Ocfs2: Add new OCFS2_IOC_INFO ioctl for ocfs2 v8.

The reason why we need this ioctl is to offer the none-privileged
end-user a possibility to get filesys info gathering.

We use OCFS2_IOC_INFO to manipulate the new ioctl, userspace passes a
structure to kernel containing an array of request pointers and request
count, such as,

* From userspace:

struct ocfs2_info_blocksize oib = {
        .ib_req = {
                .ir_magic = OCFS2_INFO_MAGIC,
                .ir_code = OCFS2_INFO_BLOCKSIZE,
                ...
        }
        ...
}

struct ocfs2_info_clustersize oic = {
        ...
}

uint64_t reqs[2] = {(unsigned long)&oib,
                    (unsigned long)&oic};

struct ocfs2_info info = {
        .oi_requests = reqs,
        .oi_count = 2,
}

ret = ioctl(fd, OCFS2_IOC_INFO, &info);

* In kernel:

Get the request pointers from *info*, then handle each request one bye one.

Idea here is to make the spearated request small enough to guarantee
a better backward&forward compatibility since a small piece of request
would be less likely to be broken if filesys on raw disk get changed.

Currently, the following 7 requests are supported per the requirement from
userspace tool o2info, and I believe it will grow over time:-)

        OCFS2_INFO_CLUSTERSIZE
        OCFS2_INFO_BLOCKSIZE
        OCFS2_INFO_MAXSLOTS
        OCFS2_INFO_LABEL
        OCFS2_INFO_UUID
        OCFS2_INFO_FS_FEATURES
        OCFS2_INFO_JOURNAL_SIZE

This ioctl is only specific to OCFS2.

Signed-off-by: Tristan Ye <tristan.ye@oracle.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>

1 files changed, 356 insertions, 0 deletions

diff --git a/fs/ocfs2/ioctl.c b/fs/ocfs2/ioctl.c
index 7d9d9c132cef..7a4868196152 100644
--- a/fs/ocfs2/ioctl.c
+++ b/fs/ocfs2/ioctl.c
@@ -26,6 +26,26 @@
 
 #include <linux/ext2_fs.h>
 
+#define o2info_from_user(a, b)  \
+                copy_from_user(&(a), (b), sizeof(a))
+#define o2info_to_user(a, b)    \
+                copy_to_user((typeof(a) __user *)b, &(a), sizeof(a))
+
+/*
+ * This call is void because we are already reporting an error that may
+ * be -EFAULT.  The error will be returned from the ioctl(2) call.  It's
+ * just a best-effort to tell userspace that this request caused the error.
+ */
+static inline void __o2info_set_request_error(struct ocfs2_info_request *kreq,
+                                        struct ocfs2_info_request __user *req)
+{
+        kreq->ir_flags |= OCFS2_INFO_FL_ERROR;
+        (void)put_user(kreq->ir_flags, (__u32 __user *)&(req->ir_flags));
+}
+
+#define o2info_set_request_error(a, b) \
+                __o2info_set_request_error((struct ocfs2_info_request *)&(a), b)
+
 static int ocfs2_get_inode_attr(struct inode *inode, unsigned *flags)
 {
         int status;
@@ -109,6 +129,328 @@ bail:
         return status;
 }
 
