X-Git-Url: http://ftp.safe.ca/?a=blobdiff_plain;f=mm%2Ftruncate.c;h=937571b8b23370afdcb607ae27a3a897464e46bb;hb=3d00d4ff11686895925f46265f4a78dc78196c2e;hp=9173ab500604d904747f6f2681b9eb1305de7b42;hpb=479ef592f3664dd629417098c8599261c0f689ab;p=safe%2Fjmp%2Flinux-2.6 diff --git a/mm/truncate.c b/mm/truncate.c index 9173ab5..937571b 100644 --- a/mm/truncate.c +++ b/mm/truncate.c @@ -3,91 +3,194 @@ * * Copyright (C) 2002, Linus Torvalds * - * 10Sep2002 akpm@zip.com.au + * 10Sep2002 Andrew Morton * Initial version. */ #include +#include +#include #include +#include #include #include +#include #include +#include #include /* 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 @@ -101,12 +204,12 @@ invalidate_complete_page(struct address_space *mapping, struct page *page) * 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; @@ -115,23 +218,32 @@ void truncate_inode_pages(struct address_space *mapping, loff_t lstart) 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); @@ -157,21 +269,41 @@ void truncate_inode_pages(struct address_space *mapping, loff_t lstart) 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); /** @@ -188,7 +320,7 @@ 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; @@ -198,38 +330,81 @@ unsigned long invalidate_mapping_pages(struct address_space *mapping, 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 @@ -240,7 +415,7 @@ EXPORT_SYMBOL(invalidate_inode_pages); * 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) @@ -249,18 +424,19 @@ int invalidate_inode_pages2_range(struct address_space *mapping, 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) { @@ -276,7 +452,7 @@ int invalidate_inode_pages2_range(struct address_space *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. @@ -296,15 +472,18 @@ int invalidate_inode_pages2_range(struct address_space *mapping, 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; @@ -318,10 +497,72 @@ EXPORT_SYMBOL_GPL(invalidate_inode_pages2_range); * 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. + * + * This function is deprecated and simple_setsize or truncate_pagecache + * should be used instead. + */ +int vmtruncate(struct inode *inode, loff_t offset) +{ + int error; + + error = simple_setsize(inode, offset); + if (error) + return error; + + if (inode->i_op->truncate) + inode->i_op->truncate(inode); + + return error; +} +EXPORT_SYMBOL(vmtruncate);