Commit 48751b56 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'ovl-fixes-4.19-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs 

Pull overlayfs fixes from Miklos Szeredi:
 "This fixes a regression in the recent file stacking update, reported
  and fixed by Amir Goldstein. The fix is fairly trivial, but involves
  adding a fadvise() f_op and the associated churn in the vfs. As
  discussed on -fsdevel, there are other possible uses for this method,
  than allowing proper stacking for overlays.

  And there's one other fix for a syzkaller detected oops"

* tag 'ovl-fixes-4.19-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs:
  ovl: fix oopses in ovl_fill_super() failure paths
  ovl: add ovl_fadvise()
  vfs: implement readahead(2) using POSIX_FADV_WILLNEED
  vfs: add the fadvise() file operation
  Documentation/filesystems: update documentation of file_operations
  ovl: fix GPF in swapfile_activate of file from overlayfs over xfs
  ovl: respect FIEMAP_FLAG_SYNC flag
parents 4d8d9f54 8c25741a

Documentation/filesystems/vfs.txt

+19 −2
Original line number Diff line number Diff line
@@ -848,7 +848,7 @@ struct file_operations 
----------------------



This describes how the VFS can manipulate an open file. As of kernel

4.1, the following members are defined:

4.18, the following members are defined:



struct file_operations {

	struct module *owner;
@@ -858,11 +858,11 @@ struct file_operations { 
	ssize_t (*read_iter) (struct kiocb *, struct iov_iter *);

	ssize_t (*write_iter) (struct kiocb *, struct iov_iter *);

	int (*iterate) (struct file *, struct dir_context *);

	int (*iterate_shared) (struct file *, struct dir_context *);

	__poll_t (*poll) (struct file *, struct poll_table_struct *);

	long (*unlocked_ioctl) (struct file *, unsigned int, unsigned long);

	long (*compat_ioctl) (struct file *, unsigned int, unsigned long);

	int (*mmap) (struct file *, struct vm_area_struct *);

	int (*mremap)(struct file *, struct vm_area_struct *);

	int (*open) (struct inode *, struct file *);

	int (*flush) (struct file *, fl_owner_t id);

	int (*release) (struct inode *, struct file *);
@@ -882,6 +882,10 @@ struct file_operations { 
#ifndef CONFIG_MMU

	unsigned (*mmap_capabilities)(struct file *);

#endif

	ssize_t (*copy_file_range)(struct file *, loff_t, struct file *, loff_t, size_t, unsigned int);

	int (*clone_file_range)(struct file *, loff_t, struct file *, loff_t, u64);

	int (*dedupe_file_range)(struct file *, loff_t, struct file *, loff_t, u64);

	int (*fadvise)(struct file *, loff_t, loff_t, int);

};



Again, all methods are called without any locks being held, unless
@@ -899,6 +903,9 @@ otherwise noted. 


  iterate: called when the VFS needs to read the directory contents



  iterate_shared: called when the VFS needs to read the directory contents

	when filesystem supports concurrent dir iterators



  poll: called by the VFS when a process wants to check if there is

	activity on this file and (optionally) go to sleep until there

	is activity. Called by the select(2) and poll(2) system calls
@@ -951,6 +958,16 @@ otherwise noted. 


  fallocate: called by the VFS to preallocate blocks or punch a hole.



  copy_file_range: called by the copy_file_range(2) system call.



  clone_file_range: called by the ioctl(2) system call for FICLONERANGE and

	FICLONE commands.



  dedupe_file_range: called by the ioctl(2) system call for FIDEDUPERANGE

	command.



  fadvise: possibly called by the fadvise64() system call.



Note that the file operations are implemented by the specific

filesystem in which the inode resides. When opening a device node

(character or block special) most filesystems will call special

fs/overlayfs/file.c

+20 −3
Original line number Diff line number Diff line
@@ -131,9 +131,6 @@ static int ovl_open(struct inode *inode, struct file *file) 
	if (IS_ERR(realfile))

		return PTR_ERR(realfile);



	/* For O_DIRECT dentry_open() checks f_mapping->a_ops->direct_IO */

	file->f_mapping = realfile->f_mapping;



	file->private_data = realfile;



	return 0;
@@ -334,6 +331,25 @@ static long ovl_fallocate(struct file *file, int mode, loff_t offset, loff_t len 
	return ret;

}



static int ovl_fadvise(struct file *file, loff_t offset, loff_t len, int advice)

{

	struct fd real;

	const struct cred *old_cred;

	int ret;



	ret = ovl_real_fdget(file, &real);

	if (ret)

		return ret;



	old_cred = ovl_override_creds(file_inode(file)->i_sb);

	ret = vfs_fadvise(real.file, offset, len, advice);

	revert_creds(old_cred);



	fdput(real);



	return ret;

}



static long ovl_real_ioctl(struct file *file, unsigned int cmd,

			   unsigned long arg)

{
@@ -502,6 +518,7 @@ const struct file_operations ovl_file_operations = { 
	.fsync		= ovl_fsync,

