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9361401eb7
Make it possible to disable the block layer. Not all embedded devices require it, some can make do with just JFFS2, NFS, ramfs, etc - none of which require the block layer to be present. This patch does the following: (*) Introduces CONFIG_BLOCK to disable the block layer, buffering and blockdev support. (*) Adds dependencies on CONFIG_BLOCK to any configuration item that controls an item that uses the block layer. This includes: (*) Block I/O tracing. (*) Disk partition code. (*) All filesystems that are block based, eg: Ext3, ReiserFS, ISOFS. (*) The SCSI layer. As far as I can tell, even SCSI chardevs use the block layer to do scheduling. Some drivers that use SCSI facilities - such as USB storage - end up disabled indirectly from this. (*) Various block-based device drivers, such as IDE and the old CDROM drivers. (*) MTD blockdev handling and FTL. (*) JFFS - which uses set_bdev_super(), something it could avoid doing by taking a leaf out of JFFS2's book. (*) Makes most of the contents of linux/blkdev.h, linux/buffer_head.h and linux/elevator.h contingent on CONFIG_BLOCK being set. sector_div() is, however, still used in places, and so is still available. (*) Also made contingent are the contents of linux/mpage.h, linux/genhd.h and parts of linux/fs.h. (*) Makes a number of files in fs/ contingent on CONFIG_BLOCK. (*) Makes mm/bounce.c (bounce buffering) contingent on CONFIG_BLOCK. (*) set_page_dirty() doesn't call __set_page_dirty_buffers() if CONFIG_BLOCK is not enabled. (*) fs/no-block.c is created to hold out-of-line stubs and things that are required when CONFIG_BLOCK is not set: (*) Default blockdev file operations (to give error ENODEV on opening). (*) Makes some /proc changes: (*) /proc/devices does not list any blockdevs. (*) /proc/diskstats and /proc/partitions are contingent on CONFIG_BLOCK. (*) Makes some compat ioctl handling contingent on CONFIG_BLOCK. (*) If CONFIG_BLOCK is not defined, makes sys_quotactl() return -ENODEV if given command other than Q_SYNC or if a special device is specified. (*) In init/do_mounts.c, no reference is made to the blockdev routines if CONFIG_BLOCK is not defined. This does not prohibit NFS roots or JFFS2. (*) The bdflush, ioprio_set and ioprio_get syscalls can now be absent (return error ENOSYS by way of cond_syscall if so). (*) The seclvl_bd_claim() and seclvl_bd_release() security calls do nothing if CONFIG_BLOCK is not set, since they can't then happen. Signed-Off-By: David Howells <dhowells@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
387 lines
10 KiB
C
387 lines
10 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 akpm@zip.com.au
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* Initial version.
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*/
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#include <linux/kernel.h>
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#include <linux/mm.h>
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#include <linux/swap.h>
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#include <linux/module.h>
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#include <linux/pagemap.h>
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#include <linux/pagevec.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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/**
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* do_invalidatepage - invalidate part of 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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memclear_highpage_flush(page, partial, PAGE_CACHE_SIZE-partial);
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if (PagePrivate(page))
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do_invalidatepage(page, partial);
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}
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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 anonymous. 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_nopage().
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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_inode_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 void
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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;
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if (PagePrivate(page))
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do_invalidatepage(page, 0);
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clear_page_dirty(page);
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ClearPageUptodate(page);
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ClearPageMappedToDisk(page);
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remove_from_page_cache(page);
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page_cache_release(page); /* pagecache ref */
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}
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/*
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* This is for invalidate_inode_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 (PagePrivate(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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ClearPageUptodate(page);
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return ret;
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}
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/**
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* truncate_inode_pages - truncate range of pages specified by start and
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* 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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* When looking at page->index outside the page lock we need to be careful to
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* copy it into a local to avoid races (it could change at any time).
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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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pgoff_t end;
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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 next;
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int i;
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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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next = start;
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while (next <= end &&
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pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
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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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pgoff_t page_index = page->index;
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if (page_index > end) {
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next = page_index;
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break;
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}
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if (page_index > next)
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next = page_index;
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next++;
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if (TestSetPageLocked(page))
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continue;
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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_complete_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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cond_resched();
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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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next = start;
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for ( ; ; ) {
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cond_resched();
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if (!pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
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if (next == start)
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break;
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next = start;
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continue;
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}
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if (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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for (i = 0; i < pagevec_count(&pvec); i++) {
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struct page *page = pvec.pages[i];
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if (page->index > end)
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break;
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lock_page(page);
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wait_on_page_writeback(page);
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if (page->index > next)
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next = page->index;
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next++;
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truncate_complete_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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}
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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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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 next = start;
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unsigned long ret = 0;
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int i;
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pagevec_init(&pvec, 0);
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while (next <= end &&
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pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
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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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pgoff_t index;
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int lock_failed;
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lock_failed = TestSetPageLocked(page);
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/*
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* We really shouldn't be looking at the ->index of an
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* unlocked page. But we're not allowed to lock these
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* pages. So we rely upon nobody altering the ->index
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* of this (pinned-by-us) page.
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*/
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index = page->index;
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if (index > next)
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next = index;
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next++;
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if (lock_failed)
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continue;
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if (PageDirty(page) || PageWriteback(page))
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goto unlock;
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if (page_mapped(page))
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goto unlock;
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ret += invalidate_complete_page(mapping, page);
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unlock:
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unlock_page(page);
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if (next > end)
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break;
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}
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pagevec_release(&pvec);
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}
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return ret;
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}
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unsigned long invalidate_inode_pages(struct address_space *mapping)
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{
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return invalidate_mapping_pages(mapping, 0, ~0UL);
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}
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EXPORT_SYMBOL(invalidate_inode_pages);
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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 -EIO 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 next;
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int i;
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int ret = 0;
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int did_range_unmap = 0;
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int wrapped = 0;
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pagevec_init(&pvec, 0);
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next = start;
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while (next <= end && !ret && !wrapped &&
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pagevec_lookup(&pvec, mapping, next,
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min(end - next, (pgoff_t)PAGEVEC_SIZE - 1) + 1)) {
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for (i = 0; !ret && i < pagevec_count(&pvec); i++) {
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struct page *page = pvec.pages[i];
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pgoff_t page_index;
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int was_dirty;
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lock_page(page);
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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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page_index = page->index;
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next = page_index + 1;
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if (next == 0)
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wrapped = 1;
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if (page_index > end) {
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unlock_page(page);
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break;
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}
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wait_on_page_writeback(page);
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while (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)page_index<<PAGE_CACHE_SHIFT,
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(loff_t)(end - page_index + 1)
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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)page_index<<PAGE_CACHE_SHIFT,
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PAGE_CACHE_SIZE, 0);
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}
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}
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was_dirty = test_clear_page_dirty(page);
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if (!invalidate_complete_page(mapping, page)) {
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if (was_dirty)
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set_page_dirty(page);
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ret = -EIO;
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}
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unlock_page(page);
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}
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pagevec_release(&pvec);
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cond_resched();
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}
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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
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* invalidation.
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*
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* Returns -EIO if any pages could not be invalidated.
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*/
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int invalidate_inode_pages2(struct address_space *mapping)
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{
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return invalidate_inode_pages2_range(mapping, 0, -1);
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}
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EXPORT_SYMBOL_GPL(invalidate_inode_pages2);
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