![Eric Sandeen](/assets/img/avatar_default.png)
This isn't functionally apparent for some reason, but when we test io at extreme offsets at the end of the loff_t rang, such as in fstests xfs/071, the calculation of "max" in dax_io() can be wrong due to pos + size overflowing. For example, # xfs_io -c "pwrite 9223372036854771712 512" /mnt/test/file enters dax_io with: start 0x7ffffffffffff000 end 0x7ffffffffffff200 and the rounded up "size" variable is 0x1000. This yields: pos + size 0x8000000000000000 (overflows loff_t) end 0x7ffffffffffff200 Due to the overflow, the min() function picks the wrong value for the "max" variable, and when we send (max - pos) into i.e. copy_from_iter_pmem() it is also the wrong value. This somehow(tm) gets magically absorbed without incident, probably because iter->count is correct. But it seems best to fix it up properly by comparing the two values as unsigned. Signed-off-by: Eric Sandeen <sandeen@redhat.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
1294 lines
36 KiB
C
1294 lines
36 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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/*
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* We use lowest available bit in exceptional entry for locking, other two
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* bits to determine entry type. In total 3 special bits.
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*/
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#define RADIX_DAX_SHIFT (RADIX_TREE_EXCEPTIONAL_SHIFT + 3)
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#define RADIX_DAX_PTE (1 << (RADIX_TREE_EXCEPTIONAL_SHIFT + 1))
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#define RADIX_DAX_PMD (1 << (RADIX_TREE_EXCEPTIONAL_SHIFT + 2))
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#define RADIX_DAX_TYPE_MASK (RADIX_DAX_PTE | RADIX_DAX_PMD)
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#define RADIX_DAX_TYPE(entry) ((unsigned long)entry & RADIX_DAX_TYPE_MASK)
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#define RADIX_DAX_SECTOR(entry) (((unsigned long)entry >> RADIX_DAX_SHIFT))
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#define RADIX_DAX_ENTRY(sector, pmd) ((void *)((unsigned long)sector << \
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RADIX_DAX_SHIFT | (pmd ? RADIX_DAX_PMD : RADIX_DAX_PTE) | \
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RADIX_TREE_EXCEPTIONAL_ENTRY))
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/* We choose 4096 entries - same as per-zone page wait tables */
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#define DAX_WAIT_TABLE_BITS 12
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#define DAX_WAIT_TABLE_ENTRIES (1 << DAX_WAIT_TABLE_BITS)
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wait_queue_head_t wait_table[DAX_WAIT_TABLE_ENTRIES];
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static int __init init_dax_wait_table(void)
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{
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int i;
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for (i = 0; i < DAX_WAIT_TABLE_ENTRIES; i++)
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init_waitqueue_head(wait_table + i);
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return 0;
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}
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fs_initcall(init_dax_wait_table);
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static wait_queue_head_t *dax_entry_waitqueue(struct address_space *mapping,
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pgoff_t index)
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{
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unsigned long hash = hash_long((unsigned long)mapping ^ index,
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DAX_WAIT_TABLE_BITS);
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return wait_table + hash;
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}
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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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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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unsigned blkbits = inode->i_blkbits;
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sector_t file_blks = (i_size_read(inode) + (1 << blkbits) - 1)
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>> blkbits;
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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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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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/*
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* We allow uninitialized buffers for writes
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* beyond EOF as those cannot race with faults
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*/
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WARN_ON_ONCE(
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(buffer_new(bh) && block < file_blks) ||
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(rw == WRITE && buffer_unwritten(bh)));
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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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dax.addr += first;
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size = map_len - first;
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}
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/*
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* pos + size is one past the last offset for IO,
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* so pos + size can overflow loff_t at extreme offsets.
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* Cast to u64 to catch this and get the true minimum.
