// SPDX-License-Identifier: GPL-2.0-or-later
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/* AFS silly rename handling
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*
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* Copyright (C) 2019 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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* - Derived from NFS's sillyrename.
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*/
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#include <linux/kernel.h>
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#include <linux/fs.h>
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#include <linux/namei.h>
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#include <linux/fsnotify.h>
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#include "internal.h"
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static void afs_silly_rename_success(struct afs_operation *op)
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{
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_enter("op=%08x", op->debug_id);
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afs_check_dir_conflict(op, &op->file[0]);
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afs_vnode_commit_status(op, &op->file[0]);
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}
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static void afs_silly_rename_edit_dir(struct afs_operation *op)
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{
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struct afs_vnode_param *dvp = &op->file[0];
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struct afs_vnode *dvnode = dvp->vnode;
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struct afs_vnode *vnode = AFS_FS_I(d_inode(op->dentry));
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struct dentry *old = op->dentry;
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struct dentry *new = op->dentry_2;
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spin_lock(&old->d_lock);
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old->d_flags |= DCACHE_NFSFS_RENAMED;
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spin_unlock(&old->d_lock);
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if (dvnode->silly_key != op->key) {
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key_put(dvnode->silly_key);
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dvnode->silly_key = key_get(op->key);
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}
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down_write(&dvnode->validate_lock);
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if (test_bit(AFS_VNODE_DIR_VALID, &dvnode->flags) &&
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dvnode->status.data_version == dvp->dv_before + dvp->dv_delta) {
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afs_edit_dir_remove(dvnode, &old->d_name,
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afs_edit_dir_for_silly_0);
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afs_edit_dir_add(dvnode, &new->d_name,
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&vnode->fid, afs_edit_dir_for_silly_1);
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}
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up_write(&dvnode->validate_lock);
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}
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static const struct afs_operation_ops afs_silly_rename_operation = {
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.issue_afs_rpc = afs_fs_rename,
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.issue_yfs_rpc = yfs_fs_rename,
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.success = afs_silly_rename_success,
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.edit_dir = afs_silly_rename_edit_dir,
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};
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/*
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* Actually perform the silly rename step.
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*/
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static int afs_do_silly_rename(struct afs_vnode *dvnode, struct afs_vnode *vnode,
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struct dentry *old, struct dentry *new,
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struct key *key)
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{
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struct afs_operation *op;
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_enter("%pd,%pd", old, new);
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op = afs_alloc_operation(key, dvnode->volume);
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if (IS_ERR(op))
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return PTR_ERR(op);
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afs_op_set_vnode(op, 0, dvnode);
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afs_op_set_vnode(op, 1, dvnode);
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op->file[0].dv_delta = 1;
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op->file[1].dv_delta = 1;
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op->file[0].modification = true;
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op->file[1].modification = true;
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op->file[0].update_ctime = true;
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op->file[1].update_ctime = true;
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op->dentry = old;
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op->dentry_2 = new;
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op->ops = &afs_silly_rename_operation;
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trace_afs_silly_rename(vnode, false);
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return afs_do_sync_operation(op);
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}
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/**
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* afs_sillyrename - Perform a silly-rename of a dentry
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*
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* AFS is stateless and the server doesn't know when the client is holding a
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* file open. To prevent application problems when a file is unlinked while
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* it's still open, the client performs a "silly-rename". That is, it renames
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* the file to a hidden file in the same directory, and only performs the
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* unlink once the last reference to it is put.
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*
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* The final cleanup is done during dentry_iput.
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*/
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int afs_sillyrename(struct afs_vnode *dvnode, struct afs_vnode *vnode,
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struct dentry *dentry, struct key *key)
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{
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static unsigned int sillycounter;
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struct dentry *sdentry = NULL;
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unsigned char silly[16];
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int ret = -EBUSY;
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_enter("");
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/* We don't allow a dentry to be silly-renamed twice. */
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if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
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return -EBUSY;
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sdentry = NULL;
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do {
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int slen;
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dput(sdentry);
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sillycounter++;
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/* Create a silly name. Note that the ".__afs" prefix is
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* understood by the salvager and must not be changed.
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*/
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slen = scnprintf(silly, sizeof(silly), ".__afs%04X", sillycounter);
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sdentry = lookup_one_len(silly, dentry->d_parent, slen);
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/* N.B. Better to return EBUSY here ... it could be dangerous
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* to delete the file while it's in use.
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*/
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if (IS_ERR(sdentry))
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goto out;
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} while (!d_is_negative(sdentry));
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ihold(&vnode->vfs_inode);
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ret = afs_do_silly_rename(dvnode, vnode, dentry, sdentry, key);
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switch (ret) {
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case 0:
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/* The rename succeeded. */
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set_bit(AFS_VNODE_SILLY_DELETED, &vnode->flags);
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d_move(dentry, sdentry);
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break;
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case -ERESTARTSYS:
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/* The result of the rename is unknown. Play it safe by forcing
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* a new lookup.
