1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* AFS silly rename handling 3 * 4 * Copyright (C) 2019 Red Hat, Inc. All Rights Reserved. 5 * Written by David Howells (dhowells@redhat.com) 6 * - Derived from NFS's sillyrename. 7 */ 8 9 #include <linux/kernel.h> 10 #include <linux/fs.h> 11 #include <linux/namei.h> 12 #include <linux/fsnotify.h> 13 #include "internal.h" 14 15 /* 16 * Actually perform the silly rename step. 17 */ 18 static int afs_do_silly_rename(struct afs_vnode *dvnode, struct afs_vnode *vnode, 19 struct dentry *old, struct dentry *new, 20 struct key *key) 21 { 22 struct afs_fs_cursor fc; 23 struct afs_status_cb *scb; 24 afs_dataversion_t dir_data_version; 25 int ret = -ERESTARTSYS; 26 27 _enter("%pd,%pd", old, new); 28 29 scb = kzalloc(sizeof(struct afs_status_cb), GFP_KERNEL); 30 if (!scb) 31 return -ENOMEM; 32 33 trace_afs_silly_rename(vnode, false); 34 if (afs_begin_vnode_operation(&fc, dvnode, key, true)) { 35 dir_data_version = dvnode->status.data_version + 1; 36 37 while (afs_select_fileserver(&fc)) { 38 fc.cb_break = afs_calc_vnode_cb_break(dvnode); 39 afs_fs_rename(&fc, old->d_name.name, 40 dvnode, new->d_name.name, 41 scb, scb); 42 } 43 44 afs_vnode_commit_status(&fc, dvnode, fc.cb_break, 45 &dir_data_version, scb); 46 ret = afs_end_vnode_operation(&fc); 47 } 48 49 if (ret == 0) { 50 spin_lock(&old->d_lock); 51 old->d_flags |= DCACHE_NFSFS_RENAMED; 52 spin_unlock(&old->d_lock); 53 if (dvnode->silly_key != key) { 54 key_put(dvnode->silly_key); 55 dvnode->silly_key = key_get(key); 56 } 57 58 down_write(&dvnode->validate_lock); 59 if (test_bit(AFS_VNODE_DIR_VALID, &dvnode->flags) && 60 dvnode->status.data_version == dir_data_version) { 61 afs_edit_dir_remove(dvnode, &old->d_name, 62 afs_edit_dir_for_silly_0); 63 afs_edit_dir_add(dvnode, &new->d_name, 64 &vnode->fid, afs_edit_dir_for_silly_1); 65 } 66 up_write(&dvnode->validate_lock); 67 } 68 69 kfree(scb); 70 _leave(" = %d", ret); 71 return ret; 72 } 73 74 /** 75 * afs_sillyrename - Perform a silly-rename of a dentry 76 * 77 * AFS is stateless and the server doesn't know when the client is holding a 78 * file open. To prevent application problems when a file is unlinked while 79 * it's still open, the client performs a "silly-rename". That is, it renames 80 * the file to a hidden file in the same directory, and only performs the 81 * unlink once the last reference to it is put. 82 * 83 * The final cleanup is done during dentry_iput. 84 */ 85 int afs_sillyrename(struct afs_vnode *dvnode, struct afs_vnode *vnode, 86 struct dentry *dentry, struct key *key) 87 { 88 static unsigned int sillycounter; 89 struct dentry *sdentry = NULL; 90 unsigned char silly[16]; 91 int ret = -EBUSY; 92 93 _enter(""); 94 95 /* We don't allow a dentry to be silly-renamed twice. */ 96 if (dentry->d_flags & DCACHE_NFSFS_RENAMED) 97 return -EBUSY; 98 99 sdentry = NULL; 100 do { 101 int slen; 102 103 dput(sdentry); 104 sillycounter++; 105 106 /* Create a silly name. Note that the ".__afs" prefix is 107 * understood by the salvager and must not be changed. 108 */ 109 slen = scnprintf(silly, sizeof(silly), ".__afs%04X", sillycounter); 110 sdentry = lookup_one_len(silly, dentry->d_parent, slen); 111 112 /* N.B. Better to return EBUSY here ... it could be dangerous 113 * to delete the file while it's in use. 114 */ 115 if (IS_ERR(sdentry)) 116 goto out; 117 } while (!d_is_negative(sdentry)); 118 119 ihold(&vnode->vfs_inode); 120 121 ret = afs_do_silly_rename(dvnode, vnode, dentry, sdentry, key); 122 switch (ret) { 123 case 0: 124 /* The rename succeeded. */ 125 d_move(dentry, sdentry); 126 break; 127 case -ERESTARTSYS: 128 /* The result of the rename is unknown. Play it safe by forcing 129 * a new lookup. 