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*/
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max = min_t(u64, 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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* @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, 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 pos = iocb->ki_pos;
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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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inode_lock(inode);
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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 (end_io) {
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int err;
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err = end_io(iocb, pos, retval, bh.b_private);
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if (err)
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retval = err;
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}
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if (!(flags & DIO_SKIP_DIO_COUNT))
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inode_dio_end(inode);
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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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* DAX radix tree locking
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*/
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struct exceptional_entry_key {
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struct address_space *mapping;
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unsigned long index;
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};
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struct wait_exceptional_entry_queue {
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wait_queue_t wait;
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struct exceptional_entry_key key;
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};
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static int wake_exceptional_entry_func(wait_queue_t *wait, unsigned int mode,
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int sync, void *keyp)
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{
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struct exceptional_entry_key *key = keyp;
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struct wait_exceptional_entry_queue *ewait =
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container_of(wait, struct wait_exceptional_entry_queue, wait);
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if (key->mapping != ewait->key.mapping ||
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key->index != ewait->key.index)
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return 0;
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return autoremove_wake_function(wait, mode, sync, NULL);
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}
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/*
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* Check whether the given slot is locked. The function must be called with
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* mapping->tree_lock held
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*/
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static inline int slot_locked(struct address_space *mapping, void **slot)
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{
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unsigned long entry = (unsigned long)
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radix_tree_deref_slot_protected(slot, &mapping->tree_lock);
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return entry & RADIX_DAX_ENTRY_LOCK;
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}
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/*
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* Mark the given slot is locked. The function must be called with
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* mapping->tree_lock held
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*/
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static inline void *lock_slot(struct address_space *mapping, void **slot)
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{
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unsigned long entry = (unsigned long)
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radix_tree_deref_slot_protected(slot, &mapping->tree_lock);
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entry |= RADIX_DAX_ENTRY_LOCK;
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radix_tree_replace_slot(slot, (void *)entry);
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return (void *)entry;
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}
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/*
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* Mark the given slot is unlocked. The function must be called with
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* mapping->tree_lock held
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*/
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static inline void *unlock_slot(struct address_space *mapping, void **slot)
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{
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unsigned long entry = (unsigned long)
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radix_tree_deref_slot_protected(slot, &mapping->tree_lock);
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entry &= ~(unsigned long)RADIX_DAX_ENTRY_LOCK;
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radix_tree_replace_slot(slot, (void *)entry);
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return (void *)entry;
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}
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/*
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* Lookup entry in radix tree, wait for it to become unlocked if it is
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* exceptional entry and return it. The caller must call
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* put_unlocked_mapping_entry() when he decided not to lock the entry or
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* put_locked_mapping_entry() when he locked the entry and now wants to
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* unlock it.
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*
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* The function must be called with mapping->tree_lock held.
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*/
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static void *get_unlocked_mapping_entry(struct address_space *mapping,
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pgoff_t index, void ***slotp)
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{
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void *ret, **slot;
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struct wait_exceptional_entry_queue ewait;
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wait_queue_head_t *wq = dax_entry_waitqueue(mapping, index);
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init_wait(&ewait.wait);
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ewait.wait.func = wake_exceptional_entry_func;
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ewait.key.mapping = mapping;
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ewait.key.index = index;
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for (;;) {
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ret = __radix_tree_lookup(&mapping->page_tree, index, NULL,
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&slot);
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if (!ret || !radix_tree_exceptional_entry(ret) ||
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!slot_locked(mapping, slot)) {
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if (slotp)
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*slotp = slot;
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return ret;
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}
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prepare_to_wait_exclusive(wq, &ewait.wait,
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TASK_UNINTERRUPTIBLE);
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spin_unlock_irq(&mapping->tree_lock);
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schedule();
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finish_wait(wq, &ewait.wait);
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spin_lock_irq(&mapping->tree_lock);
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}
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}
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/*
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* Find radix tree entry at given index. If it points to a page, return with
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* the page locked. If it points to the exceptional entry, return with the
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* radix tree entry locked. If the radix tree doesn't contain given index,
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* create empty exceptional entry for the index and return with it locked.
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*
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* Note: Unlike filemap_fault() we don't honor FAULT_FLAG_RETRY flags. For
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* persistent memory the benefit is doubtful. We can add that later if we can
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* show it helps.
