[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 "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_bytes,
			       u64 num_bytes)
{
	int ret = 0;
	struct btrfs_file_extent_item *item;
	struct btrfs_key file_key;
	struct btrfs_path *path;
	struct extent_buffer *leaf;

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

	ret = btrfs_insert_empty_item(trans, root, path, &file_key,
				      sizeof(*item));
	if (ret < 0)
		goto out;
	BUG_ON(ret);
	leaf = path->nodes[0];
	item = btrfs_item_ptr(leaf, path->slots[0],
			      struct btrfs_file_extent_item);
	btrfs_set_file_extent_disk_bytenr(leaf, item, offset);
	btrfs_set_file_extent_disk_num_bytes(leaf, item, disk_num_bytes);
	btrfs_set_file_extent_offset(leaf, item, 0);
	btrfs_set_file_extent_num_bytes(leaf, item, num_bytes);
	btrfs_set_file_extent_generation(leaf, item, trans->transid);
	btrfs_set_file_extent_type(leaf, item, BTRFS_FILE_EXTENT_REG);
	btrfs_mark_buffer_dirty(leaf);
out:
	btrfs_free_path(path);
	return ret;
}

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 extent_buffer *leaf;
	u64 csum_offset = 0;
	int csums_in_item;

	file_key.objectid = objectid;
	file_key.offset = offset;
	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 = path->nodes[0];
	if (ret > 0) {
		ret = 1;
		if (path->slots[0] == 0)
			goto fail;
		path->slots[0]--;
		btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
		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_nr(leaf, 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;
	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,
			  struct inode *inode,
			  u64 objectid, u64 offset,
			  char *data, size_t len)
{
	int ret;
	struct btrfs_key file_key;
	struct btrfs_key found_key;
	u64 next_offset = (u64)-1;
	int found_next = 0;
	struct btrfs_path *path;
	struct btrfs_csum_item *item;
	struct extent_buffer *leaf = NULL;
	u64 csum_offset;
	u32 csum_result = ~(u32)0;
	u32 nritems;
	u32 ins_size;

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

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

	item = btrfs_lookup_csum(trans, root, path, objectid, offset, 1);
	if (!IS_ERR(item)) {
		leaf = path->nodes[0];
		goto found;
	}
	ret = PTR_ERR(item);
	if (ret == -EFBIG) {
		u32 item_size;
		/* we found one, but it isn't big enough yet */
		leaf = path->nodes[0];
		item_size = btrfs_item_size_nr(leaf, path->slots[0]);
		if ((item_size / BTRFS_CRC32_SIZE) >= MAX_CSUM_ITEMS(root)) {
			/* already at max size, make a new one */
			goto insert;
		}
	} else {
		int slot = path->slots[0] + 1;
		/* we didn't find a csum item, insert one */
		nritems = btrfs_header_nritems(path->nodes[0]);
		if (path->slots[0] >= nritems - 1) {
			ret = btrfs_next_leaf(root, path);
			if (ret == 1) {
				found_next = 1;
			} else if (ret == 0) {
				slot = 0;
			} else {
				goto insert;
			}
		}
		btrfs_item_key_to_cpu(path->nodes[0], &found_key, slot);
		if (found_key.objectid != objectid ||
		    found_key.type != BTRFS_CSUM_ITEM_KEY) {
			found_next = 1;
			goto insert;
		}
		next_offset = found_key.offset;
		found_next = 1;
		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 = path->nodes[0];
	btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
	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_nr(leaf, path->slots[0]) /
	    BTRFS_CRC32_SIZE) {
		u32 diff = (csum_offset + 1) * BTRFS_CRC32_SIZE;
		diff = diff - btrfs_item_size_nr(leaf, 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;
	if (found_next) {
		u64 tmp = min((u64)i_size_read(inode), next_offset);
		tmp -= offset + root->sectorsize - 1;
		tmp >>= root->fs_info->sb->s_blocksize_bits;
		tmp = max((u64)1, tmp);
		tmp = min(tmp, (u64)MAX_CSUM_ITEMS(root));
		ins_size = BTRFS_CRC32_SIZE * tmp;
	} else {
		ins_size = BTRFS_CRC32_SIZE;
	}
	ret = btrfs_insert_empty_item(trans, root, path, &file_key,
				      ins_size);
	if (ret < 0)
		goto fail;
	if (ret != 0) {
		WARN_ON(1);
		goto fail;
	}
csum:
	leaf = path->nodes[0];
	item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
	ret = 0;
	item = (struct btrfs_csum_item *)((unsigned char *)item +
					  csum_offset * BTRFS_CRC32_SIZE);
found:
	csum_result = btrfs_csum_data(root, data, csum_result, len);
	btrfs_csum_final(csum_result, (char *)&csum_result);
	write_extent_buffer(leaf, &csum_result, (unsigned long)item,
			    BTRFS_CRC32_SIZE);
	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 extent_buffer *leaf = path->nodes[0];
	int slot = path->slots[0];
	int ret;
	u32 new_item_size;
	u64 new_item_span;
	u64 blocks;

