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![Aaron Lu](/assets/img/avatar_default.png)
The global zero page is used to satisfy an anonymous read fault. If THP(Transparent HugePage) is enabled then the global huge zero page is used. The global huge zero page uses an atomic counter for reference counting and is allocated/freed dynamically according to its counter value. CPU time spent on that counter will greatly increase if there are a lot of processes doing anonymous read faults. This patch proposes a way to reduce the access to the global counter so that the CPU load can be reduced accordingly. To do this, a new flag of the mm_struct is introduced: MMF_USED_HUGE_ZERO_PAGE. With this flag, the process only need to touch the global counter in two cases: 1 The first time it uses the global huge zero page; 2 The time when mm_user of its mm_struct reaches zero. Note that right now, the huge zero page is eligible to be freed as soon as its last use goes away. With this patch, the page will not be eligible to be freed until the exit of the last process from which it was ever used. And with the use of mm_user, the kthread is not eligible to use huge zero page either. Since no kthread is using huge zero page today, there is no difference after applying this patch. But if that is not desired, I can change it to when mm_count reaches zero. Case used for test on Haswell EP: usemem -n 72 --readonly -j 0x200000 100G Which spawns 72 processes and each will mmap 100G anonymous space and then do read only access to that space sequentially with a step of 2MB. CPU cycles from perf report for base commit: 54.03% usemem [kernel.kallsyms] [k] get_huge_zero_page CPU cycles from perf report for this commit: 0.11% usemem [kernel.kallsyms] [k] mm_get_huge_zero_page Performance(throughput) of the workload for base commit: 1784430792 Performance(throughput) of the workload for this commit: 4726928591 164% increase. Runtime of the workload for base commit: 707592 us Runtime of the workload for this commit: 303970 us 50% drop. Link: http://lkml.kernel.org/r/fe51a88f-446a-4622-1363-ad1282d71385@intel.com Signed-off-by: Aaron Lu <aaron.lu@intel.com> Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Tim Chen <tim.c.chen@linux.intel.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Jerome Marchand <jmarchan@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Ebru Akagunduz <ebru.akagunduz@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1471 lines
41 KiB
C
1471 lines
41 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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#include <linux/iomap.h>
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#include "internal.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 = 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 = 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;
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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 = 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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} 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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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. */
|
|
mapping->nrexceptional++;
|
|
spin_unlock_irq(&mapping->tree_lock);
|
|
return ret;
|
|
}
|
|
/* Normal page in radix tree? */
|
|
if (!radix_tree_exceptional_entry(ret)) {
|
|
struct page *page = ret;
|
|
|
|
get_page(page);
|
|
spin_unlock_irq(&mapping->tree_lock);
|
|
lock_page(page);
|
|
/* Page got truncated? Retry... */
|
|
if (unlikely(page->mapping != mapping)) {
|
|
unlock_page(page);
|
|
put_page(page);
|
|
goto restart;
|
|
}
|
|
return page;
|
|
}
|
|
ret = lock_slot(mapping, slot);
|
|
spin_unlock_irq(&mapping->tree_lock);
|
|
return ret;
|
|
}
|
|
|
|
void dax_wake_mapping_entry_waiter(struct address_space *mapping,
|
|
pgoff_t index, bool wake_all)
|
|
{
|
|
wait_queue_head_t *wq = dax_entry_waitqueue(mapping, index);
|
|
|
|
/*
|
|
* Checking for locked entry and prepare_to_wait_exclusive() happens
|
|
* under mapping->tree_lock, ditto for entry handling in our callers.
