eCryptfs: fix write zeros behavior
This patch fixes the processes involved in wiping regions of the data during truncate and write events, fixing a kernel hang in 2.6.22-rc4 while assuring that zero values are written out to the appropriate locations during events in which the i_size will change. The range passed to ecryptfs_truncate() from ecryptfs_prepare_write() includes the page that is the object of ecryptfs_prepare_write(). This leads to a kernel hang as read_cache_page() is executed on the same page in the ecryptfs_truncate() execution path. This patch remedies this by limiting the range passed to ecryptfs_truncate() so as to exclude the page that is the object of ecryptfs_prepare_write(); it also adds code to ecryptfs_prepare_write() to zero out the region of its own page when writing past the i_size position. This patch also modifies ecryptfs_truncate() so that when a file is truncated to a smaller size, eCryptfs will zero out the contents of the new last page from the new size through to the end of the last page. Signed-off-by: Michael Halcrow <mhalcrow@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
parent
b75ae86035
commit
240e2df5c7
|
@ -580,5 +580,7 @@ void
|
||||||
ecryptfs_write_header_metadata(char *virt,
|
ecryptfs_write_header_metadata(char *virt,
|
||||||
struct ecryptfs_crypt_stat *crypt_stat,
|
struct ecryptfs_crypt_stat *crypt_stat,
|
||||||
size_t *written);
|
size_t *written);
|
||||||
|
int ecryptfs_write_zeros(struct file *file, pgoff_t index, int start,
|
||||||
|
int num_zeros);
|
||||||
|
|
||||||
#endif /* #ifndef ECRYPTFS_KERNEL_H */
|
#endif /* #ifndef ECRYPTFS_KERNEL_H */
|
||||||
|
|
|
@ -800,6 +800,25 @@ int ecryptfs_truncate(struct dentry *dentry, loff_t new_length)
|
||||||
goto out_fput;
|
goto out_fput;
|
||||||
}
|
}
|
||||||
} else { /* new_length < i_size_read(inode) */
|
} else { /* new_length < i_size_read(inode) */
|
||||||
|
pgoff_t index = 0;
|
||||||
|
int end_pos_in_page = -1;
|
||||||
|
|
||||||
|
if (new_length != 0) {
|
||||||
|
index = ((new_length - 1) >> PAGE_CACHE_SHIFT);
|
||||||
|
end_pos_in_page = ((new_length - 1) & ~PAGE_CACHE_MASK);
|
||||||
|
}
|
||||||
|
if (end_pos_in_page != (PAGE_CACHE_SIZE - 1)) {
|
||||||
|
if ((rc = ecryptfs_write_zeros(&fake_ecryptfs_file,
|
||||||
|
index,
|
||||||
|
(end_pos_in_page + 1),
|
||||||
|
((PAGE_CACHE_SIZE - 1)
|
||||||
|
- end_pos_in_page)))) {
|
||||||
|
printk(KERN_ERR "Error attempting to zero out "
|
||||||
|
"the remainder of the end page on "
|
||||||
|
"reducing truncate; rc = [%d]\n", rc);
|
||||||
|
goto out_fput;
|
||||||
|
}
|
||||||
|
}
|
||||||
vmtruncate(inode, new_length);
|
vmtruncate(inode, new_length);
|
||||||
rc = ecryptfs_write_inode_size_to_metadata(
|
rc = ecryptfs_write_inode_size_to_metadata(
|
||||||
lower_file, lower_dentry->d_inode, inode, dentry,
|
lower_file, lower_dentry->d_inode, inode, dentry,
|
||||||
|
|
|
@ -56,9 +56,6 @@ static struct page *ecryptfs_get1page(struct file *file, int index)
|
||||||
return read_mapping_page(mapping, index, (void *)file);
|
return read_mapping_page(mapping, index, (void *)file);
|
||||||
}
|
}
|
||||||
|
|
||||||
static
|
|
||||||
