diff options
Diffstat (limited to 'fs/btrfs/accessors.c')
| -rw-r--r-- | fs/btrfs/accessors.c | 125 |
1 files changed, 125 insertions, 0 deletions
diff --git a/fs/btrfs/accessors.c b/fs/btrfs/accessors.c new file mode 100644 index 000000000000..1248aa2535d3 --- /dev/null +++ b/fs/btrfs/accessors.c @@ -0,0 +1,125 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2007 Oracle. All rights reserved. + */ + +#include <linux/unaligned.h> +#include "messages.h" +#include "extent_io.h" +#include "fs.h" +#include "accessors.h" + +static void __cold report_setget_bounds(const struct extent_buffer *eb, + const void *ptr, unsigned off, int size) +{ + unsigned long member_offset = (unsigned long)ptr + off; + + btrfs_warn(eb->fs_info, + "bad eb member %s: ptr 0x%lx start %llu member offset %lu size %d", + (member_offset > eb->len ? "start" : "end"), + (unsigned long)ptr, eb->start, member_offset, size); +} + +/* Copy bytes from @src1 and @src2 to @dest. */ +static __always_inline void memcpy_split_src(char *dest, const char *src1, + const char *src2, const size_t len1, + const size_t total) +{ + memcpy(dest, src1, len1); + memcpy(dest + len1, src2, total - len1); +} + +/* + * Macro templates that define helpers to read/write extent buffer data of a + * given size, that are also used via ctree.h for access to item members by + * specialized helpers. + * + * Generic helpers: + * - btrfs_set_8 (for 8/16/32/64) + * - btrfs_get_8 (for 8/16/32/64) + * + * The set/get functions handle data spanning two pages transparently, in case + * metadata block size is larger than page. Every pointer to metadata items is + * an offset into the extent buffer page array, cast to a specific type. This + * gives us all the type checking. + * + * The extent buffer pages stored in the array folios may not form a contiguous + * physical range, but the API functions assume the linear offset to the range + * from 0 to metadata node size. + */ + +#define DEFINE_BTRFS_SETGET_BITS(bits) \ +u##bits btrfs_get_##bits(const struct extent_buffer *eb, \ + const void *ptr, unsigned long off) \ +{ \ + const unsigned long member_offset = (unsigned long)ptr + off; \ + const unsigned long idx = get_eb_folio_index(eb, member_offset);\ + const unsigned long oif = get_eb_offset_in_folio(eb, \ + member_offset);\ + char *kaddr = folio_address(eb->folios[idx]) + oif; \ + const int part = eb->folio_size - oif; \ + u8 lebytes[sizeof(u##bits)]; \ + \ + if (unlikely(member_offset + sizeof(u##bits) > eb->len)) { \ + report_setget_bounds(eb, ptr, off, sizeof(u##bits)); \ + return 0; \ + } \ + if (INLINE_EXTENT_BUFFER_PAGES == 1 || sizeof(u##bits) == 1 || \ + likely(sizeof(u##bits) <= part)) \ + return get_unaligned_le##bits(kaddr); \ + \ + if (sizeof(u##bits) == 2) { \ + lebytes[0] = *kaddr; \ + kaddr = folio_address(eb->folios[idx + 1]); \ + lebytes[1] = *kaddr; \ + } else { \ + memcpy_split_src(lebytes, kaddr, \ + folio_address(eb->folios[idx + 1]), \ + part, sizeof(u##bits)); \ + } \ + return get_unaligned_le##bits(lebytes); \ +} \ +void btrfs_set_##bits(const struct extent_buffer *eb, void *ptr, \ + unsigned long off, u##bits val) \ +{ \ + const unsigned long member_offset = (unsigned long)ptr + off; \ + const unsigned long idx = get_eb_folio_index(eb, member_offset);\ + const unsigned long oif = get_eb_offset_in_folio(eb, \ + member_offset);\ + char *kaddr = folio_address(eb->folios[idx]) + oif; \ + const int part = eb->folio_size - oif; \ + u8 lebytes[sizeof(u##bits)]; \ + \ + if (unlikely(member_offset + sizeof(u##bits) > eb->len)) { \ + report_setget_bounds(eb, ptr, off, sizeof(u##bits)); \ + return; \ + } \ + if (INLINE_EXTENT_BUFFER_PAGES == 1 || sizeof(u##bits) == 1 || \ + likely(sizeof(u##bits) <= part)) { \ + put_unaligned_le##bits(val, kaddr); \ + return; \ + } \ + put_unaligned_le##bits(val, lebytes); \ + if (sizeof(u##bits) == 2) { \ + *kaddr = lebytes[0]; \ + kaddr = folio_address(eb->folios[idx + 1]); \ + *kaddr = lebytes[1]; \ + } else { \ + memcpy(kaddr, lebytes, part); \ + kaddr = folio_address(eb->folios[idx + 1]); \ + memcpy(kaddr, lebytes + part, sizeof(u##bits) - part); \ + } \ +} + +DEFINE_BTRFS_SETGET_BITS(8) +DEFINE_BTRFS_SETGET_BITS(16) +DEFINE_BTRFS_SETGET_BITS(32) +DEFINE_BTRFS_SETGET_BITS(64) + +void btrfs_node_key(const struct extent_buffer *eb, + struct btrfs_disk_key *disk_key, int nr) +{ + unsigned long ptr = btrfs_node_key_ptr_offset(eb, nr); + read_eb_member(eb, (struct btrfs_key_ptr *)ptr, + struct btrfs_key_ptr, key, disk_key); +} |