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-rw-r--r--mm/truncate.c867
1 files changed, 867 insertions, 0 deletions
diff --git a/mm/truncate.c b/mm/truncate.c
new file mode 100644
index 000000000..0d4dd233f
--- /dev/null
+++ b/mm/truncate.c
@@ -0,0 +1,867 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * mm/truncate.c - code for taking down pages from address_spaces
+ *
+ * Copyright (C) 2002, Linus Torvalds
+ *
+ * 10Sep2002 Andrew Morton
+ * Initial version.
+ */
+
+#include <linux/kernel.h>
+#include <linux/backing-dev.h>
+#include <linux/dax.h>
+#include <linux/gfp.h>
+#include <linux/mm.h>
+#include <linux/swap.h>
+#include <linux/export.h>
+#include <linux/pagemap.h>
+#include <linux/highmem.h>
+#include <linux/pagevec.h>
+#include <linux/task_io_accounting_ops.h>
+#include <linux/shmem_fs.h>
+#include <linux/rmap.h>
+#include "internal.h"
+
+/*
+ * Regular page slots are stabilized by the page lock even without the tree
+ * itself locked. These unlocked entries need verification under the tree
+ * lock.
+ */
+static inline void __clear_shadow_entry(struct address_space *mapping,
+ pgoff_t index, void *entry)
+{
+ XA_STATE(xas, &mapping->i_pages, index);
+
+ xas_set_update(&xas, workingset_update_node);
+ if (xas_load(&xas) != entry)
+ return;
+ xas_store(&xas, NULL);
+}
+
+static void clear_shadow_entry(struct address_space *mapping, pgoff_t index,
+ void *entry)
+{
+ spin_lock(&mapping->host->i_lock);
+ xa_lock_irq(&mapping->i_pages);
+ __clear_shadow_entry(mapping, index, entry);
+ xa_unlock_irq(&mapping->i_pages);
+ if (mapping_shrinkable(mapping))
+ inode_add_lru(mapping->host);
+ spin_unlock(&mapping->host->i_lock);
+}
+
+/*
+ * Unconditionally remove exceptional entries. Usually called from truncate
+ * path. Note that the folio_batch may be altered by this function by removing
+ * exceptional entries similar to what folio_batch_remove_exceptionals() does.
+ */
+static void truncate_folio_batch_exceptionals(struct address_space *mapping,
+ struct folio_batch *fbatch, pgoff_t *indices)
+{
+ int i, j;
+ bool dax;
+
+ /* Handled by shmem itself */
+ if (shmem_mapping(mapping))
+ return;
+
+ for (j = 0; j < folio_batch_count(fbatch); j++)
+ if (xa_is_value(fbatch->folios[j]))
+ break;
+
+ if (j == folio_batch_count(fbatch))
+ return;
+
+ dax = dax_mapping(mapping);
+ if (!dax) {
+ spin_lock(&mapping->host->i_lock);
+ xa_lock_irq(&mapping->i_pages);
+ }
+
+ for (i = j; i < folio_batch_count(fbatch); i++) {
+ struct folio *folio = fbatch->folios[i];
+ pgoff_t index = indices[i];
+
+ if (!xa_is_value(folio)) {
+ fbatch->folios[j++] = folio;
+ continue;
+ }
+
+ if (unlikely(dax)) {
+ dax_delete_mapping_entry(mapping, index);
+ continue;
+ }
+
+ __clear_shadow_entry(mapping, index, folio);
+ }
+
+ if (!dax) {
+ xa_unlock_irq(&mapping->i_pages);
+ if (mapping_shrinkable(mapping))
+ inode_add_lru(mapping->host);
+ spin_unlock(&mapping->host->i_lock);
+ }
+ fbatch->nr = j;
+}
+
+/*
+ * Invalidate exceptional entry if easily possible. This handles exceptional
+ * entries for invalidate_inode_pages().
+ */
+static int invalidate_exceptional_entry(struct address_space *mapping,
+ pgoff_t index, void *entry)
+{
+ /* Handled by shmem itself, or for DAX we do nothing. */
+ if (shmem_mapping(mapping) || dax_mapping(mapping))
+ return 1;
+ clear_shadow_entry(mapping, index, entry);
+ return 1;
+}
+
+/*
+ * Invalidate exceptional entry if clean. This handles exceptional entries for
+ * invalidate_inode_pages2() so for DAX it evicts only clean entries.
