Add all extant virtual files to a list. Add an "exclusive owner" (`exc_owner`)

member to all virtual files.  Add a routine, H5FD_has_conflict(), that returns
true if a new virtual file is identical to an existing virtual file that has an
exclusive owner.  Establish an exclusive owner for a VFD SWMR virtual file's
lower virtual file.

Rename bsdqueue.h to H5queue.h and install it, since it's used by H5FDpublic.h.

This is part of a changeset that helps us avoid creating multiple H5F_shared_t
for one file when virtual datasets are used with VFD SWMR.  The old code for
deduplicating VFD SWMR H5F_shared_t instances did not work correctly with VFD
SWMR, so we'd end up with multiple H5F_shared_t all active on the same file.

11 files changed, 60 insertions, 12 deletions

diff --git a/src/H5FD.c b/src/H5FD.c
index bd26bd9..e136e12 100644
--- a/src/H5FD.c
+++ b/src/H5FD.c
@@ -92,6 +92,8 @@ hbool_t H5_PKG_INIT_VAR = FALSE;
  */
 static unsigned long H5FD_file_serial_no_g;
 
+static TAILQ_HEAD(_all_vfds, H5FD_t) all_vfds = TAILQ_HEAD_INITIALIZER(all_vfds);
+
 /* File driver ID class */
 static const H5I_class_t H5I_VFL_CLS[1] = {{
     H5I_VFL,                    /* ID class value */
@@ -677,6 +679,24 @@ done:
     FUNC_LEAVE_API(ret_value)
 }
 
+/* Return `true` if a second H5FD_t identical to `file`
+ * has an exclusive owner, `false` otherwise.
+ */
+bool
+H5FD_has_conflict(H5FD_t *file)
+{
+    H5FD_t *item;
+
+    TAILQ_FOREACH(item, &all_vfds, link) {
+        // skip "self", skip unowned
+        if (item == file || item->exc_owner == NULL)
+            continue;
+        if (H5FDcmp(file, item) == 0)
+            return true;
+    }
+    return false;
+}
+
 
 /*-------------------------------------------------------------------------
  * Function:    H5FD_open
@@ -743,6 +763,8 @@ H5FD_open(const char *name, unsigned flags, hid_t fapl_id, haddr_t maxaddr)
     if(NULL == (file = (driver->open)(name, flags, fapl_id, maxaddr)))
         HGOTO_ERROR(H5E_VFL, H5E_CANTINIT, NULL, "open failed")
 
+    file->exc_owner = NULL;
+
     /* Set the file access flags */
     file->access_flags = flags;
 
@@ -774,10 +796,13 @@ H5FD_open(const char *name, unsigned flags, hid_t fapl_id, haddr_t maxaddr)
     /* (This will be changed later, when the superblock is located) */
     file->base_addr = 0;
 
+    TAILQ_INSERT_TAIL(&all_vfds, file, link);
+
     /* Set return value */
     ret_value = file;
 
 done:
+    /* XXX We leak H5FD_t's on many error conditions. */
     /* Can't cleanup 'file' information, since we don't know what type it is */
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5FD_open() */
@@ -832,6 +857,7 @@ herr_t
 H5FD_close(H5FD_t *file)
 {
     const H5FD_class_t *driver;
+    H5FD_t *item;
     herr_t              ret_value = SUCCEED;
 
     FUNC_ENTER_NOAPI(FAIL)
@@ -845,6 +871,12 @@ H5FD_close(H5FD_t *file)
     if(H5I_dec_ref(file->driver_id) < 0)
         HGOTO_ERROR(H5E_VFL, H5E_CANTDEC, FAIL, "can't close driver ID")
 
