Re: [Ext2-devel] [RFC] Adding multiple block allocation
From: Mingming Cao
Date: Fri Apr 29 2005 - 19:41:18 EST
On Fri, 2005-04-29 at 19:22 +0530, Suparna Bhattacharya wrote:
> On Thu, Apr 28, 2005 at 12:14:24PM -0700, Mingming Cao wrote:
> > Currently ext3_get_block()/ext3_new_block() only allocate one block at a
> > time. To allocate multiple blocks, the caller, for example, ext3 direct
> > IO routine, has to invoke ext3_get_block() many times. This is quite
> > inefficient for sequential IO workload.
> >
> > The benefit of a real get_blocks() include
> > 1) increase the possibility to get contiguous blocks, reduce possibility
> > of fragmentation due to interleaved allocations from other threads.
> > (should good for non reservation case)
> > 2) Reduces CPU cycles spent in repeated get_block() calls
> > 3) Batch meta data update and journaling in one short
> > 4) Could possibly speed up future get_blocks() look up by cache the last
> > mapped blocks in inode.
> >
>
> And here is the patch to make mpage_writepages use get_blocks() for
> multiple block lookup/allocation. It performs a radix-tree contiguous
> pages lookup, and issues a get_blocks for the range together. It maintains
> an mpageio structure to track intermediate mapping state, somewhat
> like the DIO code.
>
> It does need some more testing, especially block_size < PAGE_SIZE.
> The JFS workaround can be dropped if the JFS get_blocks fix from
> Dave Kleikamp is integrated.
>
> Review feedback would be welcome.
>
> Mingming,
> Let me know if you have a chance to try this out with your patch.
>
> Regards
> Suparna
>
> --
> Suparna Bhattacharya (suparna@xxxxxxxxxx)
> Linux Technology Center
> IBM Software Lab, India
>
>
> diff -urp -X dontdiff linux-2.6.12-rc3/fs/buffer.c linux-2.6.12-rc3-getblocks/fs/buffer.c
> --- linux-2.6.12-rc3/fs/buffer.c 2005-04-21 05:33:15.000000000 +0530
> +++ linux-2.6.12-rc3-getblocks/fs/buffer.c 2005-04-22 15:08:33.000000000 +0530
> @@ -2514,53 +2514,10 @@ EXPORT_SYMBOL(nobh_commit_write);
> * that it tries to operate without attaching bufferheads to
> * the page.
> */
> -int nobh_writepage(struct page *page, get_block_t *get_block,
> - struct writeback_control *wbc)
> +int nobh_writepage(struct page *page, get_blocks_t *get_blocks,
> + struct writeback_control *wbc, writepage_t bh_writepage_fn)
> {
> - struct inode * const inode = page->mapping->host;
> - loff_t i_size = i_size_read(inode);
> - const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
> - unsigned offset;
> - void *kaddr;
> - int ret;
> -
> - /* Is the page fully inside i_size? */
> - if (page->index < end_index)
> - goto out;
> -
> - /* Is the page fully outside i_size? (truncate in progress) */
> - offset = i_size & (PAGE_CACHE_SIZE-1);
> - if (page->index >= end_index+1 || !offset) {
> - /*
> - * The page may have dirty, unmapped buffers. For example,
> - * they may have been added in ext3_writepage(). Make them
> - * freeable here, so the page does not leak.
> - */
> -#if 0
> - /* Not really sure about this - do we need this ? */
> - if (page->mapping->a_ops->invalidatepage)
> - page->mapping->a_ops->invalidatepage(page, offset);
> -#endif
> - unlock_page(page);
> - return 0; /* don't care */
> - }
> -
> - /*
> - * The page straddles i_size. It must be zeroed out on each and every
> - * writepage invocation 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."
