[PATCH 60/61] sysfs: make directory dentries and inodes reclaimable

Greg Kroah-Hartman
2007-07-12T00:01:58Z

This patch makes dentries and inodes for sysfs directories
reclaimable.

* sysfs_notify() is modified to walk sysfs_dirent tree instead of
dentry tree.

* sysfs_update_file() and sysfs_chmod_file() use sysfs_get_dentry() to
grab the victim dentry.

* sysfs_rename_dir() and sysfs_move_dir() grab all dentries using
sysfs_get_dentry() on startup.

* Dentries for all shadowed directories are pinned in memory to serve
as lookup start point.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---
fs/sysfs/dir.c | 231 +++++++++++++++++++++++++++----------------------
fs/sysfs/file.c | 134 +++++++++++++----------------
fs/sysfs/mount.c | 2 +-
fs/sysfs/sysfs.h | 1 +
include/linux/sysfs.h | 1 -
5 files changed, 187 insertions(+), 182 deletions(-)

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index 9872112..aee966c 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -568,10 +568,10 @@ static void sysfs_drop_dentry(struct sysfs_dirent *sd)
spin_unlock(&dcache_lock);
spin_unlock(&sysfs_assoc_lock);

- dput(dentry);
- /* XXX: unpin if directory, this will go away soon */
- if (sysfs_type(sd) == SYSFS_DIR)
+ /* dentries for shadowed inodes are pinned, unpin */
+ if (dentry && sysfs_is_shadowed_inode(dentry->d_inode))
dput(dentry);
+ dput(dentry);

/* adjust nlink and update timestamp */
inode = ilookup(sysfs_sb, sd->s_ino);
@@ -686,69 +686,29 @@ struct sysfs_dirent *sysfs_get_dirent(struct sysfs_dirent *parent_sd,
static int create_dir(struct kobject *kobj, struct sysfs_dirent *parent_sd,
const char *name, struct sysfs_dirent **p_sd)
{
- struct dentry *parent = parent_sd->s_dentry;
- struct sysfs_addrm_cxt acxt;
- int error;
umode_t mode = S_IFDIR| S_IRWXU | S_IRUGO | S_IXUGO;
- struct dentry *dentry;
- struct inode *inode;
+ struct sysfs_addrm_cxt acxt;
struct sysfs_dirent *sd;

- sysfs_addrm_start(&acxt, parent_sd);
-
/* allocate */
- dentry = lookup_one_len(name, parent, strlen(name));
- if (IS_ERR(dentry)) {
- error = PTR_ERR(dentry);
- goto out_finish;
- }
-
- error = -EEXIST;
- if (dentry->d_inode)
- goto out_dput;
-
- error = -ENOMEM;
sd = sysfs_new_dirent(name, mode, SYSFS_DIR);
if (!sd)
- goto out_drop;
+ return -ENOMEM;
sd->s_elem.dir.kobj = kobj;

- inode = sysfs_get_inode(sd);
- if (!inode)
- goto out_sput;
-
- if (inode->i_state & I_NEW) {
- inode->i_op = &sysfs_dir_inode_operations;
- inode->i_fop = &sysfs_dir_operations;
- /* directory inodes start off with i_nlink == 2 (for ".") */
- inc_nlink(inode);
- }
-
/* link in */
- error = -EEXIST;
- if (sysfs_find_dirent(parent_sd, name))
- goto out_iput;
-
- sysfs_add_one(&acxt, sd);
- sysfs_link_sibling(sd);
- sysfs_instantiate(dentry, inode);
- sysfs_attach_dentry(sd, dentry);
-
- *p_sd = sd;
- error = 0;
- goto out_finish; /* pin directory dentry in core */
+ sysfs_addrm_start(&acxt, parent_sd);
+ if (!sysfs_find_dirent(parent_sd, name)) {
+ sysfs_add_one(&acxt, sd);
+ sysfs_link_sibling(sd);
+ }
+ if (sysfs_addrm_finish(&acxt)) {
+ *p_sd = sd;
+ return 0;
+ }

- out_iput:
- iput(inode);
- out_sput:
sysfs_put(sd);
- out_drop:
- d_drop(dentry);
- out_dput:
- dput(dentry);
- out_finish:
- sysfs_addrm_finish(&acxt);
- return error;
+ return -EEXIST;
}

int sysfs_create_subdir(struct kobject *kobj, const char *name,
@@ -785,6 +745,17 @@ int sysfs_create_dir(struct kobject *kobj,
return error;
}

