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sysfs: simply sysfs_get_dentry

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Now that we know the sysfs tree structure cannot change under us and
sysfs shadow support is dropped, sysfs_get_dentry() can be simplified
greatly.  It can just look up from the root and there's no need to
retry on failure.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Tejun Heo
2007-08-20 21:36:30 +09:00
committed by Greg Kroah-Hartman
parent 932ea2e374
commit e0712bbfd9
1 changed files with 16 additions and 75 deletions
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89
fs/sysfs/dir.c
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@@ -78,9 +78,8 @@ static void sysfs_unlink_sibling(struct sysfs_dirent *sd)
* @sd: sysfs_dirent of interest * @sd: sysfs_dirent of interest
* *
* Get dentry for @sd. Dentry is looked up if currently not * Get dentry for @sd. Dentry is looked up if currently not
* present. This function climbs sysfs_dirent tree till it * present. This function descends from the root looking up
* reaches a sysfs_dirent with valid dentry attached and descends * dentry for each step.
* down from there looking up dentry for each step.
* *
* LOCKING: * LOCKING:
* mutex_lock(sysfs_rename_mutex) * mutex_lock(sysfs_rename_mutex)
@@ -90,86 +89,28 @@ static void sysfs_unlink_sibling(struct sysfs_dirent *sd)
*/ */
struct dentry *sysfs_get_dentry(struct sysfs_dirent *sd) struct dentry *sysfs_get_dentry(struct sysfs_dirent *sd)
{ {
struct dentry *dentry = dget(sysfs_sb->s_root);
while (dentry->d_fsdata != sd) {
struct sysfs_dirent *cur; struct sysfs_dirent *cur;
struct dentry *parent_dentry, *dentry; struct dentry *parent;
int i, depth;
/* Find the first parent which has valid s_dentry and get the /* find the first ancestor which hasn't been looked up */
* dentry.
*/
mutex_lock(&sysfs_mutex);
restart0:
spin_lock(&sysfs_assoc_lock);
restart1:
spin_lock(&dcache_lock);
dentry = NULL;
depth = 0;
cur = sd; cur = sd;
while (!cur->s_dentry || !cur->s_dentry->d_inode) { while (cur->s_parent != dentry->d_fsdata)
if (cur->s_flags & SYSFS_FLAG_REMOVED) {
dentry = ERR_PTR(-ENOENT);
depth = 0;
break;
}
cur = cur->s_parent; 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--) {
/* find and get depth'th ancestor */
for (cur = sd, i = 0; cur && i < depth; i++)
cur = cur->s_parent;
/* This can happen if tree structure was modified due
* to move/rename. Restart.
*/
if (i != depth) {
dput(dentry);
goto restart0;
}
sysfs_get(cur);
mutex_unlock(&sysfs_mutex);
/* look it up */ /* look it up */
parent_dentry = dentry; parent = dentry;
mutex_lock(&parent_dentry->d_inode->i_mutex); mutex_lock(&parent->d_inode->i_mutex);
dentry = lookup_one_len_kern(cur->s_name, parent_dentry, dentry = lookup_one_len_kern(cur->s_name, parent,
strlen(cur->s_name)); strlen(cur->s_name));
mutex_unlock(&parent_dentry->d_inode->i_mutex); mutex_unlock(&parent->d_inode->i_mutex);
dput(parent_dentry); dput(parent);
if (IS_ERR(dentry)) { if (IS_ERR(dentry))
sysfs_put(cur); break;
return dentry;
} }
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) {
dput(dentry);
sysfs_put(cur);
goto restart1;
}
spin_unlock(&sysfs_assoc_lock);
sysfs_put(cur);
}
mutex_unlock(&sysfs_mutex);
return dentry; return dentry;
} }