LU-16025 llite: adjust read count as file got truncated

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

diff --git a/lustre/llite/file.c b/lustre/llite/file.c
index 5842e9f..86e55f4 100644 (file)
--- a/lustre/llite/file.c
+++ b/lustre/llite/file.c
@@ -1939,6 +1939,59 @@ ll_do_fast_read(struct kiocb *iocb, struct iov_iter *iter)
        return result;
 }
 
+/**
+ * Confine read iter lest read beyond the EOF
+ *
+ * \param iocb [in]    kernel iocb
+ * \param to [in]      reader iov_iter
+ *
+ * \retval <0  failure
+ * \retval 0   success
+ * \retval >0  @iocb->ki_pos has passed the EOF
+ */
+static int file_read_confine_iter(struct lu_env *env, struct kiocb *iocb,
+                                 struct iov_iter *to)
+{
+       struct cl_attr *attr = vvp_env_thread_attr(env);
+       struct file *file = iocb->ki_filp;
+       struct inode *inode = file_inode(file);
+       struct ll_inode_info *lli = ll_i2info(inode);
+       loff_t read_end = iocb->ki_pos + iov_iter_count(to);
+       loff_t kms;
+       loff_t size;
+       int rc;
+
+       cl_object_attr_lock(lli->lli_clob);
+       rc = cl_object_attr_get(env, lli->lli_clob, attr);
+       cl_object_attr_unlock(lli->lli_clob);
+       if (rc != 0)
+               return rc;
+
+       kms = attr->cat_kms;
+       /* if read beyond end-of-file, adjust read count */
+       if (kms > 0 && (iocb->ki_pos >= kms || read_end > kms)) {
+               rc = ll_glimpse_size(inode);
+               if (rc != 0)
+                       return rc;
+
+               size = i_size_read(inode);
+               if (iocb->ki_pos >= size || read_end > size) {
+                       CDEBUG(D_VFSTRACE,
+                              "%s: read [%llu, %llu] over eof, kms %llu, file_size %llu.\n",
+                              file_dentry(file)->d_name.name,
+                              iocb->ki_pos, read_end, kms, size);
+
+                       if (iocb->ki_pos >= size)
+                               return 1;
+
+                       if (read_end > size)
+                               iov_iter_truncate(to, size - iocb->ki_pos);
+               }
+       }
+
+       return rc;
+}
+
 /*
  * Read from a file (through the page cache).
  */
@@ -1952,6 +2005,7 @@ static ssize_t ll_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
        __u16 refcheck;
        ktime_t kstart = ktime_get();
        bool cached;
+       bool stale_data = false;
 
        ENTRY;
 
@@ -1963,6 +2017,16 @@ static ssize_t ll_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
        if (!iov_iter_count(to))
                RETURN(0);
 
+       env = cl_env_get(&refcheck);
+       if (IS_ERR(env))
+               RETURN(PTR_ERR(env));
+
+       result = file_read_confine_iter(env, iocb, to);
+       if (result < 0)
+               GOTO(out, result);
+       else if (result > 0)
+               stale_data = true;
+
        /**
         * Currently when PCC read failed, we do not fall back to the
         * normal read path, just return the error.
@@ -1984,10 +2048,6 @@ static ssize_t ll_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
        if (result < 0 || iov_iter_count(to) == 0)
                GOTO(out, result);
 
-       env = cl_env_get(&refcheck);
-       if (IS_ERR(env))
-               RETURN(PTR_ERR(env));
-
        args = ll_env_args(env);
        args->u.normal.via_iter = to;
        args->u.normal.via_iocb = iocb;
@@ -1999,8 +2059,18 @@ static ssize_t ll_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
        else if (result == 0)
                result = rc2;
 
-       cl_env_put(env, &refcheck);
 out:
+       cl_env_put(env, &refcheck);
+
+       if (stale_data && result > 0) {
+               /**
+                * we've reached EOF before the read, the data read are cached
+                * stale data.
+                */
+               iov_iter_truncate(to, 0);
+               result = 0;
+       }
+
        if (result > 0) {
                ll_rw_stats_tally(ll_i2sbi(file_inode(file)), current->pid,
                                  file->private_data, iocb->ki_pos, result,