Commit b9343632 authored by Chandan Rajendra's avatar Chandan Rajendra Committed by Miklos Szeredi
Browse files

ovl: re-structure overlay lower layers in-memory 



Define new structures to represent overlay instance lower layers and
overlay merge dir lower layers to make room for storing more per layer
information in-memory.

Instead of keeping the fs instance lower layers in an array of struct
vfsmount, keep them in an array of new struct ovl_layer, that has a
pointer to struct vfsmount.

Instead of keeping the dentry lower layers in an array of struct path,
keep them in an array of new struct ovl_path, that has a pointer to
struct dentry and to struct ovl_layer.

Add a small helper to find the fs layer id that correspopnds to a lower
struct ovl_path and use it in ovl_lookup().

[amir: split re-structure from anonymous bdev patch]

Signed-off-by: default avatarChandan Rajendra <chandan@linux.vnet.ibm.com>
Signed-off-by: default avatarAmir Goldstein <amir73il@gmail.com>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
parent ee023c30

fs/overlayfs/namei.c

+31 −21
Original line number Diff line number Diff line
@@ -285,16 +285,15 @@ static int ovl_lookup_layer(struct dentry *base, struct ovl_lookup_data *d, 




static int ovl_check_origin(struct dentry *upperdentry,

			    struct path *lowerstack, unsigned int numlower,

			    struct path **stackp, unsigned int *ctrp)

			    struct ovl_path *lower, unsigned int numlower,

			    struct ovl_path **stackp, unsigned int *ctrp)

{

	struct vfsmount *mnt;

	struct dentry *origin = NULL;

	int i;





	for (i = 0; i < numlower; i++) {

		mnt = lowerstack[i].mnt;

		mnt = lower[i].layer->mnt;

		origin = ovl_get_origin(upperdentry, mnt);

		if (IS_ERR(origin))

			return PTR_ERR(origin);
@@ -308,12 +307,12 @@ static int ovl_check_origin(struct dentry *upperdentry, 


	BUG_ON(*ctrp);

	if (!*stackp)

		*stackp = kmalloc(sizeof(struct path), GFP_KERNEL);

		*stackp = kmalloc(sizeof(struct ovl_path), GFP_KERNEL);

	if (!*stackp) {

		dput(origin);

		return -ENOMEM;

	}

	**stackp = (struct path) { .dentry = origin, .mnt = mnt };

	**stackp = (struct ovl_path){.dentry = origin, .layer = lower[i].layer};

	*ctrp = 1;



	return 0;
@@ -383,13 +382,13 @@ fail: 
 * OVL_XATTR_ORIGIN and that origin file handle can be decoded to lower path.

 * Return 0 on match, -ESTALE on mismatch or stale origin, < 0 on error.

 */

int ovl_verify_index(struct dentry *index, struct path *lowerstack,

int ovl_verify_index(struct dentry *index, struct ovl_path *lower,

		     unsigned int numlower)

{

	struct ovl_fh *fh = NULL;

	size_t len;

	struct path origin = { };

	struct path *stack = &origin;

	struct ovl_path origin = { };

	struct ovl_path *stack = &origin;

	unsigned int ctr = 0;

	int err;
@@ -428,7 +427,7 @@ int ovl_verify_index(struct dentry *index, struct path *lowerstack, 
	if (err)

		goto fail;



	err = ovl_check_origin(index, lowerstack, numlower, &stack, &ctr);

	err = ovl_check_origin(index, lower, numlower, &stack, &ctr);

	if (!err && !ctr)

		err = -ESTALE;

	if (err)
@@ -567,11 +566,24 @@ int ovl_path_next(int idx, struct dentry *dentry, struct path *path) 
		idx++;

	}

	BUG_ON(idx > oe->numlower);

	*path = oe->lowerstack[idx - 1];

	path->dentry = oe->lowerstack[idx - 1].dentry;

	path->mnt = oe->lowerstack[idx - 1].layer->mnt;



	return (idx < oe->numlower) ? idx + 1 : -1;

}



static int ovl_find_layer(struct ovl_fs *ofs, struct ovl_path *path)

{

	int i;



	for (i = 0; i < ofs->numlower; i++) {

		if (ofs->lower_layers[i].mnt == path->layer->mnt)

			break;

	}



	return i;

}



struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,

			  unsigned int flags)

{
@@ -580,7 +592,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, 
	struct ovl_fs *ofs = dentry->d_sb->s_fs_info;

	struct ovl_entry *poe = dentry->d_parent->d_fsdata;

	struct ovl_entry *roe = dentry->d_sb->s_root->d_fsdata;

	struct path *stack = NULL;

	struct ovl_path *stack = NULL;

	struct dentry *upperdir, *upperdentry = NULL;

	struct dentry *index = NULL;

	unsigned int ctr = 0;
@@ -645,17 +657,17 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, 


	if (!d.stop && poe->numlower) {

		err = -ENOMEM;

		stack = kcalloc(ofs->numlower, sizeof(struct path),

		stack = kcalloc(ofs->numlower, sizeof(struct ovl_path),

				GFP_KERNEL);

		if (!stack)

			goto out_put_upper;

