Re: [PATCH 2/7] ecryptfs: streamline truncate_upper

[Tyler Hicks <code@tyhicks.com>]

On 2026-04-08 08:06:37, Christoph Hellwig wrote:
> Use a few strategic gotos to keep reduce indentation and keep the
> main reduce size flow outside of branches.  Switch all touched comments
> to normal kernel style and avoid breaks in printed strings for all
> the code touched.

That garbled first sentence is still here. I'll touch it up according to
our email exchange on v1.

Tyler

> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  fs/ecryptfs/inode.c | 115 +++++++++++++++++++++++---------------------
>  1 file changed, 60 insertions(+), 55 deletions(-)
> 
> diff --git a/fs/ecryptfs/inode.c b/fs/ecryptfs/inode.c
> index 81cf42d01ec5..695573850569 100644
> --- a/fs/ecryptfs/inode.c
> +++ b/fs/ecryptfs/inode.c
> @@ -725,83 +725,88 @@ upper_size_to_lower_size(struct ecryptfs_crypt_stat *crypt_stat,
>  static int truncate_upper(struct dentry *dentry, struct iattr *ia,
>  			  struct iattr *lower_ia)
>  {
> -	int rc = 0;
>  	struct inode *inode = d_inode(dentry);
>  	struct ecryptfs_crypt_stat *crypt_stat;
>  	loff_t i_size = i_size_read(inode);
>  	loff_t lower_size_before_truncate;
>  	loff_t lower_size_after_truncate;
> +	size_t num_zeros;
> +	int rc;
>  
>  	if (unlikely((ia->ia_size == i_size))) {
>  		lower_ia->ia_valid &= ~ATTR_SIZE;
>  		return 0;
>  	}
> +
>  	rc = ecryptfs_get_lower_file(dentry, inode);
>  	if (rc)
>  		return rc;
> -	crypt_stat = &ecryptfs_inode_to_private(d_inode(dentry))->crypt_stat;
> -	/* Switch on growing or shrinking file */
> +
>  	if (ia->ia_size > i_size) {
>  		char zero[] = { 0x00 };
>  
> +		/*
> +		 * Write a single 0 at the last position of the file; this
> +		 * triggers code that will fill in 0's throughout the
> +		 * intermediate portion of the previous end of the file and the
> +		 * new end of the file.
> +		 */
> +		rc = ecryptfs_write(inode, zero, ia->ia_size - 1, 1);
>  		lower_ia->ia_valid &= ~ATTR_SIZE;
> -		/* Write a single 0 at the last position of the file;
> -		 * this triggers code that will fill in 0's throughout
> -		 * the intermediate portion of the previous end of the
> -		 * file and the new and of the file */
> -		rc = ecryptfs_write(inode, zero,
> -				    (ia->ia_size - 1), 1);
> -	} else { /* ia->ia_size < i_size_read(inode) */
> -		/* We're chopping off all the pages down to the page
> -		 * in which ia->ia_size is located. Fill in the end of
> -		 * that page from (ia->ia_size & ~PAGE_MASK) to
> -		 * PAGE_SIZE with zeros. */
> -		size_t num_zeros = (PAGE_SIZE
> -				    - (ia->ia_size & ~PAGE_MASK));
> -
> -		if (!(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
> -			truncate_setsize(inode, ia->ia_size);
> -			lower_ia->ia_size = ia->ia_size;
> -			lower_ia->ia_valid |= ATTR_SIZE;
> -			goto out;
> -		}
> -		if (num_zeros) {
> -			char *zeros_virt;
> +		goto out;
> +	}
>  
> -			zeros_virt = kzalloc(num_zeros, GFP_KERNEL);
> -			if (!zeros_virt) {
> -				rc = -ENOMEM;
> -				goto out;
> -			}
> -			rc = ecryptfs_write(inode, zeros_virt,
> -					    ia->ia_size, num_zeros);
> -			kfree(zeros_virt);
> -			if (rc) {
> -				printk(KERN_ERR "Error attempting to zero out "
> -				       "the remainder of the end page on "
> -				       "reducing truncate; rc = [%d]\n", rc);
> -				goto out;
> -			}
> -		}
> +	crypt_stat = &ecryptfs_inode_to_private(d_inode(dentry))->crypt_stat;
> +	if (!(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
>  		truncate_setsize(inode, ia->ia_size);
> -		rc = ecryptfs_write_inode_size_to_metadata(inode);
> +		lower_ia->ia_size = ia->ia_size;
> +		lower_ia->ia_valid |= ATTR_SIZE;
> +		goto out;
> +	}
> +
> +	/*
> +	 * We're chopping off all the pages down to the page in which
> +	 * ia->ia_size is located. Fill in the end of that page from
> +	 * (ia->ia_size & ~PAGE_MASK) to PAGE_SIZE with zeros.
> +	 */
> +	num_zeros = PAGE_SIZE - (ia->ia_size & ~PAGE_MASK);
> +	if (num_zeros) {
> +		char *zeros_virt;
> +
> +		zeros_virt = kzalloc(num_zeros, GFP_KERNEL);
> +		if (!zeros_virt) {
> +			rc = -ENOMEM;
> +			goto out;
> +		}
> +		rc = ecryptfs_write(inode, zeros_virt, ia->ia_size, num_zeros);
> +		kfree(zeros_virt);
>  		if (rc) {
> -			printk(KERN_ERR	"Problem with "
> -			       "ecryptfs_write_inode_size_to_metadata; "
> -			       "rc = [%d]\n", rc);
> +			pr_err("Error attempting to zero out the remainder of the end page on reducing truncate; rc = [%d]\n",
> +				rc);
>  			goto out;
>  		}
> -		/* We are reducing the size of the ecryptfs file, and need to
> -		 * know if we need to reduce the size of the lower file. */
> -		lower_size_before_truncate =
> -		    upper_size_to_lower_size(crypt_stat, i_size);
> -		lower_size_after_truncate =
> -		    upper_size_to_lower_size(crypt_stat, ia->ia_size);
> -		if (lower_size_after_truncate < lower_size_before_truncate) {
> -			lower_ia->ia_size = lower_size_after_truncate;
> -			lower_ia->ia_valid |= ATTR_SIZE;
> -		} else
> -			lower_ia->ia_valid &= ~ATTR_SIZE;
> +	}
> +	truncate_setsize(inode, ia->ia_size);
> +	rc = ecryptfs_write_inode_size_to_metadata(inode);
> +	if (rc) {
> +		pr_err("Problem with ecryptfs_write_inode_size_to_metadata; rc = [%d]\n",
> +			rc);
> +		goto out;
> +	}
> +
> +	/*
> +	 * We are reducing the size of the ecryptfs file, and need to know if we
> +	 * need to reduce the size of the lower file.
> +	 */
> +	lower_size_before_truncate =
> +		upper_size_to_lower_size(crypt_stat, i_size);
> +	lower_size_after_truncate =
> +		upper_size_to_lower_size(crypt_stat, ia->ia_size);
> +	if (lower_size_after_truncate < lower_size_before_truncate) {
> +		lower_ia->ia_size = lower_size_after_truncate;
> +		lower_ia->ia_valid |= ATTR_SIZE;
> +	} else {
> +		lower_ia->ia_valid &= ~ATTR_SIZE;
>  	}
>  out:
>  	ecryptfs_put_lower_file(inode);
> -- 
> 2.47.3
>