When any of these flags are set, all writes will trigger a subsequent fsync
call. This behavior already existed for "write-through" mounts.
O_DIRECT is treated as an alias for O_SYNC. Better support coming soon.
PiperOrigin-RevId: 275114392
Currently, the overlay dirCache is only used for a single logical use of
getdents. i.e., it is discard when the FD is closed or seeked back to
the beginning.
But the initial work of getting the directory contents can be quite
expensive (particularly sorting large directories), so we should keep it
as long as possible.
This is very similar to the readdirCache in fs/gofer.
Since the upper filesystem does not have to allow caching readdir
entries, the new CacheReaddir MountSourceOperations method controls this
behavior.
This caching should be trivially movable to all Inodes if desired,
though that adds an additional copy step for non-overlay Inodes.
(Overlay Inodes already do the extra copy).
PiperOrigin-RevId: 255477592
This does not actually implement an efficient splice or sendfile. Rather, it
adds a generic plumbing to the file internals so that this can be added. All
file implementations use the stub fileutil.NoSplice implementation, which
causes sendfile and splice to fall back to an internal copy.
A basic splice system call interface is added, along with a test.
PiperOrigin-RevId: 249335960
Change-Id: Ic5568be2af0a505c19e7aec66d5af2480ab0939b
Based on the guidelines at
https://opensource.google.com/docs/releasing/authors/.
1. $ rg -l "Google LLC" | xargs sed -i 's/Google LLC.*/The gVisor Authors./'
2. Manual fixup of "Google Inc" references.
3. Add AUTHORS file. Authors may request to be added to this file.
4. Point netstack AUTHORS to gVisor AUTHORS. Drop CONTRIBUTORS.
Fixes#209
PiperOrigin-RevId: 245823212
Change-Id: I64530b24ad021a7d683137459cafc510f5ee1de9
RootFromContext can return a dirent with reference taken, or nil. We must call
DecRef if (and only if) a real dirent is returned.
PiperOrigin-RevId: 242965515
Change-Id: Ie2b7b4cb19ee09b6ccf788b71f3fd7efcdf35a11
This changed required making fsutil.HostMappable use
a backing file to ensure the correct FD would be used
for read/write operations.
RELNOTES: relnotes is needed for the parent CL.
PiperOrigin-RevId: 231836164
Change-Id: I8ae9639715529874ea7d80a65e2c711a5b4ce254
When file size changes outside the sandbox, page cache was not
refreshing file size which is required for cacheRemoteRevalidating.
In fact, cacheRemoteRevalidating should be skipping the cache
completely since it's not really benefiting from it. The cache is
cache is already bypassed for unstable attributes (see
cachePolicy.cacheUAttrs). And althought the cache is called to
map pages, they will always miss the cache and map directly from
the host.
Created a HostMappable struct that maps directly to the host and
use it for files with cacheRemoteRevalidating.
Closes#124
PiperOrigin-RevId: 230998440
Change-Id: Ic5f632eabe33b47241e05e98c95e9b2090ae08fc
More helper structs have been added to the fsutil package to make it easier to
implement fs.InodeOperations and fs.FileOperations.
PiperOrigin-RevId: 229305982
Change-Id: Ib6f8d3862f4216745116857913dbfa351530223b
This CL adds a new cache-policy for gofer filesystems that uses the host page
cache, but causes dirents to be reloaded on each Walk, and does not cache
readdir results.
This policy is useful when the remote filesystem may change out from underneath
us, as any remote changes will be reflected on the next Walk.
Importantly, this cache policy is only consistent if we do not use gVisor's
internal page cache, since that page cache is tied to the Inode and may be
thrown away upon Revalidation.
This cache policy should only be used when the gofer supports donating host
FDs, since then gVisor will make use of the host kernel page cache, which will
be consistent for all open files in the gofer. In fact, a panic will be raised
if a file is opened without a donated FD.
PiperOrigin-RevId: 207752937
Change-Id: I233cb78b4695bbe00a4605ae64080a47629329b8
Dirent.FullName takes the global renameMu, but can be called during Create,
which itself takes dirent.mu and dirent.dirMu, which is a lock-order violation:
Dirent.Create
d.dirMu.Lock
d.mu.Lock
Inode.Create
gofer.inodeOperations.Create
gofer.NewFile
Dirent.FullName
d.renameMu.RLock
We only use the FullName here for logging, and in this case we can get by with
logging only the BaseName.
A `BaseName` method was added to Dirent, which simply returns the name, taking
d.parent.mu as required.
In the Create pathway, we can't call d.BaseName() because taking d.parent.mu
after d.mu violates the lock order. But we already know the base name of the
file we just created, so that's OK.
In the Open/GetFile pathway, we are free to call d.BaseName() because the other
dirent locks are not held.
PiperOrigin-RevId: 205112278
Change-Id: Ib45c734081aecc9b225249a65fa8093eb4995f10
The new policy is identical to FSCACHE (which caches everything in memory), but
it also flushes writes to the backing fs agent immediately.
All gofer cache policy decisions have been moved into the cachePolicy type.
Previously they were sprinkled around the codebase.
There are many different things that we cache (page cache, negative dirents,
dirent LRU, unstable attrs, readdir results....), and I don't think we should
have individual flags to control each of these. Instead, we should have a few
high-level cache policies that are consistent and useful to users. This
refactoring makes it easy to add more such policies.
PiperOrigin-RevId: 201206937
Change-Id: I6e225c382b2e5e1b0ad4ccf8ca229873f4cd389d
Nicolas Lacasse
Michael Pratt
Adin Scannell
Jamie Liu
Googler
Fabricio Voznika
Ian Gudger
Zhaozhong Ni