dax: fix lifetime of in-kernel dax mappings with dax_map_atomic() (b2e0d162) · Commits · 戴 / test

fs/block_dev.c

+5 −8

Original line number	Diff line number	Diff line
		@@ -455,10 +455,7 @@ EXPORT_SYMBOL_GPL(bdev_write_page);
		/**
		* bdev_direct_access() - Get the address for directly-accessibly memory
		* @bdev: The device containing the memory
		* @sector: The offset within the device
		* @addr: Where to put the address of the memory
		* @pfn: The Page Frame Number for the memory
		* @size: The number of bytes requested
		* @dax: control and output parameters for ->direct_access
		*
		* If a block device is made up of directly addressable memory, this function
		* will tell the caller the PFN and the address of the memory. The address
		@@ -469,10 +466,10 @@ EXPORT_SYMBOL_GPL(bdev_write_page);
		* Return: negative errno if an error occurs, otherwise the number of bytes
		* accessible at this address.
		*/
		long bdev_direct_access(struct block_device *bdev, sector_t sector,
		void __pmem *addr, unsigned long pfn, long size)
		long bdev_direct_access(struct block_device bdev, struct blk_dax_ctl dax)
		{
		long avail;
		sector_t sector = dax->sector;
		long avail, size = dax->size;
		const struct block_device_operations *ops = bdev->bd_disk->fops;

		/*
		@@ -491,7 +488,7 @@ long bdev_direct_access(struct block_device *bdev, sector_t sector,
		sector += get_start_sect(bdev);
		if (sector % (PAGE_SIZE / 512))
		return -EINVAL;
		avail = ops->direct_access(bdev, sector, addr, pfn);
		avail = ops->direct_access(bdev, sector, &dax->addr, &dax->pfn);
		if (!avail)
		return -ERANGE;
		if (avail > 0 && avail & ~PAGE_MASK)

fs/dax.c

+130 −78

Original line number	Diff line number	Diff line
		@@ -30,45 +30,65 @@
		#include <linux/vmstat.h>
		#include <linux/sizes.h>

		static long dax_map_atomic(struct block_device bdev, struct blk_dax_ctl dax)
		{
		struct request_queue *q = bdev->bd_queue;
		long rc = -EIO;

		dax->addr = (void __pmem *) ERR_PTR(-EIO);
		if (blk_queue_enter(q, true) != 0)
		return rc;

		rc = bdev_direct_access(bdev, dax);
		if (rc < 0) {
		dax->addr = (void __pmem *) ERR_PTR(rc);
		blk_queue_exit(q);
		return rc;
		}
		return rc;
		}

		static void dax_unmap_atomic(struct block_device *bdev,
		const struct blk_dax_ctl *dax)
		{
		if (IS_ERR(dax->addr))
		return;
		blk_queue_exit(bdev->bd_queue);
		}

		/*
		* dax_clear_blocks() is called from within transaction context from XFS,
		* and hence this means the stack from this point must follow GFP_NOFS
		* semantics for all operations.
		*/
		int dax_clear_blocks(struct inode *inode, sector_t block, long size)
		int dax_clear_blocks(struct inode *inode, sector_t block, long _size)
		{
		struct block_device *bdev = inode->i_sb->s_bdev;
		sector_t sector = block << (inode->i_blkbits - 9);
		struct blk_dax_ctl dax = {
		.sector = block << (inode->i_blkbits - 9),
		.size = _size,
		};

		might_sleep();
		do {
		void __pmem *addr;
		unsigned long pfn;
		long count, sz;

		count = bdev_direct_access(bdev, sector, &addr, &pfn, size);
		count = dax_map_atomic(bdev, &dax);
		if (count < 0)
		return count;
		sz = min_t(long, count, SZ_128K);
		clear_pmem(addr, sz);
		size -= sz;
		sector += sz / 512;
		clear_pmem(dax.addr, sz);
		dax.size -= sz;
		dax.sector += sz / 512;
		dax_unmap_atomic(bdev, &dax);
		cond_resched();
		} while (size);
		} while (dax.size);

		wmb_pmem();
		return 0;
		}
		EXPORT_SYMBOL_GPL(dax_clear_blocks);

		static long dax_get_addr(struct buffer_head bh, void __pmem *addr,
		unsigned blkbits)
		{
		unsigned long pfn;
		sector_t sector = bh->b_blocknr << (blkbits - 9);
		return bdev_direct_access(bh->b_bdev, sector, addr, &pfn, bh->b_size);
		}

