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4f3b4f161d
Add a helper dax_ioamp_zero() to zero a range. This patch basically merges __dax_zero_page_range() and iomap_dax_zero(). Suggested-by: Christoph Hellwig <hch@infradead.org> Signed-off-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20200228163456.1587-7-vgoyal@redhat.com Signed-off-by: Dan Williams <dan.j.williams@intel.com>
1718 lines
46 KiB
C
1718 lines
46 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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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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#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/sched.h>
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#include <linux/sched/signal.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 <asm/pgalloc.h>
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#define CREATE_TRACE_POINTS
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#include <trace/events/fs_dax.h>
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static inline unsigned int pe_order(enum page_entry_size pe_size)
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{
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if (pe_size == PE_SIZE_PTE)
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return PAGE_SHIFT - PAGE_SHIFT;
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if (pe_size == PE_SIZE_PMD)
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return PMD_SHIFT - PAGE_SHIFT;
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if (pe_size == PE_SIZE_PUD)
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return PUD_SHIFT - PAGE_SHIFT;
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return ~0;
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}
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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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/* The 'colour' (ie low bits) within a PMD of a page offset. */
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#define PG_PMD_COLOUR ((PMD_SIZE >> PAGE_SHIFT) - 1)
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#define PG_PMD_NR (PMD_SIZE >> PAGE_SHIFT)
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/* The order of a PMD entry */
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#define PMD_ORDER (PMD_SHIFT - PAGE_SHIFT)
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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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/*
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* DAX pagecache entries use XArray value entries so they can't be mistaken
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* for pages. We use one bit for locking, one bit for the entry size (PMD)
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* and two more to tell us if the entry is a zero page or an empty entry that
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* is just used for locking. In total four special bits.
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*
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* If the PMD bit isn't set the entry has size PAGE_SIZE, and if the ZERO_PAGE
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* and EMPTY bits aren't set the entry is a normal DAX entry with a filesystem
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* block allocation.
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*/
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#define DAX_SHIFT (4)
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#define DAX_LOCKED (1UL << 0)
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#define DAX_PMD (1UL << 1)
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#define DAX_ZERO_PAGE (1UL << 2)
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#define DAX_EMPTY (1UL << 3)
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static unsigned long dax_to_pfn(void *entry)
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{
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return xa_to_value(entry) >> DAX_SHIFT;
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}
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static void *dax_make_entry(pfn_t pfn, unsigned long flags)
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{
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return xa_mk_value(flags | (pfn_t_to_pfn(pfn) << DAX_SHIFT));
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}
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static bool dax_is_locked(void *entry)
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{
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return xa_to_value(entry) & DAX_LOCKED;
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}
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static unsigned int dax_entry_order(void *entry)
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{
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if (xa_to_value(entry) & DAX_PMD)
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return PMD_ORDER;
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return 0;
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}
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static unsigned long dax_is_pmd_entry(void *entry)
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{
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return xa_to_value(entry) & DAX_PMD;
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}
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static bool dax_is_pte_entry(void *entry)
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{
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return !(xa_to_value(entry) & 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 xa_to_value(entry) & DAX_ZERO_PAGE;
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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 xa_to_value(entry) & DAX_EMPTY;
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}
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/*
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* true if the entry that was found is of a smaller order than the entry
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* we were looking for
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*/
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static bool dax_is_conflict(void *entry)
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{
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return entry == XA_RETRY_ENTRY;
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}
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/*
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* DAX page cache entry locking
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*/
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struct exceptional_entry_key {
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struct xarray *xa;
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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_entry_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 xa_state *xas,
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void *entry, struct exceptional_entry_key *key)
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{
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unsigned long hash;
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unsigned long index = xas->xa_index;
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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 &= ~PG_PMD_COLOUR;
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key->xa = xas->xa;
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key->entry_start = index;
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hash = hash_long((unsigned long)xas->xa ^ 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_entry_t *wait,
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unsigned int mode, 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->xa != ewait->key.xa ||
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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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* @entry may no longer be the entry at the index in the mapping.
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* The important information it's conveying is whether the entry at
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* this index used to be a PMD entry.
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*/
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static void dax_wake_entry(struct xa_state *xas, 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(xas, entry, &key);
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/*
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* Checking for locked entry and prepare_to_wait_exclusive() happens
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* under the i_pages lock, ditto for entry handling in our callers.
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* So at this point all tasks that could have seen our entry locked
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* must be in the waitqueue and the following check will see them.
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*/
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if (waitqueue_active(wq))
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__wake_up(wq, TASK_NORMAL, wake_all ? 0 : 1, &key);
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}
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/*
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* Look up entry in page cache, wait for it to become unlocked if it
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* is a DAX entry and return it. The caller must subsequently call
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* put_unlocked_entry() if it did not lock the entry or dax_unlock_entry()
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* if it did. The entry returned may have a larger order than @order.
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* If @order is larger than the order of the entry found in i_pages, this
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* function returns a dax_is_conflict entry.
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*
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* Must be called with the i_pages lock held.
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*/
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static void *get_unlocked_entry(struct xa_state *xas, unsigned int order)
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{
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void *entry;
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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 = xas_find_conflict(xas);
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if (!entry || WARN_ON_ONCE(!xa_is_value(entry)))
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return entry;
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if (dax_entry_order(entry) < order)
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return XA_RETRY_ENTRY;
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if (!dax_is_locked(entry))
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return entry;
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wq = dax_entry_waitqueue(xas, entry, &ewait.key);
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prepare_to_wait_exclusive(wq, &ewait.wait,
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TASK_UNINTERRUPTIBLE);
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xas_unlock_irq(xas);
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xas_reset(xas);
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schedule();
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finish_wait(wq, &ewait.wait);
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xas_lock_irq(xas);
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}
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}
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/*
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* The only thing keeping the address space around is the i_pages lock
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* (it's cycled in clear_inode() after removing the entries from i_pages)
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* After we call xas_unlock_irq(), we cannot touch xas->xa.
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*/
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static void wait_entry_unlocked(struct xa_state *xas, void *entry)
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{
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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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wq = dax_entry_waitqueue(xas, entry, &ewait.key);
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/*
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* Unlike get_unlocked_entry() there is no guarantee that this
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* path ever successfully retrieves an unlocked entry before an
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* inode dies. Perform a non-exclusive wait in case this path
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* never successfully performs its own wake up.
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*/
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prepare_to_wait(wq, &ewait.wait, TASK_UNINTERRUPTIBLE);
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xas_unlock_irq(xas);
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schedule();
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finish_wait(wq, &ewait.wait);
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}
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static void put_unlocked_entry(struct xa_state *xas, void *entry)
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{
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/* If we were the only waiter woken, wake the next one */
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if (entry && !dax_is_conflict(entry))
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dax_wake_entry(xas, entry, false);
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}
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/*
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* We used the xa_state to get the entry, but then we locked the entry and
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* dropped the xa_lock, so we know the xa_state is stale and must be reset
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* before use.
