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 sys- tem.

SEE ALSO

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

HISTORY

The msync() function first appeared in 4.4BSD. DragonFly 3.7 June 21, 1994 DragonFly 3.7