		/* the clear_pmem() calls are ordered by a wmb_pmem() in the caller */
		static void dax_new_buf(void __pmem *addr, unsigned size, unsigned first,
		loff_t pos, loff_t end)
		@@ -98,19 +118,29 @@ static bool buffer_size_valid(struct buffer_head *bh)
		return bh->b_state != 0;
		}


		static sector_t to_sector(const struct buffer_head *bh,
		const struct inode *inode)
		{
		sector_t sector = bh->b_blocknr << (inode->i_blkbits - 9);

		return sector;
		}

		static ssize_t dax_io(struct inode inode, struct iov_iter iter,
		loff_t start, loff_t end, get_block_t get_block,
		struct buffer_head *bh)
		{
		ssize_t retval = 0;
		loff_t pos = start;
		loff_t max = start;
		loff_t bh_max = start;
		void __pmem *addr;
		bool hole = false;
		bool need_wmb = false;

		if (iov_iter_rw(iter) != WRITE)
		loff_t pos = start, max = start, bh_max = start;
		bool hole = false, need_wmb = false;
		struct block_device *bdev = NULL;
		int rw = iov_iter_rw(iter), rc;
		long map_len = 0;
		struct blk_dax_ctl dax = {
		.addr = (void __pmem *) ERR_PTR(-EIO),
		};

		if (rw == READ)
		end = min(end, i_size_read(inode));

		while (pos < end) {
		@@ -125,13 +155,13 @@ static ssize_t dax_io(struct inode inode, struct iov_iter iter,
		if (pos == bh_max) {
		bh->b_size = PAGE_ALIGN(end - pos);
		bh->b_state = 0;
		retval = get_block(inode, block, bh,
		iov_iter_rw(iter) == WRITE);
		if (retval)
		rc = get_block(inode, block, bh, rw == WRITE);
		if (rc)
		break;
		if (!buffer_size_valid(bh))
		bh->b_size = 1 << blkbits;
		bh_max = pos - first + bh->b_size;
		bdev = bh->b_bdev;
		} else {
		unsigned done = bh->b_size -
		(bh_max - (pos - first));
		@@ -139,47 +169,53 @@ static ssize_t dax_io(struct inode inode, struct iov_iter iter,
		bh->b_size -= done;
		}

		hole = iov_iter_rw(iter) != WRITE && !buffer_written(bh);
		hole = rw == READ && !buffer_written(bh);
		if (hole) {
		addr = NULL;
		size = bh->b_size - first;
		} else {
		retval = dax_get_addr(bh, &addr, blkbits);
		if (retval < 0)
		dax_unmap_atomic(bdev, &dax);
		dax.sector = to_sector(bh, inode);
		dax.size = bh->b_size;
		map_len = dax_map_atomic(bdev, &dax);
		if (map_len < 0) {
		rc = map_len;
		break;
		}
		if (buffer_unwritten(bh) \|\| buffer_new(bh)) {
		dax_new_buf(addr, retval, first, pos,
		end);
		dax_new_buf(dax.addr, map_len, first,
		pos, end);
		need_wmb = true;
		}
		addr += first;
		size = retval - first;
		dax.addr += first;
		size = map_len - first;
		}
		max = min(pos + size, end);
		}

		if (iov_iter_rw(iter) == WRITE) {
		len = copy_from_iter_pmem(addr, max - pos, iter);
		len = copy_from_iter_pmem(dax.addr, max - pos, iter);
		need_wmb = true;
		} else if (!hole)
		len = copy_to_iter((void __force *)addr, max - pos,
		len = copy_to_iter((void __force *) dax.addr, max - pos,
		iter);
		else
		len = iov_iter_zero(max - pos, iter);

		if (!len) {
		retval = -EFAULT;
		rc = -EFAULT;
		break;
		}

		pos += len;
		addr += len;
		if (!IS_ERR(dax.addr))
		dax.addr += len;
		}

		if (need_wmb)
		wmb_pmem();
		dax_unmap_atomic(bdev, &dax);

		return (pos == start) ? retval : pos - start;
		return (pos == start) ? rc : pos - start;
		}

