fs/9p/xattr.c

   1 /*
   2  * Copyright IBM Corporation, 2010
   3  * Author Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
   4  *
   5  * This program is free software; you can redistribute it and/or modify it
   6  * under the terms of version 2.1 of the GNU Lesser General Public License
   7  * as published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it would be useful, but
  10  * WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  12  *
  13  */
  14
  15 #include <linux/module.h>
  16 #include <linux/fs.h>
  17 #include <linux/sched.h>
  18 #include <net/9p/9p.h>
  19 #include <net/9p/client.h>
  20
  21 #include "fid.h"
  22 #include "xattr.h"
  23
  24 ssize_t v9fs_fid_xattr_get(struct p9_fid *fid, const char *name,
  25                            void *buffer, size_t buffer_size)
  26 {
  27         ssize_t retval;
  28         int msize, read_count;
  29         u64 offset = 0, attr_size;
  30         struct p9_fid *attr_fid;
  31
  32         attr_fid = p9_client_xattrwalk(fid, name, &attr_size);
  33         if (IS_ERR(attr_fid)) {
  34                 retval = PTR_ERR(attr_fid);
  35                 p9_debug(P9_DEBUG_VFS, "p9_client_attrwalk failed %zd\n",
  36                          retval);
  37                 attr_fid = NULL;
  38                 goto error;
  39         }
  40         if (!buffer_size) {
  41                 /* request to get the attr_size */
  42                 retval = attr_size;
  43                 goto error;
  44         }
  45         if (attr_size > buffer_size) {
  46                 retval = -ERANGE;
  47                 goto error;
  48         }
  49         msize = attr_fid->clnt->msize;
  50         while (attr_size) {
  51                 if (attr_size > (msize - P9_IOHDRSZ))
  52                         read_count = msize - P9_IOHDRSZ;
  53                 else
  54                         read_count = attr_size;
  55                 read_count = p9_client_read(attr_fid, ((char *)buffer)+offset,
  56                                         NULL, offset, read_count);
  57                 if (read_count < 0) {
  58                         /* error in xattr read */
  59                         retval = read_count;
  60                         goto error;
  61                 }
  62                 offset += read_count;
  63                 attr_size -= read_count;
  64         }
  65         /* Total read xattr bytes */
  66         retval = offset;
  67 error:
  68         if (attr_fid)
  69                 p9_client_clunk(attr_fid);
  70         return retval;
  71
  72 }
  73
  74
  75 /*
  76  * v9fs_xattr_get()
  77  *
  78  * Copy an extended attribute into the buffer
  79  * provided, or compute the buffer size required.
  80  * Buffer is NULL to compute the size of the buffer required.
  81  *
  82  * Returns a negative error number on failure, or the number of bytes
  83  * used / required on success.
  84  */
  85 ssize_t v9fs_xattr_get(struct dentry *dentry, const char *name,
  86                        void *buffer, size_t buffer_size)
  87 {
  88         struct p9_fid *fid;
  89
  90         p9_debug(P9_DEBUG_VFS, "name = %s value_len = %zu\n",
  91                  name, buffer_size);
  92         fid = v9fs_fid_lookup(dentry);
  93         if (IS_ERR(fid))
  94                 return PTR_ERR(fid);
  95
  96         return v9fs_fid_xattr_get(fid, name, buffer, buffer_size);
  97 }
  98
  99 /*
 100  * v9fs_xattr_set()
 101  *
 102  * Create, replace or remove an extended attribute for this inode. Buffer
 103  * is NULL to remove an existing extended attribute, and non-NULL to
 104  * either replace an existing extended attribute, or create a new extended
 105  * attribute. The flags XATTR_REPLACE and XATTR_CREATE
 106  * specify that an extended attribute must exist and must not exist
 107  * previous to the call, respectively.
 108  *
 109  * Returns 0, or a negative error number on failure.
 110  */
 111 int v9fs_xattr_set(struct dentry *dentry, const char *name,
 112                    const void *value, size_t value_len, int flags)
 113 {
 114         struct p9_fid *fid = v9fs_fid_lookup(dentry);
 115         if (IS_ERR(fid))
 116                 return PTR_ERR(fid);
 117         return v9fs_fid_xattr_set(fid, name, value, value_len, flags);
 118 }
 119
 120 int v9fs_fid_xattr_set(struct p9_fid *fid, const char *name,
 121                    const void *value, size_t value_len, int flags)
 122 {
 123         u64 offset = 0;
 124         int retval, msize, write_count;
 125
 126         p9_debug(P9_DEBUG_VFS, "name = %s value_len = %zu flags = %d\n",
 127                  name, value_len, flags);
 128
 129         /* Clone it */
 130         fid = p9_client_walk(fid, 0, NULL, 1);
 131         if (IS_ERR(fid))
 132                 return PTR_ERR(fid);
 133
 134         /*
 135          * On success fid points to xattr
 136          */
 137         retval = p9_client_xattrcreate(fid, name, value_len, flags);
 138         if (retval < 0) {
 139                 p9_debug(P9_DEBUG_VFS, "p9_client_xattrcreate failed %d\n",
 140                          retval);
 141                 p9_client_clunk(fid);
 142                 return retval;
 143         }
 144         msize = fid->clnt->msize;
 145         while (value_len) {
 146                 if (value_len > (msize - P9_IOHDRSZ))
 147                         write_count = msize - P9_IOHDRSZ;
 148                 else
 149                         write_count = value_len;
 150                 write_count = p9_client_write(fid, ((char *)value)+offset,
 151                                         NULL, offset, write_count);
 152                 if (write_count < 0) {
 153                         /* error in xattr write */
 154                         retval = write_count;
 155                         break;
 156                 }
 157                 offset += write_count;
 158                 value_len -= write_count;
 159         }
 160         return p9_client_clunk(fid);
 161 }
 162
 163 ssize_t v9fs_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size)
 164 {
 165         return v9fs_xattr_get(dentry, NULL, buffer, buffer_size);
 166 }
 167
 168 const struct xattr_handler *v9fs_xattr_handlers[] = {
 169         &v9fs_xattr_user_handler,
 170 #ifdef CONFIG_9P_FS_POSIX_ACL
 171         &v9fs_xattr_acl_access_handler,
 172         &v9fs_xattr_acl_default_handler,
 173 #endif
 174         NULL
 175 };