+int ocfs2_info_handle_blocksize(struct inode *inode,
+                                struct ocfs2_info_request __user *req)
+{
+        int status = -EFAULT;
+        struct ocfs2_info_blocksize oib;
+
+        if (o2info_from_user(oib, req))
+                goto bail;
+
+        oib.ib_blocksize = inode->i_sb->s_blocksize;
+        oib.ib_req.ir_flags |= OCFS2_INFO_FL_FILLED;
+
+        if (o2info_to_user(oib, req))
+                goto bail;
+
+        status = 0;
+bail:
+        if (status)
+                o2info_set_request_error(oib, req);
+
+        return status;
+}
+
+int ocfs2_info_handle_clustersize(struct inode *inode,
+                                  struct ocfs2_info_request __user *req)
+{
+        int status = -EFAULT;
+        struct ocfs2_info_clustersize oic;
+        struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
+
+        if (o2info_from_user(oic, req))
+                goto bail;
+
+        oic.ic_clustersize = osb->s_clustersize;
+        oic.ic_req.ir_flags |= OCFS2_INFO_FL_FILLED;
+
+        if (o2info_to_user(oic, req))
+                goto bail;
+
+        status = 0;
+bail:
+        if (status)
+                o2info_set_request_error(oic, req);
+
+        return status;
+}
+
+int ocfs2_info_handle_maxslots(struct inode *inode,
+                               struct ocfs2_info_request __user *req)
+{
+        int status = -EFAULT;
+        struct ocfs2_info_maxslots oim;
+        struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
+
+        if (o2info_from_user(oim, req))
+                goto bail;
+
+        oim.im_max_slots = osb->max_slots;
+        oim.im_req.ir_flags |= OCFS2_INFO_FL_FILLED;
+
+        if (o2info_to_user(oim, req))
+                goto bail;
+
+        status = 0;
+bail:
+        if (status)
+                o2info_set_request_error(oim, req);
+
+        return status;
+}
+
+int ocfs2_info_handle_label(struct inode *inode,
+                            struct ocfs2_info_request __user *req)
+{
+        int status = -EFAULT;
+        struct ocfs2_info_label oil;
+        struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
+
+        if (o2info_from_user(oil, req))
+                goto bail;
+
+        memcpy(oil.il_label, osb->vol_label, OCFS2_MAX_VOL_LABEL_LEN);
+        oil.il_req.ir_flags |= OCFS2_INFO_FL_FILLED;
+
+        if (o2info_to_user(oil, req))
+                goto bail;
+
+        status = 0;
+bail:
+        if (status)
+                o2info_set_request_error(oil, req);
+
+        return status;
+}
+
+int ocfs2_info_handle_uuid(struct inode *inode,
+                           struct ocfs2_info_request __user *req)
+{
+        int status = -EFAULT;
+        struct ocfs2_info_uuid oiu;
+        struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
+
+        if (o2info_from_user(oiu, req))
+                goto bail;
+
+        memcpy(oiu.iu_uuid_str, osb->uuid_str, OCFS2_TEXT_UUID_LEN + 1);
+        oiu.iu_req.ir_flags |= OCFS2_INFO_FL_FILLED;
+
+        if (o2info_to_user(oiu, req))
+                goto bail;
+
+        status = 0;
+bail:
+        if (status)
+                o2info_set_request_error(oiu, req);
+
+        return status;
+}
+
+int ocfs2_info_handle_fs_features(struct inode *inode,
+                                  struct ocfs2_info_request __user *req)
+{
+        int status = -EFAULT;
+        struct ocfs2_info_fs_features oif;
+        struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
+
+        if (o2info_from_user(oif, req))
+                goto bail;
+
+        oif.if_compat_features = osb->s_feature_compat;
+        oif.if_incompat_features = osb->s_feature_incompat;
+        oif.if_ro_compat_features = osb->s_feature_ro_compat;
+        oif.if_req.ir_flags |= OCFS2_INFO_FL_FILLED;
+
+        if (o2info_to_user(oif, req))
+                goto bail;
+
+        status = 0;
+bail:
+        if (status)
+                o2info_set_request_error(oif, req);
+
+        return status;
+}
+
+int ocfs2_info_handle_journal_size(struct inode *inode,
+                                   struct ocfs2_info_request __user *req)
+{
+        int status = -EFAULT;
+        struct ocfs2_info_journal_size oij;
+        struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
+
+        if (o2info_from_user(oij, req))
+                goto bail;
+
+        oij.ij_journal_size = osb->journal->j_inode->i_size;
+
+        oij.ij_req.ir_flags |= OCFS2_INFO_FL_FILLED;
+
+        if (o2info_to_user(oij, req))
+                goto bail;
+
+        status = 0;
+bail:
+        if (status)
+                o2info_set_request_error(oij, req);
+
+        return status;
+}
+
+int ocfs2_info_handle_unknown(struct inode *inode,
+                              struct ocfs2_info_request __user *req)
+{
+        int status = -EFAULT;
+        struct ocfs2_info_request oir;
+
+        if (o2info_from_user(oir, req))
+                goto bail;
+
+        oir.ir_flags &= ~OCFS2_INFO_FL_FILLED;
+
+        if (o2info_to_user(oir, req))
+                goto bail;
+
+        status = 0;
+bail:
+        if (status)
+                o2info_set_request_error(oir, req);
+
+        return status;
+}
+
+/*
+ * Validate and distinguish OCFS2_IOC_INFO requests.
+ *
+ * - validate the magic number.
+ * - distinguish different requests.
+ * - validate size of different requests.
+ */
+int ocfs2_info_handle_request(struct inode *inode,
+                              struct ocfs2_info_request __user *req)
+{
+        int status = -EFAULT;
+        struct ocfs2_info_request oir;
+
+        if (o2info_from_user(oir, req))
+                goto bail;
+
+        status = -EINVAL;
+        if (oir.ir_magic != OCFS2_INFO_MAGIC)
+                goto bail;
+
+        switch (oir.ir_code) {
+        case OCFS2_INFO_BLOCKSIZE:
+                if (oir.ir_size == sizeof(struct ocfs2_info_blocksize))
+                        status = ocfs2_info_handle_blocksize(inode, req);
+                break;
+        case OCFS2_INFO_CLUSTERSIZE:
+                if (oir.ir_size == sizeof(struct ocfs2_info_clustersize))
+                        status = ocfs2_info_handle_clustersize(inode, req);
+                break;
+        case OCFS2_INFO_MAXSLOTS:
+                if (oir.ir_size == sizeof(struct ocfs2_info_maxslots))
+                        status = ocfs2_info_handle_maxslots(inode, req);
+                break;
+        case OCFS2_INFO_LABEL:
+                if (oir.ir_size == sizeof(struct ocfs2_info_label))
+                        status = ocfs2_info_handle_label(inode, req);
+                break;
+        case OCFS2_INFO_UUID:
+                if (oir.ir_size == sizeof(struct ocfs2_info_uuid))
+                        status = ocfs2_info_handle_uuid(inode, req);
+                break;
+        case OCFS2_INFO_FS_FEATURES:
+                if (oir.ir_size == sizeof(struct ocfs2_info_fs_features))
+                        status = ocfs2_info_handle_fs_features(inode, req);
+                break;
+        case OCFS2_INFO_JOURNAL_SIZE:
+                if (oir.ir_size == sizeof(struct ocfs2_info_journal_size))
+                        status = ocfs2_info_handle_journal_size(inode, req);
+                break;
+        default:
+                status = ocfs2_info_handle_unknown(inode, req);
+                break;
+        }
+
+bail:
+        return status;
+}
+
+int ocfs2_get_request_ptr(struct ocfs2_info *info, int idx,
+                          u64 *req_addr, int compat_flag)
+{
+        int status = -EFAULT;
+        u64 __user *bp = NULL;
+
+        if (compat_flag) {
+#ifdef CONFIG_COMPAT
+                /*
+                 * pointer bp stores the base address of a pointers array,
+                 * which collects all addresses of separate request.
+                 */
+                bp = (u64 __user *)(unsigned long)compat_ptr(info->oi_requests);
+#else
+                BUG();
+#endif
+        } else
+                bp = (u64 __user *)(unsigned long)(info->oi_requests);
+
+        if (o2info_from_user(*req_addr, bp + idx))
+                goto bail;
+
+        status = 0;
+bail:
+        return status;
+}
+
+/*
+ * OCFS2_IOC_INFO handles an array of requests passed from userspace.
+ *
+ * ocfs2_info_handle() recevies a large info aggregation, grab and
+ * validate the request count from header, then break it into small
+ * pieces, later specific handlers can handle them one by one.
+ *
+ * Idea here is to make each separate request small enough to ensure
+ * a better backward&forward compatibility, since a small piece of
+ * request will be less likely to be broken if disk layout get changed.
+ */
+int ocfs2_info_handle(struct inode *inode, struct ocfs2_info *info,
+                      int compat_flag)
+{
+        int i, status = 0;
+        u64 req_addr;
+        struct ocfs2_info_request __user *reqp;
+
+        if ((info->oi_count > OCFS2_INFO_MAX_REQUEST) ||
+            (!info->oi_requests)) {
+                status = -EINVAL;
+                goto bail;
+        }
+
+        for (i = 0; i < info->oi_count; i++) {
+
+                status = ocfs2_get_request_ptr(info, i, &req_addr, compat_flag);
+                if (status)
+                        break;
+
+                reqp = (struct ocfs2_info_request *)(unsigned long)req_addr;
+                if (!reqp) {
+                        status = -EINVAL;
+                        goto bail;
+                }
+
+                status = ocfs2_info_handle_request(inode, reqp);
+                if (status)
+                        break;
+        }
+
+bail:
+        return status;
+}
+
 long ocfs2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 {
         struct inode *inode = filp->f_path.dentry->d_inode;
@@ -120,6 +462,7 @@ long ocfs2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
         struct reflink_arguments args;
         const char *old_path, *new_path;
         bool preserve;
+        struct ocfs2_info info;
 
