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Subject[PATCH v2] eCryptfs: write optimization
Date
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.

Cheers,
Li Wang

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

---

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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