| /* |
| * 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/buffer_head.h> /* grr. try_to_release_page, |
| do_invalidatepage */ |
| #include <linux/cleancache.h> |
| #include <linux/rmap.h> |
| #include "internal.h" |
| |
| static void clear_exceptional_entry(struct address_space *mapping, |
| pgoff_t index, void *entry) |
| { |
| struct radix_tree_node *node; |
| void **slot; |
| |
| /* Handled by shmem itself */ |
| if (shmem_mapping(mapping)) |
| return; |
| |
| if (dax_mapping(mapping)) { |
| dax_delete_mapping_entry(mapping, index); |
| return; |
| } |
| spin_lock_irq(&mapping->tree_lock); |
| /* |
| * Regular page slots are stabilized by the page lock even |
| * without the tree itself locked. These unlocked entries |
| * need verification under the tree lock. |
| */ |
| if (!__radix_tree_lookup(&mapping->page_tree, index, &node, |
| &slot)) |
| goto unlock; |
| if (*slot != entry) |
| goto unlock; |
| radix_tree_replace_slot(slot, NULL); |
| mapping->nrexceptional--; |
| if (!node) |
| goto unlock; |
| workingset_node_shadows_dec(node); |
| /* |
| * Don't track node without shadow entries. |
| * |
| * Avoid acquiring the list_lru lock if already untracked. |
| * The list_empty() test is safe as node->private_list is |
| * protected by mapping->tree_lock. |
| */ |
| if (!workingset_node_shadows(node) && |
| !list_empty(&node->private_list)) |
| list_lru_del(&workingset_shadow_nodes, |
| &node->private_list); |
| __radix_tree_delete_node(&mapping->page_tree, node); |
| unlock: |
| spin_unlock_irq(&mapping->tree_lock); |
| } |
| |
| /** |
| * do_invalidatepage - invalidate part or all of a page |
| * @page: the page which is affected |
| * @offset: start of the range to invalidate |
| * @length: length of the range to invalidate |
| * |
| * do_invalidatepage() is called when all or part of the page has become |
| * invalidated by a truncate operation. |
| * |
| * do_invalidatepage() 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 do_invalidatepage(struct page *page, unsigned int offset, |
| unsigned int length) |
| { |
| void (*invalidatepage)(struct page *, unsigned int, unsigned int); |
| |
| invalidatepage = page->mapping->a_ops->invalidatepage; |
| #ifdef CONFIG_BLOCK |
| if (!invalidatepage) |
| invalidatepage = block_invalidatepage; |
| #endif |
| if (invalidatepage) |
| (*invalidatepage)(page, offset, length); |
| } |
| |
| /* |
| * 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 bale 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 int |
| truncate_complete_page(struct address_space *mapping, struct page *page) |
| { |
| if (page->mapping != mapping) |
| return -EIO; |
| |
| if (page_has_private(page)) |
| do_invalidatepage(page, 0, PAGE_SIZE); |
| |
| /* |
| * 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. |
| */ |
| cancel_dirty_page(page); |
| ClearPageMappedToDisk(page); |
| delete_from_page_cache(page); |
| return 0; |
| } |
| |
| /* |
| * This is for invalidate_mapping_pages(). That function can be called at |
| * any time, and is not supposed to throw away dirty pages. But pages can |
| * be marked dirty at any time too, so use remove_mapping which safely |
| * discards clean, unused pages. |
| * |
| * Returns non-zero if the page was successfully invalidated. |
| */ |
| static int |
| invalidate_complete_page(struct address_space *mapping, struct page *page) |
| { |
| int ret; |
| |
| if (page->mapping != mapping) |
| return 0; |
| |
| if (page_has_private(page) && !try_to_release_page(page, 0)) |
| return 0; |
| |
| ret = remove_mapping(mapping, page); |
| |
| return ret; |
| } |
| |
| int truncate_inode_page(struct address_space *mapping, struct page *page) |
| { |
| loff_t holelen; |
| VM_BUG_ON_PAGE(PageTail(page), page); |
| |
| holelen = PageTransHuge(page) ? HPAGE_PMD_SIZE : PAGE_SIZE; |
| if (page_mapped(page)) { |
| unmap_mapping_range(mapping, |
| (loff_t)page->index << PAGE_SHIFT, |
| holelen, 0); |
| } |
