| // 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" |
| |
| static void clear_shadow_entries(struct address_space *mapping, |
| unsigned long start, unsigned long max) |
| { |
| XA_STATE(xas, &mapping->i_pages, start); |
| struct folio *folio; |
| |
| /* Handled by shmem itself, or for DAX we do nothing. */ |
| if (shmem_mapping(mapping) || dax_mapping(mapping)) |
| return; |
| |
| xas_set_update(&xas, workingset_update_node); |
| |
| spin_lock(&mapping->host->i_lock); |
| xas_lock_irq(&xas); |
| |
| /* Clear all shadow entries from start to max */ |
| xas_for_each(&xas, folio, max) { |
| if (xa_is_value(folio)) |
| xas_store(&xas, NULL); |
| } |
| |
| xas_unlock_irq(&xas); |
| 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. |
| * Please note that indices[] has entries in ascending order as guaranteed by |
| * either find_get_entries() or find_lock_entries(). |
| */ |
| static void truncate_folio_batch_exceptionals(struct address_space *mapping, |
| struct folio_batch *fbatch, pgoff_t *indices) |
| { |
| XA_STATE(xas, &mapping->i_pages, indices[0]); |
| int nr = folio_batch_count(fbatch); |
| struct folio *folio; |
| int i, j; |
| |
| /* Handled by shmem itself */ |
| if (shmem_mapping(mapping)) |
| return; |
| |
| for (j = 0; j < nr; j++) |
| if (xa_is_value(fbatch->folios[j])) |
| break; |
| |
| if (j == nr) |
| return; |
| |
| if (dax_mapping(mapping)) { |
| for (i = j; i < nr; i++) { |
| if (xa_is_value(fbatch->folios[i])) |
| dax_delete_mapping_entry(mapping, indices[i]); |
| } |
| goto out; |
| } |
| |
| xas_set(&xas, indices[j]); |
| xas_set_update(&xas, workingset_update_node); |
| |
| spin_lock(&mapping->host->i_lock); |
| xas_lock_irq(&xas); |
| |
| xas_for_each(&xas, folio, indices[nr-1]) { |
| if (xa_is_value(folio)) |
| xas_store(&xas, NULL); |
| } |
| |
| xas_unlock_irq(&xas); |
| if (mapping_shrinkable(mapping)) |
| inode_add_lru(mapping->host); |
| spin_unlock(&mapping->host->i_lock); |
| out: |
| folio_batch_remove_exceptionals(fbatch); |
| } |
| |
| /** |
| * 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_needs_release(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); |
| } |
| |
| 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. |
| */ |
| if (!mapping_inaccessible(folio->mapping)) |
| folio_zero_range(folio, offset, length); |
| |
| if (folio_needs_release(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_folio(struct address_space *mapping, |
| struct folio *folio) |
| { |
| 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, folio); |
| } |
| EXPORT_SYMBOL(generic_error_remove_folio); |
| |
| /** |
| * mapping_evict_folio() - Remove an unused folio from the page-cache. |
| * @mapping: The mapping this folio belongs to. |
| * @folio: The folio to remove. |
| * |
| * Safely remove one folio from the page cache. |
| * It only drops clean, unused folios. |
| * |
| * Context: Folio must be locked. |
| * Return: The number of pages successfully removed. |
| */ |
| long mapping_evict_folio(struct address_space *mapping, struct folio *folio) |
| { |
| /* The page may have been truncated before it was locked */ |
| if (!mapping) |
| return 0; |
| 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); |
| } |
| |
| /** |
| * 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)) { |
| 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 (!IS_ERR(folio)) { |
| same_folio = lend < folio_pos(folio) + folio_size(folio); |
| if (!truncate_inode_partial_folio(folio, lstart, lend)) { |
| start = folio_next_index(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 (!IS_ERR(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 */ |
| |
| if (xa_is_value(folio)) |
| continue; |
| |
| folio_lock(folio); |
| VM_BUG_ON_FOLIO(!folio_contains(folio, indices[i]), folio); |
| folio_wait_writeback(folio); |
| truncate_inode_folio(mapping, folio); |
| folio_unlock(folio); |
| } |
| truncate_folio_batch_exceptionals(mapping, &fbatch, indices); |
| folio_batch_release(&fbatch); |
| } |
| } |
| 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); |
| |
| /** |
| * mapping_try_invalidate - Invalidate all the evictable folios of one inode |
| * @mapping: the address_space which holds the folios to invalidate |
