Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...
[sfrench/cifs-2.6.git] / fs / overlayfs / dir.c
index 839709c7803a59bdd2ee965d4ef768e60eae20a7..f480b1a2cd2e5ada2a7a3c978b00d541839b635a 100644 (file)
@@ -43,7 +43,7 @@ int ovl_cleanup(struct inode *wdir, struct dentry *wdentry)
        return err;
 }
 
-struct dentry *ovl_lookup_temp(struct dentry *workdir)
+static struct dentry *ovl_lookup_temp(struct dentry *workdir)
 {
        struct dentry *temp;
        char name[20];
@@ -114,36 +114,72 @@ kill_whiteout:
        goto out;
 }
 
-int ovl_create_real(struct inode *dir, struct dentry *newdentry,
-                   struct cattr *attr, struct dentry *hardlink, bool debug)
+static int ovl_mkdir_real(struct inode *dir, struct dentry **newdentry,
+                         umode_t mode)
 {
        int err;
+       struct dentry *d, *dentry = *newdentry;
 
+       err = ovl_do_mkdir(dir, dentry, mode);
+       if (err)
+               return err;
+
+       if (likely(!d_unhashed(dentry)))
+               return 0;
+
+       /*
+        * vfs_mkdir() may succeed and leave the dentry passed
+        * to it unhashed and negative. If that happens, try to
+        * lookup a new hashed and positive dentry.
+        */
+       d = lookup_one_len(dentry->d_name.name, dentry->d_parent,
+                          dentry->d_name.len);
+       if (IS_ERR(d)) {
+               pr_warn("overlayfs: failed lookup after mkdir (%pd2, err=%i).\n",
+                       dentry, err);
+               return PTR_ERR(d);
+       }
+       dput(dentry);
+       *newdentry = d;
+
+       return 0;
+}
+
+struct dentry *ovl_create_real(struct inode *dir, struct dentry *newdentry,
+                              struct ovl_cattr *attr)
+{
+       int err;
+
+       if (IS_ERR(newdentry))
+               return newdentry;
+
+       err = -ESTALE;
        if (newdentry->d_inode)
-               return -ESTALE;
+               goto out;
 
-       if (hardlink) {
-               err = ovl_do_link(hardlink, dir, newdentry, debug);
+       if (attr->hardlink) {
+               err = ovl_do_link(attr->hardlink, dir, newdentry);
        } else {
                switch (attr->mode & S_IFMT) {
                case S_IFREG:
-                       err = ovl_do_create(dir, newdentry, attr->mode, debug);
+                       err = ovl_do_create(dir, newdentry, attr->mode);
                        break;
 
                case S_IFDIR:
-                       err = ovl_do_mkdir(dir, newdentry, attr->mode, debug);
+                       /* mkdir is special... */
+                       err =  ovl_mkdir_real(dir, &newdentry, attr->mode);
                        break;
 
                case S_IFCHR:
                case S_IFBLK:
                case S_IFIFO:
                case S_IFSOCK:
-                       err = ovl_do_mknod(dir, newdentry,
-                                          attr->mode, attr->rdev, debug);
+                       err = ovl_do_mknod(dir, newdentry, attr->mode,
+                                          attr->rdev);
                        break;
 
                case S_IFLNK:
-                       err = ovl_do_symlink(dir, newdentry, attr->link, debug);
+                       err = ovl_do_symlink(dir, newdentry, attr->link);
                        break;
 
                default:
@@ -155,9 +191,20 @@ int ovl_create_real(struct inode *dir, struct dentry *newdentry,
                 * Not quite sure if non-instantiated dentry is legal or not.
                 * VFS doesn't seem to care so check and warn here.
                 */
-               err = -ENOENT;
+               err = -EIO;
        }
-       return err;
+out:
+       if (err) {
+               dput(newdentry);
+               return ERR_PTR(err);
+       }
+       return newdentry;
+}
+
+struct dentry *ovl_create_temp(struct dentry *workdir, struct ovl_cattr *attr)
+{
+       return ovl_create_real(d_inode(workdir), ovl_lookup_temp(workdir),
+                              attr);
 }
 
 static int ovl_set_opaque_xerr(struct dentry *dentry, struct dentry *upper,
@@ -182,24 +229,54 @@ static int ovl_set_opaque(struct dentry *dentry, struct dentry *upperdentry)
        return ovl_set_opaque_xerr(dentry, upperdentry, -EIO);
 }
 