> - */
> - kaddr = kmap_atomic(page, KM_USER0);
> - memset(kaddr + offset, 0, PAGE_CACHE_SIZE - offset);
> - flush_dcache_page(page);
> - kunmap_atomic(kaddr, KM_USER0);
> -out:
> - ret = mpage_writepage(page, get_block, wbc);
> - if (ret == -EAGAIN)
> - ret = __block_write_full_page(inode, page, get_block, wbc);
> - return ret;
> + return mpage_writepage(page, get_blocks, wbc, bh_writepage_fn);
> }
> EXPORT_SYMBOL(nobh_writepage);
>
> diff -urp -X dontdiff linux-2.6.12-rc3/fs/ext2/inode.c linux-2.6.12-rc3-getblocks/fs/ext2/inode.c
> --- linux-2.6.12-rc3/fs/ext2/inode.c 2005-04-21 05:33:15.000000000 +0530
> +++ linux-2.6.12-rc3-getblocks/fs/ext2/inode.c 2005-04-22 16:30:42.000000000 +0530
> @@ -639,12 +639,6 @@ ext2_nobh_prepare_write(struct file *fil
> return nobh_prepare_write(page,from,to,ext2_get_block);
> }
>
> -static int ext2_nobh_writepage(struct page *page,
> - struct writeback_control *wbc)
> -{
> - return nobh_writepage(page, ext2_get_block, wbc);
> -}
> -
> static sector_t ext2_bmap(struct address_space *mapping, sector_t block)
> {
> return generic_block_bmap(mapping,block,ext2_get_block);
> @@ -662,6 +656,12 @@ ext2_get_blocks(struct inode *inode, sec
> return ret;
> }
>
> +static int ext2_nobh_writepage(struct page *page,
> + struct writeback_control *wbc)
> +{
> + return nobh_writepage(page, ext2_get_blocks, wbc, ext2_writepage);
> +}
> +
> static ssize_t
> ext2_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
> loff_t offset, unsigned long nr_segs)
> @@ -676,7 +676,8 @@ ext2_direct_IO(int rw, struct kiocb *ioc
> static int
> ext2_writepages(struct address_space *mapping, struct writeback_control *wbc)
> {
> - return mpage_writepages(mapping, wbc, ext2_get_block);
> + return __mpage_writepages(mapping, wbc, ext2_get_blocks,
> + ext2_writepage);
> }
>
> struct address_space_operations ext2_aops = {
> diff -urp -X dontdiff linux-2.6.12-rc3/fs/ext3/inode.c linux-2.6.12-rc3-getblocks/fs/ext3/inode.c
> --- linux-2.6.12-rc3/fs/ext3/inode.c 2005-04-21 05:33:15.000000000 +0530
> +++ linux-2.6.12-rc3-getblocks/fs/ext3/inode.c 2005-04-22 15:08:33.000000000 +0530
> @@ -866,10 +866,10 @@ get_block:
> return ret;
> }
>
> -static int ext3_writepages_get_block(struct inode *inode, sector_t iblock,
> - struct buffer_head *bh, int create)
> +static int ext3_writepages_get_blocks(struct inode *inode, sector_t iblock,
> + unsigned long max_blocks, struct buffer_head *bh, int create)
> {
> - return ext3_direct_io_get_blocks(inode, iblock, 1, bh, create);
> + return ext3_direct_io_get_blocks(inode, iblock, max_blocks, bh, create);
> }
>
> /*
> @@ -1369,11 +1369,11 @@ ext3_writeback_writepages(struct address
> return ret;
> }
>
> - ret = __mpage_writepages(mapping, wbc, ext3_writepages_get_block,
> + ret = __mpage_writepages(mapping, wbc, ext3_writepages_get_blocks,
> ext3_writeback_writepage_helper);
>
> /*
> - * Need to reaquire the handle since ext3_writepages_get_block()
> + * Need to reaquire the handle since ext3_writepages_get_blocks()
> * can restart the handle
> */
> handle = journal_current_handle();
> @@ -1402,7 +1402,8 @@ static int ext3_writeback_writepage(stru
> }
>
> if (test_opt(inode->i_sb, NOBH))
> - ret = nobh_writepage(page, ext3_get_block, wbc);
> + ret = nobh_writepage(page, ext3_writepages_get_blocks, wbc,
> + ext3_writeback_writepage_helper);
> else
> ret = block_write_full_page(page, ext3_get_block, wbc);
>
> diff -urp -X dontdiff linux-2.6.12-rc3/fs/ext3/super.c linux-2.6.12-rc3-getblocks/fs/ext3/super.c
> --- linux-2.6.12-rc3/fs/ext3/super.c 2005-04-21 05:33:15.000000000 +0530
> +++ linux-2.6.12-rc3-getblocks/fs/ext3/super.c 2005-04-22 15:08:33.000000000 +0530
> @@ -1321,6 +1321,7 @@ static int ext3_fill_super (struct super
> sbi->s_resgid = le16_to_cpu(es->s_def_resgid);
>
> set_opt(sbi->s_mount_opt, RESERVATION);
> + set_opt(sbi->s_mount_opt, NOBH); /* temp: set nobh default */
>
> if (!parse_options ((char *) data, sb, &journal_inum, NULL, 0))
> goto failed_mount;
> @@ -1567,6 +1568,7 @@ static int ext3_fill_super (struct super
> printk(KERN_ERR "EXT3-fs: Journal does not support "
