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      1 // SPDX-License-Identifier: GPL-2.0+
      2 /*
      3  * This file is part of UBIFS.
      4  *
      5  * Copyright (C) 2006-2008 Nokia Corporation.
      6  * Copyright (C) 2006, 2007 University of Szeged, Hungary
      7  *
      8  * Authors: Artem Bityutskiy ( )
      9  *          Adrian Hunter
     10  *          Zoltan Sogor
     11  */
     12 
     13 /*
     14  * This file implements UBIFS I/O subsystem which provides various I/O-related
     15  * helper functions (reading/writing/checking/validating nodes) and implements
     16  * write-buffering support. Write buffers help to save space which otherwise
     17  * would have been wasted for padding to the nearest minimal I/O unit boundary.
     18  * Instead, data first goes to the write-buffer and is flushed when the
     19  * buffer is full or when it is not used for some time (by timer). This is
     20  * similar to the mechanism is used by JFFS2.
     21  *
     22  * UBIFS distinguishes between minimum write size (@c->min_io_size) and maximum
     23  * write size (@c->max_write_size). The latter is the maximum amount of bytes
     24  * the underlying flash is able to program at a time, and writing in
     25  * @c->max_write_size units should presumably be faster. Obviously,
     26  * @c->min_io_size <= @c->max_write_size. Write-buffers are of
     27  * @c->max_write_size bytes in size for maximum performance. However, when a
     28  * write-buffer is flushed, only the portion of it (aligned to @c->min_io_size
     29  * boundary) which contains data is written, not the whole write-buffer,
     30  * because this is more space-efficient.
     31  *
     32  * This optimization adds few complications to the code. Indeed, on the one
     33  * hand, we want to write in optimal @c->max_write_size bytes chunks, which
     34  * also means aligning writes at the @c->max_write_size bytes offsets. On the
     35  * other hand, we do not want to waste space when synchronizing the write
     36  * buffer, so during synchronization we writes in smaller chunks. And this makes
     37  * the next write offset to be not aligned to @c->max_write_size bytes. So the
     38  * have to make sure that the write-buffer offset (@wbuf->offs) becomes aligned
     39  * to @c->max_write_size bytes again. We do this by temporarily shrinking
     40  * write-buffer size (@wbuf->size).
     41  *
     42  * Write-buffers are defined by 'struct ubifs_wbuf' objects and protected by
     43  * mutexes defined inside these objects. Since sometimes upper-level code
     44  * has to lock the write-buffer (e.g. journal space reservation code), many
     45  * functions related to write-buffers have "nolock" suffix which means that the
     46  * caller has to lock the write-buffer before calling this function.
     47  *
     48  * UBIFS stores nodes at 64 bit-aligned addresses. If the node length is not
     49  * aligned, UBIFS starts the next node from the aligned address, and the padded
     50  * bytes may contain any rubbish. In other words, UBIFS does not put padding
     51  * bytes in those small gaps. Common headers of nodes store real node lengths,
     52  * not aligned lengths. Indexing nodes also store real lengths in branches.
     53  *
     54  * UBIFS uses padding when it pads to the next min. I/O unit. In this case it
     55  * uses padding nodes or padding bytes, if the padding node does not fit.
     56  *
     57  * All UBIFS nodes are protected by CRC checksums and UBIFS checks CRC when
     58  * they are read from the flash media.
     59  */
     60 
     61 #ifndef __UBOOT__
     62 #include <linux/crc32.h>
     63 #include <linux/slab.h>
     64 #else
     65 #include <linux/compat.h>
     66 #include <linux/err.h>
     67 #endif
     68 #include "ubifs.h"
     69 
     70 /**
     71  * ubifs_ro_mode - switch UBIFS to read read-only mode.
     72  * @c: UBIFS file-system description object
     73  * @err: error code which is the reason of switching to R/O mode
     74  */
     75 void ubifs_ro_mode(struct ubifs_info *c, int err)
     76 {
     77 	if (!c->ro_error) {
     78 		c->ro_error = 1;
     79 		c->no_chk_data_crc = 0;
     80 		c->vfs_sb->s_flags |= MS_RDONLY;
     81 		ubifs_warn(c, "switched to read-only mode, error %d", err);
     82 		dump_stack();
     83 	}
     84 }
     85 
     86 /*
     87  * Below are simple wrappers over UBI I/O functions which include some
     88  * additional checks and UBIFS debugging stuff. See corresponding UBI function
     89  * for more information.
     90  */
     91 
     92 int ubifs_leb_read(const struct ubifs_info *c, int lnum, void *buf, int offs,
     93 		   int len, int even_ebadmsg)
     94 {
     95 	int err;
     96 
     97 	err = ubi_read(c->ubi, lnum, buf, offs, len);
     98 	/*
     99 	 * In case of %-EBADMSG print the error message only if the
    100 	 * @even_ebadmsg is true.
