lkml.org 
[lkml]   [2010]   [May]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Date
    From
    Subject[PATCH 2.6.27.y 2/3] ext4: Fix file fragmentation during large file write.
    From: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
    Date: Thu Oct 16 10:10:36 2008 -0400
    Subject: ext4: Fix file fragmentation during large file write.

    commit 22208dedbd7626e5fc4339c417f8d24cc21f79d7 upstream.

    The range_cyclic writeback mode uses the address_space writeback_index
    as the start index for writeback. With delayed allocation we were
    updating writeback_index wrongly resulting in highly fragmented file.
    This patch reduces the number of extents reduced from 4000 to 27 for a
    3GB file.

    Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
    Signed-off-by: Theodore Ts'o <tytso@mit.edu>
    [dev@jaysonking.com: Some changed lines from the original version of this patch were dropped, since they were rolled up with another cherry-picked patch applied to 2.6.27.y earlier.]
    [dev@jaysonking.com: Use of wbc->no_nrwrite_index_update was dropped, since write_cache_pages_da() implies it.]
    Signed-off-by: Jayson R. King <dev@jaysonking.com>

    ---
    fs/ext4/inode.c | 77 ++++++++++++++++++++++++++--------------------
    1 file changed, 45 insertions(+), 32 deletions(-)

    diff -udrNp linux-2.6.27.orig/fs/ext4/inode.c linux-2.6.27/fs/ext4/inode.c
    --- linux-2.6.27.orig/fs/ext4/inode.c 2010-05-28 12:52:08.450963139 -0500
    +++ linux-2.6.27/fs/ext4/inode.c 2010-05-28 12:52:18.258962978 -0500
    @@ -1721,7 +1721,11 @@ static int mpage_da_submit_io(struct mpa

    pages_skipped = mpd->wbc->pages_skipped;
    err = mapping->a_ops->writepage(page, mpd->wbc);
    - if (!err)
    + if (!err && (pages_skipped == mpd->wbc->pages_skipped))
    + /*
    + * have successfully written the page
    + * without skipping the same
    + */
    mpd->pages_written++;
    /*
    * In error case, we have to continue because
    @@ -2295,7 +2299,6 @@ static int mpage_da_writepages(struct ad
    struct writeback_control *wbc,
    struct mpage_da_data *mpd)
    {
    - long to_write;
    int ret;

    if (!mpd->get_block)
    @@ -2310,19 +2313,18 @@ static int mpage_da_writepages(struct ad
    mpd->pages_written = 0;
    mpd->retval = 0;

    - to_write = wbc->nr_to_write;
    -
    ret = write_cache_pages_da(mapping, wbc, mpd);
    -
    /*
    * Handle last extent of pages
    */
    if (!mpd->io_done && mpd->next_page != mpd->first_page) {
    if (mpage_da_map_blocks(mpd) == 0)
    mpage_da_submit_io(mpd);
    - }

    - wbc->nr_to_write = to_write - mpd->pages_written;
    + mpd->io_done = 1;
    + ret = MPAGE_DA_EXTENT_TAIL;
    + }
    + wbc->nr_to_write -= mpd->pages_written;
    return ret;
    }

    @@ -2567,11 +2569,13 @@ static int ext4_da_writepages_trans_bloc
    static int ext4_da_writepages(struct address_space *mapping,
    struct writeback_control *wbc)
    {
    + pgoff_t index;
    + int range_whole = 0;
    handle_t *handle = NULL;
    struct mpage_da_data mpd;
    struct inode *inode = mapping->host;
    + long pages_written = 0, pages_skipped;
    int needed_blocks, ret = 0, nr_to_writebump = 0;
    - long to_write, pages_skipped = 0;
    struct ext4_sb_info *sbi = EXT4_SB(mapping->host->i_sb);

    /*
    @@ -2605,16 +2609,20 @@ static int ext4_da_writepages(struct add
    nr_to_writebump = sbi->s_mb_stream_request - wbc->nr_to_write;
    wbc->nr_to_write = sbi->s_mb_stream_request;
    }
    + if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
    + range_whole = 1;

    -
    - pages_skipped = wbc->pages_skipped;
    + if (wbc->range_cyclic)
    + index = mapping->writeback_index;
    + else
    + index = wbc->range_start >> PAGE_CACHE_SHIFT;

    mpd.wbc = wbc;
    mpd.inode = mapping->host;

    -restart_loop:
    - to_write = wbc->nr_to_write;
    - while (!ret && to_write > 0) {
    + pages_skipped = wbc->pages_skipped;
    +
    + while (!ret && wbc->nr_to_write > 0) {

    /*
    * we insert one extent at a time. So we need
    @@ -2647,46 +2655,51 @@ restart_loop:
    goto out_writepages;
    }
    }
    - to_write -= wbc->nr_to_write;
    -
    mpd.get_block = ext4_da_get_block_write;
    ret = mpage_da_writepages(mapping, wbc, &mpd);

    ext4_journal_stop(handle);

    - if (mpd.retval == -ENOSPC)
    + if (mpd.retval == -ENOSPC) {
    + /* commit the transaction which would
    + * free blocks released in the transaction
    + * and try again
    + */
    jbd2_journal_force_commit_nested(sbi->s_journal);
    -
    - /* reset the retry count */
    - if (ret == MPAGE_DA_EXTENT_TAIL) {
    + wbc->pages_skipped = pages_skipped;
    + ret = 0;
    + } else if (ret == MPAGE_DA_EXTENT_TAIL) {
    /*
    * got one extent now try with
    * rest of the pages
    */
    - to_write += wbc->nr_to_write;
    + pages_written += mpd.pages_written;
    + wbc->pages_skipped = pages_skipped;
    ret = 0;
    - } else if (wbc->nr_to_write) {
    + } else if (wbc->nr_to_write)
    /*
    * There is no more writeout needed
    * or we requested for a noblocking writeout
    * and we found the device congested
    */
    - to_write += wbc->nr_to_write;
    break;
    - }
    - wbc->nr_to_write = to_write;
    }
    + if (pages_skipped != wbc->pages_skipped)
    + printk(KERN_EMERG "This should not happen leaving %s "
    + "with nr_to_write = %ld ret = %d\n",
    + __func__, wbc->nr_to_write, ret);

    - if (!wbc->range_cyclic && (pages_skipped != wbc->pages_skipped)) {
    - /* We skipped pages in this loop */
    - wbc->nr_to_write = to_write +
    - wbc->pages_skipped - pages_skipped;
    - wbc->pages_skipped = pages_skipped;
    - goto restart_loop;
    - }
    + /* Update index */
    + index += pages_written;
    + if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
    + /*
    + * set the writeback_index so that range_cyclic
    + * mode will write it back later
    + */
    + mapping->writeback_index = index;

    out_writepages:
    - wbc->nr_to_write = to_write - nr_to_writebump;
    + wbc->nr_to_write -= nr_to_writebump;
    return ret;
    }


    \
     
     \ /
      Last update: 2010-05-28 22:07    [W:0.037 / U:0.028 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site