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