    101 	 */
    102 	if (err && (err != -EBADMSG || even_ebadmsg)) {
    103 		ubifs_err(c, "reading %d bytes from LEB %d:%d failed, error %d",
    104 			  len, lnum, offs, err);
    105 		dump_stack();
    106 	}
    107 	return err;
    108 }
    109 
    110 int ubifs_leb_write(struct ubifs_info *c, int lnum, const void *buf, int offs,
    111 		    int len)
    112 {
    113 	int err;
    114 
    115 	ubifs_assert(!c->ro_media && !c->ro_mount);
    116 	if (c->ro_error)
    117 		return -EROFS;
    118 	if (!dbg_is_tst_rcvry(c))
    119 		err = ubi_leb_write(c->ubi, lnum, buf, offs, len);
    120 #ifndef __UBOOT__
    121 	else
    122 		err = dbg_leb_write(c, lnum, buf, offs, len);
    123 #endif
    124 	if (err) {
    125 		ubifs_err(c, "writing %d bytes to LEB %d:%d failed, error %d",
    126 			  len, lnum, offs, err);
    127 		ubifs_ro_mode(c, err);
    128 		dump_stack();
    129 	}
    130 	return err;
    131 }
    132 
    133 int ubifs_leb_change(struct ubifs_info *c, int lnum, const void *buf, int len)
    134 {
    135 	int err;
    136 
    137 	ubifs_assert(!c->ro_media && !c->ro_mount);
    138 	if (c->ro_error)
    139 		return -EROFS;
    140 	if (!dbg_is_tst_rcvry(c))
    141 		err = ubi_leb_change(c->ubi, lnum, buf, len);
    142 #ifndef __UBOOT__
    143 	else
    144 		err = dbg_leb_change(c, lnum, buf, len);
    145 #endif
    146 	if (err) {
    147 		ubifs_err(c, "changing %d bytes in LEB %d failed, error %d",
    148 			  len, lnum, err);
    149 		ubifs_ro_mode(c, err);
    150 		dump_stack();
    151 	}
    152 	return err;
    153 }
    154 
    155 int ubifs_leb_unmap(struct ubifs_info *c, int lnum)
    156 {
    157 	int err;
    158 
    159 	ubifs_assert(!c->ro_media && !c->ro_mount);
    160 	if (c->ro_error)
    161 		return -EROFS;
    162 	if (!dbg_is_tst_rcvry(c))
    163 		err = ubi_leb_unmap(c->ubi, lnum);
    164 #ifndef __UBOOT__
    165 	else
    166 		err = dbg_leb_unmap(c, lnum);
    167 #endif
    168 	if (err) {
    169 		ubifs_err(c, "unmap LEB %d failed, error %d", lnum, err);
    170 		ubifs_ro_mode(c, err);
    171 		dump_stack();
    172 	}
    173 	return err;
    174 }
    175 
    176 int ubifs_leb_map(struct ubifs_info *c, int lnum)
    177 {
    178 	int err;
    179 
    180 	ubifs_assert(!c->ro_media && !c->ro_mount);
    181 	if (c->ro_error)
    182 		return -EROFS;
    183 	if (!dbg_is_tst_rcvry(c))
    184 		err = ubi_leb_map(c->ubi, lnum);
    185 #ifndef __UBOOT__
    186 	else
    187 		err = dbg_leb_map(c, lnum);
    188 #endif
    189 	if (err) {
    190 		ubifs_err(c, "mapping LEB %d failed, error %d", lnum, err);
    191 		ubifs_ro_mode(c, err);
    192 		dump_stack();
    193 	}
    194 	return err;
    195 }
    196 
    197 int ubifs_is_mapped(const struct ubifs_info *c, int lnum)
    198 {
    199 	int err;
    200 
    201 	err = ubi_is_mapped(c->ubi, lnum);
    202 	if (err < 0) {
    203 		ubifs_err(c, "ubi_is_mapped failed for LEB %d, error %d",
    204 			  lnum, err);
    205 		dump_stack();
    206 	}
    207 	return err;
    208 }
    209 
    210 /**
    211  * ubifs_check_node - check node.
    212  * @c: UBIFS file-system description object
    213  * @buf: node to check
    214  * @lnum: logical eraseblock number
    215  * @offs: offset within the logical eraseblock
    216  * @quiet: print no messages
    217  * @must_chk_crc: indicates whether to always check the CRC
    218  *
    219  * This function checks node magic number and CRC checksum. This function also
    220  * validates node length to prevent UBIFS from becoming crazy when an attacker
    221  * feeds it a file-system image with incorrect nodes. For example, too large
    222  * node length in the common header could cause UBIFS to read memory outside of
    223  * allocated buffer when checking the CRC checksum.
    224  *
    225  * This function may skip data nodes CRC checking if @c->no_chk_data_crc is
    226  * true, which is controlled by corresponding UBIFS mount option. However, if
    227  * @must_chk_crc is true, then @c->no_chk_data_crc is ignored and CRC is
    228  * checked. Similarly, if @c->mounting or @c->remounting_rw is true (we are
    229  * mounting or re-mounting to R/W mode), @c->no_chk_data_crc is ignored and CRC
    230  * is checked. This is because during mounting or re-mounting from R/O mode to
    231  * R/W mode we may read journal nodes (when replying the journal or doing the
    232  * recovery) and the journal nodes may potentially be corrupted, so checking is
    233  * required.
    234  *
    235  * This function returns zero in case of success and %-EUCLEAN in case of bad
    236  * CRC or magic.
    237  */
    238 int ubifs_check_node(const struct ubifs_info *c, const void *buf, int lnum,
    239 		     int offs, int quiet, int must_chk_crc)
    240 {
    241 	int err = -EINVAL, type, node_len;
    242 	uint32_t crc, node_crc, magic;
    243 	const struct ubifs_ch *ch = buf;
    244 
    245 	ubifs_assert(lnum >= 0 && lnum < c->leb_cnt && offs >= 0);
    246 	ubifs_assert(!(offs & 7) && offs < c->leb_size);
    247 
    248 	magic = le32_to_cpu(ch->magic);
    249 	if (magic != UBIFS_NODE_MAGIC) {
    250 		if (!quiet)
    251 			ubifs_err(c, "bad magic %#08x, expected %#08x",
    252 				  magic, UBIFS_NODE_MAGIC);
    253 		err = -EUCLEAN;
    254 		goto out;
    255 	}
    256 
    257 	type = ch->node_type;
    258 	if (type < 0 || type >= UBIFS_NODE_TYPES_CNT) {
    259 		if (!quiet)
    260 			ubifs_err(c, "bad node type %d", type);
    261 		goto out;
    262 	}
    263 
    264 	node_len = le32_to_cpu(ch->len);
    265 	if (node_len + offs > c->leb_size)
    266 		goto out_len;
    267 
    268 	if (c->ranges[type].max_len == 0) {
    269 		if (node_len != c->ranges[type].len)
    270 			goto out_len;
    271 	} else if (node_len < c->ranges[type].min_len ||
    272 		   node_len > c->ranges[type].max_len)
    273 		goto out_len;
    274 
    275 	if (!must_chk_crc && type == UBIFS_DATA_NODE && !c->mounting &&
    276 	    !c->remounting_rw && c->no_chk_data_crc)
    277 		return 0;
    278 
    279 	crc = crc32(UBIFS_CRC32_INIT, buf + 8, node_len - 8);
    280 	node_crc = le32_to_cpu(ch->crc);
    281 	if (crc != node_crc) {
    282 		if (!quiet)
    283 			ubifs_err(c, "bad CRC: calculated %#08x, read %#08x",
    284 				  crc, node_crc);
    285 		err = -EUCLEAN;
    286 		goto out;
    287 	}
    288 
    289 	return 0;
    290 
    291 out_len:
    292 	if (!quiet)
    293 		ubifs_err(c, "bad node length %d", node_len);
    294 out:
    295 	if (!quiet) {
    296 		ubifs_err(c, "bad node at LEB %d:%d", lnum, offs);
    297 		ubifs_dump_node(c, buf);
    298 		dump_stack();
    299 	}
    300 	return err;
    301 }
    302 
    303 /**
    304  * ubifs_pad - pad flash space.
