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