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*/
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static void dax_unlock_entry(struct xa_state *xas, void *entry)
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{
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void *old;
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BUG_ON(dax_is_locked(entry));
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xas_reset(xas);
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xas_lock_irq(xas);
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old = xas_store(xas, entry);
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xas_unlock_irq(xas);
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BUG_ON(!dax_is_locked(old));
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dax_wake_entry(xas, entry, false);
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}
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/*
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* Return: The entry stored at this location before it was locked.
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*/
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static void *dax_lock_entry(struct xa_state *xas, void *entry)
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{
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unsigned long v = xa_to_value(entry);
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return xas_store(xas, xa_mk_value(v | DAX_LOCKED));
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}
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static unsigned long dax_entry_size(void *entry)
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{
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if (dax_is_zero_entry(entry))
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return 0;
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else if (dax_is_empty_entry(entry))
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return 0;
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else if (dax_is_pmd_entry(entry))
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return PMD_SIZE;
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else
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return PAGE_SIZE;
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}
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static unsigned long dax_end_pfn(void *entry)
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{
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return dax_to_pfn(entry) + dax_entry_size(entry) / PAGE_SIZE;
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}
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/*
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* Iterate through all mapped pfns represented by an entry, i.e. skip
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* 'empty' and 'zero' entries.
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*/
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#define for_each_mapped_pfn(entry, pfn) \
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for (pfn = dax_to_pfn(entry); \
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pfn < dax_end_pfn(entry); pfn++)
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/*
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* TODO: for reflink+dax we need a way to associate a single page with
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* multiple address_space instances at different linear_page_index()
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* offsets.
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*/
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static void dax_associate_entry(void *entry, struct address_space *mapping,
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struct vm_area_struct *vma, unsigned long address)
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{
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unsigned long size = dax_entry_size(entry), pfn, index;
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int i = 0;
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if (IS_ENABLED(CONFIG_FS_DAX_LIMITED))
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return;
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index = linear_page_index(vma, address & ~(size - 1));
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for_each_mapped_pfn(entry, pfn) {
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struct page *page = pfn_to_page(pfn);
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WARN_ON_ONCE(page->mapping);
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page->mapping = mapping;
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page->index = index + i++;
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}
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}
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static void dax_disassociate_entry(void *entry, struct address_space *mapping,
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bool trunc)
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{
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unsigned long pfn;
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if (IS_ENABLED(CONFIG_FS_DAX_LIMITED))
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return;
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for_each_mapped_pfn(entry, pfn) {
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struct page *page = pfn_to_page(pfn);
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WARN_ON_ONCE(trunc && page_ref_count(page) > 1);
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WARN_ON_ONCE(page->mapping && page->mapping != mapping);
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page->mapping = NULL;
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page->index = 0;
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}
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}
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static struct page *dax_busy_page(void *entry)
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{
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unsigned long pfn;
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for_each_mapped_pfn(entry, pfn) {
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struct page *page = pfn_to_page(pfn);
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if (page_ref_count(page) > 1)
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return page;
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}
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return NULL;
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}
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/*
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* dax_lock_mapping_entry - Lock the DAX entry corresponding to a page
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* @page: The page whose entry we want to lock
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*
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* Context: Process context.
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* Return: A cookie to pass to dax_unlock_page() or 0 if the entry could
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* not be locked.
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*/
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dax_entry_t dax_lock_page(struct page *page)
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{
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XA_STATE(xas, NULL, 0);
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void *entry;
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/* Ensure page->mapping isn't freed while we look at it */
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rcu_read_lock();
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for (;;) {
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struct address_space *mapping = READ_ONCE(page->mapping);
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entry = NULL;
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if (!mapping || !dax_mapping(mapping))
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break;
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/*
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* In the device-dax case there's no need to lock, a
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* struct dev_pagemap pin is sufficient to keep the
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* inode alive, and we assume we have dev_pagemap pin
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* otherwise we would not have a valid pfn_to_page()
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* translation.
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*/
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entry = (void *)~0UL;
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if (S_ISCHR(mapping->host->i_mode))
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break;
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xas.xa = &mapping->i_pages;
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xas_lock_irq(&xas);
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if (mapping != page->mapping) {
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xas_unlock_irq(&xas);
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continue;
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}
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xas_set(&xas, page->index);
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entry = xas_load(&xas);
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if (dax_is_locked(entry)) {
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rcu_read_unlock();
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wait_entry_unlocked(&xas, entry);
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rcu_read_lock();
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continue;
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}
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dax_lock_entry(&xas, entry);
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xas_unlock_irq(&xas);
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break;
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}
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rcu_read_unlock();
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return (dax_entry_t)entry;
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}
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void dax_unlock_page(struct page *page, dax_entry_t cookie)
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{
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struct address_space *mapping = page->mapping;
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XA_STATE(xas, &mapping->i_pages, page->index);
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if (S_ISCHR(mapping->host->i_mode))
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return;
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dax_unlock_entry(&xas, (void *)cookie);
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}
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/*
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* Find page cache entry at given index. If it is a DAX entry, return it
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* with the entry locked. If the page cache doesn't contain an entry at
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* that index, add a locked empty entry.
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*
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* When requesting an entry with size DAX_PMD, grab_mapping_entry() will
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* either return that locked entry or will return VM_FAULT_FALLBACK.
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* This will happen if there are any PTE entries within the PMD range
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* that we are requesting.
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*
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* We always favor PTE entries over PMD entries. There isn't a flow where we
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* evict PTE entries in order to 'upgrade' them to a PMD entry. A PMD
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* insertion will fail if it finds any PTE entries already in the tree, and a
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* PTE insertion will cause an existing PMD entry to be unmapped and
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* downgraded to PTE entries. This happens for both PMD zero pages as
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* well as PMD empty entries.
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*
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* The exception to this downgrade path is for PMD entries that have
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* real storage backing them. We will leave these real PMD entries in
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* the tree, and PTE writes will simply dirty the entire PMD 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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* On error, this function does not return an ERR_PTR. Instead it returns
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* a VM_FAULT code, encoded as an xarray internal entry. The ERR_PTR values
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* overlap with xarray value entries.
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*/
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static void *grab_mapping_entry(struct xa_state *xas,
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struct address_space *mapping, unsigned int order)
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{
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unsigned long index = xas->xa_index;
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bool pmd_downgrade = false; /* splitting PMD entry into PTE entries? */
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void *entry;
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retry:
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xas_lock_irq(xas);
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entry = get_unlocked_entry(xas, order);
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|
|
if (entry) {
|
|
if (dax_is_conflict(entry))
|
|
goto fallback;
|
|
if (!xa_is_value(entry)) {
|
|
xas_set_err(xas, EIO);
|
|
goto out_unlock;
|
|
}
|
|
|
|
if (order == 0) {
|
|
if (dax_is_pmd_entry(entry) &&
|
|
(dax_is_zero_entry(entry) ||
|
|
dax_is_empty_entry(entry))) {
|
|
pmd_downgrade = true;
|
|
}
|
|
}
|
|
}
|
|
|
|
if (pmd_downgrade) {
|
|
/*
|
|
* Make sure 'entry' remains valid while we drop
|
|
* the i_pages lock.
