1147 строки
32 KiB
C
1147 строки
32 KiB
C
/*
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* fs/dax.c - Direct Access filesystem code
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* Copyright (c) 2013-2014 Intel Corporation
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* Author: Matthew Wilcox <matthew.r.wilcox@intel.com>
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* Author: Ross Zwisler <ross.zwisler@linux.intel.com>
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms and conditions of the GNU General Public License,
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* version 2, as published by the Free Software Foundation.
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*
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* This program is distributed in the hope it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*/
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#include <linux/atomic.h>
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#include <linux/blkdev.h>
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#include <linux/buffer_head.h>
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#include <linux/dax.h>
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#include <linux/fs.h>
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#include <linux/genhd.h>
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#include <linux/highmem.h>
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#include <linux/memcontrol.h>
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#include <linux/mm.h>
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#include <linux/mutex.h>
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#include <linux/pagevec.h>
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#include <linux/pmem.h>
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#include <linux/sched.h>
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#include <linux/uio.h>
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#include <linux/vmstat.h>
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#include <linux/pfn_t.h>
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#include <linux/sizes.h>
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static long dax_map_atomic(struct block_device *bdev, struct blk_dax_ctl *dax)
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{
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struct request_queue *q = bdev->bd_queue;
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long rc = -EIO;
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dax->addr = (void __pmem *) ERR_PTR(-EIO);
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if (blk_queue_enter(q, true) != 0)
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return rc;
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rc = bdev_direct_access(bdev, dax);
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if (rc < 0) {
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dax->addr = (void __pmem *) ERR_PTR(rc);
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blk_queue_exit(q);
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return rc;
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}
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return rc;
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}
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static void dax_unmap_atomic(struct block_device *bdev,
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const struct blk_dax_ctl *dax)
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{
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if (IS_ERR(dax->addr))
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return;
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blk_queue_exit(bdev->bd_queue);
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}
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struct page *read_dax_sector(struct block_device *bdev, sector_t n)
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{
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struct page *page = alloc_pages(GFP_KERNEL, 0);
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struct blk_dax_ctl dax = {
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.size = PAGE_SIZE,
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.sector = n & ~((((int) PAGE_SIZE) / 512) - 1),
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};
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long rc;
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if (!page)
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return ERR_PTR(-ENOMEM);
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rc = dax_map_atomic(bdev, &dax);
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if (rc < 0)
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return ERR_PTR(rc);
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memcpy_from_pmem(page_address(page), dax.addr, PAGE_SIZE);
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dax_unmap_atomic(bdev, &dax);
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return page;
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}
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/*
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* dax_clear_blocks() is called from within transaction context from XFS,
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* and hence this means the stack from this point must follow GFP_NOFS
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* semantics for all operations.
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*/
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int dax_clear_blocks(struct inode *inode, sector_t block, long _size)
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{
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struct block_device *bdev = inode->i_sb->s_bdev;
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struct blk_dax_ctl dax = {
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.sector = block << (inode->i_blkbits - 9),
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.size = _size,
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};
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might_sleep();
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do {
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long count, sz;
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count = dax_map_atomic(bdev, &dax);
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if (count < 0)
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return count;
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sz = min_t(long, count, SZ_128K);
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clear_pmem(dax.addr, sz);
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dax.size -= sz;
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dax.sector += sz / 512;
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dax_unmap_atomic(bdev, &dax);
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cond_resched();
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} while (dax.size);
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wmb_pmem();
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return 0;
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}
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EXPORT_SYMBOL_GPL(dax_clear_blocks);
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/* the clear_pmem() calls are ordered by a wmb_pmem() in the caller */
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static void dax_new_buf(void __pmem *addr, unsigned size, unsigned first,
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loff_t pos, loff_t end)
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{
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loff_t final = end - pos + first; /* The final byte of the buffer */
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if (first > 0)
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clear_pmem(addr, first);
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if (final < size)
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clear_pmem(addr + final, size - final);
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}
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static bool buffer_written(struct buffer_head *bh)
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{
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return buffer_mapped(bh) && !buffer_unwritten(bh);
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}
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/*
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* When ext4 encounters a hole, it returns without modifying the buffer_head
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* which means that we can't trust b_size. To cope with this, we set b_state
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* to 0 before calling get_block and, if any bit is set, we know we can trust
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* b_size. Unfortunate, really, since ext4 knows precisely how long a hole is
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* and would save us time calling get_block repeatedly.
