[mirror_ubuntu-artful-kernel.git] / fs / btrfs / file-item.c

/*
 * Copyright (C) 2007 Oracle.  All rights reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public
 * License v2 as published by the Free Software Foundation.
 *
 * 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 021110-1307, USA.
 */

#include <linux/module.h>
#include "ctree.h"
#include "disk-io.h"
#include "transaction.h"
#include "print-tree.h"

#define MAX_CSUM_ITEMS(r) ((((BTRFS_LEAF_DATA_SIZE(r) - \
			       sizeof(struct btrfs_item) * 2) / \
			       BTRFS_CRC32_SIZE) - 1))
int btrfs_insert_file_extent(struct btrfs_trans_handle *trans,
			       struct btrfs_root *root,
			       u64 objectid, u64 pos,
			       u64 offset, u64 disk_num_blocks,
			       u64 num_blocks)
{
	int ret = 0;
	struct btrfs_file_extent_item *item;
	struct btrfs_key file_key;
	struct btrfs_path *path;

	path = btrfs_alloc_path();
	BUG_ON(!path);
	file_key.objectid = objectid;
	file_key.offset = pos;
	file_key.flags = 0;
	btrfs_set_key_type(&file_key, BTRFS_EXTENT_DATA_KEY);

	ret = btrfs_insert_empty_item(trans, root, path, &file_key,
				      sizeof(*item));
	BUG_ON(ret);
	item = btrfs_item_ptr(btrfs_buffer_leaf(path->nodes[0]), path->slots[0],
			      struct btrfs_file_extent_item);
	btrfs_set_file_extent_disk_blocknr(item, offset);
	btrfs_set_file_extent_disk_num_blocks(item, disk_num_blocks);
	btrfs_set_file_extent_offset(item, 0);
	btrfs_set_file_extent_num_blocks(item, num_blocks);
	btrfs_set_file_extent_generation(item, trans->transid);
	btrfs_set_file_extent_type(item, BTRFS_FILE_EXTENT_REG);
	btrfs_mark_buffer_dirty(path->nodes[0]);

	btrfs_release_path(root, path);
	btrfs_free_path(path);
	return 0;
}

struct btrfs_csum_item *btrfs_lookup_csum(struct btrfs_trans_handle *trans,
					  struct btrfs_root *root,
					  struct btrfs_path *path,
					  u64 objectid, u64 offset,
					  int cow)
{
	int ret;
	struct btrfs_key file_key;
	struct btrfs_key found_key;
	struct btrfs_csum_item *item;
	struct btrfs_leaf *leaf;
	u64 csum_offset = 0;
	int csums_in_item;

	file_key.objectid = objectid;
	file_key.offset = offset;
	file_key.flags = 0;
	btrfs_set_key_type(&file_key, BTRFS_CSUM_ITEM_KEY);
	ret = btrfs_search_slot(trans, root, &file_key, path, 0, cow);
	if (ret < 0)
		goto fail;
	leaf = btrfs_buffer_leaf(path->nodes[0]);
	if (ret > 0) {
		ret = 1;
		if (path->slots[0] == 0)
			goto fail;
		path->slots[0]--;
		btrfs_disk_key_to_cpu(&found_key,
				      &leaf->items[path->slots[0]].key);
		if (btrfs_key_type(&found_key) != BTRFS_CSUM_ITEM_KEY ||
		    found_key.objectid != objectid) {
			goto fail;
		}
		csum_offset = (offset - found_key.offset) >>
				root->fs_info->sb->s_blocksize_bits;
		csums_in_item = btrfs_item_size(leaf->items + path->slots[0]);
		csums_in_item /= BTRFS_CRC32_SIZE;

		if (csum_offset >= csums_in_item) {
			ret = -EFBIG;
			goto fail;
		}
	}
	item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
	item = (struct btrfs_csum_item *)((unsigned char *)item +
					  csum_offset * BTRFS_CRC32_SIZE);
	return item;
fail:
	if (ret > 0)
		ret = -ENOENT;
	return ERR_PTR(ret);
}


int btrfs_lookup_file_extent(struct btrfs_trans_handle *trans,
			     struct btrfs_root *root,
			     struct btrfs_path *path, u64 objectid,
			     u64 offset, int mod)
{
	int ret;
	struct btrfs_key file_key;
	int ins_len = mod < 0 ? -1 : 0;
	int cow = mod != 0;

