diff options
Diffstat (limited to 'kernel/fs/cachefiles/xattr.c')
| -rw-r--r-- | kernel/fs/cachefiles/xattr.c | 324 |
1 files changed, 324 insertions, 0 deletions
diff --git a/kernel/fs/cachefiles/xattr.c b/kernel/fs/cachefiles/xattr.c new file mode 100644 index 000000000..d31c1a72d --- /dev/null +++ b/kernel/fs/cachefiles/xattr.c @@ -0,0 +1,324 @@ +/* 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(d_backing_inode(dentry)); + + 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) { + pr_err("Can't set xattr on %pd [%lu] (err %d)\n", + dentry, d_backing_inode(dentry)->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; + + pr_err("Can't read xattr on %pd [%lu] (err %d)\n", + dentry, d_backing_inode(dentry)->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: + pr_err("Cache object %lu type xattr length incorrect\n", + d_backing_inode(dentry)->i_ino); + ret = -EIO; + goto error; + +bad_type: + xtype[2] = 0; + pr_err("Cache object %pd [%lu] type %s not %s\n", + dentry, d_backing_inode(dentry)->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(d_backing_inode(dentry)); + 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(d_backing_inode(dentry)); + + 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)", + d_backing_inode(dentry)->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)", + d_backing_inode(dentry)->i_ino, -ret); + goto error; + } + } + +okay: + ret = 0; + +error: + kfree(auxbuf); + _leave(" = %d", ret); + return ret; + +bad_type_length: + pr_err("Cache object %lu xattr length incorrect\n", + d_backing_inode(dentry)->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)", + d_backing_inode(dentry)->i_ino, -ret); + } + + _leave(" = %d", ret); + return ret; +} |