|
|
*/
|
|
dax_lock_entry(xas, entry);
|
|
|
|
/*
|
|
* Besides huge zero pages the only other thing that gets
|
|
* downgraded are empty entries which don't need to be
|
|
* unmapped.
|
|
*/
|
|
if (dax_is_zero_entry(entry)) {
|
|
xas_unlock_irq(xas);
|
|
unmap_mapping_pages(mapping,
|
|
xas->xa_index & ~PG_PMD_COLOUR,
|
|
PG_PMD_NR, false);
|
|
xas_reset(xas);
|
|
xas_lock_irq(xas);
|
|
}
|
|
|
|
dax_disassociate_entry(entry, mapping, false);
|
|
xas_store(xas, NULL); /* undo the PMD join */
|
|
dax_wake_entry(xas, entry, true);
|
|
mapping->nrexceptional--;
|
|
entry = NULL;
|
|
xas_set(xas, index);
|
|
}
|
|
|
|
if (entry) {
|
|
dax_lock_entry(xas, entry);
|
|
} else {
|
|
unsigned long flags = DAX_EMPTY;
|
|
|
|
if (order > 0)
|
|
flags |= DAX_PMD;
|
|
entry = dax_make_entry(pfn_to_pfn_t(0), flags);
|
|
dax_lock_entry(xas, entry);
|
|
if (xas_error(xas))
|
|
goto out_unlock;
|
|
mapping->nrexceptional++;
|
|
}
|
|
|
|
out_unlock:
|
|
xas_unlock_irq(xas);
|
|
if (xas_nomem(xas, mapping_gfp_mask(mapping) & ~__GFP_HIGHMEM))
|
|
goto retry;
|
|
if (xas->xa_node == XA_ERROR(-ENOMEM))
|
|
return xa_mk_internal(VM_FAULT_OOM);
|
|
if (xas_error(xas))
|
|
return xa_mk_internal(VM_FAULT_SIGBUS);
|
|
return entry;
|
|
fallback:
|
|
xas_unlock_irq(xas);
|
|
return xa_mk_internal(VM_FAULT_FALLBACK);
|
|
}
|
|
|
|
/**
|
|
* dax_layout_busy_page - find first pinned page in @mapping
|
|
* @mapping: address space to scan for a page with ref count > 1
|
|
*
|
|
* DAX requires ZONE_DEVICE mapped pages. These pages are never
|
|
* 'onlined' to the page allocator so they are considered idle when
|
|
* page->count == 1. A filesystem uses this interface to determine if
|
|
* any page in the mapping is busy, i.e. for DMA, or other
|
|
* get_user_pages() usages.
|
|
*
|
|
* It is expected that the filesystem is holding locks to block the
|
|
* establishment of new mappings in this address_space. I.e. it expects
|
|
* to be able to run unmap_mapping_range() and subsequently not race
|
|
* mapping_mapped() becoming true.
|
|
*/
|
|
struct page *dax_layout_busy_page(struct address_space *mapping)
|
|
{
|
|
XA_STATE(xas, &mapping->i_pages, 0);
|
|
void *entry;
|
|
unsigned int scanned = 0;
|
|
struct page *page = NULL;
|
|
|
|
/*
|
|
* In the 'limited' case get_user_pages() for dax is disabled.
|
|
*/
|
|
if (IS_ENABLED(CONFIG_FS_DAX_LIMITED))
|
|
return NULL;
|
|
|
|
if (!dax_mapping(mapping) || !mapping_mapped(mapping))
|
|
return NULL;
|
|
|
|
/*
|
|
* If we race get_user_pages_fast() here either we'll see the
|
|
* elevated page count in the iteration and wait, or
|
|
* get_user_pages_fast() will see that the page it took a reference
|
|
* against is no longer mapped in the page tables and bail to the
|
|
* get_user_pages() slow path. The slow path is protected by
|
|
* pte_lock() and pmd_lock(). New references are not taken without
|
|
* holding those locks, and unmap_mapping_range() will not zero the
|
|
* pte or pmd without holding the respective lock, so we are
|
|
* guaranteed to either see new references or prevent new
|
|
* references from being established.
|
|
*/
|
|
unmap_mapping_range(mapping, 0, 0, 0);
|
|
|
|
xas_lock_irq(&xas);
|
|
xas_for_each(&xas, entry, ULONG_MAX) {
|
|
if (WARN_ON_ONCE(!xa_is_value(entry)))
|
|
continue;
|
|
if (unlikely(dax_is_locked(entry)))
|
|
entry = get_unlocked_entry(&xas, 0);
|
|
if (entry)
|
|
page = dax_busy_page(entry);
|
|
put_unlocked_entry(&xas, entry);
|
|
if (page)
|
|
break;
|
|
if (++scanned % XA_CHECK_SCHED)
|
|
continue;
|
|
|
|
xas_pause(&xas);
|
|
xas_unlock_irq(&xas);
|
|
cond_resched();
|
|
xas_lock_irq(&xas);
|
|
}
|
|
xas_unlock_irq(&xas);
|
|
return page;
|
|
}
|
|
EXPORT_SYMBOL_GPL(dax_layout_busy_page);
|
|
|
|
static int __dax_invalidate_entry(struct address_space *mapping,
|
|
pgoff_t index, bool trunc)
|
|
{
|
|
XA_STATE(xas, &mapping->i_pages, index);
|
|
int ret = 0;
|
|
void *entry;
|
|
|
|
xas_lock_irq(&xas);
|
|
entry = get_unlocked_entry(&xas, 0);
|
|
if (!entry || WARN_ON_ONCE(!xa_is_value(entry)))
|
|
goto out;
|
|
if (!trunc &&
|
|
(xas_get_mark(&xas, PAGECACHE_TAG_DIRTY) ||
|
|
xas_get_mark(&xas, PAGECACHE_TAG_TOWRITE)))
|
|
goto out;
|
|
dax_disassociate_entry(entry, mapping, trunc);
|
|
xas_store(&xas, NULL);
|
|
mapping->nrexceptional--;
|
|
ret = 1;
|
|
out:
|
|
put_unlocked_entry(&xas, entry);
|
|
xas_unlock_irq(&xas);
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Delete DAX entry at @index from @mapping. Wait for it
|
|
* to be unlocked before deleting it.
|
|
*/
|
|
int dax_delete_mapping_entry(struct address_space *mapping, pgoff_t index)
|
|
{
|
|
int ret = __dax_invalidate_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
|
|
* page cache (usually fs-private i_mmap_sem for writing). Since the
|
|
* caller has seen a DAX entry for this index, we better find it
|
|
* at that index as well...
|
|
*/
|
|
WARN_ON_ONCE(!ret);
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Invalidate DAX entry if it is clean.
|
|
*/
|
|
int dax_invalidate_mapping_entry_sync(struct address_space *mapping,
|
|
pgoff_t index)
|
|
{
|
|
return __dax_invalidate_entry(mapping, index, false);
|
|
}
|
|
|
|
static int copy_user_dax(struct block_device *bdev, struct dax_device *dax_dev,
|
|
sector_t sector, size_t size, struct page *to,
|
|
unsigned long vaddr)
|
|
{
|
|
void *vto, *kaddr;
|
|
pgoff_t pgoff;
|
|
long rc;
|
|
int id;
|
|
|
|
rc = bdev_dax_pgoff(bdev, sector, size, &pgoff);
|
|
if (rc)
|
|
return rc;
|
|
|
|
id = dax_read_lock();
|
|
rc = dax_direct_access(dax_dev, pgoff, PHYS_PFN(size), &kaddr, NULL);
|
|
if (rc < 0) {
|
|
dax_read_unlock(id);
|
|
return rc;
|
|
}
|
|
vto = kmap_atomic(to);
|
|
copy_user_page(vto, (void __force *)kaddr, vaddr, to);
|
|
kunmap_atomic(vto);
|
|
dax_read_unlock(id);
|
|
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_entry(struct xa_state *xas,
|
|
struct address_space *mapping, struct vm_fault *vmf,
|
|
void *entry, pfn_t pfn, unsigned long flags, bool dirty)
|
|
{
|
|
void *new_entry = dax_make_entry(pfn, flags);
|
|
|
|
if (dirty)
|
|
__mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
|
|
|
|
if (dax_is_zero_entry(entry) && !(flags & DAX_ZERO_PAGE)) {
|
|
unsigned long index = xas->xa_index;
|
|
/* we are replacing a zero page with block mapping */
|
|
if (dax_is_pmd_entry(entry))
|
|
unmap_mapping_pages(mapping, index & ~PG_PMD_COLOUR,
|
|
PG_PMD_NR, false);
|
|
else /* pte entry */
|
|
unmap_mapping_pages(mapping, index, 1, false);
|
|
}
|
|
|
|
xas_reset(xas);
|
|
xas_lock_irq(xas);
|
|
if (dax_is_zero_entry(entry) || dax_is_empty_entry(entry)) {
|
|
void *old;
|
|
|
|
dax_disassociate_entry(entry, mapping, false);
|
|
dax_associate_entry(new_entry, mapping, vmf->vma, vmf->address);
|
|
/*
|
|
* Only swap our new entry into the page cache if the current
|
|
* entry is a zero page or an empty entry. If a normal PTE or
|
|
* PMD entry is already in the cache, 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.
|
|
*/
|
|
old = dax_lock_entry(xas, new_entry);
|
|
WARN_ON_ONCE(old != xa_mk_value(xa_to_value(entry) |
|
|
DAX_LOCKED));
|
|
entry = new_entry;
|
|
} else {
|
|
xas_load(xas); /* Walk the xa_state */
|
|
}
|
|
|
|
if (dirty)
|
|
xas_set_mark(xas, PAGECACHE_TAG_DIRTY);
|
|
|
|
xas_unlock_irq(xas);
|
|
return 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_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;
|
|
|
|
i_mmap_lock_read(mapping);
|
|
vma_interval_tree_foreach(vma, &mapping->i_mmap, index, index) {
|
|
struct mmu_notifier_range range;
|
|
unsigned long address;
|
|
|
|
cond_resched();
|
|
|
|
if (!(vma->vm_flags & VM_SHARED))
|
|
continue;
|
|
|
|
address = pgoff_address(index, vma);
|
|
|
|
/*
|
|
* Note because we provide range to follow_pte_pmd it will
|
|
* call mmu_notifier_invalidate_range_start() on our behalf
|
|
* before taking any lock.
|
|
*/
|
|
if (follow_pte_pmd(vma->vm_mm, address, &range,
|
|
&ptep, &pmdp, &ptl))
|
|
continue;
|
|
|
|
/*
|
|
* No need to call mmu_notifier_invalidate_range() as we are
|
|
* downgrading page table protection not changing it to point
|
|
* to a new page.
|
|
*
|
|
* See Documentation/vm/mmu_notifier.rst
|
|
*/
|
|
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_invalidate(vma, address, pmdp);
|
|
pmd = pmd_wrprotect(pmd);
|
|
pmd = pmd_mkclean(pmd);
|
|
set_pmd_at(vma->vm_mm, address, pmdp, pmd);
|
|
unlock_pmd:
|
|
#endif
|
|
spin_unlock(ptl);
|
|
} 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);
|
|
unlock_pte:
|
|
pte_unmap_unlock(ptep, ptl);
|
|
}
|
|
|
|
mmu_notifier_invalidate_range_end(&range);
|
|
}
|
|
i_mmap_unlock_read(mapping);
|
|
}
|
|
|
|
static int dax_writeback_one(struct xa_state *xas, struct dax_device *dax_dev,
|
|
struct address_space *mapping, void *entry)
|
|
{
|
|
unsigned long pfn, index, count;
|
|
long ret = 0;
|
|
|
|
/*
|
|
* A page got tagged dirty in DAX mapping? Something is seriously
|
|
* wrong.
|
|
*/
|
|
if (WARN_ON(!xa_is_value(entry)))
|
|
return -EIO;
|
|
|
|
if (unlikely(dax_is_locked(entry))) {
|
|
void *old_entry = entry;
|
|
|
|
entry = get_unlocked_entry(xas, 0);
|
|
|
|
/* Entry got punched out / reallocated? */
|
|
if (!entry || WARN_ON_ONCE(!xa_is_value(entry)))
|
|
goto put_unlocked;
|
|
/*
|
|
* Entry got reallocated elsewhere? No need to writeback.
|
|
* We have to compare pfns as we must not bail out due to
|
|
* difference in lockbit or entry type.
|
|
*/
|
|
if (dax_to_pfn(old_entry) != dax_to_pfn(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 done this entry */
|
|
if (!xas_get_mark(xas, PAGECACHE_TAG_TOWRITE))
|
|
goto put_unlocked;
|
|
}
|
|
|
|
/* Lock the entry to serialize with page faults */
|
|
dax_lock_entry(xas, entry);
|
|
|
|
/*
|
|
* 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 the i_pages lock and once they do that
|
|
* they will see the entry locked and wait for it to unlock.
|
|
*/
|
|
xas_clear_mark(xas, PAGECACHE_TAG_TOWRITE);
|
|
xas_unlock_irq(xas);
|
|
|
|
/*
|
|
* If dax_writeback_mapping_range() was given a wbc->range_start
|
|
* in the middle of a PMD, the 'index' we use needs to be
|
|
* aligned to the start of the PMD.
|
|
* This allows us to flush for PMD_SIZE and not have to worry about
|
|
* partial PMD writebacks.
|
|
*/
|
|
pfn = dax_to_pfn(entry);
|
|
count = 1UL << dax_entry_order(entry);
|
|
index = xas->xa_index & ~(count - 1);
|
|
|
|
dax_entry_mkclean(mapping, index, pfn);
|
|
dax_flush(dax_dev, page_address(pfn_to_page(pfn)), count * PAGE_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.
