diff mbox series

[v4,1/3] ext4: fix incorrect calculate 'reserved' in '__es_remove_extent' when enable bigalloc feature

Message ID 20221208033426.1832460-2-yebin@huaweicloud.com
State New
Headers show
Series Fix two issues about bigalloc feature | expand

Commit Message

Ye Bin Dec. 8, 2022, 3:34 a.m. UTC 
From: Ye Bin <yebin10@huawei.com>

Syzbot report issue as follows:
EXT4-fs error (device loop0): ext4_validate_block_bitmap:398: comm rep:
	bg 0: block 5: invalid block bitmap
EXT4-fs (loop0): Delayed block allocation failed for inode 18 at logical
	offset 0 with max blocks 32 with error 28
EXT4-fs (loop0): This should not happen!! Data will be lost

EXT4-fs (loop0): Total free blocks count 0
EXT4-fs (loop0): Free/Dirty block details
EXT4-fs (loop0): free_blocks=0
EXT4-fs (loop0): dirty_blocks=32
EXT4-fs (loop0): Block reservation details
EXT4-fs (loop0): i_reserved_data_blocks=2
EXT4-fs (loop0): Inode 18 (00000000845cd634):
	i_reserved_data_blocks (1) not cleared!

Above issue happens as follows:
Assume:
sbi->s_cluster_ratio = 16
Step1:
Insert delay block [0, 31] -> ei->i_reserved_data_blocks=2
Step2:
ext4_writepages
  mpage_map_and_submit_extent -> return failed
  mpage_release_unused_pages -> to release [0, 30]
    ext4_es_remove_extent -> remove lblk=0 end=30
      __es_remove_extent -> len1=0 len2=31-30=1
 __es_remove_extent:
 ...
 if (len2 > 0) {
  ...
	  if (len1 > 0) {
		  ...
	  } else {
		es->es_lblk = end + 1;
		es->es_len = len2;
		...
	  }
  	if (count_reserved)
		count_rsvd(inode, lblk, ...);
	goto out; -> will return but didn't calculate 'reserved'
 ...
Step3:
ext4_destroy_inode -> trigger "i_reserved_data_blocks (1) not cleared!"

To solve above issue if 'len2>0' call 'get_rsvd()' before goto out.

Reported-by: syzbot+05a0f0ccab4a25626e38@syzkaller.appspotmail.com
Fixes: 8fcc3a580651 ("ext4: rework reserved cluster accounting when invalidating pages")
Signed-off-by: Ye Bin <yebin10@huawei.com>
---
 fs/ext4/extents_status.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

Comments

Eric Whitney Dec. 8, 2022, 11:01 p.m. UTC | #1 
* Ye Bin <yebin@huaweicloud.com>:
> From: Ye Bin <yebin10@huawei.com>
> 
> Syzbot report issue as follows:
> EXT4-fs error (device loop0): ext4_validate_block_bitmap:398: comm rep:
> 	bg 0: block 5: invalid block bitmap
> EXT4-fs (loop0): Delayed block allocation failed for inode 18 at logical
> 	offset 0 with max blocks 32 with error 28
> EXT4-fs (loop0): This should not happen!! Data will be lost
> 
> EXT4-fs (loop0): Total free blocks count 0
> EXT4-fs (loop0): Free/Dirty block details
> EXT4-fs (loop0): free_blocks=0
> EXT4-fs (loop0): dirty_blocks=32
> EXT4-fs (loop0): Block reservation details
> EXT4-fs (loop0): i_reserved_data_blocks=2
> EXT4-fs (loop0): Inode 18 (00000000845cd634):
> 	i_reserved_data_blocks (1) not cleared!
> 
> Above issue happens as follows:
> Assume:
> sbi->s_cluster_ratio = 16
> Step1:
> Insert delay block [0, 31] -> ei->i_reserved_data_blocks=2
> Step2:
> ext4_writepages
>   mpage_map_and_submit_extent -> return failed
>   mpage_release_unused_pages -> to release [0, 30]
>     ext4_es_remove_extent -> remove lblk=0 end=30
>       __es_remove_extent -> len1=0 len2=31-30=1
>  __es_remove_extent:
>  ...
>  if (len2 > 0) {
>   ...
> 	  if (len1 > 0) {
> 		  ...
> 	  } else {
> 		es->es_lblk = end + 1;
> 		es->es_len = len2;
> 		...
> 	  }
>   	if (count_reserved)
> 		count_rsvd(inode, lblk, ...);
> 	goto out; -> will return but didn't calculate 'reserved'
>  ...
> Step3:
> ext4_destroy_inode -> trigger "i_reserved_data_blocks (1) not cleared!"
> 
> To solve above issue if 'len2>0' call 'get_rsvd()' before goto out.
> 
> Reported-by: syzbot+05a0f0ccab4a25626e38@syzkaller.appspotmail.com
> Fixes: 8fcc3a580651 ("ext4: rework reserved cluster accounting when invalidating pages")
> Signed-off-by: Ye Bin <yebin10@huawei.com>
> ---
>  fs/ext4/extents_status.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/ext4/extents_status.c b/fs/ext4/extents_status.c
> index cd0a861853e3..7ada374ff27d 100644
> --- a/fs/ext4/extents_status.c
> +++ b/fs/ext4/extents_status.c
> @@ -1371,7 +1371,7 @@ static int __es_remove_extent(struct inode *inode, ext4_lblk_t lblk,
>  		if (count_reserved)
>  			count_rsvd(inode, lblk, orig_es.es_len - len1 - len2,
>  				   &orig_es, &rc);
> -		goto out;
> +		goto out_get_reserved;
>  	}
>  
>  	if (len1 > 0) {
> @@ -1413,6 +1413,7 @@ static int __es_remove_extent(struct inode *inode, ext4_lblk_t lblk,
>  		}
>  	}
>  
> +out_get_reserved:
>  	if (count_reserved)
>  		*reserved = get_rsvd(inode, end, es, &rc);
>  out:
> -- 

OK, this looks good.

