[PATCH] sysfs-iattr: add sysfs_setattr

o This adds ->i_op->setattr VFS method for sysfs inodes. The changed
  attribues are saved in the persistent sysfs_dirent structure as a pointer
  to struct iattr. The struct iattr is allocated only for those sysfs_dirent's
  for which default attributes are getting changed. Thanks to Jon Smirl for
  this suggestion.

Signed-off-by: Maneesh Soni <maneesh@in.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 65 insertions, 0 deletions

diff --git a/fs/sysfs/inode.c b/fs/sysfs/inode.c
index aff7b2dfa8ee..400c90be5685 100644
--- a/fs/sysfs/inode.c
+++ b/fs/sysfs/inode.c
@@ -26,6 +26,71 @@ static struct backing_dev_info sysfs_backing_dev_info = {
         .capabilities   = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK,
 };
 
+static struct inode_operations sysfs_inode_operations ={
+        .setattr        = sysfs_setattr,
+};
+
+int sysfs_setattr(struct dentry * dentry, struct iattr * iattr)
+{
+        struct inode * inode = dentry->d_inode;
+        struct sysfs_dirent * sd = dentry->d_fsdata;
+        struct iattr * sd_iattr;
+        unsigned int ia_valid = iattr->ia_valid;
+        int error;
+
+        if (!sd)
+                return -EINVAL;
+
+        sd_iattr = sd->s_iattr;
+
+        error = inode_change_ok(inode, iattr);
+        if (error)
+                return error;
+
+        error = inode_setattr(inode, iattr);
+        if (error)
+                return error;
+
+        if (!sd_iattr) {
+                /* setting attributes for the first time, allocate now */
+                sd_iattr = kmalloc(sizeof(struct iattr), GFP_KERNEL);
+                if (!sd_iattr)
+                        return -ENOMEM;
+                /* assign default attributes */
+                memset(sd_iattr, 0, sizeof(struct iattr));
+                sd_iattr->ia_mode = sd->s_mode;
+                sd_iattr->ia_uid = 0;
+                sd_iattr->ia_gid = 0;
+                sd_iattr->ia_atime = sd_iattr->ia_mtime = sd_iattr->ia_ctime = CURRENT_TIME;
+                sd->s_iattr = sd_iattr;
+        }
+
+        /* attributes were changed atleast once in past */
+
+        if (ia_valid & ATTR_UID)
+                sd_iattr->ia_uid = iattr->ia_uid;
+        if (ia_valid & ATTR_GID)
+                sd_iattr->ia_gid = iattr->ia_gid;
+        if (ia_valid & ATTR_ATIME)
+                sd_iattr->ia_atime = timespec_trunc(iattr->ia_atime,
+                                                inode->i_sb->s_time_gran);
+        if (ia_valid & ATTR_MTIME)
+                sd_iattr->ia_mtime = timespec_trunc(iattr->ia_mtime,
+                                                inode->i_sb->s_time_gran);
+        if (ia_valid & ATTR_CTIME)
+                sd_iattr->ia_ctime = timespec_trunc(iattr->ia_ctime,
+                                                inode->i_sb->s_time_gran);
+        if (ia_valid & ATTR_MODE) {
+                umode_t mode = iattr->ia_mode;
+
+                if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
+                        mode &= ~S_ISGID;
+                sd_iattr->ia_mode = mode;
+        }
+
+        return error;
+}
+
 struct inode * sysfs_new_inode(mode_t mode)
 {
         struct inode * inode = new_inode(sysfs_sb);