|
|
*/
|
|
xas_reset(xas);
|
|
xas_lock_irq(xas);
|
|
xas_store(xas, entry);
|
|
xas_clear_mark(xas, PAGECACHE_TAG_DIRTY);
|
|
dax_wake_entry(xas, entry, false);
|
|
|
|
trace_dax_writeback_one(mapping->host, index, count);
|
|
return ret;
|
|
|
|
put_unlocked:
|
|
put_unlocked_entry(xas, entry);
|
|
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 dax_device *dax_dev, struct writeback_control *wbc)
|
|
{
|
|
XA_STATE(xas, &mapping->i_pages, wbc->range_start >> PAGE_SHIFT);
|
|
struct inode *inode = mapping->host;
|
|
pgoff_t end_index = wbc->range_end >> PAGE_SHIFT;
|
|
void *entry;
|
|
int ret = 0;
|
|
unsigned int scanned = 0;
|
|
|
|
if (WARN_ON_ONCE(inode->i_blkbits != PAGE_SHIFT))
|
|
return -EIO;
|
|
|
|
if (!mapping->nrexceptional || wbc->sync_mode != WB_SYNC_ALL)
|
|
return 0;
|
|
|
|
trace_dax_writeback_range(inode, xas.xa_index, end_index);
|
|
|
|
tag_pages_for_writeback(mapping, xas.xa_index, end_index);
|
|
|
|
xas_lock_irq(&xas);
|
|
xas_for_each_marked(&xas, entry, end_index, PAGECACHE_TAG_TOWRITE) {
|
|
ret = dax_writeback_one(&xas, dax_dev, mapping, entry);
|
|
if (ret < 0) {
|
|
mapping_set_error(mapping, ret);
|
|
break;
|
|
}
|
|
if (++scanned % XA_CHECK_SCHED)
|
|
continue;
|
|
|
|
xas_pause(&xas);
|
|
xas_unlock_irq(&xas);
|
|
cond_resched();
|
|
xas_lock_irq(&xas);
|
|
}
|
|
xas_unlock_irq(&xas);
|
|
trace_dax_writeback_range_done(inode, xas.xa_index, end_index);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(dax_writeback_mapping_range);
|
|
|
|
static sector_t dax_iomap_sector(struct iomap *iomap, loff_t pos)
|
|
{
|
|
return (iomap->addr + (pos & PAGE_MASK) - iomap->offset) >> 9;
|
|
}
|
|
|
|
static int dax_iomap_pfn(struct iomap *iomap, loff_t pos, size_t size,
|
|
pfn_t *pfnp)
|
|
{
|
|
const sector_t sector = dax_iomap_sector(iomap, pos);
|
|
pgoff_t pgoff;
|
|
int id, rc;
|
|
long length;
|
|
|
|
rc = bdev_dax_pgoff(iomap->bdev, sector, size, &pgoff);
|
|
if (rc)
|
|
return rc;
|
|
id = dax_read_lock();
|
|
length = dax_direct_access(iomap->dax_dev, pgoff, PHYS_PFN(size),
|
|
NULL, pfnp);
|
|
if (length < 0) {
|
|
rc = length;
|
|
goto out;
|
|
}
|
|
rc = -EINVAL;
|
|
if (PFN_PHYS(length) < size)
|
|
goto out;
|
|
if (pfn_t_to_pfn(*pfnp) & (PHYS_PFN(size)-1))
|
|
goto out;
|
|
/* For larger pages we need devmap */
|
|
if (length > 1 && !pfn_t_devmap(*pfnp))
|
|
goto out;
|
|
rc = 0;
|
|
out:
|
|
dax_read_unlock(id);
|
|
return rc;
|
|
}
|
|
|
|
/*
|
|
* 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. Instead we insert a read-only mapping of the 4k zero page.
|
|
* If this page is ever written to we will re-fault and change the mapping to
|
|
* point to real DAX storage instead.
|
|
*/
|
|
static vm_fault_t dax_load_hole(struct xa_state *xas,
|
|
struct address_space *mapping, void **entry,
|
|
struct vm_fault *vmf)
|
|
{
|
|
struct inode *inode = mapping->host;
|
|
unsigned long vaddr = vmf->address;
|
|
pfn_t pfn = pfn_to_pfn_t(my_zero_pfn(vaddr));
|
|
vm_fault_t ret;
|
|
|
|
*entry = dax_insert_entry(xas, mapping, vmf, *entry, pfn,
|
|
DAX_ZERO_PAGE, false);
|
|
|
|
ret = vmf_insert_mixed(vmf->vma, vaddr, pfn);
|
|
trace_dax_load_hole(inode, vmf, ret);
|
|
return ret;
|
|
}
|
|
|
|
int dax_iomap_zero(loff_t pos, unsigned offset, unsigned size,
|
|
struct iomap *iomap)
|
|
{
|
|
sector_t sector = iomap_sector(iomap, pos & PAGE_MASK);
|
|
pgoff_t pgoff;
|
|
long rc, id;
|
|
void *kaddr;
|
|
bool page_aligned = false;
|
|
|
|
|
|
if (IS_ALIGNED(sector << SECTOR_SHIFT, PAGE_SIZE) &&
|
|
IS_ALIGNED(size, PAGE_SIZE))
|
|
page_aligned = true;
|
|
|
|
rc = bdev_dax_pgoff(iomap->bdev, sector, PAGE_SIZE, &pgoff);
|
|
if (rc)
|
|
return rc;
|
|
|
|
id = dax_read_lock();
|
|
|
|
if (page_aligned)
|
|
rc = dax_zero_page_range(iomap->dax_dev, pgoff,
|
|
size >> PAGE_SHIFT);
|
|
else
|
|
rc = dax_direct_access(iomap->dax_dev, pgoff, 1, &kaddr, NULL);
|
|
if (rc < 0) {
|
|
dax_read_unlock(id);
|
|
return rc;
|
|
}
|
|
|
|
if (!page_aligned) {
|
|
memset(kaddr + offset, 0, size);
|
|
dax_flush(iomap->dax_dev, kaddr + offset, size);
|
|
}
|
|
dax_read_unlock(id);
|
|
return 0;
|
|
}
|
|
|
|
static loff_t
|
|
dax_iomap_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
|
|
struct iomap *iomap, struct iomap *srcmap)
|
|
{
|
|
struct block_device *bdev = iomap->bdev;
|
|
struct dax_device *dax_dev = iomap->dax_dev;
|
|
struct iov_iter *iter = data;
|
|
loff_t end = pos + length, done = 0;
|
|
ssize_t ret = 0;
|
|
size_t xfer;
|
|
int id;
|
|
|
|
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) {
|
|
invalidate_inode_pages2_range(inode->i_mapping,
|
|
pos >> PAGE_SHIFT,
|
|
(end - 1) >> PAGE_SHIFT);
|
|
}
|
|
|
|
id = dax_read_lock();
|
|
while (pos < end) {
|
|
unsigned offset = pos & (PAGE_SIZE - 1);
|
|
const size_t size = ALIGN(length + offset, PAGE_SIZE);
|
|
const sector_t sector = dax_iomap_sector(iomap, pos);
|
|
ssize_t map_len;
|
|
pgoff_t pgoff;
|
|
void *kaddr;
|
|
|
|
if (fatal_signal_pending(current)) {
|
|
ret = -EINTR;
|
|
break;
|
|
}
|
|
|
|
ret = bdev_dax_pgoff(bdev, sector, size, &pgoff);
|
|
if (ret)
|
|
break;
|
|
|
|
map_len = dax_direct_access(dax_dev, pgoff, PHYS_PFN(size),
|
|
&kaddr, NULL);
|
|
if (map_len < 0) {
|
|
ret = map_len;
|
|
break;
|
|
}
|
|
|
|
map_len = PFN_PHYS(map_len);
|
|
kaddr += offset;
|
|
map_len -= offset;
|
|
if (map_len > end - pos)
|
|
map_len = end - pos;
|
|
|
|
/*
|
|
* The userspace address for the memory copy has already been
|
|
* validated via access_ok() in either vfs_read() or
|
|
* vfs_write(), depending on which operation we are doing.
