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authorJan Kara <jack@suse.cz>2013-06-04 22:30:00 +0400
committerTheodore Ts'o <tytso@mit.edu>2013-06-04 22:30:00 +0400
commita115f749c14ee94e8b7bdbd203a5afdb1659156b (patch)
tree6977574e331f21d2fae2247e442a1f8f23560203 /fs/ext4/page-io.c
parente83403959fddb6d90e8c5e54bbce3110d0c82165 (diff)
downloadlinux-a115f749c14ee94e8b7bdbd203a5afdb1659156b.tar.xz
ext4: remove wait for unwritten extent conversion from ext4_truncate()
Since PageWriteback bit is now cleared after extents are converted from unwritten to written ones, we have full exclusion of writeback path from truncate (truncate_inode_pages() waits for PageWriteback bits to get cleared on all invalidated pages). Exclusion from DIO path is achieved by inode_dio_wait() call in ext4_setattr(). So there's no need to wait for extent convertion in ext4_truncate() anymore. Reviewed-by: Zheng Liu <wenqing.lz@taobao.com> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Diffstat (limited to 'fs/ext4/page-io.c')
-rw-r--r--fs/ext4/page-io.c9
1 files changed, 8 insertions, 1 deletions
diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c
index 755741c211a4..0f65561ab5a5 100644
--- a/fs/ext4/page-io.c
+++ b/fs/ext4/page-io.c
@@ -158,7 +158,14 @@ static void ext4_clear_io_unwritten_flag(ext4_io_end_t *io_end)
wake_up_all(ext4_ioend_wq(inode));
}
-/* check a range of space and convert unwritten extents to written. */
+/*
+ * Check a range of space and convert unwritten extents to written. Note that
+ * we are protected from truncate touching same part of extent tree by the
+ * fact that truncate code waits for all DIO to finish (thus exclusion from
+ * direct IO is achieved) and also waits for PageWriteback bits. Thus we
+ * cannot get to ext4_ext_truncate() before all IOs overlapping that range are
+ * completed (happens from ext4_free_ioend()).
+ */
static int ext4_end_io(ext4_io_end_t *io)
{
struct inode *inode = io->inode;