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: Miklos Szeredi <mszeredi@redhat.com>
This commit is contained in:
Miklos Szeredi
parent
48fab5d7c7
commit
e28edc46b8
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@ -13,26 +13,13 @@
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#include "overlayfs.h"
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#include "ovl_entry.h"
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static struct dentry *ovl_lookup_real(struct dentry *dir,
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const struct qstr *name)
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{
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struct dentry *dentry;
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dentry = lookup_one_len_unlocked(name->name, dir, name->len);
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if (IS_ERR(dentry)) {
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if (PTR_ERR(dentry) == -ENOENT ||
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PTR_ERR(dentry) == -ENAMETOOLONG)
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dentry = NULL;
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} else if (!dentry->d_inode) {
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dput(dentry);
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dentry = NULL;
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} else if (ovl_dentry_weird(dentry)) {
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dput(dentry);
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/* Don't support traversing automounts and other weirdness */
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dentry = ERR_PTR(-EREMOTE);
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}
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return dentry;
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}
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struct ovl_lookup_data {
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struct qstr name;
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bool is_dir;
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bool opaque;
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bool stop;
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bool last;
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};
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static bool ovl_is_opaquedir(struct dentry *dentry)
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{
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@ -49,6 +36,64 @@ static bool ovl_is_opaquedir(struct dentry *dentry)
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return false;
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}
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static int ovl_lookup_single(struct dentry *base, struct ovl_lookup_data *d,
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const char *name, unsigned int namelen,
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struct dentry **ret)
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{
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struct dentry *this;
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int err;
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this = lookup_one_len_unlocked(name, base, namelen);
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if (IS_ERR(this)) {
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err = PTR_ERR(this);
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this = NULL;
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if (err == -ENOENT || err == -ENAMETOOLONG)
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goto out;
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goto out_err;
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}
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if (!this->d_inode)
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goto put_and_out;
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if (ovl_dentry_weird(this)) {
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/* Don't support traversing automounts and other weirdness */
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err = -EREMOTE;
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goto out_err;
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}
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if (ovl_is_whiteout(this)) {
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d->stop = d->opaque = true;
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goto put_and_out;
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}
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if (!d_can_lookup(this)) {
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d->stop = true;
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if (d->is_dir)
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goto put_and_out;
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goto out;
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}
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d->is_dir = true;
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if (!d->last && ovl_is_opaquedir(this)) {
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d->stop = d->opaque = true;
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goto out;
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}
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out:
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*ret = this;
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return 0;
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put_and_out:
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dput(this);
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this = NULL;
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goto out;
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out_err:
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dput(this);
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return err;
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}
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static int ovl_lookup_layer(struct dentry *base, struct ovl_lookup_data *d,
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struct dentry **ret)
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{
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return ovl_lookup_single(base, d, d->name.name, d->name.len, ret);
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}
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/*
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* Returns next layer in stack starting from top.
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* Returns -1 if this is the last layer.
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@ -82,11 +127,16 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
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unsigned int ctr = 0;
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struct inode *inode = NULL;
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bool upperopaque = false;
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bool stop = false;
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bool isdir = false;
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struct dentry *this;
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unsigned int i;
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int err;
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struct ovl_lookup_data d = {
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.name = dentry->d_name,
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.is_dir = false,
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.opaque = false,
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.stop = false,
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.last = !poe->numlower,
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};
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if (dentry->d_name.len > ofs->namelen)
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return ERR_PTR(-ENAMETOOLONG);
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@ -94,70 +144,36 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
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old_cred = ovl_override_creds(dentry->d_sb);
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upperdir = ovl_upperdentry_dereference(poe);
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if (upperdir) {
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this = ovl_lookup_real(upperdir, &dentry->d_name);
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err = PTR_ERR(this);
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if (IS_ERR(this))
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err = ovl_lookup_layer(upperdir, &d, &upperdentry);
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if (err)
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goto out;
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if (this) {
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if (unlikely(ovl_dentry_remote(this))) {
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dput(this);
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err = -EREMOTE;
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goto out;
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}
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if (ovl_is_whiteout(this)) {
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dput(this);
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this = NULL;
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stop = upperopaque = true;
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} else if (!d_is_dir(this)) {
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stop = true;
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} else {
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isdir = true;
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if (poe->numlower && ovl_is_opaquedir(this))
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stop = upperopaque = true;
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}
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if (upperdentry && unlikely(ovl_dentry_remote(upperdentry))) {
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dput(upperdentry);
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err = -EREMOTE;
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goto out;
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}
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upperdentry = this;
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upperopaque = d.opaque;
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}
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if (!stop && poe->numlower) {
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if (!d.stop && poe->numlower) {
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err = -ENOMEM;
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stack = kcalloc(poe->numlower, sizeof(struct path), GFP_KERNEL);
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stack = kcalloc(poe->numlower, sizeof(struct path),
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GFP_TEMPORARY);
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if (!stack)
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goto out_put_upper;
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}
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for (i = 0; !stop && i < poe->numlower; i++) {
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for (i = 0; !d.stop && i < poe->numlower; i++) {
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struct path lowerpath = poe->lowerstack[i];
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this = ovl_lookup_real(lowerpath.dentry, &dentry->d_name);
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err = PTR_ERR(this);
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if (IS_ERR(this))
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d.last = i == poe->numlower - 1;
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err = ovl_lookup_layer(lowerpath.dentry, &d, &this);
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if (err)
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goto out_put;
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if (!this)
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continue;
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if (ovl_is_whiteout(this)) {
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dput(this);
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break;
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}
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/*
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* If this is a non-directory then stop here.
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*/
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if (!d_is_dir(this)) {
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if (isdir) {
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dput(this);
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break;
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}
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stop = true;
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} else {
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/*
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* Only makes sense to check opaque dir if this is not
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* the lowermost layer.
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*/
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if (i < poe->numlower - 1 && ovl_is_opaquedir(this))
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stop = true;
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}
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stack[ctr].dentry = this;
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stack[ctr].mnt = lowerpath.mnt;
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