linux/fs/nfs/unlink.c

// SPDX-License-Identifier: GPL-2.0
/*
 *  linux/fs/nfs/unlink.c
 *
 * nfs sillydelete handling
 *
 */

#include <linux/slab.h>
#include <linux/string.h>
#include <linux/dcache.h>
#include <linux/sunrpc/sched.h>
#include <linux/sunrpc/clnt.h>
#include <linux/nfs_fs.h>
#include <linux/sched.h>
#include <linux/wait.h>
#include <linux/namei.h>
#include <linux/fsnotify.h>

#include "internal.h"
#include "nfs4_fs.h"
#include "iostat.h"
#include "delegation.h"

#include "nfstrace.h"

/**
 * nfs_free_unlinkdata - release data from a sillydelete operation.
 * @data: pointer to unlink structure.
 */
static void
nfs_free_unlinkdata(struct nfs_unlinkdata *data)
{ … }

/**
 * nfs_async_unlink_done - Sillydelete post-processing
 * @task: rpc_task of the sillydelete
 * @calldata: pointer to nfs_unlinkdata
 *
 * Do the directory attribute update.
 */
static void nfs_async_unlink_done(struct rpc_task *task, void *calldata)
{ … }

/**
 * nfs_async_unlink_release - Release the sillydelete data.
 * @calldata: struct nfs_unlinkdata to release
 *
 * We need to call nfs_put_unlinkdata as a 'tk_release' task since the
 * rpc_task would be freed too.
 */
static void nfs_async_unlink_release(void *calldata)
{ … }

static void nfs_unlink_prepare(struct rpc_task *task, void *calldata)
{ … }

static const struct rpc_call_ops nfs_unlink_ops = …;

static void nfs_do_call_unlink(struct inode *inode, struct nfs_unlinkdata *data)
{ … }

static int nfs_call_unlink(struct dentry *dentry, struct inode *inode, struct nfs_unlinkdata *data)
{ … }

/**
 * nfs_async_unlink - asynchronous unlinking of a file
 * @dentry: parent directory of dentry
 * @name: name of dentry to unlink
 */
static int
nfs_async_unlink(struct dentry *dentry, const struct qstr *name)
{ … }

/**
 * nfs_complete_unlink - Initialize completion of the sillydelete
 * @dentry: dentry to delete
 * @inode: inode
 *
 * Since we're most likely to be called by dentry_iput(), we
 * only use the dentry to find the sillydelete. We then copy the name
 * into the qstr.
 */
void
nfs_complete_unlink(struct dentry *dentry, struct inode *inode)
{ … }

/* Cancel a queued async unlink. Called when a sillyrename run fails. */
static void
nfs_cancel_async_unlink(struct dentry *dentry)
{ … }

/**
 * nfs_async_rename_done - Sillyrename post-processing
 * @task: rpc_task of the sillyrename
 * @calldata: nfs_renamedata for the sillyrename
 *
 * Do the directory attribute updates and the d_move
 */
static void nfs_async_rename_done(struct rpc_task *task, void *calldata)
{ … }

/**
 * nfs_async_rename_release - Release the sillyrename data.
 * @calldata: the struct nfs_renamedata to be released
 */
static void nfs_async_rename_release(void *calldata)
{ … }

static void nfs_rename_prepare(struct rpc_task *task, void *calldata)
{ … }

static const struct rpc_call_ops nfs_rename_ops = …;

/**
 * nfs_async_rename - perform an asynchronous rename operation
 * @old_dir: directory that currently holds the dentry to be renamed
 * @new_dir: target directory for the rename
 * @old_dentry: original dentry to be renamed
 * @new_dentry: dentry to which the old_dentry should be renamed
 * @complete: Function to run on successful completion
 *
 * It's expected that valid references to the dentries and inodes are held
 */
struct rpc_task *
nfs_async_rename(struct inode *old_dir, struct inode *new_dir,
		 struct dentry *old_dentry, struct dentry *new_dentry,
		 void (*complete)(struct rpc_task *, struct nfs_renamedata *))
{ … }

/*
 * Perform tasks needed when a sillyrename is done such as cancelling the
 * queued async unlink if it failed.
 */
static void
nfs_complete_sillyrename(struct rpc_task *task, struct nfs_renamedata *data)
{ … }

#define SILLYNAME_PREFIX …
#define SILLYNAME_PREFIX_LEN …
#define SILLYNAME_FILEID_LEN …
#define SILLYNAME_COUNTER_LEN …
#define SILLYNAME_LEN …

/**
 * nfs_sillyrename - Perform a silly-rename of a dentry
 * @dir: inode of directory that contains dentry
 * @dentry: dentry to be sillyrenamed
 *
 * NFSv2/3 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.
 *
 * (Note: NFSv4 is stateful, and has opens, so in theory an NFSv4 server
 * could take responsibility for keeping open files referenced.  The server
 * would also need to ensure that opened-but-deleted files were kept over
 * reboots.  However, we may not assume a server does so.  (RFC 5661
 * does provide an OPEN4_RESULT_PRESERVE_UNLINKED flag that a server can
 * use to advertise that it does this; some day we may take advantage of
 * it.))
 */
int
nfs_sillyrename(struct inode *dir, struct dentry *dentry)
{ … }