} while (page_bh != head);
}
+/*
+ * This is the worker routine which does all the work of mapping the disk
+ * blocks and constructs largest possible bios, submits them for IO if the
+ * blocks are not contiguous on the disk.
+ *
+ * We pass a buffer_head back and forth and use its buffer_mapped() flag to
+ * represent the validity of its disk mapping and to decide when to do the next
+ * get_block() call.
+ */
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)
+ sector_t *last_block_in_bio, struct buffer_head *map_bh,
+ unsigned long *first_logical_block, get_block_t get_block)
{
struct inode *inode = page->mapping->host;
const unsigned blkbits = inode->i_blkbits;
const unsigned blocksize = 1 << blkbits;
sector_t block_in_file;
sector_t last_block;
+ sector_t last_block_in_file;
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;
+ unsigned nblocks;
+ unsigned relative_block;
if (page_has_buffers(page))
goto confused;
block_in_file = (sector_t)page->index << (PAGE_CACHE_SHIFT - blkbits);
- last_block = (i_size_read(inode) + blocksize - 1) >> blkbits;
+ last_block = block_in_file + nr_pages * blocks_per_page;
+ last_block_in_file = (i_size_read(inode) + blocksize - 1) >> blkbits;
+ if (last_block > last_block_in_file)
+ last_block = last_block_in_file;
+ page_block = 0;
+
+ /*
+ * Map blocks using the result from the previous get_blocks call first.
+ */
+ nblocks = map_bh->b_size >> blkbits;
+ if (buffer_mapped(map_bh) && block_in_file > *first_logical_block &&
+ block_in_file < (*first_logical_block + nblocks)) {
+ unsigned map_offset = block_in_file - *first_logical_block;
+ unsigned last = nblocks - map_offset;
+
+ for (relative_block = 0; ; relative_block++) {
+ if (relative_block == last) {
+ clear_buffer_mapped(map_bh);
+ break;
+ }
+ if (page_block == blocks_per_page)
+ break;
+ blocks[page_block] = map_bh->b_blocknr + map_offset +
+ relative_block;
+ page_block++;
+ block_in_file++;
+ }
+ bdev = map_bh->b_bdev;
+ }
+
+ /*
+ * Then do more get_blocks calls until we are done with this page.
+ */
+ map_bh->b_page = page;
+ while (page_block < blocks_per_page) {
+ map_bh->b_state = 0;
+ map_bh->b_size = 0;
- 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) {
- bh.b_size = blocksize;
- if (get_block(inode, block_in_file, &bh, 0))
+ map_bh->b_size = (last_block-block_in_file) << blkbits;
+ if (get_block(inode, block_in_file, map_bh, 0))
goto confused;
+ *first_logical_block = block_in_file;
}
- if (!buffer_mapped(&bh)) {
+ if (!buffer_mapped(map_bh)) {
fully_mapped = 0;
if (first_hole == blocks_per_page)
first_hole = page_block;
+ page_block++;
+ block_in_file++;
+ clear_buffer_mapped(map_bh);
continue;
}
* 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);
+ if (buffer_uptodate(map_bh)) {
+ map_buffer_to_page(page, map_bh, page_block);
goto confused;
}
goto confused; /* hole -> non-hole */
/* Contiguous blocks? */
- if (page_block && blocks[page_block-1] != bh.b_blocknr-1)
+ if (page_block && blocks[page_block-1] != map_bh->b_blocknr-1)
goto confused;
- blocks[page_block] = bh.b_blocknr;
- bdev = bh.b_bdev;
+ nblocks = map_bh->b_size >> blkbits;
+ for (relative_block = 0; ; relative_block++) {
+ if (relative_block == nblocks) {
+ clear_buffer_mapped(map_bh);
+ break;
+ } else if (page_block == blocks_per_page)
+ break;
+ blocks[page_block] = map_bh->b_blocknr+relative_block;
+ page_block++;
+ block_in_file++;
+ }
+ bdev = map_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);
+ zero_user_page(page, first_hole << blkbits,
+ PAGE_CACHE_SIZE - (first_hole << blkbits),
+ KM_USER0);
if (first_hole == 0) {
SetPageUptodate(page);
unlock_page(page);
goto alloc_new;
}
- if (buffer_boundary(&bh) || (first_hole != blocks_per_page))
+ if (buffer_boundary(map_bh) || (first_hole != blocks_per_page))
