On 2012-10-30 19:52:40, Li Wang wrote:
> ecryptfs_write_begin grabs a page from page cache for writing.
> If the page contains invalid data, or data older than the
> counterpart on the disk, eCryptfs will read out the
> corresponing data from the disk into the page, decrypt them,
> then perform writing. However, for this page, if the length
> of the data to be written into is equal to page size,
> that means the whole page of data will be overwritten,
> in which case, it does not matter whatever the data were before,
> it is beneficial to perform writing directly rather than bothering
> to read and decrypt first.
>
> With this optimization, according to our test on a machine with
> Intel Core 2 Duo processor, iozone 'write' operation on an existing
> file with write size being multiple of page size will enjoy a steady
> 3x speedup.
>
> Signed-off-by: Li Wang <wangli@xxxxxxxxxxxxxx>
> Signed-off-by: Yunchuan Wen <wenyunchuan@xxxxxxxxxxxxxx>
> Reviewed-by: Tyler Hicks <tyhicks@xxxxxxxxxxxxx>
Thanks again, Li. I've pushed this to my next branch.
I lost track of it last time. Sorry about that!
Tyler
> ---
> fs/ecryptfs/mmap.c | 12 ++++++++++--
> 1 files changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/fs/ecryptfs/mmap.c b/fs/ecryptfs/mmap.c
> index bd1d57f..564a1fa 100644
> --- a/fs/ecryptfs/mmap.c
> +++ b/fs/ecryptfs/mmap.c
> @@ -338,7 +338,8 @@ static int ecryptfs_write_begin(struct file *file,
> if (prev_page_end_size
> >= i_size_read(page->mapping->host)) {
> zero_user(page, 0, PAGE_CACHE_SIZE);
> - } else {
> + SetPageUptodate(page);
> + } else if (len < PAGE_CACHE_SIZE) {
> rc = ecryptfs_decrypt_page(page);
> if (rc) {
> printk(KERN_ERR "%s: Error decrypting "
> @@ -348,8 +349,8 @@ static int ecryptfs_write_begin(struct file *file,
> ClearPageUptodate(page);
> goto out;
> }
> + SetPageUptodate(page);
> }
> - SetPageUptodate(page);
> }
> }
> /* If creating a page or more of holes, zero them out via truncate.
> @@ -499,6 +500,13 @@ static int ecryptfs_write_end(struct file *file,
> }
> goto out;
> }
> + if (!PageUptodate(page)) {
> + if (copied < PAGE_CACHE_SIZE) {
> + rc = 0;
> + goto out;
> + }
> + SetPageUptodate(page);
> + }
> /* Fills in zeros if 'to' goes beyond inode size */
> rc = fill_zeros_to_end_of_page(page, to);
> if (rc) {
> --
> 1.7.6.5
>
> --
> To unsubscribe from this list: send the line "unsubscribe ecryptfs" in
> the body of a message to majordomo@xxxxxxxxxxxxxxx
> More majordomo info at http://vger.kernel.org/majordomo-info.html
Attachment:
signature.asc
Description: Digital signature
