Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
diff --git a/fs/mpage.c b/fs/mpage.c
new file mode 100644
index 0000000..e7d8d1a
--- /dev/null
+++ b/fs/mpage.c
@@ -0,0 +1,772 @@
+/*
+ * fs/mpage.c
+ *
+ * Copyright (C) 2002, Linus Torvalds.
+ *
+ * Contains functions related to preparing and submitting BIOs which contain
+ * multiple pagecache pages.
+ *
+ * 15May2002 akpm@zip.com.au
+ * Initial version
+ * 27Jun2002 axboe@suse.de
+ * use bio_add_page() to build bio's just the right size
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/mm.h>
+#include <linux/kdev_t.h>
+#include <linux/bio.h>
+#include <linux/fs.h>
+#include <linux/buffer_head.h>
+#include <linux/blkdev.h>
+#include <linux/highmem.h>
+#include <linux/prefetch.h>
+#include <linux/mpage.h>
+#include <linux/writeback.h>
+#include <linux/backing-dev.h>
+#include <linux/pagevec.h>
+
+/*
+ * I/O completion handler for multipage BIOs.
+ *
+ * The mpage code never puts partial pages into a BIO (except for end-of-file).
+ * If a page does not map to a contiguous run of blocks then it simply falls
+ * back to block_read_full_page().
+ *
+ * Why is this? If a page's completion depends on a number of different BIOs
+ * which can complete in any order (or at the same time) then determining the
+ * status of that page is hard. See end_buffer_async_read() for the details.
+ * There is no point in duplicating all that complexity.
+ */
+static int mpage_end_io_read(struct bio *bio, unsigned int bytes_done, int err)
+{
+ const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
+ struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;
+
+ if (bio->bi_size)
+ return 1;
+
+ do {
+ struct page *page = bvec->bv_page;
+
+ if (--bvec >= bio->bi_io_vec)
+ prefetchw(&bvec->bv_page->flags);
+
+ if (uptodate) {
+ SetPageUptodate(page);
+ } else {
+ ClearPageUptodate(page);
+ SetPageError(page);
+ }
+ unlock_page(page);
+ } while (bvec >= bio->bi_io_vec);
+ bio_put(bio);
+ return 0;
+}
+
+static int mpage_end_io_write(struct bio *bio, unsigned int bytes_done, int err)
+{
+ const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
+ struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;
+
+ if (bio->bi_size)
+ return 1;
+
+ do {
+ struct page *page = bvec->bv_page;
+
+ if (--bvec >= bio->bi_io_vec)
+ prefetchw(&bvec->bv_page->flags);
+
+ if (!uptodate)
+ SetPageError(page);
+ end_page_writeback(page);
+ } while (bvec >= bio->bi_io_vec);
+ bio_put(bio);
+ return 0;
+}
+
+struct bio *mpage_bio_submit(int rw, struct bio *bio)
+{
+ bio->bi_end_io = mpage_end_io_read;
+ if (rw == WRITE)
+ bio->bi_end_io = mpage_end_io_write;
+ submit_bio(rw, bio);
+ return NULL;
+}
+
+static struct bio *
+mpage_alloc(struct block_device *bdev,
+ sector_t first_sector, int nr_vecs,
+ unsigned int __nocast gfp_flags)
+{
+ struct bio *bio;
+
+ bio = bio_alloc(gfp_flags, nr_vecs);
+
+ if (bio == NULL && (current->flags & PF_MEMALLOC)) {
+ while (!bio && (nr_vecs /= 2))
+ bio = bio_alloc(gfp_flags, nr_vecs);
+ }
+
+ if (bio) {
+ bio->bi_bdev = bdev;
+ bio->bi_sector = first_sector;
+ }
+ return bio;
+}
+
+/*
+ * support function for mpage_readpages. The fs supplied get_block might
+ * return an up to date buffer. This is used to map that buffer into
+ * the page, which allows readpage to avoid triggering a duplicate call
+ * to get_block.
+ *
+ * The idea is to avoid adding buffers to pages that don't already have
+ * them. So when the buffer is up to date and the page size == block size,
+ * this marks the page up to date instead of adding new buffers.
