Commit 06170154 authored by Amir Goldstein's avatar Amir Goldstein Committed by Miklos Szeredi
Browse files

ovl: lookup indexed ancestor of lower dir 



ovl_lookup_real() in lower layer walks back lower parents to find the
topmost indexed parent. If an indexed ancestor is found before reaching
lower layer root, ovl_lookup_real() is called recursively with upper
layer to walk back from indexed upper to the topmost connected/hashed
upper parent (or up to root).

ovl_lookup_real() in upper layer then walks forward to connect the topmost
upper overlay dir dentry and ovl_lookup_real() in lower layer continues to
walk forward to connect the decoded lower overlay dir dentry.

Signed-off-by: default avatarAmir Goldstein <amir73il@gmail.com>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
parent 4b91c30a

fs/overlayfs/export.c

+40 −1
Original line number Diff line number Diff line
@@ -294,6 +294,10 @@ fail: 
	goto out;

}



static struct dentry *ovl_lookup_real(struct super_block *sb,

				      struct dentry *real,

				      struct ovl_layer *layer);



/*

 * Lookup an indexed or hashed overlay dentry by real inode.

 */
@@ -301,9 +305,16 @@ static struct dentry *ovl_lookup_real_inode(struct super_block *sb, 
					    struct dentry *real,

					    struct ovl_layer *layer)

{

	struct ovl_fs *ofs = sb->s_fs_info;

	struct ovl_layer upper_layer = { .mnt = ofs->upper_mnt };

	struct dentry *index = NULL;

	struct dentry *this = NULL;

	struct inode *inode;



	/*

	 * Decoding upper dir from index is expensive, so first try to lookup

	 * overlay dentry in inode/dcache.

	 */

	inode = ovl_lookup_inode(sb, real, !layer->idx);

	if (IS_ERR(inode))

		return ERR_CAST(inode);
@@ -312,7 +323,35 @@ static struct dentry *ovl_lookup_real_inode(struct super_block *sb, 
		iput(inode);

	}



	/* TODO: use index when looking up by origin inode */

	/*

	 * For decoded lower dir file handle, lookup index by origin to check

	 * if lower dir was copied up and and/or removed.

	 */

	if (!this && layer->idx && ofs->indexdir && !WARN_ON(!d_is_dir(real))) {

		index = ovl_lookup_index(ofs, NULL, real, false);

		if (IS_ERR(index))

			return index;

	}



	/* Get connected upper overlay dir from index */

	if (index) {

		struct dentry *upper = ovl_index_upper(ofs, index);



		dput(index);

		if (IS_ERR_OR_NULL(upper))

			return upper;



		/*

		 * ovl_lookup_real() in lower layer may call recursively once to

		 * ovl_lookup_real() in upper layer. The first level call walks

		 * back lower parents to the topmost indexed parent. The second

		 * recursive call walks back from indexed upper to the topmost

		 * connected/hashed upper parent (or up to root).

		 */

		this = ovl_lookup_real(sb, upper, &upper_layer);

		dput(upper);

	}



	if (!this)

		return NULL;

fs/overlayfs/namei.c

+14 −6
Original line number Diff line number Diff line
@@ -661,11 +661,9 @@ struct dentry *ovl_get_index_fh(struct ovl_fs *ofs, struct ovl_fh *fh) 
	return ERR_PTR(err);

}



static struct dentry *ovl_lookup_index(struct dentry *dentry,

				       struct dentry *upper,

				       struct dentry *origin)

struct dentry *ovl_lookup_index(struct ovl_fs *ofs, struct dentry *upper,

				struct dentry *origin, bool verify)

{

	struct ovl_fs *ofs = dentry->d_sb->s_fs_info;

	struct dentry *index;

	struct inode *inode;

	struct qstr name;
@@ -693,6 +691,16 @@ static struct dentry *ovl_lookup_index(struct dentry *dentry, 
	inode = d_inode(index);

	if (d_is_negative(index)) {

		goto out_dput;

	} else if (ovl_is_whiteout(index) && !verify) {

		/*

		 * When index lookup is called with !verify for decoding an

		 * overlay file handle, a whiteout index implies that decode

		 * should treat file handle as stale and no need to print a

		 * warning about it.

		 */

		dput(index);

		index = ERR_PTR(-ESTALE);

		goto out;

	} else if (ovl_dentry_weird(index) || ovl_is_whiteout(index) ||

		   ((inode->i_mode ^ d_inode(origin)->i_mode) & S_IFMT)) {

		/*
@@ -706,7 +714,7 @@ static struct dentry *ovl_lookup_index(struct dentry *dentry, 
				    index, d_inode(index)->i_mode & S_IFMT,

				    d_inode(origin)->i_mode & S_IFMT);

		goto fail;

	} else if (is_dir) {

	} else if (is_dir && verify) {

		if (!upper) {

			pr_warn_ratelimited("overlayfs: suspected uncovered redirected dir found (origin=%pd2, index=%pd2).\n",

					    origin, index);
@@ -943,7 +951,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, 


	if (origin && ovl_indexdir(dentry->d_sb) &&

	    (!d.is_dir || ovl_index_all(dentry->d_sb))) {

		index = ovl_lookup_index(dentry, upperdentry, origin);

		index = ovl_lookup_index(ofs, upperdentry, origin, true);

		if (IS_ERR(index)) {

			err = PTR_ERR(index);

			index = NULL;

fs/overlayfs/overlayfs.h

+2 −0
Original line number Diff line number Diff line
@@ -274,6 +274,8 @@ struct dentry *ovl_index_upper(struct ovl_fs *ofs, struct dentry *index); 
int ovl_verify_index(struct ovl_fs *ofs, struct dentry *index);

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

struct dentry *ovl_get_index_fh(struct ovl_fs *ofs, struct ovl_fh *fh);

struct dentry *ovl_lookup_index(struct ovl_fs *ofs, struct dentry *upper,

				struct dentry *origin, bool verify);

int ovl_path_next(int idx, struct dentry *dentry, struct path *path);

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

			  unsigned int flags);

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