	btrfs_item_key_to_cpu(leaf, &key, slot);
	if (isize <= key.offset)
		return 0;
	new_item_span = isize - key.offset;
	blocks = (new_item_span + root->sectorsize - 1) >>
		root->fs_info->sb->s_blocksize_bits;
	new_item_size = blocks * BTRFS_CRC32_SIZE;
	if (new_item_size >= btrfs_item_size_nr(leaf, slot))
		return 0;
	ret = btrfs_truncate_item(trans, root, path, new_item_size);
	BUG_ON(ret);
	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
1e1d2701	19	#include "ctree.h"
dee26a9f	20	#include "disk-io.h"
9f5fae2f	21	#include "transaction.h"
1de037a4	22	#include "print-tree.h"
1e1d2701	23
6567e837	24	#define MAX_CSUM_ITEMS(r) ((((BTRFS_LEAF_DATA_SIZE(r) - \
509659cd CM	25	sizeof(struct btrfs_item) * 2) / \
509659cd CM	26	BTRFS_CRC32_SIZE) - 1))
b18c6685	27	int btrfs_insert_file_extent(struct btrfs_trans_handle *trans,
dee26a9f	28	struct btrfs_root *root,
b18c6685	29	u64 objectid, u64 pos,
db94535d CM	30	u64 offset, u64 disk_num_bytes,
db94535d CM	31	u64 num_bytes)
9f5fae2f	32	{
dee26a9f CM	33	int ret = 0;
	34	struct btrfs_file_extent_item *item;
	35	struct btrfs_key file_key;
5caf2a00	36	struct btrfs_path *path;
5f39d397	37	struct extent_buffer *leaf;
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	btrfs_set_key_type(&file_key, BTRFS_EXTENT_DATA_KEY);
dee26a9f CM	44
5caf2a00	45	ret = btrfs_insert_empty_item(trans, root, path, &file_key,
dee26a9f	46	sizeof(*item));
54aa1f4d CM	47	if (ret < 0)
54aa1f4d CM	48	goto out;
9773a788	49	BUG_ON(ret);
5f39d397 CM	50	leaf = path->nodes[0];
5f39d397 CM	51	item = btrfs_item_ptr(leaf, path->slots[0],
dee26a9f	52	struct btrfs_file_extent_item);
db94535d CM	53	btrfs_set_file_extent_disk_bytenr(leaf, item, offset);
db94535d CM	54	btrfs_set_file_extent_disk_num_bytes(leaf, item, disk_num_bytes);
5f39d397	55	btrfs_set_file_extent_offset(leaf, item, 0);
db94535d	56	btrfs_set_file_extent_num_bytes(leaf, item, num_bytes);
5f39d397 CM	57	btrfs_set_file_extent_generation(leaf, item, trans->transid);
	58	btrfs_set_file_extent_type(leaf, item, BTRFS_FILE_EXTENT_REG);
	59	btrfs_mark_buffer_dirty(leaf);
54aa1f4d	60	out:
5caf2a00	61	btrfs_free_path(path);
54aa1f4d	62	return ret;
9f5fae2f	63	}
dee26a9f	64
b18c6685 CM	65	struct btrfs_csum_item btrfs_lookup_csum(struct btrfs_trans_handle trans,
	66	struct btrfs_root *root,
	67	struct btrfs_path *path,
	68	u64 objectid, u64 offset,
	69	int cow)
6567e837 CM	70	{
	71	int ret;
	72	struct btrfs_key file_key;
	73	struct btrfs_key found_key;
	74	struct btrfs_csum_item *item;
5f39d397	75	struct extent_buffer *leaf;
6567e837	76	u64 csum_offset = 0;
a429e513	77	int csums_in_item;
6567e837 CM	78
	79	file_key.objectid = objectid;
	80	file_key.offset = offset;
6567e837	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)
6567e837 CM	84	goto fail;
5f39d397	85	leaf = path->nodes[0];
6567e837 CM	86	if (ret > 0) {
6567e837 CM	87	ret = 1;
70b2befd	88	if (path->slots[0] == 0)
6567e837 CM	89	goto fail;
6567e837 CM	90	path->slots[0]--;
5f39d397	91	btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
6567e837 CM	92	if (btrfs_key_type(&found_key) != BTRFS_CSUM_ITEM_KEY \|\|
	93	found_key.objectid != objectid) {
	94	goto fail;
	95	}
	96	csum_offset = (offset - found_key.offset) >>
	97	root->fs_info->sb->s_blocksize_bits;
5f39d397	98	csums_in_item = btrfs_item_size_nr(leaf, path->slots[0]);
509659cd	99	csums_in_item /= BTRFS_CRC32_SIZE;
a429e513 CM	100
	101	if (csum_offset >= csums_in_item) {
