netdev - [PATCH 07/15] sysfs: sysfs_chmod_file handle multiple superblocks

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Message-ID: <m14p76ih9a.fsf_-_@frodo.ebiederm.org>
Date:	Thu, 03 Jul 2008 18:13:05 -0700
From:	ebiederm@...ssion.com (Eric W. Biederman)
To:	Greg Kroah-Hartman <gregkh@...e.de>,
	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Tejun Heo <htejun@...il.com>, Daniel Lezcano <dlezcano@...ibm.com>,
	linux-kernel@...r.kernel.org, Al Viro <viro@....linux.org.uk>,
	Linux Containers <containers@...ts.osdl.org>,
	Benjamin Thery <benjamin.thery@...l.net>,
	<netdev@...r.kernel.org>
Subject: [PATCH 07/15] sysfs: sysfs_chmod_file handle multiple superblocks


Teach sysfs_chmod_file how to handle multiple sysfs superblocks.
Since we only have one inode per sd the only thing we have to deal
with is multiple dentries for sending fs notifications.  This might
dup the inode notifications oh well.

Signed-off-by: Eric W. Biederman <ebiederm@...ssion.com>
---
 fs/sysfs/file.c |   39 +++++++++++++++++++++++++--------------
 1 files changed, 25 insertions(+), 14 deletions(-)

diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index 1304b3a..5955ae9 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -574,8 +574,8 @@ EXPORT_SYMBOL_GPL(sysfs_add_file_to_group);
 int sysfs_chmod_file(struct kobject *kobj, struct attribute *attr, mode_t mode)
 {
 	struct sysfs_dirent *victim_sd = NULL;
-	struct dentry *victim = NULL;
-	struct inode * inode;
+	struct super_block *sb;
+	struct inode * inode = NULL;
 	struct iattr newattrs;
 	int rc;
 
@@ -584,31 +584,42 @@ int sysfs_chmod_file(struct kobject *kobj, struct attribute *attr, mode_t mode)
 	if (!victim_sd)
 		goto out;
 
-	mutex_lock(&sysfs_rename_mutex);
-	victim = sysfs_get_dentry(sysfs_sb, victim_sd);
-	mutex_unlock(&sysfs_rename_mutex);
-	if (IS_ERR(victim)) {
-		rc = PTR_ERR(victim);
-		victim = NULL;
-		goto out;
-	}
-
-	inode = victim->d_inode;
+	rc = -ENOENT;
+	mutex_lock(&sysfs_mutex);
+	inode = sysfs_get_inode(victim_sd);
+	mutex_unlock(&sysfs_mutex);
+	if (!inode)
+ 		goto out;
 
+	mutex_lock(&sysfs_rename_mutex);
+	sysfs_grab_supers();
 	mutex_lock(&inode->i_mutex);
 
 	newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
 	newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
 	newattrs.ia_ctime = current_fs_time(inode->i_sb);
 	rc = sysfs_sd_setattr(victim_sd, inode, &newattrs);
+	if (rc)
+		goto out_unlock;
+
+	list_for_each_entry(sb, &sysfs_fs_type.fs_supers, s_instances) {
+		/* Ignore it when the dentry does not exist on the
+		 * target superblock.
+		 */
+		struct dentry *	victim = sysfs_get_dentry(sb, victim_sd);
+		if (IS_ERR(victim))
+			continue;
 
-	if (rc == 0) {
 		fsnotify_change(victim, newattrs.ia_valid);
+		dput(victim);
 	}
 
+ out_unlock:
 	mutex_unlock(&inode->i_mutex);
+	sysfs_release_supers();
+	mutex_unlock(&sysfs_rename_mutex);
  out:
-	dput(victim);
+	iput(inode);
 	sysfs_put(victim_sd);
 	return rc;
 }
-- 
1.5.3.rc6.17.g1911

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