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eCryptfs: Use notify_change for truncating lower inodes

Browse source 
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>
This commit is contained in:
Tyler Hicks 2009-10-14 16:18:27 -05:00
commit 5f3ef64f4d
1 changed files with 67 additions and 32 deletions
Download patch file Download diff file Expand all files Collapse all files

99
fs/ecryptfs/inode.c
View file

@ -772,18 +772,23 @@ 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;
@ -794,8 +799,10 @@ 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
@ -815,28 +822,30 @@ 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) {
@ -848,7 +857,7 @@ 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 "
@ -857,7 +866,7 @@ 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 "
@ -870,10 +879,12 @@ 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))
@ -883,6 +894,33 @@ 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)
{
@ -905,6 +943,7 @@ 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;
@ -943,15 +982,11 @@ 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;
}
@ -960,11 +995,11 @@ 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);