+static int sysfs_count_nlink(struct sysfs_dirent *sd)
+{
+ struct sysfs_dirent *child;
+ int nr = 0;
+
+ for (child = sd->s_children; child; child = child->s_sibling)
+ if (sysfs_type(child) == SYSFS_DIR)
+ nr++;
+ return nr + 2;
+}
+
static struct dentry * sysfs_lookup(struct inode *dir, struct dentry *dentry,
struct nameidata *nd)
{
@@ -795,7 +766,7 @@ static struct dentry * sysfs_lookup(struct inode *dir, struct dentry *dentry,
int found = 0;

for (sd = parent_sd->s_children; sd; sd = sd->s_sibling) {
- if ((sysfs_type(sd) & SYSFS_NOT_PINNED) &&
+ if (sysfs_type(sd) &&
!strcmp(sd->s_name, dentry->d_name.name)) {
found = 1;
break;
@@ -816,6 +787,11 @@ static struct dentry * sysfs_lookup(struct inode *dir, struct dentry *dentry,
if (inode->i_state & I_NEW) {
/* initialize inode according to type */
switch (sysfs_type(sd)) {
+ case SYSFS_DIR:
+ inode->i_op = &sysfs_dir_inode_operations;
+ inode->i_fop = &sysfs_dir_operations;
+ inode->i_nlink = sysfs_count_nlink(sd);
+ break;
case SYSFS_KOBJ_ATTR:
inode->i_size = PAGE_SIZE;
inode->i_fop = &sysfs_file_operations;
@@ -876,7 +852,7 @@ static void __sysfs_remove_dir(struct sysfs_dirent *dir_sd)
while (*pos) {
struct sysfs_dirent *sd = *pos;

- if (sysfs_type(sd) && (sysfs_type(sd) & SYSFS_NOT_PINNED)) {
+ if (sysfs_type(sd) && sysfs_type(sd) != SYSFS_DIR) {
*pos = sd->s_sibling;
sd->s_sibling = NULL;
sysfs_remove_one(&acxt, sd);
@@ -912,14 +888,25 @@ int sysfs_rename_dir(struct kobject *kobj, struct sysfs_dirent *new_parent_sd,
const char *new_name)
{
struct sysfs_dirent *sd = kobj->sd;
- struct dentry *new_parent = new_parent_sd->s_dentry;
- struct dentry *new_dentry;
- char *dup_name;
+ struct dentry *new_parent = NULL;
+ struct dentry *old_dentry = NULL, *new_dentry = NULL;
+ const char *dup_name = NULL;
int error;

- if (!new_parent_sd)
- return -EFAULT;
+ /* get dentries */
+ old_dentry = sysfs_get_dentry(sd);
+ if (IS_ERR(old_dentry)) {
+ error = PTR_ERR(old_dentry);
+ goto out_dput;
+ }
+
+ new_parent = sysfs_get_dentry(new_parent_sd);
+ if (IS_ERR(new_parent)) {
+ error = PTR_ERR(new_parent);
+ goto out_dput;
+ }

+ /* lock new_parent and get dentry for new name */
mutex_lock(&new_parent->d_inode->i_mutex);

new_dentry = lookup_one_len(new_name, new_parent, strlen(new_name));
@@ -933,14 +920,14 @@ int sysfs_rename_dir(struct kobject *kobj, struct sysfs_dirent *new_parent_sd,
* shadows of the same directory
*/
error = -EINVAL;
- if (sd->s_parent->s_dentry->d_inode != new_parent->d_inode ||
+ if (old_dentry->d_parent->d_inode != new_parent->d_inode ||
new_dentry->d_parent->d_inode != new_parent->d_inode ||
- new_dentry == sd->s_dentry)
- goto out_dput;
+ old_dentry == new_dentry)
+ goto out_unlock;

error = -EEXIST;
if (new_dentry->d_inode)
- goto out_dput;
+ goto out_unlock;

/* rename kobject and sysfs_dirent */
error = -ENOMEM;
@@ -950,9 +937,9 @@ int sysfs_rename_dir(struct kobject *kobj, struct sysfs_dirent *new_parent_sd,

error = kobject_set_name(kobj, "%s", new_name);
if (error)
- goto out_free;
+ goto out_drop;

- kfree(sd->s_name);
+ dup_name = sd->s_name;
sd->s_name = new_name;

/* move under the new parent */
@@ -972,45 +959,58 @@ int sysfs_rename_dir(struct kobject *kobj, struct sysfs_dirent *new_parent_sd,
error = 0;
goto out_unlock;