		/**
		@@ -268,28 +304,35 @@ static int dax_load_hole(struct address_space mapping, struct page page,
		return VM_FAULT_LOCKED;
		}

		static int copy_user_bh(struct page to, struct buffer_head bh,
		unsigned blkbits, unsigned long vaddr)
		static int copy_user_bh(struct page to, struct inode inode,
		struct buffer_head *bh, unsigned long vaddr)
		{
		void __pmem *vfrom;
		struct blk_dax_ctl dax = {
		.sector = to_sector(bh, inode),
		.size = bh->b_size,
		};
		struct block_device *bdev = bh->b_bdev;
		void *vto;

		if (dax_get_addr(bh, &vfrom, blkbits) < 0)
		return -EIO;
		if (dax_map_atomic(bdev, &dax) < 0)
		return PTR_ERR(dax.addr);
		vto = kmap_atomic(to);
		copy_user_page(vto, (void __force *)vfrom, vaddr, to);
		copy_user_page(vto, (void __force *)dax.addr, vaddr, to);
		kunmap_atomic(vto);
		dax_unmap_atomic(bdev, &dax);
		return 0;
		}

		static int dax_insert_mapping(struct inode inode, struct buffer_head bh,
		struct vm_area_struct vma, struct vm_fault vmf)
		{
		struct address_space *mapping = inode->i_mapping;
		sector_t sector = bh->b_blocknr << (inode->i_blkbits - 9);
		unsigned long vaddr = (unsigned long)vmf->virtual_address;
		void __pmem *addr;
		unsigned long pfn;
		struct address_space *mapping = inode->i_mapping;
		struct block_device *bdev = bh->b_bdev;
		struct blk_dax_ctl dax = {
		.sector = to_sector(bh, inode),
		.size = bh->b_size,
		};
		pgoff_t size;
		int error;

		@@ -308,20 +351,18 @@ static int dax_insert_mapping(struct inode inode, struct buffer_head bh,
		goto out;
		}

		error = bdev_direct_access(bh->b_bdev, sector, &addr, &pfn, bh->b_size);
		if (error < 0)
		goto out;
		if (error < PAGE_SIZE) {
		error = -EIO;
		if (dax_map_atomic(bdev, &dax) < 0) {
		error = PTR_ERR(dax.addr);
		goto out;
		}

		if (buffer_unwritten(bh) \|\| buffer_new(bh)) {
		clear_pmem(addr, PAGE_SIZE);
		clear_pmem(dax.addr, PAGE_SIZE);
		wmb_pmem();
		}
		dax_unmap_atomic(bdev, &dax);

		error = vm_insert_mixed(vma, vaddr, pfn);
		error = vm_insert_mixed(vma, vaddr, dax.pfn);

		out:
		i_mmap_unlock_read(mapping);
		@@ -415,7 +456,7 @@ int __dax_fault(struct vm_area_struct vma, struct vm_fault vmf,
		if (vmf->cow_page) {
		struct page *new_page = vmf->cow_page;
		if (buffer_written(&bh))
		error = copy_user_bh(new_page, &bh, blkbits, vaddr);
		error = copy_user_bh(new_page, inode, &bh, vaddr);
		else
		clear_user_highpage(new_page, vaddr);
		if (error)
		@@ -527,11 +568,9 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
		unsigned blkbits = inode->i_blkbits;
		unsigned long pmd_addr = address & PMD_MASK;
		bool write = flags & FAULT_FLAG_WRITE;
		long length;
		void __pmem *kaddr;
		struct block_device *bdev;
		pgoff_t size, pgoff;
		sector_t block, sector;
		unsigned long pfn;
		sector_t block;
		int result = 0;

		/* dax pmd mappings are broken wrt gup and fork */
		@@ -559,9 +598,9 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
		block = (sector_t)pgoff << (PAGE_SHIFT - blkbits);

		bh.b_size = PMD_SIZE;
		length = get_block(inode, block, &bh, write);
		if (length)
		if (get_block(inode, block, &bh, write) != 0)
		return VM_FAULT_SIGBUS;
		bdev = bh.b_bdev;
		i_mmap_lock_read(mapping);