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*/
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static bool buffer_size_valid(struct buffer_head *bh)
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{
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return bh->b_state != 0;
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}
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static sector_t to_sector(const struct buffer_head *bh,
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const struct inode *inode)
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{
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sector_t sector = bh->b_blocknr << (inode->i_blkbits - 9);
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return sector;
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}
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static ssize_t dax_io(struct inode *inode, struct iov_iter *iter,
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loff_t start, loff_t end, get_block_t get_block,
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struct buffer_head *bh)
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{
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loff_t pos = start, max = start, bh_max = start;
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bool hole = false, need_wmb = false;
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struct block_device *bdev = NULL;
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int rw = iov_iter_rw(iter), rc;
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long map_len = 0;
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struct blk_dax_ctl dax = {
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.addr = (void __pmem *) ERR_PTR(-EIO),
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};
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if (rw == READ)
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end = min(end, i_size_read(inode));
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while (pos < end) {
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size_t len;
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if (pos == max) {
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unsigned blkbits = inode->i_blkbits;
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long page = pos >> PAGE_SHIFT;
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sector_t block = page << (PAGE_SHIFT - blkbits);
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unsigned first = pos - (block << blkbits);
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long size;
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if (pos == bh_max) {
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bh->b_size = PAGE_ALIGN(end - pos);
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bh->b_state = 0;
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rc = get_block(inode, block, bh, rw == WRITE);
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if (rc)
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break;
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if (!buffer_size_valid(bh))
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bh->b_size = 1 << blkbits;
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bh_max = pos - first + bh->b_size;
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bdev = bh->b_bdev;
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} else {
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unsigned done = bh->b_size -
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(bh_max - (pos - first));
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bh->b_blocknr += done >> blkbits;
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bh->b_size -= done;
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}
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hole = rw == READ && !buffer_written(bh);
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if (hole) {
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size = bh->b_size - first;
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} else {
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dax_unmap_atomic(bdev, &dax);
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dax.sector = to_sector(bh, inode);
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dax.size = bh->b_size;
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map_len = dax_map_atomic(bdev, &dax);
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if (map_len < 0) {
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rc = map_len;
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break;
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}
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if (buffer_unwritten(bh) || buffer_new(bh)) {
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dax_new_buf(dax.addr, map_len, first,
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pos, end);
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need_wmb = true;
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}
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dax.addr += first;
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size = map_len - first;
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}
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max = min(pos + size, end);
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}
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if (iov_iter_rw(iter) == WRITE) {
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len = copy_from_iter_pmem(dax.addr, max - pos, iter);
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need_wmb = true;
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} else if (!hole)
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len = copy_to_iter((void __force *) dax.addr, max - pos,
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iter);
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else
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len = iov_iter_zero(max - pos, iter);
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if (!len) {
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rc = -EFAULT;
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break;
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}
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pos += len;
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if (!IS_ERR(dax.addr))
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dax.addr += len;
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}
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if (need_wmb)
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wmb_pmem();
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dax_unmap_atomic(bdev, &dax);
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return (pos == start) ? rc : pos - start;
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}
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/**
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* dax_do_io - Perform I/O to a DAX file
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* @iocb: The control block for this I/O
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* @inode: The file which the I/O is directed at
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* @iter: The addresses to do I/O from or to
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* @pos: The file offset where the I/O starts
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* @get_block: The filesystem method used to translate file offsets to blocks
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* @end_io: A filesystem callback for I/O completion
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* @flags: See below
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*
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* This function uses the same locking scheme as do_blockdev_direct_IO:
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* If @flags has DIO_LOCKING set, we assume that the i_mutex is held by the
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* caller for writes. For reads, we take and release the i_mutex ourselves.
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* If DIO_LOCKING is not set, the filesystem takes care of its own locking.
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* As with do_blockdev_direct_IO(), we increment i_dio_count while the I/O
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* is in progress.
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*/
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ssize_t dax_do_io(struct kiocb *iocb, struct inode *inode,
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struct iov_iter *iter, loff_t pos, get_block_t get_block,
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dio_iodone_t end_io, int flags)
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{
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struct buffer_head bh;
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ssize_t retval = -EINVAL;
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loff_t end = pos + iov_iter_count(iter);
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memset(&bh, 0, sizeof(bh));
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bh.b_bdev = inode->i_sb->s_bdev;
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if ((flags & DIO_LOCKING) && iov_iter_rw(iter) == READ) {
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struct address_space *mapping = inode->i_mapping;
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inode_lock(inode);
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retval = filemap_write_and_wait_range(mapping, pos, end - 1);
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if (retval) {
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inode_unlock(inode);
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goto out;
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}
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}
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/* Protects against truncate */
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if (!(flags & DIO_SKIP_DIO_COUNT))
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inode_dio_begin(inode);
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retval = dax_io(inode, iter, pos, end, get_block, &bh);
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if ((flags & DIO_LOCKING) && iov_iter_rw(iter) == READ)
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inode_unlock(inode);
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if ((retval > 0) && end_io)
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end_io(iocb, pos, retval, bh.b_private);
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if (!(flags & DIO_SKIP_DIO_COUNT))
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inode_dio_end(inode);
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out:
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return retval;
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}
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EXPORT_SYMBOL_GPL(dax_do_io);
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/*
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* The user has performed a load from a hole in the file. Allocating
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* a new page in the file would cause excessive storage usage for
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* workloads with sparse files. We allocate a page cache page instead.
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* We'll kick it out of the page cache if it's ever written to,
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* otherwise it will simply fall out of the page cache under memory
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* pressure without ever having been dirtied.
