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![Marco Stornelli](/assets/img/avatar_default.png)
Removed vmtruncate Signed-off-by: Marco Stornelli <marco.stornelli@gmail.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
617 lines
18 KiB
C
617 lines
18 KiB
C
/*
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* mm/truncate.c - code for taking down pages from address_spaces
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*
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* Copyright (C) 2002, Linus Torvalds
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*
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* 10Sep2002 Andrew Morton
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* Initial version.
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*/
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#include <linux/kernel.h>
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#include <linux/backing-dev.h>
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#include <linux/gfp.h>
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#include <linux/mm.h>
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#include <linux/swap.h>
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#include <linux/export.h>
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#include <linux/pagemap.h>
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#include <linux/highmem.h>
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#include <linux/pagevec.h>
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#include <linux/task_io_accounting_ops.h>
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#include <linux/buffer_head.h> /* grr. try_to_release_page,
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do_invalidatepage */
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#include <linux/cleancache.h>
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#include "internal.h"
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/**
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* do_invalidatepage - invalidate part or all of a page
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* @page: the page which is affected
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* @offset: the index of the truncation point
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*
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* do_invalidatepage() is called when all or part of the page has become
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* invalidated by a truncate operation.
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*
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* do_invalidatepage() does not have to release all buffers, but it must
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* ensure that no dirty buffer is left outside @offset and that no I/O
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* is underway against any of the blocks which are outside the truncation
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* point. Because the caller is about to free (and possibly reuse) those
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* blocks on-disk.
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*/
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void do_invalidatepage(struct page *page, unsigned long offset)
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{
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void (*invalidatepage)(struct page *, unsigned long);
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invalidatepage = page->mapping->a_ops->invalidatepage;
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#ifdef CONFIG_BLOCK
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if (!invalidatepage)
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invalidatepage = block_invalidatepage;
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#endif
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if (invalidatepage)
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(*invalidatepage)(page, offset);
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}
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static inline void truncate_partial_page(struct page *page, unsigned partial)
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{
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zero_user_segment(page, partial, PAGE_CACHE_SIZE);
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cleancache_invalidate_page(page->mapping, page);
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if (page_has_private(page))
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do_invalidatepage(page, partial);
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}
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/*
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* This cancels just the dirty bit on the kernel page itself, it
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* does NOT actually remove dirty bits on any mmap's that may be
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* around. It also leaves the page tagged dirty, so any sync
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* activity will still find it on the dirty lists, and in particular,
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* clear_page_dirty_for_io() will still look at the dirty bits in
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* the VM.
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*
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* Doing this should *normally* only ever be done when a page
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* is truncated, and is not actually mapped anywhere at all. However,
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* fs/buffer.c does this when it notices that somebody has cleaned
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* out all the buffers on a page without actually doing it through
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* the VM. Can you say "ext3 is horribly ugly"? Tought you could.
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*/
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void cancel_dirty_page(struct page *page, unsigned int account_size)
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{
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if (TestClearPageDirty(page)) {
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struct address_space *mapping = page->mapping;
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if (mapping && mapping_cap_account_dirty(mapping)) {
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dec_zone_page_state(page, NR_FILE_DIRTY);
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dec_bdi_stat(mapping->backing_dev_info,
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BDI_RECLAIMABLE);
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if (account_size)
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task_io_account_cancelled_write(account_size);
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}
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}
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}
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EXPORT_SYMBOL(cancel_dirty_page);
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/*
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* If truncate cannot remove the fs-private metadata from the page, the page
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* becomes orphaned. It will be left on the LRU and may even be mapped into
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* user pagetables if we're racing with filemap_fault().
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*
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* We need to bale out if page->mapping is no longer equal to the original
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* mapping. This happens a) when the VM reclaimed the page while we waited on
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* its lock, b) when a concurrent invalidate_mapping_pages got there first and
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* c) when tmpfs swizzles a page between a tmpfs inode and swapper_space.
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*/
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static int
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truncate_complete_page(struct address_space *mapping, struct page *page)
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{
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if (page->mapping != mapping)
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return -EIO;
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if (page_has_private(page))
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do_invalidatepage(page, 0);
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cancel_dirty_page(page, PAGE_CACHE_SIZE);
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ClearPageMappedToDisk(page);
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delete_from_page_cache(page);
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return 0;
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}
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/*
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* This is for invalidate_mapping_pages(). That function can be called at
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* any time, and is not supposed to throw away dirty pages. But pages can
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* be marked dirty at any time too, so use remove_mapping which safely
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* discards clean, unused pages.
