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![Zheng Liu](/assets/img/avatar_default.png)
After tracking all extent status, we already have a extent cache in memory. Every time we want to lookup a block mapping, we can first try to lookup it in extent status tree to avoid a potential disk I/O. A new function called ext4_es_lookup_extent is defined to finish this work. When we try to lookup a block mapping, we always call ext4_map_blocks and/or ext4_da_map_blocks. So in these functions we first try to lookup a block mapping in extent status tree. A new flag EXT4_GET_BLOCKS_NO_PUT_HOLE is used in ext4_da_map_blocks in order not to put a hole into extent status tree because this hole will be converted to delayed extent in the tree immediately. Signed-off-by: Zheng Liu <wenqing.lz@taobao.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> Cc: Jan kara <jack@suse.cz>
109 lines
2.9 KiB
C
109 lines
2.9 KiB
C
/*
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* fs/ext4/extents_status.h
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*
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* Written by Yongqiang Yang <xiaoqiangnk@gmail.com>
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* Modified by
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* Allison Henderson <achender@linux.vnet.ibm.com>
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* Zheng Liu <wenqing.lz@taobao.com>
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*
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*/
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#ifndef _EXT4_EXTENTS_STATUS_H
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#define _EXT4_EXTENTS_STATUS_H
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/*
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* Turn on ES_DEBUG__ to get lots of info about extent status operations.
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*/
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#ifdef ES_DEBUG__
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#define es_debug(fmt, ...) printk(fmt, ##__VA_ARGS__)
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#else
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#define es_debug(fmt, ...) no_printk(fmt, ##__VA_ARGS__)
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#endif
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#define EXTENT_STATUS_WRITTEN 0x80000000 /* written extent */
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#define EXTENT_STATUS_UNWRITTEN 0x40000000 /* unwritten extent */
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#define EXTENT_STATUS_DELAYED 0x20000000 /* delayed extent */
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#define EXTENT_STATUS_HOLE 0x10000000 /* hole */
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#define EXTENT_STATUS_FLAGS (EXTENT_STATUS_WRITTEN | \
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EXTENT_STATUS_UNWRITTEN | \
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EXTENT_STATUS_DELAYED | \
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EXTENT_STATUS_HOLE)
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struct extent_status {
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struct rb_node rb_node;
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ext4_lblk_t es_lblk; /* first logical block extent covers */
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ext4_lblk_t es_len; /* length of extent in block */
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ext4_fsblk_t es_pblk; /* first physical block */
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};
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struct ext4_es_tree {
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struct rb_root root;
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struct extent_status *cache_es; /* recently accessed extent */
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};
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extern int __init ext4_init_es(void);
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extern void ext4_exit_es(void);
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extern void ext4_es_init_tree(struct ext4_es_tree *tree);
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extern int ext4_es_insert_extent(struct inode *inode, ext4_lblk_t lblk,
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ext4_lblk_t len, ext4_fsblk_t pblk,
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unsigned long long status);
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extern int ext4_es_remove_extent(struct inode *inode, ext4_lblk_t lblk,
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ext4_lblk_t len);
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extern void ext4_es_find_delayed_extent(struct inode *inode, ext4_lblk_t lblk,
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struct extent_status *es);
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extern int ext4_es_lookup_extent(struct inode *inode, ext4_lblk_t lblk,
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struct extent_status *es);
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static inline int ext4_es_is_written(struct extent_status *es)
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{
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return (es->es_pblk & EXTENT_STATUS_WRITTEN);
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}
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static inline int ext4_es_is_unwritten(struct extent_status *es)
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{
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return (es->es_pblk & EXTENT_STATUS_UNWRITTEN);
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}
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static inline int ext4_es_is_delayed(struct extent_status *es)
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{
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return (es->es_pblk & EXTENT_STATUS_DELAYED);
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}
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static inline int ext4_es_is_hole(struct extent_status *es)
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{
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return (es->es_pblk & EXTENT_STATUS_HOLE);
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}
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static inline ext4_fsblk_t ext4_es_status(struct extent_status *es)
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{
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return (es->es_pblk & EXTENT_STATUS_FLAGS);
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}
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static inline ext4_fsblk_t ext4_es_pblock(struct extent_status *es)
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{
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return (es->es_pblk & ~EXTENT_STATUS_FLAGS);
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}
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static inline void ext4_es_store_pblock(struct extent_status *es,
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ext4_fsblk_t pb)
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{
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ext4_fsblk_t block;
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block = (pb & ~EXTENT_STATUS_FLAGS) |
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(es->es_pblk & EXTENT_STATUS_FLAGS);
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es->es_pblk = block;
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}
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static inline void ext4_es_store_status(struct extent_status *es,
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unsigned long long status)
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{
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ext4_fsblk_t block;
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block = (status & EXTENT_STATUS_FLAGS) |
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(es->es_pblk & ~EXTENT_STATUS_FLAGS);
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es->es_pblk = block;
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}
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#endif /* _EXT4_EXTENTS_STATUS_H */
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