    305  * @c: UBIFS file-system description object
    306  * @buf: buffer to put padding to
    307  * @pad: how many bytes to pad
    308  *
    309  * The flash media obliges us to write only in chunks of %c->min_io_size and
    310  * when we have to write less data we add padding node to the write-buffer and
    311  * pad it to the next minimal I/O unit's boundary. Padding nodes help when the
    312  * media is being scanned. If the amount of wasted space is not enough to fit a
    313  * padding node which takes %UBIFS_PAD_NODE_SZ bytes, we write padding bytes
    314  * pattern (%UBIFS_PADDING_BYTE).
    315  *
    316  * Padding nodes are also used to fill gaps when the "commit-in-gaps" method is
    317  * used.
    318  */
    319 void ubifs_pad(const struct ubifs_info *c, void *buf, int pad)
    320 {
    321 	uint32_t crc;
    322 
    323 	ubifs_assert(pad >= 0 && !(pad & 7));
    324 
    325 	if (pad >= UBIFS_PAD_NODE_SZ) {
    326 		struct ubifs_ch *ch = buf;
    327 		struct ubifs_pad_node *pad_node = buf;
    328 
    329 		ch->magic = cpu_to_le32(UBIFS_NODE_MAGIC);
    330 		ch->node_type = UBIFS_PAD_NODE;
    331 		ch->group_type = UBIFS_NO_NODE_GROUP;
    332 		ch->padding[0] = ch->padding[1] = 0;
    333 		ch->sqnum = 0;
    334 		ch->len = cpu_to_le32(UBIFS_PAD_NODE_SZ);
    335 		pad -= UBIFS_PAD_NODE_SZ;
    336 		pad_node->pad_len = cpu_to_le32(pad);
    337 		crc = crc32(UBIFS_CRC32_INIT, buf + 8, UBIFS_PAD_NODE_SZ - 8);
    338 		ch->crc = cpu_to_le32(crc);
    339 		memset(buf + UBIFS_PAD_NODE_SZ, 0, pad);
    340 	} else if (pad > 0)
    341 		/* Too little space, padding node won't fit */
    342 		memset(buf, UBIFS_PADDING_BYTE, pad);
    343 }
    344 
    345 /**
    346  * next_sqnum - get next sequence number.
    347  * @c: UBIFS file-system description object
    348  */
    349 static unsigned long long next_sqnum(struct ubifs_info *c)
    350 {
    351 	unsigned long long sqnum;
    352 
    353 	spin_lock(&c->cnt_lock);
    354 	sqnum = ++c->max_sqnum;
    355 	spin_unlock(&c->cnt_lock);
    356 
    357 	if (unlikely(sqnum >= SQNUM_WARN_WATERMARK)) {
    358 		if (sqnum >= SQNUM_WATERMARK) {
    359 			ubifs_err(c, "sequence number overflow %llu, end of life",
    360 				  sqnum);
    361 			ubifs_ro_mode(c, -EINVAL);
    362 		}
    363 		ubifs_warn(c, "running out of sequence numbers, end of life soon");
    364 	}
    365 
    366 	return sqnum;
    367 }
    368 
    369 /**
    370  * ubifs_prepare_node - prepare node to be written to flash.
    371  * @c: UBIFS file-system description object
    372  * @node: the node to pad
    373  * @len: node length
    374  * @pad: if the buffer has to be padded
    375  *
    376  * This function prepares node at @node to be written to the media - it
    377  * calculates node CRC, fills the common header, and adds proper padding up to
    378  * the next minimum I/O unit if @pad is not zero.
    379  */
    380 void ubifs_prepare_node(struct ubifs_info *c, void *node, int len, int pad)
    381 {
    382 	uint32_t crc;
    383 	struct ubifs_ch *ch = node;
    384 	unsigned long long sqnum = next_sqnum(c);
    385 
    386 	ubifs_assert(len >= UBIFS_CH_SZ);
    387 
    388 	ch->magic = cpu_to_le32(UBIFS_NODE_MAGIC);
    389 	ch->len = cpu_to_le32(len);
    390 	ch->group_type = UBIFS_NO_NODE_GROUP;
    391 	ch->sqnum = cpu_to_le64(sqnum);
    392 	ch->padding[0] = ch->padding[1] = 0;
    393 	crc = crc32(UBIFS_CRC32_INIT, node + 8, len - 8);
    394 	ch->crc = cpu_to_le32(crc);
    395 
    396 	if (pad) {
    397 		len = ALIGN(len, 8);
    398 		pad = ALIGN(len, c->min_io_size) - len;
    399 		ubifs_pad(c, node + len, pad);
    400 	}
    401 }
    402 
    403 /**
    404  * ubifs_prep_grp_node - prepare node of a group to be written to flash.
    405  * @c: UBIFS file-system description object
    406  * @node: the node to pad
    407  * @len: node length
    408  * @last: indicates the last node of the group
    409  *
    410  * This function prepares node at @node to be written to the media - it
    411  * calculates node CRC and fills the common header.
    412  */
    413 void ubifs_prep_grp_node(struct ubifs_info *c, void *node, int len, int last)
    414 {
    415 	uint32_t crc;
    416 	struct ubifs_ch *ch = node;
    417 	unsigned long long sqnum = next_sqnum(c);
    418 
    419 	ubifs_assert(len >= UBIFS_CH_SZ);
    420 
    421 	ch->magic = cpu_to_le32(UBIFS_NODE_MAGIC);
    422 	ch->len = cpu_to_le32(len);
    423 	if (last)
    424 		ch->group_type = UBIFS_LAST_OF_NODE_GROUP;
    425 	else
    426 		ch->group_type = UBIFS_IN_NODE_GROUP;
    427 	ch->sqnum = cpu_to_le64(sqnum);
    428 	ch->padding[0] = ch->padding[1] = 0;
    429 	crc = crc32(UBIFS_CRC32_INIT, node + 8, len - 8);
    430 	ch->crc = cpu_to_le32(crc);
    431 }
    432 
    433 #ifndef __UBOOT__
    434 /**
    435  * wbuf_timer_callback - write-buffer timer callback function.
    436  * @timer: timer data (write-buffer descriptor)
    437  *
    438  * This function is called when the write-buffer timer expires.
