eCryptfs: Use notify_change for truncating lower inodes
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 Reported-by: Christoph Hellwig <hch@lst.de> Acked-by: Dustin Kirkland <kirkland@canonical.com> Cc: ecryptfs-devel@lists.launchpad.net Cc: linux-fsdevel@vger.kernel.org Signed-off-by: Tyler Hicks <tyhicks@linux.vnet.ibm.com>
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@ -772,18 +772,23 @@ upper_size_to_lower_size(struct ecryptfs_crypt_stat *crypt_stat,
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}
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/**
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* ecryptfs_truncate
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* truncate_upper
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* @dentry: The ecryptfs layer dentry
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* @new_length: The length to expand the file to
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* @ia: Address of the ecryptfs inode's attributes
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* @lower_ia: Address of the lower inode's attributes
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*
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* Function to handle truncations modifying the size of the file. Note
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* that the file sizes are interpolated. When expanding, we are simply
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* writing strings of 0's out. When truncating, we need to modify the
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* underlying file size according to the page index interpolations.
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* writing strings of 0's out. When truncating, we truncate the upper
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* inode and update the lower_ia according to the page index
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* interpolations. If ATTR_SIZE is set in lower_ia->ia_valid upon return,
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* the caller must use lower_ia in a call to notify_change() to perform
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* the truncation of the lower inode.
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*
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* Returns zero on success; non-zero otherwise
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*/
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int ecryptfs_truncate(struct dentry *dentry, loff_t new_length)
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static int truncate_upper(struct dentry *dentry, struct iattr *ia,
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struct iattr *lower_ia)
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{
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int rc = 0;
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struct inode *inode = dentry->d_inode;
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@ -794,8 +799,10 @@ int ecryptfs_truncate(struct dentry *dentry, loff_t new_length)
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loff_t lower_size_before_truncate;
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loff_t lower_size_after_truncate;
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if (unlikely((new_length == i_size)))
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if (unlikely((ia->ia_size == i_size))) {
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lower_ia->ia_valid &= ~ATTR_SIZE;
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goto out;
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}
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crypt_stat = &ecryptfs_inode_to_private(dentry->d_inode)->crypt_stat;
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/* Set up a fake ecryptfs file, this is used to interface with
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* the file in the underlying filesystem so that the
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@ -815,28 +822,30 @@ int ecryptfs_truncate(struct dentry *dentry, loff_t new_length)
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&fake_ecryptfs_file,
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ecryptfs_inode_to_private(dentry->d_inode)->lower_file);
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/* Switch on growing or shrinking file */
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if (new_length > i_size) {
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if (ia->ia_size > i_size) {
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char zero[] = { 0x00 };
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lower_ia->ia_valid &= ~ATTR_SIZE;
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/* Write a single 0 at the last position of the file;
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* this triggers code that will fill in 0's throughout
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* the intermediate portion of the previous end of the
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* file and the new and of the file */
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rc = ecryptfs_write(&fake_ecryptfs_file, zero,
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(new_length - 1), 1);
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} else { /* new_length < i_size_read(inode) */
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/* We're chopping off all the pages down do the page
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* in which new_length is located. Fill in the end of
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* that page from (new_length & ~PAGE_CACHE_MASK) to
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(ia->ia_size - 1), 1);
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} else { /* ia->ia_size < i_size_read(inode) */
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/* We're chopping off all the pages down to the page
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* in which ia->ia_size is located. Fill in the end of
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* that page from (ia->ia_size & ~PAGE_CACHE_MASK) to
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* PAGE_CACHE_SIZE with zeros. */
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size_t num_zeros = (PAGE_CACHE_SIZE
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- (new_length & ~PAGE_CACHE_MASK));
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- (ia->ia_size & ~PAGE_CACHE_MASK));
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if (!(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
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rc = vmtruncate(inode, new_length);
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rc = vmtruncate(inode, ia->ia_size);
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if (rc)
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goto out_free;
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rc = vmtruncate(lower_dentry->d_inode, new_length);
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lower_ia->ia_size = ia->ia_size;
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lower_ia->ia_valid |= ATTR_SIZE;
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goto out_free;
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}
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if (num_zeros) {
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@ -848,7 +857,7 @@ int ecryptfs_truncate(struct dentry *dentry, loff_t new_length)
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goto out_free;
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}
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rc = ecryptfs_write(&fake_ecryptfs_file, zeros_virt,
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new_length, num_zeros);
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ia->ia_size, num_zeros);
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kfree(zeros_virt);
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if (rc) {
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printk(KERN_ERR "Error attempting to zero out "
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@ -857,7 +866,7 @@ int ecryptfs_truncate(struct dentry *dentry, loff_t new_length)
