[linux-2.6-block.git] / fs / ext4 / ext4_extents.h

/*
 * 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_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.
 * For non-inode extent blocks, ext4_extent_tail
 * follows the array.
 */

/*
 * This is the extent tail on-disk structure.
 * All other extent structures are 12 bytes long.  It turns out that
 * block_size % 12 >= 4 for at least all powers of 2 greater than 512, which
 * covers all valid ext4 block sizes.  Therefore, this tail structure can be
 * crammed into the end of the block without having to rebalance the tree.
 */
struct ext4_extent_tail {
	__le32	et_checksum;	/* crc32c(uuid+inum+extent_block) */
};

/*
 * 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)

#define EXT4_EXTENT_TAIL_OFFSET(hdr) \
	(sizeof(struct ext4_extent_header) + \
	 (sizeof(struct ext4_extent) * le16_to_cpu((hdr)->eh_max)))

static inline struct ext4_extent_tail *
find_ext4_extent_tail(struct ext4_extent_header *eh)
{
	return (struct ext4_extent_tail *)(((void *)eh) +
					   EXT4_EXTENT_TAIL_OFFSET(eh));
}

/*
 * 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
 */

/*
 * Maximum number of logical blocks in a file; ext4_extent's ee_block is
 * __le32.
 */
#define EXT_MAX_BLOCKS	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_invalidate_cache(struct inode *inode)
{
	EXT4_I(inode)->i_cached_extent.ec_len = 0;
}

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));
}

static inline void ext4_ext_mark_initialized(struct ext4_extent *ext)
{
	ext->ee_len = cpu_to_le16(ext4_ext_get_actual_len(ext));
}

/*
 * ext4_ext_pblock:
 * combine low and high parts of physical block number into ext4_fsblk_t
 */
static inline ext4_fsblk_t ext4_ext_pblock(struct ext4_extent *ex)
{
	ext4_fsblk_t block;

	block = le32_to_cpu(ex->ee_start_lo);
	block |= ((ext4_fsblk_t) le16_to_cpu(ex->ee_start_hi) << 31) << 1;
	return block;
}

/*
 * ext4_idx_pblock:
 * combine low and high parts of a leaf physical block number into ext4_fsblk_t
 */
static inline ext4_fsblk_t ext4_idx_pblock(struct ext4_extent_idx *ix)
{
	ext4_fsblk_t block;

	block = le32_to_cpu(ix->ei_leaf_lo);
	block |= ((ext4_fsblk_t) le16_to_cpu(ix->ei_leaf_hi) << 31) << 1;
	return block;
}

/*
 * ext4_ext_store_pblock:
 * stores a large physical block number into an extent struct,
 * breaking it into parts
 */
static inline void ext4_ext_store_pblock(struct ext4_extent *ex,
					 ext4_fsblk_t pb)
{
	ex->ee_start_lo = cpu_to_le32((unsigned long) (pb & 0xffffffff));
	ex->ee_start_hi = cpu_to_le16((unsigned long) ((pb >> 31) >> 1) &
				      0xffff);
}

/*
 * ext4_idx_store_pblock:
 * stores a large physical block number into an index struct,
 * breaking it into parts
 */
static inline void ext4_idx_store_pblock(struct ext4_extent_idx *ix,
					 ext4_fsblk_t pb)
{
	ix->ei_leaf_lo = cpu_to_le32((unsigned long) (pb & 0xffffffff));
	ix->ei_leaf_hi = cpu_to_le16((unsigned long) ((pb >> 31) >> 1) &
				     0xffff);
}

