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From: "Theodore Ts'o" <tytso@mit.edu>
To: Linux Filesystem Development List <linux-fsdevel@vger.kernel.org>
Cc: Ext4 Developers List <linux-ext4@vger.kernel.org>,
	linux-f2fs-devel@lists.sourceforge.net,
	"Theodore Ts'o" <tytso@mit.edu>,
	Eric Biggers <ebiggers@kernel.org>
Subject: [PATCH] writeback: avoid double-writing the inode on a lazytime expiration
Date: Fri,  6 Mar 2020 21:00:43 -0500	[thread overview]
Message-ID: <20200307020043.60118-1-tytso@mit.edu> (raw)
In-Reply-To: <20200306004555.GB225345@gmail.com>

In the case that an inode has dirty timestamp for longer than the
lazytime expiration timeout (or if all such inodes are being flushed
out due to a sync or syncfs system call), we need to inform the file
system that the inode is dirty so that the inode's timestamps can be
copied out to the on-disk data structures.  That's because if the file
system supports lazytime, it will have ignored the dirty_inode(inode,
I_DIRTY_TIME) notification when the timestamp was modified in memory.q

Previously, this was accomplished by calling mark_inode_dirty_sync(),
but that has the unfortunate side effect of also putting the inode the
writeback list, and that's not necessary in this case, since we will
immediately call write_inode() afterwards.

Eric Biggers noticed that this was causing problems for fscrypt after
the key was removed[1].

[1] https://lore.kernel.org/r/20200306004555.GB225345@gmail.com

Reported-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
---
 fs/fs-writeback.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 76ac9c7d32ec..32101349ba97 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -1504,8 +1504,9 @@ __writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
 
 	spin_unlock(&inode->i_lock);
 
-	if (dirty & I_DIRTY_TIME)
-		mark_inode_dirty_sync(inode);
+	/* This was a lazytime expiration; we need to tell the file system */
+	if (dirty & I_DIRTY_TIME_EXPIRED && inode->i_sb->s_op->dirty_inode)
+		inode->i_sb->s_op->dirty_inode(inode, I_DIRTY_TIME_EXPIRED);
 	/* Don't write the inode if only I_DIRTY_PAGES was set */
 	if (dirty & ~I_DIRTY_PAGES) {
 		int err = write_inode(inode, wbc);
-- 
2.24.1


WARNING: multiple messages have this Message-ID
From: "Theodore Ts'o" <tytso@mit.edu>
To: Linux Filesystem Development List <linux-fsdevel@vger.kernel.org>
Cc: Eric Biggers <ebiggers@kernel.org>,
	Ext4 Developers List <linux-ext4@vger.kernel.org>,
	Theodore Ts'o <tytso@mit.edu>,
	linux-f2fs-devel@lists.sourceforge.net
Subject: [f2fs-dev] [PATCH] writeback: avoid double-writing the inode on a lazytime expiration
Date: Fri,  6 Mar 2020 21:00:43 -0500	[thread overview]
Message-ID: <20200307020043.60118-1-tytso@mit.edu> (raw)
In-Reply-To: <20200306004555.GB225345@gmail.com>

In the case that an inode has dirty timestamp for longer than the
lazytime expiration timeout (or if all such inodes are being flushed
out due to a sync or syncfs system call), we need to inform the file
system that the inode is dirty so that the inode's timestamps can be
copied out to the on-disk data structures.  That's because if the file
system supports lazytime, it will have ignored the dirty_inode(inode,
I_DIRTY_TIME) notification when the timestamp was modified in memory.q

Previously, this was accomplished by calling mark_inode_dirty_sync(),
but that has the unfortunate side effect of also putting the inode the
writeback list, and that's not necessary in this case, since we will
immediately call write_inode() afterwards.

Eric Biggers noticed that this was causing problems for fscrypt after
the key was removed[1].

[1] https://lore.kernel.org/r/20200306004555.GB225345@gmail.com

Reported-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
---
 fs/fs-writeback.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 76ac9c7d32ec..32101349ba97 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -1504,8 +1504,9 @@ __writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
 
 	spin_unlock(&inode->i_lock);
 
-	if (dirty & I_DIRTY_TIME)
-		mark_inode_dirty_sync(inode);
+	/* This was a lazytime expiration; we need to tell the file system */
+	if (dirty & I_DIRTY_TIME_EXPIRED && inode->i_sb->s_op->dirty_inode)
+		inode->i_sb->s_op->dirty_inode(inode, I_DIRTY_TIME_EXPIRED);
 	/* Don't write the inode if only I_DIRTY_PAGES was set */
 	if (dirty & ~I_DIRTY_PAGES) {
 		int err = write_inode(inode, wbc);
-- 
2.24.1



_______________________________________________
Linux-f2fs-devel mailing list
Linux-f2fs-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel

  reply	other threads:[~2020-03-07  2:01 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-06  0:45 lazytime causing inodes to remain dirty after sync? Eric Biggers
2020-03-06  0:45 ` [f2fs-dev] " Eric Biggers
2020-03-07  2:00 ` Theodore Ts'o [this message]
2020-03-07  2:00   ` [f2fs-dev] [PATCH] writeback: avoid double-writing the inode on a lazytime expiration Theodore Ts'o
2020-03-11  3:20   ` Eric Biggers
2020-03-11  3:20     ` [f2fs-dev] " Eric Biggers
2020-03-11 12:57     ` Theodore Y. Ts'o
2020-03-11 12:57       ` [f2fs-dev] " Theodore Y. Ts'o
2020-03-12  0:07       ` Dave Chinner
2020-03-12  0:07         ` [f2fs-dev] " Dave Chinner
2020-03-12 14:34         ` Christoph Hellwig
2020-03-12 14:34           ` [f2fs-dev] " Christoph Hellwig
2020-03-12 22:39           ` Dave Chinner
2020-03-12 22:39             ` [f2fs-dev] " Dave Chinner
2020-03-20  2:46           ` Theodore Y. Ts'o
2020-03-20  2:46             ` [f2fs-dev] " Theodore Y. Ts'o
2020-03-20  2:52             ` [PATCH 1/2] " Theodore Ts'o
2020-03-20  2:52               ` [f2fs-dev] " Theodore Ts'o
2020-03-20  2:52               ` [PATCH 2/2] writeback, xfs: call dirty_inode() with I_DIRTY_TIME_EXPIRED when appropriate Theodore Ts'o
2020-03-20  2:52                 ` [f2fs-dev] " Theodore Ts'o
2020-03-23 17:58                 ` Theodore Y. Ts'o
2020-03-23 17:58                   ` [f2fs-dev] " Theodore Y. Ts'o
2020-03-24  8:37                   ` Christoph Hellwig
2020-03-24  8:37                     ` [f2fs-dev] " Christoph Hellwig
2020-03-24 18:43                     ` Theodore Y. Ts'o
2020-03-24 18:43                       ` [f2fs-dev] " Theodore Y. Ts'o
2020-03-25  9:20               ` [PATCH 1/2] writeback: avoid double-writing the inode on a lazytime expiration Christoph Hellwig
2020-03-25  9:20                 ` [f2fs-dev] " Christoph Hellwig
2020-03-25 15:21                 ` Theodore Y. Ts'o
2020-03-25 15:21                   ` [f2fs-dev] " Theodore Y. Ts'o
2020-03-25 15:47                   ` Darrick J. Wong
2020-03-25 15:47                     ` [f2fs-dev] " Darrick J. Wong
2020-03-11 23:54     ` [PATCH] " Dave Chinner
2020-03-11 23:54       ` [f2fs-dev] " Dave Chinner

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