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btrfs: handle sectorsize < PAGE_SIZE case for extent buffer accessors

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To support sectorsize < PAGE_SIZE case, we need to take extra care of
extent buffer accessors.

Since sectorsize is smaller than PAGE_SIZE, one page can contain
multiple tree blocks, we must use eb->start to determine the real offset
to read/write for extent buffer accessors.

This patch introduces two helpers to do this:

- get_eb_page_index()
  This is to calculate the index to access extent_buffer::pages.
  It's just a simple wrapper around "start >> PAGE_SHIFT".

  For sectorsize == PAGE_SIZE case, nothing is changed.
  For sectorsize < PAGE_SIZE case, we always get index as 0, and
  the existing page shift also works.

- get_eb_offset_in_page()
  This is to calculate the offset to access extent_buffer::pages.
  This needs to take extent_buffer::start into consideration.

  For sectorsize == PAGE_SIZE case, extent_buffer::start is always
  aligned to PAGE_SIZE, thus adding extent_buffer::start to
  offset_in_page() won't change the result.
  For sectorsize < PAGE_SIZE case, adding extent_buffer::start gives
  us the correct offset to access.

This patch will touch the following parts to cover all extent buffer
accessors:

- BTRFS_SETGET_HEADER_FUNCS()
- read_extent_buffer()
- read_extent_buffer_to_user()
- memcmp_extent_buffer()
- write_extent_buffer_chunk_tree_uuid()
- write_extent_buffer_fsid()
- write_extent_buffer()
- memzero_extent_buffer()
- copy_extent_buffer_full()
- copy_extent_buffer()
- memcpy_extent_buffer()
- memmove_extent_buffer()
- btrfs_get_token_##bits()
- btrfs_get_##bits()
- btrfs_set_token_##bits()
- btrfs_set_##bits()
- generic_bin_search()

Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Qu Wenruo
2020-12-02 14:48:04 +08:00
committed by David Sterba
parent 4a3dc93843
commit 884b07d0f4
4 changed files with 85 additions and 38 deletions
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18
fs/btrfs/struct-funcs.c
View File

@@ -57,8 +57,9 @@ u##bits btrfs_get_token_##bits(struct btrfs_map_token *token, \
const void *ptr, unsigned long off) \
{ \
const unsigned long member_offset = (unsigned long)ptr + off; \
const unsigned long idx = member_offset >> PAGE_SHIFT; \
const unsigned long oip = offset_in_page(member_offset); \
const unsigned long idx = get_eb_page_index(member_offset); \
const unsigned long oip = get_eb_offset_in_page(token->eb, \
member_offset); \
const int size = sizeof(u##bits); \
u8 lebytes[sizeof(u##bits)]; \
const int part = PAGE_SIZE - oip; \
@@ -85,8 +86,8 @@ 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 oip = offset_in_page(member_offset); \
const unsigned long idx = member_offset >> PAGE_SHIFT; \
const unsigned long oip = get_eb_offset_in_page(eb, member_offset); \
const unsigned long idx = get_eb_page_index(member_offset); \
char *kaddr = page_address(eb->pages[idx]); \
const int size = sizeof(u##bits); \
const int part = PAGE_SIZE - oip; \
@@ -106,8 +107,9 @@ void btrfs_set_token_##bits(struct btrfs_map_token *token, \
u##bits val) \
{ \
const unsigned long member_offset = (unsigned long)ptr + off; \
const unsigned long idx = member_offset >> PAGE_SHIFT; \
const unsigned long oip = offset_in_page(member_offset); \
const unsigned long idx = get_eb_page_index(member_offset); \
const unsigned long oip = get_eb_offset_in_page(token->eb, \
member_offset); \
const int size = sizeof(u##bits); \
u8 lebytes[sizeof(u##bits)]; \
const int part = PAGE_SIZE - oip; \
@@ -136,8 +138,8 @@ 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 oip = offset_in_page(member_offset); \
const unsigned long idx = member_offset >> PAGE_SHIFT; \
const unsigned long oip = get_eb_offset_in_page(eb, member_offset); \
const unsigned long idx = get_eb_page_index(member_offset); \
char *kaddr = page_address(eb->pages[idx]); \
const int size = sizeof(u##bits); \
const int part = PAGE_SIZE - oip; \