diff options
| author |   Jens Axboe <axboe@kernel.dk> | 2020-12-17 09:19:10 -0700 |
|---|---|---|
| committer |   Al Viro <viro@zeniv.linux.org.uk> | 2021-01-04 11:42:26 -0500 |
| commit | 99668f618062816ca7ba639b007eb145b9d3d41e (patch) | |
| tree | 71b0b572f7e2b7f9b58a35fbd842c1d39ce3ffd8 | |
| parent | fs: add support for LOOKUP_CACHED (diff) | |
| download | wireguard-linux-99668f618062816ca7ba639b007eb145b9d3d41e.tar.xz wireguard-linux-99668f618062816ca7ba639b007eb145b9d3d41e.zip | |
fs: expose LOOKUP_CACHED through openat2() RESOLVE_CACHED
Now that we support non-blocking path resolution internally, expose it
via openat2() in the struct open_how ->resolve flags. This allows
applications using openat2() to limit path resolution to the extent that
it is already cached.
If the lookup cannot be satisfied in a non-blocking manner, openat2(2)
will return -1/-EAGAIN.
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
| -rw-r--r-- | fs/open.c | 6 | ||||
| -rw-r--r-- | include/linux/fcntl.h | 2 | ||||
| -rw-r--r-- | include/uapi/linux/openat2.h | 4 |
3 files changed, 11 insertions, 1 deletions
diff --git a/fs/open.c b/fs/open.c index 1e06e443a565..ca5444733acd 100644 --- a/fs/open.c +++ b/fs/open.c @@ -1091,6 +1091,12 @@ inline int build_open_flags(const struct open_how *how, struct open_flags *op) lookup_flags |= LOOKUP_BENEATH; if (how->resolve & RESOLVE_IN_ROOT) lookup_flags |= LOOKUP_IN_ROOT; + if (how->resolve & RESOLVE_CACHED) { + /* Don't bother even trying for create/truncate/tmpfile open */ + if (flags & (O_TRUNC | O_CREAT | O_TMPFILE)) + return -EAGAIN; + lookup_flags |= LOOKUP_CACHED; + } op->lookup_flags = lookup_flags; return 0; diff --git a/include/linux/fcntl.h b/include/linux/fcntl.h index 921e750843e6..766fcd973beb 100644 --- a/include/linux/fcntl.h +++ b/include/linux/fcntl.h @@ -19,7 +19,7 @@ /* List of all valid flags for the how->resolve argument: */ #define VALID_RESOLVE_FLAGS \ (RESOLVE_NO_XDEV | RESOLVE_NO_MAGICLINKS | RESOLVE_NO_SYMLINKS | \ - RESOLVE_BENEATH | RESOLVE_IN_ROOT) + RESOLVE_BENEATH | RESOLVE_IN_ROOT | RESOLVE_CACHED) /* List of all open_how "versions". */ #define OPEN_HOW_SIZE_VER0 24 /* sizeof first published struct */ diff --git a/include/uapi/linux/openat2.h b/include/uapi/linux/openat2.h index 58b1eb711360..a5feb7604948 100644 --- a/include/uapi/linux/openat2.h +++ b/include/uapi/linux/openat2.h @@ -35,5 +35,9 @@ struct open_how { #define RESOLVE_IN_ROOT 0x10 /* Make all jumps to "/" and ".." be scoped inside the dirfd (similar to chroot(2)). */ +#define RESOLVE_CACHED 0x20 /* Only complete if resolution can be + completed through cached lookup. May + return -EAGAIN if that's not + possible. */ #endif /* _UAPI_LINUX_OPENAT2_H */ |