| return truncate_complete_page(mapping, page); |
| } |
| |
| /* |
| * Used to get rid of pages on hardware memory corruption. |
| */ |
| int generic_error_remove_page(struct address_space *mapping, struct 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_page(mapping, page); |
| } |
| EXPORT_SYMBOL(generic_error_remove_page); |
| |
| /* |
| * Safely invalidate one page from its pagecache mapping. |
| * It only drops clean, unused pages. The page must be locked. |
| * |
| * Returns 1 if the page is successfully invalidated, otherwise 0. |
| */ |
| int invalidate_inode_page(struct page *page) |
| { |
| struct address_space *mapping = page_mapping(page); |
| if (!mapping) |
| return 0; |
| if (PageDirty(page) || PageWriteback(page)) |
| return 0; |
| if (page_mapped(page)) |
| return 0; |
| return invalidate_complete_page(mapping, page); |
| } |
| |
| /** |
| * 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 ->invalidatepage() 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 */ |
| unsigned int partial_start; /* inclusive */ |
| unsigned int partial_end; /* exclusive */ |
| struct pagevec pvec; |
| pgoff_t indices[PAGEVEC_SIZE]; |
| pgoff_t index; |
| int i; |
| |
| cleancache_invalidate_inode(mapping); |
| if (mapping->nrpages == 0 && mapping->nrexceptional == 0) |
| return; |
| |
| /* Offsets within partial pages */ |
| partial_start = lstart & (PAGE_SIZE - 1); |
| partial_end = (lend + 1) & (PAGE_SIZE - 1); |
| |
| /* |
| * '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; |
| |
| pagevec_init(&pvec, 0); |
| index = start; |
| while (index < end && pagevec_lookup_entries(&pvec, mapping, index, |
| min(end - index, (pgoff_t)PAGEVEC_SIZE), |
| indices)) { |
| for (i = 0; i < pagevec_count(&pvec); i++) { |
| struct page *page = pvec.pages[i]; |
| |
| /* We rely upon deletion not changing page->index */ |
| index = indices[i]; |
| if (index >= end) |
| break; |
| |
| if (radix_tree_exceptional_entry(page)) { |
| clear_exceptional_entry(mapping, index, page); |
| continue; |
| } |
| |
| if (!trylock_page(page)) |
| continue; |
| WARN_ON(page_to_index(page) != index); |
| if (PageWriteback(page)) { |
| unlock_page(page); |
| continue; |
| } |
| truncate_inode_page(mapping, page); |
| unlock_page(page); |
| } |
| pagevec_remove_exceptionals(&pvec); |
| pagevec_release(&pvec); |
| cond_resched(); |
| index++; |
| } |
| |
| if (partial_start) { |
| struct page *page = find_lock_page(mapping, start - 1); |
| if (page) { |
| unsigned int top = PAGE_SIZE; |
| if (start > end) { |
| /* Truncation within a single page */ |
| top = partial_end; |
| partial_end = 0; |
| } |
| wait_on_page_writeback(page); |
| zero_user_segment(page, partial_start, top); |
| cleancache_invalidate_page(mapping, page); |
| if (page_has_private(page)) |
| do_invalidatepage(page, partial_start, |
| top - partial_start); |
| unlock_page(page); |
| put_page(page); |
| } |
| } |
| if (partial_end) { |
| struct page *page = find_lock_page(mapping, end); |
| if (page) { |
| wait_on_page_writeback(page); |
| zero_user_segment(page, 0, partial_end); |
| cleancache_invalidate_page(mapping, page); |
| if (page_has_private(page)) |
| do_invalidatepage(page, 0, |
| partial_end); |
| unlock_page(page); |
| put_page(page); |
| } |
| } |
| /* |
| * If the truncation happened within a single page no pages |
| * will be released, just zeroed, so we can bail out now. |
| */ |
| if (start >= end) |
| return; |
| |
| index = start; |
| for ( ; ; ) { |
| cond_resched(); |
| if (!pagevec_lookup_entries(&pvec, mapping, index, |
| min(end - index, (pgoff_t)PAGEVEC_SIZE), indices)) { |
| /* If all gone from start onwards, we're done */ |
| if (index == start) |
| break; |
| /* Otherwise restart to make sure all gone */ |
| index = start; |
| continue; |
| } |
| if (index == start && indices[0] >= end) { |
| /* All gone out of hole to be punched, we're done */ |
| pagevec_remove_exceptionals(&pvec); |
| pagevec_release(&pvec); |
| break; |
