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_remove_dir(). There os less chance
happening this here, but still it will have some code clarity. 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 Changed ->read_dir & ->lseek logic. The ->read_dir and ->lseek
logic is now based on the sysfs_dirent tree instead of dentry
based tree. Now we don't have to dget/dput children while
opening a dir. The earlier logic was wrong in the sense as we might
end up in doing dput() for dentrys which were not opened by us.
o Code changes to accomodate latest sysfs changes like in sysfs_rename_dir,
sysfs_remove_dir and symlinks handling.
o BUG_ON in sysfs_d_iput() to check if there are any cases of mismatch
in dentry and ((struct sysfs_dirent *) dentry->d_fsdata)->s_dentry
=> changes in version 0.4
o Do not take reference to kobject while creating a dir dentry for it as it
can lead to rmmod hang or certain modules due to current limitation of
module/kobject refcounting code.
=> changes in version 0.3a
o call sysfs_close_dir_entries() when filldir() returns error in
sysfs_readdir().
=> changes in version 0.3
o corrected dentry ref counting for sysfs_remove_subdir()
=> changes in version 0.2
o sysfs_rename_dir() used to call d_move() with unhashed new_dentry causing
panic in d_move(). Added d_add() call for new_dentry before calling d_move.
o corrected error checking after sysfs_get_dentry() in
sysfs_open_dir_entries().
=> changes in version 0.1
o re-diffed for 2.6.3
=> Changes in last version
o added support for symlink
o changed logic for sysfs_remove_dir
o dir dentries now take a ref on the corresponding kobject so as to have
kobject alive during the lifetime of the dentry.
=====================================================================
o This patch provides the inode operations ->lookup(), ->readdir() and
->llseek() for sysfs directories.
o while sysfs_create_dir() we attach a sysfs_dirent structure to the d_fsdata
filed of dentry corresponding to the kobject's direcotry.
o sysfs_lookup does not hash the dentry and we hash the dentry when we have
attached the sysfs_dirent to it. This was done to cover up a race when
we attach a negative dentry and instantiate it before updating the d_fsdata
field. As after instantiating we can get a successfull lookup for the dentry
but a NULL d_fsdata field. As a result we do not create negative dentries.
o sysfs_readdir() or sysfs_dir_lseek() will bring in the dentries
corresponding to the attribute files if the offset is more than 2. These
are released when we are done with filldir().
o sysfs_d_iput() releases the ref. to the sysfs_dirent() which was taken at
the time of dentry allocation.
Signed-off-by: Andrew Morton <akpm@osdl.org>
---
25-akpm/fs/sysfs/dir.c | 351 ++++++++++++++++++++++++++++++++++++++++++-------
1 files changed, 306 insertions(+), 45 deletions(-)
diff -puN fs/sysfs/dir.c~sysfs-leaves-dir fs/sysfs/dir.c
--- 25/fs/sysfs/dir.c~sysfs-leaves-dir Fri Jun 18 14:57:20 2004
+++ 25-akpm/fs/sysfs/dir.c Fri Jun 18 14:57:20 2004
@@ -12,31 +12,181 @@
DECLARE_RWSEM(sysfs_rename_sem);
+struct inode_operations sysfs_dir_inode_operations = {
+ .lookup = sysfs_lookup,
+};
+
+struct file_operations sysfs_dir_operations = {
+ .open = sysfs_dir_open,
+ .release = sysfs_dir_close,
+ .llseek = sysfs_dir_lseek,
+ .read = generic_read_dir,
+ .readdir = sysfs_readdir,
+};
+
+static void sysfs_d_iput(struct dentry * dentry, struct inode * inode)
+{
+ struct sysfs_dirent * sd = dentry->d_fsdata;
+
+ if (sd) {