> "requested data journaling mode\n");
> goto failed_mount3;
> + set_opt(sbi->s_mount_opt, NOBH); /* temp: set nobh default */
> }
> default:
> break;
> @@ -1584,6 +1586,7 @@ static int ext3_fill_super (struct super
> "its supported only with writeback mode\n");
> clear_opt(sbi->s_mount_opt, NOBH);
> }
> + printk("NOBH option set\n");
> }
> /*
> * The journal_load will have done any necessary log recovery,
> diff -urp -X dontdiff linux-2.6.12-rc3/fs/hfs/inode.c linux-2.6.12-rc3-getblocks/fs/hfs/inode.c
> --- linux-2.6.12-rc3/fs/hfs/inode.c 2005-04-21 05:33:15.000000000 +0530
> +++ linux-2.6.12-rc3-getblocks/fs/hfs/inode.c 2005-04-22 15:08:33.000000000 +0530
> @@ -124,7 +124,7 @@ static ssize_t hfs_direct_IO(int rw, str
> static int hfs_writepages(struct address_space *mapping,
> struct writeback_control *wbc)
> {
> - return mpage_writepages(mapping, wbc, hfs_get_block);
> + return mpage_writepages(mapping, wbc, hfs_get_blocks);
> }
>
> struct address_space_operations hfs_btree_aops = {
> diff -urp -X dontdiff linux-2.6.12-rc3/fs/hfsplus/inode.c linux-2.6.12-rc3-getblocks/fs/hfsplus/inode.c
> --- linux-2.6.12-rc3/fs/hfsplus/inode.c 2005-04-21 05:33:15.000000000 +0530
> +++ linux-2.6.12-rc3-getblocks/fs/hfsplus/inode.c 2005-04-22 15:08:33.000000000 +0530
> @@ -121,7 +121,7 @@ static ssize_t hfsplus_direct_IO(int rw,
> static int hfsplus_writepages(struct address_space *mapping,
> struct writeback_control *wbc)
> {
> - return mpage_writepages(mapping, wbc, hfsplus_get_block);
> + return mpage_writepages(mapping, wbc, hfsplus_get_blocks);
> }
>
> struct address_space_operations hfsplus_btree_aops = {
> diff -urp -X dontdiff linux-2.6.12-rc3/fs/jfs/inode.c linux-2.6.12-rc3-getblocks/fs/jfs/inode.c
> --- linux-2.6.12-rc3/fs/jfs/inode.c 2005-04-21 05:33:15.000000000 +0530
> +++ linux-2.6.12-rc3-getblocks/fs/jfs/inode.c 2005-04-22 16:27:19.000000000 +0530
> @@ -267,21 +267,41 @@ jfs_get_blocks(struct inode *ip, sector_
> return rc;
> }
>
> +static int
> +jfs_mpage_get_blocks(struct inode *ip, sector_t lblock, unsigned long
> + max_blocks, struct buffer_head *bh_result, int create)
> +{
> + /*
> + * fixme: temporary workaround: return one block at a time until
> + * we figure out why we see exposures with truncate on
> + * allocating multiple blocks in one shot.
> + */
> + return jfs_get_blocks(ip, lblock, 1, bh_result, create);
> +}
> +
> static int jfs_get_block(struct inode *ip, sector_t lblock,
> struct buffer_head *bh_result, int create)
> {
> return jfs_get_blocks(ip, lblock, 1, bh_result, create);
> }
>
> +static int jfs_bh_writepage(struct page *page,
> + struct writeback_control *wbc)
> +{
> + return block_write_full_page(page, jfs_get_block, wbc);
> +}
> +
> +
> static int jfs_writepage(struct page *page, struct writeback_control *wbc)
> {
> - return nobh_writepage(page, jfs_get_block, wbc);
> + return nobh_writepage(page, jfs_mpage_get_blocks, wbc, jfs_bh_writepage);
> }
>
> static int jfs_writepages(struct address_space *mapping,
> struct writeback_control *wbc)
> {
> - return mpage_writepages(mapping, wbc, jfs_get_block);
> + return __mpage_writepages(mapping, wbc, jfs_mpage_get_blocks,
> + jfs_bh_writepage);
> }
>
> static int jfs_readpage(struct file *file, struct page *page)
> diff -urp -X dontdiff linux-2.6.12-rc3/fs/mpage.c linux-2.6.12-rc3-getblocks/fs/mpage.c
> --- linux-2.6.12-rc3/fs/mpage.c 2005-04-21 05:33:15.000000000 +0530
> +++ linux-2.6.12-rc3-getblocks/fs/mpage.c 2005-04-22 16:19:14.000000000 +0530
> @@ -370,6 +370,67 @@ int mpage_readpage(struct page *page, ge
> }
> EXPORT_SYMBOL(mpage_readpage);
>
> +struct mpageio {
> + struct bio *bio;
> + struct buffer_head map_bh;
> + unsigned long block_in_file;
> + unsigned long final_block_in_request;
> + sector_t long block_in_bio;
> + int boundary;
> + sector_t boundary_block;
> + struct block_device *boundary_bdev;
> +};
> +
> +/*
> + * Maps as many contiguous disk blocks as it can within the range of
> + * the request, and returns the total number of contiguous mapped
> + * blocks in the mpageio.
