![Michal Hocko](/assets/img/avatar_default.png)
Tetsuo has noticed that an OOM stress test which performs large write
requests can cause the full memory reserves depletion. He has tracked
this down to the following path
__alloc_pages_nodemask+0x436/0x4d0
alloc_pages_current+0x97/0x1b0
__page_cache_alloc+0x15d/0x1a0 mm/filemap.c:728
pagecache_get_page+0x5a/0x2b0 mm/filemap.c:1331
grab_cache_page_write_begin+0x23/0x40 mm/filemap.c:2773
iomap_write_begin+0x50/0xd0 fs/iomap.c:118
iomap_write_actor+0xb5/0x1a0 fs/iomap.c:190
? iomap_write_end+0x80/0x80 fs/iomap.c:150
iomap_apply+0xb3/0x130 fs/iomap.c:79
iomap_file_buffered_write+0x68/0xa0 fs/iomap.c:243
? iomap_write_end+0x80/0x80
xfs_file_buffered_aio_write+0x132/0x390 [xfs]
? remove_wait_queue+0x59/0x60
xfs_file_write_iter+0x90/0x130 [xfs]
__vfs_write+0xe5/0x140
vfs_write+0xc7/0x1f0
? syscall_trace_enter+0x1d0/0x380
SyS_write+0x58/0xc0
do_syscall_64+0x6c/0x200
entry_SYSCALL64_slow_path+0x25/0x25
the oom victim has access to all memory reserves to make a forward
progress to exit easier. But iomap_file_buffered_write and other
callers of iomap_apply loop to complete the full request. We need to
check for fatal signals and back off with a short write instead.
As the iomap_apply delegates all the work down to the actor we have to
hook into those. All callers that work with the page cache are calling
iomap_write_begin so we will check for signals there. dax_iomap_actor
has to handle the situation explicitly because it copies data to the
userspace directly. Other callers like iomap_page_mkwrite work on a
single page or iomap_fiemap_actor do not allocate memory based on the
given len.
Fixes: 68a9f5e700
("xfs: implement iomap based buffered write path")
Link: http://lkml.kernel.org/r/20170201092706.9966-2-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: <stable@vger.kernel.org> [4.8+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1435 lines
40 KiB
C
1435 lines
40 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/mmu_notifier.h>
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#include <linux/iomap.h>
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#include "internal.h"
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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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static 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 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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static int dax_is_pmd_entry(void *entry)
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{
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return (unsigned long)entry & RADIX_DAX_PMD;
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}
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static int dax_is_pte_entry(void *entry)
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{
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return !((unsigned long)entry & RADIX_DAX_PMD);
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}
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static int dax_is_zero_entry(void *entry)
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{
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return (unsigned long)entry & RADIX_DAX_HZP;
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}
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static int dax_is_empty_entry(void *entry)
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{
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return (unsigned long)entry & RADIX_DAX_EMPTY;
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}
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struct page *read_dax_sector(struct block_device *bdev, sector_t n)
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{
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struct page *page = alloc_pages(GFP_KERNEL, 0);
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struct blk_dax_ctl dax = {
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.size = PAGE_SIZE,
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.sector = n & ~((((int) PAGE_SIZE) / 512) - 1),
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};
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long rc;
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if (!page)
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return ERR_PTR(-ENOMEM);
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rc = dax_map_atomic(bdev, &dax);
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if (rc < 0)
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return ERR_PTR(rc);
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memcpy_from_pmem(page_address(page), dax.addr, PAGE_SIZE);
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dax_unmap_atomic(bdev, &dax);
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return page;
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}
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/*
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* DAX 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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pgoff_t entry_start;
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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 wait_queue_head_t *dax_entry_waitqueue(struct address_space *mapping,
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pgoff_t index, void *entry, struct exceptional_entry_key *key)
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{
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unsigned long hash;
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/*
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* If 'entry' is a PMD, align the 'index' that we use for the wait
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* queue to the start of that PMD. This ensures that all offsets in
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* the range covered by the PMD map to the same bit lock.