|
|
*/
|
|
if (iov_iter_rw(iter) == WRITE)
|
|
xfer = dax_copy_from_iter(dax_dev, pgoff, kaddr,
|
|
map_len, iter);
|
|
else
|
|
xfer = dax_copy_to_iter(dax_dev, pgoff, kaddr,
|
|
map_len, iter);
|
|
|
|
pos += xfer;
|
|
length -= xfer;
|
|
done += xfer;
|
|
|
|
if (xfer == 0)
|
|
ret = -EFAULT;
|
|
if (xfer < map_len)
|
|
break;
|
|
}
|
|
dax_read_unlock(id);
|
|
|
|
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,
|
|
const 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) {
|
|
lockdep_assert_held_write(&inode->i_rwsem);
|
|
flags |= IOMAP_WRITE;
|
|
} else {
|
|
lockdep_assert_held(&inode->i_rwsem);
|
|
}
|
|
|
|
if (iocb->ki_flags & IOCB_NOWAIT)
|
|
flags |= IOMAP_NOWAIT;
|
|
|
|
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 vm_fault_t dax_fault_return(int error)
|
|
{
|
|
if (error == 0)
|
|
return VM_FAULT_NOPAGE;
|
|
return vmf_error(error);
|
|
}
|
|
|
|
/*
|
|
* MAP_SYNC on a dax mapping guarantees dirty metadata is
|
|
* flushed on write-faults (non-cow), but not read-faults.
|
|
*/
|
|
static bool dax_fault_is_synchronous(unsigned long flags,
|
|
struct vm_area_struct *vma, struct iomap *iomap)
|
|
{
|
|
return (flags & IOMAP_WRITE) && (vma->vm_flags & VM_SYNC)
|
|
&& (iomap->flags & IOMAP_F_DIRTY);
|
|
}
|
|
|
|
static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp,
|
|
int *iomap_errp, const struct iomap_ops *ops)
|
|
{
|
|
struct vm_area_struct *vma = vmf->vma;
|
|
struct address_space *mapping = vma->vm_file->f_mapping;
|
|
XA_STATE(xas, &mapping->i_pages, vmf->pgoff);
|
|
struct inode *inode = mapping->host;
|
|
unsigned long vaddr = vmf->address;
|
|
loff_t pos = (loff_t)vmf->pgoff << PAGE_SHIFT;
|
|
struct iomap iomap = { .type = IOMAP_HOLE };
|
|
struct iomap srcmap = { .type = IOMAP_HOLE };
|
|
unsigned flags = IOMAP_FAULT;
|
|
int error, major = 0;
|
|
bool write = vmf->flags & FAULT_FLAG_WRITE;
|
|
bool sync;
|
|
vm_fault_t ret = 0;
|
|
void *entry;
|
|
pfn_t pfn;
|
|
|
|
trace_dax_pte_fault(inode, vmf, ret);
|
|
/*
|
|
* 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)) {
|
|
ret = VM_FAULT_SIGBUS;
|
|
goto out;
|
|
}
|
|
|
|
if (write && !vmf->cow_page)
|
|
flags |= IOMAP_WRITE;
|
|
|
|
entry = grab_mapping_entry(&xas, mapping, 0);
|
|
if (xa_is_internal(entry)) {
|
|
ret = xa_to_internal(entry);
|
|
goto out;
|
|
}
|
|
|
|
/*
|
|
* It is possible, particularly with mixed reads & writes to private
|
|
* mappings, that we have raced with a PMD fault that overlaps with
|
|
* the PTE we need to set up. If so just return and the fault will be
|
|
* retried.
|
|
*/
|
|
if (pmd_trans_huge(*vmf->pmd) || pmd_devmap(*vmf->pmd)) {
|
|
ret = VM_FAULT_NOPAGE;
|
|
goto unlock_entry;
|
|
}
|
|
|
|
/*
|
|
* 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, &srcmap);
|
|
if (iomap_errp)
|
|
*iomap_errp = error;
|
|
if (error) {
|
|
ret = dax_fault_return(error);
|
|
goto unlock_entry;
|
|
}
|
|
if (WARN_ON_ONCE(iomap.offset + iomap.length < pos + PAGE_SIZE)) {
|
|
error = -EIO; /* fs corruption? */
|
|
goto error_finish_iomap;
|
|
}
|
|
|
|
if (vmf->cow_page) {
|
|
sector_t sector = dax_iomap_sector(&iomap, pos);
|
|
|
|
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, iomap.dax_dev,
|
|
sector, PAGE_SIZE, vmf->cow_page, vaddr);
|
|
break;
|
|
default:
|
|
WARN_ON_ONCE(1);
|
|
error = -EIO;
|
|
break;
|
|
}
|
|
|
|
if (error)
|
|
goto error_finish_iomap;
|
|
|
|
__SetPageUptodate(vmf->cow_page);
|
|
ret = finish_fault(vmf);
|
|
if (!ret)
|
|
ret = VM_FAULT_DONE_COW;
|
|
goto finish_iomap;
|
|
}
|
|
|
|
sync = dax_fault_is_synchronous(flags, vma, &iomap);
|
|
|
|
switch (iomap.type) {
|
|
case IOMAP_MAPPED:
|
|
if (iomap.flags & IOMAP_F_NEW) {
|
|
count_vm_event(PGMAJFAULT);
|
|
count_memcg_event_mm(vma->vm_mm, PGMAJFAULT);
|
|
major = VM_FAULT_MAJOR;
|
|
}
|
|
error = dax_iomap_pfn(&iomap, pos, PAGE_SIZE, &pfn);
|
|
if (error < 0)
|
|
goto error_finish_iomap;
|
|
|
|
entry = dax_insert_entry(&xas, mapping, vmf, entry, pfn,
|
|
0, write && !sync);
|
|
|
|
/*
|
|
* If we are doing synchronous page fault and inode needs fsync,
|
|
* we can insert PTE into page tables only after that happens.
|
|
* Skip insertion for now and return the pfn so that caller can
|
|
* insert it after fsync is done.
