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eCryptfs: convert mmap functions to use persistent file
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Convert readpage, prepare_write, and commit_write to use read_write.c
routines.  Remove sync_page; I cannot think of a good reason for implementing
that in eCryptfs.

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>
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Michael Halcrow authored and Linus Torvalds committed Oct 16, 2007
1 parent 2ed9255 commit bf12be1
Showing 1 changed file with 103 additions and 96 deletions.
199 changes: 103 additions & 96 deletions fs/ecryptfs/mmap.c
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Original file line number Diff line number Diff line change
Expand Up @@ -266,70 +266,115 @@ static void set_header_info(char *page_virt,
save_num_header_extents_at_front;
}

/**
* ecryptfs_copy_up_encrypted_with_header
* @page: Sort of a ``virtual'' representation of the encrypted lower
* file. The actual lower file does not have the metadata in
* the header. This is locked.
* @crypt_stat: The eCryptfs inode's cryptographic context
*
* The ``view'' is the version of the file that userspace winds up
* seeing, with the header information inserted.
*/
static int
ecryptfs_copy_up_encrypted_with_header(struct page *page,
struct ecryptfs_crypt_stat *crypt_stat)
{
loff_t extent_num_in_page = 0;
loff_t num_extents_per_page = (PAGE_CACHE_SIZE
/ crypt_stat->extent_size);
int rc = 0;

while (extent_num_in_page < num_extents_per_page) {
loff_t view_extent_num = ((page->index * num_extents_per_page)
+ extent_num_in_page);

if (view_extent_num < crypt_stat->num_header_extents_at_front) {
/* This is a header extent */
char *page_virt;

page_virt = kmap_atomic(page, KM_USER0);
memset(page_virt, 0, PAGE_CACHE_SIZE);
/* TODO: Support more than one header extent */
if (view_extent_num == 0) {
rc = ecryptfs_read_xattr_region(
page_virt, page->mapping->host);
set_header_info(page_virt, crypt_stat);
}
kunmap_atomic(page_virt, KM_USER0);
flush_dcache_page(page);
if (rc) {
ClearPageUptodate(page);
printk(KERN_ERR "%s: Error reading xattr "
"region; rc = [%d]\n", __FUNCTION__, rc);
goto out;
}
SetPageUptodate(page);
} else {
/* This is an encrypted data extent */
loff_t lower_offset =
((view_extent_num -
crypt_stat->num_header_extents_at_front)
* crypt_stat->extent_size);

rc = ecryptfs_read_lower_page_segment(
page, (lower_offset >> PAGE_CACHE_SHIFT),
(lower_offset & ~PAGE_CACHE_MASK),
crypt_stat->extent_size, page->mapping->host);
if (rc) {
printk(KERN_ERR "%s: Error attempting to read "
"extent at offset [%lld] in the lower "
"file; rc = [%d]\n", __FUNCTION__,
lower_offset, rc);
goto out;
}
}
extent_num_in_page++;
}
out:
return rc;
}

/**
* ecryptfs_readpage
* @file: This is an ecryptfs file
* @page: ecryptfs associated page to stick the read data into
* @file: An eCryptfs file
* @page: Page from eCryptfs inode mapping into which to stick the read data
*
* Read in a page, decrypting if necessary.
*
* Returns zero on success; non-zero on error.
*/
static int ecryptfs_readpage(struct file *file, struct page *page)
{
struct ecryptfs_crypt_stat *crypt_stat =
&ecryptfs_inode_to_private(file->f_path.dentry->d_inode)->crypt_stat;
int rc = 0;
struct ecryptfs_crypt_stat *crypt_stat;

BUG_ON(!(file && file->f_path.dentry && file->f_path.dentry->d_inode));
crypt_stat = &ecryptfs_inode_to_private(file->f_path.dentry->d_inode)
->crypt_stat;
if (!crypt_stat
|| !(crypt_stat->flags & ECRYPTFS_ENCRYPTED)
|| (crypt_stat->flags & ECRYPTFS_NEW_FILE)) {
ecryptfs_printk(KERN_DEBUG,
"Passing through unencrypted page\n");
rc = ecryptfs_do_readpage(file, page, page->index);
if (rc) {
ecryptfs_printk(KERN_ERR, "Error reading page; rc = "
"[%d]\n", rc);
goto out;
}
rc = ecryptfs_read_lower_page_segment(page, page->index, 0,
PAGE_CACHE_SIZE,
page->mapping->host);
} else if (crypt_stat->flags & ECRYPTFS_VIEW_AS_ENCRYPTED) {
if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR) {
int num_pages_in_header_region =
(crypt_stat->extent_size
/ PAGE_CACHE_SIZE);

if (page->index < num_pages_in_header_region) {
char *page_virt;

page_virt = kmap_atomic(page, KM_USER0);
memset(page_virt, 0, PAGE_CACHE_SIZE);
if (page->index == 0) {
rc = ecryptfs_read_xattr_region(
page_virt, page->mapping->host);
set_header_info(page_virt, crypt_stat);
}
kunmap_atomic(page_virt, KM_USER0);
flush_dcache_page(page);
if (rc) {
printk(KERN_ERR "Error reading xattr "
"region\n");
goto out;
}
} else {
rc = ecryptfs_do_readpage(
file, page,
(page->index
- num_pages_in_header_region));
if (rc) {
printk(KERN_ERR "Error reading page; "
"rc = [%d]\n", rc);
goto out;
}
rc = ecryptfs_copy_up_encrypted_with_header(page,
crypt_stat);
if (rc) {
printk(KERN_ERR "%s: Error attempting to copy "
"the encrypted content from the lower "
"file whilst inserting the metadata "
"from the xattr into the header; rc = "
"[%d]\n", __FUNCTION__, rc);
goto out;
}