+    TAILQ_FOREACH(item, &all_vfds, link) {
+        if (item->exc_owner == file)
+            item->exc_owner = NULL;
+    }
+    TAILQ_REMOVE(&all_vfds, file, link);
+
     /* Dispatch to the driver for actual close. If the driver fails to
      * close the file then the file will be in an unusable state.
      */
diff --git a/src/H5FDprivate.h b/src/H5FDprivate.h
index 9126371..4eeea36 100644
--- a/src/H5FDprivate.h
+++ b/src/H5FDprivate.h
@@ -317,6 +317,7 @@ H5_DLL herr_t H5FD_free_driver_info(hid_t driver_id, const void *driver_info);
 H5_DLL hid_t H5FD_register(const void *cls, size_t size, hbool_t app_ref);
 H5_DLL H5FD_t *H5FD_open(const char *name, unsigned flags, hid_t fapl_id,
 		  haddr_t maxaddr);
+bool H5FD_has_conflict(H5FD_t *);
 H5_DLL herr_t H5FD_close(H5FD_t *file);
 H5_DLL int H5FD_cmp(const H5FD_t *f1, const H5FD_t *f2);
 H5_DLL herr_t H5FD_driver_query(const H5FD_class_t *driver, unsigned long *flags/*out*/);
diff --git a/src/H5FDpublic.h b/src/H5FDpublic.h
index 61bf212..ab8a868 100644
--- a/src/H5FDpublic.h
+++ b/src/H5FDpublic.h
@@ -18,6 +18,7 @@
 #ifndef _H5FDpublic_H
 #define _H5FDpublic_H
 
+#include "H5queue.h"
 #include "H5public.h"
 #include "H5Fpublic.h"		/*for H5F_close_degree_t */
 
@@ -319,6 +320,11 @@ typedef struct H5FD_free_t {
 struct H5FD_t {
     hid_t               driver_id;      /*driver ID for this file   */
     const H5FD_class_t *cls;            /*constant class info       */
+
+    TAILQ_ENTRY(H5FD_t) link;           /* Linkage for list of all VFs. */
+    H5FD_t *exc_owner;                  /* Pointer to an exclusive owner
+                                         * or NULL if none.
+                                         */
     unsigned long       fileno;         /* File 'serial' number     */
     unsigned            access_flags;   /* File access flags (from create or open) */
     unsigned long       feature_flags;  /* VFL Driver feature Flags */
diff --git a/src/H5FDvfd_swmr.c b/src/H5FDvfd_swmr.c
index 72906ff..af633e3 100644
--- a/src/H5FDvfd_swmr.c
+++ b/src/H5FDvfd_swmr.c
@@ -351,6 +351,8 @@ H5FD_vfd_swmr_open(const char *name, unsigned flags, hid_t fapl_id,
                                        maxaddr)) == NULL)
         HGOTO_ERROR(H5E_VFL, H5E_CANTOPENFILE, NULL, "can't set driver info");
 
+    file->hdf5_file_lf->exc_owner = &file->pub;
+
     /* set pb_configured to FALSE.  This field should not exist, but 
      * until we modify the file open procedure to create the page buffer
      * before there is any file I/O when opening a file VFD SWMR reader, 
diff --git a/src/H5FDvfd_swmr_private.h b/src/H5FDvfd_swmr_private.h
index 94fe662..c6f5a97 100644
--- a/src/H5FDvfd_swmr_private.h
+++ b/src/H5FDvfd_swmr_private.h
@@ -12,7 +12,7 @@
 #ifndef _H5FDvfd_swmr_private_H
 #define _H5FDvfd_swmr_private_H
 
-#include "bsdqueue.h"   /* for TAILQ_* */
+#include "H5queue.h"   /* for TAILQ_* */
 #include "hlog.h"   /* for TAILQ_* */
 