	file_key.objectid = objectid;
	file_key.offset = offset;
	file_key.flags = 0;
	btrfs_set_key_type(&file_key, BTRFS_EXTENT_DATA_KEY);
	ret = btrfs_search_slot(trans, root, &file_key, path, ins_len, cow);
	return ret;
}

int btrfs_csum_file_block(struct btrfs_trans_handle *trans,
			  struct btrfs_root *root,
			  u64 objectid, u64 offset,
			  char *data, size_t len)
{
	int ret;
	struct btrfs_key file_key;
	struct btrfs_key found_key;
	struct btrfs_path *path;
	struct btrfs_csum_item *item;
	struct btrfs_leaf *leaf;
	u64 csum_offset;

	path = btrfs_alloc_path();
	BUG_ON(!path);

	file_key.objectid = objectid;
	file_key.offset = offset;
	file_key.flags = 0;
	btrfs_set_key_type(&file_key, BTRFS_CSUM_ITEM_KEY);

	item = btrfs_lookup_csum(trans, root, path, objectid, offset, 1);
	if (!IS_ERR(item))
		goto found;
	ret = PTR_ERR(item);
	if (ret == -EFBIG) {
		u32 item_size;
		/* we found one, but it isn't big enough yet */
		leaf = btrfs_buffer_leaf(path->nodes[0]);
		item_size = btrfs_item_size(leaf->items + path->slots[0]);
		if ((item_size / BTRFS_CRC32_SIZE) >= MAX_CSUM_ITEMS(root)) {
			/* already at max size, make a new one */
			goto insert;
		}
	} else {
		/* we didn't find a csum item, insert one */
		goto insert;
	}

	/*
	 * at this point, we know the tree has an item, but it isn't big
	 * enough yet to put our csum in.  Grow it
	 */
	btrfs_release_path(root, path);
	ret = btrfs_search_slot(trans, root, &file_key, path,
				BTRFS_CRC32_SIZE, 1);
	if (ret < 0)
		goto fail;
	if (ret == 0) {
		BUG();
	}
	if (path->slots[0] == 0) {
		goto insert;
	}
	path->slots[0]--;
	leaf = btrfs_buffer_leaf(path->nodes[0]);
	btrfs_disk_key_to_cpu(&found_key, &leaf->items[path->slots[0]].key);
	csum_offset = (offset - found_key.offset) >>
			root->fs_info->sb->s_blocksize_bits;
	if (btrfs_key_type(&found_key) != BTRFS_CSUM_ITEM_KEY ||
	    found_key.objectid != objectid ||
	    csum_offset >= MAX_CSUM_ITEMS(root)) {
		goto insert;
	}
	if (csum_offset >= btrfs_item_size(leaf->items + path->slots[0]) /
	    BTRFS_CRC32_SIZE) {
		u32 diff = (csum_offset + 1) * BTRFS_CRC32_SIZE;
		diff = diff - btrfs_item_size(leaf->items + path->slots[0]);
		if (diff != BTRFS_CRC32_SIZE)
			goto insert;
		ret = btrfs_extend_item(trans, root, path, diff);
		BUG_ON(ret);
		goto csum;
	}

insert:
	btrfs_release_path(root, path);
	csum_offset = 0;
	ret = btrfs_insert_empty_item(trans, root, path, &file_key,
				      BTRFS_CRC32_SIZE);
	if (ret != 0) {
		WARN_ON(1);
		goto fail;
	}
csum:
	item = btrfs_item_ptr(btrfs_buffer_leaf(path->nodes[0]), path->slots[0],
			      struct btrfs_csum_item);
	ret = 0;
	item = (struct btrfs_csum_item *)((unsigned char *)item +
					  csum_offset * BTRFS_CRC32_SIZE);
found:
	btrfs_check_bounds(&item->csum, BTRFS_CRC32_SIZE,
			   path->nodes[0]->b_data,
			   root->fs_info->sb->s_blocksize);
	ret = btrfs_csum_data(root, data, len, &item->csum);
	btrfs_mark_buffer_dirty(path->nodes[0]);
fail:
	btrfs_release_path(root, path);
	btrfs_free_path(path);
	return ret;
}