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*/
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static void *grab_mapping_entry(struct address_space *mapping, pgoff_t index)
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{
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void *ret, **slot;
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restart:
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spin_lock_irq(&mapping->tree_lock);
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ret = get_unlocked_mapping_entry(mapping, index, &slot);
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/* No entry for given index? Make sure radix tree is big enough. */
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if (!ret) {
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int err;
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spin_unlock_irq(&mapping->tree_lock);
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err = radix_tree_preload(
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mapping_gfp_mask(mapping) & ~__GFP_HIGHMEM);
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if (err)
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return ERR_PTR(err);
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ret = (void *)(RADIX_TREE_EXCEPTIONAL_ENTRY |
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RADIX_DAX_ENTRY_LOCK);
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spin_lock_irq(&mapping->tree_lock);
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err = radix_tree_insert(&mapping->page_tree, index, ret);
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radix_tree_preload_end();
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if (err) {
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spin_unlock_irq(&mapping->tree_lock);
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/* Someone already created the entry? */
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if (err == -EEXIST)
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goto restart;
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return ERR_PTR(err);
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}
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/* Good, we have inserted empty locked entry into the tree. */
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mapping->nrexceptional++;
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spin_unlock_irq(&mapping->tree_lock);
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return ret;
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}
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/* Normal page in radix tree? */
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if (!radix_tree_exceptional_entry(ret)) {
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struct page *page = ret;
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get_page(page);
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spin_unlock_irq(&mapping->tree_lock);
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lock_page(page);
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/* Page got truncated? Retry... */
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if (unlikely(page->mapping != mapping)) {
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unlock_page(page);
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put_page(page);
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goto restart;
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}
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return page;
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}
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ret = lock_slot(mapping, slot);
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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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void dax_wake_mapping_entry_waiter(struct address_space *mapping,
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pgoff_t index, bool wake_all)
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{
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wait_queue_head_t *wq = dax_entry_waitqueue(mapping, index);
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/*
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* Checking for locked entry and prepare_to_wait_exclusive() happens
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* under mapping->tree_lock, ditto for entry handling in our callers.
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* So at this point all tasks that could have seen our entry locked
|
|
* must be in the waitqueue and the following check will see them.
|
|
*/
|
|
if (waitqueue_active(wq)) {
|
|
struct exceptional_entry_key key;
|
|
|
|
key.mapping = mapping;
|
|
key.index = index;
|
|
__wake_up(wq, TASK_NORMAL, wake_all ? 0 : 1, &key);
|
|
}
|
|
}
|
|
|
|
void dax_unlock_mapping_entry(struct address_space *mapping, pgoff_t index)
|
|
{
|
|
void *ret, **slot;
|
|
|
|
spin_lock_irq(&mapping->tree_lock);
|
|
ret = __radix_tree_lookup(&mapping->page_tree, index, NULL, &slot);
|
|
if (WARN_ON_ONCE(!ret || !radix_tree_exceptional_entry(ret) ||
|
|
!slot_locked(mapping, slot))) {
|
|
spin_unlock_irq(&mapping->tree_lock);
|
|
return;
|
|
}
|
|
unlock_slot(mapping, slot);
|
|
spin_unlock_irq(&mapping->tree_lock);
|
|
dax_wake_mapping_entry_waiter(mapping, index, false);
|
|
}
|
|
|
|
static void put_locked_mapping_entry(struct address_space *mapping,
|
|
pgoff_t index, void *entry)
|
|
{
|
|
if (!radix_tree_exceptional_entry(entry)) {
|
|
unlock_page(entry);
|
|
put_page(entry);
|
|
} else {
|
|
dax_unlock_mapping_entry(mapping, index);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Called when we are done with radix tree entry we looked up via
|
|
* get_unlocked_mapping_entry() and which we didn't lock in the end.
|
|
*/
|
|
static void put_unlocked_mapping_entry(struct address_space *mapping,
|
|
pgoff_t index, void *entry)
|
|
{
|
|
if (!radix_tree_exceptional_entry(entry))
|
|
return;
|
|
|
|
/* We have to wake up next waiter for the radix tree entry lock */
|
|
dax_wake_mapping_entry_waiter(mapping, index, false);
|
|
}
|
|
|
|
/*
|
|
* Delete exceptional DAX entry at @index from @mapping. Wait for radix tree
|
|
* entry to get unlocked before deleting it.
|
|
*/
|
|
int dax_delete_mapping_entry(struct address_space *mapping, pgoff_t index)
|
|
{
|
|
void *entry;
|
|
|
|
spin_lock_irq(&mapping->tree_lock);
|
|
entry = get_unlocked_mapping_entry(mapping, index, NULL);
|
|
/*
|
|
* This gets called from truncate / punch_hole path. As such, the caller
|
|
* must hold locks protecting against concurrent modifications of the
|
|
* radix tree (usually fs-private i_mmap_sem for writing). Since the
|
|
* caller has seen exceptional entry for this index, we better find it
|
|
* at that index as well...
|
|
*/
|
|
if (WARN_ON_ONCE(!entry || !radix_tree_exceptional_entry(entry))) {
|
|
spin_unlock_irq(&mapping->tree_lock);
|
|
return 0;
|
|
}
|
|
radix_tree_delete(&mapping->page_tree, index);
|
|
mapping->nrexceptional--;
|
|
spin_unlock_irq(&mapping->tree_lock);
|
|
dax_wake_mapping_entry_waiter(mapping, index, true);
|
|
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* The user has performed a load from a hole in the file. Allocating
|
|
* a new page in the file would cause excessive storage usage for
|
|
* workloads with sparse files. We allocate a page cache page instead.