		/*
		@@ -616,32 +655,40 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
		result = VM_FAULT_NOPAGE;
		spin_unlock(ptl);
		} else {
		sector = bh.b_blocknr << (blkbits - 9);
		length = bdev_direct_access(bh.b_bdev, sector, &kaddr, &pfn,
		bh.b_size);
		struct blk_dax_ctl dax = {
		.sector = to_sector(&bh, inode),
		.size = PMD_SIZE,
		};
		long length = dax_map_atomic(bdev, &dax);

		if (length < 0) {
		result = VM_FAULT_SIGBUS;
		goto out;
		}
		if ((length < PMD_SIZE) \|\| (pfn & PG_PMD_COLOUR))
		if ((length < PMD_SIZE) \|\| (dax.pfn & PG_PMD_COLOUR)) {
		dax_unmap_atomic(bdev, &dax);
		goto fallback;
		}

		/*
		* TODO: teach vmf_insert_pfn_pmd() to support
		* 'pte_special' for pmds
		*/
		if (pfn_valid(pfn))
		if (pfn_valid(dax.pfn)) {
		dax_unmap_atomic(bdev, &dax);
		goto fallback;
		}

		if (buffer_unwritten(&bh) \|\| buffer_new(&bh)) {
		clear_pmem(kaddr, PMD_SIZE);
		clear_pmem(dax.addr, PMD_SIZE);
		wmb_pmem();
		count_vm_event(PGMAJFAULT);
		mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT);
		result \|= VM_FAULT_MAJOR;
		}
		dax_unmap_atomic(bdev, &dax);

		result \|= vmf_insert_pfn_pmd(vma, address, pmd, pfn, write);
		result \|= vmf_insert_pfn_pmd(vma, address, pmd, dax.pfn, write);
		}

		out:
		@@ -743,12 +790,17 @@ int dax_zero_page_range(struct inode *inode, loff_t from, unsigned length,
		if (err < 0)
		return err;
		if (buffer_written(&bh)) {
		void __pmem *addr;
		err = dax_get_addr(&bh, &addr, inode->i_blkbits);
		if (err < 0)
		return err;
		clear_pmem(addr + offset, length);
		struct block_device *bdev = bh.b_bdev;
		struct blk_dax_ctl dax = {
		.sector = to_sector(&bh, inode),
		.size = PAGE_CACHE_SIZE,
		};

		if (dax_map_atomic(bdev, &dax) < 0)
		return PTR_ERR(dax.addr);
		clear_pmem(dax.addr + offset, length);
		wmb_pmem();
		dax_unmap_atomic(bdev, &dax);
		}

		return 0;

include/linux/blkdev.h

+15 −2

Original line number	Diff line number	Diff line
		@@ -1617,6 +1617,20 @@ static inline bool integrity_req_gap_front_merge(struct request *req,

		#endif /* CONFIG_BLK_DEV_INTEGRITY */

		/**
		* struct blk_dax_ctl - control and output parameters for ->direct_access
		* @sector: (input) offset relative to a block_device
		* @addr: (output) kernel virtual address for @sector populated by driver
		* @pfn: (output) page frame number for @addr populated by driver
		* @size: (input) number of bytes requested
		*/
		struct blk_dax_ctl {
		sector_t sector;
		void __pmem *addr;
		long size;
		unsigned long pfn;
		};

		struct block_device_operations {
		int (open) (struct block_device , fmode_t);
		void (release) (struct gendisk , fmode_t);
		@@ -1643,8 +1657,7 @@ extern int __blkdev_driver_ioctl(struct block_device *, fmode_t, unsigned int,
		extern int bdev_read_page(struct block_device , sector_t, struct page );
		extern int bdev_write_page(struct block_device , sector_t, struct page ,
		struct writeback_control *);
		extern long bdev_direct_access(struct block_device *, sector_t,
		void __pmem *addr, unsigned long pfn, long size);
		extern long bdev_direct_access(struct block_device , struct blk_dax_ctl );
		#else /* CONFIG_BLOCK */

		struct block_device;

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