|
|
* 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_dax(struct block_device *bdev, sector_t sector, size_t size,
|
|
struct page *to, unsigned long vaddr)
|
|
{
|
|
struct blk_dax_ctl dax = {
|
|
.sector = sector,
|
|
.size = size,
|
|
};
|
|
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;
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(dax_writeback_mapping_range);
|
|
|
|
static int dax_insert_mapping(struct address_space *mapping,
|
|
struct block_device *bdev, sector_t sector, size_t size,
|
|
void **entryp, struct vm_area_struct *vma, struct vm_fault *vmf)
|
|
{
|
|
unsigned long vaddr = (unsigned long)vmf->virtual_address;
|
|
struct blk_dax_ctl dax = {
|
|
.sector = sector,
|
|
.size = 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_dax(bh.b_bdev, to_sector(&bh, inode),
|
|
bh.b_size, new_page, 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.b_bdev, to_sector(&bh, inode),
|
|
bh.b_size, &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_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")
|
|
|
|
/**
|
|
* 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)
|
|
{
|
|
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 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;
|
|
WARN_ON_ONCE(buffer_unwritten(&bh) || buffer_new(&bh));
|
|
}
|
|
|
|
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);
|
|
}
|
|
|
|
if (!write && !buffer_mapped(&bh)) {
|
|
spinlock_t *ptl;
|
|
pmd_t entry;
|
|
struct page *zero_page = mm_get_huge_zero_page(vma->vm_mm);
|
|
|
|
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) {
|
|
dax_pmd_dbg(&bh, address, "dax-error fallback");
|
|
goto fallback;
|
|
}
|
|
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;
|
|
}
|
|
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) {
|
|
/*
|
|
* We should insert radix-tree entry and dirty it here.
|
|
* For now this is broken...
|
|
*/
|
|
}
|
|
|
|
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:
|
|
return result;
|
|
|
|
fallback:
|
|
count_vm_event(THP_FAULT_FALLBACK);
|
|
result = VM_FAULT_FALLBACK;
|
|
goto out;
|
|
}
|
|
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;
|
|
struct address_space *mapping = file->f_mapping;
|
|
void *entry;
|
|
pgoff_t index = vmf->pgoff;
|
|
|
|
spin_lock_irq(&mapping->tree_lock);
|
|
entry = get_unlocked_mapping_entry(mapping, index, NULL);
|
|
if (!entry || !radix_tree_exceptional_entry(entry))
|
|
goto out;
|
|
radix_tree_tag_set(&mapping->page_tree, index, PAGECACHE_TAG_DIRTY);
|
|
put_unlocked_mapping_entry(mapping, index, entry);
|
|
out:
|
|
spin_unlock_irq(&mapping->tree_lock);
|
|
return VM_FAULT_NOPAGE;
|
|
}
|
|
EXPORT_SYMBOL_GPL(dax_pfn_mkwrite);
|
|
|
|
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);
|
|
|
|
if (!IS_ALIGNED(offset, sector_size))
|
|
return false;
|
|
if (!IS_ALIGNED(length, sector_size))
|
|
return false;
|
|
|
|
return true;
|
|
}
|
|
|
|
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,
|
|
.size = PAGE_SIZE,
|
|
};
|
|
|
|
if (dax_range_is_aligned(bdev, offset, length)) {
|
|
sector_t start_sector = dax.sector + (offset >> 9);
|
|
|
|
return blkdev_issue_zeroout(bdev, start_sector,
|
|
length >> 9, GFP_NOFS, true);
|
|
} else {
|
|
if (dax_map_atomic(bdev, &dax) < 0)
|
|
return PTR_ERR(dax.addr);
|
|
clear_pmem(dax.addr + offset, length);
|
|
dax_unmap_atomic(bdev, &dax);
|
|
}
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(__dax_zero_page_range);
|
|
|
|
/**
|
|
* 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);
|
|
|
|
#ifdef CONFIG_FS_IOMAP
|
|
static loff_t
