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 static void afs_silly_rename_success(struct afs_operation *op) 16 { 17 _enter("op=%08x", op->debug_id); 18 19 afs_vnode_commit_status(op, &op->file[0]); 20 } 21 22 static void afs_silly_rename_edit_dir(struct afs_operation *op) 23 { 24 struct afs_vnode_param *dvp = &op->file[0]; 25 struct afs_vnode *dvnode = dvp->vnode; 26 struct afs_vnode *vnode = AFS_FS_I(d_inode(op->dentry)); 27 struct dentry *old = op->dentry; 28 struct dentry *new = op->dentry_2; 29 30 spin_lock(&old->d_lock); 31 old->d_flags |= DCACHE_NFSFS_RENAMED; 32 spin_unlock(&old->d_lock); 33 if (dvnode->silly_key != op->key) { 34 key_put(dvnode->silly_key); 35 dvnode->silly_key = key_get(op->key); 36 } 37 38 down_write(&dvnode->validate_lock); 39 if (test_bit(AFS_VNODE_DIR_VALID, &dvnode->flags) && 40 dvnode->status.data_version == dvp->dv_before + dvp->dv_delta) { 41 afs_edit_dir_remove(dvnode, &old->d_name, 42 afs_edit_dir_for_silly_0); 43 afs_edit_dir_add(dvnode, &new->d_name, 44 &vnode->fid, afs_edit_dir_for_silly_1); 45 } 46 up_write(&dvnode->validate_lock); 47 } 48 49 static const struct afs_operation_ops afs_silly_rename_operation = { 50 .issue_afs_rpc = afs_fs_rename, 51 .issue_yfs_rpc = yfs_fs_rename, 52 .success = afs_silly_rename_success, 53 .edit_dir = afs_silly_rename_edit_dir, 54 }; 55 56 /* 57 * Actually perform the silly rename step. 58 */ 59 static int afs_do_silly_rename(struct afs_vnode *dvnode, struct afs_vnode *vnode, 60 struct dentry *old, struct dentry *new, 61 struct key *key) 62 { 63 struct afs_operation *op; 64 65 _enter("%pd,%pd", old, new); 66 67 op = afs_alloc_operation(key, dvnode->volume); 68 if (IS_ERR(op)) 69 return PTR_ERR(op); 70 71 afs_op_set_vnode(op, 0, dvnode); 72 73 op->dentry = old; 74 op->dentry_2 = new; 75 op->ops = &afs_silly_rename_operation; 76 77 trace_afs_silly_rename(vnode, false); 78 return afs_do_sync_operation(op); 79 } 80 81 /** 82 * afs_sillyrename - Perform a silly-rename of a dentry 83 * 84 * AFS is stateless and the server doesn't know when the client is holding a 85 * file open. To prevent application problems when a file is unlinked while 86 * it's still open, the client performs a "silly-rename". That is, it renames 87 * the file to a hidden file in the same directory, and only performs the 88 * unlink once the last reference to it is put. 89 * 90 * The final cleanup is done during dentry_iput. 91 */ 92 int afs_sillyrename(struct afs_vnode *dvnode, struct afs_vnode *vnode, 93 struct dentry *dentry, struct key *key) 94 { 95 static unsigned int sillycounter; 96 struct dentry *sdentry = NULL; 97 unsigned char silly[16]; 98 int ret = -EBUSY; 99 100 _enter(""); 101 102 /* We don't allow a dentry to be silly-renamed twice. */ 103 if (dentry->d_flags & DCACHE_NFSFS_RENAMED) 104 return -EBUSY; 105 106 sdentry = NULL; 107 do { 108 int slen; 109 110 dput(sdentry); 111 sillycounter++; 112 113 /* Create a silly name. Note that the ".__afs" prefix is 114 * understood by the salvager and must not be changed. 115 */ 116 slen = scnprintf(silly, sizeof(silly), ".__afs%04X", sillycounter); 117 sdentry = lookup_one_len(silly, dentry->d_parent, slen); 118 119 /* N.B. Better to return EBUSY here ... it could be dangerous 120 * to delete the file while it's in use. 121 */ 122 if (IS_ERR(sdentry)) 123 goto out; 124 } while (!d_is_negative(sdentry)); 125 126 ihold(&vnode->vfs_inode); 127 128 ret = afs_do_silly_rename(dvnode, vnode, dentry, sdentry, key); 129 switch (ret) { 130 case 0: 131 /* The rename succeeded. */ 132 d_move(dentry, sdentry); 133 break; 134 case -ERESTARTSYS: 135 /* The result of the rename is unknown. Play it safe by forcing 136 * a new lookup. 