	.mmap		= ovl_mmap,

	.fallocate	= ovl_fallocate,

	.fadvise	= ovl_fadvise,

	.unlocked_ioctl	= ovl_ioctl,

	.compat_ioctl	= ovl_compat_ioctl,

fs/overlayfs/inode.c

+10 −0
Original line number Diff line number Diff line
@@ -467,6 +467,10 @@ static int ovl_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo, 
		return -EOPNOTSUPP;



	old_cred = ovl_override_creds(inode->i_sb);



	if (fieinfo->fi_flags & FIEMAP_FLAG_SYNC)

		filemap_write_and_wait(realinode->i_mapping);



	err = realinode->i_op->fiemap(realinode, fieinfo, start, len);

	revert_creds(old_cred);
@@ -500,6 +504,11 @@ static const struct inode_operations ovl_special_inode_operations = { 
	.update_time	= ovl_update_time,

};



const struct address_space_operations ovl_aops = {

	/* For O_DIRECT dentry_open() checks f_mapping->a_ops->direct_IO */

	.direct_IO		= noop_direct_IO,

};



/*

 * It is possible to stack overlayfs instance on top of another

 * overlayfs instance as lower layer. We need to annonate the
@@ -571,6 +580,7 @@ static void ovl_fill_inode(struct inode *inode, umode_t mode, dev_t rdev, 
	case S_IFREG:

		inode->i_op = &ovl_file_inode_operations;

		inode->i_fop = &ovl_file_operations;

		inode->i_mapping->a_ops = &ovl_aops;

		break;



	case S_IFDIR:

fs/overlayfs/super.c

+14 −12
Original line number Diff line number Diff line
@@ -982,16 +982,6 @@ static int ovl_get_upper(struct ovl_fs *ofs, struct path *upperpath) 
	if (err)

		goto out;



	err = -EBUSY;

	if (ovl_inuse_trylock(upperpath->dentry)) {

		ofs->upperdir_locked = true;

	} else if (ofs->config.index) {

		pr_err("overlayfs: upperdir is in-use by another mount, mount with '-o index=off' to override exclusive upperdir protection.\n");

		goto out;

	} else {

		pr_warn("overlayfs: upperdir is in-use by another mount, accessing files from both mounts will result in undefined behavior.\n");

	}



	upper_mnt = clone_private_mount(upperpath);

	err = PTR_ERR(upper_mnt);

	if (IS_ERR(upper_mnt)) {
@@ -1002,6 +992,17 @@ static int ovl_get_upper(struct ovl_fs *ofs, struct path *upperpath) 
	/* Don't inherit atime flags */

	upper_mnt->mnt_flags &= ~(MNT_NOATIME | MNT_NODIRATIME | MNT_RELATIME);

	ofs->upper_mnt = upper_mnt;



	err = -EBUSY;

	if (ovl_inuse_trylock(ofs->upper_mnt->mnt_root)) {

		ofs->upperdir_locked = true;

	} else if (ofs->config.index) {

		pr_err("overlayfs: upperdir is in-use by another mount, mount with '-o index=off' to override exclusive upperdir protection.\n");

		goto out;

	} else {

		pr_warn("overlayfs: upperdir is in-use by another mount, accessing files from both mounts will result in undefined behavior.\n");

	}



	err = 0;

out:

	return err;
@@ -1101,8 +1102,10 @@ static int ovl_get_workdir(struct ovl_fs *ofs, struct path *upperpath) 
		goto out;

	}



	ofs->workbasedir = dget(workpath.dentry);



	err = -EBUSY;

	if (ovl_inuse_trylock(workpath.dentry)) {

	if (ovl_inuse_trylock(ofs->workbasedir)) {

		ofs->workdir_locked = true;

	} else if (ofs->config.index) {

		pr_err("overlayfs: workdir is in-use by another mount, mount with '-o index=off' to override exclusive workdir protection.\n");
@@ -1111,7 +1114,6 @@ static int ovl_get_workdir(struct ovl_fs *ofs, struct path *upperpath) 
		pr_warn("overlayfs: workdir is in-use by another mount, accessing files from both mounts will result in undefined behavior.\n");

	}



	ofs->workbasedir = dget(workpath.dentry);

	err = ovl_make_workdir(ofs, &workpath);

	if (err)

		goto out;

include/linux/fs.h

+5 −0
Original line number Diff line number Diff line
@@ -1763,6 +1763,7 @@ struct file_operations { 
			u64);

	int (*dedupe_file_range)(struct file *, loff_t, struct file *, loff_t,

			u64);

	int (*fadvise)(struct file *, loff_t, loff_t, int);

} __randomize_layout;



struct inode_operations {
@@ -3459,4 +3460,8 @@ static inline bool dir_relax_shared(struct inode *inode) 
extern bool path_noexec(const struct path *path);

extern void inode_nohighmem(struct inode *inode);



/* mm/fadvise.c */

extern int vfs_fadvise(struct file *file, loff_t offset, loff_t len,

		       int advice);



#endif /* _LINUX_FS_H */

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