linux-kernel - [PATCH 10/25] sysfs: Rewrite sysfs_get_dentry in terms of __sysfs_get

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Date:	Tue, 07 Aug 2007 15:18:27 -0600
From:	ebiederm@...ssion.com (Eric W. Biederman)
To:	Greg KH <greg@...ah.com>
Cc:	linux-kernel@...r.kernel.org, satyam@...radead.org,
	cornelia.huck@...ibm.com, stern@...land.harvard.edu,
	Tejun Heo <htejun@...il.com>,
	Linux Containers <containers@...ts.osdl.org>, gregkh@...e.de
Subject: [PATCH 10/25] sysfs: Rewrite sysfs_get_dentry in terms of __sysfs_get_dentry


This removes the last major user of s_dentry and makes
the locking in sysfs_get_dentry much simpler.  Hopefully
leading to more readable and maintainable code.

Signed-off-by: Eric W. Biederman <ebiederm@...ssion.com>
---
 fs/sysfs/dir.c |   23 ++++++-----------------
 1 files changed, 6 insertions(+), 17 deletions(-)

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index 59a9ce8..adb1b01 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -809,19 +809,15 @@ struct dentry *sysfs_get_dentry(struct sysfs_dirent *sd)
 	struct dentry *parent_dentry, *dentry;
 	int i, depth;
 
-	/* Find the first parent which has valid s_dentry and get the
-	 * dentry.
+	/* Find the first parent which has valid dentry.
 	 */
 	mutex_lock(&sysfs_mutex);
- restart0:
-	spin_lock(&sysfs_assoc_lock);
- restart1:
-	spin_lock(&dcache_lock);
+ restart:
 
 	dentry = NULL;
 	depth = 0;
 	cur = sd;
-	while (!cur->s_dentry || !cur->s_dentry->d_inode) {
+	while (!(dentry = __sysfs_get_dentry(sysfs_sb, cur))) {
 		if (cur->s_flags & SYSFS_FLAG_REMOVED) {
 			dentry = ERR_PTR(-ENOENT);
 			depth = 0;
@@ -830,11 +826,6 @@ struct dentry *sysfs_get_dentry(struct sysfs_dirent *sd)
 		cur = cur->s_parent;
 		depth++;
 	}
-	if (!IS_ERR(dentry))
-		dentry = dget_locked(cur->s_dentry);
-
-	spin_unlock(&dcache_lock);
-	spin_unlock(&sysfs_assoc_lock);
 
 	/* from the found dentry, look up depth times */
 	while (depth--) {
@@ -847,7 +838,7 @@ struct dentry *sysfs_get_dentry(struct sysfs_dirent *sd)
 		 */
 		if (i != depth) {
 			dput(dentry);
-			goto restart0;
+			goto restart;
 		}
 
 		sysfs_get(cur);
@@ -866,18 +857,16 @@ struct dentry *sysfs_get_dentry(struct sysfs_dirent *sd)
 		}
 
 		mutex_lock(&sysfs_mutex);
-		spin_lock(&sysfs_assoc_lock);
 
 		/* This, again, can happen if tree structure has
 		 * changed and we looked up the wrong thing.  Restart.
 		 */
-		if (cur->s_dentry != dentry) {
+		if (dentry->d_fsdata != cur) {
 			dput(dentry);
 			sysfs_put(cur);
-			goto restart1;
+			goto restart;
 		}
 
-		spin_unlock(&sysfs_assoc_lock);
 
 		sysfs_put(cur);
 	}
-- 
1.5.1.1.181.g2de0

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