fs/afs/dir_silly.c

   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_check_dir_conflict(op, &op->file[0]);
  20         afs_vnode_commit_status(op, &op->file[0]);
  21 }
  22
  23 static void afs_silly_rename_edit_dir(struct afs_operation *op)
  24 {
  25         struct afs_vnode_param *dvp = &op->file[0];
  26         struct afs_vnode *dvnode = dvp->vnode;
  27         struct afs_vnode *vnode = AFS_FS_I(d_inode(op->dentry));
  28         struct dentry *old = op->dentry;
  29         struct dentry *new = op->dentry_2;
  30
  31         spin_lock(&old->d_lock);
  32         old->d_flags |= DCACHE_NFSFS_RENAMED;
  33         spin_unlock(&old->d_lock);
  34         if (dvnode->silly_key != op->key) {
  35                 key_put(dvnode->silly_key);
  36                 dvnode->silly_key = key_get(op->key);
  37         }
  38
  39         down_write(&dvnode->validate_lock);
  40         if (test_bit(AFS_VNODE_DIR_VALID, &dvnode->flags) &&
  41             dvnode->status.data_version == dvp->dv_before + dvp->dv_delta) {
  42                 afs_edit_dir_remove(dvnode, &old->d_name,
  43                                     afs_edit_dir_for_silly_0);
  44                 afs_edit_dir_add(dvnode, &new->d_name,
  45                                  &vnode->fid, afs_edit_dir_for_silly_1);
  46         }
  47         up_write(&dvnode->validate_lock);
  48 }
  49
  50 static const struct afs_operation_ops afs_silly_rename_operation = {
  51         .issue_afs_rpc  = afs_fs_rename,
  52         .issue_yfs_rpc  = yfs_fs_rename,
  53         .success        = afs_silly_rename_success,
  54         .edit_dir       = afs_silly_rename_edit_dir,
  55 };
  56
  57 /*
  58  * Actually perform the silly rename step.
  59  */
  60 static int afs_do_silly_rename(struct afs_vnode *dvnode, struct afs_vnode *vnode,
  61                                struct dentry *old, struct dentry *new,
  62                                struct key *key)
  63 {
  64         struct afs_operation *op;
  65
  66         _enter("%pd,%pd", old, new);
  67
  68         op = afs_alloc_operation(key, dvnode->volume);
  69         if (IS_ERR(op))
  70                 return PTR_ERR(op);
  71
  72         afs_op_set_vnode(op, 0, dvnode);
  73         afs_op_set_vnode(op, 1, dvnode);
  74         op->file[0].dv_delta = 1;
  75         op->file[1].dv_delta = 1;
  76         op->file[0].modification = true;
  77         op->file[1].modification = true;
  78         op->file[0].update_ctime = true;
  79         op->file[1].update_ctime = true;
  80
  81         op->dentry              = old;
  82         op->dentry_2            = new;
  83         op->ops                 = &afs_silly_rename_operation;
  84
  85         trace_afs_silly_rename(vnode, false);
  86         return afs_do_sync_operation(op);
  87 }
  88
  89 /*
  90  * Perform silly-rename of a dentry.
  91  *
  92  * AFS is stateless and the server doesn't know when the client is holding a
  93  * file open.  To prevent application problems when a file is unlinked while
  94  * it's still open, the client performs a "silly-rename".  That is, it renames
  95  * the file to a hidden file in the same directory, and only performs the
  96  * unlink once the last reference to it is put.
  97  *
  98  * The final cleanup is done during dentry_iput.
  99  */
 100 int afs_sillyrename(struct afs_vnode *dvnode, struct afs_vnode *vnode,
 101                     struct dentry *dentry, struct key *key)
 102 {
 103         static unsigned int sillycounter;
 104         struct dentry *sdentry = NULL;
 105         unsigned char silly[16];
 106         int ret = -EBUSY;
 107
 108         _enter("");
 109
 110         /* We don't allow a dentry to be silly-renamed twice. */
 111         if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
 112                 return -EBUSY;
 113
 114         sdentry = NULL;
 115         do {
 116                 int slen;
 117
 118                 dput(sdentry);
 119                 sillycounter++;
 120
 121                 /* Create a silly name.  Note that the ".__afs" prefix is
 122                  * understood by the salvager and must not be changed.
 123                  */
 124                 slen = scnprintf(silly, sizeof(silly), ".__afs%04X", sillycounter);
 125                 sdentry = lookup_one_len(silly, dentry->d_parent, slen);
 126
 127                 /* N.B. Better to return EBUSY here ... it could be dangerous
 128                  * to delete the file while it's in use.
 129                  */
 130                 if (IS_ERR(sdentry))
 131                         goto out;
 132         } while (!d_is_negative(sdentry));
 133
 134         ihold(&vnode->netfs.inode);
 135
 136         ret = afs_do_silly_rename(dvnode, vnode, dentry, sdentry, key);
 137         switch (ret) {
 138         case 0:
 139                 /* The rename succeeded. */
 140                 set_bit(AFS_VNODE_SILLY_DELETED, &vnode->flags);
 141                 d_move(dentry, sdentry);
 142                 break;
 143         case -ERESTARTSYS:
 144                 /* The result of the rename is unknown. Play it safe by forcing
 145                  * a new lookup.