> + */
> +static unsigned long mpage_get_more_blocks(struct mpageio *mio,
> + struct inode *inode, get_blocks_t get_blocks)
> +{
> + struct buffer_head map_bh = {.b_state = 0};
> + unsigned long mio_nblocks = mio->map_bh.b_size >> inode->i_blkbits;
> + unsigned long first_unmapped = mio->block_in_file + mio_nblocks;
> + unsigned long next_contig_block = mio->map_bh.b_blocknr + mio_nblocks;
> +
> + while ((first_unmapped < mio->final_block_in_request) &&
> + (mio->map_bh.b_size < PAGE_SIZE)) {
> +
> + if (get_blocks(inode, first_unmapped,
> + mio->final_block_in_request - first_unmapped,
> + &map_bh, 1))
> + break;
> + if (mio_nblocks && ((map_bh.b_blocknr != next_contig_block) ||
> + map_bh.b_bdev != mio->map_bh.b_bdev))
> + break;
> +
> + if (buffer_new(&map_bh)) {
> + int i = 0;
> + for (; i < map_bh.b_size >> inode->i_blkbits; i++)
> + unmap_underlying_metadata(map_bh.b_bdev,
> + map_bh.b_blocknr + i);
> + }
> +
> + if (buffer_boundary(&map_bh)) {
> + mio->boundary = 1;
> + mio->boundary_block = map_bh.b_blocknr;
> + mio->boundary_bdev = map_bh.b_bdev;
> + }
> + if (mio_nblocks == 0) {
> + mio->map_bh.b_bdev = map_bh.b_bdev;
> + mio->map_bh.b_blocknr = map_bh.b_blocknr;
> + }
> +
> + mio_nblocks += map_bh.b_size >> inode->i_blkbits;
> + first_unmapped = mio->block_in_file + mio_nblocks;
> + next_contig_block = mio->map_bh.b_blocknr + mio_nblocks;
> + mio->map_bh.b_size += map_bh.b_size;
> + }
> +
> + return mio_nblocks;
> +}
> +
> /*
> * Writing is not so simple.
> *
> @@ -386,9 +447,9 @@ EXPORT_SYMBOL(mpage_readpage);
> * 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,
> +static int
> +__mpage_writepage(struct mpageio *mio, struct page *page,
> + get_blocks_t get_blocks, struct writeback_control *wbc,
> writepage_t writepage_fn)
> {
> struct address_space *mapping = page->mapping;
> @@ -396,9 +457,8 @@ __mpage_writepage(struct bio *bio, struc
> 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 last_block, blocks_to_skip;
> 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;
> @@ -406,8 +466,10 @@ __mpage_writepage(struct bio *bio, struc
> 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);
> + struct buffer_head *map_bh = &mio->map_bh;
> + struct bio *bio = mio->bio;
> + int ret = 0;
>
> if (page_has_buffers(page)) {
> struct buffer_head *head = page_buffers(page);
> @@ -435,10 +497,13 @@ __mpage_writepage(struct bio *bio, struc
> if (!buffer_dirty(bh) || !buffer_uptodate(bh))
> goto confused;
> if (page_block) {
> - if (bh->b_blocknr != blocks[page_block-1] + 1)
> + if (bh->b_blocknr != map_bh->b_blocknr
> + + page_block)
> goto confused;
> + } else {
> + map_bh->b_blocknr = bh->b_blocknr;
> + map_bh->b_size = PAGE_SIZE;
> }
> - blocks[page_block++] = bh->b_blocknr;
> boundary = buffer_boundary(bh);
> if (boundary) {
> boundary_block = bh->b_blocknr;
> @@ -465,33 +530,30 @@ __mpage_writepage(struct bio *bio, struc
> 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++;
> + blocks_to_skip = block_in_file - mio->block_in_file;
> + mio->block_in_file = block_in_file;
> + if (blocks_to_skip < (map_bh->b_size >> blkbits)) {
> + map_bh->b_blocknr += blocks_to_skip;
> + map_bh->b_size -= blocks_to_skip << blkbits;
> + } else {
> + map_bh->b_state = 0;
> + map_bh->b_size = 0;
> + if (mio->final_block_in_request > last_block)
> + mio->final_block_in_request = last_block;
> + mpage_get_more_blocks(mio, inode, get_blocks);
> }
> - BUG_ON(page_block == 0);
> + if (map_bh->b_size < PAGE_SIZE)
> + goto confused;
>
> - first_unmapped = page_block;
> + if (mio->boundary && (mio->boundary_block < map_bh->b_blocknr
> + + blocks_per_page)) {
> + boundary = 1;
> + boundary_block = mio->boundary_block;
> + boundary_bdev = mio->boundary_bdev;
> + }
> +
> + bdev = map_bh->b_bdev;
> + first_unmapped = blocks_per_page;
>
> page_is_mapped:
> end_index = i_size >> PAGE_CACHE_SHIFT;
> @@ -518,12 +580,16 @@ page_is_mapped:
> /*
> * 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 && mio->block_in_bio != map_bh->b_blocknr - 1)
> bio = mpage_bio_submit(WRITE, bio);
