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Commit dd20908a authored by Al Viro's avatar Al Viro
Browse files

don't bother with {get,put}_write_access() on non-regular files 



it's pointless and actually leads to wrong behaviour in at least one
moderately convoluted case (pipe(), close one end, try to get to
another via /proc/*/fd and run into ETXTBUSY).

Cc: stable@vger.kernel.org
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 44ba8406

fs/file_table.c

+2 −2
Original line number Diff line number Diff line
@@ -209,10 +209,10 @@ static void drop_file_write_access(struct file *file) 
	struct dentry *dentry = file->f_path.dentry;

	struct inode *inode = dentry->d_inode;



	put_write_access(inode);



	if (special_file(inode->i_mode))

		return;



	put_write_access(inode);

	if (file_check_writeable(file) != 0)

		return;

	__mnt_drop_write(mnt);

fs/open.c

+7 −19
Original line number Diff line number Diff line
@@ -641,23 +641,12 @@ SYSCALL_DEFINE3(fchown, unsigned int, fd, uid_t, user, gid_t, group) 
static inline int __get_file_write_access(struct inode *inode,

					  struct vfsmount *mnt)

{

	int error;

	error = get_write_access(inode);

	int error = get_write_access(inode);

	if (error)

		return error;

	/*

	 * Do not take mount writer counts on

	 * special files since no writes to

	 * the mount itself will occur.

	 */

	if (!special_file(inode->i_mode)) {

		/*

		 * Balanced in __fput()

		 */

	error = __mnt_want_write(mnt);

	if (error)

		put_write_access(inode);

	}

	return error;

}
@@ -690,11 +679,10 @@ static int do_dentry_open(struct file *f, 


	path_get(&f->f_path);

	inode = f->f_inode = f->f_path.dentry->d_inode;

	if (f->f_mode & FMODE_WRITE) {

	if (f->f_mode & FMODE_WRITE && !special_file(inode->i_mode)) {

		error = __get_file_write_access(inode, f->f_path.mnt);

		if (error)

			goto cleanup_file;

		if (!special_file(inode->i_mode))

		file_take_write(f);

	}
@@ -742,7 +730,6 @@ static int do_dentry_open(struct file *f, 
cleanup_all:

	fops_put(f->f_op);

	if (f->f_mode & FMODE_WRITE) {

		put_write_access(inode);

		if (!special_file(inode->i_mode)) {

			/*

			 * We don't consider this a real
@@ -750,6 +737,7 @@ static int do_dentry_open(struct file *f, 
			 * because it all happenend right

			 * here, so just reset the state.

			 */

			put_write_access(inode);

			file_reset_write(f);

			__mnt_drop_write(f->f_path.mnt);

		}