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-rw-r--r--fs/open.c52
1 files changed, 35 insertions, 17 deletions
diff --git a/fs/open.c b/fs/open.c
index 54723fceb7..3494a9cd80 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -870,6 +870,30 @@ SYSCALL_DEFINE3(fchown, unsigned int, fd, uid_t, user, gid_t, group)
return ksys_fchown(fd, user, group);
}
+static inline int file_get_write_access(struct file *f)
+{
+ int error;
+
+ error = get_write_access(f->f_inode);
+ if (unlikely(error))
+ return error;
+ error = mnt_get_write_access(f->f_path.mnt);
+ if (unlikely(error))
+ goto cleanup_inode;
+ if (unlikely(f->f_mode & FMODE_BACKING)) {
+ error = mnt_get_write_access(backing_file_user_path(f)->mnt);
+ if (unlikely(error))
+ goto cleanup_mnt;
+ }
+ return 0;
+
+cleanup_mnt:
+ mnt_put_write_access(f->f_path.mnt);
+cleanup_inode:
+ put_write_access(f->f_inode);
+ return error;
+}
+
static int do_dentry_open(struct file *f,
struct inode *inode,
int (*open)(struct inode *, struct file *))
@@ -892,14 +916,9 @@ static int do_dentry_open(struct file *f,
if ((f->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ) {
i_readcount_inc(inode);
} else if (f->f_mode & FMODE_WRITE && !special_file(inode->i_mode)) {
- error = get_write_access(inode);
+ error = file_get_write_access(f);
if (unlikely(error))
goto cleanup_file;
- error = __mnt_want_write(f->f_path.mnt);
- if (unlikely(error)) {
- put_write_access(inode);
- goto cleanup_file;
- }
f->f_mode |= FMODE_WRITER;
}
@@ -1160,20 +1179,19 @@ EXPORT_SYMBOL_GPL(kernel_file_open);
/**
* backing_file_open - open a backing file for kernel internal use
- * @path: path of the file to open
+ * @user_path: path that the user reuqested to open
* @flags: open flags
* @real_path: path of the backing file
* @cred: credentials for open
*
* Open a backing file for a stackable filesystem (e.g., overlayfs).
- * @path may be on the stackable filesystem and backing inode on the
- * underlying filesystem. In this case, we want to be able to return
- * the @real_path of the backing inode. This is done by embedding the
- * returned file into a container structure that also stores the path of
- * the backing inode on the underlying filesystem, which can be
- * retrieved using backing_file_real_path().
+ * @user_path may be on the stackable filesystem and @real_path on the
+ * underlying filesystem. In this case, we want to be able to return the
+ * @user_path of the stackable filesystem. This is done by embedding the
+ * returned file into a container structure that also stores the stacked
+ * file's path, which can be retrieved using backing_file_user_path().
*/
-struct file *backing_file_open(const struct path *path, int flags,
+struct file *backing_file_open(const struct path *user_path, int flags,
const struct path *real_path,
const struct cred *cred)
{
@@ -1184,9 +1202,9 @@ struct file *backing_file_open(const struct path *path, int flags,
if (IS_ERR(f))
return f;
- f->f_path = *path;
- path_get(real_path);
- *backing_file_real_path(f) = *real_path;
+ path_get(user_path);
+ *backing_file_user_path(f) = *user_path;
+ f->f_path = *real_path;
error = do_dentry_open(f, d_inode(real_path->dentry), NULL);
if (error) {
fput(f);