mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-14 04:46:46 +07:00
74d46992e0
This way we don't need a block_device structure to submit I/O. The block_device has different life time rules from the gendisk and request_queue and is usually only available when the block device node is open. Other callers need to explicitly create one (e.g. the lightnvm passthrough code, or the new nvme multipathing code). For the actual I/O path all that we need is the gendisk, which exists once per block device. But given that the block layer also does partition remapping we additionally need a partition index, which is used for said remapping in generic_make_request. Note that all the block drivers generally want request_queue or sometimes the gendisk, so this removes a layer of indirection all over the stack. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
599 lines
14 KiB
C
599 lines
14 KiB
C
/*
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* Ram backed block device driver.
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*
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* Copyright (C) 2007 Nick Piggin
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* Copyright (C) 2007 Novell Inc.
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*
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* Parts derived from drivers/block/rd.c, and drivers/block/loop.c, copyright
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* of their respective owners.
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*/
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#include <linux/init.h>
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#include <linux/initrd.h>
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#include <linux/module.h>
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#include <linux/moduleparam.h>
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#include <linux/major.h>
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#include <linux/blkdev.h>
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#include <linux/bio.h>
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#include <linux/highmem.h>
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#include <linux/mutex.h>
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#include <linux/radix-tree.h>
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#include <linux/fs.h>
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#include <linux/slab.h>
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#ifdef CONFIG_BLK_DEV_RAM_DAX
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#include <linux/pfn_t.h>
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#include <linux/dax.h>
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#include <linux/uio.h>
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#endif
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#include <linux/uaccess.h>
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#define SECTOR_SHIFT 9
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#define PAGE_SECTORS_SHIFT (PAGE_SHIFT - SECTOR_SHIFT)
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#define PAGE_SECTORS (1 << PAGE_SECTORS_SHIFT)
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/*
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* Each block ramdisk device has a radix_tree brd_pages of pages that stores
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* the pages containing the block device's contents. A brd page's ->index is
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* its offset in PAGE_SIZE units. This is similar to, but in no way connected
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* with, the kernel's pagecache or buffer cache (which sit above our block
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* device).
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*/
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struct brd_device {
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int brd_number;
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struct request_queue *brd_queue;
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struct gendisk *brd_disk;
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#ifdef CONFIG_BLK_DEV_RAM_DAX
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struct dax_device *dax_dev;
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#endif
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struct list_head brd_list;
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/*
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* Backing store of pages and lock to protect it. This is the contents
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* of the block device.
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*/
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spinlock_t brd_lock;
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struct radix_tree_root brd_pages;
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};
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/*
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* Look up and return a brd's page for a given sector.
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*/
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static DEFINE_MUTEX(brd_mutex);
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static struct page *brd_lookup_page(struct brd_device *brd, sector_t sector)
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{
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pgoff_t idx;
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struct page *page;
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/*
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* The page lifetime is protected by the fact that we have opened the
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* device node -- brd pages will never be deleted under us, so we
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* don't need any further locking or refcounting.
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*
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* This is strictly true for the radix-tree nodes as well (ie. we
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* don't actually need the rcu_read_lock()), however that is not a
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* documented feature of the radix-tree API so it is better to be
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* safe here (we don't have total exclusion from radix tree updates
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* here, only deletes).
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*/
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rcu_read_lock();
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idx = sector >> PAGE_SECTORS_SHIFT; /* sector to page index */
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page = radix_tree_lookup(&brd->brd_pages, idx);
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rcu_read_unlock();
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BUG_ON(page && page->index != idx);
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return page;
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}
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/*
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* Look up and return a brd's page for a given sector.
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* If one does not exist, allocate an empty page, and insert that. Then
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* return it.
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*/
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static struct page *brd_insert_page(struct brd_device *brd, sector_t sector)
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{
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pgoff_t idx;
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struct page *page;
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gfp_t gfp_flags;
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page = brd_lookup_page(brd, sector);
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if (page)
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return page;
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/*
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* Must use NOIO because we don't want to recurse back into the
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* block or filesystem layers from page reclaim.