| } |
| for (i = 0; i < pagevec_count(&pvec); i++) { |
| struct page *page = pvec.pages[i]; |
| |
| /* We rely upon deletion not changing page->index */ |
| index = indices[i]; |
| if (index >= end) { |
| /* Restart punch to make sure all gone */ |
| index = start - 1; |
| break; |
| } |
| |
| if (radix_tree_exceptional_entry(page)) { |
| clear_exceptional_entry(mapping, index, page); |
| continue; |
| } |
| |
| lock_page(page); |
| WARN_ON(page_to_index(page) != index); |
| wait_on_page_writeback(page); |
| truncate_inode_page(mapping, page); |
| unlock_page(page); |
| } |
| pagevec_remove_exceptionals(&pvec); |
| pagevec_release(&pvec); |
| index++; |
| } |
| cleancache_invalidate_inode(mapping); |
| } |
| 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_mutex. |
| * |
| * Note: When this function returns, there can be a page in the process of |
| * deletion (inside __delete_from_page_cache()) 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_mutex. |
| * |
| * 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) |
| { |
| unsigned long nrexceptional; |
| unsigned long nrpages; |
| |
| /* |
| * 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); |
| |
| /* |
| * When reclaim installs eviction entries, it increases |
| * nrexceptional first, then decreases nrpages. Make sure we see |
| * this in the right order or we might miss an entry. |
| */ |
| nrpages = mapping->nrpages; |
| smp_rmb(); |
| nrexceptional = mapping->nrexceptional; |
| |
| if (nrpages || nrexceptional) { |
| /* |
| * 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. |
| */ |
| spin_lock_irq(&mapping->tree_lock); |
| spin_unlock_irq(&mapping->tree_lock); |
| |
| truncate_inode_pages(mapping, 0); |
| } |
| } |
| EXPORT_SYMBOL(truncate_inode_pages_final); |
| |
| /** |
| * invalidate_mapping_pages - 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) |
| * |
| * This function only removes the unlocked pages, if you want to |
| * remove all the pages of one inode, you must call truncate_inode_pages. |
| * |
| * invalidate_mapping_pages() will not block on IO activity. It will not |
| * invalidate pages which are dirty, locked, under writeback or mapped into |
| * pagetables. |
| */ |
| unsigned long invalidate_mapping_pages(struct address_space *mapping, |
| pgoff_t start, pgoff_t end) |
| { |
| pgoff_t indices[PAGEVEC_SIZE]; |
| struct pagevec pvec; |
| pgoff_t index = start; |
| unsigned long ret; |
| unsigned long count = 0; |
| int i; |
| |
| pagevec_init(&pvec, 0); |
| while (index <= end && pagevec_lookup_entries(&pvec, mapping, index, |
| min(end - index, (pgoff_t)PAGEVEC_SIZE - 1) + 1, |
| indices)) { |
| for (i = 0; i < pagevec_count(&pvec); i++) { |
| struct page *page = pvec.pages[i]; |
| |
| /* We rely upon deletion not changing page->index */ |
| index = indices[i]; |
| if (index > end) |
| break; |
| |
| if (radix_tree_exceptional_entry(page)) { |
| clear_exceptional_entry(mapping, index, page); |
| continue; |
| } |
| |
| if (!trylock_page(page)) |
| continue; |
| |
| WARN_ON(page_to_index(page) != index); |
| |
| /* Middle of THP: skip */ |
| if (PageTransTail(page)) { |
| unlock_page(page); |
| continue; |
| } else if (PageTransHuge(page)) { |
| index += HPAGE_PMD_NR - 1; |
| i += HPAGE_PMD_NR - 1; |
| /* 'end' is in the middle of THP */ |
| if (index == round_down(end, HPAGE_PMD_NR)) |
| continue; |
| } |
| |
| ret = invalidate_inode_page(page); |
| unlock_page(page); |
| /* |
| * Invalidation is a hint that the page is no longer |
| * of interest and try to speed up its reclaim. |
| */ |
| if (!ret) |
| deactivate_file_page(page); |
| count += ret; |
| } |
| pagevec_remove_exceptionals(&pvec); |
| pagevec_release(&pvec); |
| cond_resched(); |
| index++; |
| } |
| return count; |
| } |
| EXPORT_SYMBOL(invalidate_mapping_pages); |
| |
| /* |
| * This is like invalidate_complete_page(), except it ignores the page's |
| * refcount. We do this because invalidate_inode_pages2() needs stronger |
