mirror of https://gitee.com/openkylin/linux.git
ovl: multi-layer lookup
Look up dentry in all relevant layers. Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
This commit is contained in:
Miklos Szeredi
parent
9d7459d834
commit
3d3c6b8939
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@ -333,82 +333,127 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
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unsigned int flags)
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{
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struct ovl_entry *oe;
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struct dentry *upperdir;
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struct path lowerdir;
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struct dentry *upperdentry = NULL;
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struct dentry *lowerdentry = NULL;
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struct ovl_entry *poe = dentry->d_parent->d_fsdata;
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struct path *stack = NULL;
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struct dentry *upperdir, *upperdentry = NULL;
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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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struct dentry *this, *prev = NULL;
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unsigned int i;
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int err;
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err = -ENOMEM;
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oe = ovl_alloc_entry(1);
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if (!oe)
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goto out;
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upperdir = ovl_dentry_upper(dentry->d_parent);
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ovl_path_lower(dentry->d_parent, &lowerdir);
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upperdir = ovl_upperdentry_dereference(poe);
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if (upperdir) {
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upperdentry = ovl_lookup_real(upperdir, &dentry->d_name);
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err = PTR_ERR(upperdentry);
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if (IS_ERR(upperdentry))
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goto out_put_dir;
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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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goto out;
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if (lowerdir.dentry && upperdentry) {
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if (ovl_is_whiteout(upperdentry)) {
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dput(upperdentry);
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upperdentry = NULL;
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oe->opaque = true;
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} else if (ovl_is_opaquedir(upperdentry)) {
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oe->opaque = true;
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/*
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* If this is not the lowermost layer, check whiteout and opaque
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* directory.
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*/
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if (poe->numlower && this) {
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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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upperopaque = true;
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} else if (ovl_is_opaquedir(this)) {
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upperopaque = true;
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}
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}
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}
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if (lowerdir.dentry && !oe->opaque) {
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lowerdentry = ovl_lookup_real(lowerdir.dentry, &dentry->d_name);
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err = PTR_ERR(lowerdentry);
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if (IS_ERR(lowerdentry))
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goto out_dput_upper;
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upperdentry = prev = this;
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}
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if (lowerdentry && upperdentry &&
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(!S_ISDIR(upperdentry->d_inode->i_mode) ||
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!S_ISDIR(lowerdentry->d_inode->i_mode))) {
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dput(lowerdentry);
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lowerdentry = NULL;
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oe->opaque = true;
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if (!upperopaque && 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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if (!stack)
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goto out_put_upper;
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}
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if (lowerdentry || upperdentry) {
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for (i = 0; !upperopaque && i < poe->numlower; i++) {
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bool opaque = false;
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struct path lowerpath = poe->lowerstack[i];
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opaque = false;
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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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goto out_put;
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if (!this)
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continue;
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/*
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* If this is not the lowermost layer, check whiteout and opaque
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* directory.
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*/
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if (i < poe->numlower - 1) {
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if (ovl_is_whiteout(this)) {
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dput(this);
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break;
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} else if (ovl_is_opaquedir(this)) {
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opaque = true;
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}
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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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* FIXME: check for opaqueness maybe better done in remove code.
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*/
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if (!S_ISDIR(this->d_inode->i_mode)) {
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opaque = true;
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} else if (prev && (!S_ISDIR(prev->d_inode->i_mode) ||
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!S_ISDIR(this->d_inode->i_mode))) {
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if (prev == upperdentry)
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upperopaque = true;
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dput(this);
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break;
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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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ctr++;
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prev = this;
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if (opaque)
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break;
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}
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oe = ovl_alloc_entry(ctr);
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err = -ENOMEM;
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if (!oe)
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goto out_put;
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if (upperdentry || ctr) {
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struct dentry *realdentry;
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realdentry = upperdentry ? upperdentry : lowerdentry;
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realdentry = upperdentry ? upperdentry : stack[0].dentry;
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err = -ENOMEM;
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inode = ovl_new_inode(dentry->d_sb, realdentry->d_inode->i_mode,
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oe);
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if (!inode)
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goto out_dput;
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goto out_free_oe;
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ovl_copyattr(realdentry->d_inode, inode);
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}
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oe->opaque = upperopaque;
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oe->__upperdentry = upperdentry;
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if (lowerdentry) {
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oe->lowerstack[0].dentry = lowerdentry;
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oe->lowerstack[0].mnt = lowerdir.mnt;
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} else {
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oe->numlower = 0;
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}
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memcpy(oe->lowerstack, stack, sizeof(struct path) * ctr);
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kfree(stack);
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dentry->d_fsdata = oe;
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d_add(dentry, inode);
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return NULL;
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out_dput:
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dput(lowerdentry);
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out_dput_upper:
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dput(upperdentry);
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out_put_dir:
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out_free_oe:
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kfree(oe);
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out_put:
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for (i = 0; i < ctr; i++)
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dput(stack[i].dentry);
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kfree(stack);
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out_put_upper:
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dput(upperdentry);
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out:
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return ERR_PTR(err);
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}
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