-/* Common operations required to be done after creation of file on upper */
-static void ovl_instantiate(struct dentry *dentry, struct inode *inode,
-                           struct dentry *newdentry, bool hardlink)
+/*
+ * Common operations required to be done after creation of file on upper.
+ * If @hardlink is false, then @inode is a pre-allocated inode, we may or
+ * may not use to instantiate the new dentry.
+ */
+static int ovl_instantiate(struct dentry *dentry, struct inode *inode,
+                          struct dentry *newdentry, bool hardlink)
 {
+       struct ovl_inode_params oip = {
+               .upperdentry = newdentry,
+               .newinode = inode,
+       };
+
        ovl_dentry_version_inc(dentry->d_parent, false);
        ovl_dentry_set_upper_alias(dentry);
        if (!hardlink) {
-               ovl_inode_update(inode, newdentry);
-               ovl_copyattr(newdentry->d_inode, inode);
+               /*
+                * ovl_obtain_alias() can be called after ovl_create_real()
+                * and before we get here, so we may get an inode from cache
+                * with the same real upperdentry that is not the inode we
+                * pre-allocated.  In this case we will use the cached inode
+                * to instantiate the new dentry.
+                *
+                * XXX: if we ever use ovl_obtain_alias() to decode directory
+                * file handles, need to use ovl_get_inode_locked() and
+                * d_instantiate_new() here to prevent from creating two
+                * hashed directory inode aliases.
+                */
+               inode = ovl_get_inode(dentry->d_sb, &oip);
+               if (WARN_ON(IS_ERR(inode)))
+                       return PTR_ERR(inode);
        } else {
                WARN_ON(ovl_inode_real(inode) != d_inode(newdentry));
                dput(newdentry);
                inc_nlink(inode);
        }
+
        d_instantiate(dentry, inode);
+       if (inode != oip.newinode) {
+               pr_warn_ratelimited("overlayfs: newly created inode found in cache (%pd2)\n",
+                                   dentry);
+       }
+
        /* Force lookup of new upper hardlink to find its lower */
        if (hardlink)
                d_drop(dentry);
+
+       return 0;
 }
 
 static bool ovl_type_merge(struct dentry *dentry)
@@ -213,38 +290,42 @@ static bool ovl_type_origin(struct dentry *dentry)
 }
 
 static int ovl_create_upper(struct dentry *dentry, struct inode *inode,
-                           struct cattr *attr, struct dentry *hardlink)
+                           struct ovl_cattr *attr)
 {
        struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
        struct inode *udir = upperdir->d_inode;
        struct dentry *newdentry;
        int err;
 
-       if (!hardlink && !IS_POSIXACL(udir))
+       if (!attr->hardlink && !IS_POSIXACL(udir))
                attr->mode &= ~current_umask();
 
        inode_lock_nested(udir, I_MUTEX_PARENT);
-       newdentry = lookup_one_len(dentry->d_name.name, upperdir,
-                                  dentry->d_name.len);
+       newdentry = ovl_create_real(udir,
+                                   lookup_one_len(dentry->d_name.name,
+                                                  upperdir,
+                                                  dentry->d_name.len),
+                                   attr);
        err = PTR_ERR(newdentry);
        if (IS_ERR(newdentry))
                goto out_unlock;
-       err = ovl_create_real(udir, newdentry, attr, hardlink, false);
-       if (err)
-               goto out_dput;
 
        if (ovl_type_merge(dentry->d_parent) && d_is_dir(newdentry)) {
                /* Setting opaque here is just an optimization, allow to fail */
                ovl_set_opaque(dentry, newdentry);
        }
 
