[PATCH 12/22 take 3] UBI: update functionality

Artem Bityutskiy
2007-03-14T15:23:13Z

diff -auNrp tmp-from/drivers/mtd/ubi/upd.c tmp-to/drivers/mtd/ubi/upd.c
--- tmp-from/drivers/mtd/ubi/upd.c 1970-01-01 02:00:00.000000000 +0200
+++ tmp-to/drivers/mtd/ubi/upd.c 2007-03-14 17:15:50.000000000 +0200
@@ -0,0 +1,359 @@
+/*
+ * Copyright (c) International Business Machines Corp., 2006
+ * Copyright (C) Nokia Corporation, 2006
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
+ * the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ * Author: Artem B. Bityutskiy
+ *
+ * Jan 2007: Alexander Schmidt, hacked per-volume update.
+ */
+
+/*
+ * This is a part of the user interfaces unit which implements volume update
+ * functionality.
+ *
+ * The update operation is based on the per-volume update marker which is
+ * stored in the volume table. The update marker is set before the update
+ * starts, and removed after the update has been finished. So if the update was
+ * interrupted by an unclean re-boot or due to some other reasons, the update
+ * marker stays on the flash media and UBI finds it when it attaches the MTD
+ * device next time. If there is a set update marker exist for a volume, the
+ * volume is treated as damaged and most I/O operations are prohibited. Only a
+ * new update operation is allowed.
+ *
+ * We do not do any serialization here because the volume update operation is
+ * serialized by opening the volume in the exclusive mode.
+ *
+ * Note, in general it is possible to implement the update operation as a
+ * transaction with a possibility to roll-back. But this is far more complex.
+ * May be in future.
+ */
+
+#include <linux/err.h>
+#include <asm/uaccess.h>
+#include <asm/div64.h>
+#include "ubi.h"
+
+/**
+ * ubi_wipe_out_volume - wipe out an UBI volume.
+ *
+ * @ubi: the UBI device description object
+ * @vol_id: ID of the volume to free
+ *
+ * This function erases all eraseblocks of a volume. Returns zero in case of
+ * success, and a negative error code in case of failure.
+ */
+static int ubi_wipe_out_volume(struct ubi_info *ubi, int vol_id)
+{
+ int i, err;
+ const struct ubi_vtbl_vtr *vtr;
+
+ ubi_assert(vol_id >= 0 && vol_id < ubi->vtbl.vt_slots);
+
+ vtr = ubi_vtbl_get_vtr(ubi, vol_id);
+ for (i = 0; i < vtr->reserved_pebs; i++) {
+ err = ubi_eba_unmap_leb(ubi, vol_id, i);
+ if (unlikely(err))
+ return err;
+ }
+
+ return ubi_wl_flush(ubi);
+}
+
+
+/**
+ * ubi_upd_start - start volume update operation.
+ *
+ * @vol: volume description object
+ * @bytes: how many bytes will be written to the volume
+ *
+ * This function starts a volume update operation. If @bytes is zero, the
+ * volume is just wiped out. This function returns zero in case of success and
+ * a negative error code in case of failure.
