4 files changed, 142 insertions, 11 deletions

diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c
index aa3c62a4e462..7e6664d6643d 100644
--- a/fs/overlayfs/copy_up.c
+++ b/fs/overlayfs/copy_up.c
@@ -180,6 +180,16 @@ out_fput:
         return error;
 }
 
+static int ovl_set_size(struct dentry *upperdentry, struct kstat *stat)
+{
+        struct iattr attr = {
+                .ia_valid = ATTR_SIZE,
+                .ia_size = stat->size,
+        };
+
+        return notify_change(upperdentry, &attr, NULL);
+}
+
 static int ovl_set_timestamps(struct dentry *upperdentry, struct kstat *stat)
 {
         struct iattr attr = {
@@ -520,8 +530,18 @@ static int ovl_copy_up_inode(struct ovl_copy_up_ctx *c, struct dentry *temp)
                         return err;
         }
 
+        if (c->metacopy) {
+                err = ovl_check_setxattr(c->dentry, temp, OVL_XATTR_METACOPY,
+                                         NULL, 0, -EOPNOTSUPP);
+                if (err)
+                        return err;
+        }
+
         inode_lock(temp->d_inode);
-        err = ovl_set_attr(temp, &c->stat);
+        if (c->metacopy)
+                err = ovl_set_size(temp, &c->stat);
+        if (!err)
+                err = ovl_set_attr(temp, &c->stat);
         inode_unlock(temp->d_inode);
 
         return err;
@@ -559,6 +579,8 @@ static int ovl_copy_up_locked(struct ovl_copy_up_ctx *c)
         if (err)
                 goto out;
 
+        if (!c->metacopy)
+                ovl_set_upperdata(d_inode(c->dentry));
         inode = d_inode(c->dentry);
         ovl_inode_update(inode, newdentry);
         if (S_ISDIR(inode->i_mode))
@@ -681,6 +703,28 @@ static bool ovl_need_meta_copy_up(struct dentry *dentry, umode_t mode,
         return true;
 }
 
+/* Copy up data of an inode which was copied up metadata only in the past. */
+static int ovl_copy_up_meta_inode_data(struct ovl_copy_up_ctx *c)
+{
+        struct path upperpath;
+        int err;
+
+        ovl_path_upper(c->dentry, &upperpath);
+        if (WARN_ON(upperpath.dentry == NULL))
+                return -EIO;
+
+        err = ovl_copy_up_data(&c->lowerpath, &upperpath, c->stat.size);
+        if (err)
+                return err;
+
+        err = vfs_removexattr(upperpath.dentry, OVL_XATTR_METACOPY);
+        if (err)
+                return err;
+
+        ovl_set_upperdata(d_inode(c->dentry));
+        return err;
+}
+
 static int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry,
                            int flags)
 {
@@ -726,7 +770,7 @@ static int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry,
                         return PTR_ERR(ctx.link);
         }
 
-        err = ovl_copy_up_start(dentry);
+        err = ovl_copy_up_start(dentry, flags);
         /* err < 0: interrupted, err > 0: raced with another copy-up */
         if (unlikely(err)) {
                 if (err > 0)
@@ -736,6 +780,8 @@ static int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry,
                         err = ovl_do_copy_up(&ctx);
                 if (!err && parent && !ovl_dentry_has_upper_alias(dentry))
                         err = ovl_link_up(&ctx);
+                if (!err && ovl_dentry_needs_data_copy_up_locked(dentry, flags))
+                        err = ovl_copy_up_meta_inode_data(&ctx);
                 ovl_copy_up_end(dentry);
         }
         do_delayed_call(&done);
@@ -761,7 +807,7 @@ int ovl_copy_up_flags(struct dentry *dentry, int flags)
                 struct dentry *next;
                 struct dentry *parent = NULL;
 
-                if (ovl_already_copied_up(dentry))
+                if (ovl_already_copied_up(dentry, flags))
                         break;
 
                 next = dget(dentry);
@@ -789,13 +835,13 @@ 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_already_copied_up(dentry))
+        if (ovl_already_copied_up(dentry, flags))
                 return false;
 
         if (special_file(d_inode(dentry)->i_mode))
                 return false;
 
-        if (!(OPEN_FMODE(flags) & FMODE_WRITE) && !(flags & O_TRUNC))
+        if (!ovl_open_flags_need_copy_up(flags))
                 return false;
 
         return true;
diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index 206e588df095..16a000694c4e 100644
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -29,6 +29,7 @@ enum ovl_path_type {
 #define OVL_XATTR_IMPURE OVL_XATTR_PREFIX "impure"
 #define OVL_XATTR_NLINK OVL_XATTR_PREFIX "nlink"
 #define OVL_XATTR_UPPER OVL_XATTR_PREFIX "upper"
+#define OVL_XATTR_METACOPY OVL_XATTR_PREFIX "metacopy"
 
 enum ovl_inode_flag {
         /* Pure upper dir that may contain non pure upper entries */
@@ -36,6 +37,7 @@ enum ovl_inode_flag {
         /* Non-merge dir that may contain whiteout entries */
         OVL_WHITEOUTS,
         OVL_INDEX,
+        OVL_UPPERDATA,
 };
 
 enum ovl_entry_flag {
@@ -191,6 +193,14 @@ static inline struct dentry *ovl_do_tmpfile(struct dentry *dentry, umode_t mode)
         return ret;
 }
 
