*
* Copyright (C) 2002, Linus Torvalds
*
- * 10Sep2002 akpm@zip.com.au
+ * 10Sep2002 Andrew Morton
* Initial version.
*/
#include <linux/kernel.h>
+#include <linux/backing-dev.h>
#include <linux/mm.h>
+#include <linux/swap.h>
#include <linux/module.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 "internal.h"
+/**
+ * do_invalidatepage - invalidate part or all of a page
+ * @page: the page which is affected
+ * @offset: the index of the truncation point
+ *
+ * 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 long offset)
+{
+ void (*invalidatepage)(struct page *, unsigned long);
+ invalidatepage = page->mapping->a_ops->invalidatepage;
+#ifdef CONFIG_BLOCK
+ if (!invalidatepage)
+ invalidatepage = block_invalidatepage;
+#endif
+ if (invalidatepage)
+ (*invalidatepage)(page, offset);
+}
+
static inline void truncate_partial_page(struct page *page, unsigned partial)
{
- memclear_highpage_flush(page, partial, PAGE_CACHE_SIZE-partial);
- if (PagePrivate(page))
+ zero_user_segment(page, partial, PAGE_CACHE_SIZE);
+ if (page_has_private(page))
do_invalidatepage(page, partial);
}
+/*
+ * This cancels just the dirty bit on the kernel page itself, it
+ * does NOT actually remove dirty bits on any mmap's that may be
+ * around. It also leaves the page tagged dirty, so any sync
+ * activity will still find it on the dirty lists, and in particular,
+ * clear_page_dirty_for_io() will still look at the dirty bits in
+ * the VM.
+ *
+ * Doing this should *normally* only ever be done when a page
+ * is truncated, and is not actually mapped anywhere at all. However,
+ * fs/buffer.c does this when it notices that somebody has cleaned
+ * out all the buffers on a page without actually doing it through
+ * the VM. Can you say "ext3 is horribly ugly"? Tought you could.
+ */
+void cancel_dirty_page(struct page *page, unsigned int account_size)
+{
+ if (TestClearPageDirty(page)) {
+ struct address_space *mapping = page->mapping;
+ if (mapping && mapping_cap_account_dirty(mapping)) {
+ dec_zone_page_state(page, NR_FILE_DIRTY);
+ dec_bdi_stat(mapping->backing_dev_info,
+ BDI_RECLAIMABLE);
+ if (account_size)
+ task_io_account_cancelled_write(account_size);
+ }
+ }
+}
+EXPORT_SYMBOL(cancel_dirty_page);
+
/*
* If truncate cannot remove the fs-private metadata from the page, the page
- * becomes anonymous. It will be left on the LRU and may even be mapped into
- * user pagetables if we're racing with filemap_nopage().
+ * 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_inode_pages got there first and
+ * 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
+static int
truncate_complete_page(struct address_space *mapping, struct page *page)
{
if (page->mapping != mapping)
- return;
+ return -EIO;
- if (PagePrivate(page))
+ if (page_has_private(page))
do_invalidatepage(page, 0);
- clear_page_dirty(page);
- ClearPageUptodate(page);
- ClearPageMappedToDisk(page);
+ cancel_dirty_page(page, PAGE_CACHE_SIZE);
+
+ clear_page_mlock(page);
remove_from_page_cache(page);
+ ClearPageMappedToDisk(page);
page_cache_release(page); /* pagecache ref */
+ return 0;
}
/*
- * This is for invalidate_inode_pages(). That function can be called at
+ * 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 we re-check the dirtiness inside
- * ->tree_lock. That provides exclusion against the __set_page_dirty
- * functions.
+ * 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 (PagePrivate(page) && !try_to_release_page(page, 0))
+ if (page_has_private(page) && !try_to_release_page(page, 0))
return 0;
- write_lock_irq(&mapping->tree_lock);
- if (PageDirty(page)) {
- write_unlock_irq(&mapping->tree_lock);
- return 0;
+ clear_page_mlock(page);
+ 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_CACHE_SHIFT,
+ PAGE_CACHE_SIZE, 0);
}
+ return truncate_complete_page(mapping, page);
+}
- BUG_ON(PagePrivate(page));
- __remove_from_page_cache(page);
- write_unlock_irq(&mapping->tree_lock);
- ClearPageUptodate(page);
- page_cache_release(page); /* pagecache ref */
- return 1;
+/*
+ * 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 - truncate *all* the pages from an offset
+ * truncate_inode_pages - 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
*
- * Truncate the page cache at a set offset, removing the pages that are beyond
- * that offset (and zeroing out partial pages).