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*
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* Cannot support DAX and highmem, because our ->direct_access
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* routine for DAX must return memory that is always addressable.
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* If DAX was reworked to use pfns and kmap throughout, this
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* restriction might be able to be lifted.
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*/
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gfp_flags = GFP_NOIO | __GFP_ZERO;
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#ifndef CONFIG_BLK_DEV_RAM_DAX
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gfp_flags |= __GFP_HIGHMEM;
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#endif
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page = alloc_page(gfp_flags);
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if (!page)
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return NULL;
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if (radix_tree_preload(GFP_NOIO)) {
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__free_page(page);
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return NULL;
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}
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spin_lock(&brd->brd_lock);
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idx = sector >> PAGE_SECTORS_SHIFT;
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page->index = idx;
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if (radix_tree_insert(&brd->brd_pages, idx, page)) {
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__free_page(page);
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page = radix_tree_lookup(&brd->brd_pages, idx);
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BUG_ON(!page);
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BUG_ON(page->index != idx);
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}
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spin_unlock(&brd->brd_lock);
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radix_tree_preload_end();
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return page;
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}
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/*
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* Free all backing store pages and radix tree. This must only be called when
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* there are no other users of the device.
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*/
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#define FREE_BATCH 16
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static void brd_free_pages(struct brd_device *brd)
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{
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unsigned long pos = 0;
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struct page *pages[FREE_BATCH];
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int nr_pages;
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do {
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int i;
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nr_pages = radix_tree_gang_lookup(&brd->brd_pages,
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(void **)pages, pos, FREE_BATCH);
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for (i = 0; i < nr_pages; i++) {
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void *ret;
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BUG_ON(pages[i]->index < pos);
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pos = pages[i]->index;
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ret = radix_tree_delete(&brd->brd_pages, pos);
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BUG_ON(!ret || ret != pages[i]);
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__free_page(pages[i]);
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}
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pos++;
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/*
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* This assumes radix_tree_gang_lookup always returns as
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* many pages as possible. If the radix-tree code changes,
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* so will this have to.
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*/
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} while (nr_pages == FREE_BATCH);
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}
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/*
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* copy_to_brd_setup must be called before copy_to_brd. It may sleep.
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*/
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static int copy_to_brd_setup(struct brd_device *brd, sector_t sector, size_t n)
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{
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unsigned int offset = (sector & (PAGE_SECTORS-1)) << SECTOR_SHIFT;
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size_t copy;
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copy = min_t(size_t, n, PAGE_SIZE - offset);
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if (!brd_insert_page(brd, sector))
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return -ENOSPC;
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if (copy < n) {
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sector += copy >> SECTOR_SHIFT;
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if (!brd_insert_page(brd, sector))
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return -ENOSPC;
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}
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return 0;
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}
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/*
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* Copy n bytes from src to the brd starting at sector. Does not sleep.
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*/
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static void copy_to_brd(struct brd_device *brd, const void *src,
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sector_t sector, size_t n)
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{
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struct page *page;
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void *dst;
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unsigned int offset = (sector & (PAGE_SECTORS-1)) << SECTOR_SHIFT;
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size_t copy;
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copy = min_t(size_t, n, PAGE_SIZE - offset);
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page = brd_lookup_page(brd, sector);
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BUG_ON(!page);
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dst = kmap_atomic(page);
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memcpy(dst + offset, src, copy);
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kunmap_atomic(dst);
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if (copy < n) {
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src += copy;
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sector += copy >> SECTOR_SHIFT;
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copy = n - copy;
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page = brd_lookup_page(brd, sector);
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BUG_ON(!page);
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dst = kmap_atomic(page);
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memcpy(dst, src, copy);
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kunmap_atomic(dst);
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}
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}
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/*
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* Copy n bytes to dst from the brd starting at sector. Does not sleep.