+ */
+static void
+map_buffer_to_page(struct page *page, struct buffer_head *bh, int page_block)
+{
+ struct inode *inode = page->mapping->host;
+ struct buffer_head *page_bh, *head;
+ int block = 0;
+
+ if (!page_has_buffers(page)) {
+ /*
+ * don't make any buffers if there is only one buffer on
+ * the page and the page just needs to be set up to date
+ */
+ if (inode->i_blkbits == PAGE_CACHE_SHIFT &&
+ buffer_uptodate(bh)) {
+ SetPageUptodate(page);
+ return;
+ }
+ create_empty_buffers(page, 1 << inode->i_blkbits, 0);
+ }
+ head = page_buffers(page);
+ page_bh = head;
+ do {
+ if (block == page_block) {
+ page_bh->b_state = bh->b_state;
+ page_bh->b_bdev = bh->b_bdev;
+ page_bh->b_blocknr = bh->b_blocknr;
+ break;
+ }
+ page_bh = page_bh->b_this_page;
+ block++;
+ } while (page_bh != head);
+}
+
+/**
+ * mpage_readpages - populate an address space with some pages, and
+ * start reads against them.
+ *
+ * @mapping: the address_space
+ * @pages: The address of a list_head which contains the target pages. These
+ * pages have their ->index populated and are otherwise uninitialised.
+ *
+ * The page at @pages->prev has the lowest file offset, and reads should be
+ * issued in @pages->prev to @pages->next order.
+ *
+ * @nr_pages: The number of pages at *@pages
+ * @get_block: The filesystem's block mapper function.
+ *
+ * This function walks the pages and the blocks within each page, building and
+ * emitting large BIOs.
+ *
+ * If anything unusual happens, such as:
+ *
+ * - encountering a page which has buffers
+ * - encountering a page which has a non-hole after a hole
+ * - encountering a page with non-contiguous blocks
+ *
+ * then this code just gives up and calls the buffer_head-based read function.
+ * It does handle a page which has holes at the end - that is a common case:
+ * the end-of-file on blocksize < PAGE_CACHE_SIZE setups.
+ *
+ * BH_Boundary explanation:
+ *
+ * There is a problem. The mpage read code assembles several pages, gets all
+ * their disk mappings, and then submits them all. That's fine, but obtaining
+ * the disk mappings may require I/O. Reads of indirect blocks, for example.
+ *
+ * So an mpage read of the first 16 blocks of an ext2 file will cause I/O to be
+ * submitted in the following order:
+ * 12 0 1 2 3 4 5 6 7 8 9 10 11 13 14 15 16
+ * because the indirect block has to be read to get the mappings of blocks
+ * 13,14,15,16. Obviously, this impacts performance.
+ *
+ * So what we do it to allow the filesystem's get_block() function to set
+ * BH_Boundary when it maps block 11. BH_Boundary says: mapping of the block
+ * after this one will require I/O against a block which is probably close to
+ * this one. So you should push what I/O you have currently accumulated.
+ *
+ * This all causes the disk requests to be issued in the correct order.
+ */
+static struct bio *
+do_mpage_readpage(struct bio *bio, struct page *page, unsigned nr_pages,
+ sector_t *last_block_in_bio, get_block_t get_block)
+{
+ struct inode *inode = page->mapping->host;
+ const unsigned blkbits = inode->i_blkbits;
+ const unsigned blocks_per_page = PAGE_CACHE_SIZE >> blkbits;
+ const unsigned blocksize = 1 << blkbits;
+ sector_t block_in_file;
+ sector_t last_block;
+ sector_t blocks[MAX_BUF_PER_PAGE];
+ unsigned page_block;
+ unsigned first_hole = blocks_per_page;
+ struct block_device *bdev = NULL;
+ struct buffer_head bh;
+ int length;
+ int fully_mapped = 1;
+
+ if (page_has_buffers(page))
+ goto confused;
+
+ block_in_file = page->index << (PAGE_CACHE_SHIFT - blkbits);
+ last_block = (i_size_read(inode) + blocksize - 1) >> blkbits;
+
+ bh.b_page = page;
+ for (page_block = 0; page_block < blocks_per_page;
+ page_block++, block_in_file++) {
+ bh.b_state = 0;
+ if (block_in_file < last_block) {
+ if (get_block(inode, block_in_file, &bh, 0))
+ goto confused;
+ }
+
+ if (!buffer_mapped(&bh)) {
+ fully_mapped = 0;
+ if (first_hole == blocks_per_page)
+ first_hole = page_block;
+ continue;
+ }
+
+ /* some filesystems will copy data into the page during
+ * the get_block call, in which case we don't want to
+ * read it again. map_buffer_to_page copies the data
+ * we just collected from get_block into the page's buffers
+ * so readpage doesn't have to repeat the get_block call
+ */
+ if (buffer_uptodate(&bh)) {
+ map_buffer_to_page(page, &bh, page_block);
+ goto confused;
+ }
+
+ if (first_hole != blocks_per_page)
+ goto confused; /* hole -> non-hole */
+
+ /* Contiguous blocks? */
+ if (page_block && blocks[page_block-1] != bh.b_blocknr-1)
+ goto confused;
+ blocks[page_block] = bh.b_blocknr;
+ bdev = bh.b_bdev;
+ }
+
+ if (first_hole != blocks_per_page) {
+ char *kaddr = kmap_atomic(page, KM_USER0);
+ memset(kaddr + (first_hole << blkbits), 0,
+ PAGE_CACHE_SIZE - (first_hole << blkbits));
+ flush_dcache_page(page);
+ kunmap_atomic(kaddr, KM_USER0);
+ if (first_hole == 0) {
+ SetPageUptodate(page);
+ unlock_page(page);
+ goto out;
+ }
+ } else if (fully_mapped) {
+ SetPageMappedToDisk(page);
+ }
+
+ /*
+ * This page will go to BIO. Do we need to send this BIO off first?
