ACK: [PATCH 1/1] eCryptfs: Use notify_change for truncating lower inodes
Stefan Bader
stefan.bader at canonical.com
Thu Feb 16 14:49:01 UTC 2012
On 16.02.2012 15:38, Colin King wrote:
> From: Colin Ian King <colin.king at canonical.com>
>
> When truncating inodes in the lower filesystem, eCryptfs directly
> invoked vmtruncate(). As Christoph Hellwig pointed out, vmtruncate() is
> a filesystem helper function, but filesystems may need to do more than
> just a call to vmtruncate().
>
> This patch moves the lower inode truncation out of ecryptfs_truncate()
> and renames the function to truncate_upper(). truncate_upper() updates
> an iattr for the lower inode to indicate if the lower inode needs to be
> truncated upon return. ecryptfs_setattr() then calls notify_change(),
> using the updated iattr for the lower inode, to complete the truncation.
>
> For eCryptfs functions needing to truncate, ecryptfs_truncate() is
> reintroduced as a simple way to truncate the upper inode to a specified
> size and then truncate the lower inode accordingly.
>
> https://bugs.launchpad.net/bugs/451368
>
> This is a backport of commit 5f3ef64f4da1c587cdcfaaac72311225b7df094c
>
> Reported-by: Christoph Hellwig <hch at lst.de>
> Acked-by: Dustin Kirkland <kirkland at canonical.com>
> Cc: ecryptfs-devel at lists.launchpad.net
> Cc: linux-fsdevel at vger.kernel.org
> Signed-off-by: Tyler Hicks <tyhicks at linux.vnet.ibm.com>
> Signed-off-by: Colin Ian King <colin.king at canonical.com>
> ---
> fs/ecryptfs/inode.c | 99 ++++++++++++++++++++++++++++++++++----------------
> 1 files changed, 67 insertions(+), 32 deletions(-)
>
> diff --git a/fs/ecryptfs/inode.c b/fs/ecryptfs/inode.c
> index 88ba4d4..7ce5471 100644
> --- a/fs/ecryptfs/inode.c
> +++ b/fs/ecryptfs/inode.c
> @@ -758,18 +758,23 @@ upper_size_to_lower_size(struct ecryptfs_crypt_stat *crypt_stat,
> }
>
> /**
> - * ecryptfs_truncate
> + * truncate_upper
> * @dentry: The ecryptfs layer dentry
> - * @new_length: The length to expand the file to
> + * @ia: Address of the ecryptfs inode's attributes
> + * @lower_ia: Address of the lower inode's attributes
> *
> * Function to handle truncations modifying the size of the file. Note
> * that the file sizes are interpolated. When expanding, we are simply
> - * writing strings of 0's out. When truncating, we need to modify the
> - * underlying file size according to the page index interpolations.
> + * writing strings of 0's out. When truncating, we truncate the upper
> + * inode and update the lower_ia according to the page index
> + * interpolations. If ATTR_SIZE is set in lower_ia->ia_valid upon return,
> + * the caller must use lower_ia in a call to notify_change() to perform
> + * the truncation of the lower inode.
> *
> * Returns zero on success; non-zero otherwise
> */
> -int ecryptfs_truncate(struct dentry *dentry, loff_t new_length)
> +static int truncate_upper(struct dentry *dentry, struct iattr *ia,
> + struct iattr *lower_ia)
> {
> int rc = 0;
> struct inode *inode = dentry->d_inode;
> @@ -780,8 +785,10 @@ int ecryptfs_truncate(struct dentry *dentry, loff_t new_length)
> loff_t lower_size_before_truncate;
> loff_t lower_size_after_truncate;
>
> - if (unlikely((new_length == i_size)))
> + if (unlikely((ia->ia_size == i_size))) {
> + lower_ia->ia_valid &= ~ATTR_SIZE;
> goto out;
> + }
> crypt_stat = &ecryptfs_inode_to_private(dentry->d_inode)->crypt_stat;
> /* Set up a fake ecryptfs file, this is used to interface with
> * the file in the underlying filesystem so that the
> @@ -801,28 +808,30 @@ int ecryptfs_truncate(struct dentry *dentry, loff_t new_length)
> &fake_ecryptfs_file,
> ecryptfs_inode_to_private(dentry->d_inode)->lower_file);
> /* Switch on growing or shrinking file */
> - if (new_length > i_size) {
> + if (ia->ia_size > i_size) {
> char zero[] = { 0x00 };
>
> + 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(&fake_ecryptfs_file, zero,
> - (new_length - 1), 1);
> - } else { /* new_length < i_size_read(inode) */
> - /* We're chopping off all the pages down do the page
> - * in which new_length is located. Fill in the end of
> - * that page from (new_length & ~PAGE_CACHE_MASK) to
> + (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_CACHE_MASK) to
> * PAGE_CACHE_SIZE with zeros. */
> size_t num_zeros = (PAGE_CACHE_SIZE
