Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 7a3f595c authored by Eric Sandeen's avatar Eric Sandeen Committed by Linus Torvalds
Browse files

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: default avatarEric Sandeen <sandeen@redhat.com>
Acked-by: default avatarMichael Halcrow <mhalcrow@us.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 8998979c

fs/ecryptfs/mmap.c

+20 −11
Original line number Diff line number Diff line
@@ -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,
@@ -283,21 +282,31 @@ 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))

	}

	/*

	 * 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:

fs/ecryptfs/read_write.c

+21 −6
Original line number Diff line number Diff line
@@ -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);