|
|
* We'll kick it out of the page cache if it's ever written to,
|
|
* otherwise it will simply fall out of the page cache under memory
|
|
* pressure without ever having been dirtied.
|
|
*/
|
|
static int dax_load_hole(struct address_space *mapping, void *entry,
|
|
struct vm_fault *vmf)
|
|
{
|
|
struct page *page;
|
|
|
|
/* Hole page already exists? Return it... */
|
|
if (!radix_tree_exceptional_entry(entry)) {
|
|
vmf->page = entry;
|
|
return VM_FAULT_LOCKED;
|
|
}
|
|
|
|
/* This will replace locked radix tree entry with a hole page */
|
|
page = find_or_create_page(mapping, vmf->pgoff,
|
|
vmf->gfp_mask | __GFP_ZERO);
|
|
if (!page) {
|
|
put_locked_mapping_entry(mapping, vmf->pgoff, entry);
|
|
return VM_FAULT_OOM;
|
|
}
|
|
vmf->page = page;
|
|
return VM_FAULT_LOCKED;
|
|
}
|
|
|
|
static int copy_user_bh(struct page *to, struct inode *inode,
|
|
struct buffer_head *bh, unsigned long vaddr)
|
|
{
|
|
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_map_atomic(bdev, &dax) < 0)
|
|
return PTR_ERR(dax.addr);
|
|
vto = kmap_atomic(to);
|
|
copy_user_page(vto, (void __force *)dax.addr, vaddr, to);
|
|
kunmap_atomic(vto);
|
|
dax_unmap_atomic(bdev, &dax);
|
|
return 0;
|
|
}
|
|
|
|
#define DAX_PMD_INDEX(page_index) (page_index & (PMD_MASK >> PAGE_SHIFT))
|
|
|
|
static void *dax_insert_mapping_entry(struct address_space *mapping,
|
|
struct vm_fault *vmf,
|
|
void *entry, sector_t sector)
|
|
{
|
|
struct radix_tree_root *page_tree = &mapping->page_tree;
|
|
int error = 0;
|
|
bool hole_fill = false;
|
|
void *new_entry;
|
|
pgoff_t index = vmf->pgoff;
|
|
|
|
if (vmf->flags & FAULT_FLAG_WRITE)
|
|
__mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
|
|
|
|
/* Replacing hole page with block mapping? */
|
|
if (!radix_tree_exceptional_entry(entry)) {
|
|
hole_fill = true;
|
|
/*
|
|
* Unmap the page now before we remove it from page cache below.
|
|
* The page is locked so it cannot be faulted in again.
|
|
*/
|
|
unmap_mapping_range(mapping, vmf->pgoff << PAGE_SHIFT,
|
|
PAGE_SIZE, 0);
|
|
error = radix_tree_preload(vmf->gfp_mask & ~__GFP_HIGHMEM);
|
|
if (error)
|
|
return ERR_PTR(error);
|
|
}
|
|
|
|
spin_lock_irq(&mapping->tree_lock);
|
|
new_entry = (void *)((unsigned long)RADIX_DAX_ENTRY(sector, false) |
|
|
RADIX_DAX_ENTRY_LOCK);
|
|
if (hole_fill) {
|
|
__delete_from_page_cache(entry, NULL);
|
|
/* Drop pagecache reference */
|
|
put_page(entry);
|
|
error = radix_tree_insert(page_tree, index, new_entry);
|
|
if (error) {
|
|
new_entry = ERR_PTR(error);
|
|
goto unlock;
|
|
}
|
|
mapping->nrexceptional++;
|
|
} else {
|
|
void **slot;
|
|
void *ret;
|
|
|
|
ret = __radix_tree_lookup(page_tree, index, NULL, &slot);
|
|
WARN_ON_ONCE(ret != entry);
|
|
radix_tree_replace_slot(slot, new_entry);
|
|
}
|
|
if (vmf->flags & FAULT_FLAG_WRITE)
|
|
radix_tree_tag_set(page_tree, index, PAGECACHE_TAG_DIRTY);
|
|
unlock:
|
|
spin_unlock_irq(&mapping->tree_lock);
|
|
if (hole_fill) {
|
|
radix_tree_preload_end();
|
|
/*
|
|
* We don't need hole page anymore, it has been replaced with
|
|
* locked radix tree entry now.
