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   1 /*
   2  *  linux/fs/nfs/unlink.c
   3  *
   4  * nfs sillydelete handling
   5  *
   6  */
   7
   8 #include <linux/slab.h>
   9 #include <linux/string.h>
  10 #include <linux/dcache.h>
  11 #include <linux/sunrpc/sched.h>
  12 #include <linux/sunrpc/clnt.h>
  13 #include <linux/nfs_fs.h>
  14 #include <linux/sched.h>
  15 #include <linux/wait.h>
  16
  17 #include "internal.h"
  18
  19 struct nfs_unlinkdata {
  20         struct hlist_node list;
  21         struct nfs_removeargs args;
  22         struct nfs_removeres res;
  23         struct inode *dir;
  24         struct rpc_cred *cred;
  25 };
  26
  27 /**
  28  * nfs_free_unlinkdata - release data from a sillydelete operation.
  29  * @data: pointer to unlink structure.
  30  */
  31 static void
  32 nfs_free_unlinkdata(struct nfs_unlinkdata *data)
  33 {
  34         iput(data->dir);
  35         put_rpccred(data->cred);
  36         kfree(data->args.name.name);
  37         kfree(data);
  38 }
  39
  40 #define NAME_ALLOC_LEN(len)     ((len+16) & ~15)
  41 /**
  42  * nfs_copy_dname - copy dentry name to data structure
  43  * @dentry: pointer to dentry
  44  * @data: nfs_unlinkdata
  45  */
  46 static int nfs_copy_dname(struct dentry *dentry, struct nfs_unlinkdata *data)
  47 {
  48         char            *str;
  49         int             len = dentry->d_name.len;
  50
  51         str = kmemdup(dentry->d_name.name, NAME_ALLOC_LEN(len), GFP_KERNEL);
  52         if (!str)
  53                 return -ENOMEM;
  54         data->args.name.len = len;
  55         data->args.name.name = str;
  56         return 0;
  57 }
  58
  59 static void nfs_free_dname(struct nfs_unlinkdata *data)
  60 {
  61         kfree(data->args.name.name);
  62         data->args.name.name = NULL;
  63         data->args.name.len = 0;
  64 }
  65
  66 static void nfs_dec_sillycount(struct inode *dir)
  67 {
  68         struct nfs_inode *nfsi = NFS_I(dir);
  69         if (atomic_dec_return(&nfsi->silly_count) == 1)
  70                 wake_up(&nfsi->waitqueue);
  71 }
  72
  73 /**
  74  * nfs_async_unlink_done - Sillydelete post-processing
  75  * @task: rpc_task of the sillydelete
  76  *
  77  * Do the directory attribute update.
  78  */
  79 static void nfs_async_unlink_done(struct rpc_task *task, void *calldata)
  80 {
  81         struct nfs_unlinkdata *data = calldata;
  82         struct inode *dir = data->dir;
  83
  84         if (!NFS_PROTO(dir)->unlink_done(task, dir))
  85                 rpc_restart_call(task);
  86 }
  87
  88 /**
  89  * nfs_async_unlink_release - Release the sillydelete data.
  90  * @task: rpc_task of the sillydelete
  91  *
  92  * We need to call nfs_put_unlinkdata as a 'tk_release' task since the
  93  * rpc_task would be freed too.
  94  */
  95 static void nfs_async_unlink_release(void *calldata)
  96 {
  97         struct nfs_unlinkdata   *data = calldata;
  98         struct super_block *sb = data->dir->i_sb;
  99
 100         nfs_dec_sillycount(data->dir);
 101         nfs_free_unlinkdata(data);
 102         nfs_sb_deactive(sb);
 103 }
 104
 105 static const struct rpc_call_ops nfs_unlink_ops = {
 106         .rpc_call_done = nfs_async_unlink_done,
 107         .rpc_release = nfs_async_unlink_release,
 108 };
 109
 110 static int nfs_do_call_unlink(struct dentry *parent, struct inode *dir, struct nfs_unlinkdata *data)
 111 {
 112         struct rpc_message msg = {
 113                 .rpc_argp = &data->args,
 114                 .rpc_resp = &data->res,
 115                 .rpc_cred = data->cred,
 116         };
 117         struct rpc_task_setup task_setup_data = {
 118                 .rpc_message = &msg,
 119                 .callback_ops = &nfs_unlink_ops,
 120                 .callback_data = data,
 121                 .workqueue = nfsiod_workqueue,
 122                 .flags = RPC_TASK_ASYNC,
 123         };
 124         struct rpc_task *task;
 125         struct dentry *alias;
 126
 127         alias = d_lookup(parent, &data->args.name);
 128         if (alias != NULL) {
 129                 int ret = 0;
 130
 131                 /*
 132                  * Hey, we raced with lookup... See if we need to transfer
 133                  * the sillyrename information to the aliased dentry.
