fuse: use d_materialise_unique()
Use d_materialise_unique() instead of d_splice_alias(). This allows dentry subtrees to be moved to a new place if there moved, even if something is referencing a dentry in the subtree (open fd, cwd, etc..). This will also allow us to drop a subtree if it is found to be replaced by something else. In this case the disconnected subtree can later be reconnected to its new location. d_materialise_unique() ensures that a directory entry only ever has one alias. We keep fc->inst_mutex around the calls for d_materialise_unique() on directories to prevent a race with mkdir "stealing" the inode. Signed-off-by: Miklos Szeredi <mszeredi@suse.cz> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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6497d160f6
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@ -267,26 +267,6 @@ int fuse_valid_type(int m)
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S_ISBLK(m) || S_ISFIFO(m) || S_ISSOCK(m);
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}
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/*
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* Add a directory inode to a dentry, ensuring that no other dentry
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* refers to this inode. Called with fc->inst_mutex.
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*/
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static struct dentry *fuse_d_add_directory(struct dentry *entry,
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struct inode *inode)
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{
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struct dentry *alias = d_find_alias(inode);
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if (alias && !(alias->d_flags & DCACHE_DISCONNECTED)) {
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/* This tries to shrink the subtree below alias */
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fuse_invalidate_entry(alias);
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dput(alias);
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if (!hlist_empty(&inode->i_dentry))
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return ERR_PTR(-EBUSY);
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} else {
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dput(alias);
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}
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return d_splice_alias(inode, entry);
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}
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int fuse_lookup_name(struct super_block *sb, u64 nodeid, struct qstr *name,
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struct fuse_entry_out *outarg, struct inode **inode)
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{
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@ -345,6 +325,24 @@ int fuse_lookup_name(struct super_block *sb, u64 nodeid, struct qstr *name,
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return err;
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}
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static struct dentry *fuse_materialise_dentry(struct dentry *dentry,
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struct inode *inode)
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{
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struct dentry *newent;
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if (inode && S_ISDIR(inode->i_mode)) {
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struct fuse_conn *fc = get_fuse_conn(inode);
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mutex_lock(&fc->inst_mutex);
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newent = d_materialise_unique(dentry, inode);
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mutex_unlock(&fc->inst_mutex);
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} else {
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newent = d_materialise_unique(dentry, inode);
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}
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return newent;
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}
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static struct dentry *fuse_lookup(struct inode *dir, struct dentry *entry,
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unsigned int flags)
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{
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@ -352,7 +350,6 @@ static struct dentry *fuse_lookup(struct inode *dir, struct dentry *entry,
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struct fuse_entry_out outarg;
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struct inode *inode;
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struct dentry *newent;
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struct fuse_conn *fc = get_fuse_conn(dir);
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bool outarg_valid = true;
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err = fuse_lookup_name(dir->i_sb, get_node_id(dir), &entry->d_name,
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@ -368,16 +365,10 @@ static struct dentry *fuse_lookup(struct inode *dir, struct dentry *entry,
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if (inode && get_node_id(inode) == FUSE_ROOT_ID)
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goto out_iput;
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if (inode && S_ISDIR(inode->i_mode)) {
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mutex_lock(&fc->inst_mutex);
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newent = fuse_d_add_directory(entry, inode);
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mutex_unlock(&fc->inst_mutex);
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err = PTR_ERR(newent);
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if (IS_ERR(newent))
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goto out_iput;
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} else {
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newent = d_splice_alias(inode, entry);
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}
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newent = fuse_materialise_dentry(entry, inode);
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err = PTR_ERR(newent);
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if (IS_ERR(newent))
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goto out_err;
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entry = newent ? newent : entry;
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if (outarg_valid)
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@ -1275,18 +1266,10 @@ static int fuse_direntplus_link(struct file *file,
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if (!inode)
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goto out;
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if (S_ISDIR(inode->i_mode)) {
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mutex_lock(&fc->inst_mutex);
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alias = fuse_d_add_directory(dentry, inode);
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mutex_unlock(&fc->inst_mutex);
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err = PTR_ERR(alias);
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if (IS_ERR(alias)) {
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iput(inode);
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goto out;
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}
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} else {
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alias = d_splice_alias(inode, dentry);
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}
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alias = fuse_materialise_dentry(dentry, inode);
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err = PTR_ERR(alias);
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if (IS_ERR(alias))
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goto out;
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if (alias) {
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dput(dentry);
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