} else {
rc = ecryptfs_do_readpage(file, page, page->index);
rc = ecryptfs_read_lower_page_segment(
page, page->index, 0, PAGE_CACHE_SIZE,
page->mapping->host);
if (rc) {
printk(KERN_ERR "Error reading page; rc = "
"[%d]\n", rc);
Expand All @@ -344,10 +389,7 @@ static int ecryptfs_readpage(struct file *file, struct page *page)
goto out;
}
}
SetPageUptodate(page);
out:
if (rc)
ClearPageUptodate(page);
ecryptfs_printk(KERN_DEBUG, "Unlocking page with index = [0x%.16x]\n",
page->index);
unlock_page(page);
Expand Down Expand Up @@ -403,9 +445,12 @@ static int ecryptfs_prepare_write(struct file *file, struct page *page,
goto out; /* If we are writing a full page, it will be
up to date. */
if (!PageUptodate(page))
rc = ecryptfs_do_readpage(file, page, page->index);
rc = ecryptfs_read_lower_page_segment(page, page->index, 0,
PAGE_CACHE_SIZE,
page->mapping->host);
if (page->index != 0) {
loff_t end_of_prev_pg_pos = page_offset(page) - 1;
loff_t end_of_prev_pg_pos =
(((loff_t)page->index << PAGE_CACHE_SHIFT) - 1);

if (end_of_prev_pg_pos > i_size_read(page->mapping->host)) {
rc = ecryptfs_truncate(file->f_path.dentry,
Expand Down Expand Up @@ -633,18 +678,11 @@ static int ecryptfs_commit_write(struct file *file, struct page *page,
unsigned from, unsigned to)
{
loff_t pos;
struct inode *inode;
struct inode *lower_inode;
struct file *lower_file;
struct ecryptfs_crypt_stat *crypt_stat;
struct inode *ecryptfs_inode = page->mapping->host;
struct ecryptfs_crypt_stat *crypt_stat =
&ecryptfs_inode_to_private(file->f_path.dentry->d_inode)->crypt_stat;
int rc;

inode = page->mapping->host;
lower_inode = ecryptfs_inode_to_lower(inode);
lower_file = ecryptfs_file_to_lower(file);
mutex_lock(&lower_inode->i_mutex);
crypt_stat = &ecryptfs_inode_to_private(file->f_path.dentry->d_inode)
->crypt_stat;
if (crypt_stat->flags & ECRYPTFS_NEW_FILE) {
ecryptfs_printk(KERN_DEBUG, "ECRYPTFS_NEW_FILE flag set in "
"crypt_stat at memory location [%p]\n", crypt_stat);
Expand All @@ -654,6 +692,7 @@ static int ecryptfs_commit_write(struct file *file, struct page *page,
ecryptfs_printk(KERN_DEBUG, "Calling fill_zeros_to_end_of_page"
"(page w/ index = [0x%.16x], to = [%d])\n", page->index,
to);
/* Fills in zeros if 'to' goes beyond inode size */
rc = fill_zeros_to_end_of_page(page, to);
if (rc) {
ecryptfs_printk(KERN_WARNING, "Error attempting to fill "
Expand All @@ -667,25 +706,17 @@ static int ecryptfs_commit_write(struct file *file, struct page *page,
"index [0x%.16x])\n", page->index);
goto out;
}
inode->i_blocks = lower_inode->i_blocks;
pos = page_offset(page) + to;
if (pos > i_size_read(inode)) {
i_size_write(inode, pos);
pos = (page->index << PAGE_CACHE_SHIFT) + to;
if (pos > i_size_read(ecryptfs_inode)) {
i_size_write(ecryptfs_inode, pos);
ecryptfs_printk(KERN_DEBUG, "Expanded file size to "
"[0x%.16x]\n", i_size_read(inode));
"[0x%.16x]\n", i_size_read(ecryptfs_inode));
}
rc = ecryptfs_write_inode_size_to_metadata(inode);
rc = ecryptfs_write_inode_size_to_metadata(ecryptfs_inode);
if (rc)
printk(KERN_ERR "Error writing inode size to metadata; "
"rc = [%d]\n", rc);
lower_inode->i_mtime = lower_inode->i_ctime = CURRENT_TIME;
mark_inode_dirty_sync(inode);
out:
if (rc < 0)
ClearPageUptodate(page);
else
SetPageUptodate(page);
mutex_unlock(&lower_inode->i_mutex);
return rc;
}

Expand Down Expand Up @@ -751,34 +782,10 @@ static sector_t ecryptfs_bmap(struct address_space *mapping, sector_t block)
return rc;
}

static void ecryptfs_sync_page(struct page *page)
{
struct inode *inode;
struct inode *lower_inode;
struct page *lower_page;

inode = page->mapping->host;
lower_inode = ecryptfs_inode_to_lower(inode);
/* NOTE: Recently swapped with grab_cache_page(), since
* sync_page() just makes sure that pending I/O gets done. */
lower_page = find_lock_page(lower_inode->i_mapping, page->index);
if (!lower_page) {
ecryptfs_printk(KERN_DEBUG, "find_lock_page failed\n");
return;
}
if (lower_page->mapping->a_ops->sync_page)
lower_page->mapping->a_ops->sync_page(lower_page);
ecryptfs_printk(KERN_DEBUG, "Unlocking page with index = [0x%.16x]\n",
lower_page->index);
unlock_page(lower_page);
page_cache_release(lower_page);
}

struct address_space_operations ecryptfs_aops = {
.writepage = ecryptfs_writepage,
.readpage = ecryptfs_readpage,
.prepare_write = ecryptfs_prepare_write,
.commit_write = ecryptfs_commit_write,
.bmap = ecryptfs_bmap,
.sync_page = ecryptfs_sync_page,
};

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