	}



	for (i = 0; !d.stop && i < poe->numlower; i++) {

		struct path lowerpath = poe->lowerstack[i];

		struct ovl_path lower = poe->lowerstack[i];



		d.last = i == poe->numlower - 1;

		err = ovl_lookup_layer(lowerpath.dentry, &d, &this);

		err = ovl_lookup_layer(lower.dentry, &d, &this);

		if (err)

			goto out_put;
@@ -663,7 +675,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, 
			continue;



		stack[ctr].dentry = this;

		stack[ctr].mnt = lowerpath.mnt;

		stack[ctr].layer = lower.layer;

		ctr++;



		if (d.stop)
@@ -673,10 +685,8 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, 
			poe = roe;



			/* Find the current layer on the root dentry */

			for (i = 0; i < poe->numlower; i++)

				if (poe->lowerstack[i].mnt == lowerpath.mnt)

					break;

			if (WARN_ON(i == poe->numlower))

			i = ovl_find_layer(ofs, &lower);

			if (WARN_ON(i == ofs->numlower))

				break;

		}

	}
@@ -699,7 +709,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, 
		goto out_put;



	oe->opaque = upperopaque;

	memcpy(oe->lowerstack, stack, sizeof(struct path) * ctr);

	memcpy(oe->lowerstack, stack, sizeof(struct ovl_path) * ctr);

	dentry->d_fsdata = oe;



	if (upperdentry)

fs/overlayfs/overlayfs.h

+2 −2
Original line number Diff line number Diff line
@@ -251,7 +251,7 @@ static inline bool ovl_is_impuredir(struct dentry *dentry) 
/* namei.c */

int ovl_verify_origin(struct dentry *dentry, struct vfsmount *mnt,

		      struct dentry *origin, bool is_upper, bool set);

int ovl_verify_index(struct dentry *index, struct path *lowerstack,

int ovl_verify_index(struct dentry *index, struct ovl_path *lower,

		     unsigned int numlower);

int ovl_get_index_name(struct dentry *origin, struct qstr *name);

int ovl_path_next(int idx, struct dentry *dentry, struct path *path);
@@ -268,7 +268,7 @@ int ovl_check_d_type_supported(struct path *realpath); 
void ovl_workdir_cleanup(struct inode *dir, struct vfsmount *mnt,

			 struct dentry *dentry, int level);

int ovl_indexdir_cleanup(struct dentry *dentry, struct vfsmount *mnt,

			 struct path *lowerstack, unsigned int numlower);

			 struct ovl_path *lower, unsigned int numlower);



/* inode.c */

int ovl_set_nlink_upper(struct dentry *dentry);

fs/overlayfs/ovl_entry.h

+11 −2
Original line number Diff line number Diff line
@@ -17,11 +17,20 @@ struct ovl_config { 
	bool index;

};



struct ovl_layer {

	struct vfsmount *mnt;

};



struct ovl_path {

	struct ovl_layer *layer;

	struct dentry *dentry;

};



/* private information held for overlayfs's superblock */

struct ovl_fs {

	struct vfsmount *upper_mnt;

	unsigned numlower;

	struct vfsmount **lower_mnt;

	struct ovl_layer *lower_layers;

	/* workbasedir is the path at workdir= mount option */

	struct dentry *workbasedir;

	/* workdir is the 'work' directory under workbasedir */
@@ -52,7 +61,7 @@ struct ovl_entry { 
		struct rcu_head rcu;

	};

	unsigned numlower;

	struct path lowerstack[];

	struct ovl_path lowerstack[];

};



struct ovl_entry *ovl_alloc_entry(unsigned int numlower);

fs/overlayfs/readdir.c

+2 −2
Original line number Diff line number Diff line
@@ -1014,7 +1014,7 @@ void ovl_workdir_cleanup(struct inode *dir, struct vfsmount *mnt, 
}



int ovl_indexdir_cleanup(struct dentry *dentry, struct vfsmount *mnt,

			 struct path *lowerstack, unsigned int numlower)

			 struct ovl_path *lower, unsigned int numlower)

{

	int err;

	struct dentry *index = NULL;
@@ -1049,7 +1049,7 @@ int ovl_indexdir_cleanup(struct dentry *dentry, struct vfsmount *mnt, 
			index = NULL;

			break;

		}

		err = ovl_verify_index(index, lowerstack, numlower);

		err = ovl_verify_index(index, lower, numlower);

