root/fs/nfs/unlink.c

DEFINITIONS

1. nfs_free_unlinkdata
2. nfs_copy_dname
3. nfs_free_dname
4. nfs_dec_sillycount
5. nfs_async_unlink_done
6. nfs_async_unlink_release
7. nfs_do_call_unlink
8. nfs_call_unlink
9. nfs_block_sillyrename
10. nfs_unblock_sillyrename
11. nfs_async_unlink
12. nfs_complete_unlink

/*
 *  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 "internal.h"

struct nfs_unlinkdata {
        struct hlist_node list;
        struct nfs_removeargs args;
        struct nfs_removeres res;
        struct inode *dir;
        struct rpc_cred *cred;
};

/**
 * nfs_free_unlinkdata - release data from a sillydelete operation.
 * @data: pointer to unlink structure.
 */
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)
/**
 * nfs_copy_dname - copy dentry name to data structure
 * @dentry: pointer to dentry
 * @data: nfs_unlinkdata
 */
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);
}

/**
 * nfs_async_unlink_done - Sillydelete post-processing
 * @task: rpc_task of the sillydelete
 *
 * Do the directory attribute update.
 */
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(task);
}

/**
 * nfs_async_unlink_release - Release the sillydelete data.
 * @task: rpc_task of the sillydelete
 *
 * 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)
{
        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(NFS_SB(sb));
}

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

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,
                .flags = RPC_TASK_ASYNC,
        };
        struct rpc_task *task;
        struct dentry *alias;

        alias = d_lookup(parent, &data->args.name);
        if (alias != NULL) {
                int ret = 0;

                /*
                 * Hey, we raced with lookup... See if we need to transfer
                 * the sillyrename information to the aliased dentry.
                 */
                nfs_free_dname(data);
                spin_lock(&alias->d_lock);
                if (alias->d_inode != NULL &&
                    !(alias->d_flags & DCACHE_NFSFS_RENAMED)) {
                        alias->d_fsdata = data;
                        alias->d_flags |= DCACHE_NFSFS_RENAMED;
                        ret = 1;
                }
                spin_unlock(&alias->d_lock);
                nfs_dec_sillycount(dir);
                dput(alias);
                return ret;
        }
        data->dir = igrab(dir);
        if (!data->dir) {
                nfs_dec_sillycount(dir);
                return 0;
        }
        nfs_sb_active(NFS_SERVER(dir));
        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(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;
        if (nfs_copy_dname(dentry, data) != 0)
                goto out_dput;
        /* 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);
}

/**
 * nfs_async_unlink - asynchronous unlinking of a file
 * @dir: parent directory of dentry
 * @dentry: dentry to unlink
 */
int
nfs_async_unlink(struct inode *dir, struct dentry *dentry)
{
        struct nfs_unlinkdata *data;
        int status = -ENOMEM;

        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;
        }

        status = -EBUSY;
        spin_lock(&dentry->d_lock);
        if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
                goto out_unlock;
        dentry->d_flags |= DCACHE_NFSFS_RENAMED;
        dentry->d_fsdata = data;
        spin_unlock(&dentry->d_lock);
        return 0;
out_unlock:
        spin_unlock(&dentry->d_lock);
        put_rpccred(data->cred);
out_free:
        kfree(data);
out:
        return status;
}

/**
 * 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)
{
        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;
        }
        spin_unlock(&dentry->d_lock);

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