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*
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* Returns non-zero if the page was successfully invalidated.
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*/
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static int
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invalidate_complete_page(struct address_space *mapping, struct page *page)
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{
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int ret;
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if (page->mapping != mapping)
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return 0;
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if (page_has_private(page) && !try_to_release_page(page, 0))
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return 0;
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ret = remove_mapping(mapping, page);
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return ret;
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}
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int truncate_inode_page(struct address_space *mapping, struct page *page)
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{
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if (page_mapped(page)) {
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unmap_mapping_range(mapping,
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(loff_t)page->index << PAGE_CACHE_SHIFT,
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PAGE_CACHE_SIZE, 0);
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}
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return truncate_complete_page(mapping, page);
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}
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/*
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* Used to get rid of pages on hardware memory corruption.
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*/
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int generic_error_remove_page(struct address_space *mapping, struct page *page)
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{
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if (!mapping)
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return -EINVAL;
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/*
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* Only punch for normal data pages for now.
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* Handling other types like directories would need more auditing.
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*/
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if (!S_ISREG(mapping->host->i_mode))
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return -EIO;
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return truncate_inode_page(mapping, page);
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}
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EXPORT_SYMBOL(generic_error_remove_page);
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/*
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* Safely invalidate one page from its pagecache mapping.
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* It only drops clean, unused pages. The page must be locked.
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*
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* Returns 1 if the page is successfully invalidated, otherwise 0.
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*/
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int invalidate_inode_page(struct page *page)
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{
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struct address_space *mapping = page_mapping(page);
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if (!mapping)
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return 0;
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if (PageDirty(page) || PageWriteback(page))
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return 0;
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if (page_mapped(page))
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return 0;
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return invalidate_complete_page(mapping, page);
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}
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/**
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* truncate_inode_pages_range - truncate range of pages specified by start & end byte offsets
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* @mapping: mapping to truncate
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* @lstart: offset from which to truncate
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* @lend: offset to which to truncate
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*
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* Truncate the page cache, removing the pages that are between
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* specified offsets (and zeroing out partial page
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* (if lstart is not page aligned)).
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*
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* Truncate takes two passes - the first pass is nonblocking. It will not
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* block on page locks and it will not block on writeback. The second pass
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* will wait. This is to prevent as much IO as possible in the affected region.
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* The first pass will remove most pages, so the search cost of the second pass
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* is low.
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*
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* We pass down the cache-hot hint to the page freeing code. Even if the
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* mapping is large, it is probably the case that the final pages are the most
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* recently touched, and freeing happens in ascending file offset order.
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*/
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void truncate_inode_pages_range(struct address_space *mapping,
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loff_t lstart, loff_t lend)
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{
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const pgoff_t start = (lstart + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT;
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const unsigned partial = lstart & (PAGE_CACHE_SIZE - 1);
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struct pagevec pvec;
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pgoff_t index;
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pgoff_t end;
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int i;
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cleancache_invalidate_inode(mapping);
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if (mapping->nrpages == 0)
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return;
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BUG_ON((lend & (PAGE_CACHE_SIZE - 1)) != (PAGE_CACHE_SIZE - 1));
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end = (lend >> PAGE_CACHE_SHIFT);
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pagevec_init(&pvec, 0);
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index = start;
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while (index <= end && pagevec_lookup(&pvec, mapping, index,
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min(end - index, (pgoff_t)PAGEVEC_SIZE - 1) + 1)) {
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mem_cgroup_uncharge_start();
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for (i = 0; i < pagevec_count(&pvec); i++) {
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struct page *page = pvec.pages[i];
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/* We rely upon deletion not changing page->index */
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index = page->index;
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if (index > end)
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break;
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if (!trylock_page(page))
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continue;
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WARN_ON(page->index != index);
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if (PageWriteback(page)) {
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unlock_page(page);
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continue;
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}
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truncate_inode_page(mapping, page);
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unlock_page(page);
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}
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pagevec_release(&pvec);
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mem_cgroup_uncharge_end();
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cond_resched();
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index++;
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}
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if (partial) {
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struct page *page = find_lock_page(mapping, start - 1);
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if (page) {
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wait_on_page_writeback(page);
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truncate_partial_page(page, partial);
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unlock_page(page);
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page_cache_release(page);
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}
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}
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index = start;
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for ( ; ; ) {
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cond_resched();
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if (!pagevec_lookup(&pvec, mapping, index,
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min(end - index, (pgoff_t)PAGEVEC_SIZE - 1) + 1)) {
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if (index == start)
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break;
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index = start;
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continue;
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}
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if (index == start && pvec.pages[0]->index > end) {
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pagevec_release(&pvec);
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break;
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}
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mem_cgroup_uncharge_start();
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for (i = 0; i < pagevec_count(&pvec); i++) {
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struct page *page = pvec.pages[i];
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/* We rely upon deletion not changing page->index */
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index = page->index;
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if (index > end)
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break;
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lock_page(page);
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WARN_ON(page->index != index);
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wait_on_page_writeback(page);
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truncate_inode_page(mapping, page);
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unlock_page(page);
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}
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pagevec_release(&pvec);
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mem_cgroup_uncharge_end();
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index++;
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}
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cleancache_invalidate_inode(mapping);
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}
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EXPORT_SYMBOL(truncate_inode_pages_range);
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/**
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* truncate_inode_pages - truncate *all* the pages from an offset
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* @mapping: mapping to truncate
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* @lstart: offset from which to truncate
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*
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* Called under (and serialised by) inode->i_mutex.