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*/
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static int dax_load_hole(struct address_space *mapping, struct page *page,
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struct vm_fault *vmf)
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{
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unsigned long size;
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struct inode *inode = mapping->host;
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if (!page)
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page = find_or_create_page(mapping, vmf->pgoff,
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GFP_KERNEL | __GFP_ZERO);
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if (!page)
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return VM_FAULT_OOM;
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/* Recheck i_size under page lock to avoid truncate race */
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size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT;
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if (vmf->pgoff >= size) {
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unlock_page(page);
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page_cache_release(page);
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return VM_FAULT_SIGBUS;
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}
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vmf->page = page;
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return VM_FAULT_LOCKED;
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}
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static int copy_user_bh(struct page *to, struct inode *inode,
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struct buffer_head *bh, unsigned long vaddr)
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{
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struct blk_dax_ctl dax = {
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.sector = to_sector(bh, inode),
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.size = bh->b_size,
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};
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struct block_device *bdev = bh->b_bdev;
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void *vto;
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if (dax_map_atomic(bdev, &dax) < 0)
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return PTR_ERR(dax.addr);
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vto = kmap_atomic(to);
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copy_user_page(vto, (void __force *)dax.addr, vaddr, to);
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kunmap_atomic(vto);
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dax_unmap_atomic(bdev, &dax);
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return 0;
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}
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#define NO_SECTOR -1
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#define DAX_PMD_INDEX(page_index) (page_index & (PMD_MASK >> PAGE_CACHE_SHIFT))
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static int dax_radix_entry(struct address_space *mapping, pgoff_t index,
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sector_t sector, bool pmd_entry, bool dirty)
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{
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struct radix_tree_root *page_tree = &mapping->page_tree;
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pgoff_t pmd_index = DAX_PMD_INDEX(index);
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int type, error = 0;
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void *entry;
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WARN_ON_ONCE(pmd_entry && !dirty);
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__mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
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spin_lock_irq(&mapping->tree_lock);
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entry = radix_tree_lookup(page_tree, pmd_index);
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if (entry && RADIX_DAX_TYPE(entry) == RADIX_DAX_PMD) {
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index = pmd_index;
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goto dirty;
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}
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entry = radix_tree_lookup(page_tree, index);
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if (entry) {
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type = RADIX_DAX_TYPE(entry);
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if (WARN_ON_ONCE(type != RADIX_DAX_PTE &&
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type != RADIX_DAX_PMD)) {
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error = -EIO;
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goto unlock;
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}
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if (!pmd_entry || type == RADIX_DAX_PMD)
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goto dirty;
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/*
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* We only insert dirty PMD entries into the radix tree. This
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* means we don't need to worry about removing a dirty PTE
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* entry and inserting a clean PMD entry, thus reducing the
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* range we would flush with a follow-up fsync/msync call.
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*/
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radix_tree_delete(&mapping->page_tree, index);
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mapping->nrexceptional--;
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}
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if (sector == NO_SECTOR) {
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/*
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* This can happen during correct operation if our pfn_mkwrite
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* fault raced against a hole punch operation. If this
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* happens the pte that was hole punched will have been
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* unmapped and the radix tree entry will have been removed by
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* the time we are called, but the call will still happen. We
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* will return all the way up to wp_pfn_shared(), where the
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* pte_same() check will fail, eventually causing page fault
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* to be retried by the CPU.
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*/
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goto unlock;
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}
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error = radix_tree_insert(page_tree, index,
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RADIX_DAX_ENTRY(sector, pmd_entry));
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if (error)
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goto unlock;
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mapping->nrexceptional++;
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dirty:
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if (dirty)
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radix_tree_tag_set(page_tree, index, PAGECACHE_TAG_DIRTY);
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unlock:
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spin_unlock_irq(&mapping->tree_lock);
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return error;
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}
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static int dax_writeback_one(struct block_device *bdev,
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struct address_space *mapping, pgoff_t index, void *entry)
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{
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struct radix_tree_root *page_tree = &mapping->page_tree;
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int type = RADIX_DAX_TYPE(entry);
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struct radix_tree_node *node;
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struct blk_dax_ctl dax;
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void **slot;
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int ret = 0;
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spin_lock_irq(&mapping->tree_lock);
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/*
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* Regular page slots are stabilized by the page lock even
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* without the tree itself locked. These unlocked entries
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* need verification under the tree lock.
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*/
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if (!__radix_tree_lookup(page_tree, index, &node, &slot))
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goto unlock;
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if (*slot != entry)
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goto unlock;
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/* another fsync thread may have already written back this entry */
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if (!radix_tree_tag_get(page_tree, index, PAGECACHE_TAG_TOWRITE))
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goto unlock;
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if (WARN_ON_ONCE(type != RADIX_DAX_PTE && type != RADIX_DAX_PMD)) {
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ret = -EIO;
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goto unlock;
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}
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dax.sector = RADIX_DAX_SECTOR(entry);
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dax.size = (type == RADIX_DAX_PMD ? PMD_SIZE : PAGE_SIZE);
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spin_unlock_irq(&mapping->tree_lock);
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/*
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* We cannot hold tree_lock while calling dax_map_atomic() because it
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* eventually calls cond_resched().
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*/
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ret = dax_map_atomic(bdev, &dax);
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if (ret < 0)
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return ret;
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if (WARN_ON_ONCE(ret < dax.size)) {
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ret = -EIO;
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goto unmap;
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}
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wb_cache_pmem(dax.addr, dax.size);
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spin_lock_irq(&mapping->tree_lock);
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radix_tree_tag_clear(page_tree, index, PAGECACHE_TAG_TOWRITE);
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spin_unlock_irq(&mapping->tree_lock);
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unmap:
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dax_unmap_atomic(bdev, &dax);
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return ret;
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unlock:
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spin_unlock_irq(&mapping->tree_lock);
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return ret;
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}
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|
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/*
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* Flush the mapping to the persistent domain within the byte range of [start,
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* end]. This is required by data integrity operations to ensure file data is
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* on persistent storage prior to completion of the operation.
