74 lines
1.9 KiB
C
74 lines
1.9 KiB
C
/*-
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* See the file LICENSE for redistribution information.
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*
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* Copyright (c) 1997,2008 Oracle. All rights reserved.
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*
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* $Id: os_qnx_fsync.c 63573 2008-05-23 21:43:21Z trent.nelson $
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*/
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#include "db_config.h"
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#include "db_int.h"
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/*
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* QNX has special requirements on FSYNC: if the file is a shared memory
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* object, we can not call fsync because it is not implemented, instead,
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* we set the O_DSYNC flag to the file descriptor and then do an empty
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* write so that all data are synced. We only sync this way if the file
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* is a shared memory object, other types of ordinary files are still synced
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* using fsync, to be not only faster but also atomic.
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* We don't just set the O_DSYNC flag on open, since it would force all writes
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* to be sync'ed. And we remove the O_DSYNC if it is not originally set to
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* the file descriptor before passed in to this function.
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* This is slightly different to the VxWorks and hp code above, since QNX does
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* supply a fsync call, it just has a unique requirement.
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*/
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int
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__qnx_fsync(fhp)
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DB_FH *fhp;
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{
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int ret;
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int fd, unset, flags;
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fd = fhp->fd;
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unset = 1;
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ret = flags = 0;
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if (F_ISSET(fhp, DB_FH_REGION))
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{
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RETRY_CHK(fcntl(fd, F_GETFL), ret);
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if (ret == -1)
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goto err;
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/*
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* if already has O_DSYNC flag, we can't remove it
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* after the empty write
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*/
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if (ret & O_DSYNC != 0)
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unset = 0;
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else {
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ret |= O_DSYNC;
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flags = ret;
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RETRY_CHK(fcntl(fd, F_SETFL, flags), ret);
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if (ret == -1)
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goto err;
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}
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/* Do an empty write, to force a sync */
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RETRY_CHK(write(fd, "", 0), ret);
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if (ret == -1)
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goto err;
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/* remove the O_DSYNC flag if necessary */
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if (unset) {
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RETRY_CHK(fcntl(fd, F_GETFL), ret);
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if (ret == -1)
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goto err;
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ret &= ~O_DSYNC;
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flags = ret;
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RETRY_CHK(fcntl(fd, F_SETFL, flags), ret);
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if (ret == -1)
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goto err;
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}
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} else
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RETRY_CHK(fdatasync(fd), ret);
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err: return (ret);
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}
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