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authorXiaoguang Wang <xiaoguang.wang@linux.alibaba.com>2019-02-10 23:53:21 -0500
committerTheodore Ts'o <tytso@mit.edu>2019-02-10 23:53:21 -0500
commita297b2fcee461e40df763e179cbbfba5a9e572d2 (patch)
treeb15dfad165f70a7b360b2d94676e2842f9d9cf0b /fs/ext4
parent16e08b14a4550bb167c48e918b26ef0d4980e9d1 (diff)
downloadlinux-a297b2fcee461e40df763e179cbbfba5a9e572d2.tar.bz2
ext4: unlock unused_pages timely when doing writeback
In mpage_add_bh_to_extent(), when accumulated extents length is greater than MAX_WRITEPAGES_EXTENT_LEN or buffer head's b_stat is not equal, we will not continue to search unmapped area for this page, but note this page is locked, and will only be unlocked in mpage_release_unused_pages() after ext4_io_submit, if io also is throttled by blk-throttle or similar io qos, we will hold this page locked for a while, it's unnecessary. I think the best fix is to refactor mpage_add_bh_to_extent() to let it return some hints whether to unlock this page, but given that we will improve dioread_nolock later, we can let it done later, so currently the simple fix would just call mpage_release_unused_pages() before ext4_io_submit(). Signed-off-by: Xiaoguang Wang <xiaoguang.wang@linux.alibaba.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Diffstat (limited to 'fs/ext4')
-rw-r--r--fs/ext4/inode.c9
1 files changed, 5 insertions, 4 deletions
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index dd4641f3cdb9..9c3402ec85bc 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -2829,12 +2829,12 @@ retry:
goto unplug;
}
ret = mpage_prepare_extent_to_map(&mpd);
+ /* Unlock pages we didn't use */
+ mpage_release_unused_pages(&mpd, false);
/* Submit prepared bio */
ext4_io_submit(&mpd.io_submit);
ext4_put_io_end_defer(mpd.io_submit.io_end);
mpd.io_submit.io_end = NULL;
- /* Unlock pages we didn't use */
- mpage_release_unused_pages(&mpd, false);
if (ret < 0)
goto unplug;
@@ -2902,10 +2902,11 @@ retry:
handle = NULL;
mpd.do_map = 0;
}
- /* Submit prepared bio */
- ext4_io_submit(&mpd.io_submit);
/* Unlock pages we didn't use */
mpage_release_unused_pages(&mpd, give_up_on_write);
+ /* Submit prepared bio */
+ ext4_io_submit(&mpd.io_submit);
+
/*
* Drop our io_end reference we got from init. We have
* to be careful and use deferred io_end finishing if