+static inline bool ovl_open_flags_need_copy_up(int flags)
+{
+        if (!flags)
+                return false;
+
+        return ((OPEN_FMODE(flags) & FMODE_WRITE) || (flags & O_TRUNC));
+}
+
 /* util.c */
 int ovl_want_write(struct dentry *dentry);
 void ovl_drop_write(struct dentry *dentry);
@@ -226,6 +236,10 @@ bool ovl_dentry_is_whiteout(struct dentry *dentry);
 void ovl_dentry_set_opaque(struct dentry *dentry);
 bool ovl_dentry_has_upper_alias(struct dentry *dentry);
 void ovl_dentry_set_upper_alias(struct dentry *dentry);
+bool ovl_dentry_needs_data_copy_up(struct dentry *dentry, int flags);
+bool ovl_dentry_needs_data_copy_up_locked(struct dentry *dentry, int flags);
+bool ovl_has_upperdata(struct inode *inode);
+void ovl_set_upperdata(struct inode *inode);
 bool ovl_redirect_dir(struct super_block *sb);
 const char *ovl_dentry_get_redirect(struct dentry *dentry);
 void ovl_dentry_set_redirect(struct dentry *dentry, const char *redirect);
@@ -236,9 +250,9 @@ void ovl_dir_modified(struct dentry *dentry, bool impurity);
 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);
+int ovl_copy_up_start(struct dentry *dentry, int flags);
 void ovl_copy_up_end(struct dentry *dentry);
-bool ovl_already_copied_up(struct dentry *dentry);
+bool ovl_already_copied_up(struct dentry *dentry, int flags);
 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/super.c b/fs/overlayfs/super.c
index d4caeee051ee..ab0039161f85 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -1485,6 +1485,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
         /* Root is always merge -> can have whiteouts */
         ovl_set_flag(OVL_WHITEOUTS, d_inode(root_dentry));
         ovl_dentry_set_flag(OVL_E_CONNECTED, root_dentry);
+        ovl_set_upperdata(d_inode(root_dentry));
         ovl_inode_init(d_inode(root_dentry), upperpath.dentry,
                        ovl_dentry_lower(root_dentry));
 
diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
index 43235294e77b..f8e3c95711b8 100644
--- a/fs/overlayfs/util.c
+++ b/fs/overlayfs/util.c
@@ -279,6 +279,62 @@ void ovl_dentry_set_upper_alias(struct dentry *dentry)
         ovl_dentry_set_flag(OVL_E_UPPER_ALIAS, dentry);
 }
 
+static bool ovl_should_check_upperdata(struct inode *inode)
+{
+        if (!S_ISREG(inode->i_mode))
+                return false;
+
+        if (!ovl_inode_lower(inode))
+                return false;
+
+        return true;
+}
+
+bool ovl_has_upperdata(struct inode *inode)
+{
+        if (!ovl_should_check_upperdata(inode))
+                return true;
+
+        if (!ovl_test_flag(OVL_UPPERDATA, inode))
+                return false;
+        /*
+         * Pairs with smp_wmb() in ovl_set_upperdata(). Main user of
+         * ovl_has_upperdata() is ovl_copy_up_meta_inode_data(). Make sure
+         * if setting of OVL_UPPERDATA is visible, then effects of writes
+         * before that are visible too.
+         */
+        smp_rmb();
+        return true;
+}
+
+void ovl_set_upperdata(struct inode *inode)
+{
+        /*
+         * Pairs with smp_rmb() in ovl_has_upperdata(). Make sure
+         * if OVL_UPPERDATA flag is visible, then effects of write operations
+         * before it are visible as well.
+         */
+        smp_wmb();
+        ovl_set_flag(OVL_UPPERDATA, inode);
+}
+
+/* Caller should hold ovl_inode->lock */
+bool ovl_dentry_needs_data_copy_up_locked(struct dentry *dentry, int flags)
+{
+        if (!ovl_open_flags_need_copy_up(flags))
+                return false;
+
+        return !ovl_test_flag(OVL_UPPERDATA, d_inode(dentry));
+}
+
+bool ovl_dentry_needs_data_copy_up(struct dentry *dentry, int flags)
+{
+        if (!ovl_open_flags_need_copy_up(flags))
+                return false;
+
+        return !ovl_has_upperdata(d_inode(dentry));
+}
+
 bool ovl_redirect_dir(struct super_block *sb)
 {
         struct ovl_fs *ofs = sb->s_fs_info;
@@ -377,7 +433,20 @@ 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)
+/* Caller should hold ovl_inode->lock */
+static bool ovl_already_copied_up_locked(struct dentry *dentry, int flags)
+{
+        bool disconnected = dentry->d_flags & DCACHE_DISCONNECTED;
+
+        if (ovl_dentry_upper(dentry) &&
+            (ovl_dentry_has_upper_alias(dentry) || disconnected) &&
+            !ovl_dentry_needs_data_copy_up_locked(dentry, flags))
+                return true;
+
+        return false;
+}
+
+bool ovl_already_copied_up(struct dentry *dentry, int flags)
 {
         bool disconnected = dentry->d_flags & DCACHE_DISCONNECTED;
 
@@ -395,19 +464,20 @@ bool ovl_already_copied_up(struct dentry *dentry)
          *      with rename.
          */
         if (ovl_dentry_upper(dentry) &&
-            (ovl_dentry_has_upper_alias(dentry) || disconnected))
+            (ovl_dentry_has_upper_alias(dentry) || disconnected) &&
+            !ovl_dentry_needs_data_copy_up(dentry, flags))
                 return true;
 
         return false;
 }
 
-int ovl_copy_up_start(struct dentry *dentry)
+int ovl_copy_up_start(struct dentry *dentry, int flags)
 {
         struct ovl_inode *oi = OVL_I(d_inode(dentry));
         int err;
 
         err = mutex_lock_interruptible(&oi->lock);
-        if (!err && ovl_already_copied_up(dentry)) {
+        if (!err && ovl_already_copied_up_locked(dentry, flags)) {
                 err = 1; /* Already copied up */
                 mutex_unlock(&oi->lock);
         }