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                 if (data->name.name != NULL)
  56                         kfree(data->name.name);
  57                 kfree(data);
  58         }
  59 }
  60
  61 #define NAME_ALLOC_LEN(len)     ((len+16) & ~15)
  62 /**
  63  * nfs_copy_dname - copy dentry name to data structure
  64  * @dentry: pointer to dentry
  65  * @data: nfs_unlinkdata
  66  */
  67 static inline void
  68 nfs_copy_dname(struct dentry *dentry, struct nfs_unlinkdata *data)
  69 {
  70         char            *str;
  71         int             len = dentry->d_name.len;
  72
  73         str = kmalloc(NAME_ALLOC_LEN(len), GFP_KERNEL);
  74         if (!str)
  75                 return;
  76         memcpy(str, dentry->d_name.name, len);
  77         if (!data->name.len) {
  78                 data->name.len = len;
  79                 data->name.name = str;
  80         } else
  81                 kfree(str);
  82 }
  83
  84 /**
  85  * nfs_async_unlink_init - Initialize the RPC info
  86  * @task: rpc_task of the sillydelete
  87  *
  88  * We delay initializing RPC info until after the call to dentry_iput()
  89  * in order to minimize races against rename().
  90  */
  91 static void
  92 nfs_async_unlink_init(struct rpc_task *task)
  93 {
  94         struct nfs_unlinkdata   *data = (struct nfs_unlinkdata *)task->tk_calldata;
  95         struct dentry           *dir = data->dir;
  96         struct rpc_message      msg = {
  97                 .rpc_cred       = data->cred,
  98         };
  99         int                     status = -ENOENT;
 100
 101         if (!data->name.len)
 102                 goto out_err;
 103
 104         status = NFS_PROTO(dir->d_inode)->unlink_setup(&msg, dir, &data->name);
 105         if (status < 0)
 106                 goto out_err;
 107         nfs_begin_data_update(dir->d_inode);
 108         rpc_call_setup(task, &msg, 0);
 109         return;
 110  out_err:
 111         rpc_exit(task, status);
 112 }
 113
 114 /**
 115  * nfs_async_unlink_done - Sillydelete post-processing
 116  * @task: rpc_task of the sillydelete
 117  *
 118  * Do the directory attribute update.
 119  */
 120 static void
 121 nfs_async_unlink_done(struct rpc_task *task)
 122 {
 123         struct nfs_unlinkdata   *data = (struct nfs_unlinkdata *)task->tk_calldata;
 124         struct dentry           *dir = data->dir;
 125         struct inode            *dir_i;
 126
 127         if (!dir)
 128                 return;
 129         dir_i = dir->d_inode;
 130         nfs_end_data_update(dir_i);
 131         if (NFS_PROTO(dir_i)->unlink_done(dir, task))
 132                 return;
 133         put_rpccred(data->cred);
 134         data->cred = NULL;
 135         dput(dir);
 136 }
 137
 138 /**
 139  * nfs_async_unlink_release - Release the sillydelete data.
 140  * @task: rpc_task of the sillydelete
 141  *
 142  * We need to call nfs_put_unlinkdata as a 'tk_release' task since the
 143  * rpc_task would be freed too.
 144  */
 145 static void
 146 nfs_async_unlink_release(struct rpc_task *task)
 147 {
 148         struct nfs_unlinkdata   *data = (struct nfs_unlinkdata *)task->tk_calldata;
 149         nfs_put_unlinkdata(data);
 150 }
 151
 152 /**
 153  * nfs_async_unlink - asynchronous unlinking of a file
 154  * @dentry: dentry to unlink
 155  */
 156 int
 157 nfs_async_unlink(struct dentry *dentry)
 158 {
 159         struct dentry   *dir = dentry->d_parent;
 160         struct nfs_unlinkdata   *data;
 161         struct rpc_task *task;
 162         struct rpc_clnt *clnt = NFS_CLIENT(dir->d_inode);
 163         int             status = -ENOMEM;
 164
 165         data = kmalloc(sizeof(*data), GFP_KERNEL);
 166         if (!data)
 167                 goto out;
 168         memset(data, 0, sizeof(*data));
 169
 170         data->cred = rpcauth_lookupcred(clnt->cl_auth, 0);
 171         if (IS_ERR(data->cred)) {
 172                 status = PTR_ERR(data->cred);
 173                 goto out_free;
 174         }
 175         data->dir = dget(dir);
 176         data->dentry = dentry;
 177
 178         data->next = nfs_deletes;
 179         nfs_deletes = data;
 180         data->count = 1;
 181
 182         task = &data->task;
 183         rpc_init_task(task, clnt, nfs_async_unlink_done , RPC_TASK_ASYNC);
 184         task->tk_calldata = data;
 185         task->tk_action = nfs_async_unlink_init;
 186         task->tk_release = nfs_async_unlink_release;
 187
 188         spin_lock(&dentry->d_lock);
 189         dentry->d_flags |= DCACHE_NFSFS_RENAMED;
 190         spin_unlock(&dentry->d_lock);
 191
 192         rpc_sleep_on(&nfs_delete_queue, task, NULL, NULL);
 193         status = 0;
 194  out:
 195         return status;
 196 out_free:
 197         kfree(data);
 198         return status;
 199 }
 200
 201 /**
 202  * nfs_complete_unlink - Initialize completion of the sillydelete
 203  * @dentry: dentry to delete
 204  *
 205  * Since we're most likely to be called by dentry_iput(), we
 206  * only use the dentry to find the sillydelete. We then copy the name
 207  * into the qstr.
 208  */
 209 void
 210 nfs_complete_unlink(struct dentry *dentry)
 211 {
 212         struct nfs_unlinkdata   *data;
 213
 214         for(data = nfs_deletes; data != NULL; data = data->next) {
 215                 if (dentry == data->dentry)
 216                         break;
 217         }
 218         if (!data)
 219                 return;
 220         data->count++;
 221         nfs_copy_dname(dentry, data);
 222         spin_lock(&dentry->d_lock);
 223         dentry->d_flags &= ~DCACHE_NFSFS_RENAMED;
 224         spin_unlock(&dentry->d_lock);
 225         rpc_wake_up_task(&data->task);
 226         nfs_put_unlinkdata(data);
 227 }