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*/
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if (dax_is_pmd_entry(entry))
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index &= ~((1UL << (PMD_SHIFT - PAGE_SHIFT)) - 1);
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key->mapping = mapping;
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key->entry_start = index;
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hash = hash_long((unsigned long)mapping ^ index, DAX_WAIT_TABLE_BITS);
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return wait_table + hash;
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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->entry_start != ewait->key.entry_start)
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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(&mapping->page_tree, 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(&mapping->page_tree, 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 *entry, **slot;
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struct wait_exceptional_entry_queue ewait;
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wait_queue_head_t *wq;
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init_wait(&ewait.wait);
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ewait.wait.func = wake_exceptional_entry_func;
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for (;;) {
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entry = __radix_tree_lookup(&mapping->page_tree, index, NULL,
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&slot);
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if (!entry || !radix_tree_exceptional_entry(entry) ||
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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 entry;
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}
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wq = dax_entry_waitqueue(mapping, index, entry, &ewait.key);
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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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static void dax_unlock_mapping_entry(struct address_space *mapping,
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pgoff_t index)
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{
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void *entry, **slot;
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spin_lock_irq(&mapping->tree_lock);
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entry = __radix_tree_lookup(&mapping->page_tree, index, NULL, &slot);
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if (WARN_ON_ONCE(!entry || !radix_tree_exceptional_entry(entry) ||
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!slot_locked(mapping, slot))) {
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spin_unlock_irq(&mapping->tree_lock);
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return;
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}
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unlock_slot(mapping, slot);
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spin_unlock_irq(&mapping->tree_lock);
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dax_wake_mapping_entry_waiter(mapping, index, entry, false);
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}
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static void put_locked_mapping_entry(struct address_space *mapping,
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pgoff_t index, void *entry)
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{
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if (!radix_tree_exceptional_entry(entry)) {
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unlock_page(entry);
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put_page(entry);
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} else {
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dax_unlock_mapping_entry(mapping, index);
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}
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}
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/*
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* Called when we are done with radix tree entry we looked up via
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* get_unlocked_mapping_entry() and which we didn't lock in the end.
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*/
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static void put_unlocked_mapping_entry(struct address_space *mapping,
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pgoff_t index, void *entry)
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{
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if (!radix_tree_exceptional_entry(entry))
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return;
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/* We have to wake up next waiter for the radix tree entry lock */
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dax_wake_mapping_entry_waiter(mapping, index, entry, false);
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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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* When requesting an entry with size RADIX_DAX_PMD, grab_mapping_entry() will
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* either return that locked entry or will return an error. This error will
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* happen if there are any 4k entries (either zero pages or DAX entries)
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* within the 2MiB range that we are requesting.
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*
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* We always favor 4k entries over 2MiB entries. There isn't a flow where we
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* evict 4k entries in order to 'upgrade' them to a 2MiB entry. A 2MiB
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* insertion will fail if it finds any 4k entries already in the tree, and a
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* 4k insertion will cause an existing 2MiB entry to be unmapped and
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* downgraded to 4k entries. This happens for both 2MiB huge zero pages as
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* well as 2MiB empty entries.
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*
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* The exception to this downgrade path is for 2MiB DAX PMD entries that have
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* real storage backing them. We will leave these real 2MiB DAX entries in
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* the tree, and PTE writes will simply dirty the entire 2MiB DAX entry.
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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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unsigned long size_flag)
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{
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bool pmd_downgrade = false; /* splitting 2MiB entry into 4k entries? */
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void *entry, **slot;
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restart:
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spin_lock_irq(&mapping->tree_lock);
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entry = get_unlocked_mapping_entry(mapping, index, &slot);
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if (entry) {
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if (size_flag & RADIX_DAX_PMD) {
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if (!radix_tree_exceptional_entry(entry) ||
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dax_is_pte_entry(entry)) {
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put_unlocked_mapping_entry(mapping, index,
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entry);
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entry = ERR_PTR(-EEXIST);
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goto out_unlock;
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}
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} else { /* trying to grab a PTE entry */
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if (radix_tree_exceptional_entry(entry) &&
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dax_is_pmd_entry(entry) &&
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(dax_is_zero_entry(entry) ||
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dax_is_empty_entry(entry))) {
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pmd_downgrade = true;
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}
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}
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}
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/* No entry for given index? Make sure radix tree is big enough. */
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if (!entry || pmd_downgrade) {
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int err;
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if (pmd_downgrade) {
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/*
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* Make sure 'entry' remains valid while we drop
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* mapping->tree_lock.
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*/
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entry = lock_slot(mapping, slot);
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}
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spin_unlock_irq(&mapping->tree_lock);
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/*
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* Besides huge zero pages the only other thing that gets
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* downgraded are empty entries which don't need to be
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* unmapped.
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*/
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if (pmd_downgrade && dax_is_zero_entry(entry))
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unmap_mapping_range(mapping,
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(index << PAGE_SHIFT) & PMD_MASK, PMD_SIZE, 0);
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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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if (pmd_downgrade)
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put_locked_mapping_entry(mapping, index, entry);
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return ERR_PTR(err);
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}
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spin_lock_irq(&mapping->tree_lock);
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if (pmd_downgrade) {
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radix_tree_delete(&mapping->page_tree, index);
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mapping->nrexceptional--;
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dax_wake_mapping_entry_waiter(mapping, index, entry,
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true);
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}
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entry = dax_radix_locked_entry(0, size_flag | RADIX_DAX_EMPTY);
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err = __radix_tree_insert(&mapping->page_tree, index,
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dax_radix_order(entry), entry);
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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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/*
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* Someone already created the entry? This is a
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* normal failure when inserting PMDs in a range
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* that already contains PTEs. In that case we want
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* to return -EEXIST immediately.