    439  */
    440 static enum hrtimer_restart wbuf_timer_callback_nolock(struct hrtimer *timer)
    441 {
    442 	struct ubifs_wbuf *wbuf = container_of(timer, struct ubifs_wbuf, timer);
    443 
    444 	dbg_io("jhead %s", dbg_jhead(wbuf->jhead));
    445 	wbuf->need_sync = 1;
    446 	wbuf->c->need_wbuf_sync = 1;
    447 	ubifs_wake_up_bgt(wbuf->c);
    448 	return HRTIMER_NORESTART;
    449 }
    450 
    451 /**
    452  * new_wbuf_timer - start new write-buffer timer.
    453  * @wbuf: write-buffer descriptor
    454  */
    455 static void new_wbuf_timer_nolock(struct ubifs_wbuf *wbuf)
    456 {
    457 	ubifs_assert(!hrtimer_active(&wbuf->timer));
    458 
    459 	if (wbuf->no_timer)
    460 		return;
    461 	dbg_io("set timer for jhead %s, %llu-%llu millisecs",
    462 	       dbg_jhead(wbuf->jhead),
    463 	       div_u64(ktime_to_ns(wbuf->softlimit), USEC_PER_SEC),
    464 	       div_u64(ktime_to_ns(wbuf->softlimit) + wbuf->delta,
    465 		       USEC_PER_SEC));
    466 	hrtimer_start_range_ns(&wbuf->timer, wbuf->softlimit, wbuf->delta,
    467 			       HRTIMER_MODE_REL);
    468 }
    469 #endif
    470 
    471 /**
    472  * cancel_wbuf_timer - cancel write-buffer timer.
    473  * @wbuf: write-buffer descriptor
    474  */
    475 static void cancel_wbuf_timer_nolock(struct ubifs_wbuf *wbuf)
    476 {
    477 	if (wbuf->no_timer)
    478 		return;
    479 	wbuf->need_sync = 0;
    480 #ifndef __UBOOT__
    481 	hrtimer_cancel(&wbuf->timer);
    482 #endif
    483 }
    484 
    485 /**
    486  * ubifs_wbuf_sync_nolock - synchronize write-buffer.
    487  * @wbuf: write-buffer to synchronize
    488  *
    489  * This function synchronizes write-buffer @buf and returns zero in case of
    490  * success or a negative error code in case of failure.
    491  *
    492  * Note, although write-buffers are of @c->max_write_size, this function does
    493  * not necessarily writes all @c->max_write_size bytes to the flash. Instead,
    494  * if the write-buffer is only partially filled with data, only the used part
    495  * of the write-buffer (aligned on @c->min_io_size boundary) is synchronized.
    496  * This way we waste less space.
    497  */
    498 int ubifs_wbuf_sync_nolock(struct ubifs_wbuf *wbuf)
    499 {
    500 	struct ubifs_info *c = wbuf->c;
    501 	int err, dirt, sync_len;
    502 
    503 	cancel_wbuf_timer_nolock(wbuf);
    504 	if (!wbuf->used || wbuf->lnum == -1)
    505 		/* Write-buffer is empty or not seeked */
    506 		return 0;
    507 
    508 	dbg_io("LEB %d:%d, %d bytes, jhead %s",
    509 	       wbuf->lnum, wbuf->offs, wbuf->used, dbg_jhead(wbuf->jhead));
    510 	ubifs_assert(!(wbuf->avail & 7));
    511 	ubifs_assert(wbuf->offs + wbuf->size <= c->leb_size);
    512 	ubifs_assert(wbuf->size >= c->min_io_size);
    513 	ubifs_assert(wbuf->size <= c->max_write_size);
    514 	ubifs_assert(wbuf->size % c->min_io_size == 0);
    515 	ubifs_assert(!c->ro_media && !c->ro_mount);
    516 	if (c->leb_size - wbuf->offs >= c->max_write_size)
    517 		ubifs_assert(!((wbuf->offs + wbuf->size) % c->max_write_size));
    518 
    519 	if (c->ro_error)
    520 		return -EROFS;
    521 
    522 	/*
    523 	 * Do not write whole write buffer but write only the minimum necessary
    524 	 * amount of min. I/O units.
    525 	 */
    526 	sync_len = ALIGN(wbuf->used, c->min_io_size);
    527 	dirt = sync_len - wbuf->used;
    528 	if (dirt)
    529 		ubifs_pad(c, wbuf->buf + wbuf->used, dirt);
    530 	err = ubifs_leb_write(c, wbuf->lnum, wbuf->buf, wbuf->offs, sync_len);
    531 	if (err)
    532 		return err;
    533 
    534 	spin_lock(&wbuf->lock);
    535 	wbuf->offs += sync_len;
    536 	/*
    537 	 * Now @wbuf->offs is not necessarily aligned to @c->max_write_size.
    538 	 * But our goal is to optimize writes and make sure we write in
    539 	 * @c->max_write_size chunks and to @c->max_write_size-aligned offset.
    540 	 * Thus, if @wbuf->offs is not aligned to @c->max_write_size now, make
    541 	 * sure that @wbuf->offs + @wbuf->size is aligned to
    542 	 * @c->max_write_size. This way we make sure that after next
    543 	 * write-buffer flush we are again at the optimal offset (aligned to
    544 	 * @c->max_write_size).
    545 	 */
    546 	if (c->leb_size - wbuf->offs < c->max_write_size)
    547 		wbuf->size = c->leb_size - wbuf->offs;
    548 	else if (wbuf->offs & (c->max_write_size - 1))
    549 		wbuf->size = ALIGN(wbuf->offs, c->max_write_size) - wbuf->offs;
    550 	else
    551 		wbuf->size = c->max_write_size;
    552 	wbuf->avail = wbuf->size;
    553 	wbuf->used = 0;
    554 	wbuf->next_ino = 0;
    555 	spin_unlock(&wbuf->lock);
    556 
    557 	if (wbuf->sync_callback)
    558 		err = wbuf->sync_callback(c, wbuf->lnum,
    559 					  c->leb_size - wbuf->offs, dirt);
    560 	return err;
    561 }
    562 
    563 /**
    564  * ubifs_wbuf_seek_nolock - seek write-buffer.
    565  * @wbuf: write-buffer
    566  * @lnum: logical eraseblock number to seek to
    567  * @offs: logical eraseblock offset to seek to
    568  *
    569  * This function targets the write-buffer to logical eraseblock @lnum:@offs.
    570  * The write-buffer has to be empty. Returns zero in case of success and a
    571  * negative error code in case of failure.
