fs/nfs/unlink.c

   1 /*
   2  *  linux/fs/nfs/unlink.c
   3  *
   4  * nfs sillydelete handling
   5  *
   6  * NOTE: we rely on holding the BKL for list manipulation protection.
   7  */
   8
   9 #include <linux/slab.h>
  10 #include <linux/string.h>
  11 #include <linux/dcache.h>
  12 #include <linux/sunrpc/sched.h>
  13 #include <linux/sunrpc/clnt.h>
  14 #include <linux/nfs_fs.h>
  15
  16
  17 struct nfs_unlinkdata {
  18         struct nfs_unlinkdata   *next;
  19         struct dentry   *dir, *dentry;
  20         struct qstr     name;
  21         struct rpc_task task;
  22         struct rpc_cred *cred;
  23         unsigned int    count;
  24 };
  25
  26 static struct nfs_unlinkdata    *nfs_deletes;
  27 static RPC_WAITQ(nfs_delete_queue, "nfs_delete_queue");
  28
  29 /**
  30  * nfs_detach_unlinkdata - Remove asynchronous unlink from global list
  31  * @data: pointer to descriptor
  32  */
  33 static inline void
  34 nfs_detach_unlinkdata(struct nfs_unlinkdata *data)
  35 {
  36         struct nfs_unlinkdata   **q;
  37
  38         for (q = &nfs_deletes; *q != NULL; q = &((*q)->next)) {
  39                 if (*q == data) {
  40                         *q = data->next;
  41                         break;
  42                 }
  43         }
  44 }
  45
  46 /**
  47  * nfs_put_unlinkdata - release data from a sillydelete operation.
  48  * @data: pointer to unlink structure.
  49  */
  50 static void
  51 nfs_put_unlinkdata(struct nfs_unlinkdata *data)
  52 {
  53         if (--data->count == 0) {
  54                 nfs_detach_unlinkdata(data);
  55                 kfree(data->name.name);
  56                 kfree(data);
  57         }
  58 }
  59
  60 #define NAME_ALLOC_LEN(len)     ((len+16) & ~15)
  61 /**
  62  * nfs_copy_dname - copy dentry name to data structure
  63  * @dentry: pointer to dentry
  64  * @data: nfs_unlinkdata
  65  */
  66 static inline void
  67 nfs_copy_dname(struct dentry *dentry, struct nfs_unlinkdata *data)
  68 {
  69         char            *str;
  70         int             len = dentry->d_name.len;
  71
  72         str = kmalloc(NAME_ALLOC_LEN(len), GFP_KERNEL);
  73         if (!str)
  74                 return;
  75         memcpy(str, dentry->d_name.name, len);
  76         if (!data->name.len) {
  77                 data->name.len = len;
  78                 data->name.name = str;
  79         } else
  80                 kfree(str);
  81 }
  82
  83 /**
  84  * nfs_async_unlink_init - Initialize the RPC info
  85  * @task: rpc_task of the sillydelete
  86  *
  87  * We delay initializing RPC info until after the call to dentry_iput()
  88  * in order to minimize races against rename().
  89  */
  90 static void nfs_async_unlink_init(struct rpc_task *task, void *calldata)
  91 {
  92         struct nfs_unlinkdata   *data = calldata;
  93         struct dentry           *dir = data->dir;
  94         struct rpc_message      msg = {
  95                 .rpc_cred       = data->cred,
  96         };
  97         int                     status = -ENOENT;
  98
  99         if (!data->name.len)
 100                 goto out_err;
 101
 102         status = NFS_PROTO(dir->d_inode)->unlink_setup(&msg, dir, &data->name);
 103         if (status < 0)
 104                 goto out_err;
 105         nfs_begin_data_update(dir->d_inode);
 106         rpc_call_setup(task, &msg, 0);
 107         return;
 108  out_err:
 109         rpc_exit(task, status);
 110 }
 111
 112 /**
 113  * nfs_async_unlink_done - Sillydelete post-processing
 114  * @task: rpc_task of the sillydelete
 115  *
 116  * Do the directory attribute update.
