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
  91 nfs_async_unlink_init(struct rpc_task *task)
  92 {
  93         struct nfs_unlinkdata   *data = (struct nfs_unlinkdata *)task->tk_calldata;
  94         struct dentry           *dir = data->dir;
  95         struct rpc_message      msg = {
  96                 .rpc_cred       = data->cred,
  97         };
  98         int                     status = -ENOENT;
  99
 100         if (!data->name.len)
 101                 goto out_err;
 102
 103         status = NFS_PROTO(dir->d_inode)->unlink_setup(&msg, dir, &data->name);
 104         if (status < 0)
 105                 goto out_err;
 106         nfs_begin_data_update(dir->d_inode);
 107         rpc_call_setup(task, &msg, 0);
 108         return;
 109  out_err:
 110         rpc_exit(task, status);
 111 }
 112
 113 /**
 114  * nfs_async_unlink_done - Sillydelete post-processing
 115  * @task: rpc_task of the sillydelete
 116  *
 117  * Do the directory attribute update.
 118  */
 119 static void
 120 nfs_async_unlink_done(struct rpc_task *task)
 121 {
 122         struct nfs_unlinkdata   *data = (struct nfs_unlinkdata *)task->tk_calldata;
 123         struct dentry           *dir = data->dir;
 124         struct inode            *dir_i;
 125
 126         if (!dir)
 127                 return;
 128         dir_i = dir->d_inode;
 129         nfs_end_data_update(dir_i);
 130         if (NFS_PROTO(dir_i)->unlink_done(dir, task))
 131                 return;
 132         put_rpccred(data->cred);
 133         data->cred = NULL;
 134         dput(dir);
 135 }
 136
 137 /**
 138  * nfs_async_unlink_release - Release the sillydelete data.
 139  * @task: rpc_task of the sillydelete
 140  *
 141  * We need to call nfs_put_unlinkdata as a 'tk_release' task since the
 142  * rpc_task would be freed too.
 143  */
 144 static void
 145 nfs_async_unlink_release(struct rpc_task *task)
 146 {
 147         struct nfs_unlinkdata   *data = (struct nfs_unlinkdata *)task->tk_calldata;
 148         nfs_put_unlinkdata(data);
 149 }
 150
 151 /**
 152  * nfs_async_unlink - asynchronous unlinking of a file
 153  * @dentry: dentry to unlink
 154  */
 155 int
 156 nfs_async_unlink(struct dentry *dentry)
 157 {
 158         struct dentry   *dir = dentry->d_parent;
 159         struct nfs_unlinkdata   *data;
 160         struct rpc_task *task;
 161         struct rpc_clnt *clnt = NFS_CLIENT(dir->d_inode);
 162         int             status = -ENOMEM;
 163
 164         data = kmalloc(sizeof(*data), GFP_KERNEL);
 165         if (!data)
 166                 goto out;
 167         memset(data, 0, sizeof(*data));
 168
 169         data->cred = rpcauth_lookupcred(clnt->cl_auth, 0);
 170         if (IS_ERR(data->cred)) {
 171                 status = PTR_ERR(data->cred);
 172                 goto out_free;
 173         }
 174         data->dir = dget(dir);
 175         data->dentry = dentry;
 176
 177         data->next = nfs_deletes;
 178         nfs_deletes = data;
 179         data->count = 1;
 180
 181         task = &data->task;
 182         rpc_init_task(task, clnt, nfs_async_unlink_done , RPC_TASK_ASYNC);
 183         task->tk_calldata = data;
 184         task->tk_action = nfs_async_unlink_init;
 185         task->tk_release = nfs_async_unlink_release;
 186
 187         spin_lock(&dentry->d_lock);
 188         dentry->d_flags |= DCACHE_NFSFS_RENAMED;
 189         spin_unlock(&dentry->d_lock);
 190
 191         rpc_sleep_on(&nfs_delete_queue, task, NULL, NULL);
 192         status = 0;
 193  out:
 194         return status;
 195 out_free:
 196         kfree(data);
 197         return status;
 198 }
 199
 200 /**
 201  * nfs_complete_unlink - Initialize completion of the sillydelete
 202  * @dentry: dentry to delete
 203  *
 204  * Since we're most likely to be called by dentry_iput(), we
 205  * only use the dentry to find the sillydelete. We then copy the name
 206  * into the qstr.
 207  */
 208 void
 209 nfs_complete_unlink(struct dentry *dentry)
 210 {
 211         struct nfs_unlinkdata   *data;
 212
 213         for(data = nfs_deletes; data != NULL; data = data->next) {
 214                 if (dentry == data->dentry)
 215                         break;
 216         }
 217         if (!data)
 218                 return;
 219         data->count++;
 220         nfs_copy_dname(dentry, data);
 221         spin_lock(&dentry->d_lock);
 222         dentry->d_flags &= ~DCACHE_NFSFS_RENAMED;
 223         spin_unlock(&dentry->d_lock);
 224         rpc_wake_up_task(&data->task);
 225         nfs_put_unlinkdata(data);
 226 }