linux-kernel - [PATCH 1/5] eCryptfs: convert f_op->write() to vfs

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Message-ID: <20070118212627.GC3643@us.ibm.com>
Date:	Thu, 18 Jan 2007 15:26:27 -0600
From:	Michael Halcrow <mhalcrow@...ibm.com>
To:	Andrew Morton <akpm@...l.org>
Cc:	linux-kernel@...r.kernel.org, Mike Halcrow <mhalcrow@...ibm.com>
Subject: [PATCH 1/5] eCryptfs: convert f_op->write() to vfs_write()

Andrew Morton wrote:
> On Tue, 9 Jan 2007 16:22:55 -0600
> Michael Halcrow <mhalcrow@...ibm.com> wrote:
>
> > + lower_file->f_op->write(lower_file, (char __user *)page_virt,
> > + PAGE_CACHE_SIZE, &lower_file->f_pos);
>
> hm.  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.
>
> Perhaps ecryptfs should be calling vfs_write()?
>
> That way we'd 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@...ibm.com>

---

 fs/ecryptfs/crypto.c |   27 ++++++++++++++++++++++-----
 fs/ecryptfs/inode.c  |    2 +-
 2 files changed, 23 insertions(+), 6 deletions(-)

b91d05b02335e38e18ffb87de6127b80bfe66dd7
diff --git a/fs/ecryptfs/crypto.c b/fs/ecryptfs/crypto.c
index 8fbc38c..fbb62c8 100644
--- a/fs/ecryptfs/crypto.c
+++ b/fs/ecryptfs/crypto.c
@@ -1346,24 +1346,41 @@ int ecryptfs_write_metadata_to_contents(
 	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;
 }
 
 int ecryptfs_write_metadata_to_xattr(struct dentry *ecryptfs_dentry,
diff --git a/fs/ecryptfs/inode.c b/fs/ecryptfs/inode.c
index bbc1b4f..7d33917 100644
--- a/fs/ecryptfs/inode.c
+++ b/fs/ecryptfs/inode.c
@@ -201,7 +201,7 @@ static int ecryptfs_initialize_file(stru
 			lower_dentry->d_name.name);
 	inode = ecryptfs_dentry->d_inode;
 	crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
-	lower_flags = ((O_CREAT | O_WRONLY | O_TRUNC) & O_ACCMODE) | O_RDWR;
+	lower_flags = ((O_CREAT | O_TRUNC) & O_ACCMODE) | O_RDWR;
 #if BITS_PER_LONG != 32
 	lower_flags |= O_LARGEFILE;
 #endif
-- 
1.3.3

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