io.c 33.1 KB
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/*
 * This file is part of UBIFS.
 *
 * Copyright (C) 2006-2008 Nokia Corporation.
 * Copyright (C) 2006, 2007 University of Szeged, Hungary
 *
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 * SPDX-License-Identifier:	GPL-2.0+
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 *
 * Authors: Artem Bityutskiy (Битюцкий Артём)
 *          Adrian Hunter
 *          Zoltan Sogor
 */

/*
 * This file implements UBIFS I/O subsystem which provides various I/O-related
 * helper functions (reading/writing/checking/validating nodes) and implements
 * write-buffering support. Write buffers help to save space which otherwise
 * would have been wasted for padding to the nearest minimal I/O unit boundary.
 * Instead, data first goes to the write-buffer and is flushed when the
 * buffer is full or when it is not used for some time (by timer). This is
 * similar to the mechanism is used by JFFS2.
 *
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 * UBIFS distinguishes between minimum write size (@c->min_io_size) and maximum
 * write size (@c->max_write_size). The latter is the maximum amount of bytes
 * the underlying flash is able to program at a time, and writing in
 * @c->max_write_size units should presumably be faster. Obviously,
 * @c->min_io_size <= @c->max_write_size. Write-buffers are of
 * @c->max_write_size bytes in size for maximum performance. However, when a
 * write-buffer is flushed, only the portion of it (aligned to @c->min_io_size
 * boundary) which contains data is written, not the whole write-buffer,
 * because this is more space-efficient.
 *
 * This optimization adds few complications to the code. Indeed, on the one
 * hand, we want to write in optimal @c->max_write_size bytes chunks, which
 * also means aligning writes at the @c->max_write_size bytes offsets. On the
 * other hand, we do not want to waste space when synchronizing the write
 * buffer, so during synchronization we writes in smaller chunks. And this makes
 * the next write offset to be not aligned to @c->max_write_size bytes. So the
 * have to make sure that the write-buffer offset (@wbuf->offs) becomes aligned
 * to @c->max_write_size bytes again. We do this by temporarily shrinking
 * write-buffer size (@wbuf->size).
 *
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 * Write-buffers are defined by 'struct ubifs_wbuf' objects and protected by
 * mutexes defined inside these objects. Since sometimes upper-level code
 * has to lock the write-buffer (e.g. journal space reservation code), many
 * functions related to write-buffers have "nolock" suffix which means that the
 * caller has to lock the write-buffer before calling this function.
 *
 * UBIFS stores nodes at 64 bit-aligned addresses. If the node length is not
 * aligned, UBIFS starts the next node from the aligned address, and the padded
 * bytes may contain any rubbish. In other words, UBIFS does not put padding
 * bytes in those small gaps. Common headers of nodes store real node lengths,
 * not aligned lengths. Indexing nodes also store real lengths in branches.
 *
 * UBIFS uses padding when it pads to the next min. I/O unit. In this case it
 * uses padding nodes or padding bytes, if the padding node does not fit.
 *
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 * All UBIFS nodes are protected by CRC checksums and UBIFS checks CRC when
 * they are read from the flash media.
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 */

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#ifndef __UBOOT__
#include <linux/crc32.h>
#include <linux/slab.h>
#else
#include <linux/compat.h>
#include <linux/err.h>
#endif
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#include "ubifs.h"

/**
 * ubifs_ro_mode - switch UBIFS to read read-only mode.
 * @c: UBIFS file-system description object
 * @err: error code which is the reason of switching to R/O mode
 */
void ubifs_ro_mode(struct ubifs_info *c, int err)
{
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	if (!c->ro_error) {
		c->ro_error = 1;
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		c->no_chk_data_crc = 0;
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		c->vfs_sb->s_flags |= MS_RDONLY;
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		ubifs_warn(c, "switched to read-only mode, error %d", err);
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		dump_stack();
	}
}

/*
 * Below are simple wrappers over UBI I/O functions which include some
 * additional checks and UBIFS debugging stuff. See corresponding UBI function
 * for more information.
 */

int ubifs_leb_read(const struct ubifs_info *c, int lnum, void *buf, int offs,
		   int len, int even_ebadmsg)
{
	int err;

	err = ubi_read(c->ubi, lnum, buf, offs, len);
	/*
	 * In case of %-EBADMSG print the error message only if the
	 * @even_ebadmsg is true.
	 */
	if (err && (err != -EBADMSG || even_ebadmsg)) {
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		ubifs_err(c, "reading %d bytes from LEB %d:%d failed, error %d",
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			  len, lnum, offs, err);
		dump_stack();
	}
	return err;
}

int ubifs_leb_write(struct ubifs_info *c, int lnum, const void *buf, int offs,
		    int len)
{
	int err;

	ubifs_assert(!c->ro_media && !c->ro_mount);
	if (c->ro_error)
		return -EROFS;
	if (!dbg_is_tst_rcvry(c))
		err = ubi_leb_write(c->ubi, lnum, buf, offs, len);
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#ifndef __UBOOT__
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	else
		err = dbg_leb_write(c, lnum, buf, offs, len);
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#endif
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	if (err) {
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		ubifs_err(c, "writing %d bytes to LEB %d:%d failed, error %d",
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			  len, lnum, offs, err);
		ubifs_ro_mode(c, err);
		dump_stack();
	}
	return err;
}

int ubifs_leb_change(struct ubifs_info *c, int lnum, const void *buf, int len)
{
	int err;

