[linux-2.6-block.git] / fs / afs / dir_silly.c

// SPDX-License-Identifier: GPL-2.0-or-later
/* AFS silly rename handling
 *
 * Copyright (C) 2019 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 * - Derived from NFS's sillyrename.
 */

#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/namei.h>
#include <linux/fsnotify.h>
#include "internal.h"

static void afs_silly_rename_success(struct afs_operation *op)
{
	_enter("op=%08x", op->debug_id);

	afs_vnode_commit_status(op, &op->file[0]);
}

static void afs_silly_rename_edit_dir(struct afs_operation *op)
{
	struct afs_vnode_param *dvp = &op->file[0];
	struct afs_vnode *dvnode = dvp->vnode;
	struct afs_vnode *vnode = AFS_FS_I(d_inode(op->dentry));
	struct dentry *old = op->dentry;
	struct dentry *new = op->dentry_2;

	spin_lock(&old->d_lock);
	old->d_flags |= DCACHE_NFSFS_RENAMED;
	spin_unlock(&old->d_lock);
	if (dvnode->silly_key != op->key) {
		key_put(dvnode->silly_key);
		dvnode->silly_key = key_get(op->key);
	}

	down_write(&dvnode->validate_lock);
	if (test_bit(AFS_VNODE_DIR_VALID, &dvnode->flags) &&
	    dvnode->status.data_version == dvp->dv_before + dvp->dv_delta) {
		afs_edit_dir_remove(dvnode, &old->d_name,
				    afs_edit_dir_for_silly_0);
		afs_edit_dir_add(dvnode, &new->d_name,
				 &vnode->fid, afs_edit_dir_for_silly_1);
	}
	up_write(&dvnode->validate_lock);
}

static const struct afs_operation_ops afs_silly_rename_operation = {
	.issue_afs_rpc	= afs_fs_rename,
	.issue_yfs_rpc	= yfs_fs_rename,
	.success	= afs_silly_rename_success,
	.edit_dir	= afs_silly_rename_edit_dir,
};

/*
 * Actually perform the silly rename step.
 */
static int afs_do_silly_rename(struct afs_vnode *dvnode, struct afs_vnode *vnode,
			       struct dentry *old, struct dentry *new,
			       struct key *key)
{
	struct afs_operation *op;

	_enter("%pd,%pd", old, new);

	op = afs_alloc_operation(key, dvnode->volume);
	if (IS_ERR(op))
		return PTR_ERR(op);

	afs_op_set_vnode(op, 0, dvnode);

	op->dentry		= old;
	op->dentry_2		= new;
	op->ops			= &afs_silly_rename_operation;

	trace_afs_silly_rename(vnode, false);
	return afs_do_sync_operation(op);
}

/**
 * afs_sillyrename - Perform a silly-rename of a dentry
 *
 * AFS is stateless and the server doesn't know when the client is holding a
 * file open.  To prevent application problems when a file is unlinked while
 * it's still open, the client performs a "silly-rename".  That is, it renames
 * the file to a hidden file in the same directory, and only performs the
 * unlink once the last reference to it is put.
 *
 * The final cleanup is done during dentry_iput.
 */
int afs_sillyrename(struct afs_vnode *dvnode, struct afs_vnode *vnode,
		    struct dentry *dentry, struct key *key)
{
	static unsigned int sillycounter;
	struct dentry *sdentry = NULL;
	unsigned char silly[16];
	int ret = -EBUSY;

	_enter("");

	/* We don't allow a dentry to be silly-renamed twice. */
	if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
		return -EBUSY;

	sdentry = NULL;
	do {
		int slen;

		dput(sdentry);
		sillycounter++;

		/* Create a silly name.  Note that the ".__afs" prefix is
		 * understood by the salvager and must not be changed.
		 */
		slen = scnprintf(silly, sizeof(silly), ".__afs%04X", sillycounter);
		sdentry = lookup_one_len(silly, dentry->d_parent, slen);

		/* N.B. Better to return EBUSY here ... it could be dangerous
		 * to delete the file while it's in use.
		 */
		if (IS_ERR(sdentry))
			goto out;
	} while (!d_is_negative(sdentry));

	ihold(&vnode->vfs_inode);

	ret = afs_do_silly_rename(dvnode, vnode, dentry, sdentry, key);
	switch (ret) {
	case 0:
		/* The rename succeeded. */
		d_move(dentry, sdentry);
		break;
	case -ERESTARTSYS:
		/* The result of the rename is unknown. Play it safe by forcing
		 * a new lookup.
		 */
		d_drop(dentry);
		d_drop(sdentry);
	}

	iput(&vnode->vfs_inode);
	dput(sdentry);
out:
	_leave(" = %d", ret);
	return ret;
}

static void afs_silly_unlink_success(struct afs_operation *op)
{
	struct afs_vnode *vnode = op->file[1].vnode;

	_enter("op=%08x", op->debug_id);
	afs_check_for_remote_deletion(op, op->file[0].vnode);
	afs_vnode_commit_status(op, &op->file[0]);
	afs_vnode_commit_status(op, &op->file[1]);
	afs_update_dentry_version(op, &op->file[0], op->dentry);

	drop_nlink(&vnode->vfs_inode);
	if (vnode->vfs_inode.i_nlink == 0) {
		set_bit(AFS_VNODE_DELETED, &vnode->flags);
		clear_bit(AFS_VNODE_CB_PROMISED, &vnode->flags);
	}
}

static void afs_silly_unlink_edit_dir(struct afs_operation *op)
{
	struct afs_vnode_param *dvp = &op->file[0];
	struct afs_vnode *dvnode = dvp->vnode;