|
|
*/
|
|
if (mapping->a_ops->freepage)
|
|
mapping->a_ops->freepage(entry);
|
|
unlock_page(entry);
|
|
put_page(entry);
|
|
}
|
|
return new_entry;
|
|
}
|
|
|
|
static int dax_writeback_one(struct block_device *bdev,
|
|
struct address_space *mapping, pgoff_t index, void *entry)
|
|
{
|
|
struct radix_tree_root *page_tree = &mapping->page_tree;
|
|
int type = RADIX_DAX_TYPE(entry);
|
|
struct radix_tree_node *node;
|
|
struct blk_dax_ctl dax;
|
|
void **slot;
|
|
int ret = 0;
|
|
|
|
spin_lock_irq(&mapping->tree_lock);
|
|
/*
|
|
* Regular page slots are stabilized by the page lock even
|
|
* without the tree itself locked. These unlocked entries
|
|
* need verification under the tree lock.
|
|
*/
|
|
if (!__radix_tree_lookup(page_tree, index, &node, &slot))
|
|
goto unlock;
|
|
if (*slot != entry)
|
|
goto unlock;
|
|
|
|
/* another fsync thread may have already written back this entry */
|
|
if (!radix_tree_tag_get(page_tree, index, PAGECACHE_TAG_TOWRITE))
|
|
goto unlock;
|
|
|
|
if (WARN_ON_ONCE(type != RADIX_DAX_PTE && type != RADIX_DAX_PMD)) {
|
|
ret = -EIO;
|
|
goto unlock;
|
|
}
|
|
|
|
dax.sector = RADIX_DAX_SECTOR(entry);
|
|
dax.size = (type == RADIX_DAX_PMD ? PMD_SIZE : PAGE_SIZE);
|
|
spin_unlock_irq(&mapping->tree_lock);
|
|
|
|
/*
|
|
* We cannot hold tree_lock while calling dax_map_atomic() because it
|
|
* eventually calls cond_resched().
|
|
*/
|
|
ret = dax_map_atomic(bdev, &dax);
|
|
if (ret < 0)
|
|
return ret;
|
|
|
|
if (WARN_ON_ONCE(ret < dax.size)) {
|
|
ret = -EIO;
|
|
goto unmap;
|
|
}
|
|
|
|
wb_cache_pmem(dax.addr, dax.size);
|
|
|
|
spin_lock_irq(&mapping->tree_lock);
|
|
radix_tree_tag_clear(page_tree, index, PAGECACHE_TAG_TOWRITE);
|
|
spin_unlock_irq(&mapping->tree_lock);
|
|
unmap:
|
|
dax_unmap_atomic(bdev, &dax);
|
|
return ret;
|
|
|
|
unlock:
|
|
spin_unlock_irq(&mapping->tree_lock);
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Flush the mapping to the persistent domain within the byte range of [start,
|
|
* end]. This is required by data integrity operations to ensure file data is
|
|
* on persistent storage prior to completion of the operation.
|
|
*/
|
|
int dax_writeback_mapping_range(struct address_space *mapping,
|
|
struct block_device *bdev, struct writeback_control *wbc)
|
|
{
|
|
struct inode *inode = mapping->host;
|
|
pgoff_t start_index, end_index, pmd_index;
|
|
pgoff_t indices[PAGEVEC_SIZE];
|
|
struct pagevec pvec;
|
|
bool done = false;
|
|
int i, ret = 0;
|
|
void *entry;
|
|
|
|
if (WARN_ON_ONCE(inode->i_blkbits != PAGE_SHIFT))
|
|
return -EIO;
|
|
|
|
if (!mapping->nrexceptional || wbc->sync_mode != WB_SYNC_ALL)
|
|
return 0;
|
|
|
|
start_index = wbc->range_start >> PAGE_SHIFT;
|
|
end_index = wbc->range_end >> PAGE_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 address_space *mapping,
|
|
struct buffer_head *bh, void **entryp,
|
|
struct vm_area_struct *vma, struct vm_fault *vmf)
|
|
{
|
|
unsigned long vaddr = (unsigned long)vmf->virtual_address;
|
|
struct block_device *bdev = bh->b_bdev;
|
|
struct blk_dax_ctl dax = {
|
|
.sector = to_sector(bh, mapping->host),
|
|
.size = bh->b_size,
|
|
};
|
|
void *ret;
|
|
void *entry = *entryp;
|
|
|
|
if (dax_map_atomic(bdev, &dax) < 0)
|
|
return PTR_ERR(dax.addr);
|
|
dax_unmap_atomic(bdev, &dax);
|
|
|
|
ret = dax_insert_mapping_entry(mapping, vmf, entry, dax.sector);
|
|
if (IS_ERR(ret))
|
|
return PTR_ERR(ret);
|
|
*entryp = ret;
|
|
|
|
return vm_insert_mixed(vma, vaddr, dax.pfn);
|
|
}
|
|
|
|
/**
|
|
* __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. __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)
|
|
{
|
|
struct file *file = vma->vm_file;
|
|
struct address_space *mapping = file->f_mapping;
|
|
struct inode *inode = mapping->host;
|
|
void *entry;
|
|
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;
|
|
|
|
/*
|
|
* Check whether offset isn't beyond end of file now. Caller is supposed
|
|
* to hold locks serializing us with truncate / punch hole so this is
|
|
* a reliable test.
