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@xxxxxxxxxx> cc: linux-cachefs@xxxxxxxxxx Link: https://lore.kernel.org/r/163819631182.215744.3322471539523262619.stgit@xxxxxxxxxxxxxxxxxxxxxx/ # v1 Link: https://lore.kernel.org/r/163906933130.143852.962088616746509062.stgit@xxxxxxxxxxxxxxxxxxxxxx/ # v2 Link: https://lore.kernel.org/r/163967141952.1823006.7832985646370603833.stgit@xxxxxxxxxxxxxxxxxxxxxx/ # v3 --- fs/cachefiles/internal.h | 9 +++ fs/cachefiles/namei.c | 141 ++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 150 insertions(+) diff --git a/fs/cachefiles/internal.h b/fs/cachefiles/internal.h index 3783a3e01027..48768a3ab105 100644 --- a/fs/cachefiles/internal.h +++ b/fs/cachefiles/internal.h @@ -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 */ diff --git a/fs/cachefiles/namei.c b/fs/cachefiles/namei.c index 913f83f1c900..11a33209ab5f 100644 --- a/fs/cachefiles/namei.c +++ b/fs/cachefiles/namei.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); + } +}