+ */
+ if (bio && (*last_block_in_bio != blocks[0] - 1))
+ bio = mpage_bio_submit(READ, bio);
+
+alloc_new:
+ if (bio == NULL) {
+ bio = mpage_alloc(bdev, blocks[0] << (blkbits - 9),
+ min_t(int, nr_pages, bio_get_nr_vecs(bdev)),
+ GFP_KERNEL);
+ if (bio == NULL)
+ goto confused;
+ }
+
+ length = first_hole << blkbits;
+ if (bio_add_page(bio, page, length, 0) < length) {
+ bio = mpage_bio_submit(READ, bio);
+ goto alloc_new;
+ }
+
+ if (buffer_boundary(&bh) || (first_hole != blocks_per_page))
+ bio = mpage_bio_submit(READ, bio);
+ else
+ *last_block_in_bio = blocks[blocks_per_page - 1];
+out:
+ return bio;
+
+confused:
+ if (bio)
+ bio = mpage_bio_submit(READ, bio);
+ if (!PageUptodate(page))
+ block_read_full_page(page, get_block);
+ else
+ unlock_page(page);
+ goto out;
+}
+
+int
+mpage_readpages(struct address_space *mapping, struct list_head *pages,
+ unsigned nr_pages, get_block_t get_block)
+{
+ struct bio *bio = NULL;
+ unsigned page_idx;
+ sector_t last_block_in_bio = 0;
+ struct pagevec lru_pvec;
+
+ pagevec_init(&lru_pvec, 0);
+ for (page_idx = 0; page_idx < nr_pages; page_idx++) {
+ struct page *page = list_entry(pages->prev, struct page, lru);
+
+ prefetchw(&page->flags);
+ list_del(&page->lru);
+ if (!add_to_page_cache(page, mapping,
+ page->index, GFP_KERNEL)) {
+ bio = do_mpage_readpage(bio, page,
+ nr_pages - page_idx,
+ &last_block_in_bio, get_block);
+ if (!pagevec_add(&lru_pvec, page))
+ __pagevec_lru_add(&lru_pvec);
+ } else {
+ page_cache_release(page);
+ }
+ }
+ pagevec_lru_add(&lru_pvec);
+ BUG_ON(!list_empty(pages));
+ if (bio)
+ mpage_bio_submit(READ, bio);
+ return 0;
+}
+EXPORT_SYMBOL(mpage_readpages);
+
+/*
+ * This isn't called much at all
+ */
+int mpage_readpage(struct page *page, get_block_t get_block)
+{
+ struct bio *bio = NULL;
+ sector_t last_block_in_bio = 0;
+
+ bio = do_mpage_readpage(bio, page, 1,
+ &last_block_in_bio, get_block);
+ if (bio)
+ mpage_bio_submit(READ, bio);
+ return 0;
+}
+EXPORT_SYMBOL(mpage_readpage);
+
+/*
+ * Writing is not so simple.
+ *
+ * If the page has buffers then they will be used for obtaining the disk
+ * mapping. We only support pages which are fully mapped-and-dirty, with a
+ * special case for pages which are unmapped at the end: end-of-file.
+ *
+ * If the page has no buffers (preferred) then the page is mapped here.
+ *
+ * If all blocks are found to be contiguous then the page can go into the
+ * BIO. Otherwise fall back to the mapping's writepage().