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*/
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d_drop(dentry);
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d_drop(sdentry);
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}
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iput(&vnode->vfs_inode);
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dput(sdentry);
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out:
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_leave(" = %d", ret);
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return ret;
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}
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static void afs_silly_unlink_success(struct afs_operation *op)
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{
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_enter("op=%08x", op->debug_id);
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afs_check_dir_conflict(op, &op->file[0]);
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afs_vnode_commit_status(op, &op->file[0]);
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afs_vnode_commit_status(op, &op->file[1]);
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afs_update_dentry_version(op, &op->file[0], op->dentry);
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}
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static void afs_silly_unlink_edit_dir(struct afs_operation *op)
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{
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struct afs_vnode_param *dvp = &op->file[0];
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struct afs_vnode *dvnode = dvp->vnode;
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_enter("op=%08x", op->debug_id);
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down_write(&dvnode->validate_lock);
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if (test_bit(AFS_VNODE_DIR_VALID, &dvnode->flags) &&
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dvnode->status.data_version == dvp->dv_before + dvp->dv_delta)
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afs_edit_dir_remove(dvnode, &op->dentry->d_name,
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afs_edit_dir_for_unlink);
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up_write(&dvnode->validate_lock);
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}
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static const struct afs_operation_ops afs_silly_unlink_operation = {
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.issue_afs_rpc = afs_fs_remove_file,
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.issue_yfs_rpc = yfs_fs_remove_file,
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.success = afs_silly_unlink_success,
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.aborted = afs_check_for_remote_deletion,
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.edit_dir = afs_silly_unlink_edit_dir,
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};
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/*
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* Tell the server to remove a sillyrename file.
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*/
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static int afs_do_silly_unlink(struct afs_vnode *dvnode, struct afs_vnode *vnode,
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struct dentry *dentry, struct key *key)
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{
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struct afs_operation *op;
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_enter("");
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op = afs_alloc_operation(NULL, dvnode->volume);
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if (IS_ERR(op))
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return PTR_ERR(op);
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afs_op_set_vnode(op, 0, dvnode);
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afs_op_set_vnode(op, 1, vnode);
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op->file[0].dv_delta = 1;
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op->file[0].modification = true;
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op->file[0].update_ctime = true;
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op->file[1].op_unlinked = true;
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op->file[1].update_ctime = true;
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op->dentry = dentry;
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op->ops = &afs_silly_unlink_operation;
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trace_afs_silly_rename(vnode, true);
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afs_begin_vnode_operation(op);
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afs_wait_for_operation(op);
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/* If there was a conflict with a third party, check the status of the
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* unlinked vnode.
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*/
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if (op->error == 0 && (op->flags & AFS_OPERATION_DIR_CONFLICT)) {
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op->file[1].update_ctime = false;
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op->fetch_status.which = 1;
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op->ops = &afs_fetch_status_operation;
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afs_begin_vnode_operation(op);
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afs_wait_for_operation(op);
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}
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return afs_put_operation(op);
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}
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/*
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* Remove sillyrename file on iput.
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*/
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int afs_silly_iput(struct dentry *dentry, struct inode *inode)
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{
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struct afs_vnode *dvnode = AFS_FS_I(d_inode(dentry->d_parent));
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struct afs_vnode *vnode = AFS_FS_I(inode);
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struct dentry *alias;
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int ret;
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DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
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_enter("%p{%pd},%llx", dentry, dentry, vnode->fid.vnode);
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down_read(&dvnode->rmdir_lock);
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alias = d_alloc_parallel(dentry->d_parent, &dentry->d_name, &wq);
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if (IS_ERR(alias)) {
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up_read(&dvnode->rmdir_lock);
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return 0;
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}
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if (!d_in_lookup(alias)) {
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/* We raced with lookup... See if we need to transfer the
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* sillyrename information to the aliased dentry.
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*/
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ret = 0;
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spin_lock(&alias->d_lock);
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if (d_really_is_positive(alias) &&
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!(alias->d_flags & DCACHE_NFSFS_RENAMED)) {
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alias->d_flags |= DCACHE_NFSFS_RENAMED;
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ret = 1;
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}
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spin_unlock(&alias->d_lock);
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up_read(&dvnode->rmdir_lock);
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dput(alias);
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return ret;
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}
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/* Stop lock-release from complaining. */
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spin_lock(&vnode->lock);
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vnode->lock_state = AFS_VNODE_LOCK_DELETED;
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trace_afs_flock_ev(vnode, NULL, afs_flock_silly_delete, 0);
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spin_unlock(&vnode->lock);
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afs_do_silly_unlink(dvnode, vnode, dentry, dvnode->silly_key);
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up_read(&dvnode->rmdir_lock);
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d_lookup_done(alias);
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dput(alias);
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return 1;
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}
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