DragonFly On-Line Manual Pages

MSYNC(2)                 DragonFly System Calls Manual                MSYNC(2)

NAME
     msync -- synchronize a mapped region

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <sys/types.h>
     #include <sys/mman.h>

     int
     msync(void *addr, size_t len, int flags);

DESCRIPTION
     The msync() system call writes any modified pages back to the filesystem
     and updates the file modification time.  If len is 0, all modified pages
     within the region containing addr will be flushed; if len is non-zero,
     only those pages containing addr and len-1 succeeding locations will be
     examined.  The flags argument may be specified as follows:

     MS_ASYNC       Return immediately

     MS_SYNC        Perform synchronous writes

     MS_INVALIDATE  Invalidate all cached data

RETURN VALUES
     The msync() function returns the value 0 if successful; otherwise the
     value -1 is returned and the global variable errno is set to indicate the
     error.

ERRORS
     msync() will fail if:

     [EINVAL]           addr is not a multiple of the hardware page size.

     [EINVAL]           len is too large or negative.

     [EINVAL]           flags was both MS_ASYNC and MS_INVALIDATE.  Only one
                        of these flags is allowed.

     [EIO]              An I/O error occurred while writing to the file
                        system.

SEE ALSO
     madvise(2), mincore(2), mprotect(2), munmap(2)

HISTORY
     The msync() function first appeared in 4.4BSD.

DragonFly 4.3                    June 21, 1994                   DragonFly 4.3