>
> alloc_new:
> if (bio == NULL) {
> - bio = mpage_alloc(bdev, blocks[0] << (blkbits - 9),
> + /*
> + * Fixme: bio size can be limited to final_block - block, or
> + * even mio->map_bh.b_size
> + */
> + bio = mpage_alloc(bdev, map_bh->b_blocknr << (blkbits - 9),
> bio_get_nr_vecs(bdev), GFP_NOFS|__GFP_HIGH);
> if (bio == NULL)
> goto confused;
> @@ -539,6 +605,9 @@ alloc_new:
> bio = mpage_bio_submit(WRITE, bio);
> goto alloc_new;
> }
> + map_bh->b_blocknr += blocks_per_page;
> + map_bh->b_size -= PAGE_SIZE;
> + mio->block_in_file += blocks_per_page;
>
> /*
> * OK, we have our BIO, so we can now mark the buffers clean. Make
> @@ -575,7 +644,8 @@ alloc_new:
> boundary_block, 1 << blkbits);
> }
> } else {
> - *last_block_in_bio = blocks[blocks_per_page - 1];
> + /* we can pack more pages into the bio, don't submit yet */
> + mio->block_in_bio = map_bh->b_blocknr - 1;
> }
> goto out;
>
> @@ -584,22 +654,23 @@ confused:
> bio = mpage_bio_submit(WRITE, bio);
>
> if (writepage_fn) {
> - *ret = (*writepage_fn)(page, wbc);
> + ret = (*writepage_fn)(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)
> + if (ret) {
> + if (ret == -ENOSPC)
> set_bit(AS_ENOSPC, &mapping->flags);
> else
> set_bit(AS_EIO, &mapping->flags);
> }
> out:
> - return bio;
> + mio->bio = bio;
> + return ret;
> }
>
> /**
> @@ -625,20 +696,21 @@ out:
> */
> int
> mpage_writepages(struct address_space *mapping,
> - struct writeback_control *wbc, get_block_t get_block)
> + struct writeback_control *wbc, get_blocks_t get_blocks)
> {
> - return __mpage_writepages(mapping, wbc, get_block,
> + return __mpage_writepages(mapping, wbc, get_blocks,
> mapping->a_ops->writepage);
> }
>
> int
> __mpage_writepages(struct address_space *mapping,
> - struct writeback_control *wbc, get_block_t get_block,
> + struct writeback_control *wbc, get_blocks_t get_blocks,
> writepage_t writepage_fn)
> {
> struct backing_dev_info *bdi = mapping->backing_dev_info;
> + struct inode *inode = mapping->host;
> + const unsigned blkbits = inode->i_blkbits;
> 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);
> @@ -648,6 +720,9 @@ __mpage_writepages(struct address_space
> pgoff_t end = -1; /* Inclusive */
> int scanned = 0;
> int is_range = 0;
> + struct mpageio mio = {
> + .bio = NULL
> + };
>
> if (wbc->nonblocking && bdi_write_congested(bdi)) {
> wbc->encountered_congestion = 1;
> @@ -655,7 +730,7 @@ __mpage_writepages(struct address_space
> }
>
> writepage = NULL;
> - if (get_block == NULL)
> + if (get_blocks == NULL)
> writepage = mapping->a_ops->writepage;
>
> pagevec_init(&pvec, 0);
> @@ -672,12 +747,15 @@ __mpage_writepages(struct address_space
> scanned = 1;
> }
> retry:
> + down_read(&inode->i_alloc_sem);
> while (!done && (index <= end) &&
> - (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
> - PAGECACHE_TAG_DIRTY,
> + (nr_pages = pagevec_contig_lookup_tag(&pvec, mapping,
> + &index, PAGECACHE_TAG_DIRTY,
> min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1))) {
> unsigned i;
>
> + mio.final_block_in_request = min(index, end) <<
> + (PAGE_CACHE_SHIFT - blkbits);
> scanned = 1;
> for (i = 0; i < nr_pages; i++) {
> struct page *page = pvec.pages[i];
> @@ -702,7 +780,7 @@ retry:
> unlock_page(page);
> continue;
> }
> -
> +
> if (wbc->sync_mode != WB_SYNC_NONE)
> wait_on_page_writeback(page);
>
> @@ -723,9 +801,9 @@ retry:
> &mapping->flags);
> }
> } else {
> - bio = __mpage_writepage(bio, page, get_block,
> - &last_block_in_bio, &ret, wbc,
> - writepage_fn);
> + ret = __mpage_writepage(&mio, page, get_blocks,
> + wbc, writepage_fn);
> + bio = mio.bio;
> }
> if (ret || (--(wbc->nr_to_write) <= 0))
> done = 1;
> @@ -737,6 +815,9 @@ retry:
> pagevec_release(&pvec);
> cond_resched();
> }
> +
> + up_read(&inode->i_alloc_sem);
> +
> if (!scanned && !done) {
> /*
> * We hit the last page and there is more work to be done: wrap
> @@ -755,17 +836,23 @@ retry:
> EXPORT_SYMBOL(mpage_writepages);
> EXPORT_SYMBOL(__mpage_writepages);
>
> -int mpage_writepage(struct page *page, get_block_t get_block,
