1 /* AFS silly rename handling 2 * 3 * Copyright (C) 2019 Red Hat, Inc. All Rights Reserved. 4 * Written by David Howells (dhowells@redhat.com) 5 * - Derived from NFS's sillyrename. 6 * 7 * This program is free software; you can redistribute it and/or 8 * modify it under the terms of the GNU General Public Licence 9 * as published by the Free Software Foundation; either version 10 * 2 of the Licence, or (at your option) any later version. 11 */ 12 13 #include <linux/kernel.h> 14 #include <linux/fs.h> 15 #include <linux/namei.h> 16 #include <linux/fsnotify.h> 17 #include "internal.h" 18 19 /* 20 * Actually perform the silly rename step. 21 */ 22 static int afs_do_silly_rename(struct afs_vnode *dvnode, struct afs_vnode *vnode, 23 struct dentry *old, struct dentry *new, 24 struct key *key) 25 { 26 struct afs_fs_cursor fc; 27 u64 dir_data_version = dvnode->status.data_version; 28 int ret = -ERESTARTSYS; 29 30 _enter("%pd,%pd", old, new); 31 32 trace_afs_silly_rename(vnode, false); 33 if (afs_begin_vnode_operation(&fc, dvnode, key)) { 34 while (afs_select_fileserver(&fc)) { 35 fc.cb_break = afs_calc_vnode_cb_break(dvnode); 36 afs_fs_rename(&fc, old->d_name.name, 37 dvnode, new->d_name.name, 38 dir_data_version, dir_data_version); 39 } 40 41 afs_vnode_commit_status(&fc, dvnode, fc.cb_break); 42 ret = afs_end_vnode_operation(&fc); 43 } 44 45 if (ret == 0) { 46 spin_lock(&old->d_lock); 47 old->d_flags |= DCACHE_NFSFS_RENAMED; 48 spin_unlock(&old->d_lock); 49 if (dvnode->silly_key != key) { 50 key_put(dvnode->silly_key); 51 dvnode->silly_key = key_get(key); 52 } 53 54 if (test_bit(AFS_VNODE_DIR_VALID, &dvnode->flags)) 55 afs_edit_dir_remove(dvnode, &old->d_name, 56 afs_edit_dir_for_silly_0); 57 if (test_bit(AFS_VNODE_DIR_VALID, &dvnode->flags)) 58 afs_edit_dir_add(dvnode, &new->d_name, 59 &vnode->fid, afs_edit_dir_for_silly_1); 60 61 /* vfs_unlink and the like do not issue this when a file is 62 * sillyrenamed, so do it here. 63 */ 64 fsnotify_nameremove(old, 0); 65 } 66 67 _leave(" = %d", ret); 68 return ret; 69 } 70 71 /** 72 * afs_sillyrename - Perform a silly-rename of a dentry 73 * 74 * AFS is stateless and the server doesn't know when the client is holding a 75 * file open. To prevent application problems when a file is unlinked while 76 * it's still open, the client performs a "silly-rename". That is, it renames 77 * the file to a hidden file in the same directory, and only performs the 78 * unlink once the last reference to it is put. 79 * 80 * The final cleanup is done during dentry_iput. 81 */ 82 int afs_sillyrename(struct afs_vnode *dvnode, struct afs_vnode *vnode, 83 struct dentry *dentry, struct key *key) 84 { 85 static unsigned int sillycounter; 86 struct dentry *sdentry = NULL; 87 unsigned char silly[16]; 88 int ret = -EBUSY; 89 90 _enter(""); 91 92 /* We don't allow a dentry to be silly-renamed twice. */ 93 if (dentry->d_flags & DCACHE_NFSFS_RENAMED) 94 return -EBUSY; 95 96 sdentry = NULL; 97 do { 98 int slen; 99 100 dput(sdentry); 101 sillycounter++; 102 103 /* Create a silly name. Note that the ".__afs" prefix is 104 * understood by the salvager and must not be changed. 105 */ 106 slen = scnprintf(silly, sizeof(silly), ".