diff options
| -rw-r--r-- | drivers/block/brd.c | 93 |
1 files changed, 24 insertions, 69 deletions
diff --git a/drivers/block/brd.c b/drivers/block/brd.c index bcad9b926b0c..2f71376afc71 100644 --- a/drivers/block/brd.c +++ b/drivers/block/brd.c @@ -19,7 +19,7 @@ #include <linux/highmem.h> #include <linux/mutex.h> #include <linux/pagemap.h> -#include <linux/radix-tree.h> +#include <linux/xarray.h> #include <linux/fs.h> #include <linux/slab.h> #include <linux/backing-dev.h> @@ -28,7 +28,7 @@ #include <linux/uaccess.h> /* - * Each block ramdisk device has a radix_tree brd_pages of pages that stores + * Each block ramdisk device has a xarray brd_pages of pages that stores * the pages containing the block device's contents. A brd page's ->index is * its offset in PAGE_SIZE units. This is similar to, but in no way connected * with, the kernel's pagecache or buffer cache (which sit above our block @@ -40,11 +40,9 @@ struct brd_device { struct list_head brd_list; /* - * Backing store of pages and lock to protect it. This is the contents - * of the block device. + * Backing store of pages. This is the contents of the block device. */ - spinlock_t brd_lock; - struct radix_tree_root brd_pages; + struct xarray brd_pages; u64 brd_nr_pages; }; @@ -56,21 +54,8 @@ static struct page *brd_lookup_page(struct brd_device *brd, sector_t sector) pgoff_t idx; struct page *page; - /* - * The page lifetime is protected by the fact that we have opened the - * device node -- brd pages will never be deleted under us, so we - * don't need any further locking or refcounting. - * - * This is strictly true for the radix-tree nodes as well (ie. we - * don't actually need the rcu_read_lock()), however that is not a - * documented feature of the radix-tree API so it is better to be - * safe here (we don't have total exclusion from radix tree updates - * here, only deletes). - */ - rcu_read_lock(); idx = sector >> PAGE_SECTORS_SHIFT; /* sector to page index */ - page = radix_tree_lookup(&brd->brd_pages, idx); - rcu_read_unlock(); + page = xa_load(&brd->brd_pages, idx); BUG_ON(page && page->index != idx); @@ -83,7 +68,7 @@ static struct page *brd_lookup_page(struct brd_device *brd, sector_t sector) static int brd_insert_page(struct brd_device *brd, sector_t sector, gfp_t gfp) { pgoff_t idx; - struct page *page; + struct page *page, *cur; int ret = 0; page = brd_lookup_page(brd, sector); @@ -94,71 +79,42 @@ static int brd_insert_page(struct brd_device *brd, sector_t sector, gfp_t gfp) if (!page) return -ENOMEM; - if (radix_tree_maybe_preload(gfp)) { - __free_page(page); - return -ENOMEM; - } + xa_lock(&brd->brd_pages); - spin_lock(&brd->brd_lock); idx = sector >> PAGE_SECTORS_SHIFT; page->index = idx; - if (radix_tree_insert(&brd->brd_pages, idx, page)) { + + cur = __xa_cmpxchg(&brd->brd_pages, idx, NULL, page, gfp); + + if (unlikely(cur)) { __free_page(page); - page = radix_tree_lookup(&brd->brd_pages, idx); - if (!page) - ret = -ENOMEM; - else if (page->index != idx) + ret = xa_err(cur); + if (!ret && (cur->index != idx)) ret = -EIO; } else { brd->brd_nr_pages++; } - spin_unlock(&brd->brd_lock); - radix_tree_preload_end(); + xa_unlock(&brd->brd_pages); + return ret; } /* - * Free all backing store pages and radix tree. This must only be called when + * Free all backing store pages and xarray. This must only be called when * there are no other users of the device. */ -#define FREE_BATCH 16 static void brd_free_pages(struct brd_device *brd) { - unsigned long pos = 0; - struct page *pages[FREE_BATCH]; - int nr_pages; - - do { - int i; - - nr_pages = radix_tree_gang_lookup(&brd->brd_pages, - (void **)pages, pos, FREE_BATCH); - - for (i = 0; i < nr_pages; i++) { - void *ret; - - BUG_ON(pages[i]->index < pos); - pos = pages[i]->index; - ret = radix_tree_delete(&brd->brd_pages, pos); - BUG_ON(!ret || ret != pages[i]); - __free_page(pages[i]); - } - - pos++; + struct page *page; + pgoff_t idx; - /* - * It takes 3.4 seconds to remove 80GiB ramdisk. - * So, we need cond_resched to avoid stalling the CPU. - */ - cond_resched(); + xa_for_each(&brd->brd_pages, idx, page) { + __free_page(page); + cond_resched_rcu(); + } - /* - * This assumes radix_tree_gang_lookup always returns as - * many pages as possible. If the radix-tree code changes, - * so will this have to. - */ - } while (nr_pages == FREE_BATCH); + xa_destroy(&brd->brd_pages); } /* @@ -372,8 +328,7 @@ static int brd_alloc(int i) brd->brd_number = i; list_add_tail(&brd->brd_list, &brd_devices); - spin_lock_init(&brd->brd_lock); - INIT_RADIX_TREE(&brd->brd_pages, GFP_ATOMIC); + xa_init(&brd->brd_pages); snprintf(buf, DISK_NAME_LEN, "ram%d", i); if (!IS_ERR_OR_NULL(brd_debugfs_dir)) |