> - struct writeback_control *wbc)
> +int mpage_writepage(struct page *page, get_blocks_t get_blocks,
> + struct writeback_control *wbc, writepage_t writepage_fn)
> {
> 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 address_space *mapping = page->mapping;
> + struct inode *inode = mapping->host;
> + const unsigned blkbits = inode->i_blkbits;
> + struct mpageio mio = {
> + .final_block_in_request = (page->index + 1) << (PAGE_CACHE_SHIFT
> + - blkbits)
> + };
> +
> + dump_stack();
> + ret = __mpage_writepage(&mio, page, get_blocks,
> + wbc, writepage_fn);
> + if (mio.bio)
> + mpage_bio_submit(WRITE, mio.bio);
>
> return ret;
> }
> diff -urp -X dontdiff linux-2.6.12-rc3/include/linux/buffer_head.h linux-2.6.12-rc3-getblocks/include/linux/buffer_head.h
> --- linux-2.6.12-rc3/include/linux/buffer_head.h 2005-04-21 05:33:16.000000000 +0530
> +++ linux-2.6.12-rc3-getblocks/include/linux/buffer_head.h 2005-04-22 15:08:33.000000000 +0530
> @@ -203,8 +203,8 @@ int file_fsync(struct file *, struct den
> int nobh_prepare_write(struct page*, unsigned, unsigned, get_block_t*);
> int nobh_commit_write(struct file *, struct page *, unsigned, unsigned);
> int nobh_truncate_page(struct address_space *, loff_t);
> -int nobh_writepage(struct page *page, get_block_t *get_block,
> - struct writeback_control *wbc);
> +int nobh_writepage(struct page *page, get_blocks_t *get_blocks,
> + struct writeback_control *wbc, writepage_t bh_writepage);
>
>
> /*
> diff -urp -X dontdiff linux-2.6.12-rc3/include/linux/fs.h linux-2.6.12-rc3-getblocks/include/linux/fs.h
> --- linux-2.6.12-rc3/include/linux/fs.h 2005-04-21 05:33:16.000000000 +0530
> +++ linux-2.6.12-rc3-getblocks/include/linux/fs.h 2005-04-22 15:08:33.000000000 +0530
> @@ -304,6 +304,8 @@ struct address_space;
> struct writeback_control;
> struct kiocb;
>
> +typedef int (writepage_t)(struct page *page, struct writeback_control *wbc);
> +
> struct address_space_operations {
> int (*writepage)(struct page *page, struct writeback_control *wbc);
> int (*readpage)(struct file *, struct page *);
> diff -urp -X dontdiff linux-2.6.12-rc3/include/linux/mpage.h linux-2.6.12-rc3-getblocks/include/linux/mpage.h
> --- linux-2.6.12-rc3/include/linux/mpage.h 2005-04-21 05:33:16.000000000 +0530
> +++ linux-2.6.12-rc3-getblocks/include/linux/mpage.h 2005-04-22 15:08:33.000000000 +0530
> @@ -11,17 +11,16 @@
> */
>
> struct writeback_control;
> -typedef int (writepage_t)(struct page *page, struct writeback_control *wbc);
>
> int mpage_readpages(struct address_space *mapping, struct list_head *pages,
> unsigned nr_pages, get_block_t get_block);
> int mpage_readpage(struct page *page, get_block_t get_block);
> int mpage_writepages(struct address_space *mapping,
> - struct writeback_control *wbc, get_block_t get_block);
> -int mpage_writepage(struct page *page, get_block_t *get_block,
> - struct writeback_control *wbc);
> + struct writeback_control *wbc, get_blocks_t get_blocks);
> +int mpage_writepage(struct page *page, get_blocks_t *get_blocks,
> + struct writeback_control *wbc, writepage_t writepage);
> int __mpage_writepages(struct address_space *mapping,
> - struct writeback_control *wbc, get_block_t get_block,
> + struct writeback_control *wbc, get_blocks_t get_blocks,
> writepage_t writepage);
>
> static inline int
> diff -urp -X dontdiff linux-2.6.12-rc3/include/linux/pagemap.h linux-2.6.12-rc3-getblocks/include/linux/pagemap.h
> --- linux-2.6.12-rc3/include/linux/pagemap.h 2005-04-21 05:33:16.000000000 +0530
> +++ linux-2.6.12-rc3-getblocks/include/linux/pagemap.h 2005-04-22 15:08:33.000000000 +0530
> @@ -73,7 +73,8 @@ extern struct page * find_or_create_page
> unsigned find_get_pages(struct address_space *mapping, pgoff_t start,
> unsigned int nr_pages, struct page **pages);
> unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index,
> - int tag, unsigned int nr_pages, struct page **pages);
> + int tag, unsigned int nr_pages, struct page **pages,
> + int contig);
>
> /*
> * Returns locked page at given index in given cache, creating it if needed.
