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ext4_extents.h
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ext4_extents.h
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/*
* Copyright (c) 2003-2006, Cluster File Systems, Inc, info@clusterfs.com
* Written by Alex Tomas <alex@clusterfs.com>
*
* 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 Licens
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-
*/
#ifndef _EXT4_EXTENTS
#define _EXT4_EXTENTS
#include "ext4.h"
/*
* With AGGRESSIVE_TEST defined, the capacity of index/leaf blocks
* becomes very small, so index split, in-depth growing and
* other hard changes happen much more often.
* This is for debug purposes only.
*/
#define AGGRESSIVE_TEST_
/*
* With EXTENTS_STATS defined, the number of blocks and extents
* are collected in the truncate path. They'll be shown at
* umount time.
*/
#define EXTENTS_STATS__
/*
* If CHECK_BINSEARCH is defined, then the results of the binary search
* will also be checked by linear search.
*/
#define CHECK_BINSEARCH__
/*
* If EXT_DEBUG is defined you can use the 'extdebug' mount option
* to get lots of info about what's going on.
*/
#define EXT_DEBUG__
#ifdef EXT_DEBUG
#define ext_debug(a...) printk(a)
#else
#define ext_debug(a...)
#endif
/*
* If EXT_STATS is defined then stats numbers are collected.
* These number will be displayed at umount time.
*/
#define EXT_STATS_
/*
* ext4_inode has i_block array (60 bytes total).
* The first 12 bytes store ext4_extent_header;
* the remainder stores an array of ext4_extent.
*/
/*
* This is the extent on-disk structure.
* It's used at the bottom of the tree.
*/
struct ext4_extent {
__le32 ee_block; /* first logical block extent covers */
__le16 ee_len; /* number of blocks covered by extent */
__le16 ee_start_hi; /* high 16 bits of physical block */
__le32 ee_start_lo; /* low 32 bits of physical block */
};
/*
* This is index on-disk structure.
* It's used at all the levels except the bottom.
*/
struct ext4_extent_idx {
__le32 ei_block; /* index covers logical blocks from 'block' */
__le32 ei_leaf_lo; /* pointer to the physical block of the next *
* level. leaf or next index could be there */
__le16 ei_leaf_hi; /* high 16 bits of physical block */
__u16 ei_unused;
};
/*
* Each block (leaves and indexes), even inode-stored has header.
*/
struct ext4_extent_header {
__le16 eh_magic; /* probably will support different formats */
__le16 eh_entries; /* number of valid entries */
__le16 eh_max; /* capacity of store in entries */
__le16 eh_depth; /* has tree real underlying blocks? */
__le32 eh_generation; /* generation of the tree */
};
#define EXT4_EXT_MAGIC cpu_to_le16(0xf30a)
/*
* Array of ext4_ext_path contains path to some extent.
* Creation/lookup routines use it for traversal/splitting/etc.
* Truncate uses it to simulate recursive walking.
*/
struct ext4_ext_path {
ext4_fsblk_t p_block;
__u16 p_depth;
struct ext4_extent *p_ext;
struct ext4_extent_idx *p_idx;
struct ext4_extent_header *p_hdr;
struct buffer_head *p_bh;
};
/*
* structure for external API
*/
#define EXT4_EXT_CACHE_NO 0
#define EXT4_EXT_CACHE_GAP 1
#define EXT4_EXT_CACHE_EXTENT 2
/*
* to be called by ext4_ext_walk_space()
* negative retcode - error
* positive retcode - signal for ext4_ext_walk_space(), see below
* callback must return valid extent (passed or newly created)
*/
typedef int (*ext_prepare_callback)(struct inode *, struct ext4_ext_path *,
struct ext4_ext_cache *,
struct ext4_extent *, void *);
#define EXT_CONTINUE 0
#define EXT_BREAK 1
#define EXT_REPEAT 2
#define EXT_MAX_BLOCK 0xffffffff
/*
* EXT_INIT_MAX_LEN is the maximum number of blocks we can have in an
* initialized extent. This is 2^15 and not (2^16 - 1), since we use the
* MSB of ee_len field in the extent datastructure to signify if this
* particular extent is an initialized extent or an uninitialized (i.e.
* preallocated).
* EXT_UNINIT_MAX_LEN is the maximum number of blocks we can have in an
* uninitialized extent.
* If ee_len is <= 0x8000, it is an initialized extent. Otherwise, it is an
* uninitialized one. In other words, if MSB of ee_len is set, it is an
* uninitialized extent with only one special scenario when ee_len = 0x8000.
* In this case we can not have an uninitialized extent of zero length and
* thus we make it as a special case of initialized extent with 0x8000 length.
* This way we get better extent-to-group alignment for initialized extents.
