From: Maneesh Soni <maneesh@in.ibm.com>
=> changes in version 0.6
o Re-diffed for 2.6.6-mm3
o Provided protection against vulneribility of parent going before
the sysfs file being removed in sysfs_hash_and_remove(). Now it uses
s_dentry field to check if the file dentry is vaild instead of doing a
lookup. A new routine sysfs_drop_dentry() is introduced for this purpose.
=> changes in version 0.5
o Cahnges to accomodate latest sysfs changes basically using
sysfs_get_kobject() while opening sysfs files.
=> changes in version 0.4
o Made necessary changes for checking DCACHE_SYSFS_CONNECTED flag while
opening the sysfs file in check_perm() and a few changes in variable names
=> changes in version 0.3
o Nil, just re-diffed
=> changes in version 0.2
o Nil, just re-diffed
=> Changes:
o Removed the extra kobject_get from sysfs_release()
=======================================================
o sysfs_create_file() will just link a new sysfs_dirent() structure representing
the attribute file to the kobject's s_children list.
o in sysfs_create() we take extra ref. only for dentries corresponding to
non-regular files or in other words pin only non-leaf dentries.
Signed-off-by: Andrew Morton <akpm@osdl.org>
---
25-akpm/fs/sysfs/file.c | 65 ++++++++++++++++++++++-----------------------
25-akpm/fs/sysfs/inode.c | 67 +++++++++++++++++++++++++++++++----------------
2 files changed, 77 insertions(+), 55 deletions(-)
diff -puN fs/sysfs/file.c~sysfs-leaves-file fs/sysfs/file.c
--- 25/fs/sysfs/file.c~sysfs-leaves-file 2004-06-28 20:25:34.194230152 -0700
+++ 25-akpm/fs/sysfs/file.c 2004-06-28 20:25:34.199229392 -0700
@@ -9,14 +9,6 @@
#include "sysfs.h"
-static struct file_operations sysfs_file_operations;
-
-static int init_file(struct inode * inode)
-{
- inode->i_size = PAGE_SIZE;
- inode->i_fop = &sysfs_file_operations;
- return 0;
-}
#define to_subsys(k) container_of(k,struct subsystem,kset.kobj)
#define to_sattr(a) container_of(a,struct subsys_attribute,attr)
@@ -77,8 +69,10 @@ struct sysfs_buffer {
*/
static int fill_read_buffer(struct file * file, struct sysfs_buffer * buffer)
{
- struct attribute * attr = file->f_dentry->d_fsdata;
- struct kobject * kobj = file->f_dentry->d_parent->d_fsdata;
+ struct sysfs_dirent * attr_sd = file->f_dentry->d_fsdata;
+ struct attribute * attr = attr_sd->s_element;
+ struct sysfs_dirent * kobj_sd = file->f_dentry->d_parent->d_fsdata;
+ struct kobject * kobj = kobj_sd->s_element;
struct sysfs_ops * ops = buffer->ops;
int ret = 0;
ssize_t count;
@@ -135,6 +129,9 @@ static int flush_read_buffer(struct sysf
* is in the file's ->d_fsdata. The target object is in the directory's
* ->d_fsdata.
*
+ * It is safe to use ->d_parent->d_fsdata as both dentry and the kobject
+ * are pinned in ->open().
+ *
* We call fill_read_buffer() to allocate and fill the buffer from the
* object's show() method exactly once (if the read is happening from
* the beginning of the file). That should fill the entire buffer with
@@ -199,8 +196,10 @@ fill_write_buffer(struct sysfs_buffer *
static int
flush_write_buffer(struct file * file, struct sysfs_buffer * buffer, size_t count)
{
- struct attribute * attr = file->f_dentry->d_fsdata;
- struct kobject * kobj = file->f_dentry->d_parent->d_fsdata;
+ struct sysfs_dirent * attr_sd = file->f_dentry->d_fsdata;
+ struct attribute * attr = attr_sd->s_element;
+ struct sysfs_dirent * kobj_sd = file->f_dentry->d_parent->d_fsdata;
+ struct kobject * kobj = kobj_sd->s_element;
struct sysfs_ops * ops = buffer->ops;
return ops->store(kobj,attr,buffer->page,count);
@@ -240,7 +239,8 @@ sysfs_write_file(struct file *file, cons
static int check_perm(struct inode * inode, struct file * file)
{
struct kobject *kobj = sysfs_get_kobject(file->f_dentry->d_parent);
- struct attribute * attr = file->f_dentry->d_fsdata;
+ struct sysfs_dirent * attr_sd = file->f_dentry->d_fsdata;
+ struct attribute * attr = attr_sd->s_element;
struct sysfs_buffer * buffer;
struct sysfs_ops * ops = NULL;
int error = 0;
@@ -321,8 +321,10 @@ static int sysfs_open_file(struct inode
static int sysfs_release(struct inode * inode, struct file * filp)
{
- struct kobject * kobj = filp->f_dentry->d_parent->d_fsdata;
- struct attribute * attr = filp->f_dentry->d_fsdata;
