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/*
* 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;
spin_lock_irq(&mapping->tree_lock);
if (dax_mapping(mapping)) {
if (radix_tree_delete_item(&mapping->page_tree, index, entry))
mapping->nrexceptional--;
} else {
/*
* 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)
{
if (page_mapped(page)) {
unmap_mapping_range(mapping,
(loff_t)page->index << PAGE_SHIFT,
PAGE_SIZE, 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
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