    572  */
    573 int ubifs_wbuf_seek_nolock(struct ubifs_wbuf *wbuf, int lnum, int offs)
    574 {
    575 	const struct ubifs_info *c = wbuf->c;
    576 
    577 	dbg_io("LEB %d:%d, jhead %s", lnum, offs, dbg_jhead(wbuf->jhead));
    578 	ubifs_assert(lnum >= 0 && lnum < c->leb_cnt);
    579 	ubifs_assert(offs >= 0 && offs <= c->leb_size);
    580 	ubifs_assert(offs % c->min_io_size == 0 && !(offs & 7));
    581 	ubifs_assert(lnum != wbuf->lnum);
    582 	ubifs_assert(wbuf->used == 0);
    583 
    584 	spin_lock(&wbuf->lock);
    585 	wbuf->lnum = lnum;
    586 	wbuf->offs = offs;
    587 	if (c->leb_size - wbuf->offs < c->max_write_size)
    588 		wbuf->size = c->leb_size - wbuf->offs;
    589 	else if (wbuf->offs & (c->max_write_size - 1))
    590 		wbuf->size = ALIGN(wbuf->offs, c->max_write_size) - wbuf->offs;
    591 	else
    592 		wbuf->size = c->max_write_size;
    593 	wbuf->avail = wbuf->size;
    594 	wbuf->used = 0;
    595 	spin_unlock(&wbuf->lock);
    596 
    597 	return 0;
    598 }
    599 
    600 #ifndef __UBOOT__
    601 /**
    602  * ubifs_bg_wbufs_sync - synchronize write-buffers.
    603  * @c: UBIFS file-system description object
    604  *
    605  * This function is called by background thread to synchronize write-buffers.
    606  * Returns zero in case of success and a negative error code in case of
    607  * failure.
    608  */
    609 int ubifs_bg_wbufs_sync(struct ubifs_info *c)
    610 {
    611 	int err, i;
    612 
    613 	ubifs_assert(!c->ro_media && !c->ro_mount);
    614 	if (!c->need_wbuf_sync)
    615 		return 0;
    616 	c->need_wbuf_sync = 0;
    617 
    618 	if (c->ro_error) {
    619 		err = -EROFS;
    620 		goto out_timers;
    621 	}
    622 
    623 	dbg_io("synchronize");
    624 	for (i = 0; i < c->jhead_cnt; i++) {
    625 		struct ubifs_wbuf *wbuf = &c->jheads[i].wbuf;
    626 
    627 		cond_resched();
    628 
    629 		/*
    630 		 * If the mutex is locked then wbuf is being changed, so
    631 		 * synchronization is not necessary.
    632 		 */
    633 		if (mutex_is_locked(&wbuf->io_mutex))
    634 			continue;
    635 
    636 		mutex_lock_nested(&wbuf->io_mutex, wbuf->jhead);
    637 		if (!wbuf->need_sync) {
    638 			mutex_unlock(&wbuf->io_mutex);
    639 			continue;
    640 		}
    641 
    642 		err = ubifs_wbuf_sync_nolock(wbuf);
    643 		mutex_unlock(&wbuf->io_mutex);
    644 		if (err) {
    645 			ubifs_err(c, "cannot sync write-buffer, error %d", err);
    646 			ubifs_ro_mode(c, err);
    647 			goto out_timers;
    648 		}
    649 	}
    650 
    651 	return 0;
    652 
    653 out_timers:
    654 	/* Cancel all timers to prevent repeated errors */
    655 	for (i = 0; i < c->jhead_cnt; i++) {
    656 		struct ubifs_wbuf *wbuf = &c->jheads[i].wbuf;
    657 
    658 		mutex_lock_nested(&wbuf->io_mutex, wbuf->jhead);
    659 		cancel_wbuf_timer_nolock(wbuf);
    660 		mutex_unlock(&wbuf->io_mutex);
    661 	}
    662 	return err;
    663 }
    664 
    665 /**
    666  * ubifs_wbuf_write_nolock - write data to flash via write-buffer.
    667  * @wbuf: write-buffer
    668  * @buf: node to write
    669  * @len: node length
    670  *
    671  * This function writes data to flash via write-buffer @wbuf. This means that
    672  * the last piece of the node won't reach the flash media immediately if it
    673  * does not take whole max. write unit (@c->max_write_size). Instead, the node
    674  * will sit in RAM until the write-buffer is synchronized (e.g., by timer, or
    675  * because more data are appended to the write-buffer).
    676  *
    677  * This function returns zero in case of success and a negative error code in
    678  * case of failure. If the node cannot be written because there is no more
    679  * space in this logical eraseblock, %-ENOSPC is returned.
    680  */
    681 int ubifs_wbuf_write_nolock(struct ubifs_wbuf *wbuf, void *buf, int len)
    682 {
    683 	struct ubifs_info *c = wbuf->c;
    684 	int err, written, n, aligned_len = ALIGN(len, 8);
    685 
    686 	dbg_io("%d bytes (%s) to jhead %s wbuf at LEB %d:%d", len,
    687 	       dbg_ntype(((struct ubifs_ch *)buf)->node_type),
    688 	       dbg_jhead(wbuf->jhead), wbuf->lnum, wbuf->offs + wbuf->used);
    689 	ubifs_assert(len > 0 && wbuf->lnum >= 0 && wbuf->lnum < c->leb_cnt);
    690 	ubifs_assert(wbuf->offs >= 0 && wbuf->offs % c->min_io_size == 0);
    691 	ubifs_assert(!(wbuf->offs & 7) && wbuf->offs <= c->leb_size);
    692 	ubifs_assert(wbuf->avail > 0 && wbuf->avail <= wbuf->size);
    693 	ubifs_assert(wbuf->size >= c->min_io_size);
    694 	ubifs_assert(wbuf->size <= c->max_write_size);
    695 	ubifs_assert(wbuf->size % c->min_io_size == 0);
    696 	ubifs_assert(mutex_is_locked(&wbuf->io_mutex));
    697 	ubifs_assert(!c->ro_media && !c->ro_mount);
    698 	ubifs_assert(!c->space_fixup);
    699 	if (c->leb_size - wbuf->offs >= c->max_write_size)
    700 		ubifs_assert(!((wbuf->offs + wbuf->size) % c->max_write_size));
    701 
    702 	if (c->leb_size - wbuf->offs - wbuf->used < aligned_len) {
    703 		err = -ENOSPC;
    704 		goto out;
    705 	}
    706 
    707 	cancel_wbuf_timer_nolock(wbuf);
    708 
    709 	if (c->ro_error)
    710 		return -EROFS;
    711 
    712 	if (aligned_len <= wbuf->avail) {
    713 		/*
    714 		 * The node is not very large and fits entirely within
    715 		 * write-buffer.