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*/
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if (err == -EEXIST && !(size_flag & RADIX_DAX_PMD))
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goto restart;
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/*
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* Our insertion of a DAX PMD entry failed, most
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* likely because it collided with a PTE sized entry
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* at a different index in the PMD range. We haven't
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* inserted anything into the radix tree and have no
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* waiters to wake.
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*/
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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 entry;
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}
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/* Normal page in radix tree? */
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if (!radix_tree_exceptional_entry(entry)) {
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struct page *page = entry;
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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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entry = lock_slot(mapping, slot);
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out_unlock:
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spin_unlock_irq(&mapping->tree_lock);
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return entry;
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}
|
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|
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/*
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* We do not necessarily hold the mapping->tree_lock when we call this
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* function so it is possible that 'entry' is no longer a valid item in the
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* radix tree. This is okay because all we really need to do is to find the
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* correct waitqueue where tasks might be waiting for that old 'entry' and
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* wake them.
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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, void *entry, bool wake_all)
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{
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struct exceptional_entry_key key;
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wait_queue_head_t *wq;
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wq = dax_entry_waitqueue(mapping, index, entry, &key);
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|
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/*
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* 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))
|
|
__wake_up(wq, TASK_NORMAL, wake_all ? 0 : 1, &key);
|
|
}
|
|
|
|
static int __dax_invalidate_mapping_entry(struct address_space *mapping,
|
|
pgoff_t index, bool trunc)
|
|
{
|
|
int ret = 0;
|
|
void *entry;
|
|
struct radix_tree_root *page_tree = &mapping->page_tree;
|
|
|
|
spin_lock_irq(&mapping->tree_lock);
|
|
entry = get_unlocked_mapping_entry(mapping, index, NULL);
|
|
if (!entry || !radix_tree_exceptional_entry(entry))
|
|
goto out;
|
|
if (!trunc &&
|
|
(radix_tree_tag_get(page_tree, index, PAGECACHE_TAG_DIRTY) ||
|
|
radix_tree_tag_get(page_tree, index, PAGECACHE_TAG_TOWRITE)))
|
|
goto out;
|
|
radix_tree_delete(page_tree, index);
|
|
mapping->nrexceptional--;
|
|
ret = 1;
|
|
out:
|
|
put_unlocked_mapping_entry(mapping, index, entry);
|
|
spin_unlock_irq(&mapping->tree_lock);
|
|
return ret;
|
|
}
|
|
/*
|
|
* 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)
|
|
{
|
|
int ret = __dax_invalidate_mapping_entry(mapping, index, true);
|
|
|
|
/*
|
|
* 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...
|
|
*/
|
|
WARN_ON_ONCE(!ret);
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Invalidate exceptional DAX entry if easily possible. This handles DAX
|
|
* entries for invalidate_inode_pages() so we evict the entry only if we can
|
|
* do so without blocking.
|
|
*/
|
|
int dax_invalidate_mapping_entry(struct address_space *mapping, pgoff_t index)
|
|
{
|
|
int ret = 0;
|
|
void *entry, **slot;
|
|
struct radix_tree_root *page_tree = &mapping->page_tree;
|
|
|
|
spin_lock_irq(&mapping->tree_lock);
|
|
entry = __radix_tree_lookup(page_tree, index, NULL, &slot);
|
|
if (!entry || !radix_tree_exceptional_entry(entry) ||
|
|
slot_locked(mapping, slot))
|
|
goto out;
|
|
if (radix_tree_tag_get(page_tree, index, PAGECACHE_TAG_DIRTY) ||
|
|
radix_tree_tag_get(page_tree, index, PAGECACHE_TAG_TOWRITE))
|
|
goto out;
|
|
radix_tree_delete(page_tree, index);
|
|
mapping->nrexceptional--;
|
|
ret = 1;
|
|
out:
|
|
spin_unlock_irq(&mapping->tree_lock);
|
|
if (ret)
|
|
dax_wake_mapping_entry_waiter(mapping, index, entry, true);
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Invalidate exceptional DAX entry if it is clean.
|
|
*/
|
|
int dax_invalidate_mapping_entry_sync(struct address_space *mapping,
|
|
pgoff_t index)
|
|
{
|
|
return __dax_invalidate_mapping_entry(mapping, index, false);
|
|
}
|
|
|
|
/*
|
|
* 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;
|
|
int ret;
|
|
|
|
/* Hole page already exists? Return it... */
|
|
if (!radix_tree_exceptional_entry(*entry)) {
|
|
page = *entry;
|
|
goto out;
|
|
}
|
|
|
|
/* 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)
|
|
return VM_FAULT_OOM;
|
|
out:
|
|
vmf->page = page;
|
|
ret = finish_fault(vmf);
|
|
vmf->page = NULL;
|
|
*entry = page;
|
|
if (!ret) {
|
|
/* Grab reference for PTE that is now referencing the page */
|
|
get_page(page);
|
|
return VM_FAULT_NOPAGE;
|
|
}
|
|
return ret;
|
|
}
|
|
|
|
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;
|
|
}
|
|
|
|
/*
|
|
* By this point grab_mapping_entry() has ensured that we have a locked entry
|
|
* of the appropriate size so we don't have to worry about downgrading PMDs to
|
|
* PTEs. If we happen to be trying to insert a PTE and there is a PMD
|
|
* already in the tree, we will skip the insertion and just dirty the PMD as
|
|
* appropriate.