+ */
+static int invalidate_exceptional_entry2(struct address_space *mapping,
+ pgoff_t index, void *entry)
+{
+ /* Handled by shmem itself */
+ if (shmem_mapping(mapping))
+ return 1;
+ if (dax_mapping(mapping))
+ return dax_invalidate_mapping_entry_sync(mapping, index);
+ clear_shadow_entry(mapping, index, entry);
+ return 1;
+}
+
+/**
+ * folio_invalidate - Invalidate part or all of a folio.
+ * @folio: The folio which is affected.
+ * @offset: start of the range to invalidate
+ * @length: length of the range to invalidate
+ *
+ * folio_invalidate() is called when all or part of the folio has become
+ * invalidated by a truncate operation.
+ *
+ * folio_invalidate() does not have to release all buffers, but it must
+ * ensure that no dirty buffer is left outside @offset and that no I/O
+ * is underway against any of the blocks which are outside the truncation
+ * point. Because the caller is about to free (and possibly reuse) those
+ * blocks on-disk.
+ */
+void folio_invalidate(struct folio *folio, size_t offset, size_t length)
+{
+ const struct address_space_operations *aops = folio->mapping->a_ops;
+
+ if (aops->invalidate_folio)
+ aops->invalidate_folio(folio, offset, length);
+}
+EXPORT_SYMBOL_GPL(folio_invalidate);
+
+/*
+ * If truncate cannot remove the fs-private metadata from the page, the page
+ * becomes orphaned. It will be left on the LRU and may even be mapped into
+ * user pagetables if we're racing with filemap_fault().
+ *
+ * We need to bail out if page->mapping is no longer equal to the original
+ * mapping. This happens a) when the VM reclaimed the page while we waited on
+ * its lock, b) when a concurrent invalidate_mapping_pages got there first and
+ * c) when tmpfs swizzles a page between a tmpfs inode and swapper_space.
+ */
+static void truncate_cleanup_folio(struct folio *folio)
+{
+ if (folio_mapped(folio))
+ unmap_mapping_folio(folio);
+
+ if (folio_has_private(folio))
+ folio_invalidate(folio, 0, folio_size(folio));
+
+ /*
+ * Some filesystems seem to re-dirty the page even after
+ * the VM has canceled the dirty bit (eg ext3 journaling).
+ * Hence dirty accounting check is placed after invalidation.
+ */
+ folio_cancel_dirty(folio);
+ folio_clear_mappedtodisk(folio);
+}
+
+int truncate_inode_folio(struct address_space *mapping, struct folio *folio)
+{
+ if (folio->mapping != mapping)
+ return -EIO;
+
+ truncate_cleanup_folio(folio);
+ filemap_remove_folio(folio);
+ return 0;
+}
+
+/*
+ * Handle partial folios. The folio may be entirely within the
+ * range if a split has raced with us. If not, we zero the part of the
+ * folio that's within the [start, end] range, and then split the folio if
+ * it's large. split_page_range() will discard pages which now lie beyond
+ * i_size, and we rely on the caller to discard pages which lie within a
+ * newly created hole.
+ *
+ * Returns false if splitting failed so the caller can avoid
+ * discarding the entire folio which is stubbornly unsplit.
+ */
+bool truncate_inode_partial_folio(struct folio *folio, loff_t start, loff_t end)
+{
+ loff_t pos = folio_pos(folio);
+ unsigned int offset, length;
+
+ if (pos < start)
+ offset = start - pos;
+ else
+ offset = 0;
+ length = folio_size(folio);
+ if (pos + length <= (u64)end)
+ length = length - offset;
+ else
+ length = end + 1 - pos - offset;
+
+ folio_wait_writeback(folio);
+ if (length == folio_size(folio)) {
+ truncate_inode_folio(folio->mapping, folio);
+ return true;
+ }
+
+ /*
+ * We may be zeroing pages we're about to discard, but it avoids
+ * doing a complex calculation here, and then doing the zeroing
+ * anyway if the page split fails.
+ */
+ folio_zero_range(folio, offset, length);
+
+ if (folio_has_private(folio))
+ folio_invalidate(folio, offset, length);
+ if (!folio_test_large(folio))
+ return true;
+ if (split_folio(folio) == 0)
+ return true;
+ if (folio_test_dirty(folio))
+ return false;
+ truncate_inode_folio(folio->mapping, folio);
+ return true;
+}
+
+/*
+ * Used to get rid of pages on hardware memory corruption.