130 */ 131 d_drop(dentry); 132 d_drop(sdentry); 133 } 134 135 iput(&vnode->vfs_inode); 136 dput(sdentry); 137 out: 138 _leave(" = %d", ret); 139 return ret; 140 } 141 142 /* 143 * Tell the server to remove a sillyrename file. 144 */ 145 static int afs_do_silly_unlink(struct afs_vnode *dvnode, struct afs_vnode *vnode, 146 struct dentry *dentry, struct key *key) 147 { 148 struct afs_fs_cursor fc; 149 struct afs_status_cb *scb; 150 int ret = -ERESTARTSYS; 151 152 _enter(""); 153 154 scb = kcalloc(2, sizeof(struct afs_status_cb), GFP_KERNEL); 155 if (!scb) 156 return -ENOMEM; 157 158 trace_afs_silly_rename(vnode, true); 159 if (afs_begin_vnode_operation(&fc, dvnode, key, false)) { 160 afs_dataversion_t dir_data_version = dvnode->status.data_version + 1; 161 162 while (afs_select_fileserver(&fc)) { 163 fc.cb_break = afs_calc_vnode_cb_break(dvnode); 164 165 if (test_bit(AFS_SERVER_FL_IS_YFS, &fc.cbi->server->flags) && 166 !test_bit(AFS_SERVER_FL_NO_RM2, &fc.cbi->server->flags)) { 167 yfs_fs_remove_file2(&fc, vnode, dentry->d_name.name, 168 &scb[0], &scb[1]); 169 if (fc.ac.error != -ECONNABORTED || 170 fc.ac.abort_code != RXGEN_OPCODE) 171 continue; 172 set_bit(AFS_SERVER_FL_NO_RM2, &fc.cbi->server->flags); 173 } 174 175 afs_fs_remove(&fc, vnode, dentry->d_name.name, false, &scb[0]); 176 } 177 178 afs_vnode_commit_status(&fc, dvnode, fc.cb_break, 179 &dir_data_version, &scb[0]); 180 ret = afs_end_vnode_operation(&fc); 181 if (ret == 0) { 182 drop_nlink(&vnode->vfs_inode); 183 if (vnode->vfs_inode.i_nlink == 0) { 184 set_bit(AFS_VNODE_DELETED, &vnode->flags); 185 clear_bit(AFS_VNODE_CB_PROMISED, &vnode->flags); 186 } 187 } 188 if (ret == 0) { 189 down_write(&dvnode->validate_lock); 190 if (test_bit(AFS_VNODE_DIR_VALID, &dvnode->flags) && 191 dvnode->status.data_version == dir_data_version) 192 afs_edit_dir_remove(dvnode, &dentry->d_name, 193 afs_edit_dir_for_unlink); 194 up_write(&dvnode->validate_lock); 195 } 196 } 197 198 kfree(scb); 199 _leave(" = %d", ret); 200 return ret; 201 } 202 203 /* 204 * Remove sillyrename file on iput. 205 */ 206 int afs_silly_iput(struct dentry *dentry, struct inode *inode) 207 { 208 struct afs_vnode *dvnode = AFS_FS_I(d_inode(dentry->d_parent)); 209 struct afs_vnode *vnode = AFS_FS_I(inode); 210 struct dentry *alias; 211 int ret; 212 213 DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); 214 215 _enter("%p{%pd},%llx", dentry, dentry, vnode->fid.vnode); 216 217 down_read(&dvnode->rmdir_lock); 218 219 alias = d_alloc_parallel(dentry->d_parent, &dentry->d_name, &wq); 220 if (IS_ERR(alias)) { 221 up_read(&dvnode->rmdir_lock); 222 return 0; 223 } 224 225 if (!d_in_lookup(alias)) { 226 /* We raced with lookup... See if we need to transfer the 227 * sillyrename information to the aliased dentry. 228 */ 229 ret = 0; 230 spin_lock(&alias->d_lock); 231 if (d_really_is_positive(alias) && 232 !(alias->d_flags & DCACHE_NFSFS_RENAMED)) { 233 alias->d_flags |= DCACHE_NFSFS_RENAMED; 234 ret = 1; 235 } 236 spin_unlock(&alias->d_lock); 237 up_read(&dvnode->rmdir_lock); 238 dput(alias); 239 return ret; 240 } 241 242 /* Stop lock-release from complaining. */ 243 spin_lock(&vnode->lock); 244 vnode->lock_state = AFS_VNODE_LOCK_DELETED; 245 trace_afs_flock_ev(vnode, NULL, afs_flock_silly_delete, 0); 246 spin_unlock(&vnode->lock); 247 248 afs_do_silly_unlink(dvnode, vnode, dentry, dvnode->silly_key); 249 up_read(&dvnode->rmdir_lock); 250 d_lookup_done(alias); 251 dput(alias); 252 return 1; 253 } 254