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Commit e28edc46 authored by Miklos Szeredi's avatar Miklos Szeredi
Browse files

ovl: consolidate lookup for underlying layers 



Use a common helper for lookup of upper and lower layers.  This paves the
way for looking up directory redirects.

No functional change.

Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
parent 48fab5d7

fs/overlayfs/namei.c

+86 −70
Original line number Diff line number Diff line
@@ -13,26 +13,13 @@ 
#include "overlayfs.h"

#include "ovl_entry.h"



static struct dentry *ovl_lookup_real(struct dentry *dir,

				      const struct qstr *name)

{

	struct dentry *dentry;



	dentry = lookup_one_len_unlocked(name->name, dir, name->len);

	if (IS_ERR(dentry)) {

		if (PTR_ERR(dentry) == -ENOENT ||

		    PTR_ERR(dentry) == -ENAMETOOLONG)

			dentry = NULL;

	} else if (!dentry->d_inode) {

		dput(dentry);

		dentry = NULL;

	} else if (ovl_dentry_weird(dentry)) {

		dput(dentry);

		/* Don't support traversing automounts and other weirdness */

		dentry = ERR_PTR(-EREMOTE);

	}

	return dentry;

}

struct ovl_lookup_data {

	struct qstr name;

	bool is_dir;

	bool opaque;

	bool stop;

	bool last;

};



static bool ovl_is_opaquedir(struct dentry *dentry)

{
@@ -49,6 +36,64 @@ static bool ovl_is_opaquedir(struct dentry *dentry) 
	return false;

}



static int ovl_lookup_single(struct dentry *base, struct ovl_lookup_data *d,

			     const char *name, unsigned int namelen,

			     struct dentry **ret)

{

	struct dentry *this;

	int err;



	this = lookup_one_len_unlocked(name, base, namelen);

	if (IS_ERR(this)) {

		err = PTR_ERR(this);

		this = NULL;

		if (err == -ENOENT || err == -ENAMETOOLONG)

			goto out;

		goto out_err;

	}

	if (!this->d_inode)

		goto put_and_out;



	if (ovl_dentry_weird(this)) {

		/* Don't support traversing automounts and other weirdness */

		err = -EREMOTE;

		goto out_err;

	}

	if (ovl_is_whiteout(this)) {

		d->stop = d->opaque = true;

		goto put_and_out;

	}

	if (!d_can_lookup(this)) {

		d->stop = true;

		if (d->is_dir)

			goto put_and_out;

		goto out;

	}

	d->is_dir = true;

	if (!d->last && ovl_is_opaquedir(this)) {

		d->stop = d->opaque = true;

		goto out;

	}

out:

	*ret = this;

	return 0;



put_and_out:

	dput(this);

	this = NULL;

	goto out;



out_err:

	dput(this);

	return err;

}



static int ovl_lookup_layer(struct dentry *base, struct ovl_lookup_data *d,

			    struct dentry **ret)

{

	return ovl_lookup_single(base, d, d->name.name, d->name.len, ret);

}



/*

 * Returns next layer in stack starting from top.

 * Returns -1 if this is the last layer.
@@ -82,11 +127,16 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, 
	unsigned int ctr = 0;

	struct inode *inode = NULL;

	bool upperopaque = false;

	bool stop = false;

	bool isdir = false;

	struct dentry *this;

	unsigned int i;

	int err;

	struct ovl_lookup_data d = {

		.name = dentry->d_name,

		.is_dir = false,

		.opaque = false,

		.stop = false,

		.last = !poe->numlower,

	};



	if (dentry->d_name.len > ofs->namelen)

		return ERR_PTR(-ENAMETOOLONG);
@@ -94,70 +144,36 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, 
	old_cred = ovl_override_creds(dentry->d_sb);

	upperdir = ovl_upperdentry_dereference(poe);

	if (upperdir) {

		this = ovl_lookup_real(upperdir, &dentry->d_name);

		err = PTR_ERR(this);

		if (IS_ERR(this))

		err = ovl_lookup_layer(upperdir, &d, &upperdentry);

		if (err)

			goto out;



		if (this) {

			if (unlikely(ovl_dentry_remote(this))) {

				dput(this);

		if (upperdentry && unlikely(ovl_dentry_remote(upperdentry))) {

			dput(upperdentry);

			err = -EREMOTE;

			goto out;

		}

			if (ovl_is_whiteout(this)) {

				dput(this);

				this = NULL;

				stop = upperopaque = true;

			} else if (!d_is_dir(this)) {

				stop = true;

			} else {

				isdir = true;

				if (poe->numlower && ovl_is_opaquedir(this))

					stop = upperopaque = true;

			}

		}

		upperdentry = this;

		upperopaque = d.opaque;

	}



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

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

		err = -ENOMEM;

		stack = kcalloc(poe->numlower, sizeof(struct path), GFP_KERNEL);

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

				GFP_TEMPORARY);

		if (!stack)

			goto out_put_upper;

	}



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

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

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



		this = ovl_lookup_real(lowerpath.dentry, &dentry->d_name);

		err = PTR_ERR(this);

		if (IS_ERR(this))

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

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

		if (err)

			goto out_put;



		if (!this)

			continue;

		if (ovl_is_whiteout(this)) {

			dput(this);

			break;

		}

		/*

		 * If this is a non-directory then stop here.

		 */

		if (!d_is_dir(this)) {

			if (isdir) {

				dput(this);

				break;

			}

			stop = true;

		} else {

			/*

			 * Only makes sense to check opaque dir if this is not

			 * the lowermost layer.

			 */

			if (i < poe->numlower - 1 && ovl_is_opaquedir(this))

				stop = true;

		}



		stack[ctr].dentry = this;

		stack[ctr].mnt = lowerpath.mnt;