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![Johannes Weiner](/assets/img/avatar_default.png)
Historically (pre-2.5), the inode shrinker used to reclaim only empty inodes and skip over those that still contained page cache. This caused problems on highmem hosts: struct inode could put fill lowmem zones before the cache was getting reclaimed in the highmem zones. To address this, the inode shrinker started to strip page cache to facilitate reclaiming lowmem. However, this comes with its own set of problems: the shrinkers may drop actively used page cache just because the inodes are not currently open or dirty - think working with a large git tree. It further doesn't respect cgroup memory protection settings and can cause priority inversions between containers. Nowadays, the page cache also holds non-resident info for evicted cache pages in order to detect refaults. We've come to rely heavily on this data inside reclaim for protecting the cache workingset and driving swap behavior. We also use it to quantify and report workload health through psi. The latter in turn is used for fleet health monitoring, as well as driving automated memory sizing of workloads and containers, proactive reclaim and memory offloading schemes. The consequences of dropping page cache prematurely is that we're seeing subtle and not-so-subtle failures in all of the above-mentioned scenarios, with the workload generally entering unexpected thrashing states while losing the ability to reliably detect it. To fix this on non-highmem systems at least, going back to rotating inodes on the LRU isn't feasible. We've tried (commita76cf1a474
("mm: don't reclaim inodes with many attached pages")) and failed (commit69056ee6a8
("Revert "mm: don't reclaim inodes with many attached pages"")). The issue is mostly that shrinker pools attract pressure based on their size, and when objects get skipped the shrinkers remember this as deferred reclaim work. This accumulates excessive pressure on the remaining inodes, and we can quickly eat into heavily used ones, or dirty ones that require IO to reclaim, when there potentially is plenty of cold, clean cache around still. Instead, this patch keeps populated inodes off the inode LRU in the first place - just like an open file or dirty state would. An otherwise clean and unused inode then gets queued when the last cache entry disappears. This solves the problem without reintroducing the reclaim issues, and generally is a bit more scalable than having to wade through potentially hundreds of thousands of busy inodes. Locking is a bit tricky because the locks protecting the inode state (i_lock) and the inode LRU (lru_list.lock) don't nest inside the irq-safe page cache lock (i_pages.xa_lock). Page cache deletions are serialized through i_lock, taken before the i_pages lock, to make sure depopulated inodes are queued reliably. Additions may race with deletions, but we'll check again in the shrinker. If additions race with the shrinker itself, we're protected by the i_lock: if find_inode() or iput() win, the shrinker will bail on the elevated i_count or I_REFERENCED; if the shrinker wins and goes ahead with the inode, it will set I_FREEING and inhibit further igets(), which will cause the other side to create a new instance of the inode instead. Link: https://lkml.kernel.org/r/20210614211904.14420-4-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Roman Gushchin <guro@fb.com> Cc: Tejun Heo <tj@kernel.org> Cc: Dave Chinner <david@fromorbit.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
866 lines
26 KiB
C
866 lines
26 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* mm/truncate.c - code for taking down pages from address_spaces
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*
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* Copyright (C) 2002, Linus Torvalds
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*
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* 10Sep2002 Andrew Morton
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* Initial version.
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*/
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#include <linux/kernel.h>
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#include <linux/backing-dev.h>
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#include <linux/dax.h>
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#include <linux/gfp.h>
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#include <linux/mm.h>
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#include <linux/swap.h>
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#include <linux/export.h>
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#include <linux/pagemap.h>
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#include <linux/highmem.h>
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#include <linux/pagevec.h>
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#include <linux/task_io_accounting_ops.h>
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#include <linux/buffer_head.h> /* grr. try_to_release_page,
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do_invalidatepage */
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#include <linux/shmem_fs.h>
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#include <linux/cleancache.h>
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#include <linux/rmap.h>
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#include "internal.h"
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/*
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* Regular page slots are stabilized by the page lock even without the tree
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* itself locked. These unlocked entries need verification under the tree
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* lock.
