LU-3613 llite: Add ioctl to get parent fids from link EA.

[fs/lustre-release.git] / lustre / llite / llite_lib.c

diff --git a/lustre/llite/llite_lib.c b/lustre/llite/llite_lib.c
index dc62d60..17e388f 100644 (file)
--- a/lustre/llite/llite_lib.c
+++ b/lustre/llite/llite_lib.c
@@ -2777,3 +2777,131 @@ void ll_compute_rootsquash_state(struct ll_sb_info *sbi)
        }
        up_write(&squash->rsi_sem);
 }
+
+/**
+ * Parse linkea content to extract information about a given hardlink
+ *
+ * \param[in]  ldata  - Initialized linkea data
+ * \param[in]  linkno - Link identifier
+ * \param[out] gpout  - Destination structure to fill with linkno,
+ *                      parent FID and entry name
+ * \param[in]  size   - Size of the gp_name buffer in gpout
+ *
+ * \retval 0 on success
+ * \retval Appropriate negative error code on failure
+ */
+static int ll_linkea_decode(struct linkea_data *ldata, unsigned int linkno,
+                           struct getparent *gpout, size_t name_size)
+{
+       unsigned int    idx;
+       struct lu_name  ln;
+       int             rc;
+       ENTRY;
+
+       rc = linkea_init(ldata);
+       if (rc < 0)
+               RETURN(rc);
+
+       if (linkno >= ldata->ld_leh->leh_reccount)
+               /* beyond last link */
+               RETURN(-ENODATA);
+
+       linkea_first_entry(ldata);
+       idx = 0;
+       while (ldata->ld_lee != NULL) {
+               linkea_entry_unpack(ldata->ld_lee, &ldata->ld_reclen, &ln,
+                                   &gpout->gp_fid);
+               if (idx == linkno)
+                       break;
+
+               linkea_next_entry(ldata);
+               idx++;
+       }
+
+       if (idx < linkno)
+               RETURN(-ENODATA);
+
+       if (ln.ln_namelen >= name_size)
+               RETURN(-EOVERFLOW);
+
+       gpout->gp_linkno = linkno;
+       strlcpy(gpout->gp_name, ln.ln_name, name_size);
+       RETURN(0);
+}
+
+/**
+ * Get parent FID and name of an identified link. Operation is performed for
+ * a given link number, letting the caller iterate over linkno to list one or
+ * all links of an entry.
+ *
+ * \param[in]     file - File descriptor against which to perform the operation
+ * \param[in,out] arg  - User-filled structure containing the linkno to operate
+ *                       on and the available size. It is eventually filled with
+ *                       the requested information or left untouched on error
+ *
+ * \retval - 0 on success
+ * \retval - Appropriate negative error code on failure
+ */
+int ll_getparent(struct file *file, struct getparent __user *arg)
+{
+       struct dentry           *dentry = file->f_dentry;
+       struct inode            *inode = file->f_dentry->d_inode;
+       struct linkea_data      *ldata;
+       struct lu_buf            buf = LU_BUF_NULL;
+       struct getparent        *gpout;
+       __u32                    linkno;
+       __u32                    name_size;
+       size_t                   out_size;
+       int                      rc;
+
+       ENTRY;
+
+       if (!cfs_capable(CFS_CAP_DAC_READ_SEARCH) &&
+           !(ll_i2sbi(inode)->ll_flags & LL_SBI_USER_FID2PATH))
+               RETURN(-EPERM);
+
+       if (get_user(name_size, &arg->gp_name_size))
+               RETURN(-EFAULT);
+
+       if (get_user(linkno, &arg->gp_linkno))
+               RETURN(-EFAULT);
+
+       if (name_size > PATH_MAX)
+               RETURN(-EINVAL);
+
+       OBD_ALLOC(ldata, sizeof(*ldata));
+       if (ldata == NULL)
+               RETURN(-ENOMEM);
+
+       rc = linkea_data_new(ldata, &buf);
+       if (rc < 0)
+               GOTO(ldata_free, rc);
+
+       out_size = sizeof(*gpout) + name_size;
+       OBD_ALLOC(gpout, out_size);
+       if (gpout == NULL)
+               GOTO(lb_free, rc = -ENOMEM);
+
+       if (copy_from_user(gpout, arg, sizeof(*gpout)))
+               GOTO(gp_free, rc = -EFAULT);
+
+       rc = ll_getxattr(dentry, XATTR_NAME_LINK, buf.lb_buf, buf.lb_len);
+       if (rc < 0)
+               GOTO(gp_free, rc);
+
+       rc = ll_linkea_decode(ldata, linkno, gpout, name_size);
+       if (rc < 0)
+               GOTO(gp_free, rc);
+
+       if (copy_to_user(arg, gpout, out_size))
+               GOTO(gp_free, rc = -EFAULT);
+
+gp_free:
+       OBD_FREE(gpout, out_size);
+lb_free:
+       lu_buf_free(&buf);
+ldata_free:
+       OBD_FREE(ldata, sizeof(*ldata));
+
+       RETURN(rc);
+}