	102	ret = -EFBIG;
6567e837 CM	103	goto fail;
	104	}
	105	}
	106	item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
509659cd CM	107	item = (struct btrfs_csum_item )((unsigned char )item +
509659cd CM	108	csum_offset * BTRFS_CRC32_SIZE);
6567e837 CM	109	return item;
	110	fail:
	111	if (ret > 0)
b18c6685	112	ret = -ENOENT;
6567e837 CM	113	return ERR_PTR(ret);
	114	}
	115
	116
dee26a9f CM	117	int btrfs_lookup_file_extent(struct btrfs_trans_handle *trans,
	118	struct btrfs_root *root,
	119	struct btrfs_path *path, u64 objectid,
9773a788	120	u64 offset, int mod)
dee26a9f CM	121	{
	122	int ret;
	123	struct btrfs_key file_key;
	124	int ins_len = mod < 0 ? -1 : 0;
	125	int cow = mod != 0;
	126
	127	file_key.objectid = objectid;
70b2befd	128	file_key.offset = offset;
dee26a9f CM	129	btrfs_set_key_type(&file_key, BTRFS_EXTENT_DATA_KEY);
	130	ret = btrfs_search_slot(trans, root, &file_key, path, ins_len, cow);
	131	return ret;
	132	}
f254e52c CM	133
	134	int btrfs_csum_file_block(struct btrfs_trans_handle *trans,
	135	struct btrfs_root *root,
f578d4bd	136	struct inode *inode,
f254e52c CM	137	u64 objectid, u64 offset,
	138	char *data, size_t len)
	139	{
	140	int ret;
	141	struct btrfs_key file_key;
6567e837	142	struct btrfs_key found_key;
f578d4bd CM	143	u64 next_offset = (u64)-1;
f578d4bd CM	144	int found_next = 0;
5caf2a00	145	struct btrfs_path *path;
f254e52c	146	struct btrfs_csum_item *item;
ff79f819	147	struct extent_buffer *leaf = NULL;
6567e837	148	u64 csum_offset;
ff79f819	149	u32 csum_result = ~(u32)0;
f578d4bd CM	150	u32 nritems;
f578d4bd CM	151	u32 ins_size;
f254e52c	152
5caf2a00 CM	153	path = btrfs_alloc_path();
5caf2a00 CM	154	BUG_ON(!path);
b18c6685	155
f254e52c CM	156	file_key.objectid = objectid;
f254e52c CM	157	file_key.offset = offset;
f254e52c	158	btrfs_set_key_type(&file_key, BTRFS_CSUM_ITEM_KEY);
a429e513 CM	159
a429e513 CM	160	item = btrfs_lookup_csum(trans, root, path, objectid, offset, 1);
ff79f819 CM	161	if (!IS_ERR(item)) {
ff79f819 CM	162	leaf = path->nodes[0];
a429e513	163	goto found;
ff79f819	164	}
a429e513 CM	165	ret = PTR_ERR(item);
	166	if (ret == -EFBIG) {
	167	u32 item_size;
	168	/* we found one, but it isn't big enough yet */
5f39d397 CM	169	leaf = path->nodes[0];
5f39d397 CM	170	item_size = btrfs_item_size_nr(leaf, path->slots[0]);
509659cd	171	if ((item_size / BTRFS_CRC32_SIZE) >= MAX_CSUM_ITEMS(root)) {
a429e513 CM	172	/* already at max size, make a new one */
	173	goto insert;
	174	}
	175	} else {
f578d4bd	176	int slot = path->slots[0] + 1;
a429e513	177	/* we didn't find a csum item, insert one */
f578d4bd CM	178	nritems = btrfs_header_nritems(path->nodes[0]);
	179	if (path->slots[0] >= nritems - 1) {
	180	ret = btrfs_next_leaf(root, path);
	181	if (ret == 1) {
	182	found_next = 1;
	183	} else if (ret == 0) {
	184	slot = 0;
	185	} else {
	186	goto insert;
	187	}
	188	}
	189	btrfs_item_key_to_cpu(path->nodes[0], &found_key, slot);
	190	if (found_key.objectid != objectid \|\|
	191	found_key.type != BTRFS_CSUM_ITEM_KEY) {
	192	found_next = 1;
	193	goto insert;
	194	}
	195	next_offset = found_key.offset;
	196	found_next = 1;
a429e513 CM	197	goto insert;
	198	}
	199
	200	/*
	201	* at this point, we know the tree has an item, but it isn't big
	202	* enough yet to put our csum in. Grow it
	203	*/
	204	btrfs_release_path(root, path);
6567e837	205	ret = btrfs_search_slot(trans, root, &file_key, path,