+ *
+ * FIXME: This code wants an estimate of how many pages are still to be
+ * written, so it can intelligently allocate a suitably-sized BIO. For now,
+ * just allocate full-size (16-page) BIOs.
+ */
+static struct bio *
+__mpage_writepage(struct bio *bio, struct page *page, get_block_t get_block,
+ sector_t *last_block_in_bio, int *ret, struct writeback_control *wbc,
+ writepage_t writepage_fn)
+{
+ struct address_space *mapping = page->mapping;
+ struct inode *inode = page->mapping->host;
+ const unsigned blkbits = inode->i_blkbits;
+ unsigned long end_index;
+ const unsigned blocks_per_page = PAGE_CACHE_SIZE >> blkbits;
+ sector_t last_block;
+ sector_t block_in_file;
+ sector_t blocks[MAX_BUF_PER_PAGE];
+ unsigned page_block;
+ unsigned first_unmapped = blocks_per_page;
+ struct block_device *bdev = NULL;
+ int boundary = 0;
+ sector_t boundary_block = 0;
+ struct block_device *boundary_bdev = NULL;
+ int length;
+ struct buffer_head map_bh;
+ loff_t i_size = i_size_read(inode);
+
+ if (page_has_buffers(page)) {
+ struct buffer_head *head = page_buffers(page);
+ struct buffer_head *bh = head;
+
+ /* If they're all mapped and dirty, do it */
+ page_block = 0;
+ do {
+ BUG_ON(buffer_locked(bh));
+ if (!buffer_mapped(bh)) {
+ /*
+ * unmapped dirty buffers are created by
+ * __set_page_dirty_buffers -> mmapped data
+ */
+ if (buffer_dirty(bh))
+ goto confused;
+ if (first_unmapped == blocks_per_page)
+ first_unmapped = page_block;
+ continue;
+ }
+
+ if (first_unmapped != blocks_per_page)
+ goto confused; /* hole -> non-hole */
+
+ if (!buffer_dirty(bh) || !buffer_uptodate(bh))
+ goto confused;
+ if (page_block) {
+ if (bh->b_blocknr != blocks[page_block-1] + 1)
+ goto confused;
+ }
+ blocks[page_block++] = bh->b_blocknr;
+ boundary = buffer_boundary(bh);
+ if (boundary) {
+ boundary_block = bh->b_blocknr;
+ boundary_bdev = bh->b_bdev;
+ }
+ bdev = bh->b_bdev;
+ } while ((bh = bh->b_this_page) != head);
+
+ if (first_unmapped)
+ goto page_is_mapped;
+
+ /*
+ * Page has buffers, but they are all unmapped. The page was
+ * created by pagein or read over a hole which was handled by
+ * block_read_full_page(). If this address_space is also
+ * using mpage_readpages then this can rarely happen.
+ */
+ goto confused;
+ }
+
+ /*
+ * The page has no buffers: map it to disk
+ */
+ BUG_ON(!PageUptodate(page));
+ block_in_file = page->index << (PAGE_CACHE_SHIFT - blkbits);
+ last_block = (i_size - 1) >> blkbits;
+ map_bh.b_page = page;
+ for (page_block = 0; page_block < blocks_per_page; ) {
+
+ map_bh.b_state = 0;
+ if (get_block(inode, block_in_file, &map_bh, 1))
+ goto confused;
+ if (buffer_new(&map_bh))
+ unmap_underlying_metadata(map_bh.b_bdev,
+ map_bh.b_blocknr);
+ if (buffer_boundary(&map_bh)) {
+ boundary_block = map_bh.b_blocknr;
+ boundary_bdev = map_bh.b_bdev;
+ }
+ if (page_block) {
+ if (map_bh.b_blocknr != blocks[page_block-1] + 1)
+ goto confused;
+ }
+ blocks[page_block++] = map_bh.b_blocknr;
+ boundary = buffer_boundary(&map_bh);
+ bdev = map_bh.b_bdev;
+ if (block_in_file == last_block)
+ break;
+ block_in_file++;
+ }
+ BUG_ON(page_block == 0);
+
+ first_unmapped = page_block;
+
+page_is_mapped:
+ end_index = i_size >> PAGE_CACHE_SHIFT;
+ if (page->index >= end_index) {
+ /*
+ * The page straddles i_size. It must be zeroed out on each
+ * and every writepage invokation because it may be mmapped.
