LU-16468 llite: protect layout before read IO going

It's possible that the before the read IO, file_read_confine_iter()
->lov_attr_get() to get proper kms (known minimum size of the file),
and lov_attr_get() presumes that it's called under ongoing IO, which
protected the layout from changing, while it's not in this case.

Signed-off-by: Bobi Jam <bobijam@whamcloud.com>
Change-Id: I1b36ec6e158331e63e8026ee2b986d5a7e3cb6dc
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/49622
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Mikhail Pershin <mpershin@whamcloud.com>
Reviewed-by: Yang Sheng <ys@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>

diff --git a/lustre/llite/file.c b/lustre/llite/file.c
index d33f115..f7b852a 100644 (file)
--- a/lustre/llite/file.c
+++ b/lustre/llite/file.c
@@ -2038,20 +2038,36 @@ ll_do_fast_read(struct kiocb *iocb, struct iov_iter *iter)
 static int file_read_confine_iter(struct lu_env *env, struct kiocb *iocb,
                                  struct iov_iter *to)
 {
+       struct cl_io *io;
        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);
+       struct cl_object *obj = lli->lli_clob;
        loff_t read_end = iocb->ki_pos + iov_iter_count(to);
        loff_t kms;
        loff_t size;
-       int rc;
+       int rc = 0;
+
+       ENTRY;
+
+       if (!obj)
+               RETURN(rc);
+
+       io = vvp_env_thread_io(env);
+       io->ci_obj = obj;
+       rc = cl_io_init(env, io, CIT_MISC, obj);
+       if (rc < 0)
+               GOTO(fini_io, 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;
+
+fini_io:
+       cl_io_fini(env, io);
+       if (rc < 0)
+               RETURN(rc);
 
        kms = attr->cat_kms;
        /* if read beyond end-of-file, adjust read count */
@@ -2068,14 +2084,14 @@ static int file_read_confine_iter(struct lu_env *env, struct kiocb *iocb,
                               iocb->ki_pos, read_end, kms, size);
 
                        if (iocb->ki_pos >= size)
-                               return 1;
+                               RETURN(1);
 
                        if (read_end > size)
                                iov_iter_truncate(to, size - iocb->ki_pos);
                }
        }
 
-       return rc;
+       RETURN(rc);
 }
 
 /*