|
|
*/
|
|
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;
|
|
|
|
entry = grab_mapping_entry(mapping, vmf->pgoff);
|
|
if (IS_ERR(entry)) {
|
|
error = PTR_ERR(entry);
|
|
goto out;
|
|
}
|
|
|
|
error = get_block(inode, block, &bh, 0);
|
|
if (!error && (bh.b_size < PAGE_SIZE))
|
|
error = -EIO; /* fs corruption? */
|
|
if (error)
|
|
goto unlock_entry;
|
|
|
|
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_entry;
|
|
if (!radix_tree_exceptional_entry(entry)) {
|
|
vmf->page = entry;
|
|
return VM_FAULT_LOCKED;
|
|
}
|
|
vmf->entry = entry;
|
|
return VM_FAULT_DAX_LOCKED;
|
|
}
|
|
|
|
if (!buffer_mapped(&bh)) {
|
|
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_entry;
|
|
} else {
|
|
return dax_load_hole(mapping, entry, vmf);
|
|
}
|
|
}
|
|
|
|
/* Filesystem should not return unwritten buffers to us! */
|
|
WARN_ON_ONCE(buffer_unwritten(&bh) || buffer_new(&bh));
|
|
error = dax_insert_mapping(mapping, &bh, &entry, vma, vmf);
|
|
unlock_entry:
|
|
put_locked_mapping_entry(mapping, vmf->pgoff, entry);
|
|
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;
|
|
}
|
|
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)
|
|
{
|
|
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);
|
|
if (vmf->flags & FAULT_FLAG_WRITE)
|
|
sb_end_pagefault(sb);
|
|
|
|
return result;
|
|
}
|
|
EXPORT_SYMBOL_GPL(dax_fault);
|
|
|
|
#if defined(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")
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int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
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pmd_t *pmd, unsigned int flags, get_block_t get_block)
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{
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struct file *file = vma->vm_file;
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struct address_space *mapping = file->f_mapping;
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struct inode *inode = mapping->host;
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struct buffer_head bh;
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unsigned blkbits = inode->i_blkbits;
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unsigned long pmd_addr = address & PMD_MASK;
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bool write = flags & FAULT_FLAG_WRITE;
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struct block_device *bdev;
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pgoff_t size, pgoff;
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sector_t block;
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int result = 0;
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bool alloc = false;
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/* dax pmd mappings require pfn_t_devmap() */
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if (!IS_ENABLED(CONFIG_FS_DAX_PMD))
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return VM_FAULT_FALLBACK;
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/* Fall back to PTEs if we're going to COW */
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if (write && !(vma->vm_flags & VM_SHARED)) {
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split_huge_pmd(vma, pmd, address);
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dax_pmd_dbg(NULL, address, "cow write");
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return VM_FAULT_FALLBACK;
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}
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/* If the PMD would extend outside the VMA */
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if (pmd_addr < vma->vm_start) {
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dax_pmd_dbg(NULL, address, "vma start unaligned");
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return VM_FAULT_FALLBACK;
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}
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if ((pmd_addr + PMD_SIZE) > vma->vm_end) {
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dax_pmd_dbg(NULL, address, "vma end unaligned");
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return VM_FAULT_FALLBACK;
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}
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pgoff = linear_page_index(vma, pmd_addr);
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size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT;
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if (pgoff >= size)
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return VM_FAULT_SIGBUS;
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/* If the PMD would cover blocks out of the file */
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if ((pgoff | PG_PMD_COLOUR) >= size) {
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dax_pmd_dbg(NULL, address,
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"offset + huge page size > file size");
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return VM_FAULT_FALLBACK;
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}
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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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block = (sector_t)pgoff << (PAGE_SHIFT - blkbits);
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bh.b_size = PMD_SIZE;
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if (get_block(inode, block, &bh, 0) != 0)
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return VM_FAULT_SIGBUS;
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if (!buffer_mapped(&bh) && write) {
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if (get_block(inode, block, &bh, 1) != 0)
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return VM_FAULT_SIGBUS;
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alloc = true;
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WARN_ON_ONCE(buffer_unwritten(&bh) || buffer_new(&bh));
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}
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bdev = bh.b_bdev;
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/*
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* If the filesystem isn't willing to tell us the length of a hole,
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* just fall back to PTEs. Calling get_block 512 times in a loop
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* would be silly.