	ubifs_assert(!c->ro_media && !c->ro_mount);
	if (c->ro_error)
		return -EROFS;
	if (!dbg_is_tst_rcvry(c))
		err = ubi_leb_change(c->ubi, lnum, buf, len);
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#ifndef __UBOOT__
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	else
		err = dbg_leb_change(c, lnum, buf, len);
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#endif
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	if (err) {
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		ubifs_err(c, "changing %d bytes in LEB %d failed, error %d",
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			  len, lnum, err);
		ubifs_ro_mode(c, err);
		dump_stack();
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	}
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	return err;
}

int ubifs_leb_unmap(struct ubifs_info *c, int lnum)
{
	int err;

	ubifs_assert(!c->ro_media && !c->ro_mount);
	if (c->ro_error)
		return -EROFS;
	if (!dbg_is_tst_rcvry(c))
		err = ubi_leb_unmap(c->ubi, lnum);
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#ifndef __UBOOT__
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	else
		err = dbg_leb_unmap(c, lnum);
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#endif
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	if (err) {
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		ubifs_err(c, "unmap LEB %d failed, error %d", lnum, err);
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		ubifs_ro_mode(c, err);
		dump_stack();
	}
	return err;
}

int ubifs_leb_map(struct ubifs_info *c, int lnum)
{
	int err;

	ubifs_assert(!c->ro_media && !c->ro_mount);
	if (c->ro_error)
		return -EROFS;
	if (!dbg_is_tst_rcvry(c))
		err = ubi_leb_map(c->ubi, lnum);
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#ifndef __UBOOT__
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	else
		err = dbg_leb_map(c, lnum);
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#endif
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	if (err) {
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		ubifs_err(c, "mapping LEB %d failed, error %d", lnum, err);
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		ubifs_ro_mode(c, err);
		dump_stack();
	}
	return err;
}

int ubifs_is_mapped(const struct ubifs_info *c, int lnum)
{
	int err;

	err = ubi_is_mapped(c->ubi, lnum);
	if (err < 0) {
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		ubifs_err(c, "ubi_is_mapped failed for LEB %d, error %d",
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			  lnum, err);
		dump_stack();
	}
	return err;
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}

/**
 * ubifs_check_node - check node.
 * @c: UBIFS file-system description object
 * @buf: node to check
 * @lnum: logical eraseblock number
 * @offs: offset within the logical eraseblock
 * @quiet: print no messages
 * @must_chk_crc: indicates whether to always check the CRC
 *
 * This function checks node magic number and CRC checksum. This function also
 * validates node length to prevent UBIFS from becoming crazy when an attacker
 * feeds it a file-system image with incorrect nodes. For example, too large
 * node length in the common header could cause UBIFS to read memory outside of
 * allocated buffer when checking the CRC checksum.
 *
 * This function may skip data nodes CRC checking if @c->no_chk_data_crc is
 * true, which is controlled by corresponding UBIFS mount option. However, if
 * @must_chk_crc is true, then @c->no_chk_data_crc is ignored and CRC is
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 * checked. Similarly, if @c->mounting or @c->remounting_rw is true (we are
 * mounting or re-mounting to R/W mode), @c->no_chk_data_crc is ignored and CRC
 * is checked. This is because during mounting or re-mounting from R/O mode to
 * R/W mode we may read journal nodes (when replying the journal or doing the
 * recovery) and the journal nodes may potentially be corrupted, so checking is
 * required.
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 *
 * This function returns zero in case of success and %-EUCLEAN in case of bad
 * CRC or magic.
 */
int ubifs_check_node(const struct ubifs_info *c, const void *buf, int lnum,
		     int offs, int quiet, int must_chk_crc)
{
	int err = -EINVAL, type, node_len;
	uint32_t crc, node_crc, magic;
	const struct ubifs_ch *ch = buf;

	ubifs_assert(lnum >= 0 && lnum < c->leb_cnt && offs >= 0);
	ubifs_assert(!(offs & 7) && offs < c->leb_size);

	magic = le32_to_cpu(ch->magic);
	if (magic != UBIFS_NODE_MAGIC) {
		if (!quiet)
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			ubifs_err(c, "bad magic %#08x, expected %#08x",
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				  magic, UBIFS_NODE_MAGIC);
		err = -EUCLEAN;
		goto out;
	}

	type = ch->node_type;
	if (type < 0 || type >= UBIFS_NODE_TYPES_CNT) {
		if (!quiet)
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			ubifs_err(c, "bad node type %d", type);
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		goto out;
	}

	node_len = le32_to_cpu(ch->len);
	if (node_len + offs > c->leb_size)
		goto out_len;

	if (c->ranges[type].max_len == 0) {
		if (node_len != c->ranges[type].len)
			goto out_len;
	} else if (node_len < c->ranges[type].min_len ||
		   node_len > c->ranges[type].max_len)
		goto out_len;

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	if (!must_chk_crc && type == UBIFS_DATA_NODE && !c->mounting &&
	    !c->remounting_rw && c->no_chk_data_crc)
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		return 0;

	crc = crc32(UBIFS_CRC32_INIT, buf + 8, node_len - 8);
	node_crc = le32_to_cpu(ch->crc);
	if (crc != node_crc) {
		if (!quiet)
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			ubifs_err(c, "bad CRC: calculated %#08x, read %#08x",
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				  crc, node_crc);
		err = -EUCLEAN;
		goto out;
	}

	return 0;

out_len:
	if (!quiet)
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		ubifs_err(c, "bad node length %d", node_len);
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out:
	if (!quiet) {
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		ubifs_err(c, "bad node at LEB %d:%d", lnum, offs);
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		ubifs_dump_node(c, buf);
		dump_stack();
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	}
	return err;
}

