diff options
| -rw-r--r-- | include/linux/highmem.h | 29 | ||||
| -rw-r--r-- | include/linux/page-flags.h | 1 |
2 files changed, 30 insertions, 0 deletions
diff --git a/include/linux/highmem.h b/include/linux/highmem.h index e22509420ac6..348701dae77f 100644 --- a/include/linux/highmem.h +++ b/include/linux/highmem.h @@ -414,6 +414,35 @@ static inline void memzero_page(struct page *page, size_t offset, size_t len) } /** + * memcpy_from_file_folio - Copy some bytes from a file folio. + * @to: The destination buffer. + * @folio: The folio to copy from. + * @pos: The position in the file. + * @len: The maximum number of bytes to copy. + * + * Copy up to @len bytes from this folio. This may be limited by PAGE_SIZE + * if the folio comes from HIGHMEM, and by the size of the folio. + * + * Return: The number of bytes copied from the folio. + */ +static inline size_t memcpy_from_file_folio(char *to, struct folio *folio, + loff_t pos, size_t len) +{ + size_t offset = offset_in_folio(folio, pos); + char *from = kmap_local_folio(folio, offset); + + if (folio_test_highmem(folio)) + len = min_t(size_t, len, PAGE_SIZE - offset); + else + len = min(len, folio_size(folio) - offset); + + memcpy(to, from, len); + kunmap_local(from); + + return len; +} + +/** * folio_zero_segments() - Zero two byte ranges in a folio. * @folio: The folio to write to. * @start1: The first byte to zero. diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index 69e93a0c1277..a7e3a3405520 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -531,6 +531,7 @@ PAGEFLAG(Readahead, readahead, PF_NO_COMPOUND) * available at this point. */ #define PageHighMem(__p) is_highmem_idx(page_zonenum(__p)) +#define folio_test_highmem(__f) is_highmem_idx(folio_zonenum(__f)) #else PAGEFLAG_FALSE(HighMem, highmem) #endif |