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btrfs: handle sectorsize < PAGE_SIZE case for extent buffer accessors 

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
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
fs/btrfs/ctree.c
View File

@ -1683,9 +1683,10 @@ static noinline int generic_bin_search(struct extent_buffer *eb,
oip = offset_in_page(offset);
if (oip + key_size <= PAGE_SIZE) {
const unsigned long idx = offset >> PAGE_SHIFT;
const unsigned long idx = get_eb_page_index(offset);
char *kaddr = page_address(eb->pages[idx]);
oip = get_eb_offset_in_page(eb, offset);
tmp = (struct btrfs_disk_key *)(kaddr + oip);
} else {
read_extent_buffer(eb, &unaligned, offset, key_size);

38
fs/btrfs/ctree.h
View File

@ -1552,13 +1552,14 @@ static inline void btrfs_set_token_##name(struct btrfs_map_token *token,\
#define BTRFS_SETGET_HEADER_FUNCS(name, type, member, bits) \
static inline u##bits btrfs_##name(const struct extent_buffer *eb) \
{ \
const type *p = page_address(eb->pages[0]); \
const type *p = page_address(eb->pages[0]) + \
offset_in_page(eb->start); \
return get_unaligned_le##bits(&p->member); \
} \
static inline void btrfs_set_##name(const struct extent_buffer *eb, \
u##bits val) \
{ \
type *p = page_address(eb->pages[0]); \
type *p = page_address(eb->pages[0]) + offset_in_page(eb->start); \
put_unaligned_le##bits(val, &p->member); \
}
@ -3366,6 +3367,39 @@ static inline void assertfail(const char *expr, const char* file, int line) { }
#define ASSERT(expr) (void)(expr)
#endif
/*
* Get the correct offset inside the page of extent buffer.
*
* @eb: target extent buffer
* @start: offset inside the extent buffer
*
* Will handle both sectorsize == PAGE_SIZE and sectorsize < PAGE_SIZE cases.
*/
static inline size_t get_eb_offset_in_page(const struct extent_buffer *eb,
unsigned long offset)
{
/*
* For sectorsize == PAGE_SIZE case, eb->start will always be aligned
* to PAGE_SIZE, thus adding it won't cause any difference.
*
* For sectorsize < PAGE_SIZE, we must only read the data that belongs
* to the eb, thus we have to take the eb->start into consideration.
*/
return offset_in_page(offset + eb->start);
}
static inline unsigned long get_eb_page_index(unsigned long offset)
{
/*
* For sectorsize == PAGE_SIZE case, plain >> PAGE_SHIFT is enough.
*
* For sectorsize < PAGE_SIZE case, we only support 64K PAGE_SIZE,
* and have ensured that all tree blocks are contained in one page,
* thus we always get index == 0.
*/
return offset >> PAGE_SHIFT;
}
/*
* Use that for functions that are conditionally exported for sanity tests but
* otherwise static