    716 		 */
    717 		memcpy(wbuf->buf + wbuf->used, buf, len);
    718 
    719 		if (aligned_len == wbuf->avail) {
    720 			dbg_io("flush jhead %s wbuf to LEB %d:%d",
    721 			       dbg_jhead(wbuf->jhead), wbuf->lnum, wbuf->offs);
    722 			err = ubifs_leb_write(c, wbuf->lnum, wbuf->buf,
    723 					      wbuf->offs, wbuf->size);
    724 			if (err)
    725 				goto out;
    726 
    727 			spin_lock(&wbuf->lock);
    728 			wbuf->offs += wbuf->size;
    729 			if (c->leb_size - wbuf->offs >= c->max_write_size)
    730 				wbuf->size = c->max_write_size;
    731 			else
    732 				wbuf->size = c->leb_size - wbuf->offs;
    733 			wbuf->avail = wbuf->size;
    734 			wbuf->used = 0;
    735 			wbuf->next_ino = 0;
    736 			spin_unlock(&wbuf->lock);
    737 		} else {
    738 			spin_lock(&wbuf->lock);
    739 			wbuf->avail -= aligned_len;
    740 			wbuf->used += aligned_len;
    741 			spin_unlock(&wbuf->lock);
    742 		}
    743 
    744 		goto exit;
    745 	}
    746 
    747 	written = 0;
    748 
    749 	if (wbuf->used) {
    750 		/*
    751 		 * The node is large enough and does not fit entirely within
    752 		 * current available space. We have to fill and flush
    753 		 * write-buffer and switch to the next max. write unit.
    754 		 */
    755 		dbg_io("flush jhead %s wbuf to LEB %d:%d",
    756 		       dbg_jhead(wbuf->jhead), wbuf->lnum, wbuf->offs);
    757 		memcpy(wbuf->buf + wbuf->used, buf, wbuf->avail);
    758 		err = ubifs_leb_write(c, wbuf->lnum, wbuf->buf, wbuf->offs,
    759 				      wbuf->size);
    760 		if (err)
    761 			goto out;
    762 
    763 		wbuf->offs += wbuf->size;
    764 		len -= wbuf->avail;
    765 		aligned_len -= wbuf->avail;
    766 		written += wbuf->avail;
    767 	} else if (wbuf->offs & (c->max_write_size - 1)) {
    768 		/*
    769 		 * The write-buffer offset is not aligned to
    770 		 * @c->max_write_size and @wbuf->size is less than
    771 		 * @c->max_write_size. Write @wbuf->size bytes to make sure the
    772 		 * following writes are done in optimal @c->max_write_size
    773 		 * chunks.
    774 		 */
    775 		dbg_io("write %d bytes to LEB %d:%d",
    776 		       wbuf->size, wbuf->lnum, wbuf->offs);
    777 		err = ubifs_leb_write(c, wbuf->lnum, buf, wbuf->offs,
    778 				      wbuf->size);
    779 		if (err)
    780 			goto out;
    781 
    782 		wbuf->offs += wbuf->size;
    783 		len -= wbuf->size;
    784 		aligned_len -= wbuf->size;
    785 		written += wbuf->size;
    786 	}
    787 
    788 	/*
    789 	 * The remaining data may take more whole max. write units, so write the
    790 	 * remains multiple to max. write unit size directly to the flash media.
    791 	 * We align node length to 8-byte boundary because we anyway flash wbuf
    792 	 * if the remaining space is less than 8 bytes.
    793 	 */
    794 	n = aligned_len >> c->max_write_shift;
    795 	if (n) {
    796 		n <<= c->max_write_shift;
    797 		dbg_io("write %d bytes to LEB %d:%d", n, wbuf->lnum,
    798 		       wbuf->offs);
    799 		err = ubifs_leb_write(c, wbuf->lnum, buf + written,
    800 				      wbuf->offs, n);
    801 		if (err)
    802 			goto out;
    803 		wbuf->offs += n;
    804 		aligned_len -= n;
    805 		len -= n;
    806 		written += n;
    807 	}
    808 
    809 	spin_lock(&wbuf->lock);
    810 	if (aligned_len)
    811 		/*
    812 		 * And now we have what's left and what does not take whole
    813 		 * max. write unit, so write it to the write-buffer and we are
    814 		 * done.
    815 		 */
    816 		memcpy(wbuf->buf, buf + written, len);
    817 
    818 	if (c->leb_size - wbuf->offs >= c->max_write_size)
    819 		wbuf->size = c->max_write_size;
    820 	else
    821 		wbuf->size = c->leb_size - wbuf->offs;
    822 	wbuf->avail = wbuf->size - aligned_len;
    823 	wbuf->used = aligned_len;
    824 	wbuf->next_ino = 0;
    825 	spin_unlock(&wbuf->lock);
    826 
    827 exit:
    828 	if (wbuf->sync_callback) {
    829 		int free = c->leb_size - wbuf->offs - wbuf->used;
    830 
    831 		err = wbuf->sync_callback(c, wbuf->lnum, free, 0);
    832 		if (err)
    833 			goto out;
    834 	}
    835 
    836 	if (wbuf->used)
    837 		new_wbuf_timer_nolock(wbuf);
    838 
    839 	return 0;
    840 
    841 out:
    842 	ubifs_err(c, "cannot write %d bytes to LEB %d:%d, error %d",
    843 		  len, wbuf->lnum, wbuf->offs, err);
    844 	ubifs_dump_node(c, buf);
    845 	dump_stack();
    846 	ubifs_dump_leb(c, wbuf->lnum);
    847 	return err;
    848 }
    849 
    850 /**
    851  * ubifs_write_node - write node to the media.
    852  * @c: UBIFS file-system description object
    853  * @buf: the node to write
    854  * @len: node length
    855  * @lnum: logical eraseblock number
    856  * @offs: offset within the logical eraseblock
    857  *
    858  * This function automatically fills node magic number, assigns sequence
    859  * number, and calculates node CRC checksum. The length of the @buf buffer has
    860  * to be aligned to the minimal I/O unit size. This function automatically
    861  * appends padding node and padding bytes if needed. Returns zero in case of
    862  * success and a negative error code in case of failure.