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*/
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static void copy_from_brd(void *dst, struct brd_device *brd,
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sector_t sector, size_t n)
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{
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struct page *page;
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void *src;
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unsigned int offset = (sector & (PAGE_SECTORS-1)) << SECTOR_SHIFT;
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size_t copy;
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copy = min_t(size_t, n, PAGE_SIZE - offset);
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page = brd_lookup_page(brd, sector);
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if (page) {
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src = kmap_atomic(page);
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memcpy(dst, src + offset, copy);
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kunmap_atomic(src);
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} else
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memset(dst, 0, copy);
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if (copy < n) {
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dst += copy;
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sector += copy >> SECTOR_SHIFT;
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copy = n - copy;
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page = brd_lookup_page(brd, sector);
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if (page) {
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src = kmap_atomic(page);
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memcpy(dst, src, copy);
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kunmap_atomic(src);
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} else
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memset(dst, 0, copy);
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}
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}
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/*
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* Process a single bvec of a bio.
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*/
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static int brd_do_bvec(struct brd_device *brd, struct page *page,
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unsigned int len, unsigned int off, bool is_write,
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sector_t sector)
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{
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void *mem;
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int err = 0;
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if (is_write) {
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err = copy_to_brd_setup(brd, sector, len);
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if (err)
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goto out;
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}
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mem = kmap_atomic(page);
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if (!is_write) {
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copy_from_brd(mem + off, brd, sector, len);
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flush_dcache_page(page);
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} else {
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flush_dcache_page(page);
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copy_to_brd(brd, mem + off, sector, len);
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}
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kunmap_atomic(mem);
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out:
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return err;
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}
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static blk_qc_t brd_make_request(struct request_queue *q, struct bio *bio)
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{
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struct brd_device *brd = bio->bi_disk->private_data;
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struct bio_vec bvec;
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sector_t sector;
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struct bvec_iter iter;
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sector = bio->bi_iter.bi_sector;
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if (bio_end_sector(bio) > get_capacity(bio->bi_disk))
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goto io_error;
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bio_for_each_segment(bvec, bio, iter) {
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unsigned int len = bvec.bv_len;
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int err;
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err = brd_do_bvec(brd, bvec.bv_page, len, bvec.bv_offset,
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op_is_write(bio_op(bio)), sector);
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if (err)
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goto io_error;
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sector += len >> SECTOR_SHIFT;
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}
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bio_endio(bio);
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return BLK_QC_T_NONE;
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io_error:
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bio_io_error(bio);
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return BLK_QC_T_NONE;
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}
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static int brd_rw_page(struct block_device *bdev, sector_t sector,
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struct page *page, bool is_write)
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{
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struct brd_device *brd = bdev->bd_disk->private_data;
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int err = brd_do_bvec(brd, page, PAGE_SIZE, 0, is_write, sector);
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page_endio(page, is_write, err);
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return err;
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}
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#ifdef CONFIG_BLK_DEV_RAM_DAX
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static long __brd_direct_access(struct brd_device *brd, pgoff_t pgoff,
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long nr_pages, void **kaddr, pfn_t *pfn)
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{
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struct page *page;
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if (!brd)
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return -ENODEV;
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page = brd_insert_page(brd, PFN_PHYS(pgoff) / 512);
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if (!page)
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return -ENOSPC;
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*kaddr = page_address(page);
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*pfn = page_to_pfn_t(page);
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return 1;
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}
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static long brd_dax_direct_access(struct dax_device *dax_dev,
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pgoff_t pgoff, long nr_pages, void **kaddr, pfn_t *pfn)
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{
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struct brd_device *brd = dax_get_private(dax_dev);
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return __brd_direct_access(brd, pgoff, nr_pages, kaddr, pfn);
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}
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static size_t brd_dax_copy_from_iter(struct dax_device *dax_dev, pgoff_t pgoff,
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void *addr, size_t bytes, struct iov_iter *i)
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{
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return copy_from_iter(addr, bytes, i);
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}
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static const struct dax_operations brd_dax_ops = {
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.direct_access = brd_dax_direct_access,
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.copy_from_iter = brd_dax_copy_from_iter,
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};
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#endif
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static const struct block_device_operations brd_fops = {
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.owner = THIS_MODULE,
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.rw_page = brd_rw_page,
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};
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/*
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* And now the modules code and kernel interface.