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*/
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static inline void __clear_shadow_entry(struct address_space *mapping,
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pgoff_t index, void *entry)
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{
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XA_STATE(xas, &mapping->i_pages, index);
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xas_set_update(&xas, workingset_update_node);
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if (xas_load(&xas) != entry)
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return;
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xas_store(&xas, NULL);
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}
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static void clear_shadow_entry(struct address_space *mapping, pgoff_t index,
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void *entry)
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{
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spin_lock(&mapping->host->i_lock);
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xa_lock_irq(&mapping->i_pages);
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__clear_shadow_entry(mapping, index, entry);
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xa_unlock_irq(&mapping->i_pages);
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if (mapping_shrinkable(mapping))
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inode_add_lru(mapping->host);
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spin_unlock(&mapping->host->i_lock);
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}
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/*
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* Unconditionally remove exceptional entries. Usually called from truncate
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* path. Note that the pagevec may be altered by this function by removing
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* exceptional entries similar to what pagevec_remove_exceptionals does.
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*/
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static void truncate_exceptional_pvec_entries(struct address_space *mapping,
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struct pagevec *pvec, pgoff_t *indices)
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{
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int i, j;
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bool dax;
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/* Handled by shmem itself */
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if (shmem_mapping(mapping))
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return;
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for (j = 0; j < pagevec_count(pvec); j++)
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if (xa_is_value(pvec->pages[j]))
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break;
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if (j == pagevec_count(pvec))
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return;
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dax = dax_mapping(mapping);
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if (!dax) {
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spin_lock(&mapping->host->i_lock);
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xa_lock_irq(&mapping->i_pages);
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}
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for (i = j; i < pagevec_count(pvec); i++) {
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struct page *page = pvec->pages[i];
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pgoff_t index = indices[i];
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if (!xa_is_value(page)) {
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pvec->pages[j++] = page;
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continue;
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}
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if (unlikely(dax)) {
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dax_delete_mapping_entry(mapping, index);
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continue;
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}
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__clear_shadow_entry(mapping, index, page);
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}
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if (!dax) {
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xa_unlock_irq(&mapping->i_pages);
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if (mapping_shrinkable(mapping))
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inode_add_lru(mapping->host);
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spin_unlock(&mapping->host->i_lock);
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}
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pvec->nr = j;
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}
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/*
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* Invalidate exceptional entry if easily possible. This handles exceptional
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* entries for invalidate_inode_pages().
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*/
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static int invalidate_exceptional_entry(struct address_space *mapping,
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pgoff_t index, void *entry)
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{
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/* Handled by shmem itself, or for DAX we do nothing. */
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if (shmem_mapping(mapping) || dax_mapping(mapping))
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return 1;
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clear_shadow_entry(mapping, index, entry);
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return 1;
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}
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/*
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* Invalidate exceptional entry if clean. This handles exceptional entries for
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* invalidate_inode_pages2() so for DAX it evicts only clean entries.
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*/
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static int invalidate_exceptional_entry2(struct address_space *mapping,
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pgoff_t index, void *entry)
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{
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/* Handled by shmem itself */
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if (shmem_mapping(mapping))
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return 1;
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if (dax_mapping(mapping))
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return dax_invalidate_mapping_entry_sync(mapping, index);
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clear_shadow_entry(mapping, index, entry);
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return 1;
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}
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/**
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* do_invalidatepage - invalidate part or all of a page
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* @page: the page which is affected
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* @offset: start of the range to invalidate
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* @length: length of the range to invalidate
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*
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* do_invalidatepage() is called when all or part of the page has become
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* invalidated by a truncate operation.
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*
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* do_invalidatepage() does not have to release all buffers, but it must
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* ensure that no dirty buffer is left outside @offset and that no I/O
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* is underway against any of the blocks which are outside the truncation
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* point. Because the caller is about to free (and possibly reuse) those
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* blocks on-disk.
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*/
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void do_invalidatepage(struct page *page, unsigned int offset,
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unsigned int length)
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{
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void (*invalidatepage)(struct page *, unsigned int, unsigned int);
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invalidatepage = page->mapping->a_ops->invalidatepage;
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#ifdef CONFIG_BLOCK
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if (!invalidatepage)
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invalidatepage = block_invalidatepage;
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#endif
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if (invalidatepage)
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(*invalidatepage)(page, offset, length);
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}
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/*
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* If truncate cannot remove the fs-private metadata from the page, the page
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* becomes orphaned. It will be left on the LRU and may even be mapped into
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* user pagetables if we're racing with filemap_fault().
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*
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* We need to bail out if page->mapping is no longer equal to the original
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* mapping. This happens a) when the VM reclaimed the page while we waited on
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* its lock, b) when a concurrent invalidate_mapping_pages got there first and
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* c) when tmpfs swizzles a page between a tmpfs inode and swapper_space.
