linux/fs/ocfs2/extent_map.h
Sunil Mushran 93862d5e1a ocfs2: Implement llseek()
ocfs2 implements its own llseek() to provide the SEEK_HOLE/SEEK_DATA
functionality.

SEEK_HOLE sets the file pointer to the start of either a hole or an unwritten
(preallocated) extent, that is greater than or equal to the supplied offset.

SEEK_DATA sets the file pointer to the start of an allocated extent (not
unwritten) that is greater than or equal to the supplied offset.

If the supplied offset is on a desired region, then the file pointer is set
to it. Offsets greater than or equal to the file size return -ENXIO.

Unwritten (preallocated) extents are considered holes because the file system
treats reads to such regions in the same way as it does to holes.

Signed-off-by: Sunil Mushran <sunil.mushran@oracle.com>
2011-07-25 14:58:15 -07:00

93 lines
2.8 KiB
C

/* -*- mode: c; c-basic-offset: 8; -*-
* vim: noexpandtab sw=8 ts=8 sts=0:
*
* extent_map.h
*
* In-memory file extent mappings for OCFS2.
*
* Copyright (C) 2004 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, version 2, 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.
*/
#ifndef _EXTENT_MAP_H
#define _EXTENT_MAP_H
struct ocfs2_extent_map_item {
unsigned int ei_cpos;
unsigned int ei_phys;
unsigned int ei_clusters;
unsigned int ei_flags;
struct list_head ei_list;
};
#define OCFS2_MAX_EXTENT_MAP_ITEMS 3
struct ocfs2_extent_map {
unsigned int em_num_items;
struct list_head em_list;
};
void ocfs2_extent_map_init(struct inode *inode);
void ocfs2_extent_map_trunc(struct inode *inode, unsigned int cluster);
void ocfs2_extent_map_insert_rec(struct inode *inode,
struct ocfs2_extent_rec *rec);
int ocfs2_get_clusters(struct inode *inode, u32 v_cluster, u32 *p_cluster,
u32 *num_clusters, unsigned int *extent_flags);
int ocfs2_extent_map_get_blocks(struct inode *inode, u64 v_blkno, u64 *p_blkno,
u64 *ret_count, unsigned int *extent_flags);
int ocfs2_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
u64 map_start, u64 map_len);
int ocfs2_seek_data_hole_offset(struct file *file, loff_t *offset, int origin);
int ocfs2_xattr_get_clusters(struct inode *inode, u32 v_cluster,
u32 *p_cluster, u32 *num_clusters,
struct ocfs2_extent_list *el,
unsigned int *extent_flags);
int ocfs2_read_virt_blocks(struct inode *inode, u64 v_block, int nr,
struct buffer_head *bhs[], int flags,
int (*validate)(struct super_block *sb,
struct buffer_head *bh));
int ocfs2_figure_hole_clusters(struct ocfs2_caching_info *ci,
struct ocfs2_extent_list *el,
struct buffer_head *eb_bh,
u32 v_cluster,
u32 *num_clusters);
static inline int ocfs2_read_virt_block(struct inode *inode, u64 v_block,
struct buffer_head **bh,
int (*validate)(struct super_block *sb,
struct buffer_head *bh))
{
int status = 0;
if (bh == NULL) {
printk("ocfs2: bh == NULL\n");
status = -EINVAL;
goto bail;
}
status = ocfs2_read_virt_blocks(inode, v_block, 1, bh, 0, validate);
bail:
return status;
}
#endif /* _EXTENT_MAP_H */