consolidate generic_writepages and mpage_writepages
Clean up massive code duplication between mpage_writepages() and generic_writepages(). The new generic function, write_cache_pages() takes a function pointer argument, which will be called for each page to be written. Maybe cifs_writepages() too can use this infrastructure, but I'm not touching that with a ten-foot pole. The upcoming page writeback support in fuse will also want this. Signed-off-by: Miklos Szeredi <mszeredi@suse.cz> Acked-by: Christoph Hellwig <hch@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Miklos Szeredi
Linus Torvalds
Родитель
e10cc1df1d
Коммит
0ea9718016
172
fs/mpage.c
172
fs/mpage.c
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@ -454,11 +454,18 @@ EXPORT_SYMBOL(mpage_readpage);
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* written, so it can intelligently allocate a suitably-sized BIO. For now,
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* just allocate full-size (16-page) BIOs.
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*/
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static struct bio *
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__mpage_writepage(struct bio *bio, struct page *page, get_block_t get_block,
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sector_t *last_block_in_bio, int *ret, struct writeback_control *wbc,
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writepage_t writepage_fn)
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struct mpage_data {
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struct bio *bio;
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sector_t last_block_in_bio;
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get_block_t *get_block;
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unsigned use_writepage;
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};
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static int __mpage_writepage(struct page *page, struct writeback_control *wbc,
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void *data)
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{
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struct mpage_data *mpd = data;
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struct bio *bio = mpd->bio;
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struct address_space *mapping = page->mapping;
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struct inode *inode = page->mapping->host;
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const unsigned blkbits = inode->i_blkbits;
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@ -476,6 +483,7 @@ __mpage_writepage(struct bio *bio, struct page *page, get_block_t get_block,
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int length;
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struct buffer_head map_bh;
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loff_t i_size = i_size_read(inode);
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int ret = 0;
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if (page_has_buffers(page)) {
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struct buffer_head *head = page_buffers(page);
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@ -538,7 +546,7 @@ __mpage_writepage(struct bio *bio, struct page *page, get_block_t get_block,
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map_bh.b_state = 0;
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map_bh.b_size = 1 << blkbits;
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if (get_block(inode, block_in_file, &map_bh, 1))
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if (mpd->get_block(inode, block_in_file, &map_bh, 1))
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goto confused;
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if (buffer_new(&map_bh))
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unmap_underlying_metadata(map_bh.b_bdev,
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@ -584,7 +592,7 @@ page_is_mapped:
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/*
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* This page will go to BIO. Do we need to send this BIO off first?
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*/
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if (bio && *last_block_in_bio != blocks[0] - 1)
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if (bio && mpd->last_block_in_bio != blocks[0] - 1)
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bio = mpage_bio_submit(WRITE, bio);
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alloc_new:
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@ -641,7 +649,7 @@ alloc_new:
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boundary_block, 1 << blkbits);
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}
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} else {
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*last_block_in_bio = blocks[blocks_per_page - 1];
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mpd->last_block_in_bio = blocks[blocks_per_page - 1];
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}
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goto out;
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@ -649,18 +657,19 @@ confused:
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if (bio)
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bio = mpage_bio_submit(WRITE, bio);
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if (writepage_fn) {
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*ret = (*writepage_fn)(page, wbc);
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if (mpd->use_writepage) {
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ret = mapping->a_ops->writepage(page, wbc);
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} else {
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*ret = -EAGAIN;
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ret = -EAGAIN;
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goto out;
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}
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/*
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* The caller has a ref on the inode, so *mapping is stable
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*/
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mapping_set_error(mapping, *ret);
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mapping_set_error(mapping, ret);
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out:
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return bio;
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mpd->bio = bio;
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return ret;
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}
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/**
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@ -683,120 +692,27 @@ out:
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* the call was made get new I/O started against them. If wbc->sync_mode is
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* WB_SYNC_ALL then we were called for data integrity and we must wait for
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* existing IO to complete.
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*
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* If you fix this you should check generic_writepages() also!