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*/
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static void truncate_cleanup_page(struct page *page)
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{
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if (page_mapped(page))
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unmap_mapping_page(page);
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if (page_has_private(page))
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do_invalidatepage(page, 0, thp_size(page));
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/*
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* Some filesystems seem to re-dirty the page even after
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* the VM has canceled the dirty bit (eg ext3 journaling).
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* Hence dirty accounting check is placed after invalidation.
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*/
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cancel_dirty_page(page);
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ClearPageMappedToDisk(page);
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}
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/*
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* This is for invalidate_mapping_pages(). That function can be called at
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* any time, and is not supposed to throw away dirty pages. But pages can
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* be marked dirty at any time too, so use remove_mapping which safely
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* discards clean, unused pages.
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*
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* Returns non-zero if the page was successfully invalidated.
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*/
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static int
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invalidate_complete_page(struct address_space *mapping, struct page *page)
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{
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int ret;
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if (page->mapping != mapping)
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return 0;
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if (page_has_private(page) && !try_to_release_page(page, 0))
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return 0;
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ret = remove_mapping(mapping, page);
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return ret;
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}
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int truncate_inode_page(struct address_space *mapping, struct page *page)
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{
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VM_BUG_ON_PAGE(PageTail(page), page);
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if (page->mapping != mapping)
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return -EIO;
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truncate_cleanup_page(page);
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delete_from_page_cache(page);
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return 0;
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}
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/*
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* Used to get rid of pages on hardware memory corruption.
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*/
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int generic_error_remove_page(struct address_space *mapping, struct page *page)
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{
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if (!mapping)
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return -EINVAL;
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/*
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* Only punch for normal data pages for now.
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* Handling other types like directories would need more auditing.
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*/
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if (!S_ISREG(mapping->host->i_mode))
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return -EIO;
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return truncate_inode_page(mapping, page);
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}
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EXPORT_SYMBOL(generic_error_remove_page);
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/*
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* Safely invalidate one page from its pagecache mapping.
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* It only drops clean, unused pages. The page must be locked.
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*
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* Returns 1 if the page is successfully invalidated, otherwise 0.
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*/
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int invalidate_inode_page(struct page *page)
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{
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struct address_space *mapping = page_mapping(page);
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if (!mapping)
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return 0;
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if (PageDirty(page) || PageWriteback(page))
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return 0;
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if (page_mapped(page))
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return 0;
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return invalidate_complete_page(mapping, page);
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}
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/**
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* truncate_inode_pages_range - truncate range of pages specified by start & end byte offsets
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* @mapping: mapping to truncate
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* @lstart: offset from which to truncate
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* @lend: offset to which to truncate (inclusive)
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*
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* Truncate the page cache, removing the pages that are between
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* specified offsets (and zeroing out partial pages
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* if lstart or lend + 1 is not page aligned).
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*
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* Truncate takes two passes - the first pass is nonblocking. It will not
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* block on page locks and it will not block on writeback. The second pass
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* will wait. This is to prevent as much IO as possible in the affected region.
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* The first pass will remove most pages, so the search cost of the second pass
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* is low.
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*
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* We pass down the cache-hot hint to the page freeing code. Even if the
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* mapping is large, it is probably the case that the final pages are the most
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* recently touched, and freeing happens in ascending file offset order.
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*
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* Note that since ->invalidatepage() accepts range to invalidate
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* truncate_inode_pages_range is able to handle cases where lend + 1 is not
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* page aligned properly.
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*/
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void truncate_inode_pages_range(struct address_space *mapping,
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loff_t lstart, loff_t lend)
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{
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pgoff_t start; /* inclusive */
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pgoff_t end; /* exclusive */
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unsigned int partial_start; /* inclusive */
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unsigned int partial_end; /* exclusive */
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struct pagevec pvec;
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pgoff_t indices[PAGEVEC_SIZE];
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pgoff_t index;
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int i;
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if (mapping_empty(mapping))
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goto out;
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/* Offsets within partial pages */
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partial_start = lstart & (PAGE_SIZE - 1);
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partial_end = (lend + 1) & (PAGE_SIZE - 1);
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/*
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* 'start' and 'end' always covers the range of pages to be fully
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* truncated. Partial pages are covered with 'partial_start' at the
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* start of the range and 'partial_end' at the end of the range.
