From mboxrd@z Thu Jan 1 00:00:00 1970 From: akpm@linux-foundation.org Subject: [patch 8/9] vfs: clean up real_lookup() Date: Tue, 17 Nov 2009 14:56:34 -0800 Message-ID: <200911172256.nAHMuY6e027763@imap1.linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Cc: linux-fsdevel@vger.kernel.org, akpm@linux-foundation.org, sage@newdream.net, adilger@sun.com, hch@infradead.org, raven@themaw.net, yehuda@newdream.net To: viro@zeniv.linux.org.uk Return-path: Received: from smtp1.linux-foundation.org ([140.211.169.13]:34352 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755504AbZKQXFh (ORCPT ); Tue, 17 Nov 2009 18:05:37 -0500 Sender: linux-fsdevel-owner@vger.kernel.org List-ID: From: Sage Weil Get rid of the goto by flipping the if (!result) over. Make the comments a bit more descriptive. Fix a few kernel style problems. No functional changes. Cc: Ian Kent Cc: Christoph Hellwig Cc: Al Viro Cc: Andreas Dilger Signed-off-by: Yehuda Sadeh Signed-off-by: Sage Weil Signed-off-by: Andrew Morton --- fs/namei.c | 65 ++++++++++++++++++++++++++------------------------- 1 file changed, 34 insertions(+), 31 deletions(-) diff -puN fs/namei.c~vfs-clean-up-real_lookup fs/namei.c --- a/fs/namei.c~vfs-clean-up-real_lookup +++ a/fs/namei.c @@ -469,19 +469,20 @@ ok: * This is called when everything else fails, and we actually have * to go to the low-level filesystem to find out what we should do.. * - * We get the directory semaphore, and after getting that we also + * We get the directory mutex, and after getting that we also * make sure that nobody added the entry to the dcache in the meantime.. * SMP-safe */ -static struct dentry * real_lookup(struct dentry * parent, struct qstr * name, struct nameidata *nd) +static struct dentry *real_lookup(struct dentry *parent, struct qstr *name, + struct nameidata *nd) { - struct dentry * result; + struct dentry *result, *dentry; struct inode *dir = parent->d_inode; mutex_lock(&dir->i_mutex); /* * First re-do the cached lookup just in case it was created - * while we waited for the directory semaphore.. + * while we waited for the directory mutex. * * FIXME! This could use version numbering or similar to * avoid unnecessary cache lookups. @@ -494,38 +495,40 @@ static struct dentry * real_lookup(struc * so doing d_lookup() (with seqlock), instead of lockfree __d_lookup */ result = d_lookup(parent, name); - if (!result) { - struct dentry *dentry; - -do_the_lookup: - /* Don't create child dentry for a dead directory. */ - result = ERR_PTR(-ENOENT); - if (IS_DEADDIR(dir)) - goto out_unlock; - - dentry = d_alloc(parent, name); - result = ERR_PTR(-ENOMEM); - if (dentry) { - result = dir->i_op->lookup(dir, dentry, nd); + if (result) { + /* + * The cache was re-populated while we waited on the + * mutex. We need to revalidate, this time while + * holding i_mutex (to avoid another race). + */ + if (result->d_op && result->d_op->d_revalidate) { + result = do_revalidate(result, nd); if (result) - dput(dentry); - else - result = dentry; + goto out_unlock; + /* + * The dentry was left behind invalid. Just + * do the lookup. + */ + } else { + goto out_unlock; } -out_unlock: - mutex_unlock(&dir->i_mutex); - return result; } - /* - * Uhhuh! Nasty case: the cache was re-populated while - * we waited on the semaphore. Need to revalidate. - */ - if (result->d_op && result->d_op->d_revalidate) { - result = do_revalidate(result, nd); - if (!result) - goto do_the_lookup; + /* Don't create child dentry for a dead directory. */ + result = ERR_PTR(-ENOENT); + if (IS_DEADDIR(dir)) + goto out_unlock; + + dentry = d_alloc(parent, name); + result = ERR_PTR(-ENOMEM); + if (dentry) { + result = dir->i_op->lookup(dir, dentry, nd); + if (result) + dput(dentry); + else + result = dentry; } +out_unlock: mutex_unlock(&dir->i_mutex); return result; } _