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[PATCH v2] ext4: do not check fast symlink during orphan recovery

Zhang Yi posted 1 patch 1 week, 1 day ago 
fs/ext4/inode.c | 40 +++++++++++++++++++++++++++++-----------
1 file changed, 29 insertions(+), 11 deletions(-)
[PATCH v2] ext4: do not check fast symlink during orphan recovery
Posted by Zhang Yi 1 week, 1 day ago 
From: Zhang Yi <yi.zhang@huawei.com>

Commit '5f920d5d6083 ("ext4: verify fast symlink length")' causes the
generic/475 test to fail during orphan cleanup of zero-length symlinks.

  generic/475  84s ... _check_generic_filesystem: filesystem on /dev/vde is inconsistent

The fsck reports are provided below:

  Deleted inode 9686 has zero dtime.
  Deleted inode 158230 has zero dtime.
  ...
  Inode bitmap differences:  -9686 -158230
  Orphan file (inode 12) block 13 is not clean.
  Failed to initialize orphan file.

In ext4_symlink(), a newly created symlink can be added to the orphan
list due to ENOSPC. Its data has not been initialized, and its size is
zero. Therefore, we need to disregard the length check of the symbolic
link when cleaning up orphan inodes. Instead, we should ensure that the
nlink count is zero.

Fixes: 5f920d5d6083 ("ext4: verify fast symlink length")
Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
---
Changes since v1:
 - Improve the comment and add nlink check during orphan cleanup as Jan
   suggested.

 fs/ext4/inode.c | 40 +++++++++++++++++++++++++++++-----------
 1 file changed, 29 insertions(+), 11 deletions(-)

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 129594bf8311..cfb66f7ad3d7 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -6073,18 +6073,36 @@ struct inode *__ext4_iget(struct super_block *sb, unsigned long ino,
 			inode->i_op = &ext4_encrypted_symlink_inode_operations;
 		} else if (ext4_inode_is_fast_symlink(inode)) {
 			inode->i_op = &ext4_fast_symlink_inode_operations;
-			if (inode->i_size == 0 ||
-			    inode->i_size >= sizeof(ei->i_data) ||
-			    strnlen((char *)ei->i_data, inode->i_size + 1) !=
-								inode->i_size) {
-				ext4_error_inode(inode, function, line, 0,
-					"invalid fast symlink length %llu",
-					 (unsigned long long)inode->i_size);
-				ret = -EFSCORRUPTED;
-				goto bad_inode;
+
+			/*
+			 * Orphan cleanup can see inodes with i_size == 0
+			 * and i_data uninitialized. Skip size checks in
+			 * that case. This is safe because the first thing
+			 * ext4_evict_inode() does for fast symlinks is
+			 * clearing of i_data and i_size.
+			 */
+			if ((EXT4_SB(sb)->s_mount_state & EXT4_ORPHAN_FS)) {
+				if (inode->i_nlink != 0) {
+					ext4_error_inode(inode, function, line, 0,
+						"invalid orphan symlink nlink %d",
+						inode->i_nlink);
+					ret = -EFSCORRUPTED;
+					goto bad_inode;
+				}
+			} else {
+				if (inode->i_size == 0 ||
+				    inode->i_size >= sizeof(ei->i_data) ||
+				    strnlen((char *)ei->i_data, inode->i_size + 1) !=
+						inode->i_size) {
+					ext4_error_inode(inode, function, line, 0,
+						"invalid fast symlink length %llu",
+						(unsigned long long)inode->i_size);
+					ret = -EFSCORRUPTED;
+					goto bad_inode;
+				}
+				inode_set_cached_link(inode, (char *)ei->i_data,
+						      inode->i_size);
 			}
-			inode_set_cached_link(inode, (char *)ei->i_data,
-					      inode->i_size);
 		} else {
 			inode->i_op = &ext4_symlink_inode_operations;
 		}
-- 
2.52.0
Re: [PATCH v2] ext4: do not check fast symlink during orphan recovery
Posted by Jan Kara 6 days, 4 hours ago 
On Sat 31-01-26 17:11:56, Zhang Yi wrote:
> From: Zhang Yi <yi.zhang@huawei.com>
> 
> Commit '5f920d5d6083 ("ext4: verify fast symlink length")' causes the
> generic/475 test to fail during orphan cleanup of zero-length symlinks.
> 
>   generic/475  84s ... _check_generic_filesystem: filesystem on /dev/vde is inconsistent
> 
> The fsck reports are provided below:
> 
>   Deleted inode 9686 has zero dtime.
>   Deleted inode 158230 has zero dtime.
>   ...
>   Inode bitmap differences:  -9686 -158230
>   Orphan file (inode 12) block 13 is not clean.
>   Failed to initialize orphan file.
> 
> In ext4_symlink(), a newly created symlink can be added to the orphan
> list due to ENOSPC. Its data has not been initialized, and its size is
> zero. Therefore, we need to disregard the length check of the symbolic
> link when cleaning up orphan inodes. Instead, we should ensure that the
> nlink count is zero.
> 
> Fixes: 5f920d5d6083 ("ext4: verify fast symlink length")
> Signed-off-by: Zhang Yi <yi.zhang@huawei.com>

