openedMu has lock ordering violations. Most locks go through OpenedFlag(),
which is usually taken after renameMu and opMu. On the other hand, Tlopen takes
openedMu before renameMu and opMu (via safelyRead).
Resolving this violation is simple: just drop openedMu. The opened and
openFlags fields are already protected by opMu in most cases, renameMu (for
write) in one case (via safelyGlobal), and only in doWalk by neither.
This is a bit ugly because opMu is supposed to be a "semantic" lock, but it
works. I'm open to other suggestions.
Note that doWalk has a race condition where a FID may open after the open check
but before actually walking. This race existed before this change as well; it
is not clear if it is problematic.
PiperOrigin-RevId: 346108483
They were returning io.ErrShortWrite, but that is not handled at higher levels
and resulted in a panic.
We can just return the short write directly from the p9 call without
ErrShortWrite.
PiperOrigin-RevId: 342960441
This is to cover the common pattern: open->read/write->close,
where SetAttr needs to be called to update atime/mtime before
the file is closed.
Benchmark results:
BM_OpenReadClose/10240 CPU
setattr+clunk: 63783 ns
VFS2: 68109 ns
VFS1: 72507 ns
Updates #1198
PiperOrigin-RevId: 329628461
- Remove sendDone, which currently does nothing whatsoever (errors sent to the
channel are completely unused). Instead, have request handlers log errors
they get from p9.send() inline.
- Replace recvOkay and recvDone with recvMu/recvIdle/recvShutdown. In addition
to being slightly clearer (IMO), this eliminates the p9.connState.service()
goroutine, significantly reducing the overhead involved in passing connection
receive access between goroutines (from buffered chan send/recv + unbuffered
chan send/recv to just a mutex unlock/lock).
PiperOrigin-RevId: 327476755
Continues the modifications in cl/272963663. This prevents non-syscall errors
from being propogated to kernel/task_syscall.go:ExtractErrno(), which causes a
sentry panic.
PiperOrigin-RevId: 305913127
There was a very bare get/setxattr in the InodeOperations interface. Add
context.Context to both, size to getxattr, and flags to setxattr.
Note that extended attributes are passed around as strings in this
implementation, so size is automatically encoded into the value. Size is
added in getxattr so that implementations can return ERANGE if a value is larger
than can fit in the user-allocated buffer. This prevents us from unnecessarily
passing around an arbitrarily large xattr when the user buffer is actually too
small.
Don't use the existing xattrwalk and xattrcreate messages and define our
own, mainly for the sake of simplicity.
Extended attributes will be implemented in future commits.
PiperOrigin-RevId: 290121300
* Rename syncutil to sync.
* Add aliases to sync types.
* Replace existing usage of standard library sync package.
This will make it easier to swap out synchronization primitives. For example,
this will allow us to use primitives from github.com/sasha-s/go-deadlock to
check for lock ordering violations.
Updates #1472
PiperOrigin-RevId: 289033387
These comments provided nothing, and have been copy-pasted into all
implementations. The code is clear without them.
I considered also removing the "handle implements handler.handle" comments, but
will let those stay for now.
PiperOrigin-RevId: 285876428
Note that the Sentry still calls Truncate() on the file before calling Open.
A new p9 version check was added to ensure that the p9 server can handle the
the OpenTruncate flag. If not, then the flag is stripped before sending.
PiperOrigin-RevId: 281609112
Aside from the performance hit, there is no guarantee that p9.ClientFile's
finalizer runs before the associated p9.Client is closed.
PiperOrigin-RevId: 280702509
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