ovl: Add helper ovl_already_copied_up()

There are couple of places where we need to know if file is already copied
up (in lockless manner).  Right now its open coded and there are only two
conditions to check.  Soon this patch series will introduce another
condition to check and Amir wants to introduce one more.  So introduce a
helper instead to check this so that code is easier to read.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c
index d23467976725454aa3106cfe83810216c8e5d9af..aa3c62a4e4624bdcdc958814f530014c782eddbb 100644 (file)
--- a/fs/overlayfs/copy_up.c
+++ b/fs/overlayfs/copy_up.c
@@ -761,21 +761,7 @@ int ovl_copy_up_flags(struct dentry *dentry, int flags)
                struct dentry *next;
                struct dentry *parent = NULL;
 
-               /*
-                * Check if copy-up has happened as well as for upper alias (in
-                * case of hard links) is there.
-                *
-                * Both checks are lockless:
-                *  - false negatives: will recheck under oi->lock
-                *  - false positives:
-                *    + ovl_dentry_upper() uses memory barriers to ensure the
-                *      upper dentry is up-to-date
-                *    + ovl_dentry_has_upper_alias() relies on locking of
-                *      upper parent i_rwsem to prevent reordering copy-up
-                *      with rename.
-                */
-               if (ovl_dentry_upper(dentry) &&
-                   (ovl_dentry_has_upper_alias(dentry) || disconnected))
+               if (ovl_already_copied_up(dentry))
                        break;
 
                next = dget(dentry);
@@ -803,9 +789,7 @@ int ovl_copy_up_flags(struct dentry *dentry, int flags)
 static bool ovl_open_need_copy_up(struct dentry *dentry, int flags)
 {
        /* Copy up of disconnected dentry does not set upper alias */
-       if (ovl_dentry_upper(dentry) &&
-           (ovl_dentry_has_upper_alias(dentry) ||
-            (dentry->d_flags & DCACHE_DISCONNECTED)))
+       if (ovl_already_copied_up(dentry))
                return false;
 
        if (special_file(d_inode(dentry)->i_mode))

diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index c0318b5a50f09750af67bab23426296fbec281b6..206e588df095a81e72c16fdbc23fd50f7be38a9d 100644 (file)
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -238,6 +238,7 @@ 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);
+bool ovl_already_copied_up(struct dentry *dentry);
 bool ovl_check_origin_xattr(struct dentry *dentry);
 bool ovl_check_dir_xattr(struct dentry *dentry, const char *name);
 int ovl_check_setxattr(struct dentry *dentry, struct dentry *upperdentry,

diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
index 25d202b473262274468906dd9d547599ed594152..43235294e77bd5f41302bf1d5effa89500103836 100644 (file)
--- a/fs/overlayfs/util.c
+++ b/fs/overlayfs/util.c
@@ -377,13 +377,37 @@ struct file *ovl_path_open(struct path *path, int flags)
        return dentry_open(path, flags | O_NOATIME, current_cred());
 }
 
+bool ovl_already_copied_up(struct dentry *dentry)
+{
+       bool disconnected = dentry->d_flags & DCACHE_DISCONNECTED;
+
+       /*
+        * Check if copy-up has happened as well as for upper alias (in
+        * case of hard links) is there.
+        *
+        * Both checks are lockless:
+        *  - false negatives: will recheck under oi->lock
+        *  - false positives:
+        *    + ovl_dentry_upper() uses memory barriers to ensure the
+        *      upper dentry is up-to-date
+        *    + ovl_dentry_has_upper_alias() relies on locking of
+        *      upper parent i_rwsem to prevent reordering copy-up
+        *      with rename.
+        */
+       if (ovl_dentry_upper(dentry) &&
+           (ovl_dentry_has_upper_alias(dentry) || disconnected))
+               return true;
+
+       return false;
+}
+
 int ovl_copy_up_start(struct dentry *dentry)
 {
        struct ovl_inode *oi = OVL_I(d_inode(dentry));
        int err;
 
        err = mutex_lock_interruptible(&oi->lock);
-       if (!err && ovl_dentry_has_upper_alias(dentry)) {
+       if (!err && ovl_already_copied_up(dentry)) {
                err = 1; /* Already copied up */
                mutex_unlock(&oi->lock);
        }