[PATCH 04/10] sysfs: Implement __sysfs_get_dentry

Eric W. Biederman
2007-12-01T09:21:51Z

This function is similar but much simpler to sysfs_get_dentry
returns a sysfs dentry if one curently exists.

This requires less locking the sysfs_get_dentry and which
makes it preferable in some contexts.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
---
fs/sysfs/dir.c | 38 ++++++++++++++++++++++++++++++++++++++
1 files changed, 38 insertions(+), 0 deletions(-)

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index cff2b12..3ec9040 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -764,6 +764,44 @@ void sysfs_remove_dir(struct kobject * kobj)
__sysfs_remove_dir(sd);
}

+/**
+ * __sysfs_get_dentry - get dentry for the given sysfs_dirent
+ * @sb: superblock of the dentry to return
+ * @sd: sysfs_dirent of interest
+ *
+ * Get dentry for @sd. Only return a dentry if one currently
+ * exists.
+ *
+ * LOCKING:
+ * Kernel thread context (may sleep)
+ *
+ * RETURNS:
+ * Pointer to found dentry on success, NULL on failure.
+ */
+static struct dentry *__sysfs_get_dentry(struct super_block *sb, struct sysfs_dirent *sd)
+{
+ struct inode *inode;
+ struct dentry *dentry = NULL;
+
+ inode = ilookup5_nowait(sysfs_sb, sd->s_ino, sysfs_ilookup_test, sd);
+ if (inode && !(inode->i_state & I_NEW)) {
+ struct dentry *alias;
+ spin_lock(&dcache_lock);
+ list_for_each_entry(alias, &inode->i_dentry, d_alias) {
+ if (!IS_ROOT(alias) && d_unhashed(alias))
+ continue;
+ if (alias->d_sb != sb)
+ continue;
+ dentry = alias;
+ dget_locked(dentry);
+ break;
+ }
+ spin_unlock(&dcache_lock);
+ }
+ iput(inode);
+ return dentry;
+}
+
int sysfs_rename_dir(struct kobject * kobj, const char *new_name)
{
struct sysfs_dirent *sd = kobj->sd;
--
1.5.3.rc6.17.g1911