- out_free:
- kfree(dup_name);
out_drop:
d_drop(new_dentry);
- out_dput:
- dput(new_dentry);
out_unlock:
mutex_unlock(&new_parent->d_inode->i_mutex);
+ out_dput:
+ kfree(dup_name);
+ dput(new_parent);
+ dput(old_dentry);
+ dput(new_dentry);
return error;
}

-int sysfs_move_dir(struct kobject *kobj, struct kobject *new_parent)
+int sysfs_move_dir(struct kobject *kobj, struct kobject *new_parent_kobj)
{
- struct dentry *old_parent_dentry, *new_parent_dentry, *new_dentry;
- struct sysfs_dirent *new_parent_sd, *sd;
+ struct sysfs_dirent *sd = kobj->sd;
+ struct sysfs_dirent *new_parent_sd;
+ struct dentry *old_parent, *new_parent = NULL;
+ struct dentry *old_dentry = NULL, *new_dentry = NULL;
int error;

- old_parent_dentry = kobj->parent ?
- kobj->parent->sd->s_dentry : sysfs_mount->mnt_sb->s_root;
- new_parent_dentry = new_parent ?
- new_parent->sd->s_dentry : sysfs_mount->mnt_sb->s_root;
+ BUG_ON(!sd->s_parent);
+ new_parent_sd = new_parent_kobj->sd ? new_parent_kobj->sd : &sysfs_root;
+
+ /* get dentries */
+ old_dentry = sysfs_get_dentry(sd);
+ if (IS_ERR(old_dentry)) {
+ error = PTR_ERR(old_dentry);
+ goto out_dput;
+ }
+ old_parent = sd->s_parent->s_dentry;
+
+ new_parent = sysfs_get_dentry(new_parent_sd);
+ if (IS_ERR(new_parent)) {
+ error = PTR_ERR(new_parent);
+ goto out_dput;
+ }

- if (old_parent_dentry->d_inode == new_parent_dentry->d_inode)
- return 0; /* nothing to move */
+ if (old_parent->d_inode == new_parent->d_inode) {
+ error = 0;
+ goto out_dput; /* nothing to move */
+ }
again:
- mutex_lock(&old_parent_dentry->d_inode->i_mutex);
- if (!mutex_trylock(&new_parent_dentry->d_inode->i_mutex)) {
- mutex_unlock(&old_parent_dentry->d_inode->i_mutex);
+ mutex_lock(&old_parent->d_inode->i_mutex);
+ if (!mutex_trylock(&new_parent->d_inode->i_mutex)) {
+ mutex_unlock(&old_parent->d_inode->i_mutex);
goto again;
}

- new_parent_sd = new_parent_dentry->d_fsdata;
- sd = kobj->sd;
-
- new_dentry = lookup_one_len(kobj->name, new_parent_dentry,
- strlen(kobj->name));
+ new_dentry = lookup_one_len(kobj->name, new_parent, strlen(kobj->name));
if (IS_ERR(new_dentry)) {
error = PTR_ERR(new_dentry);
- goto out;
+ goto out_unlock;
} else
error = 0;
d_add(new_dentry, NULL);
@@ -1027,10 +1027,14 @@ again:
sysfs_link_sibling(sd);

mutex_unlock(&sysfs_mutex);
-out:
- mutex_unlock(&new_parent_dentry->d_inode->i_mutex);
- mutex_unlock(&old_parent_dentry->d_inode->i_mutex);

+ out_unlock:
+ mutex_unlock(&new_parent->d_inode->i_mutex);
+ mutex_unlock(&old_parent->d_inode->i_mutex);
+ out_dput:
+ dput(new_parent);
+ dput(old_dentry);
+ dput(new_dentry);
return error;
}

@@ -1191,12 +1195,20 @@ static loff_t sysfs_dir_lseek(struct file * file, loff_t offset, int origin)
int sysfs_make_shadowed_dir(struct kobject *kobj,
void * (*follow_link)(struct dentry *, struct nameidata *))
{
+ struct dentry *dentry;
struct inode *inode;
struct inode_operations *i_op;