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* Note that 'end' is exclusive while 'lend' is inclusive.
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*/
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start = (lstart + PAGE_SIZE - 1) >> PAGE_SHIFT;
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if (lend == -1)
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/*
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* lend == -1 indicates end-of-file so we have to set 'end'
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* to the highest possible pgoff_t and since the type is
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* unsigned we're using -1.
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*/
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end = -1;
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else
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end = (lend + 1) >> PAGE_SHIFT;
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pagevec_init(&pvec);
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index = start;
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while (index < end && find_lock_entries(mapping, index, end - 1,
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&pvec, indices)) {
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index = indices[pagevec_count(&pvec) - 1] + 1;
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truncate_exceptional_pvec_entries(mapping, &pvec, indices);
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for (i = 0; i < pagevec_count(&pvec); i++)
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truncate_cleanup_page(pvec.pages[i]);
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delete_from_page_cache_batch(mapping, &pvec);
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for (i = 0; i < pagevec_count(&pvec); i++)
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unlock_page(pvec.pages[i]);
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pagevec_release(&pvec);
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cond_resched();
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}
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if (partial_start) {
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struct page *page = find_lock_page(mapping, start - 1);
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if (page) {
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unsigned int top = PAGE_SIZE;
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if (start > end) {
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/* Truncation within a single page */
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top = partial_end;
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partial_end = 0;
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}
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wait_on_page_writeback(page);
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zero_user_segment(page, partial_start, top);
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cleancache_invalidate_page(mapping, page);
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if (page_has_private(page))
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do_invalidatepage(page, partial_start,
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top - partial_start);
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unlock_page(page);
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put_page(page);
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}
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}
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if (partial_end) {
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struct page *page = find_lock_page(mapping, end);
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if (page) {
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wait_on_page_writeback(page);
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zero_user_segment(page, 0, partial_end);
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cleancache_invalidate_page(mapping, page);
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if (page_has_private(page))
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do_invalidatepage(page, 0,
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partial_end);
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unlock_page(page);
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put_page(page);
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}
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}
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/*
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* If the truncation happened within a single page no pages
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* will be released, just zeroed, so we can bail out now.
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*/
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if (start >= end)
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goto out;
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index = start;
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for ( ; ; ) {
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cond_resched();
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if (!find_get_entries(mapping, index, end - 1, &pvec,
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indices)) {
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/* If all gone from start onwards, we're done */
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if (index == start)
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break;
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/* Otherwise restart to make sure all gone */
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index = start;
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continue;
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}
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for (i = 0; i < pagevec_count(&pvec); i++) {
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struct page *page = pvec.pages[i];
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/* We rely upon deletion not changing page->index */
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index = indices[i];
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if (xa_is_value(page))
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continue;
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lock_page(page);
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WARN_ON(page_to_index(page) != index);
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wait_on_page_writeback(page);
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truncate_inode_page(mapping, page);
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unlock_page(page);
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}
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truncate_exceptional_pvec_entries(mapping, &pvec, indices);
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pagevec_release(&pvec);
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index++;
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}
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out:
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cleancache_invalidate_inode(mapping);
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}
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EXPORT_SYMBOL(truncate_inode_pages_range);
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/**
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* truncate_inode_pages - truncate *all* the pages from an offset
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* @mapping: mapping to truncate
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* @lstart: offset from which to truncate
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*
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* Called under (and serialised by) inode->i_rwsem and
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* mapping->invalidate_lock.
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*
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* Note: When this function returns, there can be a page in the process of
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* deletion (inside __delete_from_page_cache()) in the specified range. Thus
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* mapping->nrpages can be non-zero when this function returns even after
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* truncation of the whole mapping.
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*/
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void truncate_inode_pages(struct address_space *mapping, loff_t lstart)
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{
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truncate_inode_pages_range(mapping, lstart, (loff_t)-1);
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}
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EXPORT_SYMBOL(truncate_inode_pages);
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/**
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* truncate_inode_pages_final - truncate *all* pages before inode dies
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* @mapping: mapping to truncate
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*
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* Called under (and serialized by) inode->i_rwsem.
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*
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* Filesystems have to use this in the .evict_inode path to inform the
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* VM that this is the final truncate and the inode is going away.
