/**
* write_leb - write update data.
* @ubi: UBI device description object
* @vol: volume description object
* @lnum: logical eraseblock number
* @buf: data to write
* @len: data size
* @used_ebs: how many logical eraseblocks will this volume contain (static
* volumes only)
*
* This function writes update data to corresponding logical eraseblock. In
* case of dynamic volume, this function checks if the data contains 0xFF bytes
* at the end. If yes, the 0xFF bytes are cut and not written. So if the whole
* buffer contains only 0xFF bytes, the LEB is left unmapped.
*
* The reason why we skip the trailing 0xFF bytes in case of dynamic volume is
* that we want to make sure that more data may be appended to the logical
* eraseblock in future. Indeed, writing 0xFF bytes may have side effects and
* this PEB won't be writable anymore. So if one writes the file-system image
* to the UBI volume where 0xFFs mean free space - UBI makes sure this free
* space is writable after the update.
*
* We do not do this for static volumes because they are read-only. But this
* also cannot be done because we have to store per-LEB CRC and the correct
* data length.
*
* This function returns zero in case of success and a negative error code in
* case of failure.
*/
static int write_leb(struct ubi_device *ubi, struct ubi_volume *vol, int lnum,
void *buf, int len, int used_ebs)
{
int err;
if (vol->vol_type == UBI_DYNAMIC_VOLUME) {
int l = ALIGN(len, ubi->min_io_size);
memset(buf + len, 0xFF, l - len);
len = ubi_calc_data_len(ubi, buf, l);
if (len == 0) {
dbg_gen("all %d bytes contain 0xFF - skip", len);
return 0;
}
err = ubi_eba_write_leb(ubi, vol, lnum, buf, 0, len);
} else {
/*
* When writing static volume, and this is the last logical
* eraseblock, the length (@len) does not have to be aligned to
* the minimal flash I/O unit. The 'ubi_eba_write_leb_st()'
* function accepts exact (unaligned) length and stores it in
* the VID header. And it takes care of proper alignment by
* padding the buffer. Here we just make sure the padding will
* contain zeros, not random trash.
*/
memset(buf + len, 0, vol->usable_leb_size - len);
err = ubi_eba_write_leb_st(ubi, vol, lnum, buf, len, used_ebs);
}
return err;
}
static int write_leb(struct ubi_device *ubi, struct ubi_volume *vol, int lnum,
void *buf, int len, int used_ebs)
{
int err;
if (vol->vol_type == UBI_DYNAMIC_VOLUME) {
int l = ALIGN(len, ubi->min_io_size);
memset(buf + len, 0xFF, l - len);
len = ubi_calc_data_len(ubi, buf, l);
if (len == 0) {
dbg_gen("all %d bytes contain 0xFF - skip", len);
return 0;
}
err = ubi_eba_write_leb(ubi, vol, lnum, buf, 0, len,
UBI_UNKNOWN);
} else {
memset(buf + len, 0, vol->usable_leb_size - len);
err = ubi_eba_write_leb_st(ubi, vol, lnum, buf, len,
UBI_UNKNOWN, used_ebs);
}
return err;
}
/**
* ubi_more_leb_change_data - accept more data for atomic LEB change.
* @ubi: UBI device description object
* @vol: volume description object
* @buf: write data (user-space memory buffer)
* @count: how much bytes to write
*
* This function accepts more data to the volume which is being under the
* "atomic LEB change" operation. It may be called arbitrary number of times
* until all data arrives. This function returns %0 in case of success, number
* of bytes written during the last call if the whole "atomic LEB change"
* operation has been successfully finished, and a negative error code in case
* of failure.
*/
int ubi_more_leb_change_data(struct ubi_device *ubi, struct ubi_volume *vol,
const void __user *buf, int count)
{
int err;
dbg_gen("write %d of %lld bytes, %lld already passed",
count, vol->upd_bytes, vol->upd_received);
if (ubi->ro_mode)
return -EROFS;
if (vol->upd_received + count > vol->upd_bytes)
count = vol->upd_bytes - vol->upd_received;
err = copy_from_user(vol->upd_buf + vol->upd_received, buf, count);
if (err)
return -EFAULT;
vol->upd_received += count;
if (vol->upd_received == vol->upd_bytes) {
int len = ALIGN((int)vol->upd_bytes, ubi->min_io_size);
memset(vol->upd_buf + vol->upd_bytes, 0xFF,
len - vol->upd_bytes);
len = ubi_calc_data_len(ubi, vol->upd_buf, len);
err = ubi_eba_atomic_leb_change(ubi, vol, vol->ch_lnum,
vol->upd_buf, len);
if (err)
return err;
}
ubi_assert(vol->upd_received <= vol->upd_bytes);
if (vol->upd_received == vol->upd_bytes) {
vol->changing_leb = 0;
err = count;
vfree(vol->upd_buf);
}
return err;
}