| * @start: the offset 'from' which to invalidate |
| * @end: the offset 'to' which to invalidate (inclusive) |
| * @nr_failed: How many folio invalidations failed |
| * |
| * This function is similar to invalidate_mapping_pages(), except that it |
| * returns the number of folios which could not be evicted in @nr_failed. |
| */ |
| unsigned long mapping_try_invalidate(struct address_space *mapping, |
| pgoff_t start, pgoff_t end, unsigned long *nr_failed) |
| { |
| 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)) { |
| bool xa_has_values = false; |
| int nr = folio_batch_count(&fbatch); |
| |
| for (i = 0; i < nr; i++) { |
| struct folio *folio = fbatch.folios[i]; |
| |
| /* We rely upon deletion not changing folio->index */ |
| |
| if (xa_is_value(folio)) { |
| xa_has_values = true; |
| count++; |
| continue; |
| } |
| |
| 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); |
| /* Likely in the lru cache of a remote CPU */ |
| if (nr_failed) |
| (*nr_failed)++; |
| } |
| count += ret; |
| } |
| |
| if (xa_has_values) |
| clear_shadow_entries(mapping, indices[0], indices[nr-1]); |
| |
| folio_batch_remove_exceptionals(&fbatch); |
| folio_batch_release(&fbatch); |
| cond_resched(); |
| } |
| 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 indices that had their contents invalidated |
| */ |
| unsigned long invalidate_mapping_pages(struct address_space *mapping, |
| pgoff_t start, pgoff_t end) |
| { |
| return mapping_try_invalidate(mapping, start, end, NULL); |
| } |
| EXPORT_SYMBOL(invalidate_mapping_pages); |
| |
| /* |
| * This is like mapping_evict_folio(), except it ignores the folio's |
| * refcount. We do this because invalidate_inode_pages2() needs stronger |
| * invalidation guarantees, and cannot afford to leave folios behind because |
| * shrink_folio_list() has a temp ref on them, or because they're transiently |
| * sitting in the folio_add_lru() caches. |
| */ |
| 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)) { |
| bool xa_has_values = false; |
| int nr = folio_batch_count(&fbatch); |
| |
| for (i = 0; i < nr; i++) { |
| struct folio *folio = fbatch.folios[i]; |
| |
| /* We rely upon deletion not changing folio->index */ |
| |
| if (xa_is_value(folio)) { |
| xa_has_values = true; |
| if (dax_mapping(mapping) && |
| !dax_invalidate_mapping_entry_sync(mapping, indices[i])) |
| 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, indices[i], |
| (1 + end - indices[i]), false); |
| did_range_unmap = 1; |
| } |
| |
| folio_lock(folio); |
| if (unlikely(folio->mapping != mapping)) { |
| folio_unlock(folio); |
| continue; |
| } |
| VM_BUG_ON_FOLIO(!folio_contains(folio, indices[i]), folio); |
| 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); |
| } |
| |
| if (xa_has_values) |
| clear_shadow_entries(mapping, indices[0], indices[nr-1]); |
| |
| folio_batch_remove_exceptionals(&fbatch); |
| folio_batch_release(&fbatch); |
| cond_resched(); |
| } |
| /* |
| * 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 first |
| * write access to the page. The filesystem will update its per-block |
| * information 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 folio 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 folio *folio; |
| |
| 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; |
| |
| folio = filemap_lock_folio(inode->i_mapping, from / PAGE_SIZE); |
| /* Folio not cached? Nothing to do */ |
| if (IS_ERR(folio)) |
| return; |
| /* |
| * See folio_clear_dirty_for_io() for details why folio_mark_dirty() |
| * is needed. |
| */ |
| if (folio_mkclean(folio)) |
| folio_mark_dirty(folio); |
| |
| /* |
| * The post-eof range of the folio must be zeroed before it is exposed |
| * to the file. Writeback normally does this, but since i_size has been |
| * increased we handle it here. |
| */ |
| if (folio_test_dirty(folio)) { |
| unsigned int offset, end; |
| |
| offset = from - folio_pos(folio); |
| end = min_t(unsigned int, to - folio_pos(folio), |
| folio_size(folio)); |
| folio_zero_segment(folio, offset, end); |
| } |
| |
| folio_unlock(folio); |
| folio_put(folio); |
| } |
| 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); |