	_enter("op=%08x", op->debug_id);
	down_write(&dvnode->validate_lock);
	if (test_bit(AFS_VNODE_DIR_VALID, &dvnode->flags) &&
	    dvnode->status.data_version == dvp->dv_before + dvp->dv_delta)
		afs_edit_dir_remove(dvnode, &op->dentry->d_name,
				    afs_edit_dir_for_unlink);
	up_write(&dvnode->validate_lock);
}

static const struct afs_operation_ops afs_silly_unlink_operation = {
	.issue_afs_rpc	= afs_fs_remove_file,
	.issue_yfs_rpc	= yfs_fs_remove_file,
	.success	= afs_silly_unlink_success,
	.edit_dir	= afs_silly_unlink_edit_dir,
};

/*
 * Tell the server to remove a sillyrename file.
 */
static int afs_do_silly_unlink(struct afs_vnode *dvnode, struct afs_vnode *vnode,
			       struct dentry *dentry, struct key *key)
{
	struct afs_operation *op;

	_enter("");

	op = afs_alloc_operation(NULL, dvnode->volume);
	if (IS_ERR(op))
		return PTR_ERR(op);

	afs_op_set_vnode(op, 0, dvnode);
	afs_op_set_vnode(op, 1, vnode);

	op->dentry	= dentry;
	op->ops		= &afs_silly_unlink_operation;

	trace_afs_silly_rename(vnode, true);
	return afs_do_sync_operation(op);
}

/*
 * Remove sillyrename file on iput.
 */
int afs_silly_iput(struct dentry *dentry, struct inode *inode)
{
	struct afs_vnode *dvnode = AFS_FS_I(d_inode(dentry->d_parent));
	struct afs_vnode *vnode = AFS_FS_I(inode);
	struct dentry *alias;
	int ret;

	DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);

	_enter("%p{%pd},%llx", dentry, dentry, vnode->fid.vnode);

	down_read(&dvnode->rmdir_lock);

	alias = d_alloc_parallel(dentry->d_parent, &dentry->d_name, &wq);
	if (IS_ERR(alias)) {
		up_read(&dvnode->rmdir_lock);
		return 0;
	}

	if (!d_in_lookup(alias)) {
		/* We raced with lookup...  See if we need to transfer the
		 * sillyrename information to the aliased dentry.
		 */
		ret = 0;
		spin_lock(&alias->d_lock);
		if (d_really_is_positive(alias) &&
		    !(alias->d_flags & DCACHE_NFSFS_RENAMED)) {
			alias->d_flags |= DCACHE_NFSFS_RENAMED;
			ret = 1;
		}
		spin_unlock(&alias->d_lock);
		up_read(&dvnode->rmdir_lock);
		dput(alias);
		return ret;
	}

	/* Stop lock-release from complaining. */
	spin_lock(&vnode->lock);
	vnode->lock_state = AFS_VNODE_LOCK_DELETED;
	trace_afs_flock_ev(vnode, NULL, afs_flock_silly_delete, 0);
	spin_unlock(&vnode->lock);

	afs_do_silly_unlink(dvnode, vnode, dentry, dvnode->silly_key);
	up_read(&dvnode->rmdir_lock);
	d_lookup_done(alias);
	dput(alias);
	return 1;
}
Commit	Line	Data
b4d0d230	1	// SPDX-License-Identifier: GPL-2.0-or-later
79ddbfa5 DH	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.
79ddbfa5 DH	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
e49c7b2f DH	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
79ddbfa5 DH	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	{
e49c7b2f	63	struct afs_operation *op;
79ddbfa5 DH	64
	65	_enter("%pd,%pd", old, new);
	66
e49c7b2f DH	67	op = afs_alloc_operation(key, dvnode->volume);
	68	if (IS_ERR(op))
	69	return PTR_ERR(op);
a58823ac	70
e49c7b2f	71	afs_op_set_vnode(op, 0, dvnode);
79ddbfa5	72
e49c7b2f DH	73	op->dentry = old;
	74	op->dentry_2 = new;
	75	op->ops = &afs_silly_rename_operation;
79ddbfa5	76
e49c7b2f DH	77	trace_afs_silly_rename(vnode, false);
e49c7b2f DH	78	return afs_do_sync_operation(op);
79ddbfa5 DH	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
e49c7b2f DH	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
79ddbfa5 DH	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	{
e49c7b2f	193	struct afs_operation *op;
79ddbfa5 DH	194
	195	_enter("");
	196
e49c7b2f DH	197	op = afs_alloc_operation(NULL, dvnode->volume);
	198	if (IS_ERR(op))
	199	return PTR_ERR(op);
a58823ac	200
e49c7b2f DH	201	afs_op_set_vnode(op, 0, dvnode);
e49c7b2f DH	202	afs_op_set_vnode(op, 1, vnode);
79ddbfa5	203
e49c7b2f DH	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);
79ddbfa5 DH	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	}