Looks good! Feel free to add:

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

								Honza

> ---
> Changes since v1:
>  - Improve the comment and add nlink check during orphan cleanup as Jan
>    suggested.
> 
>  fs/ext4/inode.c | 40 +++++++++++++++++++++++++++++-----------
>  1 file changed, 29 insertions(+), 11 deletions(-)
> 
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 129594bf8311..cfb66f7ad3d7 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -6073,18 +6073,36 @@ struct inode *__ext4_iget(struct super_block *sb, unsigned long ino,
>  			inode->i_op = &ext4_encrypted_symlink_inode_operations;
>  		} else if (ext4_inode_is_fast_symlink(inode)) {
>  			inode->i_op = &ext4_fast_symlink_inode_operations;
> -			if (inode->i_size == 0 ||
> -			    inode->i_size >= sizeof(ei->i_data) ||
> -			    strnlen((char *)ei->i_data, inode->i_size + 1) !=
> -								inode->i_size) {
> -				ext4_error_inode(inode, function, line, 0,
> -					"invalid fast symlink length %llu",
> -					 (unsigned long long)inode->i_size);
> -				ret = -EFSCORRUPTED;
> -				goto bad_inode;
> +
> +			/*
> +			 * Orphan cleanup can see inodes with i_size == 0
> +			 * and i_data uninitialized. Skip size checks in
> +			 * that case. This is safe because the first thing
> +			 * ext4_evict_inode() does for fast symlinks is
> +			 * clearing of i_data and i_size.
> +			 */
> +			if ((EXT4_SB(sb)->s_mount_state & EXT4_ORPHAN_FS)) {
> +				if (inode->i_nlink != 0) {
> +					ext4_error_inode(inode, function, line, 0,
> +						"invalid orphan symlink nlink %d",
> +						inode->i_nlink);
> +					ret = -EFSCORRUPTED;
> +					goto bad_inode;
> +				}
> +			} else {
> +				if (inode->i_size == 0 ||
> +				    inode->i_size >= sizeof(ei->i_data) ||
> +				    strnlen((char *)ei->i_data, inode->i_size + 1) !=
> +						inode->i_size) {
> +					ext4_error_inode(inode, function, line, 0,
> +						"invalid fast symlink length %llu",
> +						(unsigned long long)inode->i_size);
> +					ret = -EFSCORRUPTED;
> +					goto bad_inode;
> +				}
> +				inode_set_cached_link(inode, (char *)ei->i_data,
> +						      inode->i_size);
>  			}
> -			inode_set_cached_link(inode, (char *)ei->i_data,
> -					      inode->i_size);
>  		} else {
>  			inode->i_op = &ext4_symlink_inode_operations;
>  		}
> -- 
> 2.52.0
> 
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR

Patchew 2.1-devel-b67e4c2

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