try to get rid of races in hostfs open()
In case of mode mismatch, do *not* blindly close the descriptor
another openers might be using right now. Open the underlying
file with currently sufficient mode, then
* if current mode has grown so that it's sufficient for
us now, just close our new fd
* if current mode has grown and our fd is *not* enough
to cover it, close and repeat.
* otherwise, install our fd if the file hadn't been
opened at all or dup2() our fd over the current one (and close
our fd).
Critical section is protected by mutex; yes, system-wide. All
we do under it is a bunch of comparison and maybe an overwriting
dup2() on host.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/hostfs/hostfs.h b/fs/hostfs/hostfs.h
index ea87e22..6bbd75c 100644
--- a/fs/hostfs/hostfs.h
+++ b/fs/hostfs/hostfs.h
@@ -74,6 +74,7 @@
extern char *read_dir(void *stream, unsigned long long *pos,
unsigned long long *ino_out, int *len_out);
extern void close_file(void *stream);
+extern int replace_file(int oldfd, int fd);
extern void close_dir(void *stream);
extern int read_file(int fd, unsigned long long *offset, char *buf, int len);
extern int write_file(int fd, unsigned long long *offset, const char *buf,