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Subject[PATCH 15/26] sysfs: Implement sysfs_getattr & sysfs_permission
From: Eric W. Biederman <ebiederm@xmission.com>

With the implementation of sysfs_getattr and sysfs_permission
sysfs becomes able to lazily propogate inode attribute changes
from the sysfs_dirents to the vfs inodes. This paves the way
for deleting significant chunks of now unnecessary code.

Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Eric W. Biederman <ebiederm@aristanetworks.com>
---
fs/sysfs/dir.c | 2 +
fs/sysfs/inode.c | 54 ++++++++++++++++++++++++++++++++++++++++-----------
fs/sysfs/symlink.c | 3 ++
fs/sysfs/sysfs.h | 2 +
4 files changed, 49 insertions(+), 12 deletions(-)

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index c6472d8..b75c938 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -763,6 +763,8 @@ static struct dentry * sysfs_lookup(struct inode *dir, struct dentry *dentry,
const struct inode_operations sysfs_dir_inode_operations = {
.lookup = sysfs_lookup,
.setattr = sysfs_setattr,
+ .getattr = sysfs_getattr,
+ .permission = sysfs_permission,
};

static void remove_dir(struct sysfs_dirent *dir_sd)
diff --git a/fs/sysfs/inode.c b/fs/sysfs/inode.c
index dd154cb..1b7ed3c 100644
--- a/fs/sysfs/inode.c
+++ b/fs/sysfs/inode.c
@@ -35,6 +35,8 @@ static struct backing_dev_info sysfs_backing_dev_info = {

static const struct inode_operations sysfs_inode_operations ={
.setattr = sysfs_setattr,
+ .getattr = sysfs_getattr,
+ .permission = sysfs_permission,
};

int __init sysfs_inode_init(void)
@@ -123,7 +125,6 @@ static inline void set_default_inode_attr(struct inode * inode, mode_t mode)

static inline void set_inode_attr(struct inode * inode, struct iattr * iattr)
{
- inode->i_mode = iattr->ia_mode;
inode->i_uid = iattr->ia_uid;
inode->i_gid = iattr->ia_gid;
inode->i_atime = iattr->ia_atime;
@@ -154,6 +155,33 @@ static int sysfs_count_nlink(struct sysfs_dirent *sd)
return nr + 2;
}

+static void sysfs_refresh_inode(struct sysfs_dirent *sd, struct inode *inode)
+{
+ inode->i_mode = sd->s_mode;
+ if (sd->s_iattr) {
+ /* sysfs_dirent has non-default attributes
+ * get them from persistent copy in sysfs_dirent
+ */
+ set_inode_attr(inode, sd->s_iattr);
+ }
+
+ if (sysfs_type(sd) == SYSFS_DIR)
+ inode->i_nlink = sysfs_count_nlink(sd);
+}
+
+int sysfs_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
+{
+ struct sysfs_dirent *sd = dentry->d_fsdata;
+ struct inode *inode = dentry->d_inode;
+
+ mutex_lock(&sysfs_mutex);
+ sysfs_refresh_inode(sd, inode);
+ mutex_unlock(&sysfs_mutex);
+
+ generic_fillattr(inode, stat);
+ return 0;
+}
+
static void sysfs_init_inode(struct sysfs_dirent *sd, struct inode *inode)
{
struct bin_attribute *bin_attr;
@@ -162,25 +190,16 @@ static void sysfs_init_inode(struct sysfs_dirent *sd, struct inode *inode)
inode->i_mapping->a_ops = &sysfs_aops;
inode->i_mapping->backing_dev_info = &sysfs_backing_dev_info;
inode->i_op = &sysfs_inode_operations;
- inode->i_ino = sd->s_ino;
lockdep_set_class(&inode->i_mutex, &sysfs_inode_imutex_key);

- if (sd->s_iattr) {
- /* sysfs_dirent has non-default attributes
- * get them for the new inode from persistent copy
- * in sysfs_dirent
- */
- set_inode_attr(inode, sd->s_iattr);
- } else
- set_default_inode_attr(inode, sd->s_mode);
-
+ set_default_inode_attr(inode, sd->s_mode);
+ sysfs_refresh_inode(sd, inode);

/* 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;
@@ -263,3 +282,14 @@ int sysfs_hash_and_remove(struct sysfs_dirent *dir_sd, const char *name)
else
return -ENOENT;
}
+
+int sysfs_permission(struct inode *inode, int mask)
+{
+ struct sysfs_dirent *sd = inode->i_private;
+
+ mutex_lock(&sysfs_mutex);
+ sysfs_refresh_inode(sd, inode);
+ mutex_unlock(&sysfs_mutex);
+
+ return generic_permission(inode, mask, NULL);
+}
diff --git a/fs/sysfs/symlink.c b/fs/sysfs/symlink.c
index 0367ed1..05e4984 100644
--- a/fs/sysfs/symlink.c
+++ b/fs/sysfs/symlink.c
@@ -201,6 +201,9 @@ const struct inode_operations sysfs_symlink_inode_operations = {
.readlink = generic_readlink,
.follow_link = sysfs_follow_link,
.put_link = sysfs_put_link,
+ .setattr = sysfs_setattr,
+ .getattr = sysfs_getattr,
+ .permission = sysfs_permission,
};


diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index 043bb13..f5b53cf 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -148,6 +148,8 @@ struct inode *sysfs_get_inode(struct sysfs_dirent *sd);
void sysfs_delete_inode(struct inode *inode);
int sysfs_sd_setattr(struct sysfs_dirent *sd, struct iattr *iattr);
int sysfs_setattr(struct dentry *dentry, struct iattr *iattr);
+int sysfs_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat);
+int sysfs_permission(struct inode *inode, int mask);
int sysfs_hash_and_remove(struct sysfs_dirent *dir_sd, const char *name);
int sysfs_inode_init(void);

--
1.6.3.1.54.g99dd.dirty


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