/* * 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 */