|
|
*/
|
|
if (sync) {
|
|
if (WARN_ON_ONCE(!pfnp)) {
|
|
error = -EIO;
|
|
goto error_finish_iomap;
|
|
}
|
|
*pfnp = pfn;
|
|
ret = VM_FAULT_NEEDDSYNC | major;
|
|
goto finish_iomap;
|
|
}
|
|
trace_dax_insert_mapping(inode, vmf, entry);
|
|
if (write)
|
|
ret = vmf_insert_mixed_mkwrite(vma, vaddr, pfn);
|
|
else
|
|
ret = vmf_insert_mixed(vma, vaddr, pfn);
|
|
|
|
goto finish_iomap;
|
|
case IOMAP_UNWRITTEN:
|
|
case IOMAP_HOLE:
|
|
if (!write) {
|
|
ret = dax_load_hole(&xas, mapping, &entry, vmf);
|
|
goto finish_iomap;
|
|
}
|
|
/*FALLTHRU*/
|
|
default:
|
|
WARN_ON_ONCE(1);
|
|
error = -EIO;
|
|
break;
|
|
}
|
|
|
|
error_finish_iomap:
|
|
ret = dax_fault_return(error);
|
|
finish_iomap:
|
|
if (ops->iomap_end) {
|
|
int copied = PAGE_SIZE;
|
|
|
|
if (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);
|
|
}
|
|
unlock_entry:
|
|
dax_unlock_entry(&xas, entry);
|
|
out:
|
|
trace_dax_pte_fault_done(inode, vmf, ret);
|
|
return ret | major;
|
|
}
|
|
|
|
#ifdef CONFIG_FS_DAX_PMD
|
|
static vm_fault_t dax_pmd_load_hole(struct xa_state *xas, struct vm_fault *vmf,
|
|
struct iomap *iomap, void **entry)
|
|
{
|
|
struct address_space *mapping = vmf->vma->vm_file->f_mapping;
|
|
unsigned long pmd_addr = vmf->address & PMD_MASK;
|
|
struct vm_area_struct *vma = vmf->vma;
|
|
struct inode *inode = mapping->host;
|
|
pgtable_t pgtable = NULL;
|
|
struct page *zero_page;
|
|
spinlock_t *ptl;
|
|
pmd_t pmd_entry;
|
|
pfn_t pfn;
|
|
|
|
zero_page = mm_get_huge_zero_page(vmf->vma->vm_mm);
|
|
|
|
if (unlikely(!zero_page))
|
|
goto fallback;
|
|
|
|
pfn = page_to_pfn_t(zero_page);
|
|
*entry = dax_insert_entry(xas, mapping, vmf, *entry, pfn,
|
|
DAX_PMD | DAX_ZERO_PAGE, false);
|
|
|
|
if (arch_needs_pgtable_deposit()) {
|
|
pgtable = pte_alloc_one(vma->vm_mm);
|
|
if (!pgtable)
|
|
return VM_FAULT_OOM;
|
|
}
|
|
|
|
ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd);
|
|
if (!pmd_none(*(vmf->pmd))) {
|
|
spin_unlock(ptl);
|
|
goto fallback;
|
|
}
|
|
|
|
if (pgtable) {
|
|
pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable);
|
|
mm_inc_nr_ptes(vma->vm_mm);
|
|
}
|
|
pmd_entry = mk_pmd(zero_page, vmf->vma->vm_page_prot);
|
|
pmd_entry = pmd_mkhuge(pmd_entry);
|
|
set_pmd_at(vmf->vma->vm_mm, pmd_addr, vmf->pmd, pmd_entry);
|
|
spin_unlock(ptl);
|
|
trace_dax_pmd_load_hole(inode, vmf, zero_page, *entry);
|
|
return VM_FAULT_NOPAGE;
|
|
|
|
fallback:
|
|
if (pgtable)
|
|
pte_free(vma->vm_mm, pgtable);
|
|
trace_dax_pmd_load_hole_fallback(inode, vmf, zero_page, *entry);
|
|
return VM_FAULT_FALLBACK;
|
|
}
|
|
|
|
static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp,
|
|
const struct iomap_ops *ops)
|
|
{
|
|
struct vm_area_struct *vma = vmf->vma;
|
|
struct address_space *mapping = vma->vm_file->f_mapping;
|
|
XA_STATE_ORDER(xas, &mapping->i_pages, vmf->pgoff, PMD_ORDER);
|
|
unsigned long pmd_addr = vmf->address & PMD_MASK;
|
|
bool write = vmf->flags & FAULT_FLAG_WRITE;
|
|
bool sync;
|
|
unsigned int iomap_flags = (write ? IOMAP_WRITE : 0) | IOMAP_FAULT;
|
|
struct inode *inode = mapping->host;
|
|
vm_fault_t result = VM_FAULT_FALLBACK;
|
|
struct iomap iomap = { .type = IOMAP_HOLE };
|
|
struct iomap srcmap = { .type = IOMAP_HOLE };
|
|
pgoff_t max_pgoff;
|
|
void *entry;
|
|
loff_t pos;
|
|
int error;
|
|
pfn_t pfn;
|
|
|
|
/*
|
|
* 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.
|
|
*/
|
|
max_pgoff = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE);
|
|
|
|
trace_dax_pmd_fault(inode, vmf, max_pgoff, 0);
|
|
|
|
/*
|
|
* Make sure that the faulting address's PMD offset (color) matches
|
|
* the PMD offset from the start of the file. This is necessary so
|
|
* that a PMD range in the page table overlaps exactly with a PMD
|
|
* range in the page cache.
|
|
*/
|
|
if ((vmf->pgoff & PG_PMD_COLOUR) !=
|
|
((vmf->address >> PAGE_SHIFT) & PG_PMD_COLOUR))
|
|
goto fallback;
|
|
|
|
/* 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;
|
|
|
|
if (xas.xa_index >= max_pgoff) {
|
|
result = VM_FAULT_SIGBUS;
|
|
goto out;
|
|
}
|
|
|
|
/* If the PMD would extend beyond the file size */
|
|
if ((xas.xa_index | PG_PMD_COLOUR) >= max_pgoff)
|
|
goto fallback;
|
|
|
|
/*
|
|
* grab_mapping_entry() will make sure we get an empty PMD entry,
|
|
* a zero PMD entry or a DAX PMD. If it can't (because a PTE
|
|
* entry is already in the array, for instance), it will return
|
|
* VM_FAULT_FALLBACK.
|
|
*/
|
|
entry = grab_mapping_entry(&xas, mapping, PMD_ORDER);
|
|
if (xa_is_internal(entry)) {
|
|
result = xa_to_internal(entry);
|
|
goto fallback;
|
|
}
|
|
|
|
/*
|
|
* It is possible, particularly with mixed reads & writes to private
|
|
* mappings, that we have raced with a PTE fault that overlaps with
|
|
* the PMD we need to set up. If so just return and the fault will be
|
|
* retried.
|
|
*/
|
|
if (!pmd_none(*vmf->pmd) && !pmd_trans_huge(*vmf->pmd) &&
|
|
!pmd_devmap(*vmf->pmd)) {
|
|
result = 0;
|
|
goto unlock_entry;
|
|
}
|
|
|
|
/*
|
|
* 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)xas.xa_index << PAGE_SHIFT;
|
|
error = ops->iomap_begin(inode, pos, PMD_SIZE, iomap_flags, &iomap,
|
|
&srcmap);
|
|
if (error)
|
|
goto unlock_entry;
|
|
|
|
if (iomap.offset + iomap.length < pos + PMD_SIZE)
|
|
goto finish_iomap;
|
|
|
|
sync = dax_fault_is_synchronous(iomap_flags, vma, &iomap);
|
|
|
|
switch (iomap.type) {
|
|
case IOMAP_MAPPED:
|
|
error = dax_iomap_pfn(&iomap, pos, PMD_SIZE, &pfn);
|
|
if (error < 0)
|
|
goto finish_iomap;
|
|
|
|
entry = dax_insert_entry(&xas, mapping, vmf, entry, pfn,
|
|
DAX_PMD, write && !sync);
|
|
|
|
/*
|
|
* If we are doing synchronous page fault and inode needs fsync,
|
|
* we can insert PMD into page tables only after that happens.
