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![Matthew Wilcox (Oracle)](/assets/img/avatar_default.png)
This wrapper is no longer used. Remove it and all references to it. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
869 lines
26 KiB
C
869 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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#include <linux/shmem_fs.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 folio_batch may be altered by this function by removing
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* exceptional entries similar to what folio_batch_remove_exceptionals() does.
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*/
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static void truncate_folio_batch_exceptionals(struct address_space *mapping,
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struct folio_batch *fbatch, 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 < folio_batch_count(fbatch); j++)
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if (xa_is_value(fbatch->folios[j]))
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break;
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if (j == folio_batch_count(fbatch))
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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 < folio_batch_count(fbatch); i++) {
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struct folio *folio = fbatch->folios[i];
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pgoff_t index = indices[i];
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if (!xa_is_value(folio)) {
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fbatch->folios[j++] = folio;
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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, folio);
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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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fbatch->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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* folio_invalidate - Invalidate part or all of a folio.
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* @folio: The folio 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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* folio_invalidate() is called when all or part of the folio has become
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* invalidated by a truncate operation.
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*
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* folio_invalidate() 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 folio_invalidate(struct folio *folio, size_t offset, size_t length)
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{
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const struct address_space_operations *aops = folio->mapping->a_ops;
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if (aops->invalidate_folio)
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aops->invalidate_folio(folio, offset, length);
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}
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EXPORT_SYMBOL_GPL(folio_invalidate);
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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_folio(struct folio *folio)
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{
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if (folio_mapped(folio))
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unmap_mapping_folio(folio);
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if (folio_has_private(folio))
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folio_invalidate(folio, 0, folio_size(folio));
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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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folio_cancel_dirty(folio);
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folio_clear_mappedtodisk(folio);
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}
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int truncate_inode_folio(struct address_space *mapping, struct folio *folio)
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{
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if (folio->mapping != mapping)
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return -EIO;
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truncate_cleanup_folio(folio);
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filemap_remove_folio(folio);
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return 0;
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}
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/*
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* Handle partial folios. The folio may be entirely within the
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* range if a split has raced with us. If not, we zero the part of the
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* folio that's within the [start, end] range, and then split the folio if
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* it's large. split_page_range() will discard pages which now lie beyond
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* i_size, and we rely on the caller to discard pages which lie within a
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* newly created hole.
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*
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* Returns false if splitting failed so the caller can avoid
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* discarding the entire folio which is stubbornly unsplit.
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*/
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bool truncate_inode_partial_folio(struct folio *folio, loff_t start, loff_t end)
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{
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loff_t pos = folio_pos(folio);
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unsigned int offset, length;
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if (pos < start)
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offset = start - pos;
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else
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offset = 0;
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length = folio_size(folio);
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if (pos + length <= (u64)end)
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length = length - offset;
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else
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length = end + 1 - pos - offset;
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folio_wait_writeback(folio);
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if (length == folio_size(folio)) {
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truncate_inode_folio(folio->mapping, folio);
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return true;
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}
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/*
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* We may be zeroing pages we're about to discard, but it avoids
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* doing a complex calculation here, and then doing the zeroing
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* anyway if the page split fails.
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*/
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folio_zero_range(folio, offset, length);
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if (folio_has_private(folio))
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folio_invalidate(folio, offset, length);
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if (!folio_test_large(folio))
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return true;
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if (split_huge_page(&folio->page) == 0)
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return true;
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if (folio_test_dirty(folio))
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return false;
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truncate_inode_folio(folio->mapping, folio);
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return true;
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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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VM_BUG_ON_PAGE(PageTail(page), page);
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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_folio(mapping, page_folio(page));
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}
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EXPORT_SYMBOL(generic_error_remove_page);
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static long mapping_evict_folio(struct address_space *mapping,
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struct folio *folio)
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{
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if (folio_test_dirty(folio) || folio_test_writeback(folio))
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return 0;
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/* The refcount will be elevated if any page in the folio is mapped */
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if (folio_ref_count(folio) >
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folio_nr_pages(folio) + folio_has_private(folio) + 1)
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return 0;
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if (folio_has_private(folio) && !filemap_release_folio(folio, 0))
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return 0;
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return remove_mapping(mapping, folio);
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}
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/**
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* invalidate_inode_page() - Remove an unused page from the pagecache.
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* @page: The page to remove.
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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.
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*
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* Context: Page must be locked.
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* Return: The number of pages successfully removed.