 146                  */
 147                 d_drop(dentry);
 148                 d_drop(sdentry);
 149         }
 150
 151         iput(&vnode->netfs.inode);
 152         dput(sdentry);
 153 out:
 154         _leave(" = %d", ret);
 155         return ret;
 156 }
 157
 158 static void afs_silly_unlink_success(struct afs_operation *op)
 159 {
 160         _enter("op=%08x", op->debug_id);
 161         afs_check_dir_conflict(op, &op->file[0]);
 162         afs_vnode_commit_status(op, &op->file[0]);
 163         afs_vnode_commit_status(op, &op->file[1]);
 164         afs_update_dentry_version(op, &op->file[0], op->dentry);
 165 }
 166
 167 static void afs_silly_unlink_edit_dir(struct afs_operation *op)
 168 {
 169         struct afs_vnode_param *dvp = &op->file[0];
 170         struct afs_vnode *dvnode = dvp->vnode;
 171
 172         _enter("op=%08x", op->debug_id);
 173         down_write(&dvnode->validate_lock);
 174         if (test_bit(AFS_VNODE_DIR_VALID, &dvnode->flags) &&
 175             dvnode->status.data_version == dvp->dv_before + dvp->dv_delta)
 176                 afs_edit_dir_remove(dvnode, &op->dentry->d_name,
 177                                     afs_edit_dir_for_unlink);
 178         up_write(&dvnode->validate_lock);
 179 }
 180
 181 static const struct afs_operation_ops afs_silly_unlink_operation = {
 182         .issue_afs_rpc  = afs_fs_remove_file,
 183         .issue_yfs_rpc  = yfs_fs_remove_file,
 184         .success        = afs_silly_unlink_success,
 185         .aborted        = afs_check_for_remote_deletion,
 186         .edit_dir       = afs_silly_unlink_edit_dir,
 187 };
 188
 189 /*
 190  * Tell the server to remove a sillyrename file.
 191  */
 192 static int afs_do_silly_unlink(struct afs_vnode *dvnode, struct afs_vnode *vnode,
 193                                struct dentry *dentry, struct key *key)
 194 {
 195         struct afs_operation *op;
 196
 197         _enter("");
 198
 199         op = afs_alloc_operation(NULL, dvnode->volume);
 200         if (IS_ERR(op))
 201                 return PTR_ERR(op);
 202
 203         afs_op_set_vnode(op, 0, dvnode);
 204         afs_op_set_vnode(op, 1, vnode);
 205         op->file[0].dv_delta = 1;
 206         op->file[0].modification = true;
 207         op->file[0].update_ctime = true;
 208         op->file[1].op_unlinked = true;
 209         op->file[1].update_ctime = true;
 210
 211         op->dentry      = dentry;
 212         op->ops         = &afs_silly_unlink_operation;
 213
 214         trace_afs_silly_rename(vnode, true);
 215         afs_begin_vnode_operation(op);
 216         afs_wait_for_operation(op);
 217
 218         /* If there was a conflict with a third party, check the status of the
 219          * unlinked vnode.
 220          */
 221         if (op->cumul_error.error == 0 && (op->flags & AFS_OPERATION_DIR_CONFLICT)) {
 222                 op->file[1].update_ctime = false;
 223                 op->fetch_status.which = 1;
 224                 op->ops = &afs_fetch_status_operation;
 225                 afs_begin_vnode_operation(op);
 226                 afs_wait_for_operation(op);
 227         }
 228
 229         return afs_put_operation(op);
 230 }
 231
 232 /*
 233  * Remove sillyrename file on iput.
 234  */
 235 int afs_silly_iput(struct dentry *dentry, struct inode *inode)
 236 {
 237         struct afs_vnode *dvnode = AFS_FS_I(d_inode(dentry->d_parent));
 238         struct afs_vnode *vnode = AFS_FS_I(inode);
 239         struct dentry *alias;
 240         int ret;
 241
 242         DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
 243
 244         _enter("%p{%pd},%llx", dentry, dentry, vnode->fid.vnode);
 245
 246         down_read(&dvnode->rmdir_lock);
 247
 248         alias = d_alloc_parallel(dentry->d_parent, &dentry->d_name, &wq);
 249         if (IS_ERR(alias)) {
 250                 up_read(&dvnode->rmdir_lock);
 251                 return 0;
 252         }
 253
 254         if (!d_in_lookup(alias)) {
 255                 /* We raced with lookup...  See if we need to transfer the
 256                  * sillyrename information to the aliased dentry.
 257                  */
 258                 ret = 0;
 259                 spin_lock(&alias->d_lock);
 260                 if (d_really_is_positive(alias) &&
 261                     !(alias->d_flags & DCACHE_NFSFS_RENAMED)) {
 262                         alias->d_flags |= DCACHE_NFSFS_RENAMED;
 263                         ret = 1;
 264                 }
 265                 spin_unlock(&alias->d_lock);
 266                 up_read(&dvnode->rmdir_lock);
 267                 dput(alias);
 268                 return ret;
 269         }
 270
 271         /* Stop lock-release from complaining. */
 272         spin_lock(&vnode->lock);
 273         vnode->lock_state = AFS_VNODE_LOCK_DELETED;
 274         trace_afs_flock_ev(vnode, NULL, afs_flock_silly_delete, 0);
 275         spin_unlock(&vnode->lock);
 276
 277         afs_do_silly_unlink(dvnode, vnode, dentry, dvnode->silly_key);
 278         up_read(&dvnode->rmdir_lock);
 279         d_lookup_done(alias);
 280         dput(alias);
 281         return 1;
 282 }