Back-patch fix that allows AllocateFile() to return errno=ENFILE/EMFILE

after we are no longer able to close any more VFDs.  This is needed to
avoid postmaster crash under out-of-file-descriptors conditions.

diff --git a/src/backend/storage/file/fd.c b/src/backend/storage/file/fd.c
index e3e1ff00e4c53cf5aeba781d36841a4e070b9c95..4db92bc7a9a70984de35f7695830e86adffb5733 100644 (file)
--- a/src/backend/storage/file/fd.c
+++ b/src/backend/storage/file/fd.c
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *   $Header: /cvsroot/pgsql/src/backend/storage/file/fd.c,v 1.56 2000/04/12 17:15:35 momjian Exp $
+ *   $Header: /cvsroot/pgsql/src/backend/storage/file/fd.c,v 1.56.2.1 2000/09/23 23:31:24 tgl Exp $
  *
  * NOTES:
  *
@@ -181,7 +181,7 @@ static void Delete(File file);
 static void LruDelete(File file);
 static void Insert(File file);
 static int LruInsert(File file);
-static void ReleaseLruFile(void);
+static bool ReleaseLruFile(void);
 static File AllocateVfd(void);
 static void FreeVfd(File file);
 
@@ -347,7 +347,10 @@ LruInsert(File file)
    {
 
        while (nfile + numAllocatedFiles >= pg_nofile())
-           ReleaseLruFile();
+       {
+           if (! ReleaseLruFile())
+               break;
+       }
 
        /*
         * The open could still fail for lack of file descriptors, eg due
@@ -358,9 +361,12 @@ tryAgain:
        vfdP->fd = open(vfdP->fileName, vfdP->fileFlags, vfdP->fileMode);
        if (vfdP->fd < 0 && (errno == EMFILE || errno == ENFILE))
        {
+           int     save_errno = errno;
+
            errno = 0;
-           ReleaseLruFile();
-           goto tryAgain;
+           if (ReleaseLruFile())
+               goto tryAgain;
+           errno = save_errno;
        }
 
        if (vfdP->fd < 0)
@@ -392,20 +398,22 @@ tryAgain:
    return 0;
 }
 
-static void
+static bool
 ReleaseLruFile()
 {
    DO_DB(elog(DEBUG, "ReleaseLruFile. Opened %d", nfile));
 
-   if (nfile <= 0)
-       elog(ERROR, "ReleaseLruFile: No open files available to be closed");
-
-   /*
-    * There are opened files and so there should be at least one used vfd
-    * in the ring.
-    */
-   Assert(VfdCache[0].lruMoreRecently != 0);
-   LruDelete(VfdCache[0].lruMoreRecently);
+   if (nfile > 0)
+   {
+       /*
+        * There are opened files and so there should be at least one used
+        * vfd in the ring.
+        */
+       Assert(VfdCache[0].lruMoreRecently != 0);
+       LruDelete(VfdCache[0].lruMoreRecently);
+       return true;            /* freed a file */
+   }
+   return false;               /* no files available to free */
 }
 
 /*
@@ -612,17 +620,23 @@ fileNameOpenFile(FileName fileName,
    vfdP = &VfdCache[file];
 
    while (nfile + numAllocatedFiles >= pg_nofile())
-       ReleaseLruFile();
+   {
+       if (! ReleaseLruFile())
+           break;
+   }
 
 tryAgain:
    vfdP->fd = open(fileName, fileFlags, fileMode);
    if (vfdP->fd < 0 && (errno == EMFILE || errno == ENFILE))
    {
+       int     save_errno = errno;
+
        DO_DB(elog(DEBUG, "fileNameOpenFile: not enough descs, retry, er= %d",
                   errno));
        errno = 0;
-       ReleaseLruFile();
-       goto tryAgain;
+       if (ReleaseLruFile())
+           goto tryAgain;
+       errno = save_errno;
    }
 
    if (vfdP->fd < 0)
@@ -1004,11 +1018,14 @@ TryAgain:
    {
        if (errno == EMFILE || errno == ENFILE)
        {
+           int     save_errno = errno;
+
            DO_DB(elog(DEBUG, "AllocateFile: not enough descs, retry, er= %d",
                       errno));
            errno = 0;
-           ReleaseLruFile();
-           goto TryAgain;
+           if (ReleaseLruFile())
+               goto TryAgain;
+           errno = save_errno;
        }
    }
    else