/**
 * ubifs_pad - pad flash space.
 * @c: UBIFS file-system description object
 * @buf: buffer to put padding to
 * @pad: how many bytes to pad
 *
 * The flash media obliges us to write only in chunks of %c->min_io_size and
 * when we have to write less data we add padding node to the write-buffer and
 * pad it to the next minimal I/O unit's boundary. Padding nodes help when the
 * media is being scanned. If the amount of wasted space is not enough to fit a
 * padding node which takes %UBIFS_PAD_NODE_SZ bytes, we write padding bytes
 * pattern (%UBIFS_PADDING_BYTE).
 *
 * Padding nodes are also used to fill gaps when the "commit-in-gaps" method is
 * used.
 */
void ubifs_pad(const struct ubifs_info *c, void *buf, int pad)
{
	uint32_t crc;

	ubifs_assert(pad >= 0 && !(pad & 7));

	if (pad >= UBIFS_PAD_NODE_SZ) {
		struct ubifs_ch *ch = buf;
		struct ubifs_pad_node *pad_node = buf;

		ch->magic = cpu_to_le32(UBIFS_NODE_MAGIC);
		ch->node_type = UBIFS_PAD_NODE;
		ch->group_type = UBIFS_NO_NODE_GROUP;
		ch->padding[0] = ch->padding[1] = 0;
		ch->sqnum = 0;
		ch->len = cpu_to_le32(UBIFS_PAD_NODE_SZ);
		pad -= UBIFS_PAD_NODE_SZ;
		pad_node->pad_len = cpu_to_le32(pad);
		crc = crc32(UBIFS_CRC32_INIT, buf + 8, UBIFS_PAD_NODE_SZ - 8);
		ch->crc = cpu_to_le32(crc);
		memset(buf + UBIFS_PAD_NODE_SZ, 0, pad);
	} else if (pad > 0)
		/* Too little space, padding node won't fit */
		memset(buf, UBIFS_PADDING_BYTE, pad);
}

/**
 * next_sqnum - get next sequence number.
 * @c: UBIFS file-system description object
 */
static unsigned long long next_sqnum(struct ubifs_info *c)
{
	unsigned long long sqnum;

	spin_lock(&c->cnt_lock);
	sqnum = ++c->max_sqnum;
	spin_unlock(&c->cnt_lock);

	if (unlikely(sqnum >= SQNUM_WARN_WATERMARK)) {
		if (sqnum >= SQNUM_WATERMARK) {
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			ubifs_err(c, "sequence number overflow %llu, end of life",
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				  sqnum);
			ubifs_ro_mode(c, -EINVAL);
		}
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		ubifs_warn(c, "running out of sequence numbers, end of life soon");
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	}

	return sqnum;
}

/**
 * ubifs_prepare_node - prepare node to be written to flash.
 * @c: UBIFS file-system description object
 * @node: the node to pad
 * @len: node length
 * @pad: if the buffer has to be padded
 *
 * This function prepares node at @node to be written to the media - it
 * calculates node CRC, fills the common header, and adds proper padding up to
 * the next minimum I/O unit if @pad is not zero.
 */
void ubifs_prepare_node(struct ubifs_info *c, void *node, int len, int pad)
{
	uint32_t crc;
	struct ubifs_ch *ch = node;
	unsigned long long sqnum = next_sqnum(c);

	ubifs_assert(len >= UBIFS_CH_SZ);

	ch->magic = cpu_to_le32(UBIFS_NODE_MAGIC);
	ch->len = cpu_to_le32(len);
	ch->group_type = UBIFS_NO_NODE_GROUP;
	ch->sqnum = cpu_to_le64(sqnum);
	ch->padding[0] = ch->padding[1] = 0;
	crc = crc32(UBIFS_CRC32_INIT, node + 8, len - 8);
	ch->crc = cpu_to_le32(crc);

	if (pad) {
		len = ALIGN(len, 8);
		pad = ALIGN(len, c->min_io_size) - len;
		ubifs_pad(c, node + len, pad);
	}
}

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/**
 * ubifs_prep_grp_node - prepare node of a group to be written to flash.
 * @c: UBIFS file-system description object
 * @node: the node to pad
 * @len: node length
 * @last: indicates the last node of the group
 *
 * This function prepares node at @node to be written to the media - it
 * calculates node CRC and fills the common header.
 */
void ubifs_prep_grp_node(struct ubifs_info *c, void *node, int len, int last)
{
	uint32_t crc;
	struct ubifs_ch *ch = node;
	unsigned long long sqnum = next_sqnum(c);

	ubifs_assert(len >= UBIFS_CH_SZ);

	ch->magic = cpu_to_le32(UBIFS_NODE_MAGIC);
	ch->len = cpu_to_le32(len);
	if (last)
		ch->group_type = UBIFS_LAST_OF_NODE_GROUP;
	else
		ch->group_type = UBIFS_IN_NODE_GROUP;
	ch->sqnum = cpu_to_le64(sqnum);
	ch->padding[0] = ch->padding[1] = 0;
	crc = crc32(UBIFS_CRC32_INIT, node + 8, len - 8);
	ch->crc = cpu_to_le32(crc);
}