+ */
+int generic_error_remove_page(struct address_space *mapping, struct page *page)
+{
+ VM_BUG_ON_PAGE(PageTail(page), page);
+
+ if (!mapping)
+ return -EINVAL;
+ /*
+ * Only punch for normal data pages for now.
+ * Handling other types like directories would need more auditing.
+ */
+ if (!S_ISREG(mapping->host->i_mode))
+ return -EIO;
+ return truncate_inode_folio(mapping, page_folio(page));
+}
+EXPORT_SYMBOL(generic_error_remove_page);
+
+static long mapping_evict_folio(struct address_space *mapping,
+ struct folio *folio)
+{
+ if (folio_test_dirty(folio) || folio_test_writeback(folio))
+ return 0;
+ /* The refcount will be elevated if any page in the folio is mapped */
+ if (folio_ref_count(folio) >
+ folio_nr_pages(folio) + folio_has_private(folio) + 1)
+ return 0;
+ if (!filemap_release_folio(folio, 0))
+ return 0;
+
+ return remove_mapping(mapping, folio);
+}
+
+/**
+ * invalidate_inode_page() - Remove an unused page from the pagecache.
+ * @page: The page to remove.
+ *
+ * Safely invalidate one page from its pagecache mapping.
+ * It only drops clean, unused pages.
+ *
+ * Context: Page must be locked.
+ * Return: The number of pages successfully removed.
+ */
+long invalidate_inode_page(struct page *page)
+{
+ struct folio *folio = page_folio(page);
+ struct address_space *mapping = folio_mapping(folio);
+
+ /* The page may have been truncated before it was locked */
+ if (!mapping)
+ return 0;
+ return mapping_evict_folio(mapping, folio);
+}
+
+/**
+ * truncate_inode_pages_range - truncate range of pages specified by start & end byte offsets
+ * @mapping: mapping to truncate
+ * @lstart: offset from which to truncate
+ * @lend: offset to which to truncate (inclusive)
+ *
+ * Truncate the page cache, removing the pages that are between
+ * specified offsets (and zeroing out partial pages
+ * if lstart or lend + 1 is not page aligned).
+ *
+ * Truncate takes two passes - the first pass is nonblocking. It will not
+ * block on page locks and it will not block on writeback. The second pass
+ * will wait. This is to prevent as much IO as possible in the affected region.
+ * The first pass will remove most pages, so the search cost of the second pass
+ * is low.
+ *
+ * We pass down the cache-hot hint to the page freeing code. Even if the
+ * mapping is large, it is probably the case that the final pages are the most
+ * recently touched, and freeing happens in ascending file offset order.
+ *
+ * Note that since ->invalidate_folio() accepts range to invalidate
+ * truncate_inode_pages_range is able to handle cases where lend + 1 is not
+ * page aligned properly.
+ */
+void truncate_inode_pages_range(struct address_space *mapping,
+ loff_t lstart, loff_t lend)
+{
+ pgoff_t start; /* inclusive */
+ pgoff_t end; /* exclusive */
+ struct folio_batch fbatch;
+ pgoff_t indices[PAGEVEC_SIZE];
+ pgoff_t index;
+ int i;
+ struct folio *folio;
+ bool same_folio;
+
+ if (mapping_empty(mapping))
+ return;
+
+ /*
+ * 'start' and 'end' always covers the range of pages to be fully
+ * truncated. Partial pages are covered with 'partial_start' at the
+ * start of the range and 'partial_end' at the end of the range.
+ * Note that 'end' is exclusive while 'lend' is inclusive.
+ */
+ start = (lstart + PAGE_SIZE - 1) >> PAGE_SHIFT;
+ if (lend == -1)
+ /*
+ * lend == -1 indicates end-of-file so we have to set 'end'
+ * to the highest possible pgoff_t and since the type is
+ * unsigned we're using -1.