+ BUG_ON(sd->s_dentry != dentry);
+ sd->s_dentry = NULL;
+ sysfs_put(sd);
+ }
+ iput(inode);
+}
+
+static struct dentry_operations sysfs_dentry_ops = {
+ .d_iput = sysfs_d_iput,
+};
+
+const unsigned char * sysfs_get_name(struct sysfs_dirent *sd)
+{
+ struct attribute * attr;
+ struct bin_attribute * bin_attr;
+ struct sysfs_symlink * sl;
+
+ if (!sd || !sd->s_element)
+ BUG();
+
+ switch (sd->s_type) {
+ case SYSFS_KOBJECT:
+ case SYSFS_KOBJ_ATTR_GROUP:
+ /* Always have a dentry so use that */
+ return sd->s_dentry->d_name.name;
+
+ case SYSFS_KOBJ_ATTR:
+ attr = sd->s_element;
+ return attr->name;
+
+ case SYSFS_KOBJ_BIN_ATTR:
+ bin_attr = sd->s_element;
+ return bin_attr->attr.name;
+
+ case SYSFS_KOBJ_LINK:
+ sl = sd->s_element;
+ return sl->link_name;
+ }
+ return NULL;
+}
+
+static int init_file(struct inode * inode)
+{
+ inode->i_size = PAGE_SIZE;
+ inode->i_fop = &sysfs_file_operations;
+ return 0;
+}
+
static int init_dir(struct inode * inode)
{
- inode->i_op = &simple_dir_inode_operations;
- inode->i_fop = &simple_dir_operations;
+ inode->i_op = &sysfs_dir_inode_operations;
+ inode->i_fop = &sysfs_dir_operations;
/* directory inodes start off with i_nlink == 2 (for "." entry) */
inode->i_nlink++;
return 0;
}
+/* attaches attribute's sysfs_dirent to the dentry corresponding to the
+ * attribute file
+ */
+static int sysfs_attach_attr(struct sysfs_dirent * sd, struct dentry * dentry)
+{
+ struct attribute * attr = NULL;
+ struct bin_attribute * bin_attr = NULL;
+ int (* init) (struct inode *) = NULL;
+ int error = 0;
+
+ if (sd->s_type & SYSFS_KOBJ_BIN_ATTR) {
+ bin_attr = sd->s_element;
+ attr = &bin_attr->attr;
+ } else {
+ attr = sd->s_element;
+ init = init_file;
+ }
+
+ error = sysfs_create(dentry, (attr->mode & S_IALLUGO) | S_IFREG, init);
+ if (error)
+ return error;
+
+ if (bin_attr) {
+ dentry->d_inode->i_size = bin_attr->size;
+ dentry->d_inode->i_fop = &bin_fops;
+ }
+ dentry->d_op = &sysfs_dentry_ops;
+ dentry->d_fsdata = sysfs_get(sd);
+ sd->s_dentry = dentry;
+ d_rehash(dentry);
+
+ return 0;
+}
+
+static int sysfs_attach_link(struct sysfs_dirent * sd, struct dentry * dentry)
+{
+ int err = 0;
+
+ err = sysfs_create(dentry, S_IFLNK|S_IRWXUGO, init_symlink);
+ if (!err) {
+ dentry->d_op = &sysfs_dentry_ops;
+ dentry->d_fsdata = sysfs_get(sd);
+ sd->s_dentry = dentry;
+ d_rehash(dentry);
+ }
+ return err;
+}
+
+struct dentry * sysfs_lookup(struct inode *dir, struct dentry *dentry,
+ struct nameidata *nd)
+{
+ struct sysfs_dirent * parent_sd = dentry->d_parent->d_fsdata;
+ struct sysfs_dirent * sd;
+ int err = 0;
+
+ list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
+ if (sd->s_type & SYSFS_NOT_PINNED) {
+ const unsigned char * name = sysfs_get_name(sd);
+
+ if (strcmp(name, dentry->d_name.name))
+ continue;
+
+ if (sd->s_type & SYSFS_KOBJ_LINK)
+ err = sysfs_attach_link(sd, dentry);
+ else
+ err = sysfs_attach_attr(sd, dentry);
+ break;
+ }
+ }
+
+ return ERR_PTR(err);
+}
static int create_dir(struct kobject * k, struct dentry * p,
const char * n, struct dentry ** d)
{
int error;
+ umode_t mode = S_IFDIR| S_IRWXU | S_IRUGO | S_IXUGO;
down(&p->d_inode->i_sem);
*d = sysfs_get_dentry(p,n);
if (!IS_ERR(*d)) {
- error = sysfs_create(*d,
- S_IFDIR| S_IRWXU | S_IRUGO | S_IXUGO,
- init_dir);
+ error = sysfs_create(*d, mode, init_dir);
if (!error) {
- (*d)->d_fsdata = k;
- p->d_inode->i_nlink++;
+ struct sysfs_dirent * sd, * parent_sd;
+ parent_sd = p->d_fsdata;
+ sd = sysfs_new_dirent(parent_sd, k,
+ (parent_sd->s_element == k) ?