#ifndef __UBOOT__
/**
 * wbuf_timer_callback - write-buffer timer callback function.
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 * @timer: timer data (write-buffer descriptor)
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 *
 * This function is called when the write-buffer timer expires.
 */
static enum hrtimer_restart wbuf_timer_callback_nolock(struct hrtimer *timer)
{
	struct ubifs_wbuf *wbuf = container_of(timer, struct ubifs_wbuf, timer);

	dbg_io("jhead %s", dbg_jhead(wbuf->jhead));
	wbuf->need_sync = 1;
	wbuf->c->need_wbuf_sync = 1;
	ubifs_wake_up_bgt(wbuf->c);
	return HRTIMER_NORESTART;
}

/**
 * new_wbuf_timer - start new write-buffer timer.
 * @wbuf: write-buffer descriptor
 */
static void new_wbuf_timer_nolock(struct ubifs_wbuf *wbuf)
{
	ubifs_assert(!hrtimer_active(&wbuf->timer));

	if (wbuf->no_timer)
		return;
	dbg_io("set timer for jhead %s, %llu-%llu millisecs",
	       dbg_jhead(wbuf->jhead),
	       div_u64(ktime_to_ns(wbuf->softlimit), USEC_PER_SEC),
	       div_u64(ktime_to_ns(wbuf->softlimit) + wbuf->delta,
		       USEC_PER_SEC));
	hrtimer_start_range_ns(&wbuf->timer, wbuf->softlimit, wbuf->delta,
			       HRTIMER_MODE_REL);
}
#endif

/**
 * cancel_wbuf_timer - cancel write-buffer timer.
 * @wbuf: write-buffer descriptor
 */
static void cancel_wbuf_timer_nolock(struct ubifs_wbuf *wbuf)
{
	if (wbuf->no_timer)
		return;
	wbuf->need_sync = 0;
#ifndef __UBOOT__
	hrtimer_cancel(&wbuf->timer);
#endif
}

/**
 * ubifs_wbuf_sync_nolock - synchronize write-buffer.
 * @wbuf: write-buffer to synchronize
 *
 * This function synchronizes write-buffer @buf and returns zero in case of
 * success or a negative error code in case of failure.
 *
 * Note, although write-buffers are of @c->max_write_size, this function does
 * not necessarily writes all @c->max_write_size bytes to the flash. Instead,
 * if the write-buffer is only partially filled with data, only the used part
 * of the write-buffer (aligned on @c->min_io_size boundary) is synchronized.
 * This way we waste less space.
 */
int ubifs_wbuf_sync_nolock(struct ubifs_wbuf *wbuf)
{
	struct ubifs_info *c = wbuf->c;
	int err, dirt, sync_len;

	cancel_wbuf_timer_nolock(wbuf);
	if (!wbuf->used || wbuf->lnum == -1)
		/* Write-buffer is empty or not seeked */
		return 0;

	dbg_io("LEB %d:%d, %d bytes, jhead %s",
	       wbuf->lnum, wbuf->offs, wbuf->used, dbg_jhead(wbuf->jhead));
	ubifs_assert(!(wbuf->avail & 7));
	ubifs_assert(wbuf->offs + wbuf->size <= c->leb_size);
	ubifs_assert(wbuf->size >= c->min_io_size);
	ubifs_assert(wbuf->size <= c->max_write_size);
	ubifs_assert(wbuf->size % c->min_io_size == 0);
	ubifs_assert(!c->ro_media && !c->ro_mount);
	if (c->leb_size - wbuf->offs >= c->max_write_size)
		ubifs_assert(!((wbuf->offs + wbuf->size) % c->max_write_size));

	if (c->ro_error)
		return -EROFS;

	/*
	 * Do not write whole write buffer but write only the minimum necessary
	 * amount of min. I/O units.
	 */
	sync_len = ALIGN(wbuf->used, c->min_io_size);
	dirt = sync_len - wbuf->used;
	if (dirt)
		ubifs_pad(c, wbuf->buf + wbuf->used, dirt);
	err = ubifs_leb_write(c, wbuf->lnum, wbuf->buf, wbuf->offs, sync_len);
	if (err)
		return err;

	spin_lock(&wbuf->lock);
	wbuf->offs += sync_len;
	/*
	 * Now @wbuf->offs is not necessarily aligned to @c->max_write_size.
	 * But our goal is to optimize writes and make sure we write in
	 * @c->max_write_size chunks and to @c->max_write_size-aligned offset.
	 * Thus, if @wbuf->offs is not aligned to @c->max_write_size now, make
	 * sure that @wbuf->offs + @wbuf->size is aligned to
	 * @c->max_write_size. This way we make sure that after next
	 * write-buffer flush we are again at the optimal offset (aligned to
	 * @c->max_write_size).
	 */
	if (c->leb_size - wbuf->offs < c->max_write_size)
		wbuf->size = c->leb_size - wbuf->offs;
	else if (wbuf->offs & (c->max_write_size - 1))
		wbuf->size = ALIGN(wbuf->offs, c->max_write_size) - wbuf->offs;
	else
		wbuf->size = c->max_write_size;
	wbuf->avail = wbuf->size;
	wbuf->used = 0;
	wbuf->next_ino = 0;
	spin_unlock(&wbuf->lock);

	if (wbuf->sync_callback)
		err = wbuf->sync_callback(c, wbuf->lnum,
					  c->leb_size - wbuf->offs, dirt);
	return err;
}