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*/
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long invalidate_inode_page(struct page *page)
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{
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struct folio *folio = page_folio(page);
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struct address_space *mapping = folio_mapping(folio);
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/* The page may have been truncated before it was locked */
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if (!mapping)
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return 0;
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return mapping_evict_folio(mapping, folio);
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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 ->invalidate_folio() 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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struct folio_batch fbatch;
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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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struct folio *folio;
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bool same_folio;
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if (mapping_empty(mapping))
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return;
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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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folio_batch_init(&fbatch);
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index = start;
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while (index < end && find_lock_entries(mapping, index, end - 1,
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&fbatch, indices)) {
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index = indices[folio_batch_count(&fbatch) - 1] + 1;
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truncate_folio_batch_exceptionals(mapping, &fbatch, indices);
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for (i = 0; i < folio_batch_count(&fbatch); i++)
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truncate_cleanup_folio(fbatch.folios[i]);
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delete_from_page_cache_batch(mapping, &fbatch);
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for (i = 0; i < folio_batch_count(&fbatch); i++)
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folio_unlock(fbatch.folios[i]);
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folio_batch_release(&fbatch);
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cond_resched();
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}
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same_folio = (lstart >> PAGE_SHIFT) == (lend >> PAGE_SHIFT);
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folio = __filemap_get_folio(mapping, lstart >> PAGE_SHIFT, FGP_LOCK, 0);
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if (folio) {
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same_folio = lend < folio_pos(folio) + folio_size(folio);
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if (!truncate_inode_partial_folio(folio, lstart, lend)) {
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start = folio->index + folio_nr_pages(folio);
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if (same_folio)
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end = folio->index;
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}
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folio_unlock(folio);
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folio_put(folio);
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folio = NULL;
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}
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if (!same_folio)
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folio = __filemap_get_folio(mapping, lend >> PAGE_SHIFT,
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FGP_LOCK, 0);
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if (folio) {
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if (!truncate_inode_partial_folio(folio, lstart, lend))
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end = folio->index;
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folio_unlock(folio);
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folio_put(folio);
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}
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index = start;
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while (index < end) {
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cond_resched();
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if (!find_get_entries(mapping, index, end - 1, &fbatch,
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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 < folio_batch_count(&fbatch); i++) {
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struct folio *folio = fbatch.folios[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(folio))
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continue;
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folio_lock(folio);
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VM_BUG_ON_FOLIO(!folio_contains(folio, index), folio);
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folio_wait_writeback(folio);
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truncate_inode_folio(mapping, folio);
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folio_unlock(folio);
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index = folio_index(folio) + folio_nr_pages(folio) - 1;
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}
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truncate_folio_batch_exceptionals(mapping, &fbatch, indices);
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folio_batch_release(&fbatch);
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index++;
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}
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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 __filemap_remove_folio()) 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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/*
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* As truncation uses a lockless tree lookup, cycle
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* the tree lock to make sure any ongoing tree
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* modification that does not see AS_EXITING is
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* completed before starting the final truncate.
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*/
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xa_lock_irq(&mapping->i_pages);
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xa_unlock_irq(&mapping->i_pages);
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}
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truncate_inode_pages(mapping, 0);
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}
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EXPORT_SYMBOL(truncate_inode_pages_final);
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/**
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* invalidate_mapping_pagevec - Invalidate all the unlocked pages of one inode
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* @mapping: the address_space which holds the pages to invalidate
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* @start: the offset 'from' which to invalidate
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* @end: the offset 'to' which to invalidate (inclusive)
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* @nr_pagevec: invalidate failed page number for caller
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*
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* This helper is similar to invalidate_mapping_pages(), except that it accounts
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|
* for pages that are likely on a pagevec and counts them in @nr_pagevec, which
|
|
* will be used by the caller.
|
|
*/
|
|
unsigned long invalidate_mapping_pagevec(struct address_space *mapping,
|
|
pgoff_t start, pgoff_t end, unsigned long *nr_pagevec)
|
|
{
|
|
pgoff_t indices[PAGEVEC_SIZE];
|
|
struct folio_batch fbatch;
|
|
pgoff_t index = start;
|
|
unsigned long ret;
|
|
unsigned long count = 0;
|
|
int i;
|
|
|
|
folio_batch_init(&fbatch);
|
|
while (find_lock_entries(mapping, index, end, &fbatch, indices)) {
|
|
for (i = 0; i < folio_batch_count(&fbatch); i++) {
|
|
struct folio *folio = fbatch.folios[i];
|
|
|
|
/* We rely upon deletion not changing folio->index */
|
|
index = indices[i];
|
|
|
|
if (xa_is_value(folio)) {
|
|
count += invalidate_exceptional_entry(mapping,
|
|
index,
|
|
folio);
|
|
continue;
|
|
}
|
|
index += folio_nr_pages(folio) - 1;
|
|
|
|
ret = mapping_evict_folio(mapping, folio);
|
|
folio_unlock(folio);
|
|
/*
|
|
* Invalidation is a hint that the folio is no longer
|
|
* of interest and try to speed up its reclaim.