#endif /* _EXT4_EXTENTS */
Commit	Line	Data
a86c6181 AT	1	/*
	2	* Copyright (c) 2003-2006, Cluster File Systems, Inc, info@clusterfs.com
	3	* Written by Alex Tomas <alex@clusterfs.com>
	4	*
	5	* This program is free software; you can redistribute it and/or modify
	6	* it under the terms of the GNU General Public License version 2 as
	7	* published by the Free Software Foundation.
	8	*
	9	* This program is distributed in the hope that it will be useful,
	10	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	11	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	12	* GNU General Public License for more details.
	13	*
	14	* You should have received a copy of the GNU General Public Licens
	15	* along with this program; if not, write to the Free Software
	16	* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-
	17	*/
	18
3dcf5451 CH	19	#ifndef _EXT4_EXTENTS
3dcf5451 CH	20	#define _EXT4_EXTENTS
a86c6181	21
3dcf5451	22	#include "ext4.h"
a86c6181 AT	23
a86c6181 AT	24	/*
bbf2f9fb	25	* With AGGRESSIVE_TEST defined, the capacity of index/leaf blocks
d0d856e8 RD	26	* becomes very small, so index split, in-depth growing and
	27	* other hard changes happen much more often.
	28	* This is for debug purposes only.
a86c6181	29	*/
bbf2f9fb	30	#define AGGRESSIVE_TEST_
a86c6181 AT	31
a86c6181 AT	32	/*
d0d856e8 RD	33	* With EXTENTS_STATS defined, the number of blocks and extents
	34	* are collected in the truncate path. They'll be shown at
	35	* umount time.
a86c6181 AT	36	*/
	37	#define EXTENTS_STATS__
	38
	39	/*
d0d856e8 RD	40	* If CHECK_BINSEARCH is defined, then the results of the binary search
d0d856e8 RD	41	* will also be checked by linear search.
a86c6181 AT	42	*/
	43	#define CHECK_BINSEARCH__
	44
a86c6181	45	/*
d0d856e8 RD	46	* If EXT_STATS is defined then stats numbers are collected.
d0d856e8 RD	47	* These number will be displayed at umount time.
a86c6181 AT	48	*/
	49	#define EXT_STATS_
	50
	51
	52	/*
d0d856e8 RD	53	* ext4_inode has i_block array (60 bytes total).
	54	* The first 12 bytes store ext4_extent_header;
	55	* the remainder stores an array of ext4_extent.
e6153918 DW	56	* For non-inode extent blocks, ext4_extent_tail
e6153918 DW	57	* follows the array.
a86c6181 AT	58	*/
a86c6181 AT	59
e6153918 DW	60	/*
	61	* This is the extent tail on-disk structure.
	62	* All other extent structures are 12 bytes long. It turns out that
	63	* block_size % 12 >= 4 for at least all powers of 2 greater than 512, which
	64	* covers all valid ext4 block sizes. Therefore, this tail structure can be
	65	* crammed into the end of the block without having to rebalance the tree.
	66	*/
	67	struct ext4_extent_tail {
	68	__le32 et_checksum; /* crc32c(uuid+inum+extent_block) */
	69	};
	70
a86c6181	71	/*
d0d856e8 RD	72	* This is the extent on-disk structure.
d0d856e8 RD	73	* It's used at the bottom of the tree.
a86c6181 AT	74	*/
	75	struct ext4_extent {
	76	__le32 ee_block; /* first logical block extent covers */
	77	__le16 ee_len; /* number of blocks covered by extent */
	78	__le16 ee_start_hi; /* high 16 bits of physical block */
b377611d	79	__le32 ee_start_lo; /* low 32 bits of physical block */
a86c6181 AT	80	};
	81
	82	/*
d0d856e8 RD	83	* This is index on-disk structure.
d0d856e8 RD	84	* It's used at all the levels except the bottom.
a86c6181 AT	85	*/
	86	struct ext4_extent_idx {
	87	__le32 ei_block; /* index covers logical blocks from 'block' */
d8dd0b45	88	__le32 ei_leaf_lo; /* pointer to the physical block of the next *
d0d856e8	89	* level. leaf or next index could be there */