/**
 * ubifs_wbuf_seek_nolock - seek write-buffer.
 * @wbuf: write-buffer
 * @lnum: logical eraseblock number to seek to
 * @offs: logical eraseblock offset to seek to
 *
 * This function targets the write-buffer to logical eraseblock @lnum:@offs.
 * The write-buffer has to be empty. Returns zero in case of success and a
 * negative error code in case of failure.
 */
int ubifs_wbuf_seek_nolock(struct ubifs_wbuf *wbuf, int lnum, int offs)
{
	const struct ubifs_info *c = wbuf->c;

	dbg_io("LEB %d:%d, jhead %s", lnum, offs, dbg_jhead(wbuf->jhead));
	ubifs_assert(lnum >= 0 && lnum < c->leb_cnt);
	ubifs_assert(offs >= 0 && offs <= c->leb_size);
	ubifs_assert(offs % c->min_io_size == 0 && !(offs & 7));
	ubifs_assert(lnum != wbuf->lnum);
	ubifs_assert(wbuf->used == 0);

	spin_lock(&wbuf->lock);
	wbuf->lnum = lnum;
	wbuf->offs = offs;
	if (c->leb_size - wbuf->offs < c->max_write_size)
		wbuf->size = c->leb_size - wbuf->offs;
	else if (wbuf->offs & (c->max_write_size - 1))
		wbuf->size = ALIGN(wbuf->offs, c->max_write_size) - wbuf->offs;
	else
		wbuf->size = c->max_write_size;
	wbuf->avail = wbuf->size;
	wbuf->used = 0;
	spin_unlock(&wbuf->lock);

	return 0;
}

#ifndef __UBOOT__
/**
 * ubifs_bg_wbufs_sync - synchronize write-buffers.
 * @c: UBIFS file-system description object
 *
 * This function is called by background thread to synchronize write-buffers.
 * Returns zero in case of success and a negative error code in case of
 * failure.
 */
int ubifs_bg_wbufs_sync(struct ubifs_info *c)
{
	int err, i;

	ubifs_assert(!c->ro_media && !c->ro_mount);
	if (!c->need_wbuf_sync)
		return 0;
	c->need_wbuf_sync = 0;

	if (c->ro_error) {
		err = -EROFS;
		goto out_timers;
	}

	dbg_io("synchronize");
	for (i = 0; i < c->jhead_cnt; i++) {
		struct ubifs_wbuf *wbuf = &c->jheads[i].wbuf;

		cond_resched();

		/*
		 * If the mutex is locked then wbuf is being changed, so
		 * synchronization is not necessary.
		 */
		if (mutex_is_locked(&wbuf->io_mutex))
			continue;

		mutex_lock_nested(&wbuf->io_mutex, wbuf->jhead);
		if (!wbuf->need_sync) {
			mutex_unlock(&wbuf->io_mutex);
			continue;
		}

		err = ubifs_wbuf_sync_nolock(wbuf);
		mutex_unlock(&wbuf->io_mutex);
		if (err) {
646
			ubifs_err(c, "cannot sync write-buffer, error %d", err);
647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842
			ubifs_ro_mode(c, err);
			goto out_timers;
		}
	}

	return 0;

out_timers:
	/* Cancel all timers to prevent repeated errors */
	for (i = 0; i < c->jhead_cnt; i++) {
		struct ubifs_wbuf *wbuf = &c->jheads[i].wbuf;

		mutex_lock_nested(&wbuf->io_mutex, wbuf->jhead);
		cancel_wbuf_timer_nolock(wbuf);
		mutex_unlock(&wbuf->io_mutex);
	}
	return err;
}

/**
 * ubifs_wbuf_write_nolock - write data to flash via write-buffer.
 * @wbuf: write-buffer
 * @buf: node to write
 * @len: node length
 *
 * This function writes data to flash via write-buffer @wbuf. This means that
 * the last piece of the node won't reach the flash media immediately if it
 * does not take whole max. write unit (@c->max_write_size). Instead, the node
 * will sit in RAM until the write-buffer is synchronized (e.g., by timer, or
 * because more data are appended to the write-buffer).
 *
 * This function returns zero in case of success and a negative error code in
 * case of failure. If the node cannot be written because there is no more
 * space in this logical eraseblock, %-ENOSPC is returned.
 */
int ubifs_wbuf_write_nolock(struct ubifs_wbuf *wbuf, void *buf, int len)
{
	struct ubifs_info *c = wbuf->c;
	int err, written, n, aligned_len = ALIGN(len, 8);

	dbg_io("%d bytes (%s) to jhead %s wbuf at LEB %d:%d", len,
	       dbg_ntype(((struct ubifs_ch *)buf)->node_type),
	       dbg_jhead(wbuf->jhead), wbuf->lnum, wbuf->offs + wbuf->used);
	ubifs_assert(len > 0 && wbuf->lnum >= 0 && wbuf->lnum < c->leb_cnt);
	ubifs_assert(wbuf->offs >= 0 && wbuf->offs % c->min_io_size == 0);
	ubifs_assert(!(wbuf->offs & 7) && wbuf->offs <= c->leb_size);
	ubifs_assert(wbuf->avail > 0 && wbuf->avail <= wbuf->size);
	ubifs_assert(wbuf->size >= c->min_io_size);
	ubifs_assert(wbuf->size <= c->max_write_size);
	ubifs_assert(wbuf->size % c->min_io_size == 0);
	ubifs_assert(mutex_is_locked(&wbuf->io_mutex));
	ubifs_assert(!c->ro_media && !c->ro_mount);
	ubifs_assert(!c->space_fixup);
	if (c->leb_size - wbuf->offs >= c->max_write_size)
		ubifs_assert(!((wbuf->offs + wbuf->size) % c->max_write_size));

