vfs: splice remove_suid() cleanup

generic_file_splice_write() duplicates remove_suid() just because it
doesn't hold i_mutex.  But it grabs i_mutex inside splice_from_pipe()
anyway, so this is rather pointless.

Move locking to generic_file_splice_write() and call remove_suid() and
__splice_from_pipe() instead.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

diff --git a/fs/splice.c b/fs/splice.c
index 633f58e..cece15b 100644 (file)
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -811,24 +811,19 @@ generic_file_splice_write(struct pipe_inode_info *pipe, struct file *out,
 {
        struct address_space *mapping = out->f_mapping;
        struct inode *inode = mapping->host;
-       int killsuid, killpriv;
+       struct splice_desc sd = {
+               .total_len = len,
+               .flags = flags,
+               .pos = *ppos,
+               .u.file = out,
+       };
        ssize_t ret;
-       int err = 0;
-
-       killpriv = security_inode_need_killpriv(out->f_path.dentry);
-       killsuid = should_remove_suid(out->f_path.dentry);
-       if (unlikely(killsuid || killpriv)) {
-               mutex_lock(&inode->i_mutex);
-               if (killpriv)
-                       err = security_inode_killpriv(out->f_path.dentry);
-               if (!err && killsuid)
-                       err = __remove_suid(out->f_path.dentry, killsuid);
-               mutex_unlock(&inode->i_mutex);
-               if (err)
-                       return err;
-       }
 
-       ret = splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_file);
+       inode_double_lock(inode, pipe->inode);
+       ret = remove_suid(out->f_path.dentry);
+       if (likely(!ret))
+               ret = __splice_from_pipe(pipe, &sd, pipe_to_file);
+       inode_double_unlock(inode, pipe->inode);
        if (ret > 0) {
                unsigned long nr_pages;
 
@@ -840,6 +835,8 @@ generic_file_splice_write(struct pipe_inode_info *pipe, struct file *out,
                 * sync it.
                 */
                if (unlikely((out->f_flags & O_SYNC) || IS_SYNC(inode))) {
+                       int err;
+
                        mutex_lock(&inode->i_mutex);
                        err = generic_osync_inode(inode, mapping,
                                                  OSYNC_METADATA|OSYNC_DATA);

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 7e0fa9e..f413085 100644 (file)
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1816,7 +1816,6 @@ extern void iget_failed(struct inode *);
 extern void clear_inode(struct inode *);
 extern void destroy_inode(struct inode *);
 extern struct inode *new_inode(struct super_block *);
-extern int __remove_suid(struct dentry *, int);
 extern int should_remove_suid(struct dentry *);
 extern int remove_suid(struct dentry *);
 

diff --git a/mm/filemap.c b/mm/filemap.c
index 239d361..2dead9a 100644 (file)
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1655,7 +1655,7 @@ int should_remove_suid(struct dentry *dentry)
 }
 EXPORT_SYMBOL(should_remove_suid);
 
-int __remove_suid(struct dentry *dentry, int kill)
+static int __remove_suid(struct dentry *dentry, int kill)
 {
        struct iattr newattrs;