+ * Truncate the page cache, removing the pages that are between
+ * specified offsets (and zeroing out partial page
+ * (if lstart 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
* 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.
- *
- * Called under (and serialised by) inode->i_sem.
*/
-void truncate_inode_pages(struct address_space *mapping, loff_t lstart)
+void truncate_inode_pages_range(struct address_space *mapping,
+ loff_t lstart, loff_t lend)
{
const pgoff_t start = (lstart + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT;
+ pgoff_t end;
const unsigned partial = lstart & (PAGE_CACHE_SIZE - 1);
struct pagevec pvec;
pgoff_t next;
if (mapping->nrpages == 0)
return;
+ BUG_ON((lend & (PAGE_CACHE_SIZE - 1)) != (PAGE_CACHE_SIZE - 1));
+ end = (lend >> PAGE_CACHE_SHIFT);
+
pagevec_init(&pvec, 0);
next = start;
- while (pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
+ while (next <= end &&
+ pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
for (i = 0; i < pagevec_count(&pvec); i++) {
struct page *page = pvec.pages[i];
pgoff_t page_index = page->index;
+ if (page_index > end) {
+ next = page_index;
+ break;
+ }
+
if (page_index > next)
next = page_index;
next++;
- if (TestSetPageLocked(page))
+ if (!trylock_page(page))
continue;
if (PageWriteback(page)) {
unlock_page(page);
continue;
}
- truncate_complete_page(mapping, page);
+ truncate_inode_page(mapping, page);
unlock_page(page);
}
pagevec_release(&pvec);
next = start;
continue;
}
+ if (pvec.pages[0]->index > end) {
+ pagevec_release(&pvec);
+ break;
+ }
+ mem_cgroup_uncharge_start();
for (i = 0; i < pagevec_count(&pvec); i++) {
struct page *page = pvec.pages[i];
+ if (page->index > end)
+ break;
lock_page(page);
wait_on_page_writeback(page);
+ truncate_inode_page(mapping, page);
if (page->index > next)
next = page->index;
next++;
- truncate_complete_page(mapping, page);
unlock_page(page);
}
pagevec_release(&pvec);
+ mem_cgroup_uncharge_end();
}
}
+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.
+ */
+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);
/**
* pagetables.
*/
unsigned long invalidate_mapping_pages(struct address_space *mapping,
- pgoff_t start, pgoff_t end)
+ pgoff_t start, pgoff_t end)
{
struct pagevec pvec;
pgoff_t next = start;
pagevec_init(&pvec, 0);
while (next <= end &&
pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
+ mem_cgroup_uncharge_start();
for (i = 0; i < pagevec_count(&pvec); i++) {
struct page *page = pvec.pages[i];
+ pgoff_t index;
+ int lock_failed;
- if (TestSetPageLocked(page)) {
- next++;
- continue;
- }
- if (page->index > next)
- next = page->index;
+ lock_failed = !trylock_page(page);
+
+ /*
+ * We really shouldn't be looking at the ->index of an
+ * unlocked page. But we're not allowed to lock these
+ * pages. So we rely upon nobody altering the ->index
+ * of this (pinned-by-us) page.
