Re: [PATCH] btrfs: zoned: fix linked list corruption after log root tree allocation failure

[David Sterba]

On Thu, Mar 11, 2021 at 03:13:30PM +, fdman...@kernel.org wrote:
> From: Filipe Manana 
> 
> When using a zoned filesystem, while syncing the log, if we fail to
> allocate the root node for the log root tree, we are not removing the
> log context we allocated on stack from the list of log contextes of the
> log root tree. This means after the return from btrfs_sync_log() we get
> a corrupted linked list.
> 
> Fix this by allocating the node before adding our stack allocated context
> to the list of log contextes of the log root tree.
> 
> Fixes: 3ddebf27fcd3a9 ("btrfs: zoned: reorder log node allocation on zoned 
> filesystem")
> Signed-off-by: Filipe Manana 

Added to misc-next, thanks.

Re: [PATCH] btrfs: zoned: fix linked list corruption after log root tree allocation failure

[Naohiro Aota]

Looks good to me. Thanks.
Reviewed-by: Naohiro Aota 

On Thu, Mar 11, 2021 at 03:13:30PM +, fdman...@kernel.org wrote:
> From: Filipe Manana 
> 
> When using a zoned filesystem, while syncing the log, if we fail to
> allocate the root node for the log root tree, we are not removing the
> log context we allocated on stack from the list of log contextes of the
> log root tree. This means after the return from btrfs_sync_log() we get
> a corrupted linked list.
> 
> Fix this by allocating the node before adding our stack allocated context
> to the list of log contextes of the log root tree.
> 
> Fixes: 3ddebf27fcd3a9 ("btrfs: zoned: reorder log node allocation on zoned 
> filesystem")
> Signed-off-by: Filipe Manana 
> ---
>  fs/btrfs/tree-log.c | 8 
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
> index 2f1acc9aea9e..92a368627791 100644
> --- a/fs/btrfs/tree-log.c
> +++ b/fs/btrfs/tree-log.c
> @@ -3169,10 +3169,6 @@ int btrfs_sync_log(struct btrfs_trans_handle *trans,
>  
>   mutex_lock(&log_root_tree->log_mutex);
>  
> - index2 = log_root_tree->log_transid % 2;
> - list_add_tail(&root_log_ctx.list, &log_root_tree->log_ctxs[index2]);
> - root_log_ctx.log_transid = log_root_tree->log_transid;
> -
>   if (btrfs_is_zoned(fs_info)) {
>   if (!log_root_tree->node) {
>   ret = btrfs_alloc_log_tree_node(trans, log_root_tree);
> @@ -3183,6 +3179,10 @@ int btrfs_sync_log(struct btrfs_trans_handle *trans,
>   }
>   }
>  
> + index2 = log_root_tree->log_transid % 2;
> + list_add_tail(&root_log_ctx.list, &log_root_tree->log_ctxs[index2]);
> + root_log_ctx.log_transid = log_root_tree->log_transid;
> +
>   /*
>* Now we are safe to update the log_root_tree because we're under the
>* log_mutex, and we're a current writer so we're holding the commit
> -- 
> 2.28.0
> 

Re: [PATCH] btrfs: zoned: fix linked list corruption after log root tree allocation failure

[Johannes Thumshirn]

Looks good, Thanks!
Reviewed-by: Johannes Thumshirn 

[PATCH] btrfs: zoned: fix linked list corruption after log root tree allocation failure

[fdmanana]

From: Filipe Manana 

When using a zoned filesystem, while syncing the log, if we fail to
allocate the root node for the log root tree, we are not removing the
log context we allocated on stack from the list of log contextes of the
log root tree. This means after the return from btrfs_sync_log() we get
a corrupted linked list.

Fix this by allocating the node before adding our stack allocated context
to the list of log contextes of the log root tree.

Fixes: 3ddebf27fcd3a9 ("btrfs: zoned: reorder log node allocation on zoned 
filesystem")
Signed-off-by: Filipe Manana 
---
 fs/btrfs/tree-log.c | 8 
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index 2f1acc9aea9e..92a368627791 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -3169,10 +3169,6 @@ int btrfs_sync_log(struct btrfs_trans_handle *trans,
 
mutex_lock(&log_root_tree->log_mutex);
 
-   index2 = log_root_tree->log_transid % 2;
-   list_add_tail(&root_log_ctx.list, &log_root_tree->log_ctxs[index2]);
-   root_log_ctx.log_transid = log_root_tree->log_transid;
-
if (btrfs_is_zoned(fs_info)) {
if (!log_root_tree->node) {
ret = btrfs_alloc_log_tree_node(trans, log_root_tree);
@@ -3183,6 +3179,10 @@ int btrfs_sync_log(struct btrfs_trans_handle *trans,
}
}
 
+   index2 = log_root_tree->log_transid % 2;
+   list_add_tail(&root_log_ctx.list, &log_root_tree->log_ctxs[index2]);
+   root_log_ctx.log_transid = log_root_tree->log_transid;
+
/*
 * Now we are safe to update the log_root_tree because we're under the
 * log_mutex, and we're a current writer so we're holding the commit
-- 
2.28.0