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        u64 offset = 0;
 115        int retval, msize, write_count;
 116        struct p9_fid *fid = NULL;
 117
 118        p9_debug(P9_DEBUG_VFS, "name = %s value_len = %zu flags = %d\n",
 119                 name, value_len, flags);
 120
 121        fid = v9fs_fid_clone(dentry);
 122        if (IS_ERR(fid)) {
 123                retval = PTR_ERR(fid);
 124                fid = NULL;
 125                goto error;
 126        }
 127        /*
 128         * On success fid points to xattr
 129         */
 130        retval = p9_client_xattrcreate(fid, name, value_len, flags);
 131        if (retval < 0) {
 132                p9_debug(P9_DEBUG_VFS, "p9_client_xattrcreate failed %d\n",
 133                         retval);
 134                goto error;
 135        }
 136        msize = fid->clnt->msize;
 137        while (value_len) {
 138                if (value_len > (msize - P9_IOHDRSZ))
 139                        write_count = msize - P9_IOHDRSZ;
 140                else
 141                        write_count = value_len;
 142                write_count = p9_client_write(fid, ((char *)value)+offset,
 143                                        NULL, offset, write_count);
 144                if (write_count < 0) {
 145                        /* error in xattr write */
 146                        retval = write_count;
 147                        goto error;
 148                }
 149                offset += write_count;
 150                value_len -= write_count;
 151        }
 152        /* Total read xattr bytes */
 153        retval = offset;
 154error:
 155        if (fid)
 156                retval = p9_client_clunk(fid);
 157        return retval;
 158}
 159
 160ssize_t v9fs_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size)
 161{
 162        return v9fs_xattr_get(dentry, NULL, buffer, buffer_size);
 163}
 164
 165const struct xattr_handler *v9fs_xattr_handlers[] = {
 166        &v9fs_xattr_user_handler,
 167#ifdef CONFIG_9P_FS_POSIX_ACL
 168        &v9fs_xattr_acl_access_handler,
 169        &v9fs_xattr_acl_default_handler,
 170#endif
 171        NULL
 172};
 173
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