Adds fix for H5Fstart_swmr_write lock issue

Needs a final review pass.

2 files changed, 16 insertions, 4 deletions

diff --git a/src/H5Fint.c b/src/H5Fint.c
index 29bbd45..38bff57 100644
--- a/src/H5Fint.c
+++ b/src/H5Fint.c
@@ -1730,6 +1730,9 @@ H5F_open(const char *name, unsigned flags, hid_t fcpl_id, hid_t fapl_id)
             set_flag = TRUE;
     } /* end else */
 
+    /* Set the file locking flag */
+    file->use_file_locking = use_file_locking;
+
     /* Check to see if both SWMR and cache image are requested.  Fail if so */
     if(H5C_cache_image_status(file, &ci_load, &ci_write) < 0)
         HGOTO_ERROR(H5E_FILE, H5E_CANTGET, NULL, "can't get MDC cache image status")
@@ -3420,6 +3423,7 @@ H5F__start_swmr_write(H5F_t *f)
     H5G_name_t *obj_paths = NULL;   /* Group hierarchy path */
     size_t u;                       /* Local index variable */
     hbool_t setup = FALSE;          /* Boolean flag to indicate whether SWMR setting is enabled */
+    hbool_t use_file_locking = TRUE;/* Using file locks? */
     herr_t ret_value = SUCCEED;     /* Return value */
 
     FUNC_ENTER_PACKAGE
@@ -3531,6 +3535,12 @@ H5F__start_swmr_write(H5F_t *f)
 
     setup = TRUE;
 
+    /* Place an advisory lock on the file */
+    if(f->use_file_locking)
+        if(H5FD_lock(f->shared->lf, TRUE) < 0) {
+            HGOTO_ERROR(H5E_FILE, H5E_CANTLOCKFILE, FAIL, "unable to lock the file")
+        }
+
     /* Mark superblock as dirty */
     if(H5F_super_dirty(f) < 0)
         HGOTO_ERROR(H5E_FILE, H5E_CANTMARKDIRTY, FAIL, "unable to mark superblock as dirty")
@@ -3548,10 +3558,6 @@ H5F__start_swmr_write(H5F_t *f)
         if(H5O_refresh_metadata_reopen(obj_ids[u], &obj_glocs[u], TRUE) < 0)
             HGOTO_ERROR(H5E_ATOM, H5E_CLOSEERROR, FAIL, "can't refresh-close object")
 
-    /* Unlock the file */
-    if(H5FD_unlock(f->shared->lf) < 0)
-        HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, FAIL, "unable to unlock the file")
-
 done:
     if(ret_value < 0 && setup) {
 
@@ -3580,6 +3586,11 @@ done:
             HDONE_ERROR(H5E_FILE, H5E_CANTFLUSH, FAIL, "unable to flush superblock")
     } /* end if */
 
+    /* Unlock the file */
+    if(f->use_file_locking)
+        if(H5FD_unlock(f->shared->lf) < 0)
+            HDONE_ERROR(H5E_FILE, H5E_CANTUNLOCKFILE, FAIL, "unable to unlock the file")
+
     /* Free memory */
     if(obj_ids)
         H5MM_xfree(obj_ids);
diff --git a/src/H5Fpkg.h b/src/H5Fpkg.h
index 14c00e1..7122d36 100644
--- a/src/H5Fpkg.h
+++ b/src/H5Fpkg.h
@@ -373,6 +373,7 @@ struct H5F_t {
     hbool_t             closing;        /* File is in the process of being closed                       */
     struct H5F_t       *parent;         /* Parent file that this file is mounted to                     */
     unsigned            nmounts;        /* Number of children mounted to this file                      */
+    hbool_t             use_file_locking; /* Whether or not to use file locking */
 #ifdef H5_HAVE_PARALLEL
     H5P_coll_md_read_flag_t coll_md_read;  /* Do all metadata reads collectively */
     hbool_t             coll_md_write;  /* Do all metadata writes collectively */