- inode = kobj->sd->s_dentry->d_inode;
- if (inode->i_op != &sysfs_dir_inode_operations)
+ /* get dentry for @kobj->sd, dentry of a shadowed dir is pinned */
+ dentry = sysfs_get_dentry(kobj->sd);
+ if (IS_ERR(dentry))
+ return PTR_ERR(dentry);
+
+ inode = dentry->d_inode;
+ if (inode->i_op != &sysfs_dir_inode_operations) {
+ dput(dentry);
return -EINVAL;
+ }

i_op = kmalloc(sizeof(*i_op), GFP_KERNEL);
if (!i_op)
@@ -1223,17 +1235,23 @@ int sysfs_make_shadowed_dir(struct kobject *kobj,

struct sysfs_dirent *sysfs_create_shadow_dir(struct kobject *kobj)
{
- struct dentry *dir = kobj->sd->s_dentry;
- struct inode *inode = dir->d_inode;
- struct dentry *parent = dir->d_parent;
- struct sysfs_dirent *parent_sd = parent->d_fsdata;
- struct dentry *shadow;
+ struct sysfs_dirent *parent_sd = kobj->sd->s_parent;
+ struct dentry *dir, *parent, *shadow;
+ struct inode *inode;
struct sysfs_dirent *sd;
struct sysfs_addrm_cxt acxt;

+ dir = sysfs_get_dentry(kobj->sd);
+ if (IS_ERR(dir)) {
+ sd = (void *)dir;
+ goto out;
+ }
+ parent = dir->d_parent;
+
+ inode = dir->d_inode;
sd = ERR_PTR(-EINVAL);
if (!sysfs_is_shadowed_inode(inode))
- goto out;
+ goto out_dput;

shadow = d_alloc(parent, &dir->d_name);
if (!shadow)
@@ -1258,12 +1276,15 @@ struct sysfs_dirent *sysfs_create_shadow_dir(struct kobject *kobj)

dget(shadow); /* Extra count - pin the dentry in core */

-out:
- return sd;
-nomem:
+ goto out_dput;
+
+ nomem:
dput(shadow);
sd = ERR_PTR(-ENOMEM);
- goto out;
+ out_dput:
+ dput(dir);
+ out:
+ return sd;
}

/**
diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index 69bacf1..cc49799 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -362,43 +362,22 @@ static unsigned int sysfs_poll(struct file *filp, poll_table *wait)
return POLLERR|POLLPRI;
}

-
-static struct dentry *step_down(struct dentry *dir, const char * name)
+void sysfs_notify(struct kobject *k, char *dir, char *attr)
{
- struct dentry * de;
-
- if (dir == NULL || dir->d_inode == NULL)
- return NULL;
-
- mutex_lock(&dir->d_inode->i_mutex);
- de = lookup_one_len(name, dir, strlen(name));
- mutex_unlock(&dir->d_inode->i_mutex);
- dput(dir);
- if (IS_ERR(de))
- return NULL;
- if (de->d_inode == NULL) {
- dput(de);
- return NULL;
- }
- return de;
-}
+ struct sysfs_dirent *sd = k->sd;

-void sysfs_notify(struct kobject * k, char *dir, char *attr)
-{
- struct dentry *de = k->sd->s_dentry;
- if (de)
- dget(de);
- if (de && dir)
- de = step_down(de, dir);
- if (de && attr)
- de = step_down(de, attr);
- if (de) {
- struct sysfs_dirent * sd = de->d_fsdata;
- if (sd)
- atomic_inc(&sd->s_event);
+ mutex_lock(&sysfs_mutex);
+
+ if (sd && dir)
+ sd = sysfs_find_dirent(sd, dir);
+ if (sd && attr)
+ sd = sysfs_find_dirent(sd, attr);
+ if (sd) {
+ atomic_inc(&sd->s_event);
wake_up_interruptible(&k->poll);
- dput(de);
}
+
+ mutex_unlock(&sysfs_mutex);
}
EXPORT_SYMBOL_GPL(sysfs_notify);

@@ -485,30 +464,31 @@ EXPORT_SYMBOL_GPL(sysfs_add_file_to_group);
*/
int sysfs_update_file(struct kobject * kobj, const struct attribute * attr)
{
- struct dentry *dir = kobj->sd->s_dentry;
- struct dentry * victim;
- int res = -ENOENT;
-
- mutex_lock(&dir->d_inode->i_mutex);
- victim = lookup_one_len(attr->name, dir, strlen(attr->name));
- if (!IS_ERR(victim)) {
- /* make sure dentry is really there */
- if (victim->d_inode &&
- (victim->d_parent->d_inode == dir->d_inode)) {
- victim->d_inode->i_mtime = CURRENT_TIME;
- fsnotify_modify(victim);
- res = 0;
- } else
- d_drop(victim);
-
- /**
- * Drop the reference acquired from lookup_one_len() above.
- */
- dput(victim);
+ struct sysfs_dirent *victim_sd = NULL;
+ struct dentry *victim = NULL;
+ int rc;
+
+ rc = -ENOENT;
+ victim_sd = sysfs_get_dirent(kobj->sd, attr->name);
+ if (!victim_sd)
+ goto out;
+
+ victim = sysfs_get_dentry(victim_sd);
+ if (IS_ERR(victim)) {
+ rc = PTR_ERR(victim);
+ victim = NULL;
+ goto out;
}
- mutex_unlock(&dir->d_inode->i_mutex);