+ */
+ index = page->index;
+ if (index > next)
+ next = index;
next++;
- if (PageDirty(page) || PageWriteback(page))
- goto unlock;
- if (page_mapped(page))
- goto unlock;
- ret += invalidate_complete_page(mapping, page);
-unlock:
+ if (lock_failed)
+ continue;
+
+ ret += invalidate_inode_page(page);
+
unlock_page(page);
if (next > end)
break;
}
pagevec_release(&pvec);
+ mem_cgroup_uncharge_end();
cond_resched();
}
return ret;
}
+EXPORT_SYMBOL(invalidate_mapping_pages);
-unsigned long invalidate_inode_pages(struct address_space *mapping)
+/*
+ * 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)
{
- return invalidate_mapping_pages(mapping, 0, ~0UL);
+ if (page->mapping != mapping)
+ return 0;
+
+ if (page_has_private(page) && !try_to_release_page(page, GFP_KERNEL))
+ return 0;
+
+ spin_lock_irq(&mapping->tree_lock);
+ if (PageDirty(page))
+ goto failed;
+
+ clear_page_mlock(page);
+ BUG_ON(page_has_private(page));
+ __remove_from_page_cache(page);
+ spin_unlock_irq(&mapping->tree_lock);
+ mem_cgroup_uncharge_cache_page(page);
+ page_cache_release(page); /* pagecache ref */
+ return 1;
+failed:
+ spin_unlock_irq(&mapping->tree_lock);
+ return 0;
}
-EXPORT_SYMBOL(invalidate_inode_pages);
+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
* Any pages which are found to be mapped into pagetables are unmapped prior to
* invalidation.
*
- * Returns -EIO if any pages could not be invalidated.
+ * 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 next;
int i;
int ret = 0;
+ int ret2 = 0;
int did_range_unmap = 0;
int wrapped = 0;
pagevec_init(&pvec, 0);
next = start;
- while (next <= end && !ret && !wrapped &&
+ while (next <= end && !wrapped &&
pagevec_lookup(&pvec, mapping, next,
min(end - next, (pgoff_t)PAGEVEC_SIZE - 1) + 1)) {
- for (i = 0; !ret && i < pagevec_count(&pvec); i++) {
+ mem_cgroup_uncharge_start();
+ for (i = 0; i < pagevec_count(&pvec); i++) {
struct page *page = pvec.pages[i];
pgoff_t page_index;
- int was_dirty;
lock_page(page);
if (page->mapping != mapping) {
break;
}
wait_on_page_writeback(page);
- while (page_mapped(page)) {
+ if (page_mapped(page)) {
if (!did_range_unmap) {
/*
* Zap the rest of the file in one hit.
*/
unmap_mapping_range(mapping,
- page_index << PAGE_CACHE_SHIFT,
- (end - page_index + 1)
+ (loff_t)page_index<<PAGE_CACHE_SHIFT,
+ (loff_t)(end - page_index + 1)
<< PAGE_CACHE_SHIFT,
0);
did_range_unmap = 1;
* Just zap this page
*/
unmap_mapping_range(mapping,
- page_index << PAGE_CACHE_SHIFT,
+ (loff_t)page_index<<PAGE_CACHE_SHIFT,
PAGE_CACHE_SIZE, 0);
}
}
- was_dirty = test_clear_page_dirty(page);
- if (!invalidate_complete_page(mapping, page)) {
- if (was_dirty)
- set_page_dirty(page);
- ret = -EIO;
+ 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_release(&pvec);
+ mem_cgroup_uncharge_end();
cond_resched();
}
return ret;
* Any pages which are found to be mapped into pagetables are unmapped prior to
* invalidation.
*
- * Returns -EIO if any pages could not be invalidated.
+ * 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
+ * @old: old file offset
+ * @new: new file offset
+ *
+ * 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 old, loff_t new)
+{
+ struct address_space *mapping = inode->i_mapping;
+
+ /*
+ * 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, new + PAGE_SIZE - 1, 0, 1);
+ truncate_inode_pages(mapping, new);
+ unmap_mapping_range(mapping, new + PAGE_SIZE - 1, 0, 1);
+}
+EXPORT_SYMBOL(truncate_pagecache);
+
+/**
+ * vmtruncate - unmap mappings "freed" by truncate() syscall
+ * @inode: inode of the file used
+ * @offset: file offset to start truncating
+ *
+ * NOTE! We have to be ready to update the memory sharing
+ * between the file and the memory map for a potential last
+ * incomplete page. Ugly, but necessary.
+ */
+int vmtruncate(struct inode *inode, loff_t offset)
+{
+ loff_t oldsize;
+ int error;
+
+ error = inode_newsize_ok(inode, offset);
+ if (error)
+ return error;
+ oldsize = inode->i_size;
+ i_size_write(inode, offset);
+ truncate_pagecache(inode, oldsize, offset);
+ if (inode->i_op->truncate)
+ inode->i_op->truncate(inode);
+
+ return error;
+}
+EXPORT_SYMBOL(vmtruncate);
Code Review / linux-2.6.git / blobdiff