a86c6181 AT	90	__le16 ei_leaf_hi; /* high 16 bits of physical block */
	91	__u16 ei_unused;
	92	};
	93
	94	/*
d0d856e8	95	* Each block (leaves and indexes), even inode-stored has header.
a86c6181 AT	96	*/
	97	struct ext4_extent_header {
	98	__le16 eh_magic; /* probably will support different formats */
	99	__le16 eh_entries; /* number of valid entries */
	100	__le16 eh_max; /* capacity of store in entries */
d0d856e8	101	__le16 eh_depth; /* has tree real underlying blocks? */
a86c6181 AT	102	__le32 eh_generation; /* generation of the tree */
	103	};
	104
	105	#define EXT4_EXT_MAGIC cpu_to_le16(0xf30a)
	106
7ac5990d DW	107	#define EXT4_EXTENT_TAIL_OFFSET(hdr) \
	108	(sizeof(struct ext4_extent_header) + \
	109	(sizeof(struct ext4_extent) * le16_to_cpu((hdr)->eh_max)))
	110
	111	static inline struct ext4_extent_tail *
	112	find_ext4_extent_tail(struct ext4_extent_header *eh)
	113	{
	114	return (struct ext4_extent_tail )(((void )eh) +
	115	EXT4_EXTENT_TAIL_OFFSET(eh));
	116	}
	117
a86c6181	118	/*
d0d856e8 RD	119	* Array of ext4_ext_path contains path to some extent.
	120	* Creation/lookup routines use it for traversal/splitting/etc.
	121	* Truncate uses it to simulate recursive walking.
a86c6181 AT	122	*/
a86c6181 AT	123	struct ext4_ext_path {
f65e6fba	124	ext4_fsblk_t p_block;
a86c6181 AT	125	__u16 p_depth;
	126	struct ext4_extent *p_ext;
	127	struct ext4_extent_idx *p_idx;
	128	struct ext4_extent_header *p_hdr;
	129	struct buffer_head *p_bh;
	130	};
	131
	132	/*
	133	* structure for external API
	134	*/
	135
f17722f9 LC	136	/*
	137	* Maximum number of logical blocks in a file; ext4_extent's ee_block is
	138	* __le32.
	139	*/
	140	#define EXT_MAX_BLOCKS 0xffffffff
a86c6181	141
749269fa AA	142	/*
	143	* EXT_INIT_MAX_LEN is the maximum number of blocks we can have in an
	144	* initialized extent. This is 2^15 and not (2^16 - 1), since we use the
	145	* MSB of ee_len field in the extent datastructure to signify if this
	146	* particular extent is an initialized extent or an uninitialized (i.e.
	147	* preallocated).
	148	* EXT_UNINIT_MAX_LEN is the maximum number of blocks we can have in an
	149	* uninitialized extent.
	150	* If ee_len is <= 0x8000, it is an initialized extent. Otherwise, it is an
	151	* uninitialized one. In other words, if MSB of ee_len is set, it is an
	152	* uninitialized extent with only one special scenario when ee_len = 0x8000.
	153	* In this case we can not have an uninitialized extent of zero length and
	154	* thus we make it as a special case of initialized extent with 0x8000 length.
	155	* This way we get better extent-to-group alignment for initialized extents.
	156	* Hence, the maximum number of blocks we can have in an initialized
	157	* extent is 2^15 (32768) and in an uninitialized extent is 2^15-1 (32767).
	158	*/
	159	#define EXT_INIT_MAX_LEN (1UL << 15)
	160	#define EXT_UNINIT_MAX_LEN (EXT_INIT_MAX_LEN - 1)
471d4011	161
a86c6181 AT	162
	163	#define EXT_FIRST_EXTENT(__hdr__) \
	164	((struct ext4_extent ) (((char ) (__hdr__)) + \
	165	sizeof(struct ext4_extent_header)))
	166	#define EXT_FIRST_INDEX(__hdr__) \
	167	((struct ext4_extent_idx ) (((char ) (__hdr__)) + \
	168	sizeof(struct ext4_extent_header)))
	169	#define EXT_HAS_FREE_INDEX(__path__) \
8c55e204 DK	170	(le16_to_cpu((__path__)->p_hdr->eh_entries) \
8c55e204 DK	171	< le16_to_cpu((__path__)->p_hdr->eh_max))
a86c6181 AT	172	#define EXT_LAST_EXTENT(__hdr__) \
	173	(EXT_FIRST_EXTENT((__hdr__)) + le16_to_cpu((__hdr__)->eh_entries) - 1)
	174	#define EXT_LAST_INDEX(__hdr__) \
	175	(EXT_FIRST_INDEX((__hdr__)) + le16_to_cpu((__hdr__)->eh_entries) - 1)