    863  */
    864 int ubifs_write_node(struct ubifs_info *c, void *buf, int len, int lnum,
    865 		     int offs)
    866 {
    867 	int err, buf_len = ALIGN(len, c->min_io_size);
    868 
    869 	dbg_io("LEB %d:%d, %s, length %d (aligned %d)",
    870 	       lnum, offs, dbg_ntype(((struct ubifs_ch *)buf)->node_type), len,
    871 	       buf_len);
    872 	ubifs_assert(lnum >= 0 && lnum < c->leb_cnt && offs >= 0);
    873 	ubifs_assert(offs % c->min_io_size == 0 && offs < c->leb_size);
    874 	ubifs_assert(!c->ro_media && !c->ro_mount);
    875 	ubifs_assert(!c->space_fixup);
    876 
    877 	if (c->ro_error)
    878 		return -EROFS;
    879 
    880 	ubifs_prepare_node(c, buf, len, 1);
    881 	err = ubifs_leb_write(c, lnum, buf, offs, buf_len);
    882 	if (err)
    883 		ubifs_dump_node(c, buf);
    884 
    885 	return err;
    886 }
    887 #endif
    888 
    889 /**
    890  * ubifs_read_node_wbuf - read node from the media or write-buffer.
    891  * @wbuf: wbuf to check for un-written data
    892  * @buf: buffer to read to
    893  * @type: node type
    894  * @len: node length
    895  * @lnum: logical eraseblock number
    896  * @offs: offset within the logical eraseblock
    897  *
    898  * This function reads a node of known type and length, checks it and stores
    899  * in @buf. If the node partially or fully sits in the write-buffer, this
    900  * function takes data from the buffer, otherwise it reads the flash media.
    901  * Returns zero in case of success, %-EUCLEAN if CRC mismatched and a negative
    902  * error code in case of failure.
    903  */
    904 int ubifs_read_node_wbuf(struct ubifs_wbuf *wbuf, void *buf, int type, int len,
    905 			 int lnum, int offs)
    906 {
    907 	const struct ubifs_info *c = wbuf->c;
    908 	int err, rlen, overlap;
    909 	struct ubifs_ch *ch = buf;
    910 
    911 	dbg_io("LEB %d:%d, %s, length %d, jhead %s", lnum, offs,
    912 	       dbg_ntype(type), len, dbg_jhead(wbuf->jhead));
    913 	ubifs_assert(wbuf && lnum >= 0 && lnum < c->leb_cnt && offs >= 0);
    914 	ubifs_assert(!(offs & 7) && offs < c->leb_size);
    915 	ubifs_assert(type >= 0 && type < UBIFS_NODE_TYPES_CNT);
    916 
    917 	spin_lock(&wbuf->lock);
    918 	overlap = (lnum == wbuf->lnum && offs + len > wbuf->offs);
    919 	if (!overlap) {
    920 		/* We may safely unlock the write-buffer and read the data */
    921 		spin_unlock(&wbuf->lock);
    922 		return ubifs_read_node(c, buf, type, len, lnum, offs);
    923 	}
    924 
    925 	/* Don't read under wbuf */
    926 	rlen = wbuf->offs - offs;
    927 	if (rlen < 0)
    928 		rlen = 0;
    929 
    930 	/* Copy the rest from the write-buffer */
    931 	memcpy(buf + rlen, wbuf->buf + offs + rlen - wbuf->offs, len - rlen);
    932 	spin_unlock(&wbuf->lock);
    933 
    934 	if (rlen > 0) {
    935 		/* Read everything that goes before write-buffer */
    936 		err = ubifs_leb_read(c, lnum, buf, offs, rlen, 0);
    937 		if (err && err != -EBADMSG)
    938 			return err;
    939 	}
    940 
    941 	if (type != ch->node_type) {
    942 		ubifs_err(c, "bad node type (%d but expected %d)",
    943 			  ch->node_type, type);
    944 		goto out;
    945 	}
    946 
    947 	err = ubifs_check_node(c, buf, lnum, offs, 0, 0);
    948 	if (err) {
    949 		ubifs_err(c, "expected node type %d", type);
    950 		return err;
    951 	}
    952 
    953 	rlen = le32_to_cpu(ch->len);
    954 	if (rlen != len) {
    955 		ubifs_err(c, "bad node length %d, expected %d", rlen, len);
    956 		goto out;
    957 	}
    958 
    959 	return 0;
    960 
    961 out:
    962 	ubifs_err(c, "bad node at LEB %d:%d", lnum, offs);
    963 	ubifs_dump_node(c, buf);
    964 	dump_stack();
    965 	return -EINVAL;
    966 }
    967 
    968 /**
    969  * ubifs_read_node - read node.
    970  * @c: UBIFS file-system description object
    971  * @buf: buffer to read to
    972  * @type: node type
    973  * @len: node length (not aligned)
    974  * @lnum: logical eraseblock number
    975  * @offs: offset within the logical eraseblock
    976  *
    977  * This function reads a node of known type and and length, checks it and
    978  * stores in @buf. Returns zero in case of success, %-EUCLEAN if CRC mismatched
    979  * and a negative error code in case of failure.
    980  */
    981 int ubifs_read_node(const struct ubifs_info *c, void *buf, int type, int len,
    982 		    int lnum, int offs)
    983 {
    984 	int err, l;
    985 	struct ubifs_ch *ch = buf;
    986 
    987 	dbg_io("LEB %d:%d, %s, length %d", lnum, offs, dbg_ntype(type), len);
    988 	ubifs_assert(lnum >= 0 && lnum < c->leb_cnt && offs >= 0);
    989 	ubifs_assert(len >= UBIFS_CH_SZ && offs + len <= c->leb_size);
    990 	ubifs_assert(!(offs & 7) && offs < c->leb_size);
    991 	ubifs_assert(type >= 0 && type < UBIFS_NODE_TYPES_CNT);
    992 
    993 	err = ubifs_leb_read(c, lnum, buf, offs, len, 0);
    994 	if (err && err != -EBADMSG)
    995 		return err;
    996 
    997 	if (type != ch->node_type) {
    998 		ubifs_errc(c, "bad node type (%d but expected %d)",
    999 			   ch->node_type, type);
   1000 		goto out;
   1001 	}
   1002 
   1003 	err = ubifs_check_node(c, buf, lnum, offs, 0, 0);
   1004 	if (err) {
   1005 		ubifs_errc(c, "expected node type %d", type);
   1006 		return err;
   1007 	}
   1008 
   1009 	l = le32_to_cpu(ch->len);
   1010 	if (l != len) {
   1011 		ubifs_errc(c, "bad node length %d, expected %d", l, len);
   1012 		goto out;
   1013 	}
   1014 
   1015 	return 0;
   1016 
   1017 out:
   1018 	ubifs_errc(c, "bad node at LEB %d:%d, LEB mapping status %d", lnum,
   1019 		   offs, ubi_is_mapped(c->ubi, lnum));
   1020 	if (!c->probing) {
   1021 		ubifs_dump_node(c, buf);
   1022 		dump_stack();
   1023 	}
   1024 	return -EINVAL;
   1025 }
   1026 
   1027 /**
   1028  * ubifs_wbuf_init - initialize write-buffer.