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*/
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void truncate_inode_pages_final(struct address_space *mapping)
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{
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/*
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* Page reclaim can not participate in regular inode lifetime
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* management (can't call iput()) and thus can race with the
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* inode teardown. Tell it when the address space is exiting,
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* so that it does not install eviction information after the
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* final truncate has begun.
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*/
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mapping_set_exiting(mapping);
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if (!mapping_empty(mapping)) {
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/*
|
|
* As truncation uses a lockless tree lookup, cycle
|
|
* the tree lock to make sure any ongoing tree
|
|
* modification that does not see AS_EXITING is
|
|
* completed before starting the final truncate.
|
|
*/
|
|
xa_lock_irq(&mapping->i_pages);
|
|
xa_unlock_irq(&mapping->i_pages);
|
|
}
|
|
|
|
/*
|
|
* Cleancache needs notification even if there are no pages or shadow
|
|
* entries.
|
|
*/
|
|
truncate_inode_pages(mapping, 0);
|
|
}
|
|
EXPORT_SYMBOL(truncate_inode_pages_final);
|
|
|
|
static unsigned long __invalidate_mapping_pages(struct address_space *mapping,
|
|
pgoff_t start, pgoff_t end, unsigned long *nr_pagevec)
|
|
{
|
|
pgoff_t indices[PAGEVEC_SIZE];
|
|
struct pagevec pvec;
|
|
pgoff_t index = start;
|
|
unsigned long ret;
|
|
unsigned long count = 0;
|
|
int i;
|
|
|
|
pagevec_init(&pvec);
|
|
while (find_lock_entries(mapping, index, end, &pvec, indices)) {
|
|
for (i = 0; i < pagevec_count(&pvec); i++) {
|
|
struct page *page = pvec.pages[i];
|
|
|
|
/* We rely upon deletion not changing page->index */
|
|
index = indices[i];
|
|
|
|
if (xa_is_value(page)) {
|
|
count += invalidate_exceptional_entry(mapping,
|
|
index,
|
|
page);
|
|
continue;
|
|
}
|
|
index += thp_nr_pages(page) - 1;
|
|
|
|
ret = invalidate_inode_page(page);
|
|
unlock_page(page);
|
|
/*
|
|
* Invalidation is a hint that the page is no longer
|
|
* of interest and try to speed up its reclaim.
|
|
*/
|
|
if (!ret) {
|
|
deactivate_file_page(page);
|
|
/* It is likely on the pagevec of a remote CPU */
|
|
if (nr_pagevec)
|
|
(*nr_pagevec)++;
|
|
}
|
|
count += ret;
|
|
}
|
|
pagevec_remove_exceptionals(&pvec);
|
|
pagevec_release(&pvec);
|
|
cond_resched();
|
|
index++;
|
|
}
|
|
return count;
|
|
}
|
|
|
|
/**
|
|
* invalidate_mapping_pages - Invalidate all clean, unlocked cache of one inode
|
|
* @mapping: the address_space which holds the cache to invalidate
|
|
* @start: the offset 'from' which to invalidate
|
|
* @end: the offset 'to' which to invalidate (inclusive)
|
|
*
|
|
* This function removes pages that are clean, unmapped and unlocked,
|
|
* as well as shadow entries. It will not block on IO activity.
|
|
*
|
|
* If you want to remove all the pages of one inode, regardless of
|
|
* their use and writeback state, use truncate_inode_pages().
|
|
*
|
|
* Return: the number of the cache entries that were invalidated
|
|
*/
|
|
unsigned long invalidate_mapping_pages(struct address_space *mapping,
|
|
pgoff_t start, pgoff_t end)
|
|
{
|
|
return __invalidate_mapping_pages(mapping, start, end, NULL);
|
|
}
|
|
EXPORT_SYMBOL(invalidate_mapping_pages);
|
|
|
|
/**
|
|
* invalidate_mapping_pagevec - Invalidate all the unlocked pages of one inode
|
|
* @mapping: the address_space which holds the pages to invalidate
|
|
* @start: the offset 'from' which to invalidate
|
|
* @end: the offset 'to' which to invalidate (inclusive)
|
|
* @nr_pagevec: invalidate failed page number for caller
|
|
*
|
|
* This helper is similar to invalidate_mapping_pages(), except that it accounts
|
|
* for pages that are likely on a pagevec and counts them in @nr_pagevec, which
|
|
* will be used by the caller.
