From: Tyler Hicks <tyhicks@canonical.com>

Since eCryptfs only calls fput() on the lower file in
ecryptfs_release(), eCryptfs should call the lower filesystem's
->flush() from ecryptfs_flush().

If the lower filesystem implements ->flush(), then eCryptfs should try
to flush out any dirty pages prior to calling the lower ->flush(). If
the lower filesystem does not implement ->flush(), then eCryptfs has no
need to do anything in ecryptfs_flush() since dirty pages are now
written out to the lower filesystem in ecryptfs_release().

BugLink: https://launchpad.net/bugs/1047261

Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
(upstream cherry pick 64e6651dcc10e9d2cc6230208a8e6c2cfd19ae18)
Colin Ian King <colin.king@canonical.com>
---
fs/ecryptfs/file.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/fs/ecryptfs/file.c b/fs/ecryptfs/file.c
index 44ce5c6..d45ba45 100644
--- a/fs/ecryptfs/file.c
+++ b/fs/ecryptfs/file.c
@@ -275,8 +275,14 @@ out:

static int ecryptfs_flush(struct file *file, fl_owner_t td)
{
- return file->f_mode & FMODE_WRITE
- ? filemap_write_and_wait(file->f_mapping) : 0;
+ struct file *lower_file = ecryptfs_file_to_lower(file);
+
+ if (lower_file->f_op && lower_file->f_op->flush) {
+ filemap_write_and_wait(file->f_mapping);
+ return lower_file->f_op->flush(lower_file, td);
+ }
+
+ return 0;
}

static int ecryptfs_release(struct inode *inode, struct file *file)
--
1.7.10.4


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