	if (c->leb_size - wbuf->offs - wbuf->used < aligned_len) {
		err = -ENOSPC;
		goto out;
	}

	cancel_wbuf_timer_nolock(wbuf);

	if (c->ro_error)
		return -EROFS;

	if (aligned_len <= wbuf->avail) {
		/*
		 * The node is not very large and fits entirely within
		 * write-buffer.
		 */
		memcpy(wbuf->buf + wbuf->used, buf, len);

		if (aligned_len == wbuf->avail) {
			dbg_io("flush jhead %s wbuf to LEB %d:%d",
			       dbg_jhead(wbuf->jhead), wbuf->lnum, wbuf->offs);
			err = ubifs_leb_write(c, wbuf->lnum, wbuf->buf,
					      wbuf->offs, wbuf->size);
			if (err)
				goto out;

			spin_lock(&wbuf->lock);
			wbuf->offs += wbuf->size;
			if (c->leb_size - wbuf->offs >= c->max_write_size)
				wbuf->size = c->max_write_size;
			else
				wbuf->size = c->leb_size - wbuf->offs;
			wbuf->avail = wbuf->size;
			wbuf->used = 0;
			wbuf->next_ino = 0;
			spin_unlock(&wbuf->lock);
		} else {
			spin_lock(&wbuf->lock);
			wbuf->avail -= aligned_len;
			wbuf->used += aligned_len;
			spin_unlock(&wbuf->lock);
		}

		goto exit;
	}

	written = 0;

	if (wbuf->used) {
		/*
		 * The node is large enough and does not fit entirely within
		 * current available space. We have to fill and flush
		 * write-buffer and switch to the next max. write unit.
		 */
		dbg_io("flush jhead %s wbuf to LEB %d:%d",
		       dbg_jhead(wbuf->jhead), wbuf->lnum, wbuf->offs);
		memcpy(wbuf->buf + wbuf->used, buf, wbuf->avail);
		err = ubifs_leb_write(c, wbuf->lnum, wbuf->buf, wbuf->offs,
				      wbuf->size);
		if (err)
			goto out;

		wbuf->offs += wbuf->size;
		len -= wbuf->avail;
		aligned_len -= wbuf->avail;
		written += wbuf->avail;
	} else if (wbuf->offs & (c->max_write_size - 1)) {
		/*
		 * The write-buffer offset is not aligned to
		 * @c->max_write_size and @wbuf->size is less than
		 * @c->max_write_size. Write @wbuf->size bytes to make sure the
		 * following writes are done in optimal @c->max_write_size
		 * chunks.
		 */
		dbg_io("write %d bytes to LEB %d:%d",
		       wbuf->size, wbuf->lnum, wbuf->offs);
		err = ubifs_leb_write(c, wbuf->lnum, buf, wbuf->offs,
				      wbuf->size);
		if (err)
			goto out;

		wbuf->offs += wbuf->size;
		len -= wbuf->size;
		aligned_len -= wbuf->size;
		written += wbuf->size;
	}

	/*
	 * The remaining data may take more whole max. write units, so write the
	 * remains multiple to max. write unit size directly to the flash media.
	 * We align node length to 8-byte boundary because we anyway flash wbuf
	 * if the remaining space is less than 8 bytes.
	 */
	n = aligned_len >> c->max_write_shift;
	if (n) {
		n <<= c->max_write_shift;
		dbg_io("write %d bytes to LEB %d:%d", n, wbuf->lnum,
		       wbuf->offs);
		err = ubifs_leb_write(c, wbuf->lnum, buf + written,
				      wbuf->offs, n);
		if (err)
			goto out;
		wbuf->offs += n;
		aligned_len -= n;
		len -= n;
		written += n;
	}

	spin_lock(&wbuf->lock);
	if (aligned_len)
		/*
		 * And now we have what's left and what does not take whole
		 * max. write unit, so write it to the write-buffer and we are
		 * done.
		 */
		memcpy(wbuf->buf, buf + written, len);

	if (c->leb_size - wbuf->offs >= c->max_write_size)
		wbuf->size = c->max_write_size;
	else
		wbuf->size = c->leb_size - wbuf->offs;
	wbuf->avail = wbuf->size - aligned_len;
	wbuf->used = aligned_len;
	wbuf->next_ino = 0;
	spin_unlock(&wbuf->lock);

exit:
	if (wbuf->sync_callback) {
		int free = c->leb_size - wbuf->offs - wbuf->used;

		err = wbuf->sync_callback(c, wbuf->lnum, free, 0);
		if (err)
			goto out;
	}

	if (wbuf->used)
		new_wbuf_timer_nolock(wbuf);

	return 0;

out:
843
	ubifs_err(c, "cannot write %d bytes to LEB %d:%d, error %d",
844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942
		  len, wbuf->lnum, wbuf->offs, err);
	ubifs_dump_node(c, buf);
	dump_stack();
	ubifs_dump_leb(c, wbuf->lnum);
	return err;
}

/**
 * ubifs_write_node - write node to the media.
 * @c: UBIFS file-system description object
 * @buf: the node to write
 * @len: node length
 * @lnum: logical eraseblock number
 * @offs: offset within the logical eraseblock
 *
 * This function automatically fills node magic number, assigns sequence
 * number, and calculates node CRC checksum. The length of the @buf buffer has
 * to be aligned to the minimal I/O unit size. This function automatically
 * appends padding node and padding bytes if needed. Returns zero in case of
 * success and a negative error code in case of failure.
 */
int ubifs_write_node(struct ubifs_info *c, void *buf, int len, int lnum,
		     int offs)
{
	int err, buf_len = ALIGN(len, c->min_io_size);

	dbg_io("LEB %d:%d, %s, length %d (aligned %d)",
	       lnum, offs, dbg_ntype(((struct ubifs_ch *)buf)->node_type), len,
	       buf_len);
	ubifs_assert(lnum >= 0 && lnum < c->leb_cnt && offs >= 0);
	ubifs_assert(offs % c->min_io_size == 0 && offs < c->leb_size);
	ubifs_assert(!c->ro_media && !c->ro_mount);
	ubifs_assert(!c->space_fixup);

	if (c->ro_error)
		return -EROFS;

	ubifs_prepare_node(c, buf, len, 1);
	err = ubifs_leb_write(c, lnum, buf, offs, buf_len);
	if (err)
		ubifs_dump_node(c, buf);

	return err;
}
#endif

/**
 * ubifs_read_node_wbuf - read node from the media or write-buffer.
 * @wbuf: wbuf to check for un-written data
 * @buf: buffer to read to
 * @type: node type
 * @len: node length
 * @lnum: logical eraseblock number
 * @offs: offset within the logical eraseblock
 *
 * This function reads a node of known type and length, checks it and stores
 * in @buf. If the node partially or fully sits in the write-buffer, this
 * function takes data from the buffer, otherwise it reads the flash media.
 * Returns zero in case of success, %-EUCLEAN if CRC mismatched and a negative
 * error code in case of failure.
 */
int ubifs_read_node_wbuf(struct ubifs_wbuf *wbuf, void *buf, int type, int len,
			 int lnum, int offs)
{
	const struct ubifs_info *c = wbuf->c;
	int err, rlen, overlap;
	struct ubifs_ch *ch = buf;

	dbg_io("LEB %d:%d, %s, length %d, jhead %s", lnum, offs,
	       dbg_ntype(type), len, dbg_jhead(wbuf->jhead));
	ubifs_assert(wbuf && lnum >= 0 && lnum < c->leb_cnt && offs >= 0);
	ubifs_assert(!(offs & 7) && offs < c->leb_size);
	ubifs_assert(type >= 0 && type < UBIFS_NODE_TYPES_CNT);

	spin_lock(&wbuf->lock);
	overlap = (lnum == wbuf->lnum && offs + len > wbuf->offs);
	if (!overlap) {
		/* We may safely unlock the write-buffer and read the data */
		spin_unlock(&wbuf->lock);
		return ubifs_read_node(c, buf, type, len, lnum, offs);
	}

	/* Don't read under wbuf */
	rlen = wbuf->offs - offs;
	if (rlen < 0)
		rlen = 0;

	/* Copy the rest from the write-buffer */
	memcpy(buf + rlen, wbuf->buf + offs + rlen - wbuf->offs, len - rlen);
	spin_unlock(&wbuf->lock);

	if (rlen > 0) {
		/* Read everything that goes before write-buffer */
		err = ubifs_leb_read(c, lnum, buf, offs, rlen, 0);
		if (err && err != -EBADMSG)
			return err;
	}

	if (type != ch->node_type) {
943
		ubifs_err(c, "bad node type (%d but expected %d)",
944 945 946 947 948 949
			  ch->node_type, type);
		goto out;
	}

	err = ubifs_check_node(c, buf, lnum, offs, 0, 0);
	if (err) {
950
		ubifs_err(c, "expected node type %d", type);
951 952 953 954 955
		return err;
	}

	rlen = le32_to_cpu(ch->len);
	if (rlen != len) {
956
		ubifs_err(c, "bad node length %d, expected %d", rlen, len);
957 958 959 960 961 962
		goto out;
	}

	return 0;

out:
963
	ubifs_err(c, "bad node at LEB %d:%d", lnum, offs);
964 965 966 967 968
	ubifs_dump_node(c, buf);
	dump_stack();
	return -EINVAL;
}

969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993
/**
 * ubifs_read_node - read node.
 * @c: UBIFS file-system description object
 * @buf: buffer to read to
 * @type: node type
 * @len: node length (not aligned)
 * @lnum: logical eraseblock number
 * @offs: offset within the logical eraseblock
 *
 * This function reads a node of known type and and length, checks it and
 * stores in @buf. Returns zero in case of success, %-EUCLEAN if CRC mismatched
 * and a negative error code in case of failure.
 */
int ubifs_read_node(const struct ubifs_info *c, void *buf, int type, int len,
		    int lnum, int offs)
{
	int err, l;
	struct ubifs_ch *ch = buf;

	dbg_io("LEB %d:%d, %s, length %d", lnum, offs, dbg_ntype(type), len);
	ubifs_assert(lnum >= 0 && lnum < c->leb_cnt && offs >= 0);
	ubifs_assert(len >= UBIFS_CH_SZ && offs + len <= c->leb_size);
	ubifs_assert(!(offs & 7) && offs < c->leb_size);
	ubifs_assert(type >= 0 && type < UBIFS_NODE_TYPES_CNT);