 117  */
 118 static void nfs_async_unlink_done(struct rpc_task *task, void *calldata)
 119 {
 120         struct nfs_unlinkdata   *data = calldata;
 121         struct dentry           *dir = data->dir;
 122         struct inode            *dir_i;
 123
 124         if (!dir)
 125                 return;
 126         dir_i = dir->d_inode;
 127         nfs_end_data_update(dir_i);
 128         if (NFS_PROTO(dir_i)->unlink_done(dir, task))
 129                 return;
 130         put_rpccred(data->cred);
 131         data->cred = NULL;
 132         dput(dir);
 133 }
 134
 135 /**
 136  * nfs_async_unlink_release - Release the sillydelete data.
 137  * @task: rpc_task of the sillydelete
 138  *
 139  * We need to call nfs_put_unlinkdata as a 'tk_release' task since the
 140  * rpc_task would be freed too.
 141  */
 142 static void nfs_async_unlink_release(void *calldata)
 143 {
 144         struct nfs_unlinkdata   *data = calldata;
 145         nfs_put_unlinkdata(data);
 146 }
 147
 148 static const struct rpc_call_ops nfs_unlink_ops = {
 149         .rpc_call_prepare = nfs_async_unlink_init,
 150         .rpc_call_done = nfs_async_unlink_done,
 151         .rpc_release = nfs_async_unlink_release,
 152 };
 153
 154 /**
 155  * nfs_async_unlink - asynchronous unlinking of a file
 156  * @dentry: dentry to unlink
 157  */
 158 int
 159 nfs_async_unlink(struct dentry *dentry)
 160 {
 161         struct dentry   *dir = dentry->d_parent;
 162         struct nfs_unlinkdata   *data;
 163         struct rpc_clnt *clnt = NFS_CLIENT(dir->d_inode);
 164         int             status = -ENOMEM;
 165
 166         data = kmalloc(sizeof(*data), GFP_KERNEL);
 167         if (!data)
 168                 goto out;
 169         memset(data, 0, sizeof(*data));
 170
 171         data->cred = rpcauth_lookupcred(clnt->cl_auth, 0);
 172         if (IS_ERR(data->cred)) {
 173                 status = PTR_ERR(data->cred);
 174                 goto out_free;
 175         }
 176         data->dir = dget(dir);
 177         data->dentry = dentry;
 178
 179         data->next = nfs_deletes;
 180         nfs_deletes = data;
 181         data->count = 1;
 182
 183         rpc_init_task(&data->task, clnt, RPC_TASK_ASYNC, &nfs_unlink_ops, data);
 184
 185         spin_lock(&dentry->d_lock);
 186         dentry->d_flags |= DCACHE_NFSFS_RENAMED;
 187         spin_unlock(&dentry->d_lock);
 188
 189         rpc_sleep_on(&nfs_delete_queue, &data->task, NULL, NULL);
 190         status = 0;
 191  out:
 192         return status;
 193 out_free:
 194         kfree(data);
 195         return status;
 196 }
 197
 198 /**
 199  * nfs_complete_unlink - Initialize completion of the sillydelete
 200  * @dentry: dentry to delete
 201  *
 202  * Since we're most likely to be called by dentry_iput(), we
 203  * only use the dentry to find the sillydelete. We then copy the name
 204  * into the qstr.
 205  */
 206 void
 207 nfs_complete_unlink(struct dentry *dentry)
 208 {
 209         struct nfs_unlinkdata   *data;
 210
 211         for(data = nfs_deletes; data != NULL; data = data->next) {
 212                 if (dentry == data->dentry)
 213                         break;
 214         }
 215         if (!data)
 216                 return;
 217         data->count++;
 218         nfs_copy_dname(dentry, data);
 219         spin_lock(&dentry->d_lock);
 220         dentry->d_flags &= ~DCACHE_NFSFS_RENAMED;
 221         spin_unlock(&dentry->d_lock);
 222         rpc_wake_up_task(&data->task);
 223         nfs_put_unlinkdata(data);
 224 }