- 根目录:
- 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;
__u16 p_maxdepth;
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
*/
/*
* 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 unwritten (i.e.
* preallocated).
* EXT_UNWRITTEN_MAX_LEN is the maximum number of blocks we can have in an
* unwritten extent.
* If ee_len is <= 0x8000, it is an initialized extent. Otherwise, it is an
* unwritten one. In other words, if MSB of ee_len is set, it is an
* unwritten extent with only one special scenario when ee_len = 0x8000.
* In this case we can not have an unwritten 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 *unwritten* extent is 2^15-1 (32767).
*/
#define EXT_INIT_MAX_LEN (1UL << 15)
#define EXT_UNWRITTEN_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_mark_unwritten(struct ext4_extent *ext)
{
/* We can not have an unwritten 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_unwritten(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);
}
#define ext4_ext_dirty(handle, inode, path) \
__ext4_ext_dirty(__func__, __LINE__, (handle), (inode), (path))
int __ext4_ext_dirty(const char *where, unsigned int line, handle_t *handle,
struct inode *inode, struct ext4_ext_path *path);
#endif /* _EXT4_EXTENTS */