64
fs/btrfs/extent_io.c
View File

@ -5703,12 +5703,12 @@ void read_extent_buffer(const struct extent_buffer *eb, void *dstv,
struct page *page;
char *kaddr;
char *dst = (char *)dstv;
unsigned long i = start >> PAGE_SHIFT;
unsigned long i = get_eb_page_index(start);
if (check_eb_range(eb, start, len))
return;
offset = offset_in_page(start);
offset = get_eb_offset_in_page(eb, start);
while (len > 0) {
page = eb->pages[i];
@ -5733,13 +5733,13 @@ int read_extent_buffer_to_user_nofault(const struct extent_buffer *eb,
struct page *page;
char *kaddr;
char __user *dst = (char __user *)dstv;
unsigned long i = start >> PAGE_SHIFT;
unsigned long i = get_eb_page_index(start);
int ret = 0;
WARN_ON(start > eb->len);
WARN_ON(start + len > eb->start + eb->len);
offset = offset_in_page(start);
offset = get_eb_offset_in_page(eb, start);
while (len > 0) {
page = eb->pages[i];
@ -5768,13 +5768,13 @@ int memcmp_extent_buffer(const struct extent_buffer *eb, const void *ptrv,
struct page *page;
char *kaddr;
char *ptr = (char *)ptrv;
unsigned long i = start >> PAGE_SHIFT;
unsigned long i = get_eb_page_index(start);
int ret = 0;
if (check_eb_range(eb, start, len))
return -EINVAL;
offset = offset_in_page(start);
offset = get_eb_offset_in_page(eb, start);
while (len > 0) {
page = eb->pages[i];
@ -5800,7 +5800,7 @@ void write_extent_buffer_chunk_tree_uuid(const struct extent_buffer *eb,
char *kaddr;
WARN_ON(!PageUptodate(eb->pages[0]));
kaddr = page_address(eb->pages[0]);
kaddr = page_address(eb->pages[0]) + get_eb_offset_in_page(eb, 0);
memcpy(kaddr + offsetof(struct btrfs_header, chunk_tree_uuid), srcv,
BTRFS_FSID_SIZE);
}
@ -5810,7 +5810,7 @@ void write_extent_buffer_fsid(const struct extent_buffer *eb, const void *srcv)
char *kaddr;
WARN_ON(!PageUptodate(eb->pages[0]));
kaddr = page_address(eb->pages[0]);
kaddr = page_address(eb->pages[0]) + get_eb_offset_in_page(eb, 0);
memcpy(kaddr + offsetof(struct btrfs_header, fsid), srcv,
BTRFS_FSID_SIZE);
}
@ -5823,12 +5823,12 @@ void write_extent_buffer(const struct extent_buffer *eb, const void *srcv,
struct page *page;
char *kaddr;
char *src = (char *)srcv;
unsigned long i = start >> PAGE_SHIFT;
unsigned long i = get_eb_page_index(start);
if (check_eb_range(eb, start, len))
return;
offset = offset_in_page(start);
offset = get_eb_offset_in_page(eb, start);
while (len > 0) {
page = eb->pages[i];
@ -5852,12 +5852,12 @@ void memzero_extent_buffer(const struct extent_buffer *eb, unsigned long start,
size_t offset;
struct page *page;
char *kaddr;
unsigned long i = start >> PAGE_SHIFT;
unsigned long i = get_eb_page_index(start);
if (check_eb_range(eb, start, len))
return;
offset = offset_in_page(start);
offset = get_eb_offset_in_page(eb, start);
while (len > 0) {
page = eb->pages[i];
@ -5881,10 +5881,20 @@ void copy_extent_buffer_full(const struct extent_buffer *dst,
ASSERT(dst->len == src->len);
num_pages = num_extent_pages(dst);
for (i = 0; i < num_pages; i++)
copy_page(page_address(dst->pages[i]),
page_address(src->pages[i]));
if (dst->fs_info->sectorsize == PAGE_SIZE) {
num_pages = num_extent_pages(dst);
for (i = 0; i < num_pages; i++)
copy_page(page_address(dst->pages[i]),
page_address(src->pages[i]));
} else {
size_t src_offset = get_eb_offset_in_page(src, 0);
size_t dst_offset = get_eb_offset_in_page(dst, 0);
ASSERT(src->fs_info->sectorsize < PAGE_SIZE);
memcpy(page_address(dst->pages[0]) + dst_offset,
page_address(src->pages[0]) + src_offset,
src->len);
}
}
void copy_extent_buffer(const struct extent_buffer *dst,
@ -5897,7 +5907,7 @@ void copy_extent_buffer(const struct extent_buffer *dst,
size_t offset;
struct page *page;
char *kaddr;
unsigned long i = dst_offset >> PAGE_SHIFT;
unsigned long i = get_eb_page_index(dst_offset);
if (check_eb_range(dst, dst_offset, len) ||
check_eb_range(src, src_offset, len))
@ -5905,7 +5915,7 @@ void copy_extent_buffer(const struct extent_buffer *dst,
WARN_ON(src->len != dst_len);
offset = offset_in_page(dst_offset);
offset = get_eb_offset_in_page(dst, dst_offset);
while (len > 0) {
page = dst->pages[i];
@ -5949,7 +5959,7 @@ static inline void eb_bitmap_offset(const struct extent_buffer *eb,
* the bitmap item in the extent buffer + the offset of the byte in the
* bitmap item.
*/
offset = start + byte_offset;
offset = start + offset_in_page(eb->start) + byte_offset;
*page_index = offset >> PAGE_SHIFT;
*page_offset = offset_in_page(offset);
@ -6103,11 +6113,11 @@ void memcpy_extent_buffer(const struct extent_buffer *dst,
return;
while (len > 0) {
dst_off_in_page = offset_in_page(dst_offset);
src_off_in_page = offset_in_page(src_offset);
dst_off_in_page = get_eb_offset_in_page(dst, dst_offset);
src_off_in_page = get_eb_offset_in_page(dst, src_offset);
dst_i = dst_offset >> PAGE_SHIFT;
src_i = src_offset >> PAGE_SHIFT;
dst_i = get_eb_page_index(dst_offset);
src_i = get_eb_page_index(src_offset);
cur = min(len, (unsigned long)(PAGE_SIZE -
src_off_in_page));
@ -6143,11 +6153,11 @@ void memmove_extent_buffer(const struct extent_buffer *dst,
return;
}
while (len > 0) {
dst_i = dst_end >> PAGE_SHIFT;
src_i = src_end >> PAGE_SHIFT;
dst_i = get_eb_page_index(dst_end);
src_i = get_eb_page_index(src_end);
dst_off_in_page = offset_in_page(dst_end);
src_off_in_page = offset_in_page(src_end);
dst_off_in_page = get_eb_offset_in_page(dst, dst_end);
src_off_in_page = get_eb_offset_in_page(dst, src_end);
cur = min_t(unsigned long, len, src_off_in_page + 1);
cur = min(cur, dst_off_in_page + 1);

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; \