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*
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* Note: When this function returns, there can be a page in the process of
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* deletion (inside __delete_from_page_cache()) in the specified range. Thus
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* mapping->nrpages can be non-zero when this function returns even after
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* truncation of the whole mapping.
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*/
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void truncate_inode_pages(struct address_space *mapping, loff_t lstart)
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{
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truncate_inode_pages_range(mapping, lstart, (loff_t)-1);
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}
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EXPORT_SYMBOL(truncate_inode_pages);
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/**
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* invalidate_mapping_pages - Invalidate all the unlocked pages of one inode
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* @mapping: the address_space which holds the pages to invalidate
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* @start: the offset 'from' which to invalidate
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* @end: the offset 'to' which to invalidate (inclusive)
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*
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* This function only removes the unlocked pages, if you want to
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* remove all the pages of one inode, you must call truncate_inode_pages.
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*
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* invalidate_mapping_pages() will not block on IO activity. It will not
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* invalidate pages which are dirty, locked, under writeback or mapped into
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* pagetables.
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*/
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unsigned long invalidate_mapping_pages(struct address_space *mapping,
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pgoff_t start, pgoff_t end)
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{
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struct pagevec pvec;
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pgoff_t index = start;
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unsigned long ret;
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unsigned long count = 0;
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int i;
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/*
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* Note: this function may get called on a shmem/tmpfs mapping:
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* pagevec_lookup() might then return 0 prematurely (because it
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* got a gangful of swap entries); but it's hardly worth worrying
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* about - it can rarely have anything to free from such a mapping
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* (most pages are dirty), and already skips over any difficulties.
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*/
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pagevec_init(&pvec, 0);
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while (index <= end && pagevec_lookup(&pvec, mapping, index,
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min(end - index, (pgoff_t)PAGEVEC_SIZE - 1) + 1)) {
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mem_cgroup_uncharge_start();
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for (i = 0; i < pagevec_count(&pvec); i++) {
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struct page *page = pvec.pages[i];
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/* We rely upon deletion not changing page->index */
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index = page->index;
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if (index > end)
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break;
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if (!trylock_page(page))
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continue;
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WARN_ON(page->index != index);
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ret = invalidate_inode_page(page);
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unlock_page(page);
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/*
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* Invalidation is a hint that the page is no longer
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* of interest and try to speed up its reclaim.
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*/
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if (!ret)
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deactivate_page(page);
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count += ret;
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}
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pagevec_release(&pvec);
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mem_cgroup_uncharge_end();
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cond_resched();
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index++;
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}
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return count;
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}
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EXPORT_SYMBOL(invalidate_mapping_pages);
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/*
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* This is like invalidate_complete_page(), except it ignores the page's
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* refcount. We do this because invalidate_inode_pages2() needs stronger
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* invalidation guarantees, and cannot afford to leave pages behind because
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* shrink_page_list() has a temp ref on them, or because they're transiently
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* sitting in the lru_cache_add() pagevecs.