+ * "A file is mapped in multiples of the page size. For a file
+ * that is not a multiple of the page size, the remaining memory
+ * is zeroed when mapped, and writes to that region are not
+ * written out to the file."
+ */
+ unsigned offset = i_size & (PAGE_CACHE_SIZE - 1);
+ char *kaddr;
+
+ if (page->index > end_index || !offset)
+ goto confused;
+ kaddr = kmap_atomic(page, KM_USER0);
+ memset(kaddr + offset, 0, PAGE_CACHE_SIZE - offset);
+ flush_dcache_page(page);
+ kunmap_atomic(kaddr, KM_USER0);
+ }
+
+ /*
+ * This page will go to BIO. Do we need to send this BIO off first?
+ */
+ if (bio && *last_block_in_bio != blocks[0] - 1)
+ bio = mpage_bio_submit(WRITE, bio);
+
+alloc_new:
+ if (bio == NULL) {
+ bio = mpage_alloc(bdev, blocks[0] << (blkbits - 9),
+ bio_get_nr_vecs(bdev), GFP_NOFS|__GFP_HIGH);
+ if (bio == NULL)
+ goto confused;
+ }
+
+ /*
+ * Must try to add the page before marking the buffer clean or
+ * the confused fail path above (OOM) will be very confused when
+ * it finds all bh marked clean (i.e. it will not write anything)
+ */
+ length = first_unmapped << blkbits;
+ if (bio_add_page(bio, page, length, 0) < length) {
+ bio = mpage_bio_submit(WRITE, bio);
+ goto alloc_new;
+ }
+
+ /*
+ * OK, we have our BIO, so we can now mark the buffers clean. Make
+ * sure to only clean buffers which we know we'll be writing.
+ */
+ if (page_has_buffers(page)) {
+ struct buffer_head *head = page_buffers(page);
+ struct buffer_head *bh = head;
+ unsigned buffer_counter = 0;
+
+ do {
+ if (buffer_counter++ == first_unmapped)
+ break;
+ clear_buffer_dirty(bh);
+ bh = bh->b_this_page;
+ } while (bh != head);
+
+ /*
+ * we cannot drop the bh if the page is not uptodate
+ * or a concurrent readpage would fail to serialize with the bh
+ * and it would read from disk before we reach the platter.
+ */
+ if (buffer_heads_over_limit && PageUptodate(page))
+ try_to_free_buffers(page);
+ }
+
+ BUG_ON(PageWriteback(page));
+ set_page_writeback(page);
+ unlock_page(page);
+ if (boundary || (first_unmapped != blocks_per_page)) {
+ bio = mpage_bio_submit(WRITE, bio);
+ if (boundary_block) {
+ write_boundary_block(boundary_bdev,
+ boundary_block, 1 << blkbits);
+ }
+ } else {
+ *last_block_in_bio = blocks[blocks_per_page - 1];
+ }
+ goto out;
+
+confused:
+ if (bio)
+ bio = mpage_bio_submit(WRITE, bio);
+
+ if (writepage_fn) {
+ *ret = (*writepage_fn)(page, wbc);
+ } else {
+ *ret = -EAGAIN;
+ goto out;
+ }
+ /*
+ * The caller has a ref on the inode, so *mapping is stable
+ */
+ if (*ret) {
+ if (*ret == -ENOSPC)
+ set_bit(AS_ENOSPC, &mapping->flags);
+ else
+ set_bit(AS_EIO, &mapping->flags);
+ }
+out:
+ return bio;
+}
+
+/**
+ * mpage_writepages - walk the list of dirty pages of the given
+ * address space and writepage() all of them.
+ *
+ * @mapping: address space structure to write
+ * @wbc: subtract the number of written pages from *@wbc->nr_to_write
+ * @get_block: the filesystem's block mapper function.
+ * If this is NULL then use a_ops->writepage. Otherwise, go
+ * direct-to-BIO.
+ *
+ * This is a library function, which implements the writepages()
+ * address_space_operation.
+ *
+ * If a page is already under I/O, generic_writepages() skips it, even
+ * if it's dirty. This is desirable behaviour for memory-cleaning writeback,
+ * but it is INCORRECT for data-integrity system calls such as fsync(). fsync()
+ * and msync() need to guarantee that all the data which was dirty at the time
+ * the call was made get new I/O started against them. If wbc->sync_mode is
+ * WB_SYNC_ALL then we were called for data integrity and we must wait for
+ * existing IO to complete.
