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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 _LINUX_EXT4_EXTENTS

#define _LINUX_EXT4_EXTENTS

#include <linux/ext4_fs.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 *,

                                        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_extent_tree_init(handle_t *, struct inode *);

extern int ext4_ext_calc_credits_for_insert(struct inode *, struct ext4_ext_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 *, unsigned long, unsigned long, ext_prepare_callback, void *);

extern struct ext4_ext_path * ext4_ext_find_extent(struct inode *, int, struct ext4_ext_path *);

#endif /* _LINUX_EXT4_EXTENTS */