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*/
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static int rd_nr = CONFIG_BLK_DEV_RAM_COUNT;
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module_param(rd_nr, int, S_IRUGO);
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MODULE_PARM_DESC(rd_nr, "Maximum number of brd devices");
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unsigned long rd_size = CONFIG_BLK_DEV_RAM_SIZE;
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module_param(rd_size, ulong, S_IRUGO);
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MODULE_PARM_DESC(rd_size, "Size of each RAM disk in kbytes.");
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static int max_part = 1;
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module_param(max_part, int, S_IRUGO);
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MODULE_PARM_DESC(max_part, "Num Minors to reserve between devices");
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MODULE_LICENSE("GPL");
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MODULE_ALIAS_BLOCKDEV_MAJOR(RAMDISK_MAJOR);
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MODULE_ALIAS("rd");
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#ifndef MODULE
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/* Legacy boot options - nonmodular */
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static int __init ramdisk_size(char *str)
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{
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rd_size = simple_strtol(str, NULL, 0);
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return 1;
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}
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__setup("ramdisk_size=", ramdisk_size);
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#endif
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/*
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* The device scheme is derived from loop.c. Keep them in synch where possible
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* (should share code eventually).
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*/
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static LIST_HEAD(brd_devices);
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static DEFINE_MUTEX(brd_devices_mutex);
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static struct brd_device *brd_alloc(int i)
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{
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struct brd_device *brd;
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struct gendisk *disk;
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brd = kzalloc(sizeof(*brd), GFP_KERNEL);
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if (!brd)
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goto out;
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brd->brd_number = i;
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spin_lock_init(&brd->brd_lock);
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INIT_RADIX_TREE(&brd->brd_pages, GFP_ATOMIC);
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brd->brd_queue = blk_alloc_queue(GFP_KERNEL);
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if (!brd->brd_queue)
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goto out_free_dev;
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blk_queue_make_request(brd->brd_queue, brd_make_request);
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blk_queue_max_hw_sectors(brd->brd_queue, 1024);
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/* This is so fdisk will align partitions on 4k, because of
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* direct_access API needing 4k alignment, returning a PFN
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* (This is only a problem on very small devices <= 4M,
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* otherwise fdisk will align on 1M. Regardless this call
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* is harmless)
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*/
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blk_queue_physical_block_size(brd->brd_queue, PAGE_SIZE);
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disk = brd->brd_disk = alloc_disk(max_part);
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if (!disk)
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goto out_free_queue;
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disk->major = RAMDISK_MAJOR;
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disk->first_minor = i * max_part;
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disk->fops = &brd_fops;
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disk->private_data = brd;
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disk->queue = brd->brd_queue;
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disk->flags = GENHD_FL_EXT_DEVT;
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sprintf(disk->disk_name, "ram%d", i);
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set_capacity(disk, rd_size * 2);
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#ifdef CONFIG_BLK_DEV_RAM_DAX
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queue_flag_set_unlocked(QUEUE_FLAG_DAX, brd->brd_queue);
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brd->dax_dev = alloc_dax(brd, disk->disk_name, &brd_dax_ops);
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if (!brd->dax_dev)