int btrfs_csum_truncate(struct btrfs_trans_handle *trans,
			struct btrfs_root *root, struct btrfs_path *path,
			u64 isize)
{
	struct btrfs_key key;
	struct btrfs_leaf *leaf = btrfs_buffer_leaf(path->nodes[0]);
	int slot = path->slots[0];
	int ret;
	u32 new_item_size;
	u64 new_item_span;
	u64 blocks;

	btrfs_disk_key_to_cpu(&key, &leaf->items[slot].key);
	if (isize <= key.offset)
		return 0;
	new_item_span = isize - key.offset;
	blocks = (new_item_span + root->blocksize - 1) >>
		root->fs_info->sb->s_blocksize_bits;
	new_item_size = blocks * BTRFS_CRC32_SIZE;
	if (new_item_size >= btrfs_item_size(leaf->items + slot))
		return 0;
	ret = btrfs_truncate_item(trans, root, path, new_item_size);
	BUG_ON(ret);
	return ret;
}

int btrfs_csum_verify_file_block(struct btrfs_root *root,
				 u64 objectid, u64 offset,
				 char *data, size_t len)
{
	int ret;
	struct btrfs_key file_key;
	struct btrfs_path *path;
	struct btrfs_csum_item *item;
	char result[BTRFS_CRC32_SIZE];

	path = btrfs_alloc_path();
	BUG_ON(!path);
	file_key.objectid = objectid;
	file_key.offset = offset;
	file_key.flags = 0;
	btrfs_set_key_type(&file_key, BTRFS_CSUM_ITEM_KEY);
	mutex_lock(&root->fs_info->fs_mutex);

	item = btrfs_lookup_csum(NULL, root, path, objectid, offset, 0);
	if (IS_ERR(item)) {
		ret = PTR_ERR(item);
		/* a csum that isn't present is a preallocated region. */
		if (ret == -ENOENT || ret == -EFBIG)
			ret = -ENOENT;
		goto fail;
	}