+ */
+ end = -1;
+ else
+ end = (lend + 1) >> PAGE_SHIFT;
+
+ folio_batch_init(&fbatch);
+ index = start;
+ while (index < end && find_lock_entries(mapping, index, end - 1,
+ &fbatch, indices)) {
+ index = indices[folio_batch_count(&fbatch) - 1] + 1;
+ truncate_folio_batch_exceptionals(mapping, &fbatch, indices);
+ for (i = 0; i < folio_batch_count(&fbatch); i++)
+ truncate_cleanup_folio(fbatch.folios[i]);
+ delete_from_page_cache_batch(mapping, &fbatch);
+ for (i = 0; i < folio_batch_count(&fbatch); i++)
+ folio_unlock(fbatch.folios[i]);
+ folio_batch_release(&fbatch);
+ cond_resched();
+ }
+
+ same_folio = (lstart >> PAGE_SHIFT) == (lend >> PAGE_SHIFT);
+ folio = __filemap_get_folio(mapping, lstart >> PAGE_SHIFT, FGP_LOCK, 0);
+ if (folio) {
+ same_folio = lend < folio_pos(folio) + folio_size(folio);
+ if (!truncate_inode_partial_folio(folio, lstart, lend)) {
+ start = folio->index + folio_nr_pages(folio);
+ if (same_folio)
+ end = folio->index;
+ }
+ folio_unlock(folio);
+ folio_put(folio);
+ folio = NULL;
+ }
+
+ if (!same_folio)
+ folio = __filemap_get_folio(mapping, lend >> PAGE_SHIFT,
+ FGP_LOCK, 0);
+ if (folio) {
+ if (!truncate_inode_partial_folio(folio, lstart, lend))
+ end = folio->index;
+ folio_unlock(folio);
+ folio_put(folio);
+ }
+
+ index = start;
+ while (index < end) {
+ cond_resched();
+ if (!find_get_entries(mapping, index, end - 1, &fbatch,
+ indices)) {
+ /* If all gone from start onwards, we're done */
+ if (index == start)
+ break;
+ /* Otherwise restart to make sure all gone */
+ index = start;
+ continue;
+ }
+
+ for (i = 0; i < folio_batch_count(&fbatch); i++) {
+ struct folio *folio = fbatch.folios[i];
+
+ /* We rely upon deletion not changing page->index */
+ index = indices[i];
+
+ if (xa_is_value(folio))
+ continue;
+
+ folio_lock(folio);
+ VM_BUG_ON_FOLIO(!folio_contains(folio, index), folio);
+ folio_wait_writeback(folio);
+ truncate_inode_folio(mapping, folio);
+ folio_unlock(folio);
+ index = folio_index(folio) + folio_nr_pages(folio) - 1;
+ }
+ truncate_folio_batch_exceptionals(mapping, &fbatch, indices);
+ folio_batch_release(&fbatch);
+ index++;
+ }
+}
+EXPORT_SYMBOL(truncate_inode_pages_range);
+
+/**
+ * truncate_inode_pages - truncate *all* the pages from an offset
+ * @mapping: mapping to truncate
+ * @lstart: offset from which to truncate
+ *
+ * Called under (and serialised by) inode->i_rwsem and
+ * mapping->invalidate_lock.
+ *
+ * Note: When this function returns, there can be a page in the process of
+ * deletion (inside __filemap_remove_folio()) in the specified range. Thus
+ * mapping->nrpages can be non-zero when this function returns even after
+ * truncation of the whole mapping.
+ */
+void truncate_inode_pages(struct address_space *mapping, loff_t lstart)
+{
+ truncate_inode_pages_range(mapping, lstart, (loff_t)-1);
+}
+EXPORT_SYMBOL(truncate_inode_pages);
+
+/**
+ * truncate_inode_pages_final - truncate *all* pages before inode dies
+ * @mapping: mapping to truncate
+ *
+ * Called under (and serialized by) inode->i_rwsem.
+ *
+ * Filesystems have to use this in the .evict_inode path to inform the
+ * VM that this is the final truncate and the inode is going away.
+ */
+void truncate_inode_pages_final(struct address_space *mapping)
+{
+ /*
+ * Page reclaim can not participate in regular inode lifetime
+ * management (can't call iput()) and thus can race with the
+ * inode teardown. Tell it when the address space is exiting,
+ * so that it does not install eviction information after the
+ * final truncate has begun.
+ */
+ mapping_set_exiting(mapping);
+
+ if (!mapping_empty(mapping)) {
+ /*
+ * 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);
+ }
+
+ truncate_inode_pages(mapping, 0);
+}
+EXPORT_SYMBOL(truncate_inode_pages_final);
+
+/**
+ * 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.
+ */
+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 (!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);