[PATCH] eCryptfs: convert f_op->write() to vfs_write()

sys_write() takes a local copy of f_pos and writes that back
into the struct file. It does this so that two concurrent write()
callers don't make a mess of f_pos, and of the file contents.

ecryptfs should be calling vfs_write().  That way we also get the fsnotify
notifications, which ecryptfs presently appears to have subverted.

Convert direct calls to f_op->write() into calls to vfs_write().

Signed-off-by: Michael Halcrow <mhalcrow@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 22 insertions, 5 deletions

diff --git a/fs/ecryptfs/crypto.c b/fs/ecryptfs/crypto.c
index 44c2ec2e9e6a..2d7db61b9d6c 100644
--- a/fs/ecryptfs/crypto.c
+++ b/fs/ecryptfs/crypto.c
@@ -1344,24 +1344,41 @@ static int ecryptfs_write_metadata_to_contents(struct ecryptfs_crypt_stat *crypt
         mm_segment_t oldfs;
         int current_header_page;
         int header_pages;
+        ssize_t size;
+        int rc = 0;
 
         lower_file->f_pos = 0;
         oldfs = get_fs();
         set_fs(get_ds());
-        lower_file->f_op->write(lower_file, (char __user *)page_virt,
-                                PAGE_CACHE_SIZE, &lower_file->f_pos);
+        size = vfs_write(lower_file, (char __user *)page_virt, PAGE_CACHE_SIZE,
+                         &lower_file->f_pos);
+        if (size < 0) {
+                rc = (int)size;
+                printk(KERN_ERR "Error attempting to write lower page; "
+                       "rc = [%d]\n", rc);
+                set_fs(oldfs);
+                goto out;
+        }
         header_pages = ((crypt_stat->header_extent_size
                          * crypt_stat->num_header_extents_at_front)
                         / PAGE_CACHE_SIZE);
         memset(page_virt, 0, PAGE_CACHE_SIZE);
         current_header_page = 1;
         while (current_header_page < header_pages) {
-                lower_file->f_op->write(lower_file, (char __user *)page_virt,
-                                        PAGE_CACHE_SIZE, &lower_file->f_pos);
+                size = vfs_write(lower_file, (char __user *)page_virt,
+                                 PAGE_CACHE_SIZE, &lower_file->f_pos);
+                if (size < 0) {
+                        rc = (int)size;
+                        printk(KERN_ERR "Error attempting to write lower page; "
+                               "rc = [%d]\n", rc);
+                        set_fs(oldfs);
+                        goto out;
+                }
                 current_header_page++;
         }
         set_fs(oldfs);
-        return 0;
+out:
+        return rc;
 }
 
 static int ecryptfs_write_metadata_to_xattr(struct dentry *ecryptfs_dentry,