unlink.c

Go to the documentation of this file.

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

static void
nfs_free_unlinkdata(struct nfs_unlinkdata *data)
{
    iput(data->dir);
    put_rpccred(data->cred);
    kfree(data->args.name.name);
    kfree(data);
}

#define NAME_ALLOC_LEN(len) ((len+16) & ~15)

static int nfs_copy_dname(struct dentry *dentry, struct nfs_unlinkdata *data)
{
    char        *str;
    int     len = dentry->d_name.len;

    str = kmemdup(dentry->d_name.name, NAME_ALLOC_LEN(len), GFP_KERNEL);
    if (!str)
        return -ENOMEM;
    data->args.name.len = len;
    data->args.name.name = str;
    return 0;
}

static void nfs_free_dname(struct nfs_unlinkdata *data)
{
    kfree(data->args.name.name);
    data->args.name.name = NULL;
    data->args.name.len = 0;
}

static void nfs_dec_sillycount(struct inode *dir)
{
    struct nfs_inode *nfsi = NFS_I(dir);
    if (atomic_dec_return(&nfsi->silly_count) == 1)
        wake_up(&nfsi->waitqueue);
}

static void nfs_async_unlink_done(struct rpc_task *task, void *calldata)
{
    struct nfs_unlinkdata *data = calldata;
    struct inode *dir = data->dir;

    if (!NFS_PROTO(dir)->unlink_done(task, dir))
        rpc_restart_call_prepare(task);
}

static void nfs_async_unlink_release(void *calldata)
{
    struct nfs_unlinkdata   *data = calldata;
    struct super_block *sb = data->dir->i_sb;

    nfs_dec_sillycount(data->dir);
    nfs_free_unlinkdata(data);
    nfs_sb_deactive_async(sb);
}

static void nfs_unlink_prepare(struct rpc_task *task, void *calldata)
{
    struct nfs_unlinkdata *data = calldata;
    NFS_PROTO(data->dir)->unlink_rpc_prepare(task, data);
}

static const struct rpc_call_ops nfs_unlink_ops = {
    .rpc_call_done = nfs_async_unlink_done,
    .rpc_release = nfs_async_unlink_release,
    .rpc_call_prepare = nfs_unlink_prepare,
};

static int nfs_do_call_unlink(struct dentry *parent, struct inode *dir, struct nfs_unlinkdata *data)
{
    struct rpc_message msg = {
        .rpc_argp = &data->args,
        .rpc_resp = &data->res,
        .rpc_cred = data->cred,
    };
    struct rpc_task_setup task_setup_data = {
        .rpc_message = &msg,
        .callback_ops = &nfs_unlink_ops,
        .callback_data = data,
        .workqueue = nfsiod_workqueue,
        .flags = RPC_TASK_ASYNC,
    };
    struct rpc_task *task;
    struct dentry *alias;

    alias = d_lookup(parent, &data->args.name);
    if (alias != NULL) {
        int ret;
        void *devname_garbage = NULL;

        /*
         * Hey, we raced with lookup... See if we need to transfer
         * the sillyrename information to the aliased dentry.
         */
        nfs_free_dname(data);
        ret = nfs_copy_dname(alias, data);
        spin_lock(&alias->d_lock);
        if (ret == 0 && alias->d_inode != NULL &&
            !(alias->d_flags & DCACHE_NFSFS_RENAMED)) {
            devname_garbage = alias->d_fsdata;
            alias->d_fsdata = data;
            alias->d_flags |= DCACHE_NFSFS_RENAMED;
            ret = 1;
        } else
            ret = 0;
        spin_unlock(&alias->d_lock);
        nfs_dec_sillycount(dir);
        dput(alias);
        /*
         * If we'd displaced old cached devname, free it.  At that
         * point dentry is definitely not a root, so we won't need
         * that anymore.
         */
        kfree(devname_garbage);
        return ret;
    }
    data->dir = igrab(dir);
    if (!data->dir) {
        nfs_dec_sillycount(dir);
        return 0;
    }
    nfs_sb_active(dir->i_sb);
    data->args.fh = NFS_FH(dir);
    nfs_fattr_init(data->res.dir_attr);

    NFS_PROTO(dir)->unlink_setup(&msg, dir);

    task_setup_data.rpc_client = NFS_CLIENT(dir);
    task = rpc_run_task(&task_setup_data);
    if (!IS_ERR(task))
        rpc_put_task_async(task);
    return 1;
}

static int nfs_call_unlink(struct dentry *dentry, struct nfs_unlinkdata *data)
{
    struct dentry *parent;
    struct inode *dir;
    int ret = 0;


    parent = dget_parent(dentry);
    if (parent == NULL)
        goto out_free;
    dir = parent->d_inode;
    /* Non-exclusive lock protects against concurrent lookup() calls */
    spin_lock(&dir->i_lock);
    if (atomic_inc_not_zero(&NFS_I(dir)->silly_count) == 0) {
        /* Deferred delete */
        hlist_add_head(&data->list, &NFS_I(dir)->silly_list);
        spin_unlock(&dir->i_lock);
        ret = 1;
        goto out_dput;
    }
    spin_unlock(&dir->i_lock);
    ret = nfs_do_call_unlink(parent, dir, data);
out_dput:
    dput(parent);
out_free:
    return ret;
}