|
|
*/
|
|
static void *dax_insert_mapping_entry(struct address_space *mapping,
|
|
struct vm_fault *vmf,
|
|
void *entry, sector_t sector,
|
|
unsigned long flags)
|
|
{
|
|
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);
|
|
} else if (dax_is_zero_entry(entry) && !(flags & RADIX_DAX_HZP)) {
|
|
/* replacing huge zero page with PMD block mapping */
|
|
unmap_mapping_range(mapping,
|
|
(vmf->pgoff << PAGE_SHIFT) & PMD_MASK, PMD_SIZE, 0);
|
|
}
|
|
|
|
spin_lock_irq(&mapping->tree_lock);
|
|
new_entry = dax_radix_locked_entry(sector, flags);
|
|
|
|
if (hole_fill) {
|
|
__delete_from_page_cache(entry, NULL);
|
|
/* Drop pagecache reference */
|
|
put_page(entry);
|
|
error = __radix_tree_insert(page_tree, index,
|
|
dax_radix_order(new_entry), new_entry);
|
|
if (error) {
|
|
new_entry = ERR_PTR(error);
|
|
goto unlock;
|
|
}
|
|
mapping->nrexceptional++;
|
|
} else if (dax_is_zero_entry(entry) || dax_is_empty_entry(entry)) {
|
|
/*
|
|
* Only swap our new entry into the radix tree if the current
|
|
* entry is a zero page or an empty entry. If a normal PTE or
|
|
* PMD entry is already in the tree, we leave it alone. This
|
|
* means that if we are trying to insert a PTE and the
|
|
* existing entry is a PMD, we will just leave the PMD in the
|
|
* tree and dirty it if necessary.
|
|
*/
|
|
struct radix_tree_node *node;
|
|
void **slot;
|
|
void *ret;
|
|
|
|
ret = __radix_tree_lookup(page_tree, index, &node, &slot);
|
|
WARN_ON_ONCE(ret != entry);
|
|
__radix_tree_replace(page_tree, node, slot,
|
|
new_entry, NULL, NULL);
|
|
}
|
|
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 inline unsigned long
|
|
pgoff_address(pgoff_t pgoff, struct vm_area_struct *vma)
|
|
{
|
|
unsigned long address;
|
|
|
|
address = vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT);
|
|
VM_BUG_ON_VMA(address < vma->vm_start || address >= vma->vm_end, vma);
|
|
return address;
|
|
}
|
|
|
|
/* Walk all mappings of a given index of a file and writeprotect them */
|
|
static void dax_mapping_entry_mkclean(struct address_space *mapping,
|
|
pgoff_t index, unsigned long pfn)
|
|
{
|
|
struct vm_area_struct *vma;
|
|
pte_t pte, *ptep = NULL;
|
|
pmd_t *pmdp = NULL;
|
|
spinlock_t *ptl;
|
|
bool changed;
|
|
|
|
i_mmap_lock_read(mapping);
|
|
vma_interval_tree_foreach(vma, &mapping->i_mmap, index, index) {
|
|
unsigned long address;
|
|
|
|
cond_resched();
|
|
|
|
if (!(vma->vm_flags & VM_SHARED))
|
|
continue;
|
|
|
|
address = pgoff_address(index, vma);
|
|
changed = false;
|
|
if (follow_pte_pmd(vma->vm_mm, address, &ptep, &pmdp, &ptl))
|
|
continue;
|
|
|
|
if (pmdp) {
|
|
#ifdef CONFIG_FS_DAX_PMD
|
|
pmd_t pmd;
|
|
|
|
if (pfn != pmd_pfn(*pmdp))
|
|
goto unlock_pmd;
|
|
if (!pmd_dirty(*pmdp) && !pmd_write(*pmdp))
|
|
goto unlock_pmd;
|
|
|
|
flush_cache_page(vma, address, pfn);
|
|
pmd = pmdp_huge_clear_flush(vma, address, pmdp);
|
|
pmd = pmd_wrprotect(pmd);
|
|
pmd = pmd_mkclean(pmd);
|
|
set_pmd_at(vma->vm_mm, address, pmdp, pmd);
|
|
changed = true;
|
|
unlock_pmd:
|
|
spin_unlock(ptl);
|
|
#endif
|
|
} else {
|
|
if (pfn != pte_pfn(*ptep))
|
|
goto unlock_pte;
|
|
if (!pte_dirty(*ptep) && !pte_write(*ptep))
|
|
goto unlock_pte;
|
|
|
|
flush_cache_page(vma, address, pfn);
|
|
pte = ptep_clear_flush(vma, address, ptep);
|
|
pte = pte_wrprotect(pte);
|
|
pte = pte_mkclean(pte);
|
|
set_pte_at(vma->vm_mm, address, ptep, pte);
|
|
changed = true;
|
|
unlock_pte:
|
|
pte_unmap_unlock(ptep, ptl);
|
|
}
|
|
|
|
if (changed)
|
|
mmu_notifier_invalidate_page(vma->vm_mm, address);
|
|
}
|
|
i_mmap_unlock_read(mapping);
|
|
}
|
|
|
|
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;
|
|
struct blk_dax_ctl dax;
|
|
void *entry2, **slot;
|
|
int ret = 0;
|
|
|
|
/*
|
|
* A page got tagged dirty in DAX mapping? Something is seriously
|
|
* wrong.