	ret = btrfs_csum_data(root, data, len, result);
	WARN_ON(ret);
	if (memcmp(result, &item->csum, BTRFS_CRC32_SIZE))
		ret = 1;
fail:
	btrfs_release_path(root, path);
	btrfs_free_path(path);
	mutex_unlock(&root->fs_info->fs_mutex);
	return ret;
}
Commit	Line	Data
6cbd5570 CM	1	/*
	2	* Copyright (C) 2007 Oracle. All rights reserved.
	3	*
	4	* This program is free software; you can redistribute it and/or
	5	* modify it under the terms of the GNU General Public
	6	* License v2 as published by the Free Software Foundation.
	7	*
	8	* This program is distributed in the hope that it will be useful,
	9	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	10	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	11	* General Public License for more details.
	12	*
	13	* You should have received a copy of the GNU General Public
	14	* License along with this program; if not, write to the
	15	* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
	16	* Boston, MA 021110-1307, USA.
	17	*/
	18
2e635a27	19	#include <linux/module.h>
1e1d2701	20	#include "ctree.h"
dee26a9f	21	#include "disk-io.h"
9f5fae2f	22	#include "transaction.h"
1de037a4	23	#include "print-tree.h"
1e1d2701	24
6567e837	25	#define MAX_CSUM_ITEMS(r) ((((BTRFS_LEAF_DATA_SIZE(r) - \
509659cd CM	26	sizeof(struct btrfs_item) * 2) / \
509659cd CM	27	BTRFS_CRC32_SIZE) - 1))
b18c6685	28	int btrfs_insert_file_extent(struct btrfs_trans_handle *trans,
dee26a9f	29	struct btrfs_root *root,
b18c6685	30	u64 objectid, u64 pos,
3a686375 CM	31	u64 offset, u64 disk_num_blocks,
3a686375 CM	32	u64 num_blocks)
9f5fae2f	33	{
dee26a9f CM	34	int ret = 0;
	35	struct btrfs_file_extent_item *item;
	36	struct btrfs_key file_key;
5caf2a00	37	struct btrfs_path *path;
dee26a9f	38
5caf2a00 CM	39	path = btrfs_alloc_path();
5caf2a00 CM	40	BUG_ON(!path);
dee26a9f	41	file_key.objectid = objectid;
b18c6685	42	file_key.offset = pos;
dee26a9f CM	43	file_key.flags = 0;
	44	btrfs_set_key_type(&file_key, BTRFS_EXTENT_DATA_KEY);
	45
5caf2a00	46	ret = btrfs_insert_empty_item(trans, root, path, &file_key,
dee26a9f	47	sizeof(*item));
9773a788	48	BUG_ON(ret);
5caf2a00	49	item = btrfs_item_ptr(btrfs_buffer_leaf(path->nodes[0]), path->slots[0],
dee26a9f	50	struct btrfs_file_extent_item);
b18c6685	51	btrfs_set_file_extent_disk_blocknr(item, offset);
3a686375	52	btrfs_set_file_extent_disk_num_blocks(item, disk_num_blocks);
dee26a9f	53	btrfs_set_file_extent_offset(item, 0);
b18c6685	54	btrfs_set_file_extent_num_blocks(item, num_blocks);
71951f35	55	btrfs_set_file_extent_generation(item, trans->transid);
236454df	56	btrfs_set_file_extent_type(item, BTRFS_FILE_EXTENT_REG);
5caf2a00	57	btrfs_mark_buffer_dirty(path->nodes[0]);
a429e513	58
5caf2a00 CM	59	btrfs_release_path(root, path);
5caf2a00 CM	60	btrfs_free_path(path);
9f5fae2f CM	61	return 0;
9f5fae2f CM	62	}
dee26a9f	63
b18c6685 CM	64	struct btrfs_csum_item btrfs_lookup_csum(struct btrfs_trans_handle trans,
	65	struct btrfs_root *root,
	66	struct btrfs_path *path,
	67	u64 objectid, u64 offset,
	68	int cow)
6567e837 CM	69	{
	70	int ret;
	71	struct btrfs_key file_key;
	72	struct btrfs_key found_key;
	73	struct btrfs_csum_item *item;
	74	struct btrfs_leaf *leaf;
	75	u64 csum_offset = 0;
a429e513	76	int csums_in_item;
6567e837 CM	77
	78	file_key.objectid = objectid;
	79	file_key.offset = offset;
	80	file_key.flags = 0;
	81	btrfs_set_key_type(&file_key, BTRFS_CSUM_ITEM_KEY);
b18c6685	82	ret = btrfs_search_slot(trans, root, &file_key, path, 0, cow);
6567e837 CM	83	if (ret < 0)
	84	goto fail;
	85	leaf = btrfs_buffer_leaf(path->nodes[0]);
	86	if (ret > 0) {
	87	ret = 1;
70b2befd	88	if (path->slots[0] == 0)
6567e837 CM	89	goto fail;