|
|
*/
|
|
if (!ret) {
|
|
deactivate_file_folio(folio);
|
|
/* It is likely on the pagevec of a remote CPU */
|
|
if (nr_pagevec)
|
|
(*nr_pagevec)++;
|
|
}
|
|
count += ret;
|
|
}
|
|
folio_batch_remove_exceptionals(&fbatch);
|
|
folio_batch_release(&fbatch);
|
|
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_pagevec(mapping, start, end, NULL);
|
|
}
|
|
EXPORT_SYMBOL(invalidate_mapping_pages);
|
|
|
|
/*
|
|
* This is like invalidate_inode_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_folio2(struct address_space *mapping,
|
|
struct folio *folio)
|
|
{
|
|
if (folio->mapping != mapping)
|
|
return 0;
|
|
|
|
if (folio_has_private(folio) &&
|
|
!filemap_release_folio(folio, GFP_KERNEL))
|
|
return 0;
|
|
|
|
spin_lock(&mapping->host->i_lock);
|
|
xa_lock_irq(&mapping->i_pages);
|
|
if (folio_test_dirty(folio))
|
|
goto failed;
|
|
|
|
BUG_ON(folio_has_private(folio));
|
|
__filemap_remove_folio(folio, NULL);
|
|
xa_unlock_irq(&mapping->i_pages);
|
|
if (mapping_shrinkable(mapping))
|
|
inode_add_lru(mapping->host);
|
|
spin_unlock(&mapping->host->i_lock);
|
|
|
|
filemap_free_folio(mapping, folio);
|
|
return 1;
|
|
failed:
|
|
xa_unlock_irq(&mapping->i_pages);
|
|
spin_unlock(&mapping->host->i_lock);
|
|
return 0;
|
|
}
|
|
|
|
static int folio_launder(struct address_space *mapping, struct folio *folio)
|
|
{
|
|
if (!folio_test_dirty(folio))
|
|
return 0;
|
|
if (folio->mapping != mapping || mapping->a_ops->launder_folio == NULL)
|
|
return 0;
|
|
return mapping->a_ops->launder_folio(folio);
|
|
}
|
|
|
|
/**
|
|
* 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 folio_batch fbatch;
|
|
pgoff_t index;
|
|
int i;
|
|
int ret = 0;
|
|
int ret2 = 0;
|
|
int did_range_unmap = 0;
|
|
|
|
if (mapping_empty(mapping))
|
|
return 0;
|
|
|
|
folio_batch_init(&fbatch);
|
|
index = start;
|
|
while (find_get_entries(mapping, index, end, &fbatch, indices)) {
|
|
for (i = 0; i < folio_batch_count(&fbatch); i++) {
|
|
struct folio *folio = fbatch.folios[i];
|
|
|
|
/* We rely upon deletion not changing folio->index */
|
|
index = indices[i];
|
|
|
|
if (xa_is_value(folio)) {
|
|
if (!invalidate_exceptional_entry2(mapping,
|
|
index, folio))
|
|
ret = -EBUSY;
|
|
continue;
|
|
}
|
|
|
|
if (!did_range_unmap && folio_mapped(folio)) {
|
|
/*
|
|
* If folio 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;
|
|
}
|
|
|
|
folio_lock(folio);
|
|
VM_BUG_ON_FOLIO(!folio_contains(folio, index), folio);
|
|
if (folio->mapping != mapping) {
|
|
folio_unlock(folio);
|
|
continue;
|
|
}
|
|
folio_wait_writeback(folio);
|
|
|
|
if (folio_mapped(folio))
|
|
unmap_mapping_folio(folio);
|
|
BUG_ON(folio_mapped(folio));
|
|
|
|
ret2 = folio_launder(mapping, folio);
|
|
if (ret2 == 0) {
|
|
if (!invalidate_complete_folio2(mapping, folio))
|
|
ret2 = -EBUSY;
|
|
}
|
|
if (ret2 < 0)
|
|
ret = ret2;
|
|
folio_unlock(folio);
|
|
}
|
|
folio_batch_remove_exceptionals(&fbatch);
|
|
folio_batch_release(&fbatch);
|
|
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);
|
|
}
|
|
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);
|