137 */ 138 d_drop(dentry); 139 d_drop(sdentry); 140 } 141 142 iput(&vnode->vfs_inode); 143 dput(sdentry); 144 out: 145 _leave(" = %d", ret); 146 return ret; 147 } 148 149 static void afs_silly_unlink_success(struct afs_operation *op) 150 { 151 struct afs_vnode *vnode = op->file[1].vnode; 152 153 _enter("op=%08x", op->debug_id); 154 afs_check_for_remote_deletion(op, op->file[0].vnode); 155 afs_vnode_commit_status(op, &op->file[0]); 156 afs_vnode_commit_status(op, &op->file[1]); 157 afs_update_dentry_version(op, &op->file[0], op->dentry); 158 159 drop_nlink(&vnode->vfs_inode); 160 if (vnode->vfs_inode.i_nlink == 0) { 161 set_bit(AFS_VNODE_DELETED, &vnode->flags); 162 clear_bit(AFS_VNODE_CB_PROMISED, &vnode->flags); 163 } 164 } 165 166 static void afs_silly_unlink_edit_dir(struct afs_operation *op) 167 { 168 struct afs_vnode_param *dvp = &op->file[0]; 169 struct afs_vnode *dvnode = dvp->vnode; 170 171 _enter("op=%08x", op->debug_id); 172 down_write(&dvnode->validate_lock); 173 if (test_bit(AFS_VNODE_DIR_VALID, &dvnode->flags) && 174 dvnode->status.data_version == dvp->dv_before + dvp->dv_delta) 175 afs_edit_dir_remove(dvnode, &op->dentry->d_name, 176 afs_edit_dir_for_unlink); 177 up_write(&dvnode->validate_lock); 178 } 179 180 static const struct afs_operation_ops afs_silly_unlink_operation = { 181 .issue_afs_rpc = afs_fs_remove_file, 182 .issue_yfs_rpc = yfs_fs_remove_file, 183 .success = afs_silly_unlink_success, 184 .edit_dir = afs_silly_unlink_edit_dir, 185 }; 186 187 /* 188 * Tell the server to remove a sillyrename file. 189 */ 190 static int afs_do_silly_unlink(struct afs_vnode *dvnode, struct afs_vnode *vnode, 191 struct dentry *dentry, struct key *key) 192 { 193 struct afs_operation *op; 194 195 _enter(""); 196 197 op = afs_alloc_operation(NULL, dvnode->volume); 198 if (IS_ERR(op)) 199 return PTR_ERR(op); 200 201 afs_op_set_vnode(op, 0, dvnode); 202 afs_op_set_vnode(op, 1, vnode); 203 204 op->dentry = dentry; 205 op->ops = &afs_silly_unlink_operation; 206 207 trace_afs_silly_rename(vnode, true); 208 return afs_do_sync_operation(op); 209 } 210 211 /* 212 * Remove sillyrename file on iput. 213 */ 214 int afs_silly_iput(struct dentry *dentry, struct inode *inode) 215 { 216 struct afs_vnode *dvnode = AFS_FS_I(d_inode(dentry->d_parent)); 217 struct afs_vnode *vnode = AFS_FS_I(inode); 218 struct dentry *alias; 219 int ret; 220 221 DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); 222 223 _enter("%p{%pd},%llx", dentry, dentry, vnode->fid.vnode); 224 225 down_read(&dvnode->rmdir_lock); 226 227 alias = d_alloc_parallel(dentry->d_parent, &dentry->d_name, &wq); 228 if (IS_ERR(alias)) { 229 up_read(&dvnode->rmdir_lock); 230 return 0; 231 } 232 233 if (!d_in_lookup(alias)) { 234 /* We raced with lookup... See if we need to transfer the 235 * sillyrename information to the aliased dentry. 236 */ 237 ret = 0; 238 spin_lock(&alias->d_lock); 239 if (d_really_is_positive(alias) && 240 !(alias->d_flags & DCACHE_NFSFS_RENAMED)) { 241 alias->d_flags |= DCACHE_NFSFS_RENAMED; 242 ret = 1; 243 } 244 spin_unlock(&alias->d_lock); 245 up_read(&dvnode->rmdir_lock); 246 dput(alias); 247 return ret; 248 } 249 250 /* Stop lock-release from complaining. */ 251 spin_lock(&vnode->lock); 252 vnode->lock_state = AFS_VNODE_LOCK_DELETED; 253 trace_afs_flock_ev(vnode, NULL, afs_flock_silly_delete, 0); 254 spin_unlock(&vnode->lock); 255 256 afs_do_silly_unlink(dvnode, vnode, dentry, dvnode->silly_key); 257 up_read(&dvnode->rmdir_lock); 258 d_lookup_done(alias); 259 dput(alias); 260 return 1; 261 } 262