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Commit e7dd0e71 authored by Amir Goldstein's avatar Amir Goldstein Committed by Miklos Szeredi
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ovl: whiteout index when union nlink drops to zero 



With NFS export feature enabled, when overlay inode nlink drops to
zero, instead of removing the index entry, replace it with a whiteout
index entry.

This is needed for NFS export in order to prevent future open by handle
from opening the lower file directly.

Signed-off-by: default avatarAmir Goldstein <amir73il@gmail.com>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
parent 89a17556

fs/overlayfs/dir.c

+35 −23
Original line number Diff line number Diff line
@@ -63,8 +63,7 @@ struct dentry *ovl_lookup_temp(struct dentry *workdir) 
}



/* caller holds i_mutex on workdir */

static struct dentry *ovl_whiteout(struct dentry *workdir,

				   struct dentry *dentry)

static struct dentry *ovl_whiteout(struct dentry *workdir)

{

	int err;

	struct dentry *whiteout;
@@ -83,6 +82,38 @@ static struct dentry *ovl_whiteout(struct dentry *workdir, 
	return whiteout;

}



/* Caller must hold i_mutex on both workdir and dir */

int ovl_cleanup_and_whiteout(struct dentry *workdir, struct inode *dir,

			     struct dentry *dentry)

{

	struct inode *wdir = workdir->d_inode;

	struct dentry *whiteout;

	int err;

	int flags = 0;



	whiteout = ovl_whiteout(workdir);

	err = PTR_ERR(whiteout);

	if (IS_ERR(whiteout))

		return err;



	if (d_is_dir(dentry))

		flags = RENAME_EXCHANGE;



	err = ovl_do_rename(wdir, whiteout, dir, dentry, flags);

	if (err)

		goto kill_whiteout;

	if (flags)

		ovl_cleanup(wdir, dentry);



out:

	dput(whiteout);

	return err;



kill_whiteout:

	ovl_cleanup(wdir, whiteout);

	goto out;

}



int ovl_create_real(struct inode *dir, struct dentry *newdentry,

		    struct cattr *attr, struct dentry *hardlink, bool debug)

{
@@ -591,14 +622,10 @@ static int ovl_remove_and_whiteout(struct dentry *dentry, 
				   struct list_head *list)

{

	struct dentry *workdir = ovl_workdir(dentry);

	struct inode *wdir = workdir->d_inode;

	struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);

	struct inode *udir = upperdir->d_inode;

	struct dentry *whiteout;

	struct dentry *upper;

	struct dentry *opaquedir = NULL;

	int err;

	int flags = 0;



	if (WARN_ON(!workdir))

		return -EROFS;
@@ -627,24 +654,13 @@ static int ovl_remove_and_whiteout(struct dentry *dentry, 
		goto out_dput_upper;

	}



	whiteout = ovl_whiteout(workdir, dentry);

	err = PTR_ERR(whiteout);

	if (IS_ERR(whiteout))

		goto out_dput_upper;



	if (d_is_dir(upper))

		flags = RENAME_EXCHANGE;



	err = ovl_do_rename(wdir, whiteout, udir, upper, flags);

	err = ovl_cleanup_and_whiteout(workdir, d_inode(upperdir), upper);

	if (err)

		goto kill_whiteout;

	if (flags)

		ovl_cleanup(wdir, upper);

		goto out_d_drop;



	ovl_dentry_version_inc(dentry->d_parent, true);

out_d_drop:

	d_drop(dentry);

	dput(whiteout);

out_dput_upper:

	dput(upper);

out_unlock:
@@ -653,10 +669,6 @@ static int ovl_remove_and_whiteout(struct dentry *dentry, 
	dput(opaquedir);

out:

	return err;



kill_whiteout:

	ovl_cleanup(wdir, whiteout);

	goto out_d_drop;

}



static int ovl_remove_upper(struct dentry *dentry, bool is_dir,

fs/overlayfs/overlayfs.h

+2 −0
Original line number Diff line number Diff line
@@ -321,6 +321,8 @@ static inline void ovl_copyattr(struct inode *from, struct inode *to) 
/* dir.c */

extern const struct inode_operations ovl_dir_inode_operations;

struct dentry *ovl_lookup_temp(struct dentry *workdir);

int ovl_cleanup_and_whiteout(struct dentry *workdir, struct inode *dir,

			     struct dentry *dentry);

struct cattr {

	dev_t rdev;

	umode_t mode;

fs/overlayfs/util.c

+11 −6
Original line number Diff line number Diff line
@@ -487,7 +487,8 @@ bool ovl_need_index(struct dentry *dentry) 
/* Caller must hold OVL_I(inode)->lock */

static void ovl_cleanup_index(struct dentry *dentry)

{

	struct inode *dir = ovl_indexdir(dentry->d_sb)->d_inode;

	struct dentry *indexdir = ovl_indexdir(dentry->d_sb);

	struct inode *dir = indexdir->d_inode;

	struct dentry *lowerdentry = ovl_dentry_lower(dentry);

	struct dentry *upperdentry = ovl_dentry_upper(dentry);

	struct dentry *index = NULL;
@@ -518,13 +519,17 @@ static void ovl_cleanup_index(struct dentry *dentry) 
	}



	inode_lock_nested(dir, I_MUTEX_PARENT);

	/* TODO: whiteout instead of cleanup to block future open by handle */

	index = lookup_one_len(name.name, ovl_indexdir(dentry->d_sb), name.len);

	index = lookup_one_len(name.name, indexdir, name.len);

	err = PTR_ERR(index);

	if (!IS_ERR(index))

		err = ovl_cleanup(dir, index);

	else

	if (IS_ERR(index)) {

		index = NULL;

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

		/* Whiteout orphan index to block future open by handle */

		err = ovl_cleanup_and_whiteout(indexdir, dir, index);

	} else {

		/* Cleanup orphan index entries */

		err = ovl_cleanup(dir, index);

	}



	inode_unlock(dir);

	if (err)