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*/
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int dax_writeback_mapping_range(struct address_space *mapping, loff_t start,
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loff_t end)
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{
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struct inode *inode = mapping->host;
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struct block_device *bdev = inode->i_sb->s_bdev;
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pgoff_t start_index, end_index, pmd_index;
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pgoff_t indices[PAGEVEC_SIZE];
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struct pagevec pvec;
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bool done = false;
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int i, ret = 0;
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void *entry;
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|
|
if (WARN_ON_ONCE(inode->i_blkbits != PAGE_SHIFT))
|
|
return -EIO;
|
|
|
|
start_index = start >> PAGE_CACHE_SHIFT;
|
|
end_index = end >> PAGE_CACHE_SHIFT;
|
|
pmd_index = DAX_PMD_INDEX(start_index);
|
|
|
|
rcu_read_lock();
|
|
entry = radix_tree_lookup(&mapping->page_tree, pmd_index);
|
|
rcu_read_unlock();
|
|
|
|
/* see if the start of our range is covered by a PMD entry */
|
|
if (entry && RADIX_DAX_TYPE(entry) == RADIX_DAX_PMD)
|
|
start_index = pmd_index;
|
|
|
|
tag_pages_for_writeback(mapping, start_index, end_index);
|
|
|
|
pagevec_init(&pvec, 0);
|
|
while (!done) {
|
|
pvec.nr = find_get_entries_tag(mapping, start_index,
|
|
PAGECACHE_TAG_TOWRITE, PAGEVEC_SIZE,
|
|
pvec.pages, indices);
|
|
|
|
if (pvec.nr == 0)
|
|
break;
|
|
|
|
for (i = 0; i < pvec.nr; i++) {
|
|
if (indices[i] > end_index) {
|
|
done = true;
|
|
break;
|
|
}
|
|
|
|
ret = dax_writeback_one(bdev, mapping, indices[i],
|
|
pvec.pages[i]);
|
|
if (ret < 0)
|
|
return ret;
|
|
}
|
|
}
|
|
wmb_pmem();
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(dax_writeback_mapping_range);
|
|
|
|
static int dax_insert_mapping(struct inode *inode, struct buffer_head *bh,
|
|
struct vm_area_struct *vma, struct vm_fault *vmf)
|
|
{
|
|
unsigned long vaddr = (unsigned long)vmf->virtual_address;
|
|
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;
|
|
|
|
i_mmap_lock_read(mapping);
|
|
|
|
/*
|
|
* Check truncate didn't happen while we were allocating a block.
|
|
* If it did, this block may or may not be still allocated to the
|
|
* file. We can't tell the filesystem to free it because we can't
|
|
* take i_mutex here. In the worst case, the file still has blocks
|
|
* allocated past the end of the file.
|
|
*/
|
|
size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT;
|
|
if (unlikely(vmf->pgoff >= size)) {
|
|
error = -EIO;
|
|
goto out;
|
|
}
|
|
|
|
if (dax_map_atomic(bdev, &dax) < 0) {
|
|
error = PTR_ERR(dax.addr);
|
|
goto out;
|
|
}
|
|
|
|
if (buffer_unwritten(bh) || buffer_new(bh)) {
|
|
clear_pmem(dax.addr, PAGE_SIZE);
|
|
wmb_pmem();
|
|
}
|
|
dax_unmap_atomic(bdev, &dax);
|
|
|
|
error = dax_radix_entry(mapping, vmf->pgoff, dax.sector, false,
|
|
vmf->flags & FAULT_FLAG_WRITE);
|
|
if (error)
|
|
goto out;
|
|
|
|
error = vm_insert_mixed(vma, vaddr, dax.pfn);
|
|
|
|
out:
|
|
i_mmap_unlock_read(mapping);
|
|
|
|
return error;
|
|
}
|
|
|
|
/**
|
|
* __dax_fault - handle a page fault on a DAX file
|
|
* @vma: The virtual memory area where the fault occurred
|
|
* @vmf: The description of the fault
|
|
* @get_block: The filesystem method used to translate file offsets to blocks
|
|
* @complete_unwritten: The filesystem method used to convert unwritten blocks
|
|
* to written so the data written to them is exposed. This is required for
|
|
* required by write faults for filesystems that will return unwritten
|
|
* extent mappings from @get_block, but it is optional for reads as
|
|
* dax_insert_mapping() will always zero unwritten blocks. If the fs does
|
|
* not support unwritten extents, the it should pass NULL.
|
|
*
|
|
* When a page fault occurs, filesystems may call this helper in their
|
|
* fault handler for DAX files. __dax_fault() assumes the caller has done all
|
|
* the necessary locking for the page fault to proceed successfully.