+ SYSFS_KOBJ_ATTR_GROUP :
+ SYSFS_KOBJECT);
+ if (sd) {
+ (*d)->d_fsdata = sysfs_get(sd);
+ (*d)->d_op = &sysfs_dentry_ops;
+ p->d_inode->i_nlink++;
+ sd->s_element = k;
+ sd->s_dentry = *d;
+ sd->s_mode = mode;
+ d_rehash(*d);
+ } else
+ error = -ENOMEM;
}
dput(*d);
} else
@@ -45,7 +195,6 @@ static int create_dir(struct kobject * k
return error;
}
-
int sysfs_create_subdir(struct kobject * k, const char * n, struct dentry ** d)
{
return create_dir(k,k->dentry,n,d);
@@ -79,12 +228,16 @@ int sysfs_create_dir(struct kobject * ko
return error;
}
-
static void remove_dir(struct dentry * d)
{
struct dentry * parent = dget(d->d_parent);
+ struct sysfs_dirent * sd;
+
down(&parent->d_inode->i_sem);
d_delete(d);
+ sd = d->d_fsdata;
+ list_del_init(&sd->s_sibling);
+ sysfs_put(d->d_fsdata);
if (d->d_inode)
simple_rmdir(parent->d_inode,d);
@@ -106,14 +259,14 @@ void sysfs_remove_subdir(struct dentry *
* @kobj: object.
*
* The only thing special about this is that we remove any files in
- * the directory before we remove the directory, and we've inlined
- * what used to be sysfs_rmdir() below, instead of calling separately.
+ * the directory before we remove the directory
*/
void sysfs_remove_dir(struct kobject * kobj)
{
- struct list_head * node;
struct dentry * dentry = dget(kobj->dentry);
+ struct sysfs_dirent * parent_sd = dentry->d_fsdata;
+ struct sysfs_dirent * sd, * tmp;
if (!dentry)
return;
@@ -121,38 +274,13 @@ void sysfs_remove_dir(struct kobject * k
pr_debug("sysfs %s: removing dir\n",dentry->d_name.name);
down(&dentry->d_inode->i_sem);
- spin_lock(&dcache_lock);
-restart:
- node = dentry->d_subdirs.next;
- while (node != &dentry->d_subdirs) {
- struct dentry * d = list_entry(node,struct dentry,d_child);
-
- node = node->next;
- pr_debug(" o %s (%d): ",d->d_name.name,atomic_read(&d->d_count));
- if (!d_unhashed(d) && (d->d_inode)) {
- d = dget_locked(d);
- pr_debug("removing");
-
- /**
- * Unlink and unhash.
- */
- __d_drop(d);
- spin_unlock(&dcache_lock);
- /* release the target kobject in case of
- * a symlink
- */
- if (S_ISLNK(d->d_inode->i_mode))
- kobject_put(d->d_fsdata);
-
- simple_unlink(dentry->d_inode,d);
- dput(d);
- pr_debug(" done\n");
- spin_lock(&dcache_lock);
- /* re-acquired dcache_lock, need to restart */
- goto restart;
- }
- }
- spin_unlock(&dcache_lock);
+ list_for_each_entry_safe(sd, tmp, &parent_sd->s_children, s_sibling) {
+ if (!sd->s_element)
+ continue;
+ list_del_init(&sd->s_sibling);
+ sysfs_drop_dentry(sd, dentry);
+ sysfs_put(sd);
+ }
up(&dentry->d_inode->i_sem);
remove_dir(dentry);
@@ -182,8 +310,10 @@ int sysfs_rename_dir(struct kobject * ko
if (!IS_ERR(new_dentry)) {
if (!new_dentry->d_inode) {
error = kobject_set_name(kobj,new_name);
- if (!error)
+ if (!error) {
+ d_add(new_dentry, NULL);
d_move(kobj->dentry, new_dentry);
+ }
}
dput(new_dentry);
}
@@ -193,6 +323,137 @@ int sysfs_rename_dir(struct kobject * ko
return error;
}
+int sysfs_dir_open(struct inode *inode, struct file *file)
+{