+ */
+int ubi_upd_start(struct ubi_uif_volume *vol, long long bytes)
+{
+ int err, rem, vol_id = vol->vol_id;
+ uint64_t tmp;
+ const struct ubi_vtbl_vtr *vtr;
+ struct ubi_info *ubi = vol->ubi;
+
+ dbg_uif("start update of volume %d, %llu bytes", vol_id, bytes);
+
+ ubi_assert(vol_id >= 0 && vol_id < ubi->vtbl.vt_slots);
+ vtr = ubi_vtbl_get_vtr(ubi, vol_id);
+ ubi_assert(!IS_ERR(vtr));
+ ubi_assert(bytes >= 0);
+ ubi_assert(bytes <= vtr->usable_leb_size * vtr->reserved_pebs);
+
+ vol->updating = 1;
+
+ /* Set the update marker first */
+ err = ubi_vtbl_set_upd_marker(ubi, vol_id);
+ if (err)
+ return err;
+
+ /* Before updating - wipe out the volume */
+ err = ubi_wipe_out_volume(ubi, vol_id);
+ if (err)
+ return err;
+
+ if (bytes == 0) {
+ /* Zero bytes means the volume just has to be erased */
+ err = ubi_vtbl_clear_upd_marker(ubi, vol_id, 0);
+ if (!err)
+ vol->updating = 0;
+ return err;
+ }
+
+ vol->upd_buf = kmalloc(ubi->io.leb_size, GFP_KERNEL);
+ if (!vol->upd_buf)
+ return -ENOMEM;
+
+ tmp = bytes;
+ rem = do_div(tmp, vtr->usable_leb_size);
+ vol->upd_ebs = tmp + !!rem;
+ vol->upd_bytes = bytes;
+ vol->upd_received = 0;
+
+ return 0;
+}
+
+/**
+ * write_leb - write update data to a logical eraseblock.
+ *
+ * @ubi: the UBI device description object
+ * @vol_id: ID of the volume to write to
+ * @lnum: logical eraseblock number to write
+ * @buf: data to write
+ * @len: how many bytes to write
+ * @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 a 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 ending 0xFF bytes in case of dynamic volumes is
+ * that we want to make sure that more data may be appended to these logical
+ * eraseblocks in future. Indeed, writing 0xFF bytes may have side effects and
+ * this PEB won't be writable anymore. So if, say, 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.
+ *
+ * The data buffer must always contain @vtr->usable_leb_size bytes, unless this
+ * is the last logical eraseblock.
+ *
+ * This function returns zero in case of success and a negative error code in
+ * case of failure.
+ */
+static int write_leb(struct ubi_info *ubi, int vol_id, int lnum, void *buf,
+ int len, int used_ebs)
+{
+ int err;
+ const struct ubi_vtbl_vtr *vtr;
+
+ vtr = ubi_vtbl_get_vtr(ubi, vol_id);
+ ubi_assert(len >= 0 && len <= vtr->usable_leb_size);
+ ubi_assert(used_ebs >= 0 && used_ebs <= vtr->reserved_pebs);
+
+ if (vtr->vol_type == UBI_DYNAMIC_VOLUME) {
+ int l;
+
+ l = align_up(len, ubi->io.min_io_size);
+ memset(buf + len, 0xFF, l - len);
+
+ l = ubi_calc_data_len(ubi, buf, l);
+ if (l == 0) {
+ dbg_uif("all %d bytes contain 0xFF - skip", len);
+ return 0;
+ }
+ if (len != l)
+ dbg_uif("skip last %d bytes (0xFF)", len - l);
+
+ err = ubi_eba_write_leb(ubi, vol_id, lnum, buf, 0, l,
+ UBI_DATA_UNKNOWN);
+ } else {
+ /*
+ * When writing to static volumes, 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 needs the exact (unaligned) length to store in the
+ * VID header. And it will take 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, vtr->usable_leb_size - len);
+ err = ubi_eba_write_leb_st(ubi, vol_id, lnum, buf, len,
+ UBI_DATA_UNKNOWN, used_ebs);
+ }
+
+ return err;
+}
+
+/**
+ * ubi_upd_write_data - write more data.
+ *
+ * @vol: volume description object
+ * @buf: the data to write (user-space memory buffer)
+ * @count: how much bytes to write
+ *
+ * This function writes more data to the volume which is being updated. It may
+ * be called arbitrary number of times until all of the update data arrive.
+ * This function returns %0 in case of success, a positive number of bytes
+ * written at during this last call if the whole volume update was successfully
+ * finished, and a negative error code in case of failure.