		/* Cleanup stale and orphan index entries */

		if (err && (err == -ESTALE || err == -ENOENT))

			err = ovl_cleanup(dir, index);

fs/overlayfs/super.c

+34 −28
Original line number Diff line number Diff line
@@ -220,8 +220,8 @@ static void ovl_put_super(struct super_block *sb) 
		ovl_inuse_unlock(ufs->upper_mnt->mnt_root);

	mntput(ufs->upper_mnt);

	for (i = 0; i < ufs->numlower; i++)

		mntput(ufs->lower_mnt[i]);

	kfree(ufs->lower_mnt);

		mntput(ufs->lower_layers[i].mnt);

	kfree(ufs->lower_layers);



	kfree(ufs->config.lowerdir);

	kfree(ufs->config.upperdir);
@@ -1026,24 +1026,26 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) 
	}



	err = -ENOMEM;

	ufs->lower_mnt = kcalloc(numlower, sizeof(struct vfsmount *), GFP_KERNEL);

	if (ufs->lower_mnt == NULL)

	ufs->lower_layers = kcalloc(numlower, sizeof(struct ovl_layer),

				    GFP_KERNEL);

	if (ufs->lower_layers == NULL)

		goto out_put_workdir;

	for (i = 0; i < numlower; i++) {

		struct vfsmount *mnt = clone_private_mount(&stack[i]);

		struct vfsmount *mnt;



		mnt = clone_private_mount(&stack[i]);

		err = PTR_ERR(mnt);

		if (IS_ERR(mnt)) {

			pr_err("overlayfs: failed to clone lowerpath\n");

			goto out_put_lower_mnt;

			goto out_put_lower_layers;

		}

		/*

		 * Make lower_mnt R/O.  That way fchmod/fchown on lower file

		 * Make lower layers R/O.  That way fchmod/fchown on lower file

		 * will fail instead of modifying lower fs.

		 */

		mnt->mnt_flags |= MNT_READONLY | MNT_NOATIME;



		ufs->lower_mnt[ufs->numlower] = mnt;

		ufs->lower_layers[ufs->numlower].mnt = mnt;

		ufs->numlower++;



		/* Check if all lower layers are on same sb */
@@ -1059,13 +1061,25 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) 
	else if (ufs->upper_mnt->mnt_sb != ufs->same_sb)

		ufs->same_sb = NULL;



	err = -ENOMEM;

	oe = ovl_alloc_entry(numlower);

	if (!oe)

		goto out_put_lower_layers;



	for (i = 0; i < numlower; i++) {

		oe->lowerstack[i].dentry = stack[i].dentry;

		oe->lowerstack[i].layer = &(ufs->lower_layers[i]);

	}



	if (!(ovl_force_readonly(ufs)) && ufs->config.index) {

		/* Verify lower root is upper root origin */

		err = ovl_verify_origin(upperpath.dentry, ufs->lower_mnt[0],

					stack[0].dentry, false, true);

		err = ovl_verify_origin(upperpath.dentry,

					oe->lowerstack[0].layer->mnt,

					oe->lowerstack[0].dentry,

					false, true);

		if (err) {

			pr_err("overlayfs: failed to verify upper root origin\n");

			goto out_put_lower_mnt;

			goto out_free_oe;

		}



		ufs->indexdir = ovl_workdir_create(sb, ufs, workpath.dentry,
@@ -1081,7 +1095,8 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) 
			if (!err)

				err = ovl_indexdir_cleanup(ufs->indexdir,

							   ufs->upper_mnt,

							   stack, numlower);

							   oe->lowerstack,

							   numlower);

		}

		if (err || !ufs->indexdir)

			pr_warn("overlayfs: try deleting index dir or mounting with '-o index=off' to disable inodes index.\n");
@@ -1106,11 +1121,6 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) 
	/* Never override disk quota limits or use reserved space */

	cap_lower(cred->cap_effective, CAP_SYS_RESOURCE);



	err = -ENOMEM;

	oe = ovl_alloc_entry(numlower);

	if (!oe)

		goto out_put_cred;



	sb->s_magic = OVERLAYFS_SUPER_MAGIC;

	sb->s_op = &ovl_super_operations;

	sb->s_xattr = ovl_xattr_handlers;
@@ -1119,11 +1129,12 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) 


	root_dentry = d_make_root(ovl_new_inode(sb, S_IFDIR, 0));

	if (!root_dentry)

		goto out_free_oe;

		goto out_put_cred;



	mntput(upperpath.mnt);

	for (i = 0; i < numlower; i++)

		mntput(stack[i].mnt);

	kfree(stack);

	mntput(workpath.mnt);

	kfree(lowertmp);
@@ -1132,11 +1143,6 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) 
		if (ovl_is_impuredir(upperpath.dentry))

			ovl_set_flag(OVL_IMPURE, d_inode(root_dentry));

	}

	for (i = 0; i < numlower; i++) {

		oe->lowerstack[i].dentry = stack[i].dentry;

		oe->lowerstack[i].mnt = ufs->lower_mnt[i];

	}

	kfree(stack);



	root_dentry->d_fsdata = oe;
@@ -1149,16 +1155,16 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) 


	return 0;



out_free_oe:

	kfree(oe);

out_put_cred:

	put_cred(ufs->creator_cred);

out_put_indexdir:

	dput(ufs->indexdir);

out_put_lower_mnt:

out_free_oe:

	kfree(oe);

out_put_lower_layers:

	for (i = 0; i < ufs->numlower; i++)

		mntput(ufs->lower_mnt[i]);

	kfree(ufs->lower_mnt);

		mntput(ufs->lower_layers[i].mnt);

	kfree(ufs->lower_layers);

out_put_workdir:

	dput(ufs->workdir);

	mntput(ufs->upper_mnt);

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