 134                  */
 135                 nfs_free_dname(data);
 136                 spin_lock(&alias->d_lock);
 137                 if (alias->d_inode != NULL &&
 138                     !(alias->d_flags & DCACHE_NFSFS_RENAMED)) {
 139                         alias->d_fsdata = data;
 140                         alias->d_flags |= DCACHE_NFSFS_RENAMED;
 141                         ret = 1;
 142                 }
 143                 spin_unlock(&alias->d_lock);
 144                 nfs_dec_sillycount(dir);
 145                 dput(alias);
 146                 return ret;
 147         }
 148         data->dir = igrab(dir);
 149         if (!data->dir) {
 150                 nfs_dec_sillycount(dir);
 151                 return 0;
 152         }
 153         nfs_sb_active(dir->i_sb);
 154         data->args.fh = NFS_FH(dir);
 155         nfs_fattr_init(&data->res.dir_attr);
 156
 157         NFS_PROTO(dir)->unlink_setup(&msg, dir);
 158
 159         task_setup_data.rpc_client = NFS_CLIENT(dir);
 160         task = rpc_run_task(&task_setup_data);
 161         if (!IS_ERR(task))
 162                 rpc_put_task(task);
 163         return 1;
 164 }
 165
 166 static int nfs_call_unlink(struct dentry *dentry, struct nfs_unlinkdata *data)
 167 {
 168         struct dentry *parent;
 169         struct inode *dir;
 170         int ret = 0;
 171
 172
 173         parent = dget_parent(dentry);
 174         if (parent == NULL)
 175                 goto out_free;
 176         dir = parent->d_inode;
 177         if (nfs_copy_dname(dentry, data) != 0)
 178                 goto out_dput;
 179         /* Non-exclusive lock protects against concurrent lookup() calls */
 180         spin_lock(&dir->i_lock);
 181         if (atomic_inc_not_zero(&NFS_I(dir)->silly_count) == 0) {
 182                 /* Deferred delete */
 183                 hlist_add_head(&data->list, &NFS_I(dir)->silly_list);
 184                 spin_unlock(&dir->i_lock);
 185                 ret = 1;
 186                 goto out_dput;
 187         }
 188         spin_unlock(&dir->i_lock);
 189         ret = nfs_do_call_unlink(parent, dir, data);
 190 out_dput:
 191         dput(parent);
 192 out_free:
 193         return ret;
 194 }
 195
 196 void nfs_block_sillyrename(struct dentry *dentry)
 197 {
 198         struct nfs_inode *nfsi = NFS_I(dentry->d_inode);
 199
 200         wait_event(nfsi->waitqueue, atomic_cmpxchg(&nfsi->silly_count, 1, 0) == 1);
 201 }
 202
 203 void nfs_unblock_sillyrename(struct dentry *dentry)
 204 {
 205         struct inode *dir = dentry->d_inode;
 206         struct nfs_inode *nfsi = NFS_I(dir);
 207         struct nfs_unlinkdata *data;
 208
 209         atomic_inc(&nfsi->silly_count);
 210         spin_lock(&dir->i_lock);
 211         while (!hlist_empty(&nfsi->silly_list)) {
 212                 if (!atomic_inc_not_zero(&nfsi->silly_count))
 213                         break;
 214                 data = hlist_entry(nfsi->silly_list.first, struct nfs_unlinkdata, list);
 215                 hlist_del(&data->list);
 216                 spin_unlock(&dir->i_lock);
 217                 if (nfs_do_call_unlink(dentry, dir, data) == 0)
 218                         nfs_free_unlinkdata(data);
 219                 spin_lock(&dir->i_lock);
 220         }
 221         spin_unlock(&dir->i_lock);
 222 }
 223
 224 /**
 225  * nfs_async_unlink - asynchronous unlinking of a file
 226  * @dir: parent directory of dentry
 227  * @dentry: dentry to unlink
 228  */
 229 int
 230 nfs_async_unlink(struct inode *dir, struct dentry *dentry)
 231 {
 232         struct nfs_unlinkdata *data;
 233         int status = -ENOMEM;
 234
 235         data = kzalloc(sizeof(*data), GFP_KERNEL);
 236         if (data == NULL)
 237                 goto out;
 238
 239         data->cred = rpc_lookup_cred();
 240         if (IS_ERR(data->cred)) {
 241                 status = PTR_ERR(data->cred);
 242                 goto out_free;
 243         }
 244
 245         status = -EBUSY;
 246         spin_lock(&dentry->d_lock);
 247         if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
 248                 goto out_unlock;
 249         dentry->d_flags |= DCACHE_NFSFS_RENAMED;
 250         dentry->d_fsdata = data;
 251         spin_unlock(&dentry->d_lock);
 252         return 0;
 253 out_unlock:
 254         spin_unlock(&dentry->d_lock);
 255         put_rpccred(data->cred);
 256 out_free:
 257         kfree(data);
 258 out:
 259         return status;
 260 }
 261
 262 /**
 263  * nfs_complete_unlink - Initialize completion of the sillydelete
 264  * @dentry: dentry to delete
 265  * @inode: inode
 266  *
 267  * Since we're most likely to be called by dentry_iput(), we
 268  * only use the dentry to find the sillydelete. We then copy the name
 269  * into the qstr.
 270  */
 271 void
 272 nfs_complete_unlink(struct dentry *dentry, struct inode *inode)
 273 {
 274         struct nfs_unlinkdata   *data = NULL;
 275
 276         spin_lock(&dentry->d_lock);
 277         if (dentry->d_flags & DCACHE_NFSFS_RENAMED) {
 278                 dentry->d_flags &= ~DCACHE_NFSFS_RENAMED;
 279                 data = dentry->d_fsdata;
 280         }
 281         spin_unlock(&dentry->d_lock);
 282
 283         if (data != NULL && (NFS_STALE(inode) || !nfs_call_unlink(dentry, data)))
 284                 nfs_free_unlinkdata(data);
 285 }