|
|
*/
|
|
int __dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
|
|
get_block_t get_block, dax_iodone_t complete_unwritten)
|
|
{
|
|
struct file *file = vma->vm_file;
|
|
struct address_space *mapping = file->f_mapping;
|
|
struct inode *inode = mapping->host;
|
|
struct page *page;
|
|
struct buffer_head bh;
|
|
unsigned long vaddr = (unsigned long)vmf->virtual_address;
|
|
unsigned blkbits = inode->i_blkbits;
|
|
sector_t block;
|
|
pgoff_t size;
|
|
int error;
|
|
int major = 0;
|
|
|
|
size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT;
|
|
if (vmf->pgoff >= size)
|
|
return VM_FAULT_SIGBUS;
|
|
|
|
memset(&bh, 0, sizeof(bh));
|
|
block = (sector_t)vmf->pgoff << (PAGE_SHIFT - blkbits);
|
|
bh.b_bdev = inode->i_sb->s_bdev;
|
|
bh.b_size = PAGE_SIZE;
|
|
|
|
repeat:
|
|
page = find_get_page(mapping, vmf->pgoff);
|
|
if (page) {
|
|
if (!lock_page_or_retry(page, vma->vm_mm, vmf->flags)) {
|
|
page_cache_release(page);
|
|
return VM_FAULT_RETRY;
|
|
}
|
|
if (unlikely(page->mapping != mapping)) {
|
|
unlock_page(page);
|
|
page_cache_release(page);
|
|
goto repeat;
|
|
}
|
|
size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT;
|
|
if (unlikely(vmf->pgoff >= size)) {
|
|
/*
|
|
* We have a struct page covering a hole in the file
|
|
* from a read fault and we've raced with a truncate
|
|
*/
|
|
error = -EIO;
|
|
goto unlock_page;
|
|
}
|
|
}
|
|
|
|
error = get_block(inode, block, &bh, 0);
|
|
if (!error && (bh.b_size < PAGE_SIZE))
|
|
error = -EIO; /* fs corruption? */
|
|
if (error)
|
|
goto unlock_page;
|
|
|
|
if (!buffer_mapped(&bh) && !buffer_unwritten(&bh) && !vmf->cow_page) {
|
|
if (vmf->flags & FAULT_FLAG_WRITE) {
|
|
error = get_block(inode, block, &bh, 1);
|
|
count_vm_event(PGMAJFAULT);
|
|
mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT);
|
|
major = VM_FAULT_MAJOR;
|
|
if (!error && (bh.b_size < PAGE_SIZE))
|
|
error = -EIO;
|
|
if (error)
|
|
goto unlock_page;
|
|
} else {
|
|
return dax_load_hole(mapping, page, vmf);
|
|
}
|
|
}
|
|
|
|
if (vmf->cow_page) {
|
|
struct page *new_page = vmf->cow_page;
|
|
if (buffer_written(&bh))
|
|
error = copy_user_bh(new_page, inode, &bh, vaddr);
|
|
else
|
|
clear_user_highpage(new_page, vaddr);
|
|
if (error)
|
|
goto unlock_page;
|
|
vmf->page = page;
|
|
if (!page) {
|
|
i_mmap_lock_read(mapping);
|
|
/* Check we didn't race with truncate */
|
|
size = (i_size_read(inode) + PAGE_SIZE - 1) >>
|
|
PAGE_SHIFT;
|
|
if (vmf->pgoff >= size) {
|
|
i_mmap_unlock_read(mapping);
|
|
error = -EIO;
|
|
goto out;
|
|
}
|
|
}
|
|
return VM_FAULT_LOCKED;
|
|
}
|
|
|
|
/* Check we didn't race with a read fault installing a new page */
|
|
if (!page && major)
|
|
page = find_lock_page(mapping, vmf->pgoff);
|
|
|
|
if (page) {
|
|
unmap_mapping_range(mapping, vmf->pgoff << PAGE_SHIFT,
|
|
PAGE_CACHE_SIZE, 0);
|
|
delete_from_page_cache(page);
|
|
unlock_page(page);
|
|
page_cache_release(page);
|
|
page = NULL;
|
|
}
|
|
|
|
/*
|
|
* If we successfully insert the new mapping over an unwritten extent,
|
|
* we need to ensure we convert the unwritten extent. If there is an
|
|
* error inserting the mapping, the filesystem needs to leave it as
|
|
* unwritten to prevent exposure of the stale underlying data to
|
|
* userspace, but we still need to call the completion function so
|
|
* the private resources on the mapping buffer can be released. We
|
|
* indicate what the callback should do via the uptodate variable, same
|
|
* as for normal BH based IO completions.
|
|
*/
|
|
error = dax_insert_mapping(inode, &bh, vma, vmf);
|
|
if (buffer_unwritten(&bh)) {
|
|
if (complete_unwritten)
|
|
complete_unwritten(&bh, !error);
|
|
else
|
|
WARN_ON_ONCE(!(vmf->flags & FAULT_FLAG_WRITE));
|
|
}
|
|
|
|
out:
|
|
if (error == -ENOMEM)
|
|
return VM_FAULT_OOM | major;
|
|
/* -EBUSY is fine, somebody else faulted on the same PTE */
|
|
if ((error < 0) && (error != -EBUSY))
|
|
return VM_FAULT_SIGBUS | major;
|
|
return VM_FAULT_NOPAGE | major;
|
|
|
|
unlock_page:
|
|
if (page) {
|
|
unlock_page(page);
|
|
page_cache_release(page);
|
|
}
|
|
goto out;
|
|
}
|
|
EXPORT_SYMBOL(__dax_fault);
|
|
|
|
/**
|
|
* dax_fault - handle a page fault on a DAX file
|
|
* @vma: The virtual memory area where the fault occurred
|
|
* @vmf: The description of the fault
|
|
* @get_block: The filesystem method used to translate file offsets to blocks
|
|
*
|
|
* When a page fault occurs, filesystems may call this helper in their
|
|
* fault handler for DAX files.
