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ecryptfs: fix fsx data corruption problems

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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
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31
fs/ecryptfs/mmap.c
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@@ -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;