> diff -urp -X dontdiff linux-2.6.12-rc3/include/linux/pagevec.h linux-2.6.12-rc3-getblocks/include/linux/pagevec.h
> --- linux-2.6.12-rc3/include/linux/pagevec.h 2005-04-21 05:33:16.000000000 +0530
> +++ linux-2.6.12-rc3-getblocks/include/linux/pagevec.h 2005-04-22 15:08:33.000000000 +0530
> @@ -28,6 +28,9 @@ unsigned pagevec_lookup(struct pagevec *
> unsigned pagevec_lookup_tag(struct pagevec *pvec,
> struct address_space *mapping, pgoff_t *index, int tag,
> unsigned nr_pages);
> +unsigned pagevec_contig_lookup_tag(struct pagevec *pvec,
> + struct address_space *mapping, pgoff_t *index, int tag,
> + unsigned nr_pages);
>
> static inline void pagevec_init(struct pagevec *pvec, int cold)
> {
> diff -urp -X dontdiff linux-2.6.12-rc3/include/linux/radix-tree.h linux-2.6.12-rc3-getblocks/include/linux/radix-tree.h
> --- linux-2.6.12-rc3/include/linux/radix-tree.h 2005-04-21 05:33:16.000000000 +0530
> +++ linux-2.6.12-rc3-getblocks/include/linux/radix-tree.h 2005-04-22 15:08:33.000000000 +0530
> @@ -59,8 +59,18 @@ void *radix_tree_tag_clear(struct radix_
> int radix_tree_tag_get(struct radix_tree_root *root,
> unsigned long index, int tag);
> unsigned int
> -radix_tree_gang_lookup_tag(struct radix_tree_root *root, void **results,
> - unsigned long first_index, unsigned int max_items, int tag);
> +__radix_tree_gang_lookup_tag(struct radix_tree_root *root, void **results,
> + unsigned long first_index, unsigned int max_items, int tag,
> + int contig);
> +
> +static inline unsigned int radix_tree_gang_lookup_tag(struct radix_tree_root
> + *root, void **results, unsigned long first_index,
> + unsigned int max_items, int tag)
> +{
> + return __radix_tree_gang_lookup_tag(root, results, first_index,
> + max_items, tag, 0);
> +}
> +
> int radix_tree_tagged(struct radix_tree_root *root, int tag);
>
> static inline void radix_tree_preload_end(void)
> diff -urp -X dontdiff linux-2.6.12-rc3/lib/radix-tree.c linux-2.6.12-rc3-getblocks/lib/radix-tree.c
> --- linux-2.6.12-rc3/lib/radix-tree.c 2005-04-21 05:33:16.000000000 +0530
> +++ linux-2.6.12-rc3-getblocks/lib/radix-tree.c 2005-04-22 16:34:29.000000000 +0530
> @@ -557,12 +557,13 @@ EXPORT_SYMBOL(radix_tree_gang_lookup);
> */
> static unsigned int
> __lookup_tag(struct radix_tree_root *root, void **results, unsigned long index,
> - unsigned int max_items, unsigned long *next_index, int tag)
> + unsigned int max_items, unsigned long *next_index, int tag, int contig)
> {
> unsigned int nr_found = 0;
> unsigned int shift;
> unsigned int height = root->height;
> struct radix_tree_node *slot;
> + unsigned long cindex = (contig && (*next_index)) ? *next_index : -1;
>
> shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
> slot = root->rnode;
> @@ -575,6 +576,11 @@ __lookup_tag(struct radix_tree_root *roo
> BUG_ON(slot->slots[i] == NULL);
> break;
> }
> + if (contig && index >= cindex) {
> + /* break in contiguity */
> + index = 0;
> + goto out;
> + }
> index &= ~((1UL << shift) - 1);
> index += 1UL << shift;
> if (index == 0)
> @@ -593,6 +599,10 @@ __lookup_tag(struct radix_tree_root *roo
> results[nr_found++] = slot->slots[j];
> if (nr_found == max_items)
> goto out;
> + } else if (contig && nr_found) {
> + /* break in contiguity */
> + index = 0;
> + goto out;
> }
> }
> }
> @@ -618,29 +628,32 @@ out:
> * returns the number of items which were placed at *@results.
