When running a checkpoint while in locking_mode=EXCLUSIVE, be sure to move

the wal-index lock to UNLOCK from READ prior to promoting to CHECKPOINT.

FossilOrigin-Name: be114bdf9bb98c7287f8cb54340c630b0c412e9d

manifest

@@ -1,8 +1,8 @@
 -----BEGIN PGP SIGNED MESSAGE-----
 Hash: SHA1
 
-C Change\sthe\sxShmOpen()\smethod\sof\sthe\sVFS\sto\stake\sthe\sdatabase\sfile\sname\sas\nits\sargument,\snot\sthe\sWAL\sfile\sname.\s\sAlso\sfix\ssome\sunrelated\scompiler\nwarnings.
-D 2010-05-07T20:02:24
+C When\srunning\sa\scheckpoint\swhile\sin\slocking_mode=EXCLUSIVE,\sbe\ssure\sto\smove\nthe\swal-index\slock\sto\sUNLOCK\sfrom\sREAD\sprior\sto\spromoting\sto\sCHECKPOINT.
+D 2010-05-07T20:34:17
 F Makefile.arm-wince-mingw32ce-gcc fcd5e9cd67fe88836360bb4f9ef4cb7f8e2fb5a0
 F Makefile.in a5cad1f8f3e021356bfcc6c77dc16f6f1952bbc3
 F Makefile.linux-gcc d53183f4aa6a9192d249731c90dbdffbd2c68654
@@ -227,7 +227,7 @@ F src/vdbeblob.c 5327132a42a91e8b7acfb60b9d2c3b1c5c863e0e
 F src/vdbemem.c 2a82f455f6ca6f78b59fb312f96054c04ae0ead1
 F src/vdbetrace.c 864cef96919323482ebd9986f2132435115e9cc2
 F src/vtab.c a0f8a40274e4261696ef57aa806de2776ab72cda
-F src/wal.c 6704aa53295073e590f3d802acec9722df671cd8
+F src/wal.c 66147e8b8623050a970ac9ba64688b95eb4e3bc3
 F src/wal.h b4c42014b5fa3b4e6244ac8c65de7ff67adeb27c
 F src/walker.c 3112bb3afe1d85dc52317cb1d752055e9a781f8f
 F src/where.c 75fee9e255b62f773fcadd1d1f25b6f63ac7a356
@@ -816,14 +816,14 @@ F tool/speedtest2.tcl ee2149167303ba8e95af97873c575c3e0fab58ff
 F tool/speedtest8.c 2902c46588c40b55661e471d7a86e4dd71a18224
 F tool/speedtest8inst1.c 293327bc76823f473684d589a8160bde1f52c14e
 F tool/vdbe-compress.tcl d70ea6d8a19e3571d7ab8c9b75cba86d1173ff0f
-P e1230782a371f09cd46dacc8ecbc6a0c5baab2d5
-R 34103b151852b68b8447281dee8b52f5
+P a65c2939267ef6acec4e355a207f98f217e263d6
+R a46357f982ebdd4520842ec1c873b4c4
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-Z 09fd161899845c827ac24875d31a8565
+Z 46431e902a37a907f9e07e8180abbf8b
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manifest.uuid

@@ -1 +1 @@
-a65c2939267ef6acec4e355a207f98f217e263d6
+be114bdf9bb98c7287f8cb54340c630b0c412e9d

src/wal.c

@@ -1349,10 +1349,15 @@ int sqlite3WalCheckpoint(
   int rc;                         /* Return code */
   int isChanged = 0;              /* True if a new wal-index header is loaded */
 
-  assert( pWal->lockState==SQLITE_SHM_UNLOCK );
   assert( pWal->pWiData==0 );
 
   /* Get the CHECKPOINT lock */
+  if( pWal->lockState!=SQLITE_SHM_UNLOCK ){
+    /* This can occur when locking_mode=EXCLUSIVE */
+    assert( pWal->lockState==SQLITE_SHM_READ
+         || pWal->lockState==SQLITE_SHM_READ_FULL );
+    walSetLock(pWal, SQLITE_SHM_UNLOCK);
+  }
   do {
     rc = walSetLock(pWal, SQLITE_SHM_CHECKPOINT);
   }while( rc==SQLITE_BUSY && xBusyHandler(pBusyHandlerArg) );