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*/
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static int
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invalidate_complete_page2(struct address_space *mapping, struct page *page)
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{
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if (page->mapping != mapping)
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return 0;
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if (page_has_private(page) && !try_to_release_page(page, GFP_KERNEL))
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return 0;
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spin_lock_irq(&mapping->tree_lock);
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if (PageDirty(page))
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goto failed;
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BUG_ON(page_has_private(page));
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__delete_from_page_cache(page);
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spin_unlock_irq(&mapping->tree_lock);
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mem_cgroup_uncharge_cache_page(page);
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if (mapping->a_ops->freepage)
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mapping->a_ops->freepage(page);
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page_cache_release(page); /* pagecache ref */
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return 1;
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failed:
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spin_unlock_irq(&mapping->tree_lock);
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return 0;
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}
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static int do_launder_page(struct address_space *mapping, struct page *page)
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{
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if (!PageDirty(page))
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return 0;
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if (page->mapping != mapping || mapping->a_ops->launder_page == NULL)
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return 0;
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return mapping->a_ops->launder_page(page);
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}
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/**
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* invalidate_inode_pages2_range - remove range of pages from an address_space
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* @mapping: the address_space
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* @start: the page offset 'from' which to invalidate
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* @end: the page offset 'to' which to invalidate (inclusive)
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*
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* Any pages which are found to be mapped into pagetables are unmapped prior to
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* invalidation.
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*
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* Returns -EBUSY if any pages could not be invalidated.
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*/
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int invalidate_inode_pages2_range(struct address_space *mapping,
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pgoff_t start, pgoff_t end)
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{
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struct pagevec pvec;
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pgoff_t index;
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int i;
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int ret = 0;
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int ret2 = 0;
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int did_range_unmap = 0;
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cleancache_invalidate_inode(mapping);
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pagevec_init(&pvec, 0);
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index = start;
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while (index <= end && pagevec_lookup(&pvec, mapping, index,
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min(end - index, (pgoff_t)PAGEVEC_SIZE - 1) + 1)) {
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mem_cgroup_uncharge_start();
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for (i = 0; i < pagevec_count(&pvec); i++) {
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struct page *page = pvec.pages[i];
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/* We rely upon deletion not changing page->index */
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index = page->index;
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if (index > end)
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break;
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lock_page(page);
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WARN_ON(page->index != index);
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if (page->mapping != mapping) {
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unlock_page(page);
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continue;
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}
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wait_on_page_writeback(page);
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if (page_mapped(page)) {
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if (!did_range_unmap) {
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/*
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* Zap the rest of the file in one hit.
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*/
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unmap_mapping_range(mapping,
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(loff_t)index << PAGE_CACHE_SHIFT,
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(loff_t)(1 + end - index)
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<< PAGE_CACHE_SHIFT,
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0);
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did_range_unmap = 1;
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} else {
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/*
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* Just zap this page
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*/
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unmap_mapping_range(mapping,
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(loff_t)index << PAGE_CACHE_SHIFT,
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PAGE_CACHE_SIZE, 0);
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}
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}
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BUG_ON(page_mapped(page));
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ret2 = do_launder_page(mapping, page);
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if (ret2 == 0) {
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if (!invalidate_complete_page2(mapping, page))
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ret2 = -EBUSY;
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}
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if (ret2 < 0)
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ret = ret2;
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unlock_page(page);
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}
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pagevec_release(&pvec);
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mem_cgroup_uncharge_end();
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cond_resched();
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index++;
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}
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cleancache_invalidate_inode(mapping);
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return ret;
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}
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EXPORT_SYMBOL_GPL(invalidate_inode_pages2_range);
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/**
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* invalidate_inode_pages2 - remove all pages from an address_space
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* @mapping: the address_space
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*
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* 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
|
|
* @oldsize: old file size
|
|
* @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 oldsize, 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 inode_mutex held and before all filesystem specific
|
|
* block truncation has been performed.
|
|
*/
|
|
void truncate_setsize(struct inode *inode, loff_t newsize)
|
|
{
|
|
loff_t oldsize;
|
|
|
|
oldsize = inode->i_size;
|
|
i_size_write(inode, newsize);
|
|
|
|
truncate_pagecache(inode, oldsize, newsize);
|
|
}
|
|
EXPORT_SYMBOL(truncate_setsize);
|
|
|
|
/**
|
|
* 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; and truncate_inode_pages_range
|
|
* currently BUGs if lend is not pagealigned-1 (it handles partial
|
|
* page at start of hole, but not partial page at end of hole). Note
|
|
* unmap_mapping_range allows holelen 0 for all, and we allow lend -1.
|
|
*/
|
|
|
|
/*
|
|
* 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);
|