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ae80748225
The case of a reading the bytes from 2 folios needs two memcpy()s, the
compiler does not emit calls but two inline loops.
Factoring out the code makes some improvement (stack, code) and in the
future will provide an optimized implementation as well. (The analogical
version with two destinations is not done as it increases stack usage
but can be done if needed.)
The address of the second folio is reordered before the first memcpy,
which leads to an optimization reusing the vmemmap_base and
page_offset_base (implementing folio_address()).
Stack usage reduction:
btrfs_get_32 -8 (32 -> 24)
btrfs_get_64 -8 (32 -> 24)
Code size reduction:
text data bss dec hex filename
1454279 115665 16088 1586032 183370 pre/btrfs.ko
1454229 115665 16088 1585982 18333e post/btrfs.ko
DELTA: -50
As this is the last patch in this series, here's the overall diff
starting and including commit "btrfs: accessors: simplify folio bounds
checks":
Stack:
btrfs_set_16 -72 (88 -> 16)
btrfs_get_32 -56 (80 -> 24)
btrfs_set_8 -72 (88 -> 16)
btrfs_set_64 -64 (88 -> 24)
btrfs_get_8 -72 (80 -> 8)
btrfs_get_16 -64 (80 -> 16)
btrfs_set_32 -64 (88 -> 24)
btrfs_get_64 -56 (80 -> 24)
NEW (48):
report_setget_bounds 48
LOST/NEW DELTA: +48
PRE/POST DELTA: -472
Code:
text data bss dec hex filename
1456601 115665 16088 1588354 183c82 pre/btrfs.ko
1454229 115665 16088 1585982 18333e post/btrfs.ko
DELTA: -2372
Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: David Sterba <dsterba@suse.com>
125 lines
4.2 KiB
C
125 lines
4.2 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (C) 2007 Oracle. All rights reserved.
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*/
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#include <linux/unaligned.h>
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#include "messages.h"
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#include "extent_io.h"
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#include "fs.h"
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#include "accessors.h"
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static void __cold report_setget_bounds(const struct extent_buffer *eb,
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const void *ptr, unsigned off, int size)
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{
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unsigned long member_offset = (unsigned long)ptr + off;
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btrfs_warn(eb->fs_info,
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"bad eb member %s: ptr 0x%lx start %llu member offset %lu size %d",
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(member_offset > eb->len ? "start" : "end"),
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(unsigned long)ptr, eb->start, member_offset, size);
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}
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/* Copy bytes from @src1 and @src2 to @dest. */
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static __always_inline void memcpy_split_src(char *dest, const char *src1,
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const char *src2, const size_t len1,
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const size_t total)
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{
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memcpy(dest, src1, len1);
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memcpy(dest + len1, src2, total - len1);
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}
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/*
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* Macro templates that define helpers to read/write extent buffer data of a
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* given size, that are also used via ctree.h for access to item members by
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* specialized helpers.
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*
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* Generic helpers:
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* - btrfs_set_8 (for 8/16/32/64)
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* - btrfs_get_8 (for 8/16/32/64)
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*
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* The set/get functions handle data spanning two pages transparently, in case
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* metadata block size is larger than page. Every pointer to metadata items is
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* an offset into the extent buffer page array, cast to a specific type. This
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* gives us all the type checking.
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*
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* The extent buffer pages stored in the array folios may not form a contiguous
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* phyusical range, but the API functions assume the linear offset to the range
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* from 0 to metadata node size.
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*/
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#define DEFINE_BTRFS_SETGET_BITS(bits) \
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u##bits btrfs_get_##bits(const struct extent_buffer *eb, \
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const void *ptr, unsigned long off) \
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{ \
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const unsigned long member_offset = (unsigned long)ptr + off; \
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const unsigned long idx = get_eb_folio_index(eb, member_offset);\
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const unsigned long oil = get_eb_offset_in_folio(eb, \
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member_offset);\
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char *kaddr = folio_address(eb->folios[idx]) + oil; \
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const int part = eb->folio_size - oil; \
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u8 lebytes[sizeof(u##bits)]; \
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\
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if (unlikely(member_offset + sizeof(u##bits) > eb->len)) { \
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report_setget_bounds(eb, ptr, off, sizeof(u##bits)); \
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return 0; \
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} \
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if (INLINE_EXTENT_BUFFER_PAGES == 1 || sizeof(u##bits) == 1 || \
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likely(sizeof(u##bits) <= part)) \
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return get_unaligned_le##bits(kaddr); \
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\
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if (sizeof(u##bits) == 2) { \
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lebytes[0] = *kaddr; \
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kaddr = folio_address(eb->folios[idx + 1]); \
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lebytes[1] = *kaddr; \
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} else { \
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memcpy_split_src(lebytes, kaddr, \
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folio_address(eb->folios[idx + 1]), \
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part, sizeof(u##bits)); \
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} \
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return get_unaligned_le##bits(lebytes); \
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} \
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void btrfs_set_##bits(const struct extent_buffer *eb, void *ptr, \
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unsigned long off, u##bits val) \
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{ \
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const unsigned long member_offset = (unsigned long)ptr + off; \
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const unsigned long idx = get_eb_folio_index(eb, member_offset);\
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const unsigned long oil = get_eb_offset_in_folio(eb, \
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member_offset);\
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char *kaddr = folio_address(eb->folios[idx]) + oil; \
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const int part = eb->folio_size - oil; \
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u8 lebytes[sizeof(u##bits)]; \
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\
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if (unlikely(member_offset + sizeof(u##bits) > eb->len)) { \
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report_setget_bounds(eb, ptr, off, sizeof(u##bits)); \
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return; \
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} \
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if (INLINE_EXTENT_BUFFER_PAGES == 1 || sizeof(u##bits) == 1 || \
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likely(sizeof(u##bits) <= part)) { \
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put_unaligned_le##bits(val, kaddr); \
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return; \
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} \
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put_unaligned_le##bits(val, lebytes); \
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if (sizeof(u##bits) == 2) { \
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*kaddr = lebytes[0]; \
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kaddr = folio_address(eb->folios[idx + 1]); \
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*kaddr = lebytes[1]; \
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} else { \
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memcpy(kaddr, lebytes, part); \
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kaddr = folio_address(eb->folios[idx + 1]); \
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memcpy(kaddr, lebytes + part, sizeof(u##bits) - part); \
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} \
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}
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DEFINE_BTRFS_SETGET_BITS(8)
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DEFINE_BTRFS_SETGET_BITS(16)
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DEFINE_BTRFS_SETGET_BITS(32)
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DEFINE_BTRFS_SETGET_BITS(64)
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void btrfs_node_key(const struct extent_buffer *eb,
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struct btrfs_disk_key *disk_key, int nr)
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{
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unsigned long ptr = btrfs_node_key_ptr_offset(eb, nr);
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read_eb_member(eb, (struct btrfs_key_ptr *)ptr,
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struct btrfs_key_ptr, key, disk_key);
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}
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