__afs%04X", sillycounter); 107 sdentry = lookup_one_len(silly, dentry->d_parent, slen); 108 109 /* N.B. Better to return EBUSY here ... it could be dangerous 110 * to delete the file while it's in use. 111 */ 112 if (IS_ERR(sdentry)) 113 goto out; 114 } while (!d_is_negative(sdentry)); 115 116 ihold(&vnode->vfs_inode); 117 118 ret = afs_do_silly_rename(dvnode, vnode, dentry, sdentry, key); 119 switch (ret) { 120 case 0: 121 /* The rename succeeded. */ 122 d_move(dentry, sdentry); 123 break; 124 case -ERESTARTSYS: 125 /* The result of the rename is unknown. Play it safe by forcing 126 * a new lookup. 127 */ 128 d_drop(dentry); 129 d_drop(sdentry); 130 } 131 132 iput(&vnode->vfs_inode); 133 dput(sdentry); 134 out: 135 _leave(" = %d", ret); 136 return ret; 137 } 138 139 /* 140 * Tell the server to remove a sillyrename file. 141 */ 142 static int afs_do_silly_unlink(struct afs_vnode *dvnode, struct afs_vnode *vnode, 143 struct dentry *dentry, struct key *key) 144 { 145 struct afs_fs_cursor fc; 146 u64 dir_data_version = dvnode->status.data_version; 147 int ret = -ERESTARTSYS; 148 149 _enter(""); 150 151 trace_afs_silly_rename(vnode, true); 152 if (afs_begin_vnode_operation(&fc, dvnode, key)) { 153 while (afs_select_fileserver(&fc)) { 154 fc.cb_break = afs_calc_vnode_cb_break(dvnode); 155 156 if (test_bit(AFS_SERVER_FL_IS_YFS, &fc.cbi->server->flags) && 157 !test_bit(AFS_SERVER_FL_NO_RM2, &fc.cbi->server->flags)) { 158 yfs_fs_remove_file2(&fc, vnode, dentry->d_name.name, 159 dir_data_version); 160 if (fc.ac.error != -ECONNABORTED || 161 fc.ac.abort_code != RXGEN_OPCODE) 162 continue; 163 set_bit(AFS_SERVER_FL_NO_RM2, &fc.cbi->server->flags); 164 } 165 166 afs_fs_remove(&fc, vnode, dentry->d_name.name, false, 167 dir_data_version); 168 } 169 170 afs_vnode_commit_status(&fc, dvnode, fc.cb_break); 171 ret = afs_end_vnode_operation(&fc); 172 if (ret == 0) { 173 drop_nlink(&vnode->vfs_inode); 174 if (vnode->vfs_inode.i_nlink == 0) { 175 set_bit(AFS_VNODE_DELETED, &vnode->flags); 176 clear_bit(AFS_VNODE_CB_PROMISED, &vnode->flags); 177 } 178 } 179 if (ret == 0 && 180 test_bit(AFS_VNODE_DIR_VALID, &dvnode->flags)) 181 afs_edit_dir_remove(dvnode, &dentry->d_name, 182 afs_edit_dir_for_unlink); 183 } 184 185 _leave(" = %d", ret); 186 return ret; 187 } 188 189 /* 190 * Remove sillyrename file on iput. 191 */ 192 int afs_silly_iput(struct dentry *dentry, struct inode *inode) 193 { 194 struct afs_vnode *dvnode = AFS_FS_I(d_inode(dentry->d_parent)); 195 struct afs_vnode *vnode = AFS_FS_I(inode); 196 struct dentry *alias; 197 int ret; 198 199 DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); 200 201 _enter("%p{%pd},%llx", dentry, dentry, vnode->fid.vnode); 202 203 down_read(&dvnode->rmdir_lock); 204 205 alias = d_alloc_parallel(dentry->d_parent, &dentry->d_name, &wq); 206 if (IS_ERR(alias)) { 207 up_read(&dvnode->rmdir_lock); 208 return 0; 209 } 210 211 if (!d_in_lookup(alias)) { 212 /* We raced with lookup... See if we need to transfer the 213 * sillyrename information to the aliased dentry. 214 */ 215 ret = 0; 216 spin_lock(&alias->d_lock); 217 if (d_really_is_positive(alias) && 218 !(alias->d_flags & DCACHE_NFSFS_RENAMED)) { 219 alias->d_flags |= DCACHE_NFSFS_RENAMED; 220 ret = 1; 221 } 222 spin_unlock(&alias->d_lock); 223 up_read(&dvnode->rmdir_lock); 224 dput(alias); 225 return ret; 226 } 227 228 /* Stop lock-release from complaining. */ 229 spin_lock(&vnode->lock); 230 vnode->lock_state = AFS_VNODE_LOCK_DELETED; 231 trace_afs_flock_ev(vnode, NULL, afs_flock_silly_delete, 0); 232 spin_unlock(&vnode->lock); 233 234 afs_do_silly_unlink(dvnode, vnode, dentry, dvnode->silly_key); 235 up_read(&dvnode->rmdir_lock); 236 d_lookup_done(alias); 237 dput(alias); 238 return 1; 239 } 240