|
|
*/
|
|
void invalidate_mapping_pagevec(struct address_space *mapping,
|
|
pgoff_t start, pgoff_t end, unsigned long *nr_pagevec)
|
|
{
|
|
__invalidate_mapping_pages(mapping, start, end, nr_pagevec);
|
|
}
|
|
|
|
/*
|
|
* This is like invalidate_complete_page(), except it ignores the page's
|
|
* refcount. We do this because invalidate_inode_pages2() needs stronger
|
|
* invalidation guarantees, and cannot afford to leave pages behind because
|
|
* shrink_page_list() has a temp ref on them, or because they're transiently
|
|
* sitting in the lru_cache_add() pagevecs.
|
|
*/
|
|
static int
|
|
invalidate_complete_page2(struct address_space *mapping, struct page *page)
|
|
{
|
|
if (page->mapping != mapping)
|
|
return 0;
|
|
|
|
if (page_has_private(page) && !try_to_release_page(page, GFP_KERNEL))
|
|
return 0;
|
|
|
|
spin_lock(&mapping->host->i_lock);
|
|
xa_lock_irq(&mapping->i_pages);
|
|
if (PageDirty(page))
|
|
goto failed;
|
|
|
|
BUG_ON(page_has_private(page));
|
|
__delete_from_page_cache(page, NULL);
|
|
xa_unlock_irq(&mapping->i_pages);
|
|
if (mapping_shrinkable(mapping))
|
|
inode_add_lru(mapping->host);
|
|
spin_unlock(&mapping->host->i_lock);
|
|
|
|
if (mapping->a_ops->freepage)
|
|
mapping->a_ops->freepage(page);
|
|
|
|
put_page(page); /* pagecache ref */
|
|
return 1;
|
|
failed:
|
|
xa_unlock_irq(&mapping->i_pages);
|
|
spin_unlock(&mapping->host->i_lock);
|
|
return 0;
|
|
}
|
|
|
|
static int do_launder_page(struct address_space *mapping, struct page *page)
|
|
{
|
|
if (!PageDirty(page))
|
|
return 0;
|
|
if (page->mapping != mapping || mapping->a_ops->launder_page == NULL)
|
|
return 0;
|
|
return mapping->a_ops->launder_page(page);
|
|
}
|
|
|
|
/**
|
|
* invalidate_inode_pages2_range - remove range of pages from an address_space
|
|
* @mapping: the address_space
|
|
* @start: the page offset 'from' which to invalidate
|
|
* @end: the page offset 'to' which to invalidate (inclusive)
|
|
*
|
|
* Any pages which are found to be mapped into pagetables are unmapped prior to
|
|
* invalidation.
|
|
*
|
|
* Return: -EBUSY if any pages could not be invalidated.
|
|
*/
|
|
int invalidate_inode_pages2_range(struct address_space *mapping,
|
|
pgoff_t start, pgoff_t end)
|
|
{
|
|
pgoff_t indices[PAGEVEC_SIZE];
|
|
struct pagevec pvec;
|
|
pgoff_t index;
|
|
int i;
|
|
int ret = 0;
|
|
int ret2 = 0;
|
|
int did_range_unmap = 0;
|
|
|
|
if (mapping_empty(mapping))
|
|
goto out;
|
|
|
|
pagevec_init(&pvec);
|
|
index = start;
|
|
while (find_get_entries(mapping, index, end, &pvec, indices)) {
|
|
for (i = 0; i < pagevec_count(&pvec); i++) {
|
|
struct page *page = pvec.pages[i];
|
|
|
|
/* We rely upon deletion not changing page->index */
|
|
index = indices[i];
|
|
|
|
if (xa_is_value(page)) {
|
|
if (!invalidate_exceptional_entry2(mapping,
|
|
index, page))
|
|
ret = -EBUSY;
|
|
continue;
|
|
}
|
|
|
|
if (!did_range_unmap && page_mapped(page)) {
|
|
/*
|
|
* If page is mapped, before taking its lock,
|
|
* zap the rest of the file in one hit.