509659cd	206	BTRFS_CRC32_SIZE, 1);
6567e837 CM	207	if (ret < 0)
	208	goto fail;
	209	if (ret == 0) {
b18c6685	210	BUG();
6567e837 CM	211	}
6567e837 CM	212	if (path->slots[0] == 0) {
6567e837 CM	213	goto insert;
	214	}
	215	path->slots[0]--;
5f39d397 CM	216	leaf = path->nodes[0];
5f39d397 CM	217	btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
6567e837 CM	218	csum_offset = (offset - found_key.offset) >>
	219	root->fs_info->sb->s_blocksize_bits;
	220	if (btrfs_key_type(&found_key) != BTRFS_CSUM_ITEM_KEY \|\|
	221	found_key.objectid != objectid \|\|
	222	csum_offset >= MAX_CSUM_ITEMS(root)) {
6567e837 CM	223	goto insert;
6567e837 CM	224	}
5f39d397	225	if (csum_offset >= btrfs_item_size_nr(leaf, path->slots[0]) /
509659cd CM	226	BTRFS_CRC32_SIZE) {
509659cd CM	227	u32 diff = (csum_offset + 1) * BTRFS_CRC32_SIZE;
5f39d397	228	diff = diff - btrfs_item_size_nr(leaf, path->slots[0]);
3a686375 CM	229	if (diff != BTRFS_CRC32_SIZE)
3a686375 CM	230	goto insert;
a429e513	231	ret = btrfs_extend_item(trans, root, path, diff);
6567e837 CM	232	BUG_ON(ret);
	233	goto csum;
	234	}
	235
	236	insert:
a429e513	237	btrfs_release_path(root, path);
6567e837	238	csum_offset = 0;
f578d4bd CM	239	if (found_next) {
	240	u64 tmp = min((u64)i_size_read(inode), next_offset);
	241	tmp -= offset + root->sectorsize - 1;
	242	tmp >>= root->fs_info->sb->s_blocksize_bits;
	243	tmp = max((u64)1, tmp);
	244	tmp = min(tmp, (u64)MAX_CSUM_ITEMS(root));
	245	ins_size = BTRFS_CRC32_SIZE * tmp;
	246	} else {
	247	ins_size = BTRFS_CRC32_SIZE;
	248	}
5caf2a00	249	ret = btrfs_insert_empty_item(trans, root, path, &file_key,
f578d4bd	250	ins_size);
54aa1f4d CM	251	if (ret < 0)
54aa1f4d CM	252	goto fail;
a429e513	253	if (ret != 0) {
a429e513	254	WARN_ON(1);
f254e52c	255	goto fail;
a429e513	256	}
6567e837	257	csum:
5f39d397 CM	258	leaf = path->nodes[0];
5f39d397 CM	259	item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
f254e52c	260	ret = 0;
509659cd CM	261	item = (struct btrfs_csum_item )((unsigned char )item +
509659cd CM	262	csum_offset * BTRFS_CRC32_SIZE);
b18c6685	263	found:
ff79f819 CM	264	csum_result = btrfs_csum_data(root, data, csum_result, len);
	265	btrfs_csum_final(csum_result, (char *)&csum_result);
	266	write_extent_buffer(leaf, &csum_result, (unsigned long)item,
	267	BTRFS_CRC32_SIZE);
5caf2a00	268	btrfs_mark_buffer_dirty(path->nodes[0]);
f254e52c	269	fail:
5caf2a00 CM	270	btrfs_release_path(root, path);
5caf2a00 CM	271	btrfs_free_path(path);
f254e52c CM	272	return ret;
	273	}
	274
1de037a4 CM	275	int btrfs_csum_truncate(struct btrfs_trans_handle *trans,
	276	struct btrfs_root root, struct btrfs_path path,
	277	u64 isize)
	278	{
	279	struct btrfs_key key;
5f39d397	280	struct extent_buffer *leaf = path->nodes[0];
1de037a4 CM	281	int slot = path->slots[0];
	282	int ret;
	283	u32 new_item_size;
	284	u64 new_item_span;
	285	u64 blocks;
	286
5f39d397	287	btrfs_item_key_to_cpu(leaf, &key, slot);
1de037a4 CM	288	if (isize <= key.offset)
	289	return 0;
	290	new_item_span = isize - key.offset;
5f39d397	291	blocks = (new_item_span + root->sectorsize - 1) >>
84f54cfa	292	root->fs_info->sb->s_blocksize_bits;
1de037a4	293	new_item_size = blocks * BTRFS_CRC32_SIZE;
5f39d397	294	if (new_item_size >= btrfs_item_size_nr(leaf, slot))
1de037a4 CM	295	return 0;
	296	ret = btrfs_truncate_item(trans, root, path, new_item_size);
	297	BUG_ON(ret);
	298	return ret;
	299	}
	300