int write_zeros(struct file *file, pgoff_t index, int start, int num_zeros);
|
|
||||||
|
|
||||||
/**
|
/**
|
||||||
* ecryptfs_fill_zeros
|
* ecryptfs_fill_zeros
|
||||||
* @file: The ecryptfs file
|
* @file: The ecryptfs file
|
||||||
|
@ -101,10 +98,13 @@ int ecryptfs_fill_zeros(struct file *file, loff_t new_length)
|
||||||
if (old_end_page_index == new_end_page_index) {
|
if (old_end_page_index == new_end_page_index) {
|
||||||
/* Start and end are in the same page; we just need to
|
/* Start and end are in the same page; we just need to
|
||||||
* set a portion of the existing page to zero's */
|
* set a portion of the existing page to zero's */
|
||||||
rc = write_zeros(file, index, (old_end_pos_in_page + 1),
|
rc = ecryptfs_write_zeros(file, index,
|
||||||
(new_end_pos_in_page - old_end_pos_in_page));
|
(old_end_pos_in_page + 1),
|
||||||
|
(new_end_pos_in_page
|
||||||
|
- old_end_pos_in_page));
|
||||||
if (rc)
|
if (rc)
|
||||||
ecryptfs_printk(KERN_ERR, "write_zeros(file=[%p], "
|
ecryptfs_printk(KERN_ERR, "ecryptfs_write_zeros("
|
||||||
|
"file=[%p], "
|
||||||
"index=[0x%.16x], "
|
"index=[0x%.16x], "
|
||||||
"old_end_pos_in_page=[d], "
|
"old_end_pos_in_page=[d], "
|
||||||
"(PAGE_CACHE_SIZE - new_end_pos_in_page"
|
"(PAGE_CACHE_SIZE - new_end_pos_in_page"
|
||||||
|
@ -117,10 +117,10 @@ int ecryptfs_fill_zeros(struct file *file, loff_t new_length)
|
||||||
goto out;
|
goto out;
|
||||||
}
|
}
|
||||||
/* Fill the remainder of the previous last page with zeros */
|
/* Fill the remainder of the previous last page with zeros */
|
||||||
rc = write_zeros(file, index, (old_end_pos_in_page + 1),
|
rc = ecryptfs_write_zeros(file, index, (old_end_pos_in_page + 1),
|
||||||
((PAGE_CACHE_SIZE - 1) - old_end_pos_in_page));
|
((PAGE_CACHE_SIZE - 1) - old_end_pos_in_page));
|
||||||
if (rc) {
|
if (rc) {
|
||||||
ecryptfs_printk(KERN_ERR, "write_zeros(file=[%p], "
|
ecryptfs_printk(KERN_ERR, "ecryptfs_write_zeros(file=[%p], "
|
||||||
"index=[0x%.16x], old_end_pos_in_page=[d], "
|
"index=[0x%.16x], old_end_pos_in_page=[d], "
|
||||||
"(PAGE_CACHE_SIZE - old_end_pos_in_page)=[d]) "
|
"(PAGE_CACHE_SIZE - old_end_pos_in_page)=[d]) "
|
||||||
"returned [%d]\n", file, index,
|
"returned [%d]\n", file, index,
|
||||||
|
@ -131,9 +131,10 @@ int ecryptfs_fill_zeros(struct file *file, loff_t new_length)
|
||||||
index++;
|
index++;
|
||||||
while (index < new_end_page_index) {
|
while (index < new_end_page_index) {
|
||||||
/* Fill all intermediate pages with zeros */
|
/* Fill all intermediate pages with zeros */
|
||||||
rc = write_zeros(file, index, 0, PAGE_CACHE_SIZE);
|
rc = ecryptfs_write_zeros(file, index, 0, PAGE_CACHE_SIZE);
|
||||||
if (rc) {
|
if (rc) {
|
||||||
ecryptfs_printk(KERN_ERR, "write_zeros(file=[%p], "
|
ecryptfs_printk(KERN_ERR, "ecryptfs_write_zeros("
|
||||||
|
"file=[%p], "
|
||||||
"index=[0x%.16x], "
|
"index=[0x%.16x], "
|
||||||
"old_end_pos_in_page=[d], "
|
"old_end_pos_in_page=[d], "
|
||||||
"(PAGE_CACHE_SIZE - new_end_pos_in_page"
|
"(PAGE_CACHE_SIZE - new_end_pos_in_page"
|
||||||
|
@ -149,9 +150,9 @@ int ecryptfs_fill_zeros(struct file *file, loff_t new_length)
|
||||||
}
|
}
|
||||||
