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ecryptfs: fix fsx data corruption problems 

ecryptfs in 2.6.24-rc3 wasn't surviving fsx for me at all, dying after 4
ops.  Generally, encountering problems with stale data and improperly
zeroed pages.  An extending truncate + write for example would expose stale
data.

With the changes below I got to a million ops and beyond with all mmap ops
disabled - mmap still needs work.  (A version of this patch on a RHEL5
kernel ran for over 110 million fsx ops)

I added a few comments as well, to the best of my understanding
as I read through the code.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Acked-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:
Eric Sandeen 2007-12-17 16:20:10 -08:00 committed by Linus Torvalds
parent 8998979cc1
commit 7a3f595cc8
2 changed files with 41 additions and 17 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

31
fs/ecryptfs/mmap.c
View File

@ -263,14 +263,13 @@ out:
return 0;
}
/* This function must zero any hole we create */
static int ecryptfs_prepare_write(struct file *file, struct page *page,
unsigned from, unsigned to)
{
int rc = 0;
loff_t prev_page_end_size;
if (from == 0 && to == PAGE_CACHE_SIZE)
goto out; /* If we are writing a full page, it will be
up to date. */
if (!PageUptodate(page)) {
rc = ecryptfs_read_lower_page_segment(page, page->index, 0,
PAGE_CACHE_SIZE,
@ -283,22 +282,32 @@ static int ecryptfs_prepare_write(struct file *file, struct page *page,
} else
SetPageUptodate(page);
}
if (page->index != 0) {
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)) {
prev_page_end_size = ((loff_t)page->index << PAGE_CACHE_SHIFT);
/*
* If creating a page or more of holes, zero them out via truncate.
* Note, this will increase i_size.
*/
if (page->index != 0) {
if (prev_page_end_size > i_size_read(page->mapping->host)) {
rc = ecryptfs_truncate(file->f_path.dentry,
end_of_prev_pg_pos);
prev_page_end_size);
if (rc) {
printk(KERN_ERR "Error on attempt to "
"truncate to (higher) offset [%lld];"
" rc = [%d]\n", end_of_prev_pg_pos, rc);
" rc = [%d]\n", prev_page_end_size, rc);
goto out;
}
}
if (end_of_prev_pg_pos + 1 > i_size_read(page->mapping->host))
zero_user_page(page, 0, PAGE_CACHE_SIZE, KM_USER0);
}
/*
* Writing to a new page, and creating a small hole from start of page?
* Zero it out.
*/
if ((i_size_read(page->mapping->host) == prev_page_end_size) &&
(from != 0)) {
zero_user_page(page, 0, PAGE_CACHE_SIZE, KM_USER0);
}
out:
return rc;

27
fs/ecryptfs/read_write.c
View File

@ -124,6 +124,10 @@ int ecryptfs_write(struct file *ecryptfs_file, char *data, loff_t offset,
loff_t pos;
int rc = 0;
/*
* if we are writing beyond current size, then start pos
* at the current size - we'll fill in zeros from there.
*/
if (offset > ecryptfs_file_size)
pos = ecryptfs_file_size;
else
@ -137,6 +141,7 @@ int ecryptfs_write(struct file *ecryptfs_file, char *data, loff_t offset,
if (num_bytes > total_remaining_bytes)
num_bytes = total_remaining_bytes;
if (pos < offset) {
/* remaining zeros to write, up to destination offset */
size_t total_remaining_zeros = (offset - pos);
if (num_bytes > total_remaining_zeros)
@ -167,17 +172,27 @@ int ecryptfs_write(struct file *ecryptfs_file, char *data, loff_t offset,
}
}
ecryptfs_page_virt = kmap_atomic(ecryptfs_page, KM_USER0);
/*
* pos: where we're now writing, offset: where the request was
* If current pos is before request, we are filling zeros
* If we are at or beyond request, we are writing the *data*
* If we're in a fresh page beyond eof, zero it in either case
*/
if (pos < offset || !start_offset_in_page) {
/* We are extending past the previous end of the file.
* Fill in zero values to the end of the page */
memset(((char *)ecryptfs_page_virt
+ start_offset_in_page), 0,
PAGE_CACHE_SIZE - start_offset_in_page);
}
/* pos >= offset, we are now writing the data request */
if (pos >= offset) {
memcpy(((char *)ecryptfs_page_virt
+ start_offset_in_page),
(data + data_offset), num_bytes);
data_offset += num_bytes;
} else {
/* We are extending past the previous end of the file.
* Fill in zero values up to the start of where we
* will be writing data. */
memset(((char *)ecryptfs_page_virt
+ start_offset_in_page), 0, num_bytes);
}
kunmap_atomic(ecryptfs_page_virt, KM_USER0);
flush_dcache_page(ecryptfs_page);