|
|
*/
|
|
unmap_mapping_pages(mapping, index,
|
|
(1 + end - index), false);
|
|
did_range_unmap = 1;
|
|
}
|
|
|
|
lock_page(page);
|
|
WARN_ON(page_to_index(page) != index);
|
|
if (page->mapping != mapping) {
|
|
unlock_page(page);
|
|
continue;
|
|
}
|
|
wait_on_page_writeback(page);
|
|
|
|
if (page_mapped(page))
|
|
unmap_mapping_page(page);
|
|
BUG_ON(page_mapped(page));
|
|
|
|
ret2 = do_launder_page(mapping, page);
|
|
if (ret2 == 0) {
|
|
if (!invalidate_complete_page2(mapping, page))
|
|
ret2 = -EBUSY;
|
|
}
|
|
if (ret2 < 0)
|
|
ret = ret2;
|
|
unlock_page(page);
|
|
}
|
|
pagevec_remove_exceptionals(&pvec);
|
|
pagevec_release(&pvec);
|
|
cond_resched();
|
|
index++;
|
|
}
|
|
/*
|
|
* For DAX we invalidate page tables after invalidating page cache. We
|
|
* could invalidate page tables while invalidating each entry however
|
|
* that would be expensive. And doing range unmapping before doesn't
|
|
* work as we have no cheap way to find whether page cache entry didn't
|
|
* get remapped later.
|
|
*/
|
|
if (dax_mapping(mapping)) {
|
|
unmap_mapping_pages(mapping, start, end - start + 1, false);
|
|
}
|
|
out:
|
|
cleancache_invalidate_inode(mapping);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(invalidate_inode_pages2_range);
|
|
|
|
/**
|
|
* invalidate_inode_pages2 - remove all pages from an address_space
|
|
* @mapping: the address_space
|
|
*
|
|
* Any pages which are found to be mapped into pagetables are unmapped prior to
|
|
* invalidation.
|
|
*
|
|
* Return: -EBUSY if any pages could not be invalidated.
|
|
*/
|
|
int invalidate_inode_pages2(struct address_space *mapping)
|
|
{
|
|
return invalidate_inode_pages2_range(mapping, 0, -1);
|
|
}
|
|
EXPORT_SYMBOL_GPL(invalidate_inode_pages2);
|
|
|
|
/**
|
|
* truncate_pagecache - unmap and remove pagecache that has been truncated
|
|
* @inode: inode
|
|
* @newsize: new file size
|
|
*
|
|
* inode's new i_size must already be written before truncate_pagecache
|
|
* is called.
|
|
*
|
|
* This function should typically be called before the filesystem
|
|
* releases resources associated with the freed range (eg. deallocates
|
|
* blocks). This way, pagecache will always stay logically coherent
|
|
* with on-disk format, and the filesystem would not have to deal with
|
|
* situations such as writepage being called for a page that has already
|
|
* had its underlying blocks deallocated.
|
|
*/
|
|
void truncate_pagecache(struct inode *inode, loff_t newsize)
|
|
{
|
|
struct address_space *mapping = inode->i_mapping;
|
|
loff_t holebegin = round_up(newsize, PAGE_SIZE);
|
|
|
|
/*
|
|
* unmap_mapping_range is called twice, first simply for
|
|
* efficiency so that truncate_inode_pages does fewer
|
|
* single-page unmaps. However after this first call, and
|
|
* before truncate_inode_pages finishes, it is possible for
|
|
* private pages to be COWed, which remain after
|
|
* truncate_inode_pages finishes, hence the second
|
|
* unmap_mapping_range call must be made for correctness.
|
|
*/
|
|
unmap_mapping_range(mapping, holebegin, 0, 1);
|
|
truncate_inode_pages(mapping, newsize);
|
|
unmap_mapping_range(mapping, holebegin, 0, 1);
|
|
}
|
|
EXPORT_SYMBOL(truncate_pagecache);
|
|
|
|
/**
|
|
* truncate_setsize - update inode and pagecache for a new file size
|
|
* @inode: inode
|
|
* @newsize: new file size
|
|
*
|
|
* truncate_setsize updates i_size and performs pagecache truncation (if
|
|
* necessary) to @newsize. It will be typically be called from the filesystem's
|
|
* setattr function when ATTR_SIZE is passed in.
|
|
*
|
|
* Must be called with a lock serializing truncates and writes (generally
|
|
* i_rwsem but e.g. xfs uses a different lock) and before all filesystem
|
|
* specific block truncation has been performed.