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*/
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int
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mpage_writepages(struct address_space *mapping,
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struct writeback_control *wbc, get_block_t get_block)
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{
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struct backing_dev_info *bdi = mapping->backing_dev_info;
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struct bio *bio = NULL;
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sector_t last_block_in_bio = 0;
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int ret = 0;
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int done = 0;
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int (*writepage)(struct page *page, struct writeback_control *wbc);
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struct pagevec pvec;
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int nr_pages;
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pgoff_t index;
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pgoff_t end; /* Inclusive */
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int scanned = 0;
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int range_whole = 0;
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int ret;
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if (wbc->nonblocking && bdi_write_congested(bdi)) {
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wbc->encountered_congestion = 1;
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return 0;
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if (!get_block)
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ret = generic_writepages(mapping, wbc);
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else {
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struct mpage_data mpd = {
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.bio = NULL,
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.last_block_in_bio = 0,
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.get_block = get_block,
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.use_writepage = 1,
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};
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ret = write_cache_pages(mapping, wbc, __mpage_writepage, &mpd);
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if (mpd.bio)
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mpage_bio_submit(WRITE, mpd.bio);
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}
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writepage = NULL;
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if (get_block == NULL)
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writepage = mapping->a_ops->writepage;
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pagevec_init(&pvec, 0);
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if (wbc->range_cyclic) {
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index = mapping->writeback_index; /* Start from prev offset */
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end = -1;
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} else {
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index = wbc->range_start >> PAGE_CACHE_SHIFT;
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end = wbc->range_end >> PAGE_CACHE_SHIFT;
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if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
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range_whole = 1;
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scanned = 1;
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}
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retry:
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while (!done && (index <= end) &&
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(nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
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PAGECACHE_TAG_DIRTY,
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min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1))) {
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unsigned i;
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scanned = 1;
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for (i = 0; i < nr_pages; i++) {
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struct page *page = pvec.pages[i];
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/*
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* At this point we hold neither mapping->tree_lock nor
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* lock on the page itself: the page may be truncated or
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* invalidated (changing page->mapping to NULL), or even
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* swizzled back from swapper_space to tmpfs file
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* mapping
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*/
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lock_page(page);
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if (unlikely(page->mapping != mapping)) {
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unlock_page(page);
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continue;
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}
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if (!wbc->range_cyclic && page->index > end) {
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done = 1;
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unlock_page(page);
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continue;
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}
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if (wbc->sync_mode != WB_SYNC_NONE)
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wait_on_page_writeback(page);
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if (PageWriteback(page) ||
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!clear_page_dirty_for_io(page)) {
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unlock_page(page);
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continue;
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}
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if (writepage) {
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ret = (*writepage)(page, wbc);
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mapping_set_error(mapping, ret);
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} else {
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bio = __mpage_writepage(bio, page, get_block,
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&last_block_in_bio, &ret, wbc,
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page->mapping->a_ops->writepage);
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}
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if (unlikely(ret == AOP_WRITEPAGE_ACTIVATE))
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unlock_page(page);
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if (ret || (--(wbc->nr_to_write) <= 0))
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done = 1;
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if (wbc->nonblocking && bdi_write_congested(bdi)) {
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wbc->encountered_congestion = 1;
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done = 1;
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}
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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 (!scanned && !done) {
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/*
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* We hit the last page and there is more work to be done: wrap
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* back to the start of the file
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*/
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scanned = 1;
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index = 0;
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goto retry;
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}
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if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
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mapping->writeback_index = index;
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if (bio)
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mpage_bio_submit(WRITE, bio);
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return ret;
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}
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EXPORT_SYMBOL(mpage_writepages);
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@ -804,15 +720,15 @@ EXPORT_SYMBOL(mpage_writepages);
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int mpage_writepage(struct page *page, get_block_t get_block,
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struct writeback_control *wbc)
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{
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int ret = 0;
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struct bio *bio;
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sector_t last_block_in_bio = 0;
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bio = __mpage_writepage(NULL, page, get_block,
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&last_block_in_bio, &ret, wbc, NULL);
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if (bio)
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mpage_bio_submit(WRITE, bio);
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struct mpage_data mpd = {
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.bio = NULL,
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.last_block_in_bio = 0,
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.get_block = get_block,
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.use_writepage = 0,
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};
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int ret = __mpage_writepage(page, wbc, &mpd);
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if (mpd.bio)
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mpage_bio_submit(WRITE, mpd.bio);
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return ret;
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}
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EXPORT_SYMBOL(mpage_writepage);
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@ -12,7 +12,6 @@
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#ifdef CONFIG_BLOCK
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struct writeback_control;
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typedef int (writepage_t)(struct page *page, struct writeback_control *wbc);
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int mpage_readpages(struct address_space *mapping, struct list_head *pages,
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unsigned nr_pages, get_block_t get_block);
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@ -111,9 +111,15 @@ balance_dirty_pages_ratelimited(struct address_space *mapping)
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balance_dirty_pages_ratelimited_nr(mapping, 1);
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}
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typedef int (*writepage_t)(struct page *page, struct writeback_control *wbc,
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void *data);
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int pdflush_operation(void (*fn)(unsigned long), unsigned long arg0);
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extern int generic_writepages(struct address_space *mapping,
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struct writeback_control *wbc);
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int generic_writepages(struct address_space *mapping,
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struct writeback_control *wbc);
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int write_cache_pages(struct address_space *mapping,
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struct writeback_control *wbc, writepage_t writepage,
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void *data);
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int do_writepages(struct address_space *mapping, struct writeback_control *wbc);
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int sync_page_range(struct inode *inode, struct address_space *mapping,
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loff_t pos, loff_t count);
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@ -588,31 +588,27 @@ void __init page_writeback_init(void)
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}
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/**
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* generic_writepages - walk the list of dirty pages of the given address space and writepage() all of them.
