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2e438442ba
The mod_start and mod_len fields of struct extent_map were introduced by
commit 4e2f84e63d ("Btrfs: improve fsync by filtering extents that we
want") in order to avoid too low performance when fsyncing a file that
keeps getting extent maps merge, because it resulted in each fsync logging
again csum ranges that were already merged before.
We don't need this anymore as extent maps in the list of modified extents
are never merged with other extent maps and once we log an extent map we
remove it from the list of modified extent maps, so it's never logged
twice.
So remove the mod_start and mod_len fields from struct extent_map and use
instead the start and len fields when logging checksums in the fast fsync
path. This also makes EXTENT_FLAG_FILLING unused so remove it as well.
Running the reproducer from the commit mentioned before, with a larger
number of extents and against a null block device, so that IO is fast
and we can better see any impact from searching checksums items and
logging them, gave the following results from dd:
Before this change:
409600000 bytes (410 MB, 391 MiB) copied, 22.948 s, 17.8 MB/s
After this change:
409600000 bytes (410 MB, 391 MiB) copied, 22.9997 s, 17.8 MB/s
So no changes in throughput.
The test was done in a release kernel (non-debug, Debian's default kernel
config) and its steps are the following:
$ mkfs.btrfs -f /dev/nullb0
$ mount /dev/sdb /mnt
$ dd if=/dev/zero of=/mnt/foobar bs=4k count=100000 oflag=sync
$ umount /mnt
This also reduces the size of struct extent_map from 128 bytes down to 112
bytes, so now we can have 36 extents maps per 4K page instead of 32.
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
145 lines
4 KiB
C
145 lines
4 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef BTRFS_EXTENT_MAP_H
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#define BTRFS_EXTENT_MAP_H
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#include <linux/compiler_types.h>
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#include <linux/rwlock_types.h>
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#include <linux/rbtree.h>
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#include <linux/list.h>
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#include <linux/refcount.h>
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#include "misc.h"
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#include "extent_map.h"
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#include "compression.h"
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struct btrfs_inode;
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struct btrfs_fs_info;
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#define EXTENT_MAP_LAST_BYTE ((u64)-4)
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#define EXTENT_MAP_HOLE ((u64)-3)
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#define EXTENT_MAP_INLINE ((u64)-2)
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/* bits for the extent_map::flags field */
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enum {
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/* this entry not yet on disk, don't free it */
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ENUM_BIT(EXTENT_FLAG_PINNED),
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ENUM_BIT(EXTENT_FLAG_COMPRESS_ZLIB),
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ENUM_BIT(EXTENT_FLAG_COMPRESS_LZO),
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ENUM_BIT(EXTENT_FLAG_COMPRESS_ZSTD),
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/* pre-allocated extent */
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ENUM_BIT(EXTENT_FLAG_PREALLOC),
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/* Logging this extent */
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ENUM_BIT(EXTENT_FLAG_LOGGING),
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/* This em is merged from two or more physically adjacent ems */
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ENUM_BIT(EXTENT_FLAG_MERGED),
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};
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/*
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* Keep this structure as compact as possible, as we can have really large
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* amounts of allocated extent maps at any time.
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*/
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struct extent_map {
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struct rb_node rb_node;
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/* all of these are in bytes */
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u64 start;
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u64 len;
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u64 orig_start;
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u64 orig_block_len;
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u64 ram_bytes;
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u64 block_start;
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u64 block_len;
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/*
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* Generation of the extent map, for merged em it's the highest
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* generation of all merged ems.
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* For non-merged extents, it's from btrfs_file_extent_item::generation.
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*/
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u64 generation;
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u32 flags;
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refcount_t refs;
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struct list_head list;
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};
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struct extent_map_tree {
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struct rb_root_cached map;
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struct list_head modified_extents;
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rwlock_t lock;
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};
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struct btrfs_inode;
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static inline void extent_map_set_compression(struct extent_map *em,
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enum btrfs_compression_type type)
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{
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if (type == BTRFS_COMPRESS_ZLIB)
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em->flags |= EXTENT_FLAG_COMPRESS_ZLIB;
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else if (type == BTRFS_COMPRESS_LZO)
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em->flags |= EXTENT_FLAG_COMPRESS_LZO;
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else if (type == BTRFS_COMPRESS_ZSTD)
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em->flags |= EXTENT_FLAG_COMPRESS_ZSTD;
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}
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static inline enum btrfs_compression_type extent_map_compression(const struct extent_map *em)
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{
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if (em->flags & EXTENT_FLAG_COMPRESS_ZLIB)
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return BTRFS_COMPRESS_ZLIB;
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if (em->flags & EXTENT_FLAG_COMPRESS_LZO)
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return BTRFS_COMPRESS_LZO;
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if (em->flags & EXTENT_FLAG_COMPRESS_ZSTD)
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return BTRFS_COMPRESS_ZSTD;
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return BTRFS_COMPRESS_NONE;
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}
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/*
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* More efficient way to determine if extent is compressed, instead of using
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* 'extent_map_compression() != BTRFS_COMPRESS_NONE'.
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*/
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static inline bool extent_map_is_compressed(const struct extent_map *em)
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{
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return (em->flags & (EXTENT_FLAG_COMPRESS_ZLIB |
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EXTENT_FLAG_COMPRESS_LZO |
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EXTENT_FLAG_COMPRESS_ZSTD)) != 0;
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}
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static inline int extent_map_in_tree(const struct extent_map *em)
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{
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return !RB_EMPTY_NODE(&em->rb_node);
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}
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static inline u64 extent_map_end(const struct extent_map *em)
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{
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if (em->start + em->len < em->start)
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return (u64)-1;
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return em->start + em->len;
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}
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void extent_map_tree_init(struct extent_map_tree *tree);
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struct extent_map *lookup_extent_mapping(struct extent_map_tree *tree,
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u64 start, u64 len);
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void remove_extent_mapping(struct extent_map_tree *tree, struct extent_map *em);
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int split_extent_map(struct btrfs_inode *inode, u64 start, u64 len, u64 pre,
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u64 new_logical);
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struct extent_map *alloc_extent_map(void);
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void free_extent_map(struct extent_map *em);
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int __init extent_map_init(void);
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void __cold extent_map_exit(void);
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int unpin_extent_cache(struct btrfs_inode *inode, u64 start, u64 len, u64 gen);
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void clear_em_logging(struct extent_map_tree *tree, struct extent_map *em);
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struct extent_map *search_extent_mapping(struct extent_map_tree *tree,
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u64 start, u64 len);
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int btrfs_add_extent_mapping(struct btrfs_fs_info *fs_info,
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struct extent_map_tree *em_tree,
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struct extent_map **em_in, u64 start, u64 len);
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void btrfs_drop_extent_map_range(struct btrfs_inode *inode,
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u64 start, u64 end,
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bool skip_pinned);
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int btrfs_replace_extent_map_range(struct btrfs_inode *inode,
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struct extent_map *new_em,
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bool modified);
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#endif
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