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287f3ca563
The global variable 'rd_size' is declared as 'int' in source file arch/arm/kernel/atags_parse.c and as 'unsigned long' in drivers/block/brd.c. Fix this inconsistency. Additionally, remove the declarations of rd_image_start, rd_prompt and rd_doload from parse_tag_ramdisk() since these duplicate existing declarations in <linux/initrd.h>. Link: http://lkml.kernel.org/r/20170627065024.12347-1-bart.vanassche@wdc.com Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com> Acked-by: Russell King <rmk+kernel@armlinux.org.uk> Cc: Jens Axboe <axboe@kernel.dk> Cc: Jan Kara <jack@suse.cz> Cc: Jason Yan <yanaijie@huawei.com> Cc: Zhaohongjiang <zhaohongjiang@huawei.com> Cc: Miao Xie <miaoxie@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
600 lines
14 KiB
C
600 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 block_device *bdev = bio->bi_bdev;
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struct brd_device *brd = bdev->bd_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(bdev->bd_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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}
|
|
*new = true;
|
|
out:
|
|
return brd;
|
|
}
|
|
|
|
static void brd_del_one(struct brd_device *brd)
|
|
{
|
|
list_del(&brd->brd_list);
|
|
#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);
|
|
|