         switch (cmd) {
         case OCFS2_IOC_GETFLAGS:
@@ -174,6 +517,12 @@ long ocfs2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
                 preserve = (args.preserve != 0);
 
                 return ocfs2_reflink_ioctl(inode, old_path, new_path, preserve);
+        case OCFS2_IOC_INFO:
+                if (copy_from_user(&info, (struct ocfs2_info __user *)arg,
+                                   sizeof(struct ocfs2_info)))
+                        return -EFAULT;
+
+                return ocfs2_info_handle(inode, &info, 0);
         default:
                 return -ENOTTY;
         }
@@ -185,6 +534,7 @@ long ocfs2_compat_ioctl(struct file *file, unsigned cmd, unsigned long arg)
         bool preserve;
         struct reflink_arguments args;
         struct inode *inode = file->f_path.dentry->d_inode;
+        struct ocfs2_info info;
 
         switch (cmd) {
         case OCFS2_IOC32_GETFLAGS:
@@ -209,6 +559,12 @@ long ocfs2_compat_ioctl(struct file *file, unsigned cmd, unsigned long arg)
 
                 return ocfs2_reflink_ioctl(inode, compat_ptr(args.old_path),
                                            compat_ptr(args.new_path), preserve);
+        case OCFS2_IOC_INFO:
+                if (copy_from_user(&info, (struct ocfs2_info __user *)arg,
+                                   sizeof(struct ocfs2_info)))
+                        return -EFAULT;
+
+                return ocfs2_info_handle(inode, &info, 1);
         default:
                 return -ENOIOCTLCMD;
         }