forked from kdave/btrfs-progs
/
file.c
162 lines (150 loc) · 3.95 KB
/
file.c
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/*
* Copyright (C) 2014 Fujitsu. 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 <sys/stat.h>
#include "ctree.h"
#include "transaction.h"
#include "kerncompat.h"
/*
* Get the first file extent that covers (part of) the given range
* Unlike kernel using extent_map to handle hole even no-hole is enabled,
* progs don't have such infrastructure, so caller should do extra care
* for no-hole.
*
* return 0 for found, and path points to the file extent.
* return >0 for not found, and path points to the insert position.
* return <0 for error.
*/
int btrfs_get_extent(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
struct btrfs_path *path,
u64 ino, u64 offset, u64 len, int ins_len)
{
struct btrfs_key key;
struct btrfs_key found_key;
struct btrfs_file_extent_item *fi_item;
u64 end = 0;
int ret = 0;
int not_found = 1;
key.objectid = ino;
key.type = BTRFS_EXTENT_DATA_KEY;
key.offset = offset;
ret = btrfs_search_slot(trans, root, &key, path, ins_len,
ins_len ? 1 : 0);
if (ret <= 0)
goto out;
if (ret > 0) {
/* Check preivous file extent */
ret = btrfs_previous_item(root, path, ino,
BTRFS_EXTENT_DATA_KEY);
if (ret < 0)
goto out;
if (ret > 0)
goto check_next;
}
btrfs_item_key_to_cpu(path->nodes[0], &found_key, path->slots[0]);
if (found_key.objectid != ino ||
found_key.type != BTRFS_EXTENT_DATA_KEY)
goto check_next;
fi_item = btrfs_item_ptr(path->nodes[0], path->slots[0],
struct btrfs_file_extent_item);
end = found_key.offset +
btrfs_file_extent_ram_bytes(path->nodes[0], fi_item);
/*
* existing file extent
* |--------| |----|
* |-------|
* offset + len
* OR
* |---------------|
* |-------|
*/
if (end > offset) {
not_found = 0;
goto out;
}
check_next:
ret = btrfs_next_item(root, path);
if (ret)
goto out;
btrfs_item_key_to_cpu(path->nodes[0], &found_key, path->slots[0]);
if (found_key.objectid != ino ||
found_key.type != BTRFS_EXTENT_DATA_KEY) {
ret = 1;
goto out;
}
if (found_key.offset < offset + len)
/*
* existing file extent
* |---| |------|
* |-------|
* offset + len
*/
not_found = 0;
else
/*
* existing file extent
* |----| |----|
* |----|
* offset + len
*/
not_found = 1;
/*
* To keep the search hehavior consistent with search_slot(),
* we need to go back to the prev leaf's nritem slot if
* we are at the first slot of the leaf.
*/
if (path->slots[0] == 0) {
ret = btrfs_prev_leaf(root, path);
/* Not possible */
if (ret)
goto out;
path->slots[0] = btrfs_header_nritems(path->nodes[0]);
}
out:
if (ret == 0)
ret = not_found;
return ret;
}
/*
* Punch hole ranged [offset,len) for the file given by ino and root.
*
* Unlink kernel punch_hole, which will not zero/free existing extent,
* instead it will return -EEXIST if there is any extents in the hole
* range.
*/
int btrfs_punch_hole(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
u64 ino, u64 offset, u64 len)
{
struct btrfs_path *path;
int ret = 0;
path = btrfs_alloc_path();
if (!path)
return -ENOMEM;
ret = btrfs_get_extent(NULL, root, path, ino, offset, len, 0);
if (ret < 0)
goto out;
if (ret == 0) {
ret = -EEXIST;
goto out;
}
ret = btrfs_insert_file_extent(trans, root, ino, offset, 0, 0, len);
out:
btrfs_free_path(path);
return ret;
}