+ struct dentry * dentry = file->f_dentry;
+ struct sysfs_dirent * parent_sd = dentry->d_fsdata;
+
+ down(&dentry->d_inode->i_sem);
+ file->private_data = sysfs_new_dirent(parent_sd, NULL, 0);
+ up(&dentry->d_inode->i_sem);
+
+ return file->private_data ? 0 : -ENOMEM;
+
+}
+
+int sysfs_dir_close(struct inode *inode, struct file *file)
+{
+ struct dentry * dentry = file->f_dentry;
+ struct sysfs_dirent * cursor = file->private_data;
+
+ down(&dentry->d_inode->i_sem);
+ list_del_init(&cursor->s_sibling);
+ up(&dentry->d_inode->i_sem);
+ sysfs_put(file->private_data);
+
+ return 0;
+}
+
+/* Relationship between s_mode and the DT_xxx types */
+static inline unsigned char dt_type(struct sysfs_dirent *sd)
+{
+ return (sd->s_mode >> 12) & 15;
+}
+
+int sysfs_readdir(struct file * filp, void * dirent, filldir_t filldir)
+{
+ struct dentry *dentry = filp->f_dentry;
+ struct sysfs_dirent * parent_sd = dentry->d_fsdata;
+ struct sysfs_dirent *cursor = filp->private_data;
+ struct list_head *p, *q = &cursor->s_sibling;
+ ino_t ino;
+ int i = filp->f_pos;
+
+ switch (i) {
+ case 0:
+ ino = dentry->d_inode->i_ino;
+ if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0)
+ break;
+ filp->f_pos++;
+ i++;
+ /* fallthrough */
+ case 1:
+ ino = parent_ino(dentry);
+ if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0)
+ break;
+ filp->f_pos++;
+ i++;
+ /* fallthrough */
+ default:
+ if (filp->f_pos == 2) {
+ list_del(q);
+ list_add(q, &parent_sd->s_children);
+ }
+ for (p=q->next; p!= &parent_sd->s_children; p=p->next) {
+ struct sysfs_dirent *next;
+ const char * name;
+ int len;
+
+ next = list_entry(p, struct sysfs_dirent,
+ s_sibling);
+ if (!next->s_element)
+ continue;
+
+ name = sysfs_get_name(next);
+ len = strlen(name);
+ if (next->s_dentry)
+ ino = next->s_dentry->d_inode->i_ino;
+ else
+ ino = iunique(sysfs_sb, 2);
+
+ if (filldir(dirent, name, len, filp->f_pos, ino,
+ dt_type(next)) < 0)
+ return 0;
+
+ list_del(q);
+ list_add(q, p);
+ p = q;
+ filp->f_pos++;
+ }
+ }
+ return 0;
+}
+
+loff_t sysfs_dir_lseek(struct file * file, loff_t offset, int origin)
+{
+ struct dentry * dentry = file->f_dentry;
+
+ down(&dentry->d_inode->i_sem);
+ switch (origin) {
+ case 1:
+ offset += file->f_pos;
+ case 0:
+ if (offset >= 0)
+ break;
+ default:
+ up(&file->f_dentry->d_inode->i_sem);
+ return -EINVAL;
+ }
+ if (offset != file->f_pos) {
+ file->f_pos = offset;
+ if (file->f_pos >= 2) {
+ struct sysfs_dirent *sd = dentry->d_fsdata;
+ struct sysfs_dirent *cursor = file->private_data;
+ struct list_head *p;
+ loff_t n = file->f_pos - 2;
+
+ list_del(&cursor->s_sibling);
+ p = sd->s_children.next;
+ while (n && p != &sd->s_children) {
+ struct sysfs_dirent *next;
+ next = list_entry(p, struct sysfs_dirent,
+ s_sibling);
+ if (next->s_element)
+ n--;
+ p = p->next;
+ }
+ list_add_tail(&cursor->s_sibling, p);
+ }
+ }
+ up(&dentry->d_inode->i_sem);
+ return offset;
+}
+
EXPORT_SYMBOL(sysfs_create_dir);
EXPORT_SYMBOL(sysfs_remove_dir);
EXPORT_SYMBOL(sysfs_rename_dir);
_