	90	path->slots[0]--;
	91	btrfs_disk_key_to_cpu(&found_key,
	92	&leaf->items[path->slots[0]].key);
	93	if (btrfs_key_type(&found_key) != BTRFS_CSUM_ITEM_KEY \|\|
	94	found_key.objectid != objectid) {
	95	goto fail;
	96	}
	97	csum_offset = (offset - found_key.offset) >>
	98	root->fs_info->sb->s_blocksize_bits;
a429e513	99	csums_in_item = btrfs_item_size(leaf->items + path->slots[0]);
509659cd	100	csums_in_item /= BTRFS_CRC32_SIZE;
a429e513 CM	101
	102	if (csum_offset >= csums_in_item) {
	103	ret = -EFBIG;
6567e837 CM	104	goto fail;
	105	}
	106	}
	107	item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
509659cd CM	108	item = (struct btrfs_csum_item )((unsigned char )item +
509659cd CM	109	csum_offset * BTRFS_CRC32_SIZE);
6567e837 CM	110	return item;
	111	fail:
	112	if (ret > 0)
b18c6685	113	ret = -ENOENT;
6567e837 CM	114	return ERR_PTR(ret);
	115	}
	116
	117
dee26a9f CM	118	int btrfs_lookup_file_extent(struct btrfs_trans_handle *trans,
	119	struct btrfs_root *root,
	120	struct btrfs_path *path, u64 objectid,
9773a788	121	u64 offset, int mod)
dee26a9f CM	122	{
	123	int ret;
	124	struct btrfs_key file_key;
	125	int ins_len = mod < 0 ? -1 : 0;
	126	int cow = mod != 0;
	127
	128	file_key.objectid = objectid;
70b2befd	129	file_key.offset = offset;
dee26a9f CM	130	file_key.flags = 0;
	131	btrfs_set_key_type(&file_key, BTRFS_EXTENT_DATA_KEY);
	132	ret = btrfs_search_slot(trans, root, &file_key, path, ins_len, cow);
	133	return ret;
	134	}
f254e52c CM	135
	136	int btrfs_csum_file_block(struct btrfs_trans_handle *trans,
	137	struct btrfs_root *root,
	138	u64 objectid, u64 offset,
	139	char *data, size_t len)
	140	{
	141	int ret;
	142	struct btrfs_key file_key;
6567e837	143	struct btrfs_key found_key;
5caf2a00	144	struct btrfs_path *path;
f254e52c	145	struct btrfs_csum_item *item;
6567e837 CM	146	struct btrfs_leaf *leaf;
6567e837 CM	147	u64 csum_offset;
f254e52c	148
5caf2a00 CM	149	path = btrfs_alloc_path();
5caf2a00 CM	150	BUG_ON(!path);
b18c6685	151
f254e52c CM	152	file_key.objectid = objectid;
	153	file_key.offset = offset;
	154	file_key.flags = 0;
	155	btrfs_set_key_type(&file_key, BTRFS_CSUM_ITEM_KEY);
a429e513 CM	156
	157	item = btrfs_lookup_csum(trans, root, path, objectid, offset, 1);
	158	if (!IS_ERR(item))
	159	goto found;
	160	ret = PTR_ERR(item);
	161	if (ret == -EFBIG) {
	162	u32 item_size;
	163	/* we found one, but it isn't big enough yet */
	164	leaf = btrfs_buffer_leaf(path->nodes[0]);
	165	item_size = btrfs_item_size(leaf->items + path->slots[0]);
509659cd	166	if ((item_size / BTRFS_CRC32_SIZE) >= MAX_CSUM_ITEMS(root)) {
a429e513 CM	167	/* already at max size, make a new one */
	168	goto insert;
	169	}
	170	} else {
	171	/* we didn't find a csum item, insert one */
	172	goto insert;
	173	}
	174
	175	/*
	176	* at this point, we know the tree has an item, but it isn't big
	177	* enough yet to put our csum in. Grow it
	178	*/
	179	btrfs_release_path(root, path);
6567e837	180	ret = btrfs_search_slot(trans, root, &file_key, path,
509659cd	181	BTRFS_CRC32_SIZE, 1);
6567e837 CM	182	if (ret < 0)
	183	goto fail;
	184	if (ret == 0) {
b18c6685	185	BUG();
6567e837 CM	186	}
6567e837 CM	187	if (path->slots[0] == 0) {
6567e837 CM	188	goto insert;
	189	}
	190	path->slots[0]--;
	191	leaf = btrfs_buffer_leaf(path->nodes[0]);
	192	btrfs_disk_key_to_cpu(&found_key, &leaf->items[path->slots[0]].key);
	193	csum_offset = (offset - found_key.offset) >>
	194	root->fs_info->sb->s_blocksize_bits;
	195	if (btrfs_key_type(&found_key) != BTRFS_CSUM_ITEM_KEY \|\|
	196	found_key.objectid != objectid \|\|
	197	csum_offset >= MAX_CSUM_ITEMS(root)) {
6567e837 CM	198	goto insert;
	199	}
