Description of problem:
Disk I/O erros in some WAL tests of sqlite build for ppc64le.
Problem also occurs with ppc64.

Version-Release number of selected component (if applicable):
sqlite-3.8.4.2-2.fc21.src.rpm

How reproducible:
Build with make check active.

Actual results:
"Error: disk I/O error" message on some tests.

Additional info:

Trying to build and make checks on the ppc64le arch.
Got some disk I/O errors on the WAL (Write-Ahead Logging) tests.

Reproduced the problem under the sqlite3 command line tool. The disk I/O error seems to occur when the -shm file associated to the database file reaches the 65535 bytes size. Here is the corresponding log:

sqlite> .log stdout
sqlite> vacuum;
(5386) os_unix.c:28099: (22) mmap(/tmp/mydb-shm) - 
(5386) statement aborts at 5: [ATTACH '' AS vacuum_db;] disk I/O error
(10) statement aborts at 2: [vacuum;] disk I/O error
Error: disk I/O error
sqlite>


The strace tool was used to capture some more information:

$ strace sqlite3 mydb 'VACUUM;' 2>&1 | tee mydb-vacuum.strace
...
lseek(5, 53247, SEEK_SET)               = 53247
write(5, "\0", 1)                       = 1
lseek(5, 57343, SEEK_SET)               = 57343
write(5, "\0", 1)                       = 1
lseek(5, 61439, SEEK_SET)               = 61439
write(5, "\0", 1)                       = 1
lseek(5, 65535, SEEK_SET)               = 65535
write(5, "\0", 1)                       = 1
mmap(NULL, 32768, PROT_READ|PROT_WRITE, MAP_SHARED, 5, 0x8000) = -1 EINVAL (Invalid argument)
fcntl(5, F_SETLK, {type=F_UNLCK, whence=SEEK_SET, start=121, len=7}) = 0
fcntl(5, F_SETLK, {type=F_UNLCK, whence=SEEK_SET, start=120, len=1}) = 0
write(2, "Error: disk I/O error\n", 22Error: disk I/O error
) = 22
exit_group(10)                          = ?
+++ exited with 10 +++


Looking at the os_unix.c file, in the unixShmMap() function:
...
    pShmNode->apRegion = apNew;
    while(pShmNode->nRegion<=iRegion){
      void *pMem;
      if( pShmNode->h>=0 ){
        pMem = osMmap(0, szRegion,
            pShmNode->isReadonly ? PROT_READ : PROT_READ|PROT_WRITE,
            MAP_SHARED, pShmNode->h, szRegion*(i64)pShmNode->nRegion
        );
        if( pMem==MAP_FAILED ){
4410      rc = unixLogError(SQLITE_IOERR_SHMMAP, "mmap", pShmNode->zFilename);
          goto shmpage_out;
        }
      }else{
        pMem = sqlite3_malloc(szRegion);
        if( pMem==0 ){
          rc = SQLITE_NOMEM;
          goto shmpage_out;
        }
        memset(pMem, 0, szRegion);
      }
      pShmNode->apRegion[pShmNode->nRegion] = pMem;
      pShmNode->nRegion++;
    }
  }
...

At line 4410, the error message regarding mmap if displayed, and SQLITE_IOERR_SHMMAP symbol value is 5386 (defined in sqlite3.h) as displayed in the sqlite log, with the EINVAL value for errno. The message is displayed because the call to osMmap() failed.


The osMmap() is defined in the same os_unix.c file as:
/*                                                                              
** Many system calls are accessed through pointer-to-functions so that          
** they may be overridden at runtime to facilitate fault injection during       
** testing and sandboxing.  The following array holds the names and pointers    
** to all overrideable system calls.                                            
*/
static struct unix_syscall {
  const char *zName;            /* Name of the system call */
  sqlite3_syscall_ptr pCurrent; /* Current value of the system call */
  sqlite3_syscall_ptr pDefault; /* Default value */
} aSyscall[] = {
...
#if !defined(SQLITE_OMIT_WAL) || SQLITE_MAX_MMAP_SIZE>0
  { "mmap",       (sqlite3_syscall_ptr)mmap,     0 },
#define osMmap ((void*(*)(void*,size_t,int,int,int,off_t))aSyscall[21].pCurrent)
...
}; /* End of the overrideable system calls */


Failing call:
mmap(NULL, 32768, PROT_READ|PROT_WRITE, MAP_SHARED, 5, 0x8000) = -1 EINVAL (Invalid argument)

Looking at the mmap() man page, errno can be set to EINVAL in following three cases:
...
       EINVAL We don't like addr, length, or offset (e.g., they are too large,
              or not aligned on a page boundary).

       EINVAL (since Linux 2.6.12) length was 0.

       EINVAL flags  contained neither MAP_PRIVATE or MAP_SHARED, or contained
              both of these values.
...

The case to consider should probably be the first one.


Note this problem does not seem to be specific to ppc64le since it also occur with a ppc64 build, see:

http://ppc.koji.fedoraproject.org/kojifiles/packages/sqlite/3.8.4/1.fc21/data/logs/ppc64/build.log