|
|
*/
|
|
if (WARN_ON(!radix_tree_exceptional_entry(entry)))
|
|
return -EIO;
|
|
|
|
spin_lock_irq(&mapping->tree_lock);
|
|
entry2 = get_unlocked_mapping_entry(mapping, index, &slot);
|
|
/* Entry got punched out / reallocated? */
|
|
if (!entry2 || !radix_tree_exceptional_entry(entry2))
|
|
goto put_unlocked;
|
|
/*
|
|
* Entry got reallocated elsewhere? No need to writeback. We have to
|
|
* compare sectors as we must not bail out due to difference in lockbit
|
|
* or entry type.
|
|
*/
|
|
if (dax_radix_sector(entry2) != dax_radix_sector(entry))
|
|
goto put_unlocked;
|
|
if (WARN_ON_ONCE(dax_is_empty_entry(entry) ||
|
|
dax_is_zero_entry(entry))) {
|
|
ret = -EIO;
|
|
goto put_unlocked;
|
|
}
|
|
|
|
/* Another fsync thread may have already written back this entry */
|
|
if (!radix_tree_tag_get(page_tree, index, PAGECACHE_TAG_TOWRITE))
|
|
goto put_unlocked;
|
|
/* Lock the entry to serialize with page faults */
|
|
entry = lock_slot(mapping, slot);
|
|
/*
|
|
* We can clear the tag now but we have to be careful so that concurrent
|
|
* dax_writeback_one() calls for the same index cannot finish before we
|
|
* actually flush the caches. This is achieved as the calls will look
|
|
* at the entry only under tree_lock and once they do that they will
|
|
* see the entry locked and wait for it to unlock.
|
|
*/
|
|
radix_tree_tag_clear(page_tree, index, PAGECACHE_TAG_TOWRITE);
|
|
spin_unlock_irq(&mapping->tree_lock);
|
|
|
|
/*
|
|
* Even if dax_writeback_mapping_range() was given a wbc->range_start
|
|
* in the middle of a PMD, the 'index' we are given will be aligned to
|
|
* the start index of the PMD, as will the sector we pull from
|
|
* 'entry'. This allows us to flush for PMD_SIZE and not have to
|
|
* worry about partial PMD writebacks.
|
|
*/
|
|
dax.sector = dax_radix_sector(entry);
|
|
dax.size = PAGE_SIZE << dax_radix_order(entry);
|
|
|
|
/*
|
|
* 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) {
|
|
put_locked_mapping_entry(mapping, index, entry);
|
|
return ret;
|
|
}
|
|
|
|
if (WARN_ON_ONCE(ret < dax.size)) {
|
|
ret = -EIO;
|
|
goto unmap;
|
|
}
|
|
|
|
dax_mapping_entry_mkclean(mapping, index, pfn_t_to_pfn(dax.pfn));
|
|
wb_cache_pmem(dax.addr, dax.size);
|
|
/*
|
|
* After we have flushed the cache, we can clear the dirty tag. There
|
|
* cannot be new dirty data in the pfn after the flush has completed as
|
|
* the pfn mappings are writeprotected and fault waits for mapping
|
|
* entry lock.
|
|
*/
|
|
spin_lock_irq(&mapping->tree_lock);
|
|
radix_tree_tag_clear(page_tree, index, PAGECACHE_TAG_DIRTY);
|
|
spin_unlock_irq(&mapping->tree_lock);
|
|
unmap:
|
|
dax_unmap_atomic(bdev, &dax);
|
|
put_locked_mapping_entry(mapping, index, entry);
|
|
return ret;
|
|
|
|
put_unlocked:
|
|
put_unlocked_mapping_entry(mapping, index, entry2);
|
|
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;
|
|
pgoff_t indices[PAGEVEC_SIZE];
|
|
struct pagevec pvec;
|
|
bool done = false;
|
|
int i, ret = 0;
|
|
|
|
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;
|
|
|
|
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 = vmf->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, 0);
|
|
if (IS_ERR(ret))
|
|
return PTR_ERR(ret);
|
|
*entryp = ret;
|
|
|
|
return vm_insert_mixed(vma, vaddr, dax.pfn);
|
|
}
|
|
|
|
/**
|
|
* 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, **slot;
|
|
pgoff_t index = vmf->pgoff;
|
|
|
|
spin_lock_irq(&mapping->tree_lock);
|
|
entry = get_unlocked_mapping_entry(mapping, index, &slot);
|
|
if (!entry || !radix_tree_exceptional_entry(entry)) {
|
|
if (entry)
|
|
put_unlocked_mapping_entry(mapping, index, entry);
|
|
spin_unlock_irq(&mapping->tree_lock);
|
|
return VM_FAULT_NOPAGE;
|
|
}
|
|
radix_tree_tag_set(&mapping->page_tree, index, PAGECACHE_TAG_DIRTY);
|
|
entry = lock_slot(mapping, slot);
|
|
spin_unlock_irq(&mapping->tree_lock);
|
|
/*
|
|
* If we race with somebody updating the PTE and finish_mkwrite_fault()
|
|
* fails, we don't care. We need to return VM_FAULT_NOPAGE and retry
|
|
* the fault in either case.
