
effective, and it prevents imported pipes/sockets/character devices from being
opened with O_NONBLOCK unconditionally (because the underlying host FD was set
to non-blocking in ImportFD()).
PiperOrigin-RevId: 310596062
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Updates #1197, #1198, #1672
PiperOrigin-RevId: 310432006
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Implement PrependPath() in host.filesystem to correctly format
name for host files.
Updates #1672
PiperOrigin-RevId: 309959135
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Updates #1623, #1487
PiperOrigin-RevId: 309777922
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All three follow the same pattern:
1. Refactor VFS1 sockets into socketOpsCommon, so that most of the methods can
be shared with VFS2.
2. Create a FileDescriptionImpl with the corresponding socket operations,
rewriting the few that cannot be shared with VFS1.
3. Set up a VFS2 socket provider that creates a socket by setting up a dentry
in the global Kernel.socketMount and connecting it with a new
FileDescription.
This mostly completes the work for porting sockets to VFS2, and many syscall
tests can be enabled as a result.
There are several networking-related syscall tests that are still not passing:
1. net gofer tests
2. socketpair gofer tests
2. sendfile tests (splice is not implemented in VFS2 yet)
Updates #1478, #1484, #1485
PiperOrigin-RevId: 309457331
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This fixes bash in Ubuntu.
Updates #1672.
PiperOrigin-RevId: 309298252
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The FileDescription implementation for hostfs sockets uses the standard Unix
socket implementation (unix.SocketVFS2), but is also tied to a hostfs dentry.
Updates #1672, #1476
PiperOrigin-RevId: 308716426
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