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* write_cache_pages - walk the list of dirty pages of the given address space and write all of them.
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* @mapping: address space structure to write
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* @wbc: subtract the number of written pages from *@wbc->nr_to_write
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* @writepage: function called for each page
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* @data: data passed to writepage function
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*
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* This is a library function, which implements the writepages()
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* address_space_operation.
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*
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* If a page is already under I/O, generic_writepages() skips it, even
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* If a page is already under I/O, write_cache_pages() skips it, even
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* if it's dirty. This is desirable behaviour for memory-cleaning writeback,
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* but it is INCORRECT for data-integrity system calls such as fsync(). fsync()
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* and msync() need to guarantee that all the data which was dirty at the time
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* the call was made get new I/O started against them. If wbc->sync_mode is
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* WB_SYNC_ALL then we were called for data integrity and we must wait for
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* existing IO to complete.
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*
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* Derived from mpage_writepages() - if you fix this you should check that
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* also!
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*/
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int generic_writepages(struct address_space *mapping,
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struct writeback_control *wbc)
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int write_cache_pages(struct address_space *mapping,
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struct writeback_control *wbc, writepage_t writepage,
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void *data)
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{
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struct backing_dev_info *bdi = mapping->backing_dev_info;
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int ret = 0;
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int done = 0;
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int (*writepage)(struct page *page, struct writeback_control *wbc);
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struct pagevec pvec;
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int nr_pages;
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pgoff_t index;
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@ -625,12 +621,6 @@ int generic_writepages(struct address_space *mapping,
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return 0;
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}
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writepage = mapping->a_ops->writepage;
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/* deal with chardevs and other special file */
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if (!writepage)
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return 0;
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pagevec_init(&pvec, 0);
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if (wbc->range_cyclic) {
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index = mapping->writeback_index; /* Start from prev offset */
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@ -682,8 +672,7 @@ retry:
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continue;
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}
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ret = (*writepage)(page, wbc);
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mapping_set_error(mapping, ret);
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ret = (*writepage)(page, wbc, data);
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if (unlikely(ret == AOP_WRITEPAGE_ACTIVATE))
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unlock_page(page);
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@ -710,6 +699,38 @@ retry:
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mapping->writeback_index = index;
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return ret;
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}
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EXPORT_SYMBOL(write_cache_pages);
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/*
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* Function used by generic_writepages to call the real writepage
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* function and set the mapping flags on error
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*/
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static int __writepage(struct page *page, struct writeback_control *wbc,
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void *data)
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{
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struct address_space *mapping = data;
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int ret = mapping->a_ops->writepage(page, wbc);
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mapping_set_error(mapping, ret);
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return ret;
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}
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/**
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* generic_writepages - walk the list of dirty pages of the given address space and writepage() all of them.
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* @mapping: address space structure to write
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* @wbc: subtract the number of written pages from *@wbc->nr_to_write
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*
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* This is a library function, which implements the writepages()
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* address_space_operation.
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*/
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int generic_writepages(struct address_space *mapping,
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struct writeback_control *wbc)
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{
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/* deal with chardevs and other special file */
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if (!mapping->a_ops->writepage)
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return 0;
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return write_cache_pages(mapping, wbc, __writepage, mapping);
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}
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EXPORT_SYMBOL(generic_writepages);
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