[PATCH] ext4: fix inode tree inconsistency caused by ENOMEM

[PATCH] ext4: fix inode tree inconsistency caused by ENOMEM

[zhanchengbin]

If ENOMEM fails when the extent is splitting, we need to restore the length
of the split extent.
In the ext4_split_extent_at function, only in ext4_ext_create_new_leaf will
it alloc memory and change the shape of the extent tree,even if an ENOMEM
is returned at this time, the extent tree is still self-consistent, Just
restore the split extent lens in the function ext4_split_extent_at.

ext4_split_extent_at
 ext4_ext_insert_extent
  ext4_ext_create_new_leaf
   1)ext4_ext_split
     ext4_find_extent
   2)ext4_ext_grow_indepth
     ext4_find_extent

Signed-off-by: zhanchengbin <zhanchengbin1@huawei.com>
---
 Another solution is to add the __GFP_NOFAIL flag when allocating memory.

 fs/ext4/extents.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 9de1c9d1a13d..3559ea6b0781 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -3251,7 +3251,7 @@ static int ext4_split_extent_at(handle_t *handle,
 		ext4_ext_mark_unwritten(ex2);
 
 	err = ext4_ext_insert_extent(handle, inode, ppath, &newex, flags);
-	if (err != -ENOSPC && err != -EDQUOT)
+	if (err != -ENOSPC && err != -EDQUOT && err != -ENOMEM)
 		goto out;
 
 	if (EXT4_EXT_MAY_ZEROOUT & split_flag) {
-- 
2.31.1

Re: [PATCH] ext4: fix inode tree inconsistency caused by ENOMEM

[Jan Kara]

On Tue 03-01-23 10:28:12, zhanchengbin wrote:
> If ENOMEM fails when the extent is splitting, we need to restore the length
> of the split extent.
> In the ext4_split_extent_at function, only in ext4_ext_create_new_leaf will
> it alloc memory and change the shape of the extent tree,even if an ENOMEM
> is returned at this time, the extent tree is still self-consistent, Just
> restore the split extent lens in the function ext4_split_extent_at.
> 
> ext4_split_extent_at
>  ext4_ext_insert_extent
>   ext4_ext_create_new_leaf
>    1)ext4_ext_split
>      ext4_find_extent
>    2)ext4_ext_grow_indepth
>      ext4_find_extent
> 
> Signed-off-by: zhanchengbin <zhanchengbin1@huawei.com>

Yeah that should work. Feel free to add:

Reviewed-by: Jan Kara <jack@suse.cz>

								Honza

> ---
>  Another solution is to add the __GFP_NOFAIL flag when allocating memory.
> 
>  fs/ext4/extents.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
> index 9de1c9d1a13d..3559ea6b0781 100644
> --- a/fs/ext4/extents.c
> +++ b/fs/ext4/extents.c
> @@ -3251,7 +3251,7 @@ static int ext4_split_extent_at(handle_t *handle,
>  		ext4_ext_mark_unwritten(ex2);
>  
>  	err = ext4_ext_insert_extent(handle, inode, ppath, &newex, flags);
> -	if (err != -ENOSPC && err != -EDQUOT)
> +	if (err != -ENOSPC && err != -EDQUOT && err != -ENOMEM)
>  		goto out;
>  
>  	if (EXT4_EXT_MAY_ZEROOUT & split_flag) {
> -- 
> 2.31.1
> 
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR

Re: [PATCH] ext4: fix inode tree inconsistency caused by ENOMEM

[Theodore Ts'o]

On Tue, 3 Jan 2023 10:28:12 +0800, zhanchengbin wrote:
> If ENOMEM fails when the extent is splitting, we need to restore the length
> of the split extent.
> In the ext4_split_extent_at function, only in ext4_ext_create_new_leaf will
> it alloc memory and change the shape of the extent tree,even if an ENOMEM
> is returned at this time, the extent tree is still self-consistent, Just
> restore the split extent lens in the function ext4_split_extent_at.
> 
> [...]

Applied, thanks!

[1/1] ext4: fix inode tree inconsistency caused by ENOMEM
      commit: 3f5424790d4377839093b68c12b130077a4e4510

Best regards,
-- 
Theodore Ts'o <tytso@mit.edu>