	200	if (csum_offset >= btrfs_item_size(leaf->items + path->slots[0]) /
509659cd CM	201	BTRFS_CRC32_SIZE) {
509659cd CM	202	u32 diff = (csum_offset + 1) * BTRFS_CRC32_SIZE;
a429e513	203	diff = diff - btrfs_item_size(leaf->items + path->slots[0]);
3a686375 CM	204	if (diff != BTRFS_CRC32_SIZE)
3a686375 CM	205	goto insert;
a429e513	206	ret = btrfs_extend_item(trans, root, path, diff);
6567e837 CM	207	BUG_ON(ret);
	208	goto csum;
	209	}
	210
	211	insert:
a429e513	212	btrfs_release_path(root, path);
6567e837	213	csum_offset = 0;
5caf2a00	214	ret = btrfs_insert_empty_item(trans, root, path, &file_key,
509659cd	215	BTRFS_CRC32_SIZE);
a429e513	216	if (ret != 0) {
a429e513	217	WARN_ON(1);
f254e52c	218	goto fail;
a429e513	219	}
6567e837	220	csum:
5caf2a00	221	item = btrfs_item_ptr(btrfs_buffer_leaf(path->nodes[0]), path->slots[0],
f254e52c CM	222	struct btrfs_csum_item);
f254e52c CM	223	ret = 0;
509659cd CM	224	item = (struct btrfs_csum_item )((unsigned char )item +
509659cd CM	225	csum_offset * BTRFS_CRC32_SIZE);
b18c6685	226	found:
509659cd CM	227	btrfs_check_bounds(&item->csum, BTRFS_CRC32_SIZE,
	228	path->nodes[0]->b_data,
	229	root->fs_info->sb->s_blocksize);
	230	ret = btrfs_csum_data(root, data, len, &item->csum);
5caf2a00	231	btrfs_mark_buffer_dirty(path->nodes[0]);
f254e52c	232	fail:
5caf2a00 CM	233	btrfs_release_path(root, path);
5caf2a00 CM	234	btrfs_free_path(path);
f254e52c CM	235	return ret;
	236	}
	237
1de037a4 CM	238	int btrfs_csum_truncate(struct btrfs_trans_handle *trans,
	239	struct btrfs_root root, struct btrfs_path path,
	240	u64 isize)
	241	{
	242	struct btrfs_key key;
	243	struct btrfs_leaf *leaf = btrfs_buffer_leaf(path->nodes[0]);
	244	int slot = path->slots[0];
	245	int ret;
	246	u32 new_item_size;
	247	u64 new_item_span;
	248	u64 blocks;
	249
	250	btrfs_disk_key_to_cpu(&key, &leaf->items[slot].key);
	251	if (isize <= key.offset)
	252	return 0;
	253	new_item_span = isize - key.offset;
84f54cfa CM	254	blocks = (new_item_span + root->blocksize - 1) >>
84f54cfa CM	255	root->fs_info->sb->s_blocksize_bits;
1de037a4 CM	256	new_item_size = blocks * BTRFS_CRC32_SIZE;
	257	if (new_item_size >= btrfs_item_size(leaf->items + slot))
	258	return 0;
	259	ret = btrfs_truncate_item(trans, root, path, new_item_size);
	260	BUG_ON(ret);
	261	return ret;
	262	}
	263
f254e52c CM	264	int btrfs_csum_verify_file_block(struct btrfs_root *root,
	265	u64 objectid, u64 offset,
	266	char *data, size_t len)
	267	{
	268	int ret;
	269	struct btrfs_key file_key;
5caf2a00	270	struct btrfs_path *path;
f254e52c	271	struct btrfs_csum_item *item;
509659cd	272	char result[BTRFS_CRC32_SIZE];
f254e52c	273
5caf2a00 CM	274	path = btrfs_alloc_path();
5caf2a00 CM	275	BUG_ON(!path);
f254e52c CM	276	file_key.objectid = objectid;
	277	file_key.offset = offset;
	278	file_key.flags = 0;
	279	btrfs_set_key_type(&file_key, BTRFS_CSUM_ITEM_KEY);
2da566ed	280	mutex_lock(&root->fs_info->fs_mutex);
6567e837	281
b18c6685	282	item = btrfs_lookup_csum(NULL, root, path, objectid, offset, 0);
6567e837 CM	283	if (IS_ERR(item)) {
6567e837 CM	284	ret = PTR_ERR(item);
a429e513 CM	285	/* a csum that isn't present is a preallocated region. */
a429e513 CM	286	if (ret == -ENOENT \|\| ret == -EFBIG)
3a686375	287	ret = -ENOENT;
f254e52c	288	goto fail;
6567e837 CM	289	}
6567e837 CM	290
f254e52c CM	291	ret = btrfs_csum_data(root, data, len, result);
f254e52c CM	292	WARN_ON(ret);
509659cd	293	if (memcmp(result, &item->csum, BTRFS_CRC32_SIZE))
f254e52c CM	294	ret = 1;
f254e52c CM	295	fail:
5caf2a00 CM	296	btrfs_release_path(root, path);
5caf2a00 CM	297	btrfs_free_path(path);
2da566ed	298	mutex_unlock(&root->fs_info->fs_mutex);
f254e52c CM	299	return ret;
f254e52c CM	300	}