This is a note to let you know that I've just added the patch titled
ext4: Fix file fragmentation during large file write.
to the 2.6.27-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
ext4-fix-file-fragmentation-during-large-file-write.patch
and it can be found in the queue-2.6.27 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxx> know about it.
>From dev@xxxxxxxxxxxxxx Fri Jun 25 15:33:09 2010
From: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
Date: Fri, 28 May 2010 14:26:57 -0500
Subject: ext4: Fix file fragmentation during large file write.
Cc: "Jayson R. King" <dev@xxxxxxxxxxxxxx>, Theodore Ts'o <tytso@xxxxxxx>, "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxxxxxxx>, Dave Chinner <david@xxxxxxxxxxxxx>, Ext4 Developers List <linux-ext4@xxxxxxxxxxxxxxx>, Kay Diederichs <Kay.Diederichs@xxxxxxxxxxxxxxx>
Message-ID: <4C001901.1070207@xxxxxxxxxxxxxx>
From: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
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@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Theodore Ts'o <tytso@xxxxxxx>
[dev@xxxxxxxxxxxxxx: 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@xxxxxxxxxxxxxx: Use of wbc->no_nrwrite_index_update was dropped, since write_cache_pages_da() implies it.]
Signed-off-by: Jayson R. King <dev@xxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
---
fs/ext4/inode.c | 79 ++++++++++++++++++++++++++++++++------------------------
1 file changed, 46 insertions(+), 33 deletions(-)
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -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 (!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;
}
+ 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);
+
+ /* 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;
}
Patches currently in stable-queue which might be from aneesh.kumar@xxxxxxxxxxxxxxxxxx are
queue-2.6.27/ext4-fix-file-fragmentation-during-large-file-write.patch
queue-2.6.27/ext4-use-our-own-write_cache_pages.patch
queue-2.6.27/ext4-implement-range_cyclic-in-ext4_da_writepages-instead-of-write_cache_pages.patch
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