On Thu, Jan 12, 2017 at 07:42:22AM +0200, Amir Goldstein wrote:
> I think you suggested here to use a waitqueue for pending copyups?
> Did you mean a waitqueue per overlay parent directory inode or
> did you mean something else?
Something like this:
diff --git a/fs/overlayfs/ovl_entry.h b/fs/overlayfs/ovl_entry.h
index d14bca1850d9..a46e7e53cd7a 100644
--- a/fs/overlayfs/ovl_entry.h
+++ b/fs/overlayfs/ovl_entry.h
@@ -27,6 +27,7 @@ struct ovl_fs {
struct ovl_config config;
/* creds of process who forced instantiation of super block */
const struct cred *creator_cred;
+ wait_queue_head_t copyup_wq;
};
/* private information held for every overlayfs dentry */
@@ -38,6 +39,7 @@ struct ovl_entry {
u64 version;
const char *redirect;
bool opaque;
+ bool copying;
};
struct rcu_head rcu;
};
diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
index 952286f4826c..4e2b2c485165 100644
--- a/fs/overlayfs/util.c
+++ b/fs/overlayfs/util.c
@@ -263,3 +263,32 @@ struct file *ovl_path_open(struct path *path, int flags)
{
return dentry_open(path, flags | O_NOATIME, current_cred());
}
+
+int ovl_copy_up_start(struct dentry *dentry)
+{
+ struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
+ struct ovl_entry *oe = dentry->d_fsdata;
+ int err;
+
+ spin_lock(&ofs->copyup_wq.lock);
+ err = wait_event_interruptible_locked(ofs->copyup_wq, !oe->copying);
+ if (!err) {
+ if (oe->__upperdentry)
+ err = 1; /* Already copied up */
+ else
+ oe->copying = true;
+ }
+ spin_unlock(&ofs->copyup_wq.lock);
+
+ return err;
+}
+
+void ovl_copy_up_end(struct dentry *dentry)
+{
+ struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
+ struct ovl_entry *oe = dentry->d_fsdata;
+
+ spin_lock(&ofs->copyup_wq.lock);
+ oe->copying = false;
+ spin_unlock(&ofs->copyup_wq.lock);
+}
--
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