/* Fill the portion at the beginning of the last new page with
|
/* Fill the portion at the beginning of the last new page with
|
||||||
* zero's */
|
* zero's */
|
||||||
rc = write_zeros(file, index, 0, (new_end_pos_in_page + 1));
|
rc = ecryptfs_write_zeros(file, index, 0, (new_end_pos_in_page + 1));
|
||||||
if (rc) {
|
if (rc) {
|
||||||
ecryptfs_printk(KERN_ERR, "write_zeros(file="
|
ecryptfs_printk(KERN_ERR, "ecryptfs_write_zeros(file="
|
||||||
"[%p], index=[0x%.16x], 0, "
|
"[%p], index=[0x%.16x], 0, "
|
||||||
"new_end_pos_in_page=[%d]"
|
"new_end_pos_in_page=[%d]"
|
||||||
"returned [%d]\n", file, index,
|
"returned [%d]\n", file, index,
|
||||||
|
@ -400,7 +401,6 @@ out:
|
||||||
static int ecryptfs_prepare_write(struct file *file, struct page *page,
|
static int ecryptfs_prepare_write(struct file *file, struct page *page,
|
||||||
unsigned from, unsigned to)
|
unsigned from, unsigned to)
|
||||||
{
|
{
|
||||||
loff_t pos;
|
|
||||||
int rc = 0;
|
int rc = 0;
|
||||||
|
|
||||||
if (from == 0 && to == PAGE_CACHE_SIZE)
|
if (from == 0 && to == PAGE_CACHE_SIZE)
|
||||||
|
@ -408,14 +408,19 @@ static int ecryptfs_prepare_write(struct file *file, struct page *page,
|
||||||
up to date. */
|
up to date. */
|
||||||
if (!PageUptodate(page))
|
if (!PageUptodate(page))
|
||||||
rc = ecryptfs_do_readpage(file, page, page->index);
|
rc = ecryptfs_do_readpage(file, page, page->index);
|
||||||
pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to;
|
if (page->index != 0) {
|
||||||
if (pos > i_size_read(page->mapping->host)) {
|
loff_t end_of_prev_pg_pos =
|
||||||
rc = ecryptfs_truncate(file->f_path.dentry, pos);
|
(((loff_t)page->index << PAGE_CACHE_SHIFT) - 1);
|
||||||
if (rc) {
|
|
||||||
printk(KERN_ERR "Error on attempt to "
|
if (end_of_prev_pg_pos > i_size_read(page->mapping->host)) {
|
||||||
"truncate to (higher) offset [%lld];"
|
rc = ecryptfs_truncate(file->f_path.dentry,
|
||||||
" rc = [%d]\n", pos, rc);
|
end_of_prev_pg_pos);
|
||||||
goto out;
|
if (rc) {
|
||||||
|
printk(KERN_ERR "Error on attempt to "
|
||||||
|
"truncate to (higher) offset [%lld];"
|
||||||
|
" rc = [%d]\n", end_of_prev_pg_pos, rc);
|
||||||
|
goto out;
|
||||||
|
}
|
||||||
}
|
}
|
||||||
}
|
}
|
||||||
out:
|
out:
|
||||||
|
@ -753,7 +758,7 @@ out:
|
||||||
}
|
}
|
||||||
|
|
||||||
/**
|
/**
|
||||||
* write_zeros
|
* ecryptfs_write_zeros
|
||||||
* @file: The ecryptfs file
|
* @file: The ecryptfs file
|
||||||
* @index: The index in which we are writing
|
* @index: The index in which we are writing
|
||||||
* @start: The position after the last block of data
|
* @start: The position after the last block of data
|
||||||
|
@ -763,8 +768,8 @@ out:
|
||||||
*
|
*
|
||||||
* (start + num_zeros) must be less than or equal to PAGE_CACHE_SIZE
|
* (start + num_zeros) must be less than or equal to PAGE_CACHE_SIZE
|
||||||
*/
|
*/
|
||||||
static
|
int
|
||||||
int write_zeros(struct file *file, pgoff_t index, int start, int num_zeros)
|
ecryptfs_write_zeros(struct file *file, pgoff_t index, int start, int num_zeros)
|
||||||
{
|
{
|
||||||
int rc = 0;
|
int rc = 0;
|
||||||
struct page *tmp_page;
|
struct page *tmp_page;
|
||||||
|
|
Loading…
Reference in New Issue