|
|
* Skip insertion for now and return the pfn so that caller can
|
|
* insert it after fsync is done.
|
|
*/
|
|
if (sync) {
|
|
if (WARN_ON_ONCE(!pfnp))
|
|
goto finish_iomap;
|
|
*pfnp = pfn;
|
|
result = VM_FAULT_NEEDDSYNC;
|
|
goto finish_iomap;
|
|
}
|
|
|
|
trace_dax_pmd_insert_mapping(inode, vmf, PMD_SIZE, pfn, entry);
|
|
result = vmf_insert_pfn_pmd(vmf, pfn, write);
|
|
break;
|
|
case IOMAP_UNWRITTEN:
|
|
case IOMAP_HOLE:
|
|
if (WARN_ON_ONCE(write))
|
|
break;
|
|
result = dax_pmd_load_hole(&xas, vmf, &iomap, &entry);
|
|
break;
|
|
default:
|
|
WARN_ON_ONCE(1);
|
|
break;
|
|
}
|
|
|
|
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);
|
|
}
|
|
unlock_entry:
|
|
dax_unlock_entry(&xas, entry);
|
|
fallback:
|
|
if (result == VM_FAULT_FALLBACK) {
|
|
split_huge_pmd(vma, vmf->pmd, vmf->address);
|
|
count_vm_event(THP_FAULT_FALLBACK);
|
|
}
|
|
out:
|
|
trace_dax_pmd_fault_done(inode, vmf, max_pgoff, result);
|
|
return result;
|
|
}
|
|
#else
|
|
static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp,
|
|
const struct iomap_ops *ops)
|
|
{
|
|
return VM_FAULT_FALLBACK;
|
|
}
|
|
#endif /* CONFIG_FS_DAX_PMD */
|
|
|
|
/**
|
|
* dax_iomap_fault - handle a page fault on a DAX file
|
|
* @vmf: The description of the fault
|
|
* @pe_size: Size of the page to fault in
|
|
* @pfnp: PFN to insert for synchronous faults if fsync is required
|
|
* @iomap_errp: Storage for detailed error code in case of error
|
|
* @ops: Iomap ops passed from the file system
|
|
*
|
|
* When a page fault occurs, filesystems may call this helper in
|
|
* their fault handler for DAX files. dax_iomap_fault() assumes the caller
|
|
* has done all the necessary locking for page fault to proceed
|
|
* successfully.
|
|
*/
|
|
vm_fault_t dax_iomap_fault(struct vm_fault *vmf, enum page_entry_size pe_size,
|
|
pfn_t *pfnp, int *iomap_errp, const struct iomap_ops *ops)
|
|
{
|
|
switch (pe_size) {
|
|
case PE_SIZE_PTE:
|
|
return dax_iomap_pte_fault(vmf, pfnp, iomap_errp, ops);
|
|
case PE_SIZE_PMD:
|
|
return dax_iomap_pmd_fault(vmf, pfnp, ops);
|
|
default:
|
|
return VM_FAULT_FALLBACK;
|
|
}
|
|
}
|
|
EXPORT_SYMBOL_GPL(dax_iomap_fault);
|
|
|
|
/*
|
|
* dax_insert_pfn_mkwrite - insert PTE or PMD entry into page tables
|
|
* @vmf: The description of the fault
|
|
* @pfn: PFN to insert
|
|
* @order: Order of entry to insert.
|
|
*
|
|
* This function inserts a writeable PTE or PMD entry into the page tables
|
|
* for an mmaped DAX file. It also marks the page cache entry as dirty.
|
|
*/
|
|
static vm_fault_t
|
|
dax_insert_pfn_mkwrite(struct vm_fault *vmf, pfn_t pfn, unsigned int order)
|
|
{
|
|
struct address_space *mapping = vmf->vma->vm_file->f_mapping;
|
|
XA_STATE_ORDER(xas, &mapping->i_pages, vmf->pgoff, order);
|
|
void *entry;
|
|
vm_fault_t ret;
|
|
|
|
xas_lock_irq(&xas);
|
|
entry = get_unlocked_entry(&xas, order);
|
|
/* Did we race with someone splitting entry or so? */
|
|
if (!entry || dax_is_conflict(entry) ||
|
|
(order == 0 && !dax_is_pte_entry(entry))) {
|
|
put_unlocked_entry(&xas, entry);
|
|
xas_unlock_irq(&xas);
|
|
trace_dax_insert_pfn_mkwrite_no_entry(mapping->host, vmf,
|
|
VM_FAULT_NOPAGE);
|
|
return VM_FAULT_NOPAGE;
|
|
}
|
|
xas_set_mark(&xas, PAGECACHE_TAG_DIRTY);
|
|
dax_lock_entry(&xas, entry);
|
|
xas_unlock_irq(&xas);
|
|
if (order == 0)
|
|
ret = vmf_insert_mixed_mkwrite(vmf->vma, vmf->address, pfn);
|
|
#ifdef CONFIG_FS_DAX_PMD
|
|
else if (order == PMD_ORDER)
|
|
ret = vmf_insert_pfn_pmd(vmf, pfn, FAULT_FLAG_WRITE);
|
|
#endif
|
|
else
|
|
ret = VM_FAULT_FALLBACK;
|
|
dax_unlock_entry(&xas, entry);
|
|
trace_dax_insert_pfn_mkwrite(mapping->host, vmf, ret);
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* dax_finish_sync_fault - finish synchronous page fault
|
|
* @vmf: The description of the fault
|
|
* @pe_size: Size of entry to be inserted
|
|
* @pfn: PFN to insert
|
|
*
|
|
* This function ensures that the file range touched by the page fault is
|
|
* stored persistently on the media and handles inserting of appropriate page
|
|
* table entry.
|
|
*/
|
|
vm_fault_t dax_finish_sync_fault(struct vm_fault *vmf,
|
|
enum page_entry_size pe_size, pfn_t pfn)
|
|
{
|
|
int err;
|
|
loff_t start = ((loff_t)vmf->pgoff) << PAGE_SHIFT;
|
|
unsigned int order = pe_order(pe_size);
|
|
size_t len = PAGE_SIZE << order;
|
|
|
|
err = vfs_fsync_range(vmf->vma->vm_file, start, start + len - 1, 1);
|
|
if (err)
|
|
return VM_FAULT_SIGBUS;
|
|
return dax_insert_pfn_mkwrite(vmf, pfn, order);
|
|
}
|
|
EXPORT_SYMBOL_GPL(dax_finish_sync_fault);
|