| * invalidation guarantees, and cannot afford to leave pages behind because |
| * shrink_page_list() has a temp ref on them, or because they're transiently |
| * sitting in the lru_cache_add() pagevecs. |
| */ |
| static int |
| invalidate_complete_page2(struct address_space *mapping, struct page *page) |
| { |
| unsigned long flags; |
| |
| if (page->mapping != mapping) |
| return 0; |
| |
| if (page_has_private(page) && !try_to_release_page(page, GFP_KERNEL)) |
| return 0; |
| |
| spin_lock_irqsave(&mapping->tree_lock, flags); |
| if (PageDirty(page)) |
| goto failed; |
| |
| BUG_ON(page_has_private(page)); |
| __delete_from_page_cache(page, NULL); |
| spin_unlock_irqrestore(&mapping->tree_lock, flags); |
| |
| if (mapping->a_ops->freepage) |
| mapping->a_ops->freepage(page); |
| |
| put_page(page); /* pagecache ref */ |
| return 1; |
| failed: |
| spin_unlock_irqrestore(&mapping->tree_lock, flags); |
| return 0; |
| } |
| |
| static int do_launder_page(struct address_space *mapping, struct page *page) |
| { |
| if (!PageDirty(page)) |
| return 0; |
| if (page->mapping != mapping || mapping->a_ops->launder_page == NULL) |
| return 0; |
| return mapping->a_ops->launder_page(page); |
| } |
| |
| /** |
| * invalidate_inode_pages2_range - remove range of pages from an address_space |
| * @mapping: the address_space |
| * @start: the page offset 'from' which to invalidate |
| * @end: the page offset 'to' which to invalidate (inclusive) |
| * |
| * Any pages which are found to be mapped into pagetables are unmapped prior to |
| * invalidation. |
| * |
| * Returns -EBUSY if any pages could not be invalidated. |
| */ |
| int invalidate_inode_pages2_range(struct address_space *mapping, |
| pgoff_t start, pgoff_t end) |
| { |
| pgoff_t indices[PAGEVEC_SIZE]; |
| struct pagevec pvec; |
| pgoff_t index; |
| int i; |
| int ret = 0; |
| int ret2 = 0; |
| int did_range_unmap = 0; |
| |
| cleancache_invalidate_inode(mapping); |
| pagevec_init(&pvec, 0); |
| index = start; |
| while (index <= end && pagevec_lookup_entries(&pvec, mapping, index, |
| min(end - index, (pgoff_t)PAGEVEC_SIZE - 1) + 1, |
| indices)) { |
| for (i = 0; i < pagevec_count(&pvec); i++) { |
| struct page *page = pvec.pages[i]; |
| |
| /* We rely upon deletion not changing page->index */ |
| index = indices[i]; |
| if (index > end) |
| break; |
| |
| if (radix_tree_exceptional_entry(page)) { |
| clear_exceptional_entry(mapping, index, page); |
| continue; |
| } |
| |
| lock_page(page); |
| WARN_ON(page_to_index(page) != index); |
| if (page->mapping != mapping) { |
| unlock_page(page); |
| continue; |
| } |
| wait_on_page_writeback(page); |
| if (page_mapped(page)) { |
| if (!did_range_unmap) { |
| /* |
| * Zap the rest of the file in one hit. |
| */ |
| unmap_mapping_range(mapping, |
| (loff_t)index << PAGE_SHIFT, |
| (loff_t)(1 + end - index) |
| << PAGE_SHIFT, |
| 0); |
| did_range_unmap = 1; |
| } else { |
| /* |
| * Just zap this page |
| */ |
| unmap_mapping_range(mapping, |
| (loff_t)index << PAGE_SHIFT, |
| PAGE_SIZE, 0); |
| } |
| } |
| BUG_ON(page_mapped(page)); |
| ret2 = do_launder_page(mapping, page); |
| if (ret2 == 0) { |
| if (!invalidate_complete_page2(mapping, page)) |
| ret2 = -EBUSY; |
| } |
| if (ret2 < 0) |
| ret = ret2; |
| unlock_page(page); |
| } |
| pagevec_remove_exceptionals(&pvec); |
| pagevec_release(&pvec); |
| cond_resched(); |
| index++; |
| } |
| cleancache_invalidate_inode(mapping); |
| return ret; |
| } |
| EXPORT_SYMBOL_GPL(invalidate_inode_pages2_range); |
| |
| /** |
| * invalidate_inode_pages2 - remove all pages from an address_space |
| * @mapping: the address_space |
| * |
| * Any pages which are found to be mapped into pagetables are unmapped prior to |
| * invalidation. |
| * |
| * Returns -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_mutex 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_mutex - 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); |