|
|
iomap_dax_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
|
|
struct iomap *iomap)
|
|
{
|
|
struct iov_iter *iter = data;
|
|
loff_t end = pos + length, done = 0;
|
|
ssize_t ret = 0;
|
|
|
|
if (iov_iter_rw(iter) == READ) {
|
|
end = min(end, i_size_read(inode));
|
|
if (pos >= end)
|
|
return 0;
|
|
|
|
if (iomap->type == IOMAP_HOLE || iomap->type == IOMAP_UNWRITTEN)
|
|
return iov_iter_zero(min(length, end - pos), iter);
|
|
}
|
|
|
|
if (WARN_ON_ONCE(iomap->type != IOMAP_MAPPED))
|
|
return -EIO;
|
|
|
|
while (pos < end) {
|
|
unsigned offset = pos & (PAGE_SIZE - 1);
|
|
struct blk_dax_ctl dax = { 0 };
|
|
ssize_t map_len;
|
|
|
|
dax.sector = iomap->blkno +
|
|
(((pos & PAGE_MASK) - iomap->offset) >> 9);
|
|
dax.size = (length + offset + PAGE_SIZE - 1) & PAGE_MASK;
|
|
map_len = dax_map_atomic(iomap->bdev, &dax);
|
|
if (map_len < 0) {
|
|
ret = map_len;
|
|
break;
|
|
}
|
|
|
|
dax.addr += offset;
|
|
map_len -= offset;
|
|
if (map_len > end - pos)
|
|
map_len = end - pos;
|
|
|
|
if (iov_iter_rw(iter) == WRITE)
|
|
map_len = copy_from_iter_pmem(dax.addr, map_len, iter);
|
|
else
|
|
map_len = copy_to_iter(dax.addr, map_len, iter);
|
|
dax_unmap_atomic(iomap->bdev, &dax);
|
|
if (map_len <= 0) {
|
|
ret = map_len ? map_len : -EFAULT;
|
|
break;
|
|
}
|
|
|
|
pos += map_len;
|
|
length -= map_len;
|
|
done += map_len;
|
|
}
|
|
|
|
return done ? done : ret;
|
|
}
|
|
|
|
/**
|
|
* iomap_dax_rw - Perform I/O to a DAX file
|
|
* @iocb: The control block for this I/O
|
|
* @iter: The addresses to do I/O from or to
|
|
* @ops: iomap ops passed from the file system
|
|
*
|
|
* This function performs read and write operations to directly mapped
|
|
* persistent memory. The callers needs to take care of read/write exclusion
|
|
* and evicting any page cache pages in the region under I/O.
|
|
*/
|
|
ssize_t
|
|
iomap_dax_rw(struct kiocb *iocb, struct iov_iter *iter,
|
|
struct iomap_ops *ops)
|
|
{
|
|
struct address_space *mapping = iocb->ki_filp->f_mapping;
|
|
struct inode *inode = mapping->host;
|
|
loff_t pos = iocb->ki_pos, ret = 0, done = 0;
|
|
unsigned flags = 0;
|
|
|
|
if (iov_iter_rw(iter) == WRITE)
|
|
flags |= IOMAP_WRITE;
|
|
|
|
/*
|
|
* Yes, even DAX files can have page cache attached to them: A zeroed
|
|
* page is inserted into the pagecache when we have to serve a write
|
|
* fault on a hole. It should never be dirtied and can simply be
|
|
* dropped from the pagecache once we get real data for the page.
|
|
*
|
|
* XXX: This is racy against mmap, and there's nothing we can do about
|
|
* it. We'll eventually need to shift this down even further so that
|
|
* we can check if we allocated blocks over a hole first.
|
|
*/
|
|
if (mapping->nrpages) {
|
|
ret = invalidate_inode_pages2_range(mapping,
|
|
pos >> PAGE_SHIFT,
|
|
(pos + iov_iter_count(iter) - 1) >> PAGE_SHIFT);
|
|
WARN_ON_ONCE(ret);
|
|
}
|
|
|
|
while (iov_iter_count(iter)) {
|
|
ret = iomap_apply(inode, pos, iov_iter_count(iter), flags, ops,
|
|
iter, iomap_dax_actor);
|
|
if (ret <= 0)
|
|
break;
|
|
pos += ret;
|
|
done += ret;
|
|
}
|
|
|
|
iocb->ki_pos += done;
|
|
return done ? done : ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(iomap_dax_rw);
|
|
|
|
/**
|
|
* iomap_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
|
|
* @ops: iomap ops passed from the file system
|
|
*
|
|
* When a page fault occurs, filesystems may call this helper in their fault
|
|
* or mkwrite handler for DAX files. Assumes the caller has done all the
|
|
* necessary locking for the page fault to proceed successfully.
|
|
*/
|
|
int iomap_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
|
|
struct iomap_ops *ops)
|
|
{
|
|
struct address_space *mapping = vma->vm_file->f_mapping;
|
|
struct inode *inode = mapping->host;
|
|
unsigned long vaddr = (unsigned long)vmf->virtual_address;
|
|
loff_t pos = (loff_t)vmf->pgoff << PAGE_SHIFT;
|
|
sector_t sector;
|
|
struct iomap iomap = { 0 };
|
|
unsigned flags = 0;
|
|
int error, major = 0;
|
|
void *entry;
|
|
|
|
/*
|
|
* 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.
|
|
*/
|
|
if (pos >= i_size_read(inode))
|
|
return VM_FAULT_SIGBUS;
|
|
|
|
entry = grab_mapping_entry(mapping, vmf->pgoff);
|
|
if (IS_ERR(entry)) {
|
|
error = PTR_ERR(entry);
|
|
goto out;
|
|
}
|
|
|
|
if ((vmf->flags & FAULT_FLAG_WRITE) && !vmf->cow_page)
|
|
flags |= IOMAP_WRITE;
|
|
|
|
/*
|
|
* Note that we don't bother to use iomap_apply here: DAX required
|
|
* the file system block size to be equal the page size, which means
|
|
* that we never have to deal with more than a single extent here.
|
|
*/
|
|
error = ops->iomap_begin(inode, pos, PAGE_SIZE, flags, &iomap);
|
|
if (error)
|
|
goto unlock_entry;
|
|
if (WARN_ON_ONCE(iomap.offset + iomap.length < pos + PAGE_SIZE)) {
|
|
error = -EIO; /* fs corruption? */
|
|
goto unlock_entry;
|
|
}
|
|
|
|
sector = iomap.blkno + (((pos & PAGE_MASK) - iomap.offset) >> 9);
|
|
|
|
if (vmf->cow_page) {
|
|
switch (iomap.type) {
|
|
case IOMAP_HOLE:
|
|
case IOMAP_UNWRITTEN:
|
|
clear_user_highpage(vmf->cow_page, vaddr);
|
|
break;
|
|
case IOMAP_MAPPED:
|
|
error = copy_user_dax(iomap.bdev, sector, PAGE_SIZE,
|
|
vmf->cow_page, vaddr);
|
|
break;
|
|
default:
|
|
WARN_ON_ONCE(1);
|
|
error = -EIO;
|
|
break;
|
|
}
|
|
|
|
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;
|
|
}
|
|
|
|
switch (iomap.type) {
|
|
case IOMAP_MAPPED:
|
|
if (iomap.flags & IOMAP_F_NEW) {
|
|
count_vm_event(PGMAJFAULT);
|
|
mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT);
|
|
major = VM_FAULT_MAJOR;
|
|
}
|
|
error = dax_insert_mapping(mapping, iomap.bdev, sector,
|
|
PAGE_SIZE, &entry, vma, vmf);
|
|
break;
|
|
case IOMAP_UNWRITTEN:
|
|
case IOMAP_HOLE:
|
|
if (!(vmf->flags & FAULT_FLAG_WRITE))
|
|
return dax_load_hole(mapping, entry, vmf);
|
|
/*FALLTHRU*/
|
|
default:
|
|
WARN_ON_ONCE(1);
|
|
error = -EIO;
|
|
break;
|
|
}
|
|
|
|
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_GPL(iomap_dax_fault);
|
|
#endif /* CONFIG_FS_IOMAP */
|