As before, feel free to add:

Reviewed-by: Eric Whitney <enwlinux@gmail.com>

> 2.31.1
>
Theodore Ts'o Dec. 9, 2022, 6:02 a.m. UTC | #2 
On Thu, Dec 08, 2022 at 11:34:24AM +0800, Ye Bin wrote:
> From: Ye Bin <yebin10@huawei.com>
> 

Thanks, applied with an edit commit description to make it clearer
what's being fixed.

    ext4: fix reserved cluster accounting in __es_remove_extent()
    
    When bigalloc is enabled, reserved cluster accounting for delayed
    allocation is handled in extent_status.c.  With a corrupted file
    system, it's possible for this accounting to be incorrect,
    dsicovered by Syzbot:
    
	....

In general, it's better to explain what is being changed and why, and
put the big messy Syzbot change after the English description of the
change.  Remember, what's important is that we make ext4 better ---
not that we are getting rid of a Syzbot report.  When someone reads
the commit description later, what they will care about is how the
code has been improved.

Cheers,

					- Ted

> Syzbot report issue as follows:
> EXT4-fs error (device loop0): ext4_validate_block_bitmap:398: comm rep:
> 	bg 0: block 5: invalid block bitmap
> EXT4-fs (loop0): Delayed block allocation failed for inode 18 at logical
> 	offset 0 with max blocks 32 with error 28
> EXT4-fs (loop0): This should not happen!! Data will be lost
> 
> EXT4-fs (loop0): Total free blocks count 0
> EXT4-fs (loop0): Free/Dirty block details
> EXT4-fs (loop0): free_blocks=0
> EXT4-fs (loop0): dirty_blocks=32
> EXT4-fs (loop0): Block reservation details
> EXT4-fs (loop0): i_reserved_data_blocks=2
> EXT4-fs (loop0): Inode 18 (00000000845cd634):
> 	i_reserved_data_blocks (1) not cleared!
> 
> Above issue happens as follows:
> Assume:
> sbi->s_cluster_ratio = 16
> Step1:
> Insert delay block [0, 31] -> ei->i_reserved_data_blocks=2
> Step2:
> ext4_writepages
>   mpage_map_and_submit_extent -> return failed
>   mpage_release_unused_pages -> to release [0, 30]
>     ext4_es_remove_extent -> remove lblk=0 end=30
>       __es_remove_extent -> len1=0 len2=31-30=1
>  __es_remove_extent:
>  ...
>  if (len2 > 0) {
>   ...
> 	  if (len1 > 0) {
> 		  ...
> 	  } else {
> 		es->es_lblk = end + 1;
> 		es->es_len = len2;
> 		...
> 	  }
>   	if (count_reserved)
> 		count_rsvd(inode, lblk, ...);
> 	goto out; -> will return but didn't calculate 'reserved'
>  ...
> Step3:
> ext4_destroy_inode -> trigger "i_reserved_data_blocks (1) not cleared!"
> 
> To solve above issue if 'len2>0' call 'get_rsvd()' before goto out.
> 
> Reported-by: syzbot+05a0f0ccab4a25626e38@syzkaller.appspotmail.com
> Fixes: 8fcc3a580651 ("ext4: rework reserved cluster accounting when invalidating pages")
> Signed-off-by: Ye Bin <yebin10@huawei.com>
> ---
>  fs/ext4/extents_status.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/ext4/extents_status.c b/fs/ext4/extents_status.c
> index cd0a861853e3..7ada374ff27d 100644
> --- a/fs/ext4/extents_status.c
> +++ b/fs/ext4/extents_status.c
> @@ -1371,7 +1371,7 @@ static int __es_remove_extent(struct inode *inode, ext4_lblk_t lblk,
>  		if (count_reserved)
>  			count_rsvd(inode, lblk, orig_es.es_len - len1 - len2,
>  				   &orig_es, &rc);
> -		goto out;
> +		goto out_get_reserved;
>  	}
>  
>  	if (len1 > 0) {
> @@ -1413,6 +1413,7 @@ static int __es_remove_extent(struct inode *inode, ext4_lblk_t lblk,
>  		}
>  	}
>  
> +out_get_reserved:
>  	if (count_reserved)
>  		*reserved = get_rsvd(inode, end, es, &rc);
>  out:
> -- 
> 2.31.1
>
diff mbox series

Patch

diff --git a/fs/ext4/extents_status.c b/fs/ext4/extents_status.c
index cd0a861853e3..7ada374ff27d 100644
--- a/fs/ext4/extents_status.c
+++ b/fs/ext4/extents_status.c
@@ -1371,7 +1371,7 @@  static int __es_remove_extent(struct inode *inode, ext4_lblk_t lblk,
 		if (count_reserved)
 			count_rsvd(inode, lblk, orig_es.es_len - len1 - len2,
 				   &orig_es, &rc);
-		goto out;
+		goto out_get_reserved;
 	}
 
 	if (len1 > 0) {
@@ -1413,6 +1413,7 @@  static int __es_remove_extent(struct inode *inode, ext4_lblk_t lblk,
 		}
 	}
 
+out_get_reserved:
 	if (count_reserved)
 		*reserved = get_rsvd(inode, end, es, &rc);
 out: