Implement a function to get/create structural directories in the cache.
This is used for setting up a cache and creating volume substructures.
Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
cc: linux-cachefs@xxxxxxxxxx
---
fs/cachefiles/Makefile | 3 +
fs/cachefiles/internal.h | 7 ++
fs/cachefiles/namei.c | 133 ++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 142 insertions(+), 1 deletion(-)
create mode 100644 fs/cachefiles/namei.c
diff --git a/fs/cachefiles/Makefile b/fs/cachefiles/Makefile
index 4c80d9af151f..06a87f78b88c 100644
--- a/fs/cachefiles/Makefile
+++ b/fs/cachefiles/Makefile
@@ -5,7 +5,8 @@
cachefiles-y := \
daemon.o \
- main.o
+ main.o \
+ namei.o
cachefiles-$(CONFIG_CACHEFILES_ERROR_INJECTION) += error_inject.o
diff --git a/fs/cachefiles/internal.h b/fs/cachefiles/internal.h
index 3ccc8411c502..4e77c3004d98 100644
--- a/fs/cachefiles/internal.h
+++ b/fs/cachefiles/internal.h
@@ -168,6 +168,13 @@ static inline int cachefiles_inject_remove_error(void)
return cachefiles_error_injection_state & 2 ? -EIO : 0;
}
+/*
+ * namei.c
+ */
+extern struct dentry *cachefiles_get_directory(struct cachefiles_cache *cache,
+ struct dentry *dir,
+ const char *name);
+
/*
* error handling
*/
diff --git a/fs/cachefiles/namei.c b/fs/cachefiles/namei.c
new file mode 100644
index 000000000000..69915dde0a83
--- /dev/null
+++ b/fs/cachefiles/namei.c
@@ -0,0 +1,133 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* CacheFiles path walking and related routines
+ *
+ * Copyright (C) 2021 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@xxxxxxxxxx)
+ */
+
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/file.h>
+#include <linux/fs.h>
+#include <linux/fsnotify.h>
+#include <linux/quotaops.h>
+#include <linux/xattr.h>
+#include <linux/mount.h>
+#include <linux/namei.h>
+#include <linux/security.h>
+#include <linux/slab.h>
+#include "internal.h"
+
+/*
+ * get a subdirectory
+ */
+struct dentry *cachefiles_get_directory(struct cachefiles_cache *cache,
+ struct dentry *dir,
+ const char *dirname)
+{
+ struct dentry *subdir;
+ struct path path;
+ int ret;
+
+ _enter(",,%s", dirname);
+
+ /* search the current directory for the element name */
+ inode_lock(d_inode(dir));
+
+retry:
+ ret = cachefiles_inject_read_error();
+ if (ret == 0)
+ subdir = lookup_one_len(dirname, dir, strlen(dirname));
+ else
+ subdir = ERR_PTR(ret);
+ if (IS_ERR(subdir)) {
+ trace_cachefiles_vfs_error(NULL, d_backing_inode(dir),
+ PTR_ERR(subdir),
+ cachefiles_trace_lookup_error);
+ if (PTR_ERR(subdir) == -ENOMEM)
+ goto nomem_d_alloc;
+ goto lookup_error;
+ }
+
+ _debug("subdir -> %pd %s",
+ subdir, d_backing_inode(subdir) ? "positive" : "negative");
+
+ /* we need to create the subdir if it doesn't exist yet */
+ if (d_is_negative(subdir)) {
+ if (cache->store) {
+ ret = cachefiles_has_space(cache, 1, 0);
+ if (ret < 0)
+ goto mkdir_error;
+ }
+
+ _debug("attempt mkdir");
+
+ path.mnt = cache->mnt;
+ path.dentry = dir;
+ ret = security_path_mkdir(&path, subdir, 0700);
+ if (ret < 0)
+ goto mkdir_error;
+ ret = cachefiles_inject_write_error();
+ if (ret == 0)
+ ret = vfs_mkdir(&init_user_ns, d_inode(dir), subdir, 0700);
+ if (ret < 0) {
+ trace_cachefiles_vfs_error(NULL, d_inode(dir), ret,
+ cachefiles_trace_mkdir_error);
+ goto mkdir_error;
+ }
+
+ if (unlikely(d_unhashed(subdir))) {
+ dput(subdir);
+ goto retry;
+ }
+ ASSERT(d_backing_inode(subdir));
+
+ _debug("mkdir -> %pd{ino=%lu}",
+ subdir, d_backing_inode(subdir)->i_ino);
+ }
+
+ inode_unlock(d_inode(dir));
+
+ /* we need to make sure the subdir is a directory */
+ ASSERT(d_backing_inode(subdir));
+
+ if (!d_can_lookup(subdir)) {
+ pr_err("%s is not a directory\n", dirname);
+ ret = -EIO;
+ goto check_error;
+ }
+
+ ret = -EPERM;
+ if (!(d_backing_inode(subdir)->i_opflags & IOP_XATTR) ||
+ !d_backing_inode(subdir)->i_op->lookup ||
+ !d_backing_inode(subdir)->i_op->mkdir ||
+ !d_backing_inode(subdir)->i_op->rename ||
+ !d_backing_inode(subdir)->i_op->rmdir ||
+ !d_backing_inode(subdir)->i_op->unlink)
+ goto check_error;
+
+ _leave(" = [%lu]", d_backing_inode(subdir)->i_ino);
+ return subdir;
+
+check_error:
+ dput(subdir);
+ _leave(" = %d [check]", ret);
+ return ERR_PTR(ret);
+
+mkdir_error:
+ inode_unlock(d_inode(dir));
+ dput(subdir);
+ pr_err("mkdir %s failed with error %d\n", dirname, ret);
+ return ERR_PTR(ret);
+
+lookup_error:
+ inode_unlock(d_inode(dir));
+ ret = PTR_ERR(subdir);
+ pr_err("Lookup %s failed with error %d\n", dirname, ret);
+ return ERR_PTR(ret);
+
+nomem_d_alloc:
+ inode_unlock(d_inode(dir));
+ _leave(" = -ENOMEM");
+ return ERR_PTR(-ENOMEM);
+}
