Age | Commit message (Collapse) | Author |
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Linux 4.18 and later make reads and writes coherent between pre-copy-up and
post-copy-up FDs representing the same file on an overlay filesystem. However,
memory mappings remain incoherent:
- Documentation/filesystems/overlayfs.rst, "Non-standard behavior": "If a file
residing on a lower layer is opened for read-only and then memory mapped with
MAP_SHARED, then subsequent changes to the file are not reflected in the
memory mapping."
- fs/overlay/file.c:ovl_mmap() passes through to the underlying FD without any
management of coherence in the overlay.
- Experimentally on Linux 5.2:
```
$ cat mmap_cat_page.c
#include <err.h>
#include <fcntl.h>
#include <stdio.h>
#include <string.h>
#include <sys/mman.h>
#include <unistd.h>
int main(int argc, char **argv) {
if (argc < 2) {
errx(1, "syntax: %s [FILE]", argv[0]);
}
const int fd = open(argv[1], O_RDONLY);
if (fd < 0) {
err(1, "open(%s)", argv[1]);
}
const size_t page_size = sysconf(_SC_PAGE_SIZE);
void* page = mmap(NULL, page_size, PROT_READ, MAP_SHARED, fd, 0);
if (page == MAP_FAILED) {
err(1, "mmap");
}
for (;;) {
write(1, page, strnlen(page, page_size));
if (getc(stdin) == EOF) {
break;
}
}
return 0;
}
$ gcc -O2 -o mmap_cat_page mmap_cat_page.c
$ mkdir lowerdir upperdir workdir overlaydir
$ echo old > lowerdir/file
$ sudo mount -t overlay -o "lowerdir=lowerdir,upperdir=upperdir,workdir=workdir" none overlaydir
$ ./mmap_cat_page overlaydir/file
old
^Z
[1]+ Stopped ./mmap_cat_page overlaydir/file
$ echo new > overlaydir/file
$ cat overlaydir/file
new
$ fg
./mmap_cat_page overlaydir/file
old
```
Therefore, while the VFS1 gofer client's behavior of reopening read FDs is only
necessary pre-4.18, replacing existing memory mappings (in both sentry and
application address spaces) with mappings of the new FD is required regardless
of kernel version, and this latter behavior is common to both VFS1 and VFS2.
Re-document accordingly, and change the runsc flag to enabled by default.
New test:
- Before this CL: https://source.cloud.google.com/results/invocations/5b222d2c-e918-4bae-afc4-407f5bac509b
- After this CL: https://source.cloud.google.com/results/invocations/f28c747e-d89c-4d8c-a461-602b33e71aab
PiperOrigin-RevId: 311361267
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Updates #1487
PiperOrigin-RevId: 311356385
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PiperOrigin-RevId: 311234146
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PiperOrigin-RevId: 310963404
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Some code paths needed these syscalls anyways, so they should be included in
the filters. Given that we depend on these syscalls in some cases, there's no
real reason to avoid them any more.
PiperOrigin-RevId: 310829126
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Updates #1197, #1198, #1672
PiperOrigin-RevId: 310432006
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PiperOrigin-RevId: 310417191
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Synthetic sockets do not have the race condition issue in VFS2, and we will
get rid of privateunixsocket as well.
Fixes #1200.
PiperOrigin-RevId: 310386474
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We can register any number of tables with any number of architectures, and
need not limit the definitions to the architecture in question. This allows
runsc to generate documentation for all architectures simultaneously.
Similarly, this simplifies the VFSv2 patching process.
PiperOrigin-RevId: 310224827
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Also added back the default test dimension back which was
dropped in a previous refactor.
PiperOrigin-RevId: 309797327
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PiperOrigin-RevId: 309787938
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Updates #1623, #1487
PiperOrigin-RevId: 309777922
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Updates #231
PiperOrigin-RevId: 309339316
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Updates #231
PiperOrigin-RevId: 309323808
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PiperOrigin-RevId: 309082540
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PiperOrigin-RevId: 308829800
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PiperOrigin-RevId: 308727526
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Previously we unconditionally failed to cleanup the networking files
(hostname, resolve.conf, hosts), and failed to cleanup the netns, etc on
partial setup failure.
We can drop the iptables commands from cleanup, as the routes
automatically go away when the device is deleted. Those commands were
failing previously.
Forward signals to the container, allowing it to exit normally when a
signal is received, and then for runsc to run the cleanup. This doesn't
cover cleanup when runsc is signalled before the container start, it
covers the most common case.
Fixes #2539
Fixes #2540
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Use the sighandling package for Container.ForwardSignals, for
consistency with other signal forwarding.
Fixes #2546
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typo, should be `start` in comments
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Signed-off-by: moricho <ikeda.morito@gmail.com>
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Several tests are passing after getting TestAppExitStatus (run /bin/true)
changes. Make versions that run via VFS2 so that we know what is and isn't
working.
In addition, fix bug in VFSFile ReadFull. For the TestExePath test in
container_test.go, the case "unmasked" will return 0 bytes read with no
EOF err, causing the ReadFull call to spin.
PiperOrigin-RevId: 308428126
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Signed-off-by: moricho <ikeda.morito@gmail.com>
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rbind
Signed-off-by: moricho <ikeda.morito@gmail.com>
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This change includes:
- Modifications to loader_test.go to get TestCreateMountNamespace to
pass with VFS2.
- Changes necessary to get TestHelloWorld in image tests to pass with
VFS2. This means runsc can run the hello-world container with docker
on VSF2.
Note: Containers that use sockets will not run with these changes.
See "//test/image/...". Any tests here with sockets currently fail
(which is all of them but HelloWorld).
PiperOrigin-RevId: 308363072
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Closes #2489
PiperOrigin-RevId: 308362434
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PiperOrigin-RevId: 308304793
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This is needed to set up host fds passed through a Unix socket. Note that
the host package depends on kernel, so we cannot set up the hostfs mount
directly in Kernel.Init as we do for sockfs and pipefs.
Also, adjust sockfs to make its setup look more like hostfs's and pipefs's.
PiperOrigin-RevId: 308274053
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