-       ovl_instantiate(dentry, inode, newdentry, !!hardlink);
-       newdentry = NULL;
-out_dput:
-       dput(newdentry);
+       err = ovl_instantiate(dentry, inode, newdentry, !!attr->hardlink);
+       if (err)
+               goto out_cleanup;
 out_unlock:
        inode_unlock(udir);
        return err;
+
+out_cleanup:
+       ovl_cleanup(udir, newdentry);
+       dput(newdentry);
+       goto out_unlock;
 }
 
 static struct dentry *ovl_clear_empty(struct dentry *dentry,
@@ -280,16 +361,11 @@ static struct dentry *ovl_clear_empty(struct dentry *dentry,
        if (upper->d_parent->d_inode != udir)
                goto out_unlock;
 
-       opaquedir = ovl_lookup_temp(workdir);
+       opaquedir = ovl_create_temp(workdir, OVL_CATTR(stat.mode));
        err = PTR_ERR(opaquedir);
        if (IS_ERR(opaquedir))
                goto out_unlock;
 
-       err = ovl_create_real(wdir, opaquedir,
-                             &(struct cattr){.mode = stat.mode}, NULL, true);
-       if (err)
-               goto out_dput;
-
        err = ovl_copy_xattr(upper, opaquedir);
        if (err)
                goto out_cleanup;
@@ -319,7 +395,6 @@ static struct dentry *ovl_clear_empty(struct dentry *dentry,
 
 out_cleanup:
        ovl_cleanup(wdir, opaquedir);
-out_dput:
        dput(opaquedir);
 out_unlock:
        unlock_rename(workdir, upperdir);
@@ -354,8 +429,7 @@ out_free:
 }
 
 static int ovl_create_over_whiteout(struct dentry *dentry, struct inode *inode,
-                                   struct cattr *cattr,
-                                   struct dentry *hardlink)
+                                   struct ovl_cattr *cattr)
 {
        struct dentry *workdir = ovl_workdir(dentry);
        struct inode *wdir = workdir->d_inode;
@@ -365,6 +439,7 @@ static int ovl_create_over_whiteout(struct dentry *dentry, struct inode *inode,
        struct dentry *newdentry;
        int err;
        struct posix_acl *acl, *default_acl;
+       bool hardlink = !!cattr->hardlink;
 
        if (WARN_ON(!workdir))
                return -EROFS;
@@ -380,20 +455,16 @@ static int ovl_create_over_whiteout(struct dentry *dentry, struct inode *inode,
        if (err)
                goto out;
 
-       newdentry = ovl_lookup_temp(workdir);
-       err = PTR_ERR(newdentry);
-       if (IS_ERR(newdentry))
-               goto out_unlock;
-
        upper = lookup_one_len(dentry->d_name.name, upperdir,
                               dentry->d_name.len);
        err = PTR_ERR(upper);
        if (IS_ERR(upper))
-               goto out_dput;
+               goto out_unlock;
 
-       err = ovl_create_real(wdir, newdentry, cattr, hardlink, true);
-       if (err)
-               goto out_dput2;
+       newdentry = ovl_create_temp(workdir, cattr);
+       err = PTR_ERR(newdentry);
+       if (IS_ERR(newdentry))
+               goto out_dput;
 
