linux/fs/9p/xattr.c
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   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
  24ssize_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;
  67error:
  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 */
  85ssize_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 */
 111int 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
 120int 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
 163ssize_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
 168const struct xattr_handler *v9fs_xattr_handlers[] = {
 169        &v9fs_xattr_user_handler,
 170        &v9fs_xattr_trusted_handler,
 171#ifdef CONFIG_9P_FS_POSIX_ACL
 172        &v9fs_xattr_acl_access_handler,
 173        &v9fs_xattr_acl_default_handler,
 174#endif
 175#ifdef CONFIG_9P_FS_SECURITY
 176        &v9fs_xattr_security_handler,
 177#endif
 178        NULL
 179};
 180
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