|
|
*/
|
|
finish_mkwrite_fault(vmf);
|
|
put_locked_mapping_entry(mapping, index, entry);
|
|
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);
|
|
|
|
static sector_t dax_iomap_sector(struct iomap *iomap, loff_t pos)
|
|
{
|
|
return iomap->blkno + (((pos & PAGE_MASK) - iomap->offset) >> 9);
|
|
}
|
|
|
|
static loff_t
|
|
dax_iomap_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;
|
|
|
|
/*
|
|
* Write can allocate block for an area which has a hole page mapped
|
|
* into page tables. We have to tear down these mappings so that data
|
|
* written by write(2) is visible in mmap.
|
|
*/
|
|
if ((iomap->flags & IOMAP_F_NEW) && inode->i_mapping->nrpages) {
|
|
invalidate_inode_pages2_range(inode->i_mapping,
|
|
pos >> PAGE_SHIFT,
|
|
(end - 1) >> PAGE_SHIFT);
|
|
}
|
|
|
|
while (pos < end) {
|
|
unsigned offset = pos & (PAGE_SIZE - 1);
|
|
struct blk_dax_ctl dax = { 0 };
|
|
ssize_t map_len;
|
|
|
|
if (fatal_signal_pending(current)) {
|
|
ret = -EINTR;
|
|
break;
|
|
}
|
|
|
|
dax.sector = dax_iomap_sector(iomap, pos);
|
|
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;
|
|
}
|
|
|
|
/**
|
|
* dax_iomap_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
|
|
dax_iomap_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;
|
|
|
|
while (iov_iter_count(iter)) {
|
|
ret = iomap_apply(inode, pos, iov_iter_count(iter), flags, ops,
|
|
iter, dax_iomap_actor);
|
|
if (ret <= 0)
|
|
break;
|
|
pos += ret;
|
|
done += ret;
|
|
}
|
|
|
|
iocb->ki_pos += done;
|
|
return done ? done : ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(dax_iomap_rw);
|
|
|
|
static int dax_fault_return(int error)
|
|
{
|
|
if (error == 0)
|
|
return VM_FAULT_NOPAGE;
|
|
if (error == -ENOMEM)
|
|
return VM_FAULT_OOM;
|
|
return VM_FAULT_SIGBUS;
|
|
}
|
|
|
|
/**
|
|
* dax_iomap_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 dax_iomap_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 = vmf->address;
|
|
loff_t pos = (loff_t)vmf->pgoff << PAGE_SHIFT;
|
|
sector_t sector;
|
|
struct iomap iomap = { 0 };
|
|
unsigned flags = IOMAP_FAULT;
|
|
int error, major = 0;
|
|
int vmf_ret = 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;
|
|
|
|
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)
|
|
return dax_fault_return(error);
|
|
if (WARN_ON_ONCE(iomap.offset + iomap.length < pos + PAGE_SIZE)) {
|
|
vmf_ret = dax_fault_return(-EIO); /* fs corruption? */
|
|
goto finish_iomap;
|
|
}
|
|
|
|
entry = grab_mapping_entry(mapping, vmf->pgoff, 0);
|
|
if (IS_ERR(entry)) {
|
|
vmf_ret = dax_fault_return(PTR_ERR(entry));
|
|
goto finish_iomap;
|
|
}
|
|
|
|
sector = dax_iomap_sector(&iomap, pos);
|
|
|
|
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 error_unlock_entry;
|
|
|
|
__SetPageUptodate(vmf->cow_page);
|
|
vmf_ret = finish_fault(vmf);
|
|
if (!vmf_ret)
|
|
vmf_ret = VM_FAULT_DONE_COW;
|
|
goto unlock_entry;
|
|
}
|
|
|
|
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);
|
|
/* -EBUSY is fine, somebody else faulted on the same PTE */
|
|
if (error == -EBUSY)
|
|
error = 0;
|
|
break;
|
|
case IOMAP_UNWRITTEN:
|
|
case IOMAP_HOLE:
|
|
if (!(vmf->flags & FAULT_FLAG_WRITE)) {
|
|
vmf_ret = dax_load_hole(mapping, &entry, vmf);
|
|
goto unlock_entry;
|
|
}
|
|
/*FALLTHRU*/
|
|
default:
|
|
WARN_ON_ONCE(1);
|
|
error = -EIO;
|
|
break;
|
|
}
|
|
|
|
error_unlock_entry:
|
|
vmf_ret = dax_fault_return(error) | major;
|
|
unlock_entry:
|
|
put_locked_mapping_entry(mapping, vmf->pgoff, entry);
|
|
finish_iomap:
|
|
if (ops->iomap_end) {
|
|
int copied = PAGE_SIZE;
|
|
|
|
if (vmf_ret & VM_FAULT_ERROR)
|
|
copied = 0;
|
|
/*
|
|
* The fault is done by now and there's no way back (other
|
|
* thread may be already happily using PTE we have installed).
