linux-ext4 - [PATCH 24/29] ext4: Remove wait for unwritten extent conversion from ext4_ext

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <1365456754-29373-25-git-send-email-jack@suse.cz>
Date:	Mon,  8 Apr 2013 23:32:29 +0200
From:	Jan Kara <jack@...e.cz>
To:	Ted Tso <tytso@....edu>
Cc:	linux-ext4@...r.kernel.org, Jan Kara <jack@...e.cz>
Subject: [PATCH 24/29] ext4: Remove wait for unwritten extent conversion from ext4_ext_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_ext_truncate() anymore.

Signed-off-by: Jan Kara <jack@...e.cz>
---
 fs/ext4/extents.c |    6 ------
 fs/ext4/page-io.c |    9 ++++++++-
 2 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index ae22735..ca4ff71 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -4256,12 +4256,6 @@ void ext4_ext_truncate(struct inode *inode)
 	int err = 0;
 
 	/*
-	 * finish any pending end_io work so we won't run the risk of
-	 * converting any truncated blocks to initialized later
-	 */
-	ext4_flush_unwritten_io(inode);
-
-	/*
 	 * probably first extent we're gonna free will be last in block
 	 */
 	err = ext4_writepage_trans_blocks(inode);
diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c
index 2967794..2f0b943 100644
--- a/fs/ext4/page-io.c
+++ b/fs/ext4/page-io.c
@@ -145,7 +145,14 @@ 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;
-- 
1.7.1

--
To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html