The patch titled
sysfs: add sysfs_dirent->s_parent
has been added to the -mm tree. Its filename is
sysfs-add-sysfs_dirent-s_parent.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: sysfs: add sysfs_dirent->s_parent
From: Tejun Heo <htejun@xxxxxxxxx>
Add sysfs_dirent->s_parent. With this patch, each sd points to and holds a
reference to its parent. This allows walking sysfs tree without referencing
sd->s_dentry which can go away anytime if the user doesn't control when it's
deleted.
sd->s_parent is initialized and parent is referenced in sysfs_attach_dirent().
Reference to parent is released when the sd is released, so as long as
reference to a sd is held, s_parent can be followed.
dentry walk in sysfs_readdir() is convereted to s_parent walk.
This will be used to reimplement symlink such that it uses only sysfs_dirent
tree.
Signed-off-by: Tejun Heo <htejun@xxxxxxxxx>
Cc: Cornelia Huck <cornelia.huck@xxxxxxxxxx>
Cc: Dipankar Sarma <dipankar@xxxxxxxxxx>
Cc: Maneesh Soni <maneesh@xxxxxxxxxx>
Cc: Greg KH <greg@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/sysfs/dir.c | 27 ++++++++++++++++++++-------
fs/sysfs/mount.c | 1 +
fs/sysfs/sysfs.h | 1 +
3 files changed, 22 insertions(+), 7 deletions(-)
diff -puN fs/sysfs/dir.c~sysfs-add-sysfs_dirent-s_parent fs/sysfs/dir.c
--- a/fs/sysfs/dir.c~sysfs-add-sysfs_dirent-s_parent
+++ a/fs/sysfs/dir.c
@@ -16,6 +16,11 @@ DECLARE_RWSEM(sysfs_rename_sem);
void release_sysfs_dirent(struct sysfs_dirent * sd)
{
+ struct sysfs_dirent *parent_sd;
+
+ repeat:
+ parent_sd = sd->s_parent;
+
if (sd->s_type & SYSFS_KOBJ_LINK) {
struct sysfs_symlink * sl = sd->s_element;
kfree(sl->link_name);
@@ -24,6 +29,10 @@ void release_sysfs_dirent(struct sysfs_d
}
kfree(sd->s_iattr);
kmem_cache_free(sysfs_dir_cachep, sd);
+
+ sd = parent_sd;
+ if (sd && atomic_dec_and_test(&sd->s_count))
+ goto repeat;
}
static void sysfs_d_iput(struct dentry * dentry, struct inode * inode)
@@ -71,8 +80,10 @@ void sysfs_attach_dirent(struct sysfs_di
dentry->d_op = &sysfs_dentry_ops;
}
- if (parent_sd)
+ if (parent_sd) {
+ sd->s_parent = sysfs_get(parent_sd);
list_add(&sd->s_sibling, &parent_sd->s_children);
+ }
}
/*
@@ -508,7 +519,7 @@ static int sysfs_readdir(struct file * f
i++;
/* fallthrough */
case 1:
- ino = (unsigned long)dentry->d_parent->d_fsdata;
+ ino = (unsigned long)parent_sd->s_parent;
if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0)
break;
filp->f_pos++;
@@ -625,13 +636,13 @@ int sysfs_make_shadowed_dir(struct kobje
struct dentry *sysfs_create_shadow_dir(struct kobject *kobj)
{
+ struct dentry *dir = kobj->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 *sd;
- struct dentry *parent, *dir, *shadow;
- struct inode *inode;
- dir = kobj->dentry;
- inode = dir->d_inode;
- parent = dir->d_parent;
shadow = ERR_PTR(-EINVAL);
if (!sysfs_is_shadowed_inode(inode))
goto out;
@@ -643,6 +654,8 @@ struct dentry *sysfs_create_shadow_dir(s
sd = sysfs_new_dirent(kobj, inode->i_mode, SYSFS_DIR);
if (!sd)
goto nomem;
+ /* point to parent_sd but don't attach to it */
+ sd->s_parent = sysfs_get(parent_sd);
sysfs_attach_dirent(sd, NULL, shadow);
d_instantiate(shadow, igrab(inode));
diff -puN fs/sysfs/mount.c~sysfs-add-sysfs_dirent-s_parent fs/sysfs/mount.c
--- a/fs/sysfs/mount.c~sysfs-add-sysfs_dirent-s_parent
+++ a/fs/sysfs/mount.c
@@ -28,6 +28,7 @@ static const struct super_operations sys
};
static struct sysfs_dirent sysfs_root = {
+ .s_count = ATOMIC_INIT(1),
.s_sibling = LIST_HEAD_INIT(sysfs_root.s_sibling),
.s_children = LIST_HEAD_INIT(sysfs_root.s_children),
.s_element = NULL,
diff -puN fs/sysfs/sysfs.h~sysfs-add-sysfs_dirent-s_parent fs/sysfs/sysfs.h
--- a/fs/sysfs/sysfs.h~sysfs-add-sysfs_dirent-s_parent
+++ a/fs/sysfs/sysfs.h
@@ -1,5 +1,6 @@
struct sysfs_dirent {
atomic_t s_count;
+ struct sysfs_dirent * s_parent;
struct list_head s_sibling;
struct list_head s_children;
void * s_element;
_
Patches currently in -mm which might be from htejun@xxxxxxxxx are
origin.patch
revert-gregkh-driver-sysfs-crash-debugging.patch
sysfs-fix-i_ino-handling-in-sysfs.patch
sysfs-fix-error-handling-in-binattr-write.patch
sysfs-move-release_sysfs_dirent-to-dirc.patch
sysfs-flatten-cleanup-paths-in-sysfs_add_link-and-create_dir.patch
sysfs-consolidate-sysfs_dirent-creation-functions.patch
sysfs-add-sysfs_dirent-s_parent.patch
sysfs-add-sysfs_dirent-s_name.patch
sysfs-make-sysfs_dirent-s_element-a-union.patch
sysfs-implement-kobj_sysfs_assoc_lock.patch
sysfs-reimplement-symlink-using-sysfs_dirent-tree.patch
sysfs-implement-bin_buffer.patch
sysfs-implement-sysfs_dirent-active-reference-and-immediate-disconnect.patch
sysfs-kill-attribute-file-orphaning.patch
sysfs-kill-unnecessary-attribute-owner.patch
sysfs-kill-unnecessary-attribute-owner-fix.patch
git-libata-all.patch
sata_nv-add-back-some-verbosity-into-adma-error_handler.patch
optional-led-trigger-for-libata.patch
drivers-ata-pata_cmd640c-fix-build-with-config_pm=n.patch
git-scsi-misc.patch
introduce-config_has_dma.patch
-
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