+ */
+int
+mpage_writepages(struct address_space *mapping,
+ struct writeback_control *wbc, get_block_t get_block)
+{
+ return __mpage_writepages(mapping, wbc, get_block,
+ mapping->a_ops->writepage);
+}
+
+int
+__mpage_writepages(struct address_space *mapping,
+ struct writeback_control *wbc, get_block_t get_block,
+ writepage_t writepage_fn)
+{
+ struct backing_dev_info *bdi = mapping->backing_dev_info;
+ struct bio *bio = NULL;
+ sector_t last_block_in_bio = 0;
+ int ret = 0;
+ int done = 0;
+ int (*writepage)(struct page *page, struct writeback_control *wbc);
+ struct pagevec pvec;
+ int nr_pages;
+ pgoff_t index;
+ pgoff_t end = -1; /* Inclusive */
+ int scanned = 0;
+ int is_range = 0;
+
+ if (wbc->nonblocking && bdi_write_congested(bdi)) {
+ wbc->encountered_congestion = 1;
+ return 0;
+ }
+
+ writepage = NULL;
+ if (get_block == NULL)
+ writepage = mapping->a_ops->writepage;
+
+ pagevec_init(&pvec, 0);
+ if (wbc->sync_mode == WB_SYNC_NONE) {
+ index = mapping->writeback_index; /* Start from prev offset */
+ } else {
+ index = 0; /* whole-file sweep */
+ scanned = 1;
+ }
+ if (wbc->start || wbc->end) {
+ index = wbc->start >> PAGE_CACHE_SHIFT;
+ end = wbc->end >> PAGE_CACHE_SHIFT;
+ is_range = 1;
+ scanned = 1;
+ }
+retry:
+ while (!done && (index <= end) &&
+ (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
+ PAGECACHE_TAG_DIRTY,
+ min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1))) {
+ unsigned i;
+
+ scanned = 1;
+ for (i = 0; i < nr_pages; i++) {
+ struct page *page = pvec.pages[i];
+
+ /*
+ * At this point we hold neither mapping->tree_lock nor
+ * lock on the page itself: the page may be truncated or
+ * invalidated (changing page->mapping to NULL), or even
+ * swizzled back from swapper_space to tmpfs file
+ * mapping
+ */
+
+ lock_page(page);
+
+ if (unlikely(page->mapping != mapping)) {
+ unlock_page(page);
+ continue;
+ }
+
+ if (unlikely(is_range) && page->index > end) {
+ done = 1;
+ unlock_page(page);
+ continue;
+ }
+
+ if (wbc->sync_mode != WB_SYNC_NONE)
+ wait_on_page_writeback(page);
+
+ if (PageWriteback(page) ||
+ !clear_page_dirty_for_io(page)) {
+ unlock_page(page);
+ continue;
+ }
+
+ if (writepage) {
+ ret = (*writepage)(page, wbc);
+ if (ret) {
+ if (ret == -ENOSPC)
+ set_bit(AS_ENOSPC,
+ &mapping->flags);
+ else
+ set_bit(AS_EIO,
+ &mapping->flags);
+ }
+ } else {
+ bio = __mpage_writepage(bio, page, get_block,
+ &last_block_in_bio, &ret, wbc,
+ writepage_fn);
+ }
+ if (ret || (--(wbc->nr_to_write) <= 0))
+ done = 1;
+ if (wbc->nonblocking && bdi_write_congested(bdi)) {
+ wbc->encountered_congestion = 1;
+ done = 1;
+ }
+ }
+ pagevec_release(&pvec);
+ cond_resched();
+ }
+ if (!scanned && !done) {
+ /*
+ * We hit the last page and there is more work to be done: wrap
+ * back to the start of the file
+ */
+ scanned = 1;
+ index = 0;
+ goto retry;
+ }
+ if (!is_range)
+ mapping->writeback_index = index;
+ if (bio)
+ mpage_bio_submit(WRITE, bio);
+ return ret;
+}
+EXPORT_SYMBOL(mpage_writepages);
+EXPORT_SYMBOL(__mpage_writepages);
+
+int mpage_writepage(struct page *page, get_block_t get_block,
+ struct writeback_control *wbc)
+{
+ int ret = 0;
+ struct bio *bio;
+ sector_t last_block_in_bio = 0;
+
+ bio = __mpage_writepage(NULL, page, get_block,
+ &last_block_in_bio, &ret, wbc, NULL);
+ if (bio)
+ mpage_bio_submit(WRITE, bio);
+
+ return ret;
+}
+EXPORT_SYMBOL(mpage_writepage);