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Commit 5835f339 authored by Miklos Szeredi's avatar Miklos Szeredi Committed by Al Viro
Browse files

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: default avatarMiklos Szeredi <mszeredi@suse.cz>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 6497d160

fs/fuse/dir.c

+26 −43
Original line number Diff line number Diff line
@@ -267,26 +267,6 @@ int fuse_valid_type(int m) 
		S_ISBLK(m) || S_ISFIFO(m) || S_ISSOCK(m);

}



/*

 * Add a directory inode to a dentry, ensuring that no other dentry

 * refers to this inode.  Called with fc->inst_mutex.

 */

static struct dentry *fuse_d_add_directory(struct dentry *entry,

					   struct inode *inode)

{

	struct dentry *alias = d_find_alias(inode);

	if (alias && !(alias->d_flags & DCACHE_DISCONNECTED)) {

		/* This tries to shrink the subtree below alias */

		fuse_invalidate_entry(alias);

		dput(alias);

		if (!hlist_empty(&inode->i_dentry))

			return ERR_PTR(-EBUSY);

	} else {

		dput(alias);

	}

	return d_splice_alias(inode, entry);

}



int fuse_lookup_name(struct super_block *sb, u64 nodeid, struct qstr *name,

		     struct fuse_entry_out *outarg, struct inode **inode)

{
@@ -345,6 +325,24 @@ int fuse_lookup_name(struct super_block *sb, u64 nodeid, struct qstr *name, 
	return err;

}



static struct dentry *fuse_materialise_dentry(struct dentry *dentry,

					      struct inode *inode)

{

	struct dentry *newent;



	if (inode && S_ISDIR(inode->i_mode)) {

		struct fuse_conn *fc = get_fuse_conn(inode);



		mutex_lock(&fc->inst_mutex);

		newent = d_materialise_unique(dentry, inode);

		mutex_unlock(&fc->inst_mutex);

	} else {

		newent = d_materialise_unique(dentry, inode);

	}



	return newent;

}



static struct dentry *fuse_lookup(struct inode *dir, struct dentry *entry,

				  unsigned int flags)

{
@@ -352,7 +350,6 @@ static struct dentry *fuse_lookup(struct inode *dir, struct dentry *entry, 
	struct fuse_entry_out outarg;

	struct inode *inode;

	struct dentry *newent;

	struct fuse_conn *fc = get_fuse_conn(dir);

	bool outarg_valid = true;



	err = fuse_lookup_name(dir->i_sb, get_node_id(dir), &entry->d_name,
@@ -368,16 +365,10 @@ static struct dentry *fuse_lookup(struct inode *dir, struct dentry *entry, 
	if (inode && get_node_id(inode) == FUSE_ROOT_ID)

		goto out_iput;



	if (inode && S_ISDIR(inode->i_mode)) {

		mutex_lock(&fc->inst_mutex);

		newent = fuse_d_add_directory(entry, inode);

		mutex_unlock(&fc->inst_mutex);

	newent = fuse_materialise_dentry(entry, inode);

	err = PTR_ERR(newent);

	if (IS_ERR(newent))

			goto out_iput;

	} else {

		newent = d_splice_alias(inode, entry);

	}

		goto out_err;



	entry = newent ? newent : entry;

	if (outarg_valid)
@@ -1275,18 +1266,10 @@ static int fuse_direntplus_link(struct file *file, 
	if (!inode)

		goto out;



	if (S_ISDIR(inode->i_mode)) {

		mutex_lock(&fc->inst_mutex);

		alias = fuse_d_add_directory(dentry, inode);

		mutex_unlock(&fc->inst_mutex);

	alias = fuse_materialise_dentry(dentry, inode);

	err = PTR_ERR(alias);

		if (IS_ERR(alias)) {

			iput(inode);

	if (IS_ERR(alias))

		goto out;

		}

	} else {

		alias = d_splice_alias(inode, dentry);

	}



	if (alias) {

		dput(dentry);