void nfs_block_sillyrename(struct dentry *dentry)
{
    struct nfs_inode *nfsi = NFS_I(dentry->d_inode);

    wait_event(nfsi->waitqueue, atomic_cmpxchg(&nfsi->silly_count, 1, 0) == 1);
}

void nfs_unblock_sillyrename(struct dentry *dentry)
{
    struct inode *dir = dentry->d_inode;
    struct nfs_inode *nfsi = NFS_I(dir);
    struct nfs_unlinkdata *data;

    atomic_inc(&nfsi->silly_count);
    spin_lock(&dir->i_lock);
    while (!hlist_empty(&nfsi->silly_list)) {
        if (!atomic_inc_not_zero(&nfsi->silly_count))
            break;
        data = hlist_entry(nfsi->silly_list.first, struct nfs_unlinkdata, list);
        hlist_del(&data->list);
        spin_unlock(&dir->i_lock);
        if (nfs_do_call_unlink(dentry, dir, data) == 0)
            nfs_free_unlinkdata(data);
        spin_lock(&dir->i_lock);
    }
    spin_unlock(&dir->i_lock);
}

static int
nfs_async_unlink(struct inode *dir, struct dentry *dentry)
{
    struct nfs_unlinkdata *data;
    int status = -ENOMEM;
    void *devname_garbage = NULL;

    data = kzalloc(sizeof(*data), GFP_KERNEL);
    if (data == NULL)
        goto out;

    data->cred = rpc_lookup_cred();
    if (IS_ERR(data->cred)) {
        status = PTR_ERR(data->cred);
        goto out_free;
    }
    data->res.dir_attr = &data->dir_attr;

    status = -EBUSY;
    spin_lock(&dentry->d_lock);
    if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
        goto out_unlock;
    dentry->d_flags |= DCACHE_NFSFS_RENAMED;
    devname_garbage = dentry->d_fsdata;
    dentry->d_fsdata = data;
    spin_unlock(&dentry->d_lock);
    /*
     * If we'd displaced old cached devname, free it.  At that
     * point dentry is definitely not a root, so we won't need
     * that anymore.
     */
    if (devname_garbage)
        kfree(devname_garbage);
    return 0;
out_unlock:
    spin_unlock(&dentry->d_lock);
    put_rpccred(data->cred);
out_free:
    kfree(data);
out:
    return status;
}

void
nfs_complete_unlink(struct dentry *dentry, struct inode *inode)
{
    struct nfs_unlinkdata   *data = NULL;

    spin_lock(&dentry->d_lock);
    if (dentry->d_flags & DCACHE_NFSFS_RENAMED) {
        dentry->d_flags &= ~DCACHE_NFSFS_RENAMED;
        data = dentry->d_fsdata;
        dentry->d_fsdata = NULL;
    }
    spin_unlock(&dentry->d_lock);

    if (data != NULL && (NFS_STALE(inode) || !nfs_call_unlink(dentry, data)))
        nfs_free_unlinkdata(data);
}

/* Cancel a queued async unlink. Called when a sillyrename run fails. */
static void
nfs_cancel_async_unlink(struct dentry *dentry)
{
    spin_lock(&dentry->d_lock);
    if (dentry->d_flags & DCACHE_NFSFS_RENAMED) {
        struct nfs_unlinkdata *data = dentry->d_fsdata;

        dentry->d_flags &= ~DCACHE_NFSFS_RENAMED;
        dentry->d_fsdata = NULL;
        spin_unlock(&dentry->d_lock);
        nfs_free_unlinkdata(data);
        return;
    }
    spin_unlock(&dentry->d_lock);
}

static void nfs_async_rename_done(struct rpc_task *task, void *calldata)
{
    struct nfs_renamedata *data = calldata;
    struct inode *old_dir = data->old_dir;
    struct inode *new_dir = data->new_dir;
    struct dentry *old_dentry = data->old_dentry;
    struct dentry *new_dentry = data->new_dentry;

    if (!NFS_PROTO(old_dir)->rename_done(task, old_dir, new_dir)) {
        rpc_restart_call_prepare(task);
        return;
    }

    if (task->tk_status != 0) {
        nfs_cancel_async_unlink(old_dentry);
        return;
    }

    d_drop(old_dentry);
    d_drop(new_dentry);
}

static void nfs_async_rename_release(void *calldata)
{
    struct nfs_renamedata   *data = calldata;
    struct super_block *sb = data->old_dir->i_sb;

    if (data->old_dentry->d_inode)
        nfs_mark_for_revalidate(data->old_dentry->d_inode);