|
|
*/
|
|
int dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
|
|
get_block_t get_block, dax_iodone_t complete_unwritten)
|
|
{
|
|
int result;
|
|
struct super_block *sb = file_inode(vma->vm_file)->i_sb;
|
|
|
|
if (vmf->flags & FAULT_FLAG_WRITE) {
|
|
sb_start_pagefault(sb);
|
|
file_update_time(vma->vm_file);
|
|
}
|
|
result = __dax_fault(vma, vmf, get_block, complete_unwritten);
|
|
if (vmf->flags & FAULT_FLAG_WRITE)
|
|
sb_end_pagefault(sb);
|
|
|
|
return result;
|
|
}
|
|
EXPORT_SYMBOL_GPL(dax_fault);
|
|
|
|
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
|
|
/*
|
|
* The 'colour' (ie low bits) within a PMD of a page offset. This comes up
|
|
* more often than one might expect in the below function.
|
|
*/
|
|
#define PG_PMD_COLOUR ((PMD_SIZE >> PAGE_SHIFT) - 1)
|
|
|
|
static void __dax_dbg(struct buffer_head *bh, unsigned long address,
|
|
const char *reason, const char *fn)
|
|
{
|
|
if (bh) {
|
|
char bname[BDEVNAME_SIZE];
|
|
bdevname(bh->b_bdev, bname);
|
|
pr_debug("%s: %s addr: %lx dev %s state %lx start %lld "
|
|
"length %zd fallback: %s\n", fn, current->comm,
|
|
address, bname, bh->b_state, (u64)bh->b_blocknr,
|
|
bh->b_size, reason);
|
|
} else {
|
|
pr_debug("%s: %s addr: %lx fallback: %s\n", fn,
|
|
current->comm, address, reason);
|
|
}
|
|
}
|
|
|
|
#define dax_pmd_dbg(bh, address, reason) __dax_dbg(bh, address, reason, "dax_pmd")
|
|
|
|
int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
|
|
pmd_t *pmd, unsigned int flags, get_block_t get_block,
|
|
dax_iodone_t complete_unwritten)
|
|
{
|
|
struct file *file = vma->vm_file;
|
|
struct address_space *mapping = file->f_mapping;
|
|
struct inode *inode = mapping->host;
|
|
struct buffer_head bh;
|
|
unsigned blkbits = inode->i_blkbits;
|
|
unsigned long pmd_addr = address & PMD_MASK;
|
|
bool write = flags & FAULT_FLAG_WRITE;
|
|
struct block_device *bdev;
|
|
pgoff_t size, pgoff;
|
|
sector_t block;
|
|
int error, result = 0;
|
|
bool alloc = false;
|
|
|
|
/* dax pmd mappings require pfn_t_devmap() */
|
|
if (!IS_ENABLED(CONFIG_FS_DAX_PMD))
|
|
return VM_FAULT_FALLBACK;
|
|
|
|
/* Fall back to PTEs if we're going to COW */
|
|
if (write && !(vma->vm_flags & VM_SHARED)) {
|
|
split_huge_pmd(vma, pmd, address);
|
|
dax_pmd_dbg(NULL, address, "cow write");
|
|
return VM_FAULT_FALLBACK;
|
|
}
|
|
/* If the PMD would extend outside the VMA */
|
|
if (pmd_addr < vma->vm_start) {
|
|
dax_pmd_dbg(NULL, address, "vma start unaligned");
|
|
return VM_FAULT_FALLBACK;
|
|
}
|
|
if ((pmd_addr + PMD_SIZE) > vma->vm_end) {
|
|
dax_pmd_dbg(NULL, address, "vma end unaligned");
|
|
return VM_FAULT_FALLBACK;
|
|
}
|
|
|
|
pgoff = linear_page_index(vma, pmd_addr);
|
|
size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT;
|
|
if (pgoff >= size)
|
|
return VM_FAULT_SIGBUS;
|
|
/* If the PMD would cover blocks out of the file */
|
|
if ((pgoff | PG_PMD_COLOUR) >= size) {
|
|
dax_pmd_dbg(NULL, address,
|
|
"offset + huge page size > file size");
|
|
return VM_FAULT_FALLBACK;
|
|
}
|
|
|
|
memset(&bh, 0, sizeof(bh));
|
|
bh.b_bdev = inode->i_sb->s_bdev;
|
|
block = (sector_t)pgoff << (PAGE_SHIFT - blkbits);
|
|
|
|
bh.b_size = PMD_SIZE;
|
|
|
|
if (get_block(inode, block, &bh, 0) != 0)
|
|
return VM_FAULT_SIGBUS;
|
|
|
|
if (!buffer_mapped(&bh) && write) {
|
|
if (get_block(inode, block, &bh, 1) != 0)
|
|
return VM_FAULT_SIGBUS;
|
|
alloc = true;
|
|
}
|
|
|
|
bdev = bh.b_bdev;
|
|
|
|
/*
|
|
* If the filesystem isn't willing to tell us the length of a hole,
|
|
* just fall back to PTEs. Calling get_block 512 times in a loop
|
|
* would be silly.