|
|
* Just ignore error from ->iomap_end since we cannot do much
|
|
* with it.
|
|
*/
|
|
ops->iomap_end(inode, pos, PAGE_SIZE, copied, flags, &iomap);
|
|
}
|
|
return vmf_ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(dax_iomap_fault);
|
|
|
|
#ifdef CONFIG_FS_DAX_PMD
|
|
/*
|
|
* The 'colour' (ie low bits) within a PMD of a page offset. This comes up
|
|
* more often than one might expect in the below functions.
|
|
*/
|
|
#define PG_PMD_COLOUR ((PMD_SIZE >> PAGE_SHIFT) - 1)
|
|
|
|
static int dax_pmd_insert_mapping(struct vm_area_struct *vma, pmd_t *pmd,
|
|
struct vm_fault *vmf, unsigned long address,
|
|
struct iomap *iomap, loff_t pos, bool write, void **entryp)
|
|
{
|
|
struct address_space *mapping = vma->vm_file->f_mapping;
|
|
struct block_device *bdev = iomap->bdev;
|
|
struct blk_dax_ctl dax = {
|
|
.sector = dax_iomap_sector(iomap, pos),
|
|
.size = PMD_SIZE,
|
|
};
|
|
long length = dax_map_atomic(bdev, &dax);
|
|
void *ret;
|
|
|
|
if (length < 0) /* dax_map_atomic() failed */
|
|
return VM_FAULT_FALLBACK;
|
|
if (length < PMD_SIZE)
|
|
goto unmap_fallback;
|
|
if (pfn_t_to_pfn(dax.pfn) & PG_PMD_COLOUR)
|
|
goto unmap_fallback;
|
|
if (!pfn_t_devmap(dax.pfn))
|
|
goto unmap_fallback;
|
|
|
|
dax_unmap_atomic(bdev, &dax);
|
|
|
|
ret = dax_insert_mapping_entry(mapping, vmf, *entryp, dax.sector,
|
|
RADIX_DAX_PMD);
|
|
if (IS_ERR(ret))
|
|
return VM_FAULT_FALLBACK;
|
|
*entryp = ret;
|
|
|
|
return vmf_insert_pfn_pmd(vma, address, pmd, dax.pfn, write);
|
|
|
|
unmap_fallback:
|
|
dax_unmap_atomic(bdev, &dax);
|
|
return VM_FAULT_FALLBACK;
|
|
}
|
|
|
|
static int dax_pmd_load_hole(struct vm_area_struct *vma, pmd_t *pmd,
|
|
struct vm_fault *vmf, unsigned long address,
|
|
struct iomap *iomap, void **entryp)
|
|
{
|
|
struct address_space *mapping = vma->vm_file->f_mapping;
|
|
unsigned long pmd_addr = address & PMD_MASK;
|
|
struct page *zero_page;
|
|
spinlock_t *ptl;
|
|
pmd_t pmd_entry;
|
|
void *ret;
|
|
|
|
zero_page = mm_get_huge_zero_page(vma->vm_mm);
|
|
|
|
if (unlikely(!zero_page))
|
|
return VM_FAULT_FALLBACK;
|
|
|
|
ret = dax_insert_mapping_entry(mapping, vmf, *entryp, 0,
|
|
RADIX_DAX_PMD | RADIX_DAX_HZP);
|
|
if (IS_ERR(ret))
|
|
return VM_FAULT_FALLBACK;
|
|
*entryp = ret;
|
|
|
|
ptl = pmd_lock(vma->vm_mm, pmd);
|
|
if (!pmd_none(*pmd)) {
|
|
spin_unlock(ptl);
|
|
return VM_FAULT_FALLBACK;
|
|
}
|
|
|
|
pmd_entry = mk_pmd(zero_page, vma->vm_page_prot);
|
|
pmd_entry = pmd_mkhuge(pmd_entry);
|
|
set_pmd_at(vma->vm_mm, pmd_addr, pmd, pmd_entry);
|
|
spin_unlock(ptl);
|
|
return VM_FAULT_NOPAGE;
|
|
}
|
|
|
|
int dax_iomap_pmd_fault(struct vm_area_struct *vma, unsigned long address,
|
|
pmd_t *pmd, unsigned int flags, struct iomap_ops *ops)
|
|
{
|
|
struct address_space *mapping = vma->vm_file->f_mapping;
|
|
unsigned long pmd_addr = address & PMD_MASK;
|
|
bool write = flags & FAULT_FLAG_WRITE;
|
|
unsigned int iomap_flags = (write ? IOMAP_WRITE : 0) | IOMAP_FAULT;
|
|
struct inode *inode = mapping->host;
|
|
int result = VM_FAULT_FALLBACK;
|
|
struct iomap iomap = { 0 };
|
|
pgoff_t max_pgoff, pgoff;
|
|
struct vm_fault vmf;
|
|
void *entry;
|
|
loff_t pos;
|
|
int error;
|
|
|
|
/* Fall back to PTEs if we're going to COW */
|
|
if (write && !(vma->vm_flags & VM_SHARED))
|
|
goto fallback;
|
|
|
|
/* If the PMD would extend outside the VMA */
|
|
if (pmd_addr < vma->vm_start)
|
|
goto fallback;
|
|
if ((pmd_addr + PMD_SIZE) > vma->vm_end)
|
|
goto fallback;
|
|
|
|
/*
|
|
* 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.
