/**
* write an existing volume disk header.
*
* @param[in] hdr volume disk header
* @param[in] dp disk partition object
* @param[in] cr assert if O_CREAT | O_EXCL should be passed to open()
*
* @return operation status
* @retval 0 success
* @retval -1 volume header doesn't exist
* @retval EIO failed to write volume header
*
* @internal
*/
static afs_int32
_VWriteVolumeDiskHeader(VolumeDiskHeader_t * hdr,
struct DiskPartition64 * dp,
int flags)
{
afs_int32 code = 0;
int fd;
char path[MAXPATHLEN];
#ifdef AFS_DEMAND_ATTACH_FS
/* prevent racing with VGC scanners reading the vol header while we are
* writing it */
code = VPartHeaderLock(dp, READ_LOCK);
if (code) {
return EIO;
}
#endif /* AFS_DEMAND_ATTACH_FS */
flags |= O_RDWR;
(void)afs_snprintf(path, sizeof(path),
"%s/" VFORMAT,
VPartitionPath(dp), afs_printable_uint32_lu(hdr->id));
fd = open(path, flags, 0644);
if (fd < 0) {
code = errno;
Log("_VWriteVolumeDiskHeader: Couldn't open header for volume %lu, "
"error = %d\n", afs_printable_uint32_lu(hdr->id), errno);
} else if (write(fd, hdr, sizeof(*hdr)) != sizeof(*hdr)) {
Log("_VWriteVolumeDiskHeader: Couldn't write header for volume %lu, "
"error = %d\n", afs_printable_uint32_lu(hdr->id), errno);
code = EIO;
}
if (fd >= 0) {
if (close(fd) != 0) {
Log("_VWriteVolumeDiskHeader: Error closing header for volume "
"%lu, errno %d\n", afs_printable_uint32_lu(hdr->id), errno);
}
}
#ifdef AFS_DEMAND_ATTACH_FS
VPartHeaderUnlock(dp, READ_LOCK);
#endif /* AFS_DEMAND_ATTACH_FS */
return code;
}
/**
* handle a single vol header as part of VWalkVolumeHeaders.
*
* @param[in] dp disk partition
* @param[in] volfunc function to call when a vol header is successfully read
* @param[in] name full path name to the .vol header
* @param[out] hdr header data read in from the .vol header
* @param[in] locked 1 if the partition headers are locked, 0 otherwise
* @param[in] rock the rock to pass to volfunc
*
* @return operation status
* @retval 0 success
* @retval -1 fatal error, stop scanning
* @retval 1 failed to read header
* @retval 2 volfunc callback indicated error after header read
*/
static int
_VHandleVolumeHeader(struct DiskPartition64 *dp, VWalkVolFunc volfunc,
const char *name, struct VolumeDiskHeader *hdr,
int locked, void *rock)
{
int error = 0;
FD_t fd;
if ((fd = OS_OPEN(name, O_RDONLY, 0)) == INVALID_FD
|| OS_READ(fd, hdr, sizeof(*hdr))
!= sizeof(*hdr)
|| hdr->stamp.magic != VOLUMEHEADERMAGIC) {
error = 1;
}
if (fd != INVALID_FD) {
OS_CLOSE(fd);
}
#ifdef AFSFS_DEMAND_ATTACH_FS
if (locked) {
VPartHeaderUnlock(dp);
}
#endif /* AFS_DEMAND_ATTACH_FS */
if (!error && volfunc) {
/* the volume header seems fine; call the caller-supplied
* 'we-found-a-volume-header' function */
int last = 1;
#ifdef AFS_DEMAND_ATTACH_FS
if (!locked) {
last = 0;
}
#endif /* AFS_DEMAND_ATTACH_FS */
error = (*volfunc) (dp, name, hdr, last, rock);
if (error < 0) {
return -1;
}
if (error) {
error = 2;
}
}
#ifdef AFS_DEMAND_ATTACH_FS
if (error && !locked) {
int code;
/* retry reading the volume header under the partition
* header lock, just to be safe and ensure we're not
* racing something rewriting the vol header */
code = VPartHeaderLock(dp, WRITE_LOCK);
if (code) {
Log("Error acquiring partition write lock when "
"looking at header %s\n", name);
return -1;
}
return _VHandleVolumeHeader(dp, volfunc, name, hdr, 1, rock);
}
#endif /* AFS_DEMAND_ATTACH_FS */
return error;
}