|
|
*/
|
|
if (!buffer_size_valid(&bh) || bh.b_size < PMD_SIZE) {
|
|
dax_pmd_dbg(&bh, address, "allocated block too small");
|
|
return VM_FAULT_FALLBACK;
|
|
}
|
|
|
|
/*
|
|
* If we allocated new storage, make sure no process has any
|
|
* zero pages covering this hole
|
|
*/
|
|
if (alloc) {
|
|
loff_t lstart = pgoff << PAGE_SHIFT;
|
|
loff_t lend = lstart + PMD_SIZE - 1; /* inclusive */
|
|
|
|
truncate_pagecache_range(inode, lstart, lend);
|
|
}
|
|
|
|
i_mmap_lock_read(mapping);
|
|
|
|
/*
|
|
* If a truncate happened while we were allocating blocks, we may
|
|
* leave blocks allocated to the file that are beyond EOF. We can't
|
|
* take i_mutex here, so just leave them hanging; they'll be freed
|
|
* when the file is deleted.
|
|
*/
|
|
size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT;
|
|
if (pgoff >= size) {
|
|
result = VM_FAULT_SIGBUS;
|
|
goto out;
|
|
}
|
|
if ((pgoff | PG_PMD_COLOUR) >= size) {
|
|
dax_pmd_dbg(&bh, address,
|
|
"offset + huge page size > file size");
|
|
goto fallback;
|
|
}
|
|
|
|
if (!write && !buffer_mapped(&bh) && buffer_uptodate(&bh)) {
|
|
spinlock_t *ptl;
|
|
pmd_t entry;
|
|
struct page *zero_page = get_huge_zero_page();
|
|
|
|
if (unlikely(!zero_page)) {
|
|
dax_pmd_dbg(&bh, address, "no zero page");
|
|
goto fallback;
|
|
}
|
|
|
|
ptl = pmd_lock(vma->vm_mm, pmd);
|
|
if (!pmd_none(*pmd)) {
|
|
spin_unlock(ptl);
|
|
dax_pmd_dbg(&bh, address, "pmd already present");
|
|
goto fallback;
|
|
}
|
|
|
|
dev_dbg(part_to_dev(bdev->bd_part),
|
|
"%s: %s addr: %lx pfn: <zero> sect: %llx\n",
|
|
__func__, current->comm, address,
|
|
(unsigned long long) to_sector(&bh, inode));
|
|
|
|
entry = mk_pmd(zero_page, vma->vm_page_prot);
|
|
entry = pmd_mkhuge(entry);
|
|
set_pmd_at(vma->vm_mm, pmd_addr, pmd, entry);
|
|
result = VM_FAULT_NOPAGE;
|
|
spin_unlock(ptl);
|
|
} else {
|
|
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) {
|
|
dax_pmd_dbg(&bh, address, "dax-length too small");
|
|
dax_unmap_atomic(bdev, &dax);
|
|
goto fallback;
|
|
}
|
|
if (pfn_t_to_pfn(dax.pfn) & PG_PMD_COLOUR) {
|
|
dax_pmd_dbg(&bh, address, "pfn unaligned");
|
|
dax_unmap_atomic(bdev, &dax);
|
|
goto fallback;
|
|
}
|
|
|
|
if (!pfn_t_devmap(dax.pfn)) {
|
|
dax_unmap_atomic(bdev, &dax);
|
|
dax_pmd_dbg(&bh, address, "pfn not in memmap");
|
|
goto fallback;
|
|
}
|
|
|
|
if (buffer_unwritten(&bh) || buffer_new(&bh)) {
|
|
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);
|
|
|
|
/*
|
|
* For PTE faults we insert a radix tree entry for reads, and
|
|
* leave it clean. Then on the first write we dirty the radix
|
|
* tree entry via the dax_pfn_mkwrite() path. This sequence
|
|
* allows the dax_pfn_mkwrite() call to be simpler and avoid a
|
|
* call into get_block() to translate the pgoff to a sector in
|
|
* order to be able to create a new radix tree entry.
|
|
*
|
|
* The PMD path doesn't have an equivalent to
|
|
* dax_pfn_mkwrite(), though, so for a read followed by a
|
|
* write we traverse all the way through __dax_pmd_fault()
|
|
* twice. This means we can just skip inserting a radix tree
|
|
* entry completely on the initial read and just wait until
|
|
* the write to insert a dirty entry.
|
|
*/
|
|
if (write) {
|
|
error = dax_radix_entry(mapping, pgoff, dax.sector,
|
|
true, true);
|
|
if (error) {
|
|
dax_pmd_dbg(&bh, address,
|
|
"PMD radix insertion failed");
|
|
goto fallback;
|
|
}
|
|
}
|
|
|
|
dev_dbg(part_to_dev(bdev->bd_part),
|
|
"%s: %s addr: %lx pfn: %lx sect: %llx\n",
|
|
__func__, current->comm, address,
|
|
pfn_t_to_pfn(dax.pfn),
|
|
(unsigned long long) dax.sector);
|
|
result |= vmf_insert_pfn_pmd(vma, address, pmd,
|
|
dax.pfn, write);
|
|
}
|
|
|
|
out:
|
|
i_mmap_unlock_read(mapping);
|
|
|
|
if (buffer_unwritten(&bh))
|
|
complete_unwritten(&bh, !(result & VM_FAULT_ERROR));
|
|
|
|
return result;
|
|
|
|
fallback:
|
|
count_vm_event(THP_FAULT_FALLBACK);
|
|
result = VM_FAULT_FALLBACK;
|
|
goto out;
|
|
}
|
|
EXPORT_SYMBOL_GPL(__dax_pmd_fault);
|
|
|
|
/**
|
|
* dax_pmd_fault - handle a PMD fault on a DAX file
|
|
* @vma: The virtual memory area where the fault occurred
|
|
* @vmf: The description of the fault
|
|
* @get_block: The filesystem method used to translate file offsets to blocks
|
|
*
|
|
* When a page fault occurs, filesystems may call this helper in their
|
|
* pmd_fault handler for DAX files.