        /*
         * mode could have been mutilated due to umask (e.g. sgid directory)
@@ -439,12 +510,11 @@ static int ovl_create_over_whiteout(struct dentry *dentry, struct inode *inode,
                if (err)
                        goto out_cleanup;
        }
-       ovl_instantiate(dentry, inode, newdentry, !!hardlink);
-       newdentry = NULL;
-out_dput2:
-       dput(upper);
+       err = ovl_instantiate(dentry, inode, newdentry, hardlink);
+       if (err)
+               goto out_cleanup;
 out_dput:
-       dput(newdentry);
+       dput(upper);
 out_unlock:
        unlock_rename(workdir, upperdir);
 out:
@@ -456,12 +526,12 @@ out:
 
 out_cleanup:
        ovl_cleanup(wdir, newdentry);
-       goto out_dput2;
+       dput(newdentry);
+       goto out_dput;
 }
 
 static int ovl_create_or_link(struct dentry *dentry, struct inode *inode,
-                             struct cattr *attr, struct dentry *hardlink,
-                             bool origin)
+                             struct ovl_cattr *attr, bool origin)
 {
        int err;
        const struct cred *old_cred;
@@ -489,7 +559,7 @@ static int ovl_create_or_link(struct dentry *dentry, struct inode *inode,
        if (override_cred) {
                override_cred->fsuid = inode->i_uid;
                override_cred->fsgid = inode->i_gid;
-               if (!hardlink) {
+               if (!attr->hardlink) {
                        err = security_dentry_create_files_as(dentry,
                                        attr->mode, &dentry->d_name, old_cred,
                                        override_cred);
@@ -502,21 +572,12 @@ static int ovl_create_or_link(struct dentry *dentry, struct inode *inode,
                put_cred(override_cred);
 
                if (!ovl_dentry_is_whiteout(dentry))
-                       err = ovl_create_upper(dentry, inode, attr,
-                                               hardlink);
+                       err = ovl_create_upper(dentry, inode, attr);
                else
-                       err = ovl_create_over_whiteout(dentry, inode, attr,
-                                                       hardlink);
+                       err = ovl_create_over_whiteout(dentry, inode, attr);
        }
 out_revert_creds:
        revert_creds(old_cred);
-       if (!err) {
-               struct inode *realinode = d_inode(ovl_dentry_upper(dentry));
-
-               WARN_ON(inode->i_mode != realinode->i_mode);
-               WARN_ON(!uid_eq(inode->i_uid, realinode->i_uid));
-               WARN_ON(!gid_eq(inode->i_gid, realinode->i_gid));
-       }
        return err;
 }
 
@@ -525,7 +586,7 @@ static int ovl_create_object(struct dentry *dentry, int mode, dev_t rdev,
 {
        int err;
        struct inode *inode;
-       struct cattr attr = {
+       struct ovl_cattr attr = {
                .rdev = rdev,
                .link = link,
        };
@@ -534,6 +595,7 @@ static int ovl_create_object(struct dentry *dentry, int mode, dev_t rdev,
        if (err)
                goto out;
 
+       /* Preallocate inode to be used by ovl_get_inode() */
        err = -ENOMEM;
        inode = ovl_new_inode(dentry->d_sb, mode, rdev);
        if (!inode)
@@ -542,8 +604,9 @@ static int ovl_create_object(struct dentry *dentry, int mode, dev_t rdev,
        inode_init_owner(inode, dentry->d_parent->d_inode, mode);
        attr.mode = inode->i_mode;
 
-       err = ovl_create_or_link(dentry, inode, &attr, NULL, false);
-       if (err)
+       err = ovl_create_or_link(dentry, inode, &attr, false);
+       /* Did we end up using the preallocated inode? */
+       if (inode != d_inode(dentry))
                iput(inode);
 
 out_drop_write:
@@ -601,8 +664,9 @@ static int ovl_link(struct dentry *old, struct inode *newdir,
        inode = d_inode(old);
        ihold(inode);
 
-       err = ovl_create_or_link(new, inode, NULL, ovl_dentry_upper(old),
-                                ovl_type_origin(old));
+       err = ovl_create_or_link(new, inode,
+                       &(struct ovl_cattr) {.hardlink = ovl_dentry_upper(old)},
+                       ovl_type_origin(old));
        if (err)
                iput(inode);