diff options
Diffstat (limited to 'fs/btrfs/struct-funcs.c')
| -rw-r--r-- | fs/btrfs/struct-funcs.c | 223 |
1 files changed, 112 insertions, 111 deletions
diff --git a/fs/btrfs/struct-funcs.c b/fs/btrfs/struct-funcs.c index 73f7987143df..079b059818e9 100644 --- a/fs/btrfs/struct-funcs.c +++ b/fs/btrfs/struct-funcs.c @@ -17,151 +17,152 @@ static inline void put_unaligned_le8(u8 val, void *p) *(u8 *)p = val; } +static bool check_setget_bounds(const struct extent_buffer *eb, + const void *ptr, unsigned off, int size) +{ + const unsigned long member_offset = (unsigned long)ptr + off; + + if (member_offset > eb->len) { + btrfs_warn(eb->fs_info, + "bad eb member start: ptr 0x%lx start %llu member offset %lu size %d", + (unsigned long)ptr, eb->start, member_offset, size); + return false; + } + if (member_offset + size > eb->len) { + btrfs_warn(eb->fs_info, + "bad eb member end: ptr 0x%lx start %llu member offset %lu size %d", + (unsigned long)ptr, eb->start, member_offset, size); + return false; + } + + return true; +} + /* - * this is some deeply nasty code. + * 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. * - * The end result is that anyone who #includes ctree.h gets a - * declaration for the btrfs_set_foo functions and btrfs_foo functions, - * which are wrappers of btrfs_set_token_#bits functions and - * btrfs_get_token_#bits functions, which are defined in this file. + * Generic helpers: + * - btrfs_set_8 (for 8/16/32/64) + * - btrfs_get_8 (for 8/16/32/64) * - * These setget functions do all the extent_buffer related mapping - * required to efficiently read and write specific fields in the extent - * buffers. Every pointer to metadata items in btrfs is really just - * an unsigned long offset into the extent buffer which has been - * cast to a specific type. This gives us all the gcc type checking. + * Generic helpers with a token (cached address of the most recently accessed + * page): + * - btrfs_set_token_8 (for 8/16/32/64) + * - btrfs_get_token_8 (for 8/16/32/64) * - * The extent buffer api is used to do the page spanning work required to - * have a metadata blocksize different from the page size. + * 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. * - * There are 2 variants defined, one with a token pointer and one without. + * The extent buffer pages stored in the array pages do not form a contiguous + * phyusical 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_token_##bits(const struct extent_buffer *eb, \ - const void *ptr, unsigned long off, \ - struct btrfs_map_token *token) \ +u##bits btrfs_get_token_##bits(struct btrfs_map_token *token, \ + const void *ptr, unsigned long off) \ { \ - unsigned long part_offset = (unsigned long)ptr; \ - unsigned long offset = part_offset + off; \ - void *p; \ - int err; \ - char *kaddr; \ - unsigned long map_start; \ - unsigned long map_len; \ - int size = sizeof(u##bits); \ - u##bits res; \ + 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 int size = sizeof(u##bits); \ + u8 lebytes[sizeof(u##bits)]; \ + const int part = PAGE_SIZE - oip; \ \ ASSERT(token); \ - ASSERT(token->eb == eb); \ - \ - if (token->kaddr && token->offset <= offset && \ - (token->offset + PAGE_SIZE >= offset + size)) { \ - kaddr = token->kaddr; \ - p = kaddr + part_offset - token->offset; \ - res = get_unaligned_le##bits(p + off); \ - return res; \ + ASSERT(token->kaddr); \ + ASSERT(check_setget_bounds(token->eb, ptr, off, size)); \ + if (token->offset <= member_offset && \ + member_offset + size <= token->offset + PAGE_SIZE) { \ + return get_unaligned_le##bits(token->kaddr + oip); \ } \ - err = map_private_extent_buffer(eb, offset, size, \ - &kaddr, &map_start, &map_len); \ - if (err) { \ - __le##bits leres; \ + token->kaddr = page_address(token->eb->pages[idx]); \ + token->offset = idx << PAGE_SHIFT; \ + if (oip + size <= PAGE_SIZE) \ + return get_unaligned_le##bits(token->kaddr + oip); \ \ - read_extent_buffer(eb, &leres, offset, size); \ - return le##bits##_to_cpu(leres); \ - } \ - p = kaddr + part_offset - map_start; \ - res = get_unaligned_le##bits(p + off); \ - token->kaddr = kaddr; \ - token->offset = map_start; \ - return res; \ + memcpy(lebytes, token->kaddr + oip, part); \ + token->kaddr = page_address(token->eb->pages[idx + 1]); \ + token->offset = (idx + 1) << PAGE_SHIFT; \ + memcpy(lebytes + part, token->kaddr, size - part); \ + return get_unaligned_le##bits(lebytes); \ } \ u##bits btrfs_get_##bits(const struct extent_buffer *eb, \ const void *ptr, unsigned long off) \ { \ - unsigned long part_offset = (unsigned long)ptr; \ - unsigned long offset = part_offset + off; \ - void *p; \ - int err; \ - char *kaddr; \ - unsigned long map_start; \ - unsigned long map_len; \ - int size = sizeof(u##bits); \ - u##bits res; \ + 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; \ + char *kaddr = page_address(eb->pages[idx]); \ + const int size = sizeof(u##bits); \ + const int part = PAGE_SIZE - oip; \ + u8 lebytes[sizeof(u##bits)]; \ \ - err = map_private_extent_buffer(eb, offset, size, \ - &kaddr, &map_start, &map_len); \ - if (err) { \ - __le##bits leres; \ + ASSERT(check_setget_bounds(eb, ptr, off, size)); \ + if (oip + size <= PAGE_SIZE) \ + return get_unaligned_le##bits(kaddr + oip); \ \ - read_extent_buffer(eb, &leres, offset, size); \ - return le##bits##_to_cpu(leres); \ - } \ - p = kaddr + part_offset - map_start; \ - res = get_unaligned_le##bits(p + off); \ - return res; \ + memcpy(lebytes, kaddr + oip, part); \ + kaddr = page_address(eb->pages[idx + 1]); \ + memcpy(lebytes + part, kaddr, size - part); \ + return get_unaligned_le##bits(lebytes); \ } \ -void btrfs_set_token_##bits(struct extent_buffer *eb, \ +void btrfs_set_token_##bits(struct btrfs_map_token *token, \ const void *ptr, unsigned long off, \ - u##bits val, \ - struct btrfs_map_token *token) \ + u##bits val) \ { \ - unsigned long part_offset = (unsigned long)ptr; \ - unsigned long offset = part_offset + off; \ - void *p; \ - int err; \ - char *kaddr; \ - unsigned long map_start; \ - unsigned long map_len; \ - int size = sizeof(u##bits); \ + 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 int size = sizeof(u##bits); \ + u8 lebytes[sizeof(u##bits)]; \ + const int part = PAGE_SIZE - oip; \ \ ASSERT(token); \ - ASSERT(token->eb == eb); \ - \ - if (token->kaddr && token->offset <= offset && \ - (token->offset + PAGE_SIZE >= offset + size)) { \ - kaddr = token->kaddr; \ - p = kaddr + part_offset - token->offset; \ - put_unaligned_le##bits(val, p + off); \ + ASSERT(token->kaddr); \ + ASSERT(check_setget_bounds(token->eb, ptr, off, size)); \ + if (token->offset <= member_offset && \ + member_offset + size <= token->offset + PAGE_SIZE) { \ + put_unaligned_le##bits(val, token->kaddr + oip); \ return; \ } \ - err = map_private_extent_buffer(eb, offset, size, \ - &kaddr, &map_start, &map_len); \ - if (err) { \ - __le##bits val2; \ - \ - val2 = cpu_to_le##bits(val); \ - write_extent_buffer(eb, &val2, offset, size); \ + token->kaddr = page_address(token->eb->pages[idx]); \ + token->offset = idx << PAGE_SHIFT; \ + if (oip + size <= PAGE_SIZE) { \ + put_unaligned_le##bits(val, token->kaddr + oip); \ return; \ } \ - p = kaddr + part_offset - map_start; \ - put_unaligned_le##bits(val, p + off); \ - token->kaddr = kaddr; \ - token->offset = map_start; \ + put_unaligned_le##bits(val, lebytes); \ + memcpy(token->kaddr + oip, lebytes, part); \ + token->kaddr = page_address(token->eb->pages[idx + 1]); \ + token->offset = (idx + 1) << PAGE_SHIFT; \ + memcpy(token->kaddr, lebytes + part, size - part); \ } \ -void btrfs_set_##bits(struct extent_buffer *eb, void *ptr, \ +void btrfs_set_##bits(const struct extent_buffer *eb, void *ptr, \ unsigned long off, u##bits val) \ { \ - unsigned long part_offset = (unsigned long)ptr; \ - unsigned long offset = part_offset + off; \ - void *p; \ - int err; \ - char *kaddr; \ - unsigned long map_start; \ - unsigned long map_len; \ - int size = sizeof(u##bits); \ - \ - err = map_private_extent_buffer(eb, offset, size, \ - &kaddr, &map_start, &map_len); \ - if (err) { \ - __le##bits val2; \ + 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; \ + char *kaddr = page_address(eb->pages[idx]); \ + const int size = sizeof(u##bits); \ + const int part = PAGE_SIZE - oip; \ + u8 lebytes[sizeof(u##bits)]; \ \ - val2 = cpu_to_le##bits(val); \ - write_extent_buffer(eb, &val2, offset, size); \ + ASSERT(check_setget_bounds(eb, ptr, off, size)); \ + if (oip + size <= PAGE_SIZE) { \ + put_unaligned_le##bits(val, kaddr + oip); \ return; \ } \ - p = kaddr + part_offset - map_start; \ - put_unaligned_le##bits(val, p + off); \ + \ + put_unaligned_le##bits(val, lebytes); \ + memcpy(kaddr + oip, lebytes, part); \ + kaddr = page_address(eb->pages[idx + 1]); \ + memcpy(kaddr, lebytes + part, size - part); \ } DEFINE_BTRFS_SETGET_BITS(8) |