diff options
| -rw-r--r-- | include/linux/mm.h | 1 | ||||
| -rw-r--r-- | mm/gup.c | 24 |
2 files changed, 25 insertions, 0 deletions
diff --git a/include/linux/mm.h b/include/linux/mm.h index ecf63d2b0582..f9de33ac2add 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -2524,6 +2524,7 @@ long pin_user_pages_unlocked(unsigned long start, unsigned long nr_pages, long memfd_pin_folios(struct file *memfd, loff_t start, loff_t end, struct folio **folios, unsigned int max_folios, pgoff_t *offset); +int folio_add_pins(struct folio *folio, unsigned int pins); int get_user_pages_fast(unsigned long start, int nr_pages, unsigned int gup_flags, struct page **pages); @@ -3717,3 +3717,27 @@ err: return ret; } EXPORT_SYMBOL_GPL(memfd_pin_folios); + +/** + * folio_add_pins() - add pins to an already-pinned folio + * @folio: the folio to add more pins to + * @pins: number of pins to add + * + * Try to add more pins to an already-pinned folio. The semantics + * of the pin (e.g., FOLL_WRITE) follow any existing pin and cannot + * be changed. + * + * This function is helpful when having obtained a pin on a large folio + * using memfd_pin_folios(), but wanting to logically unpin parts + * (e.g., individual pages) of the folio later, for example, using + * unpin_user_page_range_dirty_lock(). + * + * This is not the right interface to initially pin a folio. + */ +int folio_add_pins(struct folio *folio, unsigned int pins) +{ + VM_WARN_ON_ONCE(!folio_maybe_dma_pinned(folio)); + + return try_grab_folio(folio, pins, FOLL_PIN); +} +EXPORT_SYMBOL_GPL(folio_add_pins); |