- return res;
+ mutex_lock(&victim->d_inode->i_mutex);
+ victim->d_inode->i_mtime = CURRENT_TIME;
+ fsnotify_modify(victim);
+ mutex_unlock(&victim->d_inode->i_mutex);
+ rc = 0;
+ out:
+ dput(victim);
+ sysfs_put(victim_sd);
+ return rc;
}

@@ -521,30 +501,34 @@ int sysfs_update_file(struct kobject * kobj, const struct attribute * attr)
*/
int sysfs_chmod_file(struct kobject *kobj, struct attribute *attr, mode_t mode)
{
- struct dentry *dir = kobj->sd->s_dentry;
- struct dentry *victim;
+ struct sysfs_dirent *victim_sd = NULL;
+ struct dentry *victim = NULL;
struct inode * inode;
struct iattr newattrs;
- int res = -ENOENT;
-
- mutex_lock(&dir->d_inode->i_mutex);
- victim = lookup_one_len(attr->name, dir, strlen(attr->name));
- if (!IS_ERR(victim)) {
- if (victim->d_inode &&
- (victim->d_parent->d_inode == dir->d_inode)) {
- inode = victim->d_inode;
- mutex_lock(&inode->i_mutex);
- newattrs.ia_mode = (mode & S_IALLUGO) |
- (inode->i_mode & ~S_IALLUGO);
- newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
- res = notify_change(victim, &newattrs);
- mutex_unlock(&inode->i_mutex);
- }
- dput(victim);
+ int rc;
+
+ rc = -ENOENT;
+ victim_sd = sysfs_get_dirent(kobj->sd, attr->name);
+ if (!victim_sd)
+ goto out;
+
+ victim = sysfs_get_dentry(victim_sd);
+ if (IS_ERR(victim)) {
+ rc = PTR_ERR(victim);
+ victim = NULL;
+ goto out;
}
- mutex_unlock(&dir->d_inode->i_mutex);

- return res;
+ inode = victim->d_inode;
+ mutex_lock(&inode->i_mutex);
+ newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
+ newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
+ rc = notify_change(victim, &newattrs);
+ mutex_unlock(&inode->i_mutex);
+ out:
+ dput(victim);
+ sysfs_put(victim_sd);
+ return rc;
}
EXPORT_SYMBOL_GPL(sysfs_chmod_file);

diff --git a/fs/sysfs/mount.c b/fs/sysfs/mount.c
index 078537e..402cc35 100644
--- a/fs/sysfs/mount.c
+++ b/fs/sysfs/mount.c
@@ -24,7 +24,7 @@ static const struct super_operations sysfs_ops = {
.drop_inode = sysfs_delete_inode,
};

-static struct sysfs_dirent sysfs_root = {
+struct sysfs_dirent sysfs_root = {
.s_count = ATOMIC_INIT(1),
.s_flags = SYSFS_ROOT,
.s_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index 72530dc..6a37f23 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -52,6 +52,7 @@ struct sysfs_addrm_cxt {
};

extern struct vfsmount * sysfs_mount;
+extern struct sysfs_dirent sysfs_root;
extern struct kmem_cache *sysfs_dir_cachep;

extern struct dentry *sysfs_get_dentry(struct sysfs_dirent *sd);
diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h
index 4c43030..2f58ca1 100644
--- a/include/linux/sysfs.h
+++ b/include/linux/sysfs.h
@@ -81,7 +81,6 @@ struct sysfs_ops {
#define SYSFS_KOBJ_ATTR 0x0004
#define SYSFS_KOBJ_BIN_ATTR 0x0008
#define SYSFS_KOBJ_LINK 0x0020
-#define SYSFS_NOT_PINNED (SYSFS_KOBJ_ATTR | SYSFS_KOBJ_BIN_ATTR | SYSFS_KOBJ_LINK)
#define SYSFS_COPY_NAME (SYSFS_DIR | SYSFS_KOBJ_LINK)

#define SYSFS_FLAG_MASK ~SYSFS_TYPE_MASK
--
1.5.2.2