* Hence, the maximum number of blocks we can have in an *initialized*
* extent is 2^15 (32768) and in an *uninitialized* extent is 2^15-1 (32767).
*/
#define EXT_INIT_MAX_LEN (1UL << 15)
#define EXT_UNINIT_MAX_LEN (EXT_INIT_MAX_LEN - 1)
#define EXT_FIRST_EXTENT(__hdr__) \
((struct ext4_extent *) (((char *) (__hdr__)) + \
sizeof(struct ext4_extent_header)))
#define EXT_FIRST_INDEX(__hdr__) \
((struct ext4_extent_idx *) (((char *) (__hdr__)) + \
sizeof(struct ext4_extent_header)))
#define EXT_HAS_FREE_INDEX(__path__) \
(le16_to_cpu((__path__)->p_hdr->eh_entries) \
< le16_to_cpu((__path__)->p_hdr->eh_max))
#define EXT_LAST_EXTENT(__hdr__) \
(EXT_FIRST_EXTENT((__hdr__)) + le16_to_cpu((__hdr__)->eh_entries) - 1)
#define EXT_LAST_INDEX(__hdr__) \
(EXT_FIRST_INDEX((__hdr__)) + le16_to_cpu((__hdr__)->eh_entries) - 1)
#define EXT_MAX_EXTENT(__hdr__) \
(EXT_FIRST_EXTENT((__hdr__)) + le16_to_cpu((__hdr__)->eh_max) - 1)
#define EXT_MAX_INDEX(__hdr__) \
(EXT_FIRST_INDEX((__hdr__)) + le16_to_cpu((__hdr__)->eh_max) - 1)
static inline struct ext4_extent_header *ext_inode_hdr(struct inode *inode)
{
return (struct ext4_extent_header *) EXT4_I(inode)->i_data;
}
static inline struct ext4_extent_header *ext_block_hdr(struct buffer_head *bh)
{
return (struct ext4_extent_header *) bh->b_data;
}
static inline unsigned short ext_depth(struct inode *inode)
{
return le16_to_cpu(ext_inode_hdr(inode)->eh_depth);
}
static inline void ext4_ext_tree_changed(struct inode *inode)
{
EXT4_I(inode)->i_ext_generation++;
}
static inline void
ext4_ext_invalidate_cache(struct inode *inode)
{
EXT4_I(inode)->i_cached_extent.ec_type = EXT4_EXT_CACHE_NO;
}
static inline void ext4_ext_mark_uninitialized(struct ext4_extent *ext)
{
/* We can not have an uninitialized extent of zero length! */
BUG_ON((le16_to_cpu(ext->ee_len) & ~EXT_INIT_MAX_LEN) == 0);
ext->ee_len |= cpu_to_le16(EXT_INIT_MAX_LEN);
}
static inline int ext4_ext_is_uninitialized(struct ext4_extent *ext)
{
/* Extent with ee_len of 0x8000 is treated as an initialized extent */
return (le16_to_cpu(ext->ee_len) > EXT_INIT_MAX_LEN);
}
static inline int ext4_ext_get_actual_len(struct ext4_extent *ext)
{
return (le16_to_cpu(ext->ee_len) <= EXT_INIT_MAX_LEN ?
le16_to_cpu(ext->ee_len) :
(le16_to_cpu(ext->ee_len) - EXT_INIT_MAX_LEN));
}
extern int ext4_ext_calc_metadata_amount(struct inode *inode, int blocks);
extern ext4_fsblk_t idx_pblock(struct ext4_extent_idx *);
extern void ext4_ext_store_pblock(struct ext4_extent *, ext4_fsblk_t);
extern int ext4_extent_tree_init(handle_t *, struct inode *);
extern int ext4_ext_calc_credits_for_single_extent(struct inode *inode,
int num,
struct ext4_ext_path *path);
extern int ext4_ext_try_to_merge(struct inode *inode,
struct ext4_ext_path *path,
struct ext4_extent *);
extern unsigned int ext4_ext_check_overlap(struct inode *, struct ext4_extent *, struct ext4_ext_path *);
extern int ext4_ext_insert_extent(handle_t *, struct inode *, struct ext4_ext_path *, struct ext4_extent *);
extern int ext4_ext_walk_space(struct inode *, ext4_lblk_t, ext4_lblk_t,
ext_prepare_callback, void *);
extern struct ext4_ext_path *ext4_ext_find_extent(struct inode *, ext4_lblk_t,
struct ext4_ext_path *);
extern int ext4_ext_search_left(struct inode *, struct ext4_ext_path *,
ext4_lblk_t *, ext4_fsblk_t *);
extern int ext4_ext_search_right(struct inode *, struct ext4_ext_path *,
ext4_lblk_t *, ext4_fsblk_t *);
extern void ext4_ext_drop_refs(struct ext4_ext_path *);
#endif /* _EXT4_EXTENTS */