For replacing a page inside page cache, we assume the huge page has been splitted before getting here.
For adding a new page to page cache, huge page support has been added. Also refactor the shm_add_to_page_cache function. Signed-off-by: Ning Qu <[email protected]> --- mm/shmem.c | 97 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++------ 1 file changed, 88 insertions(+), 9 deletions(-) diff --git a/mm/shmem.c b/mm/shmem.c index a857ba8..447bd14 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -277,27 +277,23 @@ static bool shmem_confirm_swap(struct address_space *mapping, } /* - * Like add_to_page_cache_locked, but error if expected item has gone. + * Replace the swap entry with page cache entry */ -static int shmem_add_to_page_cache(struct page *page, +static int shmem_replace_page_page_cache(struct page *page, struct address_space *mapping, pgoff_t index, gfp_t gfp, void *expected) { int error; - VM_BUG_ON(!PageLocked(page)); - VM_BUG_ON(!PageSwapBacked(page)); + BUG_ON(PageTransHugeCache(page)); page_cache_get(page); page->mapping = mapping; page->index = index; spin_lock_irq(&mapping->tree_lock); - if (!expected) - error = radix_tree_insert(&mapping->page_tree, index, page); - else - error = shmem_radix_tree_replace(mapping, index, expected, - page); + + error = shmem_radix_tree_replace(mapping, index, expected, page); if (!error) { mapping->nrpages++; __inc_zone_page_state(page, NR_FILE_PAGES); @@ -312,6 +308,87 @@ static int shmem_add_to_page_cache(struct page *page, } /* + * Insert new page into with page cache + */ +static int shmem_insert_page_page_cache(struct page *page, + struct address_space *mapping, + pgoff_t index, gfp_t gfp) +{ + int error; + int i, nr; + + if (PageTransHugeCache(page)) + BUILD_BUG_ON(HPAGE_CACHE_NR > RADIX_TREE_PRELOAD_NR); + + nr = hpagecache_nr_pages(page); + + error = radix_tree_maybe_preload_contig(nr, gfp & ~__GFP_HIGHMEM); + if (error) + return error; + + spin_lock_irq(&mapping->tree_lock); + page_cache_get(page); + page->index = index; + page->mapping = mapping; + for (i = 0; i < nr; i++) { + error = radix_tree_insert(&mapping->page_tree, + index + i, page); + /* + * In the midle of THP we can collide with small page which was + * established before THP page cache is enabled or by other VMA + * with bad alignement (most likely MAP_FIXED). + */ + if (error) { + i--; /* failed to insert anything at offset + i */ + goto err; + } + } + radix_tree_preload_end(); + mapping->nrpages += nr; + __mod_zone_page_state(page_zone(page), NR_FILE_PAGES, nr); + __mod_zone_page_state(page_zone(page), NR_SHMEM, nr); + if (PageTransHugeCache(page)) + __inc_zone_page_state(page, NR_FILE_TRANSPARENT_HUGEPAGES); + spin_unlock_irq(&mapping->tree_lock); + return 0; +err: + radix_tree_preload_end(); + if (i != 0) + error = -ENOSPC; /* no space for a huge page */ + + /* Leave page->index set: truncation relies upon it */ + page->mapping = NULL; + for (; i >= 0; i--) + radix_tree_delete(&mapping->page_tree, index + i); + + spin_unlock_irq(&mapping->tree_lock); + page_cache_release(page); + return error; +} + +/* + * Like add_to_page_cache_locked, but error if expected item has gone. + */ +static int shmem_add_to_page_cache(struct page *page, + struct address_space *mapping, + pgoff_t index, gfp_t gfp, void *expected) +{ + int error; + + VM_BUG_ON(!PageLocked(page)); + VM_BUG_ON(!PageSwapBacked(page)); + + if (expected) { + BUG_ON(PageTransHugeCache(page)); + error = shmem_replace_page_page_cache(page, mapping, index, gfp, + expected); + } else + error = shmem_insert_page_page_cache(page, mapping, index, gfp); + + return error; +} + +/* * Like delete_from_page_cache, but substitutes swap for page. */ static void shmem_delete_from_page_cache(struct page *page, void *radswap) @@ -319,6 +396,8 @@ static void shmem_delete_from_page_cache(struct page *page, void *radswap) struct address_space *mapping = page->mapping; int error; + BUG_ON(PageTransHugeCache(page)); + spin_lock_irq(&mapping->tree_lock); error = shmem_radix_tree_replace(mapping, page->index, page, radswap); page->mapping = NULL; -- 1.8.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
