Commit d652502e authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'ovl-update-5.13' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs 

Pull overlayfs update from Miklos Szeredi:

 - Fix a regression introduced in 5.2 that resulted in valid overlayfs
   mounts being rejected with ELOOP (Too many levels of symbolic links)

 - Fix bugs found by various tools

 - Miscellaneous improvements and cleanups

* tag 'ovl-update-5.13' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs:
  ovl: add debug print to ovl_do_getxattr()
  ovl: invalidate readdir cache on changes to dir with origin
  ovl: allow upperdir inside lowerdir
  ovl: show "userxattr" in the mount data
  ovl: trivial typo fixes in the file inode.c
  ovl: fix misspellings using codespell tool
  ovl: do not copy attr several times
  ovl: remove ovl_map_dev_ino() return value
  ovl: fix error for ovl_fill_super()
  ovl: fix missing revert_creds() on error path
  ovl: fix leaked dentry
  ovl: restrict lower null uuid for "xino=auto"
  ovl: check that upperdir path is not on a read-only mount
  ovl: plumb through flush method
parents d42f323a 5e717c6f

Documentation/filesystems/overlayfs.rst

+12 −14
Original line number Diff line number Diff line
@@ -40,17 +40,17 @@ On 64bit systems, even if all overlay layers are not on the same 
underlying filesystem, the same compliant behavior could be achieved

with the "xino" feature.  The "xino" feature composes a unique object

identifier from the real object st_ino and an underlying fsid index.



If all underlying filesystems support NFS file handles and export file

handles with 32bit inode number encoding (e.g. ext4), overlay filesystem

will use the high inode number bits for fsid.  Even when the underlying

filesystem uses 64bit inode numbers, users can still enable the "xino"

feature with the "-o xino=on" overlay mount option.  That is useful for the

case of underlying filesystems like xfs and tmpfs, which use 64bit inode

numbers, but are very unlikely to use the high inode number bits.  In case

The "xino" feature uses the high inode number bits for fsid, because the

underlying filesystems rarely use the high inode number bits.  In case

the underlying inode number does overflow into the high xino bits, overlay

filesystem will fall back to the non xino behavior for that inode.



The "xino" feature can be enabled with the "-o xino=on" overlay mount option.

If all underlying filesystems support NFS file handles, the value of st_ino

for overlay filesystem objects is not only unique, but also persistent over

the lifetime of the filesystem.  The "-o xino=auto" overlay mount option

enables the "xino" feature only if the persistent st_ino requirement is met.



The following table summarizes what can be expected in different overlay

configurations.
@@ -66,14 +66,13 @@ Inode properties 
| All layers   |  Y  |  Y   |  Y  |  Y   |  Y     |   Y    |  Y     |  Y    |

| on same fs   |     |      |     |      |        |        |        |       |

+--------------+-----+------+-----+------+--------+--------+--------+-------+

| Layers not   |  N  |  Y   |  Y  |  N   |  N     |   Y    |  N     |  Y    |

| Layers not   |  N  |  N   |  Y  |  N   |  N     |   Y    |  N     |  Y    |

| on same fs,  |     |      |     |      |        |        |        |       |

| xino=off     |     |      |     |      |        |        |        |       |

+--------------+-----+------+-----+------+--------+--------+--------+-------+

| xino=on/auto |  Y  |  Y   |  Y  |  Y   |  Y     |   Y    |  Y     |  Y    |

|              |     |      |     |      |        |        |        |       |

+--------------+-----+------+-----+------+--------+--------+--------+-------+

| xino=on/auto,|  N  |  Y   |  Y  |  N   |  N     |   Y    |  N     |  Y    |

| xino=on/auto,|  N  |  N   |  Y  |  N   |  N     |   Y    |  N     |  Y    |

| ino overflow |     |      |     |      |        |        |        |       |

+--------------+-----+------+-----+------+--------+--------+--------+-------+
@@ -81,7 +80,6 @@ Inode properties 
/proc files, such as /proc/locks and /proc/self/fdinfo/<fd> of an inotify

file descriptor.





Upper and Lower

---------------
@@ -461,7 +459,7 @@ enough free bits in the inode number, then overlayfs will not be able to 
guarantee that the values of st_ino and st_dev returned by stat(2) and the

value of d_ino returned by readdir(3) will act like on a normal filesystem.

E.g. the value of st_dev may be different for two objects in the same

overlay filesystem and the value of st_ino for directory objects may not be

overlay filesystem and the value of st_ino for filesystem objects may not be

persistent and could change even while the overlay filesystem is mounted, as

summarized in the `Inode properties`_ table above.
@@ -476,7 +474,7 @@ a crash or deadlock. 