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*/
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if (!buffer_size_valid(&bh) || bh.b_size < PMD_SIZE) {
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dax_pmd_dbg(&bh, address, "allocated block too small");
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return VM_FAULT_FALLBACK;
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}
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/*
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* If we allocated new storage, make sure no process has any
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* zero pages covering this hole
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*/
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if (alloc) {
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loff_t lstart = pgoff << PAGE_SHIFT;
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loff_t lend = lstart + PMD_SIZE - 1; /* inclusive */
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truncate_pagecache_range(inode, lstart, lend);
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}
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if (!write && !buffer_mapped(&bh)) {
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spinlock_t *ptl;
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pmd_t entry;
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struct page *zero_page = get_huge_zero_page();
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if (unlikely(!zero_page)) {
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dax_pmd_dbg(&bh, address, "no zero page");
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goto fallback;
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}
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ptl = pmd_lock(vma->vm_mm, pmd);
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if (!pmd_none(*pmd)) {
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spin_unlock(ptl);
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dax_pmd_dbg(&bh, address, "pmd already present");
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goto fallback;
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}
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dev_dbg(part_to_dev(bdev->bd_part),
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"%s: %s addr: %lx pfn: <zero> sect: %llx\n",
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__func__, current->comm, address,
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(unsigned long long) to_sector(&bh, inode));
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entry = mk_pmd(zero_page, vma->vm_page_prot);
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entry = pmd_mkhuge(entry);
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set_pmd_at(vma->vm_mm, pmd_addr, pmd, entry);
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result = VM_FAULT_NOPAGE;
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spin_unlock(ptl);
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} else {
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struct blk_dax_ctl dax = {
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.sector = to_sector(&bh, inode),
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.size = PMD_SIZE,
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};
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long length = dax_map_atomic(bdev, &dax);
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if (length < 0) {
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dax_pmd_dbg(&bh, address, "dax-error fallback");
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goto fallback;
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}
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if (length < PMD_SIZE) {
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dax_pmd_dbg(&bh, address, "dax-length too small");
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dax_unmap_atomic(bdev, &dax);
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goto fallback;
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}
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if (pfn_t_to_pfn(dax.pfn) & PG_PMD_COLOUR) {
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dax_pmd_dbg(&bh, address, "pfn unaligned");
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dax_unmap_atomic(bdev, &dax);
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goto fallback;
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}
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if (!pfn_t_devmap(dax.pfn)) {
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dax_unmap_atomic(bdev, &dax);
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dax_pmd_dbg(&bh, address, "pfn not in memmap");
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goto fallback;
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}
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dax_unmap_atomic(bdev, &dax);
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/*
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* For PTE faults we insert a radix tree entry for reads, and
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* leave it clean. Then on the first write we dirty the radix
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* tree entry via the dax_pfn_mkwrite() path. This sequence
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* allows the dax_pfn_mkwrite() call to be simpler and avoid a
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* call into get_block() to translate the pgoff to a sector in
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* order to be able to create a new radix tree entry.
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*
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* The PMD path doesn't have an equivalent to
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* dax_pfn_mkwrite(), though, so for a read followed by a
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* write we traverse all the way through __dax_pmd_fault()
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* twice. This means we can just skip inserting a radix tree
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* entry completely on the initial read and just wait until
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* the write to insert a dirty entry.
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*/
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if (write) {
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/*
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* We should insert radix-tree entry and dirty it here.
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* For now this is broken...
