dcache: Add case-insensitive support d_ci_add() routine (9403540c) · Commits · 戴 / test

fs/dcache.c

+102 −0

Original line number	Diff line number	Diff line
		@@ -1220,6 +1220,107 @@ struct dentry d_splice_alias(struct inode inode, struct dentry *dentry)
		return new;
		}

		/**
		* d_add_ci - lookup or allocate new dentry with case-exact name
		* @inode: the inode case-insensitive lookup has found
		* @dentry: the negative dentry that was passed to the parent's lookup func
		* @name: the case-exact name to be associated with the returned dentry
		*
		* This is to avoid filling the dcache with case-insensitive names to the
		* same inode, only the actual correct case is stored in the dcache for
		* case-insensitive filesystems.
		*
		* For a case-insensitive lookup match and if the the case-exact dentry
		* already exists in in the dcache, use it and return it.
		*
		* If no entry exists with the exact case name, allocate new dentry with
		* the exact case, and return the spliced entry.
		*/
		struct dentry d_add_ci(struct inode inode, struct dentry *dentry,
		struct qstr *name)
		{
		int error;
		struct dentry *found;
		struct dentry *new;

		/* Does a dentry matching the name exist already? */
		found = d_hash_and_lookup(dentry->d_parent, name);
		/* If not, create it now and return */
		if (!found) {
		new = d_alloc(dentry->d_parent, name);
		if (!new) {
		error = -ENOMEM;
		goto err_out;
		}
		found = d_splice_alias(inode, new);
		if (found) {
		dput(new);
		return found;
		}
		return new;
		}
		/* Matching dentry exists, check if it is negative. */
		if (found->d_inode) {
		if (unlikely(found->d_inode != inode)) {
		/* This can't happen because bad inodes are unhashed. */
		BUG_ON(!is_bad_inode(inode));
		BUG_ON(!is_bad_inode(found->d_inode));
		}
		/*
		* Already have the inode and the dentry attached, decrement
		* the reference count to balance the iget() done
		* earlier on. We found the dentry using d_lookup() so it
		* cannot be disconnected and thus we do not need to worry
		* about any NFS/disconnectedness issues here.
		*/
		iput(inode);
		return found;
		}
		/*
		* Negative dentry: instantiate it unless the inode is a directory and
		* has a 'disconnected' dentry (i.e. IS_ROOT and DCACHE_DISCONNECTED),
		* in which case d_move() that in place of the found dentry.
		*/
		if (!S_ISDIR(inode->i_mode)) {
		/* Not a directory; everything is easy. */
		d_instantiate(found, inode);
		return found;
		}
		spin_lock(&dcache_lock);
		if (list_empty(&inode->i_dentry)) {
		/*
		* Directory without a 'disconnected' dentry; we need to do
		* d_instantiate() by hand because it takes dcache_lock which
		* we already hold.
		*/
		list_add(&found->d_alias, &inode->i_dentry);
		found->d_inode = inode;
		spin_unlock(&dcache_lock);
		security_d_instantiate(found, inode);
		return found;
		}
		/*
		* Directory with a 'disconnected' dentry; get a reference to the
		* 'disconnected' dentry.
		*/
		new = list_entry(inode->i_dentry.next, struct dentry, d_alias);
		dget_locked(new);
		spin_unlock(&dcache_lock);
		/* Do security vodoo. */
		security_d_instantiate(found, inode);
		/* Move new in place of found. */
		d_move(new, found);
		/* Balance the iget() we did above. */
		iput(inode);
		/* Throw away found. */
		dput(found);
		/* Use new as the actual dentry. */
		return new;

		err_out:
		iput(inode);
		return ERR_PTR(error);
		}

		/**
		* d_lookup - search for a dentry
		@@ -2254,6 +2355,7 @@ EXPORT_SYMBOL(d_path);
		EXPORT_SYMBOL(d_prune_aliases);
		EXPORT_SYMBOL(d_rehash);
		EXPORT_SYMBOL(d_splice_alias);
		EXPORT_SYMBOL(d_add_ci);
		EXPORT_SYMBOL(d_validate);
		EXPORT_SYMBOL(dget_locked);
		EXPORT_SYMBOL(dput);

include/linux/dcache.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -230,6 +230,7 @@ extern void d_delete(struct dentry *);
		extern struct dentry * d_alloc(struct dentry , const struct qstr );
		extern struct dentry * d_alloc_anon(struct inode *);
		extern struct dentry * d_splice_alias(struct inode , struct dentry );
		extern struct dentry * d_add_ci(struct inode , struct dentry , struct qstr *);
		extern void shrink_dcache_sb(struct super_block *);
		extern void shrink_dcache_parent(struct dentry *);
		extern void shrink_dcache_for_umount(struct super_block *);

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