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sysfs: make directory dentries and inodes reclaimable
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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>
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Tejun Heo authored and Greg Kroah-Hartman committed Jul 11, 2007
1 parent 53e0ae9 commit 5122503
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Showing 5 changed files with 187 additions and 182 deletions.
231 changes: 126 additions & 105 deletions fs/sysfs/dir.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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);
Expand Down Expand Up @@ -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,
Expand Down Expand Up @@ -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)
{
Expand All @@ -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;
Expand All @@ -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;
Expand Down Expand Up @@ -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);
Expand Down Expand Up @@ -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));
Expand All @@ -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;
Expand All @@ -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 */
Expand All @@ -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);
Expand All @@ -1027,10 +1027,14 @@ int sysfs_move_dir(struct kobject *kobj, struct kobject *new_parent)
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;
}

Expand Down Expand Up @@ -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)
Expand All @@ -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)
Expand All @@ -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;
}

/**
Expand Down
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