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*/
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}
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dev_dbg(part_to_dev(bdev->bd_part),
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"%s: %s addr: %lx pfn: %lx sect: %llx\n",
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__func__, current->comm, address,
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pfn_t_to_pfn(dax.pfn),
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(unsigned long long) dax.sector);
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result |= vmf_insert_pfn_pmd(vma, address, pmd,
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dax.pfn, write);
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}
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out:
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return result;
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fallback:
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count_vm_event(THP_FAULT_FALLBACK);
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result = VM_FAULT_FALLBACK;
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goto out;
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}
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EXPORT_SYMBOL_GPL(__dax_pmd_fault);
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/**
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* dax_pmd_fault - handle a PMD fault on a DAX file
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* @vma: The virtual memory area where the fault occurred
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* @vmf: The description of the fault
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* @get_block: The filesystem method used to translate file offsets to blocks
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*
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* When a page fault occurs, filesystems may call this helper in their
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* pmd_fault handler for DAX files.
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*/
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int dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
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pmd_t *pmd, unsigned int flags, get_block_t get_block)
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{
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int result;
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struct super_block *sb = file_inode(vma->vm_file)->i_sb;
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|
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if (flags & FAULT_FLAG_WRITE) {
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sb_start_pagefault(sb);
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file_update_time(vma->vm_file);
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}
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result = __dax_pmd_fault(vma, address, pmd, flags, get_block);
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if (flags & FAULT_FLAG_WRITE)
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sb_end_pagefault(sb);
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return result;
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}
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EXPORT_SYMBOL_GPL(dax_pmd_fault);
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#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
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/**
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* dax_pfn_mkwrite - handle first write to DAX page
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* @vma: The virtual memory area where the fault occurred
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* @vmf: The description of the fault
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*/
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int dax_pfn_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
|
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{
|
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struct file *file = vma->vm_file;
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struct address_space *mapping = file->f_mapping;
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void *entry;
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pgoff_t index = vmf->pgoff;
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|
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spin_lock_irq(&mapping->tree_lock);
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entry = get_unlocked_mapping_entry(mapping, index, NULL);
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if (!entry || !radix_tree_exceptional_entry(entry))
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goto out;
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radix_tree_tag_set(&mapping->page_tree, index, PAGECACHE_TAG_DIRTY);
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put_unlocked_mapping_entry(mapping, index, entry);
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out:
|
|
spin_unlock_irq(&mapping->tree_lock);
|
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return VM_FAULT_NOPAGE;
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}
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EXPORT_SYMBOL_GPL(dax_pfn_mkwrite);
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|
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static bool dax_range_is_aligned(struct block_device *bdev,
|
|
unsigned int offset, unsigned int length)
|
|
{
|
|
unsigned short sector_size = bdev_logical_block_size(bdev);
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|
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if (!IS_ALIGNED(offset, sector_size))
|
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return false;
|
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if (!IS_ALIGNED(length, sector_size))
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return false;
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|
|
return true;
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}
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|
|
int __dax_zero_page_range(struct block_device *bdev, sector_t sector,
|
|
unsigned int offset, unsigned int length)
|
|
{
|
|
struct blk_dax_ctl dax = {
|
|
.sector = sector,
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|
.size = PAGE_SIZE,
|
|
};
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|
|
if (dax_range_is_aligned(bdev, offset, length)) {
|
|
sector_t start_sector = dax.sector + (offset >> 9);
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|
|
return blkdev_issue_zeroout(bdev, start_sector,
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length >> 9, GFP_NOFS, true);
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|
} else {
|
|
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;
|
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}
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EXPORT_SYMBOL_GPL(__dax_zero_page_range);
|
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|
|
/**
|
|
* 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.
|
|
*/
|
|
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_SHIFT;
|
|
unsigned offset = from & (PAGE_SIZE-1);
|
|
int err;
|
|
|
|
/* Block boundary? Nothing to do */
|
|
if (!length)
|
|
return 0;
|
|
BUG_ON((offset + length) > PAGE_SIZE);
|
|
|
|
memset(&bh, 0, sizeof(bh));
|
|
bh.b_bdev = inode->i_sb->s_bdev;
|
|
bh.b_size = PAGE_SIZE;
|
|
err = get_block(inode, index, &bh, 0);
|
|
if (err < 0 || !buffer_written(&bh))
|
|
return err;
|
|
|
|
return __dax_zero_page_range(bh.b_bdev, to_sector(&bh, inode),
|
|
offset, length);
|
|
}
|
|
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.
|
|
*/
|
|
int dax_truncate_page(struct inode *inode, loff_t from, get_block_t get_block)
|
|
{
|
|
unsigned length = PAGE_ALIGN(from) - from;
|
|
return dax_zero_page_range(inode, from, length, get_block);
|
|
}
|
|
EXPORT_SYMBOL_GPL(dax_truncate_page);
|