From bad61189780ec0592cacde01a0775cb98a30efdc Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Mon, 26 Mar 2012 12:54:24 +0200 Subject: [PATCH] vfs: split __lookup_hash Split __lookup_hash into two component functions: lookup_dcache - tries cached lookup, returns whether real lookup is needed lookup_real - calls i_op->lookup This eliminates code duplication between d_alloc_and_lookup() and d_inode_lookup(). Signed-off-by: Miklos Szeredi Signed-off-by: Al Viro --- fs/namei.c | 108 +++++++++++++++++++++++++------------------------------------ 1 file changed, 44 insertions(+), 64 deletions(-) diff --git a/fs/namei.c b/fs/namei.c index 5eeec56..fef80bf 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -1054,53 +1054,65 @@ static void follow_dotdot(struct nameidata *nd) } /* - * Allocate a dentry with name and parent, and perform a parent - * directory ->lookup on it. Returns the new dentry, or ERR_PTR - * on error. parent->d_inode->i_mutex must be held. d_lookup must - * have verified that no child exists while under i_mutex. + * This looks up the name in dcache, possibly revalidates the old dentry and + * allocates a new one if not found or not valid. In the need_lookup argument + * returns whether i_op->lookup is necessary. + * + * dir->d_inode->i_mutex must be held */ -static struct dentry *d_alloc_and_lookup(struct dentry *parent, - struct qstr *name, struct nameidata *nd) +static struct dentry *lookup_dcache(struct qstr *name, struct dentry *dir, + struct nameidata *nd, bool *need_lookup) { - struct inode *inode = parent->d_inode; struct dentry *dentry; - struct dentry *old; + int error; - /* Don't create child dentry for a dead directory. */ - if (unlikely(IS_DEADDIR(inode))) - return ERR_PTR(-ENOENT); + *need_lookup = false; + dentry = d_lookup(dir, name); + if (dentry) { + if (d_need_lookup(dentry)) { + *need_lookup = true; + } else if (dentry->d_flags & DCACHE_OP_REVALIDATE) { + error = d_revalidate(dentry, nd); + if (unlikely(error <= 0)) { + if (error < 0) { + dput(dentry); + return ERR_PTR(error); + } else if (!d_invalidate(dentry)) { + dput(dentry); + dentry = NULL; + } + } + } + } - dentry = d_alloc(parent, name); - if (unlikely(!dentry)) - return ERR_PTR(-ENOMEM); + if (!dentry) { + dentry = d_alloc(dir, name); + if (unlikely(!dentry)) + return ERR_PTR(-ENOMEM); - old = inode->i_op->lookup(inode, dentry, nd); - if (unlikely(old)) { - dput(dentry); - dentry = old; + *need_lookup = true; } return dentry; } /* - * We already have a dentry, but require a lookup to be performed on the parent - * directory to fill in d_inode. Returns the new dentry, or ERR_PTR on error. - * parent->d_inode->i_mutex must be held. d_lookup must have verified that no - * child exists while under i_mutex. + * Call i_op->lookup on the dentry. The dentry must be negative but may be + * hashed if it was pouplated with DCACHE_NEED_LOOKUP. + * + * dir->d_inode->i_mutex must be held */ -static struct dentry *d_inode_lookup(struct dentry *parent, struct dentry *dentry, - struct nameidata *nd) +static struct dentry *lookup_real(struct inode *dir, struct dentry *dentry, + struct nameidata *nd) { - struct inode *inode = parent->d_inode; struct dentry *old; /* Don't create child dentry for a dead directory. */ - if (unlikely(IS_DEADDIR(inode))) { + if (unlikely(IS_DEADDIR(dir))) { dput(dentry); return ERR_PTR(-ENOENT); } - old = inode->i_op->lookup(inode, dentry, nd); + old = dir->i_op->lookup(dir, dentry, nd); if (unlikely(old)) { dput(dentry); dentry = old; @@ -1111,46 +1123,14 @@ static struct dentry *d_inode_lookup(struct dentry *parent, struct dentry *dentr static struct dentry *__lookup_hash(struct qstr *name, struct dentry *base, struct nameidata *nd) { + bool need_lookup; struct dentry *dentry; - /* - * Don't bother with __d_lookup: callers are for creat as - * well as unlink, so a lot of the time it would cost - * a double lookup. - */ - dentry = d_lookup(base, name); + dentry = lookup_dcache(name, base, nd, &need_lookup); + if (!need_lookup) + return dentry; - if (dentry && d_need_lookup(dentry)) { - /* - * __lookup_hash is called with the parent dir's i_mutex already - * held, so we are good to go here. - */ - return d_inode_lookup(base, dentry, nd); - } - - if (dentry && (dentry->d_flags & DCACHE_OP_REVALIDATE)) { - int status = d_revalidate(dentry, nd); - if (unlikely(status <= 0)) { - /* - * The dentry failed validation. - * If d_revalidate returned 0 attempt to invalidate - * the dentry otherwise d_revalidate is asking us - * to return a fail status. - */ - if (status < 0) { - dput(dentry); - return ERR_PTR(status); - } else if (!d_invalidate(dentry)) { - dput(dentry); - dentry = NULL; - } - } - } - - if (!dentry) - dentry = d_alloc_and_lookup(base, name, nd); - - return dentry; + return lookup_real(base->d_inode, dentry, nd); } /* -- 2.7.4