|
|
*/
|
|
void truncate_setsize(struct inode *inode, loff_t newsize)
|
|
{
|
|
loff_t oldsize = inode->i_size;
|
|
|
|
i_size_write(inode, newsize);
|
|
if (newsize > oldsize)
|
|
pagecache_isize_extended(inode, oldsize, newsize);
|
|
truncate_pagecache(inode, newsize);
|
|
}
|
|
EXPORT_SYMBOL(truncate_setsize);
|
|
|
|
/**
|
|
* pagecache_isize_extended - update pagecache after extension of i_size
|
|
* @inode: inode for which i_size was extended
|
|
* @from: original inode size
|
|
* @to: new inode size
|
|
*
|
|
* Handle extension of inode size either caused by extending truncate or by
|
|
* write starting after current i_size. We mark the page straddling current
|
|
* i_size RO so that page_mkwrite() is called on the nearest write access to
|
|
* the page. This way filesystem can be sure that page_mkwrite() is called on
|
|
* the page before user writes to the page via mmap after the i_size has been
|
|
* changed.
|
|
*
|
|
* The function must be called after i_size is updated so that page fault
|
|
* coming after we unlock the page will already see the new i_size.
|
|
* The function must be called while we still hold i_rwsem - this not only
|
|
* makes sure i_size is stable but also that userspace cannot observe new
|
|
* i_size value before we are prepared to store mmap writes at new inode size.
|
|
*/
|
|
void pagecache_isize_extended(struct inode *inode, loff_t from, loff_t to)
|
|
{
|
|
int bsize = i_blocksize(inode);
|
|
loff_t rounded_from;
|
|
struct page *page;
|
|
pgoff_t index;
|
|
|
|
WARN_ON(to > inode->i_size);
|
|
|
|
if (from >= to || bsize == PAGE_SIZE)
|
|
return;
|
|
/* Page straddling @from will not have any hole block created? */
|
|
rounded_from = round_up(from, bsize);
|
|
if (to <= rounded_from || !(rounded_from & (PAGE_SIZE - 1)))
|
|
return;
|
|
|
|
index = from >> PAGE_SHIFT;
|
|
page = find_lock_page(inode->i_mapping, index);
|
|
/* Page not cached? Nothing to do */
|
|
if (!page)
|
|
return;
|
|
/*
|
|
* See clear_page_dirty_for_io() for details why set_page_dirty()
|
|
* is needed.
|
|
*/
|
|
if (page_mkclean(page))
|
|
set_page_dirty(page);
|
|
unlock_page(page);
|
|
put_page(page);
|
|
}
|
|
EXPORT_SYMBOL(pagecache_isize_extended);
|
|
|
|
/**
|
|
* truncate_pagecache_range - unmap and remove pagecache that is hole-punched
|
|
* @inode: inode
|
|
* @lstart: offset of beginning of hole
|
|
* @lend: offset of last byte of hole
|
|
*
|
|
* This function should typically be called before the filesystem
|
|
* releases resources associated with the freed range (eg. deallocates
|
|
* blocks). This way, pagecache will always stay logically coherent
|
|
* with on-disk format, and the filesystem would not have to deal with
|
|
* situations such as writepage being called for a page that has already
|
|
* had its underlying blocks deallocated.
|
|
*/
|
|
void truncate_pagecache_range(struct inode *inode, loff_t lstart, loff_t lend)
|
|
{
|
|
struct address_space *mapping = inode->i_mapping;
|
|
loff_t unmap_start = round_up(lstart, PAGE_SIZE);
|
|
loff_t unmap_end = round_down(1 + lend, PAGE_SIZE) - 1;
|
|
/*
|
|
* This rounding is currently just for example: unmap_mapping_range
|
|
* expands its hole outwards, whereas we want it to contract the hole
|
|
* inwards. However, existing callers of truncate_pagecache_range are
|
|
* doing their own page rounding first. Note that unmap_mapping_range
|
|
* allows holelen 0 for all, and we allow lend -1 for end of file.
|
|
*/
|
|
|
|
/*
|
|
* Unlike in truncate_pagecache, unmap_mapping_range is called only
|
|
* once (before truncating pagecache), and without "even_cows" flag:
|
|
* hole-punching should not remove private COWed pages from the hole.
|
|
*/
|
|
if ((u64)unmap_end > (u64)unmap_start)
|
|
unmap_mapping_range(mapping, unmap_start,
|
|
1 + unmap_end - unmap_start, 0);
|
|
truncate_inode_pages_range(mapping, lstart, lend);
|
|
}
|
|
EXPORT_SYMBOL(truncate_pagecache_range);
|