Offline changes, when the overlay is not mounted, are allowed to the

upper tree.  Offline changes to the lower tree are only allowed if the

"metadata only copy up", "inode index", and "redirect_dir" features

"metadata only copy up", "inode index", "xino" and "redirect_dir" features

have not been used.  If the lower tree is modified and any of these

features has been used, the behavior of the overlay is undefined,

though it will not result in a crash or deadlock.

fs/overlayfs/copy_up.c

+2 −1
Original line number Diff line number Diff line
@@ -932,7 +932,7 @@ static int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry, 
static int ovl_copy_up_flags(struct dentry *dentry, int flags)

{

	int err = 0;

	const struct cred *old_cred = ovl_override_creds(dentry->d_sb);

	const struct cred *old_cred;

	bool disconnected = (dentry->d_flags & DCACHE_DISCONNECTED);



	/*
@@ -943,6 +943,7 @@ static int ovl_copy_up_flags(struct dentry *dentry, int flags) 
	if (WARN_ON(disconnected && d_is_dir(dentry)))

		return -EIO;



	old_cred = ovl_override_creds(dentry->d_sb);

	while (!err) {

		struct dentry *next;

		struct dentry *parent = NULL;

fs/overlayfs/file.c

+21 −0
Original line number Diff line number Diff line
@@ -571,6 +571,26 @@ static loff_t ovl_remap_file_range(struct file *file_in, loff_t pos_in, 
			    remap_flags, op);

}



static int ovl_flush(struct file *file, fl_owner_t id)

{

	struct fd real;

	const struct cred *old_cred;

	int err;



	err = ovl_real_fdget(file, &real);

	if (err)

		return err;



	if (real.file->f_op->flush) {

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

		err = real.file->f_op->flush(real.file, id);

		revert_creds(old_cred);

	}

	fdput(real);



	return err;

}



const struct file_operations ovl_file_operations = {

	.open		= ovl_open,

	.release	= ovl_release,
@@ -581,6 +601,7 @@ const struct file_operations ovl_file_operations = { 
	.mmap		= ovl_mmap,

	.fallocate	= ovl_fallocate,

	.fadvise	= ovl_fadvise,

	.flush		= ovl_flush,

	.splice_read    = generic_file_splice_read,

	.splice_write   = iter_file_splice_write,

fs/overlayfs/inode.c

+7 −11
Original line number Diff line number Diff line
@@ -97,7 +97,7 @@ int ovl_setattr(struct user_namespace *mnt_userns, struct dentry *dentry, 
	return err;

}



static int ovl_map_dev_ino(struct dentry *dentry, struct kstat *stat, int fsid)

static void ovl_map_dev_ino(struct dentry *dentry, struct kstat *stat, int fsid)

{

	bool samefs = ovl_same_fs(dentry->d_sb);

	unsigned int xinobits = ovl_xino_bits(dentry->d_sb);
@@ -110,21 +110,21 @@ static int ovl_map_dev_ino(struct dentry *dentry, struct kstat *stat, int fsid) 
		 * which is friendly to du -x.

		 */

		stat->dev = dentry->d_sb->s_dev;

		return 0;

		return;

	} else if (xinobits) {

		/*

		 * All inode numbers of underlying fs should not be using the

		 * high xinobits, so we use high xinobits to partition the

		 * overlay st_ino address space. The high bits holds the fsid

		 * (upper fsid is 0). The lowest xinobit is reserved for mapping

		 * the non-peresistent inode numbers range in case of overflow.

		 * the non-persistent inode numbers range in case of overflow.

		 * This way all overlay inode numbers are unique and use the

		 * overlay st_dev.

		 */

		if (likely(!(stat->ino >> xinoshift))) {

			stat->ino |= ((u64)fsid) << (xinoshift + 1);

			stat->dev = dentry->d_sb->s_dev;

			return 0;

			return;

		} else if (ovl_xino_warn(dentry->d_sb)) {

			pr_warn_ratelimited("inode number too big (%pd2, ino=%llu, xinobits=%d)\n",

					    dentry, stat->ino, xinobits);
@@ -153,8 +153,6 @@ static int ovl_map_dev_ino(struct dentry *dentry, struct kstat *stat, int fsid) 
		 */

		stat->dev = OVL_FS(dentry->d_sb)->fs[fsid].pseudo_dev;

	}



	return 0;

}



int ovl_getattr(struct user_namespace *mnt_userns, const struct path *path,
@@ -253,9 +251,7 @@ int ovl_getattr(struct user_namespace *mnt_userns, const struct path *path, 
		}

	}



	err = ovl_map_dev_ino(dentry, stat, fsid);

	if (err)

		goto out;

	ovl_map_dev_ino(dentry, stat, fsid);



	/*

	 * It's probably not worth it to count subdirs to get the
@@ -410,7 +406,7 @@ static bool ovl_can_list(struct super_block *sb, const char *s) 
	if (ovl_is_private_xattr(sb, s))

		return false;



	/* List all non-trusted xatts */

	/* List all non-trusted xattrs */

	if (strncmp(s, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN) != 0)

		return true;
@@ -615,7 +611,7 @@ static const struct address_space_operations ovl_aops = { 
 * stackable i_mutex locks according to stack level of the super

 * block instance. An overlayfs instance can never be in stack

 * depth 0 (there is always a real fs below it).  An overlayfs

 * inode lock will use the lockdep annotaion ovl_i_mutex_key[depth].

 * inode lock will use the lockdep annotation ovl_i_mutex_key[depth].

 *

 * For example, here is a snip from /proc/lockdep_chains after

 * dir_iterate of nested overlayfs:

fs/overlayfs/namei.c

+1 −0
Original line number Diff line number Diff line
@@ -919,6 +919,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, 
			continue;



		if ((uppermetacopy || d.metacopy) && !ofs->config.metacopy) {

			dput(this);

			err = -EPERM;

			pr_warn_ratelimited("refusing to follow metacopy origin for (%pd2)\n", dentry);

			goto out_put;