   1029  * @c: UBIFS file-system description object
   1030  * @wbuf: write-buffer to initialize
   1031  *
   1032  * This function initializes write-buffer. Returns zero in case of success
   1033  * %-ENOMEM in case of failure.
   1034  */
   1035 int ubifs_wbuf_init(struct ubifs_info *c, struct ubifs_wbuf *wbuf)
   1036 {
   1037 	size_t size;
   1038 
   1039 	wbuf->buf = kmalloc(c->max_write_size, GFP_KERNEL);
   1040 	if (!wbuf->buf)
   1041 		return -ENOMEM;
   1042 
   1043 	size = (c->max_write_size / UBIFS_CH_SZ + 1) * sizeof(ino_t);
   1044 	wbuf->inodes = kmalloc(size, GFP_KERNEL);
   1045 	if (!wbuf->inodes) {
   1046 		kfree(wbuf->buf);
   1047 		wbuf->buf = NULL;
   1048 		return -ENOMEM;
   1049 	}
   1050 
   1051 	wbuf->used = 0;
   1052 	wbuf->lnum = wbuf->offs = -1;
   1053 	/*
   1054 	 * If the LEB starts at the max. write size aligned address, then
   1055 	 * write-buffer size has to be set to @c->max_write_size. Otherwise,
   1056 	 * set it to something smaller so that it ends at the closest max.
   1057 	 * write size boundary.
   1058 	 */
   1059 	size = c->max_write_size - (c->leb_start % c->max_write_size);
   1060 	wbuf->avail = wbuf->size = size;
   1061 	wbuf->sync_callback = NULL;
   1062 	mutex_init(&wbuf->io_mutex);
   1063 	spin_lock_init(&wbuf->lock);
   1064 	wbuf->c = c;
   1065 	wbuf->next_ino = 0;
   1066 
   1067 #ifndef __UBOOT__
   1068 	hrtimer_init(&wbuf->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
   1069 	wbuf->timer.function = wbuf_timer_callback_nolock;
   1070 	wbuf->softlimit = ktime_set(WBUF_TIMEOUT_SOFTLIMIT, 0);
   1071 	wbuf->delta = WBUF_TIMEOUT_HARDLIMIT - WBUF_TIMEOUT_SOFTLIMIT;
   1072 	wbuf->delta *= 1000000000ULL;
   1073 	ubifs_assert(wbuf->delta <= ULONG_MAX);
   1074 #endif
   1075 	return 0;
   1076 }
   1077 
   1078 /**
   1079  * ubifs_wbuf_add_ino_nolock - add an inode number into the wbuf inode array.
   1080  * @wbuf: the write-buffer where to add
   1081  * @inum: the inode number
   1082  *
   1083  * This function adds an inode number to the inode array of the write-buffer.
   1084  */
   1085 void ubifs_wbuf_add_ino_nolock(struct ubifs_wbuf *wbuf, ino_t inum)
   1086 {
   1087 	if (!wbuf->buf)
   1088 		/* NOR flash or something similar */
   1089 		return;
   1090 
   1091 	spin_lock(&wbuf->lock);
   1092 	if (wbuf->used)
   1093 		wbuf->inodes[wbuf->next_ino++] = inum;
   1094 	spin_unlock(&wbuf->lock);
   1095 }
   1096 
   1097 /**
   1098  * wbuf_has_ino - returns if the wbuf contains data from the inode.
   1099  * @wbuf: the write-buffer
   1100  * @inum: the inode number
   1101  *
   1102  * This function returns with %1 if the write-buffer contains some data from the
   1103  * given inode otherwise it returns with %0.
   1104  */
   1105 static int wbuf_has_ino(struct ubifs_wbuf *wbuf, ino_t inum)
   1106 {
   1107 	int i, ret = 0;
   1108 
   1109 	spin_lock(&wbuf->lock);
   1110 	for (i = 0; i < wbuf->next_ino; i++)
   1111 		if (inum == wbuf->inodes[i]) {
   1112 			ret = 1;
   1113 			break;
   1114 		}
   1115 	spin_unlock(&wbuf->lock);
   1116 
   1117 	return ret;
   1118 }
   1119 
   1120 /**
   1121  * ubifs_sync_wbufs_by_inode - synchronize write-buffers for an inode.
   1122  * @c: UBIFS file-system description object
   1123  * @inode: inode to synchronize
   1124  *
   1125  * This function synchronizes write-buffers which contain nodes belonging to
   1126  * @inode. Returns zero in case of success and a negative error code in case of
   1127  * failure.
   1128  */
   1129 int ubifs_sync_wbufs_by_inode(struct ubifs_info *c, struct inode *inode)
   1130 {
   1131 	int i, err = 0;
   1132 
   1133 	for (i = 0; i < c->jhead_cnt; i++) {
   1134 		struct ubifs_wbuf *wbuf = &c->jheads[i].wbuf;
   1135 
   1136 		if (i == GCHD)
   1137 			/*
   1138 			 * GC head is special, do not look at it. Even if the
   1139 			 * head contains something related to this inode, it is
   1140 			 * a _copy_ of corresponding on-flash node which sits
   1141 			 * somewhere else.
   1142 			 */
   1143 			continue;
   1144 
   1145 		if (!wbuf_has_ino(wbuf, inode->i_ino))
   1146 			continue;
   1147 
   1148 		mutex_lock_nested(&wbuf->io_mutex, wbuf->jhead);
   1149 		if (wbuf_has_ino(wbuf, inode->i_ino))
   1150 			err = ubifs_wbuf_sync_nolock(wbuf);
   1151 		mutex_unlock(&wbuf->io_mutex);
   1152 
   1153 		if (err) {
   1154 			ubifs_ro_mode(c, err);
   1155 			return err;
   1156 		}
   1157 	}
   1158 	return 0;
   1159 }
   1160