+ struct sysfs_dirent * attr_sd = filp->f_dentry->d_fsdata;
+ struct attribute * attr = attr_sd->s_element;
+ struct sysfs_dirent * kobj_sd = filp->f_dentry->d_parent->d_fsdata;
+ struct kobject * kobj = kobj_sd->s_element;
struct sysfs_buffer * buffer = filp->private_data;
if (kobj)
@@ -337,7 +339,7 @@ static int sysfs_release(struct inode *
return 0;
}
-static struct file_operations sysfs_file_operations = {
+struct file_operations sysfs_file_operations = {
.read = sysfs_read_file,
.write = sysfs_write_file,
.llseek = generic_file_llseek,
@@ -346,23 +348,20 @@ static struct file_operations sysfs_file
};
-int sysfs_add_file(struct dentry * dir, const struct attribute * attr)
+int sysfs_add_file(struct dentry * parent, const struct attribute * attr, int t)
{
- struct dentry * dentry;
- int error;
+ struct sysfs_dirent * sd;
+ struct sysfs_dirent * parent_sd = parent->d_fsdata;
+ int error = 0;
+
+ down(&parent->d_inode->i_sem);
+ sd = sysfs_new_dirent(parent_sd, (void *) attr, t);
+ if (!sd)
+ error = -ENOMEM;
+ else
+ sd->s_mode = (attr->mode & S_IALLUGO) | S_IFREG ;
+ up(&parent->d_inode->i_sem);
- down(&dir->d_inode->i_sem);
- dentry = sysfs_get_dentry(dir,attr->name);
- if (!IS_ERR(dentry)) {
- error = sysfs_create(dentry,
- (attr->mode & S_IALLUGO) | S_IFREG,
- init_file);
- if (!error)
- dentry->d_fsdata = (void *)attr;
- dput(dentry);
- } else
- error = PTR_ERR(dentry);
- up(&dir->d_inode->i_sem);
return error;
}
@@ -375,8 +374,8 @@ int sysfs_add_file(struct dentry * dir,
int sysfs_create_file(struct kobject * kobj, const struct attribute * attr)
{
- if (kobj && attr)
- return sysfs_add_file(kobj->dentry,attr);
+ if (kobj && kobj->dentry && attr)
+ return sysfs_add_file(kobj->dentry, attr, SYSFS_KOBJ_ATTR);
return -EINVAL;
}
diff -puN fs/sysfs/inode.c~sysfs-leaves-file fs/sysfs/inode.c
--- 25/fs/sysfs/inode.c~sysfs-leaves-file 2004-06-28 20:25:34.195230000 -0700
+++ 25-akpm/fs/sysfs/inode.c 2004-06-28 20:25:34.200229240 -0700
@@ -11,6 +11,8 @@
#include <linux/pagemap.h>
#include <linux/namei.h>
#include <linux/backing-dev.h>
+#include "sysfs.h"
+
extern struct super_block * sysfs_sb;
static struct address_space_operations sysfs_aops = {
@@ -66,7 +68,8 @@ int sysfs_create(struct dentry * dentry,
error = init(inode);
if (!error) {
d_instantiate(dentry, inode);
- dget(dentry); /* Extra count - pin the dentry in core */
+ if (S_ISDIR(mode))
+ dget(dentry); /* pin only directory dentry in core */
} else
iput(inode);
Done:
@@ -88,31 +91,51 @@ struct dentry * sysfs_get_dentry(struct
return lookup_hash(&qstr,parent);
}
+static struct sysfs_dirent * sysfs_find_dirent(struct sysfs_dirent * parent_sd,
+ const char * name)
+{
+ struct sysfs_dirent *sd;
+
+ list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
+ if (sd->s_element) {
+ if (!strcmp(sysfs_get_name(sd), name))
+ return sd;
+ }
+ }
+ return NULL;
+}
+
+/* Unhashes the dentry corresponding to given sysfs_dirent
+ * Called with parent inode's i_sem held.
+ */
+void sysfs_drop_dentry(struct sysfs_dirent * sd, struct dentry * parent)
+{
+ struct dentry * dentry = sd->s_dentry;
+
+ if (dentry) {
+ spin_lock(&dcache_lock);
+ dget_locked(dentry);
+ if (!(d_unhashed(dentry) && dentry->d_inode)) {
+ __d_drop(dentry);
+ spin_unlock(&dcache_lock);
+ simple_unlink(parent->d_inode, dentry);
+ } else {
+ spin_unlock(&dcache_lock);
+ dput(dentry);
+ }
+ }
+}
+
void sysfs_hash_and_remove(struct dentry * dir, const char * name)
{
- struct dentry * victim;
+ struct sysfs_dirent * sd;
down(&dir->d_inode->i_sem);
- victim = sysfs_get_dentry(dir,name);
- if (!IS_ERR(victim)) {
- /* make sure dentry is really there */
- if (victim->d_inode &&
- (victim->d_parent->d_inode == dir->d_inode)) {
- pr_debug("sysfs: Removing %s (%d)\n", victim->d_name.name,
- atomic_read(&victim->d_count));
-
- d_drop(victim);
- /* release the target kobject in case of
- * a symlink
- */
- if (S_ISLNK(victim->d_inode->i_mode))
- kobject_put(victim->d_fsdata);
- simple_unlink(dir->d_inode,victim);
- }
- /*
- * Drop reference from sysfs_get_dentry() above.
- */
- dput(victim);
+ sd = sysfs_find_dirent(dir->d_fsdata, name);
+ if (sd) {
+ list_del_init(&sd->s_sibling);
+ sysfs_drop_dentry(sd, dir);
+ sysfs_put(sd);
}
up(&dir->d_inode->i_sem);
}
_