ovl: lookup connected ancestor of dir in inode cache (4b91c30a) · Commits · 戴 / test

fs/overlayfs/export.c

+93 −6

Original line number	Diff line number	Diff line
		@@ -294,6 +294,88 @@ fail:
		goto out;
		}

		/*
		* Lookup an indexed or hashed overlay dentry by real inode.
		*/
		static struct dentry ovl_lookup_real_inode(struct super_block sb,
		struct dentry *real,
		struct ovl_layer *layer)
		{
		struct dentry *this = NULL;
		struct inode *inode;

		inode = ovl_lookup_inode(sb, real, !layer->idx);
		if (IS_ERR(inode))
		return ERR_CAST(inode);
		if (inode) {
		this = d_find_any_alias(inode);
		iput(inode);
		}

		/* TODO: use index when looking up by origin inode */
		if (!this)
		return NULL;

		if (WARN_ON(ovl_dentry_real_at(this, layer->idx) != real)) {
		dput(this);
		this = ERR_PTR(-EIO);
		}

		return this;
		}

		/*
		* Lookup an indexed or hashed overlay dentry, whose real dentry is an
		* ancestor of @real.
		*/
		static struct dentry ovl_lookup_real_ancestor(struct super_block sb,
		struct dentry *real,
		struct ovl_layer *layer)
		{
		struct dentry next, parent = NULL;
		struct dentry *ancestor = ERR_PTR(-EIO);

		if (real == layer->mnt->mnt_root)
		return dget(sb->s_root);

		/* Find the topmost indexed or hashed ancestor */
		next = dget(real);
		for (;;) {
		parent = dget_parent(next);

		/*
		* Lookup a matching overlay dentry in inode/dentry
		* cache or in index by real inode.
		*/
		ancestor = ovl_lookup_real_inode(sb, next, layer);
		if (ancestor)
		break;

		if (parent == layer->mnt->mnt_root) {
		ancestor = dget(sb->s_root);
		break;
		}

		/*
		* If @real has been moved out of the layer root directory,
		* we will eventully hit the real fs root. This cannot happen
		* by legit overlay rename, so we return error in that case.
		*/
		if (parent == next) {
		ancestor = ERR_PTR(-EXDEV);
		break;
		}

		dput(next);
		next = parent;
		}

		dput(parent);
		dput(next);

		return ancestor;
		}

		/*
		* Lookup a connected overlay dentry whose real dentry is @real.
		* If @real is on upper layer, we lookup a child overlay dentry with the same
		@@ -306,9 +388,10 @@ static struct dentry ovl_lookup_real(struct super_block sb,
		struct dentry *connected;
		int err = 0;

		/* TODO: use index when looking up by lower real dentry */
		connected = ovl_lookup_real_ancestor(sb, real, layer);
		if (IS_ERR(connected))
		return connected;

		connected = dget(sb->s_root);
		while (!err) {
		struct dentry next, this;
		struct dentry *parent = NULL;
		@@ -365,11 +448,15 @@ static struct dentry ovl_lookup_real(struct super_block sb,
		* overlay rename of child away from 'connected' parent.
		* In this case, we need to restart the lookup from the
		* top, because we cannot trust that 'real_connected' is
		* still an ancestor of 'real'.
		* still an ancestor of 'real'. There is a good chance
		* that the renamed overlay ancestor is now in cache, so
		* ovl_lookup_real_ancestor() will find it and we can
		* continue to connect exactly from where lookup failed.
		*/
		if (err == -ECHILD) {
		this = dget(sb->s_root);
		err = 0;
		this = ovl_lookup_real_ancestor(sb, real,
		layer);
		err = IS_ERR(this) ? PTR_ERR(this) : 0;
		}
		if (!err) {
		dput(connected);
		@@ -494,7 +581,7 @@ static struct dentry ovl_lower_fh_to_d(struct super_block sb,
		} else if (is_deleted) {
		/* Lookup deleted non-dir by origin inode */
		if (!d_is_dir(origin.dentry))
		inode = ovl_lookup_inode(sb, origin.dentry);
		inode = ovl_lookup_inode(sb, origin.dentry, false);
		err = -ESTALE;
		if (!inode \|\| atomic_read(&inode->i_count) == 1)
		goto out_err;

fs/overlayfs/inode.c

+15 −6

Original line number	Diff line number	Diff line
		@@ -614,9 +614,15 @@ static int ovl_inode_set(struct inode inode, void data)
		}

		static bool ovl_verify_inode(struct inode inode, struct dentry lowerdentry,
		struct dentry *upperdentry)
		struct dentry *upperdentry, bool strict)
		{
		if (S_ISDIR(inode->i_mode)) {
		/*
		* For directories, @strict verify from lookup path performs consistency
		* checks, so NULL lower/upper in dentry must match NULL lower/upper in
		* inode. Non @strict verify from NFS handle decode path passes NULL for
		* 'unknown' lower/upper.
		*/
		if (S_ISDIR(inode->i_mode) && strict) {
		/* Real lower dir moved to upper layer under us? */
		if (!lowerdentry && ovl_inode_lower(inode))
		return false;
		@@ -645,15 +651,17 @@ static bool ovl_verify_inode(struct inode inode, struct dentry lowerdentry,
		return true;
		}

		struct inode ovl_lookup_inode(struct super_block sb, struct dentry *origin)
		struct inode ovl_lookup_inode(struct super_block sb, struct dentry *real,
		bool is_upper)
		{
		struct inode inode, key = d_inode(origin);
		struct inode inode, key = d_inode(real);

		inode = ilookup5(sb, (unsigned long) key, ovl_inode_test, key);
		if (!inode)
		return NULL;

		if (!ovl_verify_inode(inode, origin, NULL)) {
		if (!ovl_verify_inode(inode, is_upper ? NULL : real,
		is_upper ? real : NULL, false)) {
		iput(inode);
		return ERR_PTR(-ESTALE);
		}
		@@ -704,7 +712,8 @@ struct inode ovl_get_inode(struct super_block sb, struct dentry *upperdentry,
		* Verify that the underlying files stored in the inode
		* match those in the dentry.
		*/
		if (!ovl_verify_inode(inode, lowerdentry, upperdentry)) {
		if (!ovl_verify_inode(inode, lowerdentry, upperdentry,
		true)) {
		iput(inode);
		inode = ERR_PTR(-ESTALE);
		goto out;

fs/overlayfs/overlayfs.h

+2 −1

Original line number	Diff line number	Diff line
		@@ -323,7 +323,8 @@ int ovl_update_time(struct inode inode, struct timespec ts, int flags);
		bool ovl_is_private_xattr(const char *name);

		struct inode ovl_new_inode(struct super_block sb, umode_t mode, dev_t rdev);
		struct inode ovl_lookup_inode(struct super_block sb, struct dentry *origin);
		struct inode ovl_lookup_inode(struct super_block sb, struct dentry *real,
		bool is_upper);
		struct inode ovl_get_inode(struct super_block sb, struct dentry *upperdentry,
		struct dentry lowerdentry, struct dentry index,
		unsigned int numlower);

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