bio = mpage_bio_submit(READ, bio);
else
*last_block_in_bio = blocks[blocks_per_page - 1];
unsigned page_idx;
sector_t last_block_in_bio = 0;
struct pagevec lru_pvec;
+ struct buffer_head map_bh;
+ unsigned long first_logical_block = 0;
+ clear_buffer_mapped(&map_bh);
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);
page->index, GFP_KERNEL)) {
bio = do_mpage_readpage(bio, page,
nr_pages - page_idx,
- &last_block_in_bio, get_block);
+ &last_block_in_bio, &map_bh,
+ &first_logical_block,
+ get_block);
if (!pagevec_add(&lru_pvec, page))
__pagevec_lru_add(&lru_pvec);
} else {
{
struct bio *bio = NULL;
sector_t last_block_in_bio = 0;
+ struct buffer_head map_bh;
+ unsigned long first_logical_block = 0;
- bio = do_mpage_readpage(bio, page, 1,
- &last_block_in_bio, get_block);
+ clear_buffer_mapped(&map_bh);
+ bio = do_mpage_readpage(bio, page, 1, &last_block_in_bio,
+ &map_bh, &first_logical_block, get_block);
if (bio)
mpage_bio_submit(READ, bio);
return 0;
* 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 mpage_data {
+ struct bio *bio;
+ sector_t last_block_in_bio;
+ get_block_t *get_block;
+ unsigned use_writepage;
+};
+
+static int __mpage_writepage(struct page *page, struct writeback_control *wbc,
+ void *data)
{
+ struct mpage_data *mpd = data;
+ struct bio *bio = mpd->bio;
struct address_space *mapping = page->mapping;
struct inode *inode = page->mapping->host;
const unsigned blkbits = inode->i_blkbits;
int length;
struct buffer_head map_bh;
loff_t i_size = i_size_read(inode);
+ int ret = 0;
if (page_has_buffers(page)) {
struct buffer_head *head = page_buffers(page);
map_bh.b_state = 0;
map_bh.b_size = 1 << blkbits;
- if (get_block(inode, block_in_file, &map_bh, 1))
+ if (mpd->get_block(inode, block_in_file, &map_bh, 1))
goto confused;
if (buffer_new(&map_bh))
unmap_underlying_metadata(map_bh.b_bdev,
* 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);
+ zero_user_page(page, offset, PAGE_CACHE_SIZE - offset,
+ 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)
+ if (bio && mpd->last_block_in_bio != blocks[0] - 1)
bio = mpage_bio_submit(WRITE, bio);
alloc_new:
boundary_block, 1 << blkbits);
}
} else {
- *last_block_in_bio = blocks[blocks_per_page - 1];
+ mpd->last_block_in_bio = blocks[blocks_per_page - 1];
}
goto out;
if (bio)
bio = mpage_bio_submit(WRITE, bio);
- if (writepage_fn) {
- *ret = (*writepage_fn)(page, wbc);
+ if (mpd->use_writepage) {
+ ret = mapping->a_ops->writepage(page, wbc);
} else {
- *ret = -EAGAIN;
+ 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);
- }
+ mapping_set_error(mapping, ret);
out:
- return bio;
+ mpd->bio = bio;
+ return ret;
}
/**
mpage_writepages(struct address_space *mapping,
struct writeback_control *wbc, get_block_t get_block)
{
- 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;
+ int ret;
+
+ if (!get_block)
+ ret = generic_writepages(mapping, wbc);
+ else {
+ struct mpage_data mpd = {
+ .bio = NULL,
+ .last_block_in_bio = 0,
+ .get_block = get_block,
+ .use_writepage = 1,
+ };
+
+ ret = write_cache_pages(mapping, wbc, __mpage_writepage, &mpd);
+ if (mpd.bio)
+ mpage_bio_submit(WRITE, mpd.bio);
}
-
- 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,
- page->mapping->a_ops->writepage);
- }
- if (unlikely(ret == AOP_WRITEPAGE_ACTIVATE))
- unlock_page(page);
- 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);
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);
-
+ struct mpage_data mpd = {
+ .bio = NULL,
+ .last_block_in_bio = 0,
+ .get_block = get_block,
+ .use_writepage = 0,
+ };
+ int ret = __mpage_writepage(page, wbc, &mpd);
+ if (mpd.bio)
+ mpage_bio_submit(WRITE, mpd.bio);
return ret;
}
EXPORT_SYMBOL(mpage_writepage);
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff