/* CacheFiles extended attribute management * * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved. * Written by David Howells (dhowells@redhat.com) * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public Licence * as published by the Free Software Foundation; either version * 2 of the Licence, or (at your option) any later version. */ #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/slab.h> #include "internal.h" static const char cachefiles_xattr_cache[] = XATTR_USER_PREFIX "CacheFiles.cache"; /* * check the type label on an object * - done using xattrs */ int cachefiles_check_object_type(struct cachefiles_object *object) { struct dentry *dentry = object->dentry; char type[3], xtype[3]; int ret; ASSERT(dentry); ASSERT(dentry->d_inode); if (!object->fscache.cookie) strcpy(type, "C3"); else snprintf(type, 3, "%02x", object->fscache.cookie->def->type); _enter("%p{%s}", object, type); /* attempt to install a type label directly */ ret = vfs_setxattr(dentry, cachefiles_xattr_cache, type, 2, XATTR_CREATE); if (ret == 0) { _debug("SET"); /* we succeeded */ goto error; } if (ret != -EEXIST) { kerror("Can't set xattr on %*.*s [%lu] (err %d)", dentry->d_name.len, dentry->d_name.len, dentry->d_name.name, dentry->d_inode->i_ino, -ret); goto error; } /* read the current type label */ ret = vfs_getxattr(dentry, cachefiles_xattr_cache, xtype, 3); if (ret < 0) { if (ret == -ERANGE) goto bad_type_length; kerror("Can't read xattr on %*.*s [%lu] (err %d)", dentry->d_name.len, dentry->d_name.len, dentry->d_name.name, dentry->d_inode->i_ino, -ret); goto error; } /* check the type is what we're expecting */ if (ret != 2) goto bad_type_length; if (xtype[0] != type[0] || xtype[1] != type[1]) goto bad_type; ret = 0; error: _leave(" = %d", ret); return ret; bad_type_length: kerror("Cache object %lu type xattr length incorrect", dentry->d_inode->i_ino); ret = -EIO; goto error; bad_type: xtype[2] = 0; kerror("Cache object %*.*s [%lu] type %s not %s", dentry->d_name.len, dentry->d_name.len, dentry->d_name.name, dentry->d_inode->i_ino, xtype, type); ret = -EIO; goto error; } /* * set the state xattr on a cache file */ int cachefiles_set_object_xattr(struct cachefiles_object *object, struct cachefiles_xattr *auxdata) { struct dentry *dentry = object->dentry; int ret; ASSERT(dentry); _enter("%p,#%d", object, auxdata->len); /* attempt to install the cache metadata directly */ _debug("SET #%u", auxdata->len); ret = vfs_setxattr(dentry, cachefiles_xattr_cache, &auxdata->type, auxdata->len, XATTR_CREATE); if (ret < 0 && ret != -ENOMEM) cachefiles_io_error_obj( object, "Failed to set xattr with error %d", ret); _leave(" = %d", ret); return ret; } /* * update the state xattr on a cache file */ int cachefiles_update_object_xattr(struct cachefiles_object *object, struct cachefiles_xattr *auxdata) { struct dentry *dentry = object->dentry; int ret; ASSERT(dentry); _enter("%p,#%d", object, auxdata->len); /* attempt to install the cache metadata directly */ _debug("SET #%u", auxdata->len); ret = vfs_setxattr(dentry, cachefiles_xattr_cache, &auxdata->type, auxdata->len, XATTR_REPLACE); if (ret < 0 && ret != -ENOMEM) cachefiles_io_error_obj( object, "Failed to update xattr with error %d", ret); _leave(" = %d", ret); return ret; } /* * check the consistency between the backing cache and the FS-Cache cookie */ int cachefiles_check_auxdata(struct cachefiles_object *object) { struct cachefiles_xattr *auxbuf; enum fscache_checkaux validity; struct dentry *dentry = object->dentry; ssize_t xlen; int ret; ASSERT(dentry); ASSERT(dentry->d_inode); ASSERT(object->fscache.cookie->def->check_aux); auxbuf = kmalloc(sizeof(struct cachefiles_xattr) + 512, GFP_KERNEL); if (!auxbuf) return -ENOMEM; xlen = vfs_getxattr(dentry, cachefiles_xattr_cache, &auxbuf->type, 512 + 1); ret = -ESTALE; if (xlen < 1 || auxbuf->type != object->fscache.cookie->def->type) goto error; xlen--; validity = fscache_check_aux(&object->fscache, &auxbuf->data, xlen); if (validity != FSCACHE_CHECKAUX_OKAY) goto error; ret = 0; error: kfree(auxbuf); return ret; } /* * check the state xattr on a cache file * - return -ESTALE if the object should be deleted */ int cachefiles_check_object_xattr(struct cachefiles_object *object, struct cachefiles_xattr *auxdata) { struct cachefiles_xattr *auxbuf; struct dentry *dentry = object->dentry; int ret; _enter("%p,#%d", object, auxdata->len); ASSERT(dentry); ASSERT(dentry->d_inode); auxbuf = kmalloc(sizeof(struct cachefiles_xattr) + 512, cachefiles_gfp); if (!auxbuf) { _leave(" = -ENOMEM"); return -ENOMEM; } /* read the current type label */ ret = vfs_getxattr(dentry, cachefiles_xattr_cache, &auxbuf->type, 512 + 1); if (ret < 0) { if (ret == -ENODATA) goto stale; /* no attribute - power went off * mid-cull? */ if (ret == -ERANGE) goto bad_type_length; cachefiles_io_error_obj(object, "Can't read xattr on %lu (err %d)", dentry->d_inode->i_ino, -ret); goto error; } /* check the on-disk object */ if (ret < 1) goto bad_type_length; if (auxbuf->type != auxdata->type) goto stale; auxbuf->len = ret; /* consult the netfs */ if (object->fscache.cookie->def->check_aux) { enum fscache_checkaux result; unsigned int dlen; dlen = auxbuf->len - 1; _debug("checkaux %s #%u", object->fscache.cookie->def->name, dlen); result = fscache_check_aux(&object->fscache, &auxbuf->data, dlen); switch (result) { /* entry okay as is */ case FSCACHE_CHECKAUX_OKAY: goto okay; /* entry requires update */ case FSCACHE_CHECKAUX_NEEDS_UPDATE: break; /* entry requires deletion */ case FSCACHE_CHECKAUX_OBSOLETE: goto stale; default: BUG(); } /* update the current label */ ret = vfs_setxattr(dentry, cachefiles_xattr_cache, &auxdata->type, auxdata->len, XATTR_REPLACE); if (ret < 0) { cachefiles_io_error_obj(object, "Can't update xattr on %lu" " (error %d)", dentry->d_inode->i_ino, -ret); goto error; } } okay: ret = 0; error: kfree(auxbuf); _leave(" = %d", ret); return ret; bad_type_length: kerror("Cache object %lu xattr length incorrect", dentry->d_inode->i_ino); ret = -EIO; goto error; stale: ret = -ESTALE; goto error; } /* * remove the object's xattr to mark it stale */ int cachefiles_remove_object_xattr(struct cachefiles_cache *cache, struct dentry *dentry) { int ret; ret = vfs_removexattr(dentry, cachefiles_xattr_cache); if (ret < 0) { if (ret == -ENOENT || ret == -ENODATA) ret = 0; else if (ret != -ENOMEM) cachefiles_io_error(cache, "Can't remove xattr from %lu" " (error %d)", dentry->d_inode->i_ino, -ret); } _leave(" = %d", ret); return ret; }