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    SubjectRe: [PATCH v2] eCryptfs: write optimization
    On 2012-01-26 13:04:34, Li Wang wrote:
    > Hi,
    > The new version adds the code to handle short copy issue which may occure
    > in iov_iter_copy_from_user_atomic(). The idea is to let ecryptfs_write_end() return zero,
    > therefore, give iov_iter_fault_in_readable() a chance to handle the page fault
    > for the current iovec, then restart the copy operation.

    Hi Li - This approach looks like it will work. Thanks for reworking the
    patch! I've been testing it and it seems to be holding up.

    I'd like you to respin the patch one last time to fix up the commit
    message. You've gotten several eCryptfs patches in now, and I expect
    more from you in the future, so I'd like to be able to simply apply
    your patches rather than having to fix up the commit message myself.

    Keep in mind that the commit message should make sense to someone
    reading the "git log" years from now. This particular message only makes
    sense if someone looks at my review of v1 of this patch. You would want
    to put this type of text underneath the --- separator below because that
    text automatically gets stripped out when I used "git am" to apply your
    patch.

    Check out Documentation/SubmittingPatches for suggestions on writing
    good commit messages.

    >
    > Cheers,
    > Li Wang
    >
    > Signed-off-by: Li Wang <liwang@nudt.edu.cn>
    > Yunchuan Wen <wenyunchuan@kylinos.com.cn>

    You always seem to list Yunchuan. You'll need another Signed-off-by: tag
    on that line. Does Yunchuan help in the development of the patches or
    just perform review? See Documentation/development-process/5.Posting to
    identify the correct tag to use for either situation. Also, you may want
    to cc Yunchuan on these patches.

    Sorry to hold up this patch with "process" stuff, but getting the right
    commit message is important. Thanks!

    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 6a44148..b3fa499 100644
    > --- a/fs/ecryptfs/mmap.c
    > +++ b/fs/ecryptfs/mmap.c
    > @@ -346,7 +346,8 @@ 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 "
    > @@ -356,8 +357,8 @@ 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.
    > @@ -512,6 +513,13 @@ 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) {
    >
    >
    > --
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