|
|
*/
|
|
int dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
|
|
pmd_t *pmd, unsigned int flags, get_block_t get_block,
|
|
dax_iodone_t complete_unwritten)
|
|
{
|
|
int result;
|
|
struct super_block *sb = file_inode(vma->vm_file)->i_sb;
|
|
|
|
if (flags & FAULT_FLAG_WRITE) {
|
|
sb_start_pagefault(sb);
|
|
file_update_time(vma->vm_file);
|
|
}
|
|
result = __dax_pmd_fault(vma, address, pmd, flags, get_block,
|
|
complete_unwritten);
|
|
if (flags & FAULT_FLAG_WRITE)
|
|
sb_end_pagefault(sb);
|
|
|
|
return result;
|
|
}
|
|
EXPORT_SYMBOL_GPL(dax_pmd_fault);
|
|
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
|
|
|
|
/**
|
|
* dax_pfn_mkwrite - handle first write to DAX page
|
|
* @vma: The virtual memory area where the fault occurred
|
|
* @vmf: The description of the fault
|
|
*/
|
|
int dax_pfn_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
|
|
{
|
|
struct file *file = vma->vm_file;
|
|
|
|
/*
|
|
* We pass NO_SECTOR to dax_radix_entry() because we expect that a
|
|
* RADIX_DAX_PTE entry already exists in the radix tree from a
|
|
* previous call to __dax_fault(). We just want to look up that PTE
|
|
* entry using vmf->pgoff and make sure the dirty tag is set. This
|
|
* saves us from having to make a call to get_block() here to look
|
|
* up the sector.
|
|
*/
|
|
dax_radix_entry(file->f_mapping, vmf->pgoff, NO_SECTOR, false, true);
|
|
return VM_FAULT_NOPAGE;
|
|
}
|
|
EXPORT_SYMBOL_GPL(dax_pfn_mkwrite);
|
|
|
|
/**
|
|
* dax_zero_page_range - zero a range within a page of a DAX file
|
|
* @inode: The file being truncated
|
|
* @from: The file offset that is being truncated to
|
|
* @length: The number of bytes to zero
|
|
* @get_block: The filesystem method used to translate file offsets to blocks
|
|
*
|
|
* This function can be called by a filesystem when it is zeroing part of a
|
|
* page in a DAX file. This is intended for hole-punch operations. If
|
|
* you are truncating a file, the helper function dax_truncate_page() may be
|
|
* more convenient.
|
|
*
|
|
* We work in terms of PAGE_CACHE_SIZE here for commonality with
|
|
* block_truncate_page(), but we could go down to PAGE_SIZE if the filesystem
|
|
* took care of disposing of the unnecessary blocks. Even if the filesystem
|
|
* block size is smaller than PAGE_SIZE, we have to zero the rest of the page
|
|
* since the file might be mmapped.
|
|
*/
|
|
int dax_zero_page_range(struct inode *inode, loff_t from, unsigned length,
|
|
get_block_t get_block)
|
|
{
|
|
struct buffer_head bh;
|
|
pgoff_t index = from >> PAGE_CACHE_SHIFT;
|
|
unsigned offset = from & (PAGE_CACHE_SIZE-1);
|
|
int err;
|
|
|
|
/* Block boundary? Nothing to do */
|
|
if (!length)
|
|
return 0;
|
|
BUG_ON((offset + length) > PAGE_CACHE_SIZE);
|
|
|
|
memset(&bh, 0, sizeof(bh));
|
|
bh.b_bdev = inode->i_sb->s_bdev;
|
|
bh.b_size = PAGE_CACHE_SIZE;
|
|
err = get_block(inode, index, &bh, 0);
|
|
if (err < 0)
|
|
return err;
|
|
if (buffer_written(&bh)) {
|
|
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;
|
|
}
|
|
EXPORT_SYMBOL_GPL(dax_zero_page_range);
|
|
|
|
/**
|
|
* dax_truncate_page - handle a partial page being truncated in a DAX file
|
|
* @inode: The file being truncated
|
|
* @from: The file offset that is being truncated to
|
|
* @get_block: The filesystem method used to translate file offsets to blocks
|
|
*
|
|
* Similar to block_truncate_page(), this function can be called by a
|
|
* filesystem when it is truncating a DAX file to handle the partial page.
|
|
*
|
|
* We work in terms of PAGE_CACHE_SIZE here for commonality with
|
|
* block_truncate_page(), but we could go down to PAGE_SIZE if the filesystem
|
|
* took care of disposing of the unnecessary blocks. Even if the filesystem
|
|
* block size is smaller than PAGE_SIZE, we have to zero the rest of the page
|
|
* since the file might be mmapped.
|
|
*/
|
|
int dax_truncate_page(struct inode *inode, loff_t from, get_block_t get_block)
|
|
{
|
|
unsigned length = PAGE_CACHE_ALIGN(from) - from;
|
|
return dax_zero_page_range(inode, from, length, get_block);
|
|
}
|
|
EXPORT_SYMBOL_GPL(dax_truncate_page);
|