@@ -125,6 +125,15 @@ 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,
+ bool *_is_new);
+extern void cachefiles_put_directory(struct dentry *dir);
+
/*
* security.c
*/
@@ -6,6 +6,7 @@
*/
#include <linux/fs.h>
+#include <linux/namei.h>
#include "internal.h"
/*
@@ -41,3 +42,143 @@ static void __cachefiles_unmark_inode_in_use(struct cachefiles_object *object,
inode->i_flags &= ~S_KERNEL_FILE;
trace_cachefiles_mark_inactive(object, inode);
}
+
+/*
+ * get a subdirectory
+ */
+struct dentry *cachefiles_get_directory(struct cachefiles_cache *cache,
+ struct dentry *dir,
+ const char *dirname,
+ bool *_is_new)
+{
+ struct dentry *subdir;
+ struct path path;
+ int ret;
+
+ _enter(",,%s", dirname);
+
+ /* search the current directory for the element name */
+ inode_lock_nested(d_inode(dir), I_MUTEX_PARENT);
+
+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)) {
+ 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))) {
+ cachefiles_put_directory(subdir);
+ goto retry;
+ }
+ ASSERT(d_backing_inode(subdir));
+
+ _debug("mkdir -> %pd{ino=%lu}",
+ subdir, d_backing_inode(subdir)->i_ino);
+ if (_is_new)
+ *_is_new = true;
+ }
+
+ /* Tell rmdir() it's not allowed to delete the subdir */
+ inode_lock(d_inode(subdir));
+ inode_unlock(d_inode(dir));
+
+ if (!__cachefiles_mark_inode_in_use(NULL, subdir))
+ goto mark_error;
+
+ inode_unlock(d_inode(subdir));
+
+ /* 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:
+ cachefiles_put_directory(subdir);
+ _leave(" = %d [check]", ret);
+ return ERR_PTR(ret);
+
+mark_error:
+ inode_unlock(d_inode(subdir));
+ dput(subdir);
+ return ERR_PTR(-EBUSY);
+
+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);
+}
+
+/*
+ * Put a subdirectory.
+ */
+void cachefiles_put_directory(struct dentry *dir)
+{
+ if (dir) {
+ inode_lock(dir->d_inode);
+ __cachefiles_unmark_inode_in_use(NULL, dir);
+ inode_unlock(dir->d_inode);
+ dput(dir);
+ }
+}
Implement a function to get/create structural directories in the cache. This is used for setting up a cache and creating volume substructures. The directory in memory are marked with the S_KERNEL_FILE inode flag whilst they're in use to tell rmdir to reject attempts to remove them. Changes ======= ver #3: - Return an indication as to whether the directory was freshly created. Signed-off-by: David Howells <dhowells@redhat.com> cc: linux-cachefs@redhat.com Link: https://lore.kernel.org/r/163819631182.215744.3322471539523262619.stgit@warthog.procyon.org.uk/ # v1 Link: https://lore.kernel.org/r/163906933130.143852.962088616746509062.stgit@warthog.procyon.org.uk/ # v2 --- fs/cachefiles/internal.h | 9 +++ fs/cachefiles/namei.c | 141 ++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 150 insertions(+)