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goto out_free;
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}
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}
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vmtruncate(inode, new_length);
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vmtruncate(inode, ia->ia_size);
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rc = ecryptfs_write_inode_size_to_metadata(inode);
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if (rc) {
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printk(KERN_ERR "Problem with "
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@ -870,10 +879,12 @@ int ecryptfs_truncate(struct dentry *dentry, loff_t new_length)
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lower_size_before_truncate =
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upper_size_to_lower_size(crypt_stat, i_size);
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lower_size_after_truncate =
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upper_size_to_lower_size(crypt_stat, new_length);
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if (lower_size_after_truncate < lower_size_before_truncate)
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vmtruncate(lower_dentry->d_inode,
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lower_size_after_truncate);
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upper_size_to_lower_size(crypt_stat, ia->ia_size);
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if (lower_size_after_truncate < lower_size_before_truncate) {
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lower_ia->ia_size = lower_size_after_truncate;
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lower_ia->ia_valid |= ATTR_SIZE;
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} else
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lower_ia->ia_valid &= ~ATTR_SIZE;
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}
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out_free:
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if (ecryptfs_file_to_private(&fake_ecryptfs_file))
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@ -883,6 +894,33 @@ out:
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return rc;
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}
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/**
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* ecryptfs_truncate
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* @dentry: The ecryptfs layer dentry
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* @new_length: The length to expand the file to
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*
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* Simple function that handles the truncation of an eCryptfs inode and
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* its corresponding lower inode.
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*
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* Returns zero on success; non-zero otherwise
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*/
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int ecryptfs_truncate(struct dentry *dentry, loff_t new_length)
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{
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struct iattr ia = { .ia_valid = ATTR_SIZE, .ia_size = new_length };
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struct iattr lower_ia = { .ia_valid = 0 };
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int rc;
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rc = truncate_upper(dentry, &ia, &lower_ia);
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if (!rc && lower_ia.ia_valid & ATTR_SIZE) {
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struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
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mutex_lock(&lower_dentry->d_inode->i_mutex);
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rc = notify_change(lower_dentry, &lower_ia);
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mutex_unlock(&lower_dentry->d_inode->i_mutex);
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}
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return rc;
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}
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static int
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ecryptfs_permission(struct inode *inode, int mask)
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{
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@ -905,6 +943,7 @@ static int ecryptfs_setattr(struct dentry *dentry, struct iattr *ia)
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{
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int rc = 0;
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struct dentry *lower_dentry;
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struct iattr lower_ia;
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struct inode *inode;
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struct inode *lower_inode;
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struct ecryptfs_crypt_stat *crypt_stat;
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@ -943,15 +982,11 @@ static int ecryptfs_setattr(struct dentry *dentry, struct iattr *ia)
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}
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}
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mutex_unlock(&crypt_stat->cs_mutex);
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memcpy(&lower_ia, ia, sizeof(lower_ia));
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if (ia->ia_valid & ATTR_FILE)
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lower_ia.ia_file = ecryptfs_file_to_lower(ia->ia_file);
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if (ia->ia_valid & ATTR_SIZE) {
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ecryptfs_printk(KERN_DEBUG,
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"ia->ia_valid = [0x%x] ATTR_SIZE" " = [0x%x]\n",
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ia->ia_valid, ATTR_SIZE);
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rc = ecryptfs_truncate(dentry, ia->ia_size);
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/* ecryptfs_truncate handles resizing of the lower file */
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ia->ia_valid &= ~ATTR_SIZE;
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ecryptfs_printk(KERN_DEBUG, "ia->ia_valid = [%x]\n",
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ia->ia_valid);
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rc = truncate_upper(dentry, ia, &lower_ia);
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if (rc < 0)
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goto out;
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}
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@ -960,11 +995,11 @@ static int ecryptfs_setattr(struct dentry *dentry, struct iattr *ia)
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* mode change is for clearing setuid/setgid bits. Allow lower fs
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* to interpret this in its own way.
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*/
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if (ia->ia_valid & (ATTR_KILL_SUID | ATTR_KILL_SGID))
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ia->ia_valid &= ~ATTR_MODE;
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if (lower_ia.ia_valid & (ATTR_KILL_SUID | ATTR_KILL_SGID))
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lower_ia.ia_valid &= ~ATTR_MODE;
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mutex_lock(&lower_dentry->d_inode->i_mutex);
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rc = notify_change(lower_dentry, ia);
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rc = notify_change(lower_dentry, &lower_ia);
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mutex_unlock(&lower_dentry->d_inode->i_mutex);
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out:
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fsstack_copy_attr_all(inode, lower_inode);
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