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-rw-r--r--mm/shmem.c81
1 files changed, 81 insertions, 0 deletions
diff --git a/mm/shmem.c b/mm/shmem.c
index bb8ca7ef7094..b378f66cf2f9 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1362,6 +1362,7 @@ shmem_get_inode(struct super_block *sb, int mode, dev_t dev)
inode->i_mapping->a_ops = &shmem_aops;
inode->i_mapping->backing_dev_info = &shmem_backing_dev_info;
inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
+ inode->i_generation = get_seconds();
info = SHMEM_I(inode);
memset(info, 0, (char *)inode - (char *)info);
spin_lock_init(&info->lock);
@@ -1956,6 +1957,85 @@ static struct xattr_handler *shmem_xattr_handlers[] = {
};
#endif
+static struct dentry *shmem_get_parent(struct dentry *child)
+{
+ return ERR_PTR(-ESTALE);
+}
+
+static int shmem_match(struct inode *ino, void *vfh)
+{
+ __u32 *fh = vfh;
+ __u64 inum = fh[2];
+ inum = (inum << 32) | fh[1];
+ return ino->i_ino == inum && fh[0] == ino->i_generation;
+}
+
+static struct dentry *shmem_get_dentry(struct super_block *sb, void *vfh)
+{
+ struct dentry *de = NULL;
+ struct inode *inode;
+ __u32 *fh = vfh;
+ __u64 inum = fh[2];
+ inum = (inum << 32) | fh[1];
+
+ inode = ilookup5(sb, (unsigned long)(inum+fh[0]), shmem_match, vfh);
+ if (inode) {
+ de = d_find_alias(inode);
+ iput(inode);
+ }
+
+ return de? de: ERR_PTR(-ESTALE);
+}
+
+static struct dentry *shmem_decode_fh(struct super_block *sb, __u32 *fh,
+ int len, int type,
+ int (*acceptable)(void *context, struct dentry *de),
+ void *context)
+{
+ if (len < 3)
+ return ERR_PTR(-ESTALE);
+
+ return sb->s_export_op->find_exported_dentry(sb, fh, NULL, acceptable,
+ context);
+}
+
+static int shmem_encode_fh(struct dentry *dentry, __u32 *fh, int *len,
+ int connectable)
+{
+ struct inode *inode = dentry->d_inode;
+
+ if (*len < 3)
+ return 255;
+
+ if (hlist_unhashed(&inode->i_hash)) {
+ /* Unfortunately insert_inode_hash is not idempotent,
+ * so as we hash inodes here rather than at creation
+ * time, we need a lock to ensure we only try
+ * to do it once
+ */
+ static DEFINE_SPINLOCK(lock);
+ spin_lock(&lock);
+ if (hlist_unhashed(&inode->i_hash))
+ __insert_inode_hash(inode,
+ inode->i_ino + inode->i_generation);
+ spin_unlock(&lock);
+ }
+
+ fh[0] = inode->i_generation;
+ fh[1] = inode->i_ino;
+ fh[2] = ((__u64)inode->i_ino) >> 32;
+
+ *len = 3;
+ return 1;
+}
+
+static struct export_operations shmem_export_ops = {
+ .get_parent = shmem_get_parent,
+ .get_dentry = shmem_get_dentry,
+ .encode_fh = shmem_encode_fh,
+ .decode_fh = shmem_decode_fh,
+};
+
static int shmem_parse_options(char *options, int *mode, uid_t *uid,
gid_t *gid, unsigned long *blocks, unsigned long *inodes,
int *policy, nodemask_t *policy_nodes)
@@ -2128,6 +2208,7 @@ static int shmem_fill_super(struct super_block *sb,
&inodes, &policy, &policy_nodes))
return -EINVAL;
}
+ sb->s_export_op = &shmem_export_ops;
#else
sb->s_flags |= MS_NOUSER;
#endif