	176	#define EXT_MAX_EXTENT(__hdr__) \
	177	(EXT_FIRST_EXTENT((__hdr__)) + le16_to_cpu((__hdr__)->eh_max) - 1)
	178	#define EXT_MAX_INDEX(__hdr__) \
	179	(EXT_FIRST_INDEX((__hdr__)) + le16_to_cpu((__hdr__)->eh_max) - 1)
	180
	181	static inline struct ext4_extent_header ext_inode_hdr(struct inode inode)
	182	{
	183	return (struct ext4_extent_header *) EXT4_I(inode)->i_data;
	184	}
	185
	186	static inline struct ext4_extent_header ext_block_hdr(struct buffer_head bh)
	187	{
	188	return (struct ext4_extent_header *) bh->b_data;
	189	}
	190
	191	static inline unsigned short ext_depth(struct inode *inode)
	192	{
	193	return le16_to_cpu(ext_inode_hdr(inode)->eh_depth);
	194	}
	195
a86c6181 AT	196	static inline void
	197	ext4_ext_invalidate_cache(struct inode *inode)
	198	{
b05e6ae5	199	EXT4_I(inode)->i_cached_extent.ec_len = 0;
a86c6181 AT	200	}
a86c6181 AT	201
a2df2a63 AA	202	static inline void ext4_ext_mark_uninitialized(struct ext4_extent *ext)
a2df2a63 AA	203	{
749269fa AA	204	/* We can not have an uninitialized extent of zero length! */
	205	BUG_ON((le16_to_cpu(ext->ee_len) & ~EXT_INIT_MAX_LEN) == 0);
	206	ext->ee_len \|= cpu_to_le16(EXT_INIT_MAX_LEN);
a2df2a63 AA	207	}
	208
	209	static inline int ext4_ext_is_uninitialized(struct ext4_extent *ext)
	210	{
749269fa AA	211	/* Extent with ee_len of 0x8000 is treated as an initialized extent */
749269fa AA	212	return (le16_to_cpu(ext->ee_len) > EXT_INIT_MAX_LEN);
a2df2a63 AA	213	}
	214
	215	static inline int ext4_ext_get_actual_len(struct ext4_extent *ext)
	216	{
749269fa AA	217	return (le16_to_cpu(ext->ee_len) <= EXT_INIT_MAX_LEN ?
	218	le16_to_cpu(ext->ee_len) :
	219	(le16_to_cpu(ext->ee_len) - EXT_INIT_MAX_LEN));
a2df2a63 AA	220	}
a2df2a63 AA	221
0031462b MC	222	static inline void ext4_ext_mark_initialized(struct ext4_extent *ext)
	223	{
	224	ext->ee_len = cpu_to_le16(ext4_ext_get_actual_len(ext));
	225	}
	226
bf89d16f TT	227	/*
	228	* ext4_ext_pblock:
	229	* combine low and high parts of physical block number into ext4_fsblk_t
	230	*/
	231	static inline ext4_fsblk_t ext4_ext_pblock(struct ext4_extent *ex)
	232	{
	233	ext4_fsblk_t block;
	234
	235	block = le32_to_cpu(ex->ee_start_lo);
	236	block \|= ((ext4_fsblk_t) le16_to_cpu(ex->ee_start_hi) << 31) << 1;
	237	return block;
	238	}
	239
	240	/*
	241	* ext4_idx_pblock:
	242	* combine low and high parts of a leaf physical block number into ext4_fsblk_t
	243	*/
	244	static inline ext4_fsblk_t ext4_idx_pblock(struct ext4_extent_idx *ix)
	245	{
	246	ext4_fsblk_t block;
	247
	248	block = le32_to_cpu(ix->ei_leaf_lo);
	249	block \|= ((ext4_fsblk_t) le16_to_cpu(ix->ei_leaf_hi) << 31) << 1;
	250	return block;
	251	}
	252
	253	/*
	254	* ext4_ext_store_pblock:
	255	* stores a large physical block number into an extent struct,
	256	* breaking it into parts
	257	*/
	258	static inline void ext4_ext_store_pblock(struct ext4_extent *ex,
	259	ext4_fsblk_t pb)
	260	{
	261	ex->ee_start_lo = cpu_to_le32((unsigned long) (pb & 0xffffffff));
	262	ex->ee_start_hi = cpu_to_le16((unsigned long) ((pb >> 31) >> 1) &
	263	0xffff);
	264	}
	265
	266	/*
	267	* ext4_idx_store_pblock:
	268	* stores a large physical block number into an index struct,
	269	* breaking it into parts
	270	*/
	271	static inline void ext4_idx_store_pblock(struct ext4_extent_idx *ix,
	272	ext4_fsblk_t pb)
	273	{
	274	ix->ei_leaf_lo = cpu_to_le32((unsigned long) (pb & 0xffffffff));
	275	ix->ei_leaf_hi = cpu_to_le16((unsigned long) ((pb >> 31) >> 1) &
	276	0xffff);
	277	}
	278
3dcf5451	279	#endif /* _EXT4_EXTENTS */
a86c6181	280