+ */
+int ubi_upd_write_data(struct ubi_uif_volume *vol, const void __user *buf,
+ int count)
+{
+ uint64_t tmp;
+ const struct ubi_vtbl_vtr *vtr;
+ struct ubi_info *ubi = vol->ubi;
+ int lnum, offs, err = 0, len, to_write = count, vol_id = vol->vol_id;
+
+ dbg_uif("write %d bytes requested", count);
+
+ ubi_assert(vol_id >= 0 && vol_id < ubi->vtbl.vt_slots);
+ ubi_assert(count >= 0);
+ vtr = ubi_vtbl_get_vtr(ubi, vol_id);
+ ubi_assert(!IS_ERR(vtr));
+
+ if (unlikely(count == 0))
+ return 0;
+
+ ubi_assert(vol->updating == 1);
+ ubi_assert(vol->upd_received >= 0);
+ ubi_assert(vol->upd_received < vol->upd_bytes);
+
+ tmp = vol->upd_received;
+ offs = do_div(tmp, vtr->usable_leb_size);
+ lnum = tmp;
+
+ if (vol->upd_received + count > vol->upd_bytes)
+ to_write = count = vol->upd_bytes - vol->upd_received;
+
+ /*
+ * When updating volumes, we accumulate whole logical eraseblock data
+ * and write it at once.
+ */
+
+ if (offs != 0) {
+ /*
+ * This is a write to the middle of the logical eraseblock. We
+ * copy the data to our update buffer and wait for more data or
+ * flush it if the whole eraseblock is written or the update
+ * is finished.
+ */
+
+ len = vtr->usable_leb_size - offs;
+ if (len > count)
+ len = count;
+
+ dbg_uif("copy more %d bytes of data", len);
+
+ err = copy_from_user(vol->upd_buf + offs, buf, len);
+ if (unlikely(err)) {
+ dbg_err("memory access error");
+ return -EFAULT;
+ }
+
+ if (offs + len == vtr->usable_leb_size ||
+ vol->upd_received + len == vol->upd_bytes) {
+ int flush_len = offs + len;
+
+ /*
+ * OK, we gathered either the whole eraseblock or this
+ * is the last chunk, it's time to flush our buffer.
+ */
+
+ ubi_assert(flush_len <= vtr->usable_leb_size);
+
+ err = write_leb(ubi, vol_id, lnum, vol->upd_buf,
+ flush_len, vol->upd_ebs);
+ if (err)
+ return err;
+ }
+
+ vol->upd_received += len;
+ count -= len;
+ buf += len;
+ lnum += 1;
+ }
+
+ /*
+ * If we've got more to write, let's continue. At this point we know we
+ * are starting from the beginning of an eraseblock.
+ */
+
+ while (count) {
+ if (count > vtr->usable_leb_size)
+ len = vtr->usable_leb_size;
+ else
+ len = count;
+
+ dbg_uif("copy %d bytes of user data", len);
+ err = copy_from_user(vol->upd_buf, buf, len);
+ if (unlikely(err)) {
+ dbg_err("memory access error");
+ return -EFAULT;
+ }
+
+ if (len == vtr->usable_leb_size ||
+ vol->upd_received + len == vol->upd_bytes) {
+ err = write_leb(ubi, vol_id, lnum, vol->upd_buf, len,
+ vol->upd_ebs);
+ if (unlikely(err))
+ break;
+ }
+
+ vol->upd_received += len;
+ count -= len;
+ lnum += 1;
+ buf += len;
+ }
+
+ ubi_assert(vol->upd_received <= vol->upd_bytes);
+ if (vol->upd_received == vol->upd_bytes) {
+ /* The update is finished, clear the update marker */
+ err = ubi_vtbl_clear_upd_marker(ubi, vol_id, vol->upd_bytes);
+ if (err == 0) {
+ err = to_write;
+ kfree(vol->upd_buf);
+ vol->updating = 0;
+ }
+ }
+
+ return err;
+}
+
+/**
+ * ubi_upd_abort - abort volume update.
+ *
+ * @vol: volume description object
+ */
+void ubi_upd_abort(struct ubi_uif_volume *vol)
+{
+ ubi_warn("update of volume %d was not finished, volume is damaged",
+ vol->vol_id);
+ vol->updating = 0;
+ kfree(vol->upd_buf);
+}