    dput(data->old_dentry);
    dput(data->new_dentry);
    iput(data->old_dir);
    iput(data->new_dir);
    nfs_sb_deactive(sb);
    put_rpccred(data->cred);
    kfree(data);
}

static void nfs_rename_prepare(struct rpc_task *task, void *calldata)
{
    struct nfs_renamedata *data = calldata;
    NFS_PROTO(data->old_dir)->rename_rpc_prepare(task, data);
}

static const struct rpc_call_ops nfs_rename_ops = {
    .rpc_call_done = nfs_async_rename_done,
    .rpc_release = nfs_async_rename_release,
    .rpc_call_prepare = nfs_rename_prepare,
};

static struct rpc_task *
nfs_async_rename(struct inode *old_dir, struct inode *new_dir,
         struct dentry *old_dentry, struct dentry *new_dentry)
{
    struct nfs_renamedata *data;
    struct rpc_message msg = { };
    struct rpc_task_setup task_setup_data = {
        .rpc_message = &msg,
        .callback_ops = &nfs_rename_ops,
        .workqueue = nfsiod_workqueue,
        .rpc_client = NFS_CLIENT(old_dir),
        .flags = RPC_TASK_ASYNC,
    };

    data = kzalloc(sizeof(*data), GFP_KERNEL);
    if (data == NULL)
        return ERR_PTR(-ENOMEM);
    task_setup_data.callback_data = data;

    data->cred = rpc_lookup_cred();
    if (IS_ERR(data->cred)) {
        struct rpc_task *task = ERR_CAST(data->cred);
        kfree(data);
        return task;
    }

    msg.rpc_argp = &data->args;
    msg.rpc_resp = &data->res;
    msg.rpc_cred = data->cred;

    /* set up nfs_renamedata */
    data->old_dir = old_dir;
    ihold(old_dir);
    data->new_dir = new_dir;
    ihold(new_dir);
    data->old_dentry = dget(old_dentry);
    data->new_dentry = dget(new_dentry);
    nfs_fattr_init(&data->old_fattr);
    nfs_fattr_init(&data->new_fattr);

    /* set up nfs_renameargs */
    data->args.old_dir = NFS_FH(old_dir);
    data->args.old_name = &old_dentry->d_name;
    data->args.new_dir = NFS_FH(new_dir);
    data->args.new_name = &new_dentry->d_name;

    /* set up nfs_renameres */
    data->res.old_fattr = &data->old_fattr;
    data->res.new_fattr = &data->new_fattr;

    nfs_sb_active(old_dir->i_sb);

    NFS_PROTO(data->old_dir)->rename_setup(&msg, old_dir);

    return rpc_run_task(&task_setup_data);
}

int
nfs_sillyrename(struct inode *dir, struct dentry *dentry)
{
    static unsigned int sillycounter;
    const int      fileidsize  = sizeof(NFS_FILEID(dentry->d_inode))*2;
    const int      countersize = sizeof(sillycounter)*2;
    const int      slen        = sizeof(".nfs")+fileidsize+countersize-1;
    char           silly[slen+1];
    struct dentry *sdentry;
    struct rpc_task *task;
    int            error = -EIO;

    dfprintk(VFS, "NFS: silly-rename(%s/%s, ct=%d)\n",
        dentry->d_parent->d_name.name, dentry->d_name.name,
        dentry->d_count);
    nfs_inc_stats(dir, NFSIOS_SILLYRENAME);

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

    sprintf(silly, ".nfs%*.*Lx",
        fileidsize, fileidsize,
        (unsigned long long)NFS_FILEID(dentry->d_inode));

    /* Return delegation in anticipation of the rename */
    NFS_PROTO(dentry->d_inode)->return_delegation(dentry->d_inode);

    sdentry = NULL;
    do {
        char *suffix = silly + slen - countersize;

        dput(sdentry);
        sillycounter++;
        sprintf(suffix, "%*.*x", countersize, countersize, sillycounter);

        dfprintk(VFS, "NFS: trying to rename %s to %s\n",
                dentry->d_name.name, silly);

        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 (sdentry->d_inode != NULL); /* need negative lookup */

    /* queue unlink first. Can't do this from rpc_release as it
     * has to allocate memory
     */
    error = nfs_async_unlink(dir, dentry);
    if (error)
        goto out_dput;

    /* populate unlinkdata with the right dname */
    error = nfs_copy_dname(sdentry,
                (struct nfs_unlinkdata *)dentry->d_fsdata);
    if (error) {
        nfs_cancel_async_unlink(dentry);
        goto out_dput;
    }

    /* run the rename task, undo unlink if it fails */
    task = nfs_async_rename(dir, dir, dentry, sdentry);
    if (IS_ERR(task)) {
        error = -EBUSY;
        nfs_cancel_async_unlink(dentry);
        goto out_dput;
    }

    /* wait for the RPC task to complete, unless a SIGKILL intervenes */
    error = rpc_wait_for_completion_task(task);
    if (error == 0)
        error = task->tk_status;
    rpc_put_task(task);
out_dput:
    dput(sdentry);
out:
    return error;
}