> */
> unsigned int
> -radix_tree_gang_lookup_tag(struct radix_tree_root *root, void **results,
> - unsigned long first_index, unsigned int max_items, int tag)
> +__radix_tree_gang_lookup_tag(struct radix_tree_root *root, void **results,
> + unsigned long first_index, unsigned int max_items, int tag,
> + int contig)
> {
> const unsigned long max_index = radix_tree_maxindex(root->height);
> unsigned long cur_index = first_index;
> + unsigned long next_index = 0; /* Index of next contiguous search */
> unsigned int ret = 0;
>
> while (ret < max_items) {
> unsigned int nr_found;
> - unsigned long next_index; /* Index of next search */
>
> if (cur_index > max_index)
> break;
> nr_found = __lookup_tag(root, results + ret, cur_index,
> - max_items - ret, &next_index, tag);
> + max_items - ret, &next_index, tag, contig);
> ret += nr_found;
> if (next_index == 0)
> break;
> cur_index = next_index;
> + if (!nr_found)
> + next_index = 0;
> }
> return ret;
> }
> -EXPORT_SYMBOL(radix_tree_gang_lookup_tag);
> +EXPORT_SYMBOL(__radix_tree_gang_lookup_tag);
>
> /**
> * radix_tree_delete - delete an item from a radix tree
> diff -urp -X dontdiff linux-2.6.12-rc3/mm/filemap.c linux-2.6.12-rc3-getblocks/mm/filemap.c
> --- linux-2.6.12-rc3/mm/filemap.c 2005-04-21 05:33:16.000000000 +0530
> +++ linux-2.6.12-rc3-getblocks/mm/filemap.c 2005-04-22 16:20:30.000000000 +0530
> @@ -635,16 +635,19 @@ unsigned find_get_pages(struct address_s
> /*
> * Like find_get_pages, except we only return pages which are tagged with
> * `tag'. We update *index to index the next page for the traversal.
> + * If 'contig' is 1, then we return only pages which are contiguous in the
> + * file.
> */
> unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index,
> - int tag, unsigned int nr_pages, struct page **pages)
> + int tag, unsigned int nr_pages, struct page **pages,
> + int contig)
> {
> unsigned int i;
> unsigned int ret;
>
> read_lock_irq(&mapping->tree_lock);
> - ret = radix_tree_gang_lookup_tag(&mapping->page_tree,
> - (void **)pages, *index, nr_pages, tag);
> + ret = __radix_tree_gang_lookup_tag(&mapping->page_tree,
> + (void **)pages, *index, nr_pages, tag, contig);
> for (i = 0; i < ret; i++)
> page_cache_get(pages[i]);
> if (ret)
> diff -urp -X dontdiff linux-2.6.12-rc3/mm/swap.c linux-2.6.12-rc3-getblocks/mm/swap.c
> --- linux-2.6.12-rc3/mm/swap.c 2005-04-21 05:33:16.000000000 +0530
> +++ linux-2.6.12-rc3-getblocks/mm/swap.c 2005-04-22 15:08:33.000000000 +0530
> @@ -384,7 +384,16 @@ unsigned pagevec_lookup_tag(struct pagev
> pgoff_t *index, int tag, unsigned nr_pages)
> {
> pvec->nr = find_get_pages_tag(mapping, index, tag,
> - nr_pages, pvec->pages);
> + nr_pages, pvec->pages, 0);
> + return pagevec_count(pvec);
> +}
> +
> +unsigned int
> +pagevec_contig_lookup_tag(struct pagevec *pvec, struct address_space *mapping,
> + pgoff_t *index, int tag, unsigned nr_pages)
> +{
> + pvec->nr = find_get_pages_tag(mapping, index, tag,
> + nr_pages, pvec->pages, 1);
> return pagevec_count(pvec);
> }
>
> -
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