|
|
*/
|
|
pgoff = linear_page_index(vma, pmd_addr);
|
|
max_pgoff = (i_size_read(inode) - 1) >> PAGE_SHIFT;
|
|
|
|
if (pgoff > max_pgoff)
|
|
return VM_FAULT_SIGBUS;
|
|
|
|
/* If the PMD would extend beyond the file size */
|
|
if ((pgoff | PG_PMD_COLOUR) > max_pgoff)
|
|
goto fallback;
|
|
|
|
/*
|
|
* Note that we don't use iomap_apply here. We aren't doing I/O, only
|
|
* setting up a mapping, so really we're using iomap_begin() as a way
|
|
* to look up our filesystem block.
|
|
*/
|
|
pos = (loff_t)pgoff << PAGE_SHIFT;
|
|
error = ops->iomap_begin(inode, pos, PMD_SIZE, iomap_flags, &iomap);
|
|
if (error)
|
|
goto fallback;
|
|
|
|
if (iomap.offset + iomap.length < pos + PMD_SIZE)
|
|
goto finish_iomap;
|
|
|
|
/*
|
|
* grab_mapping_entry() will make sure we get a 2M empty entry, a DAX
|
|
* PMD or a HZP entry. If it can't (because a 4k page is already in
|
|
* the tree, for instance), it will return -EEXIST and we just fall
|
|
* back to 4k entries.
|
|
*/
|
|
entry = grab_mapping_entry(mapping, pgoff, RADIX_DAX_PMD);
|
|
if (IS_ERR(entry))
|
|
goto finish_iomap;
|
|
|
|
vmf.pgoff = pgoff;
|
|
vmf.flags = flags;
|
|
vmf.gfp_mask = mapping_gfp_mask(mapping) | __GFP_IO;
|
|
|
|
switch (iomap.type) {
|
|
case IOMAP_MAPPED:
|
|
result = dax_pmd_insert_mapping(vma, pmd, &vmf, address,
|
|
&iomap, pos, write, &entry);
|
|
break;
|
|
case IOMAP_UNWRITTEN:
|
|
case IOMAP_HOLE:
|
|
if (WARN_ON_ONCE(write))
|
|
goto unlock_entry;
|
|
result = dax_pmd_load_hole(vma, pmd, &vmf, address, &iomap,
|
|
&entry);
|
|
break;
|
|
default:
|
|
WARN_ON_ONCE(1);
|
|
break;
|
|
}
|
|
|
|
unlock_entry:
|
|
put_locked_mapping_entry(mapping, pgoff, entry);
|
|
finish_iomap:
|
|
if (ops->iomap_end) {
|
|
int copied = PMD_SIZE;
|
|
|
|
if (result == VM_FAULT_FALLBACK)
|
|
copied = 0;
|
|
/*
|
|
* The fault is done by now and there's no way back (other
|
|
* thread may be already happily using PMD we have installed).
|
|
* Just ignore error from ->iomap_end since we cannot do much
|
|
* with it.
|
|
*/
|
|
ops->iomap_end(inode, pos, PMD_SIZE, copied, iomap_flags,
|
|
&iomap);
|
|
}
|
|
fallback:
|
|
if (result == VM_FAULT_FALLBACK) {
|
|
split_huge_pmd(vma, pmd, address);
|
|
count_vm_event(THP_FAULT_FALLBACK);
|
|
}
|
|
return result;
|
|
}
|
|
EXPORT_SYMBOL_GPL(dax_iomap_pmd_fault);
|
|
#endif /* CONFIG_FS_DAX_PMD */
|