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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>
93 lines
2.8 KiB
C
93 lines
2.8 KiB
C
/* -*- mode: c; c-basic-offset: 8; -*-
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* vim: noexpandtab sw=8 ts=8 sts=0:
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*
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* extent_map.h
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*
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* In-memory file extent mappings for OCFS2.
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*
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* Copyright (C) 2004 Oracle. All rights reserved.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public
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* License, version 2, as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public
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* License along with this program; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 021110-1307, USA.
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*/
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#ifndef _EXTENT_MAP_H
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#define _EXTENT_MAP_H
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struct ocfs2_extent_map_item {
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unsigned int ei_cpos;
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unsigned int ei_phys;
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unsigned int ei_clusters;
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unsigned int ei_flags;
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struct list_head ei_list;
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};
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#define OCFS2_MAX_EXTENT_MAP_ITEMS 3
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struct ocfs2_extent_map {
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unsigned int em_num_items;
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struct list_head em_list;
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};
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void ocfs2_extent_map_init(struct inode *inode);
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void ocfs2_extent_map_trunc(struct inode *inode, unsigned int cluster);
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void ocfs2_extent_map_insert_rec(struct inode *inode,
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struct ocfs2_extent_rec *rec);
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int ocfs2_get_clusters(struct inode *inode, u32 v_cluster, u32 *p_cluster,
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u32 *num_clusters, unsigned int *extent_flags);
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int ocfs2_extent_map_get_blocks(struct inode *inode, u64 v_blkno, u64 *p_blkno,
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u64 *ret_count, unsigned int *extent_flags);
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int ocfs2_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
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u64 map_start, u64 map_len);
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int ocfs2_seek_data_hole_offset(struct file *file, loff_t *offset, int origin);
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int ocfs2_xattr_get_clusters(struct inode *inode, u32 v_cluster,
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u32 *p_cluster, u32 *num_clusters,
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struct ocfs2_extent_list *el,
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unsigned int *extent_flags);
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int ocfs2_read_virt_blocks(struct inode *inode, u64 v_block, int nr,
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struct buffer_head *bhs[], int flags,
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int (*validate)(struct super_block *sb,
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struct buffer_head *bh));
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int ocfs2_figure_hole_clusters(struct ocfs2_caching_info *ci,
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struct ocfs2_extent_list *el,
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struct buffer_head *eb_bh,
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u32 v_cluster,
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u32 *num_clusters);
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static inline int ocfs2_read_virt_block(struct inode *inode, u64 v_block,
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struct buffer_head **bh,
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int (*validate)(struct super_block *sb,
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struct buffer_head *bh))
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{
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int status = 0;
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if (bh == NULL) {
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printk("ocfs2: bh == NULL\n");
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status = -EINVAL;
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goto bail;
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}
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status = ocfs2_read_virt_blocks(inode, v_block, 1, bh, 0, validate);
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bail:
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return status;
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}
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#endif /* _EXTENT_MAP_H */
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