xattr.c

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/*
 * Copyright IBM Corporation, 2010
 * Author Aneesh Kumar K.V <[email protected]>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of version 2.1 of the GNU Lesser General Public License
 * as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it would be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 *
 */

#include <linux/module.h>
#include <linux/fs.h>
#include <linux/sched.h>
#include <net/9p/9p.h>
#include <net/9p/client.h>

#include "fid.h"
#include "xattr.h"

ssize_t v9fs_fid_xattr_get(struct p9_fid *fid, const char *name,
               void *buffer, size_t buffer_size)
{
    ssize_t retval;
    int msize, read_count;
    u64 offset = 0, attr_size;
    struct p9_fid *attr_fid;

    attr_fid = p9_client_xattrwalk(fid, name, &attr_size);
    if (IS_ERR(attr_fid)) {
        retval = PTR_ERR(attr_fid);
        p9_debug(P9_DEBUG_VFS, "p9_client_attrwalk failed %zd\n",
             retval);
        attr_fid = NULL;
        goto error;
    }
    if (!buffer_size) {
        /* request to get the attr_size */
        retval = attr_size;
        goto error;
    }
    if (attr_size > buffer_size) {
        retval = -ERANGE;
        goto error;
    }
    msize = attr_fid->clnt->msize;
    while (attr_size) {
        if (attr_size > (msize - P9_IOHDRSZ))
            read_count = msize - P9_IOHDRSZ;
        else
            read_count = attr_size;
        read_count = p9_client_read(attr_fid, ((char *)buffer)+offset,
                    NULL, offset, read_count);
        if (read_count < 0) {
            /* error in xattr read */
            retval = read_count;
            goto error;
        }
        offset += read_count;
        attr_size -= read_count;
    }
    /* Total read xattr bytes */
    retval = offset;
error:
    if (attr_fid)
        p9_client_clunk(attr_fid);
    return retval;

}


/*
 * v9fs_xattr_get()
 *
 * Copy an extended attribute into the buffer
 * provided, or compute the buffer size required.
 * Buffer is NULL to compute the size of the buffer required.
 *
 * Returns a negative error number on failure, or the number of bytes
 * used / required on success.
 */
ssize_t v9fs_xattr_get(struct dentry *dentry, const char *name,
               void *buffer, size_t buffer_size)
{
    struct p9_fid *fid;

    p9_debug(P9_DEBUG_VFS, "name = %s value_len = %zu\n",
         name, buffer_size);
    fid = v9fs_fid_lookup(dentry);
    if (IS_ERR(fid))
        return PTR_ERR(fid);

    return v9fs_fid_xattr_get(fid, name, buffer, buffer_size);
}

/*
 * v9fs_xattr_set()
 *
 * Create, replace or remove an extended attribute for this inode. Buffer
 * is NULL to remove an existing extended attribute, and non-NULL to
 * either replace an existing extended attribute, or create a new extended
 * attribute. The flags XATTR_REPLACE and XATTR_CREATE
 * specify that an extended attribute must exist and must not exist
 * previous to the call, respectively.
 *
 * Returns 0, or a negative error number on failure.
 */
int v9fs_xattr_set(struct dentry *dentry, const char *name,
           const void *value, size_t value_len, int flags)
{
    u64 offset = 0;
    int retval, msize, write_count;
    struct p9_fid *fid = NULL;

    p9_debug(P9_DEBUG_VFS, "name = %s value_len = %zu flags = %d\n",
         name, value_len, flags);

    fid = v9fs_fid_clone(dentry);
    if (IS_ERR(fid)) {
        retval = PTR_ERR(fid);
        fid = NULL;
        goto error;
    }
    /*
     * On success fid points to xattr
     */
    retval = p9_client_xattrcreate(fid, name, value_len, flags);
    if (retval < 0) {
        p9_debug(P9_DEBUG_VFS, "p9_client_xattrcreate failed %d\n",
             retval);
        goto error;
    }
    msize = fid->clnt->msize;
    while (value_len) {
        if (value_len > (msize - P9_IOHDRSZ))
            write_count = msize - P9_IOHDRSZ;
        else
            write_count = value_len;
        write_count = p9_client_write(fid, ((char *)value)+offset,
                    NULL, offset, write_count);
        if (write_count < 0) {
            /* error in xattr write */
            retval = write_count;
            goto error;
        }
        offset += write_count;
        value_len -= write_count;
    }
    /* Total read xattr bytes */
    retval = offset;
error:
    if (fid)
        retval = p9_client_clunk(fid);
    return retval;
}

ssize_t v9fs_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size)
{
    return v9fs_xattr_get(dentry, NULL, buffer, buffer_size);
}

const struct xattr_handler *v9fs_xattr_handlers[] = {
    &v9fs_xattr_user_handler,
#ifdef CONFIG_9P_FS_POSIX_ACL
    &v9fs_xattr_acl_access_handler,
    &v9fs_xattr_acl_default_handler,
#endif
    NULL
};