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goto out_free_inode;
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#endif
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return brd;
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#ifdef CONFIG_BLK_DEV_RAM_DAX
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out_free_inode:
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kill_dax(brd->dax_dev);
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put_dax(brd->dax_dev);
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#endif
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out_free_queue:
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blk_cleanup_queue(brd->brd_queue);
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out_free_dev:
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kfree(brd);
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out:
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return NULL;
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}
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static void brd_free(struct brd_device *brd)
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{
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put_disk(brd->brd_disk);
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blk_cleanup_queue(brd->brd_queue);
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brd_free_pages(brd);
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kfree(brd);
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}
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static struct brd_device *brd_init_one(int i, bool *new)
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{
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struct brd_device *brd;
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*new = false;
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list_for_each_entry(brd, &brd_devices, brd_list) {
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if (brd->brd_number == i)
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goto out;
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}
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brd = brd_alloc(i);
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if (brd) {
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add_disk(brd->brd_disk);
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list_add_tail(&brd->brd_list, &brd_devices);
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}
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*new = true;
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out:
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return brd;
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}
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static void brd_del_one(struct brd_device *brd)
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{
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list_del(&brd->brd_list);
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|
#ifdef CONFIG_BLK_DEV_RAM_DAX
|
|
kill_dax(brd->dax_dev);
|
|
put_dax(brd->dax_dev);
|
|
#endif
|
|
del_gendisk(brd->brd_disk);
|
|
brd_free(brd);
|
|
}
|
|
|
|
static struct kobject *brd_probe(dev_t dev, int *part, void *data)
|
|
{
|
|
struct brd_device *brd;
|
|
struct kobject *kobj;
|
|
bool new;
|
|
|
|
mutex_lock(&brd_devices_mutex);
|
|
brd = brd_init_one(MINOR(dev) / max_part, &new);
|
|
kobj = brd ? get_disk(brd->brd_disk) : NULL;
|
|
mutex_unlock(&brd_devices_mutex);
|
|
|
|
if (new)
|
|
*part = 0;
|
|
|
|
return kobj;
|
|
}
|
|
|
|
static int __init brd_init(void)
|
|
{
|
|
struct brd_device *brd, *next;
|
|
int i;
|
|
|
|
/*
|
|
* brd module now has a feature to instantiate underlying device
|
|
* structure on-demand, provided that there is an access dev node.
|
|
*
|
|
* (1) if rd_nr is specified, create that many upfront. else
|
|
* it defaults to CONFIG_BLK_DEV_RAM_COUNT
|
|
* (2) User can further extend brd devices by create dev node themselves
|
|
* and have kernel automatically instantiate actual device
|
|
* on-demand. Example:
|
|
* mknod /path/devnod_name b 1 X # 1 is the rd major
|
|
* fdisk -l /path/devnod_name
|
|
* If (X / max_part) was not already created it will be created
|
|
* dynamically.
|
|
*/
|
|
|
|
if (register_blkdev(RAMDISK_MAJOR, "ramdisk"))
|
|
return -EIO;
|
|
|
|
if (unlikely(!max_part))
|
|
max_part = 1;
|
|
|
|
for (i = 0; i < rd_nr; i++) {
|
|
brd = brd_alloc(i);
|
|
if (!brd)
|
|
goto out_free;
|
|
list_add_tail(&brd->brd_list, &brd_devices);
|
|
}
|
|
|
|
/* point of no return */
|
|
|
|
list_for_each_entry(brd, &brd_devices, brd_list)
|
|
add_disk(brd->brd_disk);
|
|
|
|
blk_register_region(MKDEV(RAMDISK_MAJOR, 0), 1UL << MINORBITS,
|
|
THIS_MODULE, brd_probe, NULL, NULL);
|
|
|
|
pr_info("brd: module loaded\n");
|
|
return 0;
|
|
|
|
out_free:
|
|
list_for_each_entry_safe(brd, next, &brd_devices, brd_list) {
|
|
list_del(&brd->brd_list);
|
|
brd_free(brd);
|
|
}
|
|
unregister_blkdev(RAMDISK_MAJOR, "ramdisk");
|
|
|
|
pr_info("brd: module NOT loaded !!!\n");
|
|
return -ENOMEM;
|
|
}
|
|
|
|
static void __exit brd_exit(void)
|
|
{
|
|
struct brd_device *brd, *next;
|
|
|
|
list_for_each_entry_safe(brd, next, &brd_devices, brd_list)
|
|
brd_del_one(brd);
|
|
|
|
blk_unregister_region(MKDEV(RAMDISK_MAJOR, 0), 1UL << MINORBITS);
|
|
unregister_blkdev(RAMDISK_MAJOR, "ramdisk");
|
|
|
|
pr_info("brd: module unloaded\n");
|
|
}
|
|
|
|
module_init(brd_init);
|
|
module_exit(brd_exit);
|
|
|