 /* Forward declaration */
diff --git a/src/H5Fint.c b/src/H5Fint.c
index d76f2b1..84fb1d1 100644
--- a/src/H5Fint.c
+++ b/src/H5Fint.c
@@ -1572,7 +1572,6 @@ H5F_open(const char *name, unsigned flags, hid_t fcpl_id, hid_t fapl_id)
     hbool_t             ci_load = FALSE;    /* whether MDC ci load requested */
     hbool_t             ci_write = FALSE;   /* whether MDC CI write requested */
     hbool_t             file_create = FALSE;    /* creating a new file or not */
-    H5FD_t             *underlying_lf = NULL;   /* underlying file driver for VFD SWMR */
     H5F_vfd_swmr_config_t *vfd_swmr_config_ptr = NULL;  /* Points to VFD SMWR config info */
     H5F_t              *ret_value = NULL;       /*actual return value           */
 
@@ -1645,14 +1644,20 @@ H5F_open(const char *name, unsigned flags, hid_t fcpl_id, hid_t fapl_id)
             HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, NULL, "unable to open file: name = '%s', tent_flags = %x", name, tent_flags)
     } /* end if */
 
-    /* For VFD SWMR driver, retrieve the underlying vfd for the search in H5F__sfile_search() */
-    if(H5FD_is_vfd_swmr_driver(lf))
-        underlying_lf = H5FD_vfd_swmr_get_underlying_vfd(lf);
-    else
-        underlying_lf = lf;
+    /* Do not reuse a virtual file opened exclusively by a second virtual
+     * file.
+     */
+    if (H5FD_has_conflict(lf)) {
+        if(H5FD_close(lf) < 0) {
+            HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, NULL,
+                "file '%s' already open exclusively; could not close", name);
+        }
+        HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, NULL,
+            "file '%s' already open exclusively", name);
+    }
 
     /* Is the file already open? */
-    if((shared = H5F__sfile_search(underlying_lf)) != NULL) {
+    if((shared = H5F__sfile_search(lf)) != NULL) {
         /*
          * The file is already open, so use that one instead of the one we
          * just opened. We only one one H5FD_t* per file so one doesn't
diff --git a/src/H5Fpkg.h b/src/H5Fpkg.h
index 45ff0ee..1136cb4 100644
--- a/src/H5Fpkg.h
+++ b/src/H5Fpkg.h
@@ -27,7 +27,7 @@
 #define _H5Fpkg_H
 
 /* BSD queue macros */
-#include "bsdqueue.h"
+#include "H5queue.h"
 
 /* Get package's private header */
 #include "H5Fprivate.h"
diff --git a/src/H5MF.c b/src/H5MF.c
index c320f2c..dbaf17c 100644
--- a/src/H5MF.c
+++ b/src/H5MF.c
@@ -22,7 +22,7 @@
  *-------------------------------------------------------------------------
  */
 
-#include "bsdqueue.h"
+#include "H5queue.h"
 #include "hlog.h"
 
 /****************/
diff --git a/src/bsdqueue.h b/src/H5queue.h
index 816acca..816acca 100644
--- a/src/bsdqueue.h
+++ b/src/H5queue.h
diff --git a/src/Makefile.am b/src/Makefile.am
index d917c3e..cb3fa3c 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -139,7 +139,9 @@ if ROS3_VFD_CONDITIONAL
 endif
 
 # Public headers
-include_HEADERS = hdf5.h H5api_adpt.h H5overflow.h H5pubconf.h H5public.h H5version.h \
+include_HEADERS = hdf5.h H5api_adpt.h H5overflow.h H5pubconf.h H5public.h \
+	H5queue.h \
+	H5version.h \
         H5Apublic.h H5ACpublic.h \
         H5Cpublic.h H5Dpublic.h \
         H5Epubgen.h H5Epublic.h H5ESpublic.h H5Fpublic.h \
diff --git a/src/hlog.h b/src/hlog.h
index 95e8055..2489a47 100644
--- a/src/hlog.h
+++ b/src/hlog.h
@@ -17,7 +17,7 @@
 #include <syslog.h>
 #include <sys/cdefs.h>
 
-#include "bsdqueue.h"
+#include "H5queue.h"
 
 #ifndef _unused
 #define _unused __attribute__((unused))