release/src-rt-6.x.4708/linux/linux-2.6.36/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 /*
  25  * v9fs_xattr_get()
  26  *
  27  * Copy an extended attribute into the buffer
  28  * provided, or compute the buffer size required.
  29  * Buffer is NULL to compute the size of the buffer required.
  30  *
  31  * Returns a negative error number on failure, or the number of bytes
  32  * used / required on success.
  33  */
  34 ssize_t v9fs_xattr_get(struct dentry *dentry, const char *name,
  35                        void *buffer, size_t buffer_size)
  36 {
  37         ssize_t retval;
  38         int msize, read_count;
  39         u64 offset = 0, attr_size;
  40         struct p9_fid *fid, *attr_fid;
  41
  42         P9_DPRINTK(P9_DEBUG_VFS, "%s: name = %s value_len = %zu\n",
  43                 __func__, name, buffer_size);
  44
  45         fid = v9fs_fid_lookup(dentry);
  46         if (IS_ERR(fid))
  47                 return PTR_ERR(fid);
  48
  49         attr_fid = p9_client_xattrwalk(fid, name, &attr_size);
  50         if (IS_ERR(attr_fid)) {
  51                 retval = PTR_ERR(attr_fid);
  52                 P9_DPRINTK(P9_DEBUG_VFS,
  53                         "p9_client_attrwalk failed %zd\n", retval);
  54                 attr_fid = NULL;
  55                 goto error;
  56         }
  57         if (!buffer_size) {
  58                 /* request to get the attr_size */
  59                 retval = attr_size;
  60                 goto error;
  61         }
  62         if (attr_size > buffer_size) {
  63                 retval = -ERANGE;
  64                 goto error;
  65         }
  66         msize = attr_fid->clnt->msize;
  67         while (attr_size) {
  68                 if (attr_size > (msize - P9_IOHDRSZ))
  69                         read_count = msize - P9_IOHDRSZ;
  70                 else
  71                         read_count = attr_size;
  72                 read_count = p9_client_read(attr_fid, ((char *)buffer)+offset,
  73                                         NULL, offset, read_count);
  74                 if (read_count < 0) {
  75                         /* error in xattr read */
  76                         retval = read_count;
  77                         goto error;
  78                 }
  79                 offset += read_count;
  80                 attr_size -= read_count;
  81         }
  82         /* Total read xattr bytes */
  83         retval = offset;
  84 error:
  85         if (attr_fid)
  86                 p9_client_clunk(attr_fid);
  87         return retval;
  88
  89 }
  90
  91 /*
  92  * v9fs_xattr_set()
  93  *
  94  * Create, replace or remove an extended attribute for this inode. Buffer
  95  * is NULL to remove an existing extended attribute, and non-NULL to
  96  * either replace an existing extended attribute, or create a new extended
  97  * attribute. The flags XATTR_REPLACE and XATTR_CREATE
  98  * specify that an extended attribute must exist and must not exist
  99  * previous to the call, respectively.
 100  *
 101  * Returns 0, or a negative error number on failure.
 102  */
 103 int v9fs_xattr_set(struct dentry *dentry, const char *name,
 104                    const void *value, size_t value_len, int flags)
 105 {
 106         u64 offset = 0;
 107         int retval, msize, write_count;
 108         struct p9_fid *fid = NULL;
 109
 110         P9_DPRINTK(P9_DEBUG_VFS, "%s: name = %s value_len = %zu flags = %d\n",
 111                 __func__, name, value_len, flags);
 112
 113         fid = v9fs_fid_clone(dentry);
 114         if (IS_ERR(fid)) {
 115                 retval = PTR_ERR(fid);
 116                 fid = NULL;
 117                 goto error;
 118         }
 119         /*
 120          * On success fid points to xattr
 121          */
 122         retval = p9_client_xattrcreate(fid, name, value_len, flags);
 123         if (retval < 0) {
 124                 P9_DPRINTK(P9_DEBUG_VFS,
 125                         "p9_client_xattrcreate failed %d\n", retval);
 126                 goto error;
 127         }
 128         msize = fid->clnt->msize;;
 129         while (value_len) {
 130                 if (value_len > (msize - P9_IOHDRSZ))
 131                         write_count = msize - P9_IOHDRSZ;
 132                 else
 133                         write_count = value_len;
 134                 write_count = p9_client_write(fid, ((char *)value)+offset,
 135                                         NULL, offset, write_count);
 136                 if (write_count < 0) {
 137                         /* error in xattr write */
 138                         retval = write_count;
 139                         goto error;
 140                 }
 141                 offset += write_count;
 142                 value_len -= write_count;
 143         }
 144         /* Total read xattr bytes */
 145         retval = offset;
 146 error:
 147         if (fid)
 148                 retval = p9_client_clunk(fid);
 149         return retval;
 150 }
 151
 152 ssize_t v9fs_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size)
 153 {
 154         return v9fs_xattr_get(dentry, NULL, buffer, buffer_size);
 155 }
 156
 157 const struct xattr_handler *v9fs_xattr_handlers[] = {
 158         &v9fs_xattr_user_handler,
 159         NULL
 160 };