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ovl: introduce copy up waitqueue 

The overlay sb 'copyup_wq' and overlay inode 'copying' condition
variable are about to replace the upper sb rename_lock, as finer
grained synchronization objects for concurrent copy up.

Suggested-by: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
This commit is contained in:
Amir Goldstein 2017-01-17 06:34:56 +02:00 committed by Miklos Szeredi
parent d8514d8edb
commit 39d3d60a54
4 changed files with 35 additions and 0 deletions
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2
fs/overlayfs/overlayfs.h
View File

@ -178,6 +178,8 @@ void ovl_dentry_version_inc(struct dentry *dentry);
u64 ovl_dentry_version_get(struct dentry *dentry);
bool ovl_is_whiteout(struct dentry *dentry);
struct file *ovl_path_open(struct path *path, int flags);
int ovl_copy_up_start(struct dentry *dentry);
void ovl_copy_up_end(struct dentry *dentry);
/* namei.c */
int ovl_path_next(int idx, struct dentry *dentry, struct path *path);

2
fs/overlayfs/ovl_entry.h
View File

@ -28,6 +28,7 @@ struct ovl_fs {
/* creds of process who forced instantiation of super block */
const struct cred *creator_cred;
bool tmpfile;
wait_queue_head_t copyup_wq;
};
/* private information held for every overlayfs dentry */
@ -39,6 +40,7 @@ struct ovl_entry {
u64 version;
const char *redirect;
bool opaque;
bool copying;
};
struct rcu_head rcu;
};

1
fs/overlayfs/super.c
View File

@ -708,6 +708,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
if (!ufs)
goto out;
init_waitqueue_head(&ufs->copyup_wq);
ufs->config.redirect_dir = ovl_redirect_dir_def;
err = ovl_parse_opt((char *) data, &ufs->config);
if (err)

30
fs/overlayfs/util.c
View File

@ -263,3 +263,33 @@ 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;
wake_up_locked(&ofs->copyup_wq);
spin_unlock(&ofs->copyup_wq.lock);
}