Perhaps, we can add O_LOCK_FLAGS, then something like
--- a/fs/fcntl.c
+++ b/fs/fcntl.c
@@ -175,6 +175,15 @@ static int setfl(int fd, struct file * f
if (error)
return error;
+ spin_lock(¤t->files->file_lock);
+ if (!(filp->f_flags & O_LOCK_FLAGS))
+ filp->f_flags |= O_LOCK_FLAGS;
+ else
+ error = -EAGAIN;
+ spin_unlock(¤t->files->file_lock);
+ if (error) /* pretend ->f_flags was changed after us */
+ return 0;
+
if ((arg ^ filp->f_flags) & FASYNC) {
if (filp->f_op && filp->f_op->fasync) {
error = filp->f_op->fasync(fd, filp, (arg & FASYNC) != 0);
@@ -183,7 +192,8 @@ static int setfl(int fd, struct file * f
}
}
- filp->f_flags = (arg & SETFL_MASK) | (filp->f_flags & ~SETFL_MASK);
+ filp->f_flags = (arg & SETFL_MASK) |
+ (filp->f_flags & ~(SETFL_MASK | O_LOCK_FLAGS));
out:
return error;
}
What do you think?
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