994 995
	err = ubifs_leb_read(c, lnum, buf, offs, len, 0);
	if (err && err != -EBADMSG)
996 997 998
		return err;

	if (type != ch->node_type) {
999 1000
		ubifs_errc(c, "bad node type (%d but expected %d)",
			   ch->node_type, type);
1001 1002 1003 1004 1005
		goto out;
	}

	err = ubifs_check_node(c, buf, lnum, offs, 0, 0);
	if (err) {
1006
		ubifs_errc(c, "expected node type %d", type);
1007 1008 1009 1010 1011
		return err;
	}

	l = le32_to_cpu(ch->len);
	if (l != len) {
1012
		ubifs_errc(c, "bad node length %d, expected %d", l, len);
1013 1014 1015 1016 1017 1018
		goto out;
	}

	return 0;

out:
1019 1020 1021 1022 1023 1024
	ubifs_errc(c, "bad node at LEB %d:%d, LEB mapping status %d", lnum,
		   offs, ubi_is_mapped(c->ubi, lnum));
	if (!c->probing) {
		ubifs_dump_node(c, buf);
		dump_stack();
	}
1025 1026
	return -EINVAL;
}
1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160

/**
 * ubifs_wbuf_init - initialize write-buffer.
 * @c: UBIFS file-system description object
 * @wbuf: write-buffer to initialize
 *
 * This function initializes write-buffer. Returns zero in case of success
 * %-ENOMEM in case of failure.
 */
int ubifs_wbuf_init(struct ubifs_info *c, struct ubifs_wbuf *wbuf)
{
	size_t size;

	wbuf->buf = kmalloc(c->max_write_size, GFP_KERNEL);
	if (!wbuf->buf)
		return -ENOMEM;

	size = (c->max_write_size / UBIFS_CH_SZ + 1) * sizeof(ino_t);
	wbuf->inodes = kmalloc(size, GFP_KERNEL);
	if (!wbuf->inodes) {
		kfree(wbuf->buf);
		wbuf->buf = NULL;
		return -ENOMEM;
	}

	wbuf->used = 0;
	wbuf->lnum = wbuf->offs = -1;
	/*
	 * If the LEB starts at the max. write size aligned address, then
	 * write-buffer size has to be set to @c->max_write_size. Otherwise,
	 * set it to something smaller so that it ends at the closest max.
	 * write size boundary.
	 */
	size = c->max_write_size - (c->leb_start % c->max_write_size);
	wbuf->avail = wbuf->size = size;
	wbuf->sync_callback = NULL;
	mutex_init(&wbuf->io_mutex);
	spin_lock_init(&wbuf->lock);
	wbuf->c = c;
	wbuf->next_ino = 0;

#ifndef __UBOOT__
	hrtimer_init(&wbuf->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
	wbuf->timer.function = wbuf_timer_callback_nolock;
	wbuf->softlimit = ktime_set(WBUF_TIMEOUT_SOFTLIMIT, 0);
	wbuf->delta = WBUF_TIMEOUT_HARDLIMIT - WBUF_TIMEOUT_SOFTLIMIT;
	wbuf->delta *= 1000000000ULL;
	ubifs_assert(wbuf->delta <= ULONG_MAX);
#endif
	return 0;
}

/**
 * ubifs_wbuf_add_ino_nolock - add an inode number into the wbuf inode array.
 * @wbuf: the write-buffer where to add
 * @inum: the inode number
 *
 * This function adds an inode number to the inode array of the write-buffer.
 */
void ubifs_wbuf_add_ino_nolock(struct ubifs_wbuf *wbuf, ino_t inum)
{
	if (!wbuf->buf)
		/* NOR flash or something similar */
		return;

	spin_lock(&wbuf->lock);
	if (wbuf->used)
		wbuf->inodes[wbuf->next_ino++] = inum;
	spin_unlock(&wbuf->lock);
}

/**
 * wbuf_has_ino - returns if the wbuf contains data from the inode.
 * @wbuf: the write-buffer
 * @inum: the inode number
 *
 * This function returns with %1 if the write-buffer contains some data from the
 * given inode otherwise it returns with %0.
 */
static int wbuf_has_ino(struct ubifs_wbuf *wbuf, ino_t inum)
{
	int i, ret = 0;

	spin_lock(&wbuf->lock);
	for (i = 0; i < wbuf->next_ino; i++)
		if (inum == wbuf->inodes[i]) {
			ret = 1;
			break;
		}
	spin_unlock(&wbuf->lock);

	return ret;
}

/**
 * ubifs_sync_wbufs_by_inode - synchronize write-buffers for an inode.
 * @c: UBIFS file-system description object
 * @inode: inode to synchronize
 *
 * This function synchronizes write-buffers which contain nodes belonging to
 * @inode. Returns zero in case of success and a negative error code in case of
 * failure.
 */
int ubifs_sync_wbufs_by_inode(struct ubifs_info *c, struct inode *inode)
{
	int i, err = 0;

	for (i = 0; i < c->jhead_cnt; i++) {
		struct ubifs_wbuf *wbuf = &c->jheads[i].wbuf;

		if (i == GCHD)
			/*
			 * GC head is special, do not look at it. Even if the
			 * head contains something related to this inode, it is
			 * a _copy_ of corresponding on-flash node which sits
			 * somewhere else.
			 */
			continue;

		if (!wbuf_has_ino(wbuf, inode->i_ino))
			continue;

		mutex_lock_nested(&wbuf->io_mutex, wbuf->jhead);
		if (wbuf_has_ino(wbuf, inode->i_ino))
			err = ubifs_wbuf_sync_nolock(wbuf);
		mutex_unlock(&wbuf->io_mutex);

		if (err) {
			ubifs_ro_mode(c, err);
			return err;
		}
	}
	return 0;
}