FAILED: patch "[PATCH] btrfs: fix error handling in btrfs_dev_replace_start" failed to apply to 4.14-stable tree

FAILED: patch "[PATCH] btrfs: fix error handling in btrfs_dev_replace_start" failed to apply to 4.14-stable tree

[gregkh]

The patch below does not apply to the 4.14-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

>From 5c06147128fbbdf7a84232c5f0d808f53153defe Mon Sep 17 00:00:00 2001
From: Jeff Mahoney <jeffm@suse.com>
Date: Thu, 6 Sep 2018 15:52:17 -0400
Subject: [PATCH] btrfs: fix error handling in btrfs_dev_replace_start

When we fail to start a transaction in btrfs_dev_replace_start, we leave
dev_replace->replace_start set to STARTED but clear ->srcdev and
->tgtdev.  Later, that can result in an Oops in
btrfs_dev_replace_progress when having state set to STARTED or SUSPENDED
implies that ->srcdev is valid.

Also fix error handling when the state is already STARTED or SUSPENDED
while starting.  That, too, will clear ->srcdev and ->tgtdev even though
it doesn't own them.  This should be an impossible case to hit since we
should be protected by the BTRFS_FS_EXCL_OP bit being set.  Let's add an
ASSERT there while we're at it.

Fixes: e93c89c1aaaaa (Btrfs: add new sources for device replace code)
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/dev-replace.c b/fs/btrfs/dev-replace.c
index 4e2b67d06305..ff01740158aa 100644
--- a/fs/btrfs/dev-replace.c
+++ b/fs/btrfs/dev-replace.c
@@ -440,6 +440,7 @@ int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info,
 		break;
 	case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 	case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
+		ASSERT(0);
 		ret = BTRFS_IOCTL_DEV_REPLACE_RESULT_ALREADY_STARTED;
 		goto leave;
 	}
@@ -482,6 +483,10 @@ int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info,
 	if (IS_ERR(trans)) {
 		ret = PTR_ERR(trans);
 		btrfs_dev_replace_write_lock(dev_replace);
+		dev_replace->replace_state =
+			BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED;
+		dev_replace->srcdev = NULL;
+		dev_replace->tgtdev = NULL;
 		goto leave;
 	}
 
@@ -503,8 +508,6 @@ int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info,
 	return ret;
 
 leave:
-	dev_replace->srcdev = NULL;
-	dev_replace->tgtdev = NULL;
 	btrfs_dev_replace_write_unlock(dev_replace);
 	btrfs_destroy_dev_replace_tgtdev(tgt_device);
 	return ret;

Re: FAILED: patch "[PATCH] btrfs: fix error handling in btrfs_dev_replace_start" failed to apply to 4.14-stable tree

[Sudip Mukherjee]

[-- Attachment #1: Type: text/plain, Size: 410 bytes --]

Hi Greg,

On Sun, Nov 11, 2018 at 12:10:46PM -0800, gregkh@linuxfoundation.org wrote:
> 
> The patch below does not apply to the 4.14-stable tree.
> If someone wants it applied there, or to any other stable or longterm
> tree, then please email the backport, including the original git commit
> id to <stable@vger.kernel.org>.

The attached backported patch should apply to 4.14-stable tree.

--
Regards
Sudip

[-- Attachment #2: 0001-btrfs-fix-error-handling-in-btrfs_dev_replace_start.patch --]
[-- Type: text/x-diff, Size: 2335 bytes --]

From 96e512087f6515984931ec3c7c3e80b9fbc0cfbb Mon Sep 17 00:00:00 2001
From: Jeff Mahoney <jeffm@suse.com>
Date: Thu, 6 Sep 2018 15:52:17 -0400
Subject: [PATCH] btrfs: fix error handling in btrfs_dev_replace_start

commit 5c06147128fbbdf7a84232c5f0d808f53153defe upstream

When we fail to start a transaction in btrfs_dev_replace_start, we leave
dev_replace->replace_start set to STARTED but clear ->srcdev and
->tgtdev.  Later, that can result in an Oops in
btrfs_dev_replace_progress when having state set to STARTED or SUSPENDED
implies that ->srcdev is valid.

Also fix error handling when the state is already STARTED or SUSPENDED
while starting.  That, too, will clear ->srcdev and ->tgtdev even though
it doesn't own them.  This should be an impossible case to hit since we
should be protected by the BTRFS_FS_EXCL_OP bit being set.  Let's add an
ASSERT there while we're at it.

Fixes: e93c89c1aaaaa (Btrfs: add new sources for device replace code)
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
---
 fs/btrfs/dev-replace.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/fs/btrfs/dev-replace.c b/fs/btrfs/dev-replace.c
index dd80a1bdf9e2..68362eddaea2 100644
--- a/fs/btrfs/dev-replace.c
+++ b/fs/btrfs/dev-replace.c
@@ -351,6 +351,7 @@ int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info,
 		break;
 	case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 	case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
+		ASSERT(0);
 		ret = BTRFS_IOCTL_DEV_REPLACE_RESULT_ALREADY_STARTED;
 		goto leave;
 	}
@@ -395,6 +396,10 @@ int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info,
 	if (IS_ERR(trans)) {
 		ret = PTR_ERR(trans);
 		btrfs_dev_replace_lock(dev_replace, 1);
+		dev_replace->replace_state =
+			BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED;
+		dev_replace->srcdev = NULL;
+		dev_replace->tgtdev = NULL;
 		goto leave;
 	}
 
@@ -416,8 +421,6 @@ int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info,
 	return ret;
 
 leave:
-	dev_replace->srcdev = NULL;
-	dev_replace->tgtdev = NULL;
 	btrfs_dev_replace_unlock(dev_replace, 1);
 	btrfs_destroy_dev_replace_tgtdev(fs_info, tgt_device);
 	return ret;
-- 
2.11.0

Re: FAILED: patch "[PATCH] btrfs: fix error handling in btrfs_dev_replace_start" failed to apply to 4.14-stable tree

[Greg KH]

On Mon, Jan 28, 2019 at 09:45:15PM +0000, Sudip Mukherjee wrote:
> Hi Greg,
> 
> On Sun, Nov 11, 2018 at 12:10:46PM -0800, gregkh@linuxfoundation.org wrote:
> > 
> > The patch below does not apply to the 4.14-stable tree.
> > If someone wants it applied there, or to any other stable or longterm
> > tree, then please email the backport, including the original git commit
> > id to <stable@vger.kernel.org>.
> 
> The attached backported patch should apply to 4.14-stable tree.

Now applied, thanks.

greg k-h