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58383c6866
Reading/writing 1 byte (u8) is a special case compared to the others as
it's always contained in the folio we find, so the split memcpy will
never be needed. Turn it to a compile-time check that the memcpy part
can be optimized out.
The stack usage is reduced:
btrfs_set_8 -16 (32 -> 16)
btrfs_get_8 -16 (24 -> 8)
Code size reduction:
text data bss dec hex filename
1454951 115665 16088 1586704 183610 pre/btrfs.ko
1454691 115665 16088 1586444 18350c post/btrfs.ko
DELTA: -260
Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: David Sterba <dsterba@suse.com>
105 lines
3.7 KiB
C
105 lines
3.7 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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/*
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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]); \
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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 + oil); \
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\
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memcpy(lebytes, kaddr + oil, part); \
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kaddr = folio_address(eb->folios[idx + 1]); \
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memcpy(lebytes + part, kaddr, sizeof(u##bits) - part); \
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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]); \
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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 + oil); \
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return; \
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} \
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\
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put_unaligned_le##bits(val, lebytes); \
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memcpy(kaddr + oil, 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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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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