fs/nfs/unlink.c

   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(NFS_SB(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                 .flags = RPC_TASK_ASYNC,
 122         };
 123         struct rpc_task *task;
 124         struct dentry *alias;
 125
 126         alias = d_lookup(parent, &data->args.name);
 127         if (alias != NULL) {
 128                 int ret = 0;
 129
 130                 /*
 131                  * Hey, we raced with lookup... See if we need to transfer
 132                  * the sillyrename information to the aliased dentry.
 133                  */
 134                 nfs_free_dname(data);
 135                 spin_lock(&alias->d_lock);
 136                 if (alias->d_inode != NULL &&
 137                     !(alias->d_flags & DCACHE_NFSFS_RENAMED)) {
 138                         alias->d_fsdata = data;
 139                         alias->d_flags |= DCACHE_NFSFS_RENAMED;
 140                         ret = 1;
 141                 }
 142                 spin_unlock(&alias->d_lock);
 143                 nfs_dec_sillycount(dir);
 144                 dput(alias);
 145                 return ret;
 146         }
 147         data->dir = igrab(dir);
 148         if (!data->dir) {
 149                 nfs_dec_sillycount(dir);
 150                 return 0;
 151         }
 152         nfs_sb_active(NFS_SERVER(dir));
 153         data->args.fh = NFS_FH(dir);
 154         nfs_fattr_init(&data->res.dir_attr);
 155
 156         NFS_PROTO(dir)->unlink_setup(&msg, dir);
 157
 158         task_setup_data.rpc_client = NFS_CLIENT(dir);
 159         task = rpc_run_task(&task_setup_data);
 160         if (!IS_ERR(task))
 161                 rpc_put_task(task);
 162         return 1;
 163 }
 164
 165 static int nfs_call_unlink(struct dentry *dentry, struct nfs_unlinkdata *data)
 166 {
 167         struct dentry *parent;
 168         struct inode *dir;
 169         int ret = 0;
 170
 171
 172         parent = dget_parent(dentry);
 173         if (parent == NULL)
 174                 goto out_free;
 175         dir = parent->d_inode;
 176         if (nfs_copy_dname(dentry, data) != 0)
 177                 goto out_dput;
 178         /* Non-exclusive lock protects against concurrent lookup() calls */
 179         spin_lock(&dir->i_lock);
 180         if (atomic_inc_not_zero(&NFS_I(dir)->silly_count) == 0) {
 181                 /* Deferred delete */
 182                 hlist_add_head(&data->list, &NFS_I(dir)->silly_list);
 183                 spin_unlock(&dir->i_lock);
 184                 ret = 1;
 185                 goto out_dput;
 186         }
 187         spin_unlock(&dir->i_lock);
 188         ret = nfs_do_call_unlink(parent, dir, data);
 189 out_dput:
 190         dput(parent);
 191 out_free:
 192         return ret;
 193 }
 194
 195 void nfs_block_sillyrename(struct dentry *dentry)
 196 {
 197         struct nfs_inode *nfsi = NFS_I(dentry->d_inode);
 198
 199         wait_event(nfsi->waitqueue, atomic_cmpxchg(&nfsi->silly_count, 1, 0) == 1);
 200 }
 201
 202 void nfs_unblock_sillyrename(struct dentry *dentry)
 203 {
 204         struct inode *dir = dentry->d_inode;
 205         struct nfs_inode *nfsi = NFS_I(dir);
 206         struct nfs_unlinkdata *data;
 207
 208         atomic_inc(&nfsi->silly_count);
 209         spin_lock(&dir->i_lock);
 210         while (!hlist_empty(&nfsi->silly_list)) {
 211                 if (!atomic_inc_not_zero(&nfsi->silly_count))
 212                         break;
 213                 data = hlist_entry(nfsi->silly_list.first, struct nfs_unlinkdata, list);
 214                 hlist_del(&data->list);
 215                 spin_unlock(&dir->i_lock);
 216                 if (nfs_do_call_unlink(dentry, dir, data) == 0)
 217                         nfs_free_unlinkdata(data);
 218                 spin_lock(&dir->i_lock);
 219         }
 220         spin_unlock(&dir->i_lock);
 221 }
 222
 223 /**
 224  * nfs_async_unlink - asynchronous unlinking of a file
 225  * @dir: parent directory of dentry
 226  * @dentry: dentry to unlink
 227  */
 228 int
 229 nfs_async_unlink(struct inode *dir, struct dentry *dentry)
 230 {
 231         struct nfs_unlinkdata *data;
 232         int status = -ENOMEM;
 233
 234         data = kzalloc(sizeof(*data), GFP_KERNEL);
 235         if (data == NULL)
 236                 goto out;
 237
 238         data->cred = rpc_lookup_cred();
 239         if (IS_ERR(data->cred)) {
 240                 status = PTR_ERR(data->cred);
 241                 goto out_free;
 242         }
 243
 244         status = -EBUSY;
 245         spin_lock(&dentry->d_lock);
 246         if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
 247                 goto out_unlock;
 248         dentry->d_flags |= DCACHE_NFSFS_RENAMED;
 249         dentry->d_fsdata = data;
 250         spin_unlock(&dentry->d_lock);
 251         return 0;
 252 out_unlock:
 253         spin_unlock(&dentry->d_lock);
 254         put_rpccred(data->cred);
 255 out_free:
 256         kfree(data);
 257 out:
 258         return status;
 259 }
 260
 261 /**
 262  * nfs_complete_unlink - Initialize completion of the sillydelete
 263  * @dentry: dentry to delete
 264  * @inode: inode
 265  *
 266  * Since we're most likely to be called by dentry_iput(), we
 267  * only use the dentry to find the sillydelete. We then copy the name
 268  * into the qstr.
 269  */
 270 void
 271 nfs_complete_unlink(struct dentry *dentry, struct inode *inode)
 272 {
 273         struct nfs_unlinkdata   *data = NULL;
 274
 275         spin_lock(&dentry->d_lock);
 276         if (dentry->d_flags & DCACHE_NFSFS_RENAMED) {
 277                 dentry->d_flags &= ~DCACHE_NFSFS_RENAMED;
 278                 data = dentry->d_fsdata;
 279         }
 280         spin_unlock(&dentry->d_lock);
 281
 282         if (data != NULL && (NFS_STALE(inode) || !nfs_call_unlink(dentry, data)))
 283                 nfs_free_unlinkdata(data);
 284 }