> - - (new_length & ~PAGE_CACHE_MASK));
> + - (ia->ia_size & ~PAGE_CACHE_MASK));
>
> if (!(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
> - rc = vmtruncate(inode, new_length);
> + rc = vmtruncate(inode, ia->ia_size);
> if (rc)
> goto out_free;
> - rc = vmtruncate(lower_dentry->d_inode, new_length);
> + lower_ia->ia_size = ia->ia_size;
> + lower_ia->ia_valid |= ATTR_SIZE;
> goto out_free;
> }
> if (num_zeros) {
> @@ -834,7 +843,7 @@ int ecryptfs_truncate(struct dentry *dentry, loff_t new_length)
> goto out_free;
> }
> rc = ecryptfs_write(&fake_ecryptfs_file, zeros_virt,
> - new_length, num_zeros);
> + ia->ia_size, num_zeros);
> kfree(zeros_virt);
> if (rc) {
> printk(KERN_ERR "Error attempting to zero out "
> @@ -843,7 +852,7 @@ int ecryptfs_truncate(struct dentry *dentry, loff_t new_length)
> goto out_free;
> }
> }
> - vmtruncate(inode, new_length);
> + vmtruncate(inode, ia->ia_size);
> rc = ecryptfs_write_inode_size_to_metadata(inode);
> if (rc) {
> printk(KERN_ERR "Problem with "
> @@ -856,10 +865,12 @@ int ecryptfs_truncate(struct dentry *dentry, loff_t new_length)
> lower_size_before_truncate =
> upper_size_to_lower_size(crypt_stat, i_size);
> lower_size_after_truncate =
> - upper_size_to_lower_size(crypt_stat, new_length);
> - if (lower_size_after_truncate < lower_size_before_truncate)
> - vmtruncate(lower_dentry->d_inode,
> - 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_free:
> if (ecryptfs_file_to_private(&fake_ecryptfs_file))
> @@ -869,6 +880,33 @@ out:
> return rc;
> }
>
> +/**
> + * ecryptfs_truncate
> + * @dentry: The ecryptfs layer dentry
> + * @new_length: The length to expand the file to
> + *
> + * Simple function that handles the truncation of an eCryptfs inode and
> + * its corresponding lower inode.
> + *
> + * Returns zero on success; non-zero otherwise
> + */
> +int ecryptfs_truncate(struct dentry *dentry, loff_t new_length)
> +{
> + struct iattr ia = { .ia_valid = ATTR_SIZE, .ia_size = new_length };
> + struct iattr lower_ia = { .ia_valid = 0 };
> + int rc;
> +
> + rc = truncate_upper(dentry, &ia, &lower_ia);
> + if (!rc && lower_ia.ia_valid & ATTR_SIZE) {
> + struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
> +
> + mutex_lock(&lower_dentry->d_inode->i_mutex);
> + rc = notify_change(lower_dentry, &lower_ia);
> + mutex_unlock(&lower_dentry->d_inode->i_mutex);
> + }
> + return rc;
> +}
> +
> static int
> ecryptfs_permission(struct inode *inode, int mask)
> {
> @@ -891,6 +929,7 @@ static int ecryptfs_setattr(struct dentry *dentry, struct iattr *ia)
> {
> int rc = 0;
> struct dentry *lower_dentry;
> + struct iattr lower_ia;
> struct inode *inode;
> struct inode *lower_inode;
> struct ecryptfs_crypt_stat *crypt_stat;
> @@ -929,15 +968,11 @@ static int ecryptfs_setattr(struct dentry *dentry, struct iattr *ia)
> }
> }
> mutex_unlock(&crypt_stat->cs_mutex);
> + memcpy(&lower_ia, ia, sizeof(lower_ia));
> + if (ia->ia_valid & ATTR_FILE)
> + lower_ia.ia_file = ecryptfs_file_to_lower(ia->ia_file);
> if (ia->ia_valid & ATTR_SIZE) {
> - ecryptfs_printk(KERN_DEBUG,
> - "ia->ia_valid = [0x%x] ATTR_SIZE" " = [0x%x]\n",
> - ia->ia_valid, ATTR_SIZE);
> - rc = ecryptfs_truncate(dentry, ia->ia_size);
> - /* ecryptfs_truncate handles resizing of the lower file */
> - ia->ia_valid &= ~ATTR_SIZE;
> - ecryptfs_printk(KERN_DEBUG, "ia->ia_valid = [%x]\n",
> - ia->ia_valid);
> + rc = truncate_upper(dentry, ia, &lower_ia);
> if (rc < 0)
> goto out;
> }
> @@ -946,11 +981,11 @@ static int ecryptfs_setattr(struct dentry *dentry, struct iattr *ia)
> * mode change is for clearing setuid/setgid bits. Allow lower fs
> * to interpret this in its own way.
> */
> - if (ia->ia_valid & (ATTR_KILL_SUID | ATTR_KILL_SGID))
> - ia->ia_valid &= ~ATTR_MODE;
> + if (lower_ia.ia_valid & (ATTR_KILL_SUID | ATTR_KILL_SGID))
> + lower_ia.ia_valid &= ~ATTR_MODE;
>
> mutex_lock(&lower_dentry->d_inode->i_mutex);
> - rc = notify_change(lower_dentry, ia);
> + rc = notify_change(lower_dentry, &lower_ia);
> mutex_unlock(&lower_dentry->d_inode->i_mutex);
> out:
> fsstack_copy_attr_all(inode, lower_inode, NULL);
In upstream since 2.6.33, looking similar as the backport and trusting Colin's
testing...
Acked-by: Stefan Bader <stefan.bader at canonical.com>
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