sync_file_range man page on CentOS

Man page or keyword search:  
man Server   8420 pages
apropos Keyword Search (all sections)
Output format
CentOS logo
[printable version]

SYNC_FILE_RANGE(2)	   Linux Programmer's Manual	    SYNC_FILE_RANGE(2)

NAME
       sync_file_range - sync a file segment with disk

SYNOPSIS
       #define _GNU_SOURCE
       #include <fcntl.h>

       void sync_file_range(int fd, off64_t offset, off64_t nbytes,
			    unsigned int flags);

DESCRIPTION
       sync_file_range() permits fine control when synchronising the open file
       referred to by the file descriptor fd with disk.

       offset is the starting byte of  the  file  range	 to  be	 synchronised.
       nbytes  specifies the length of the range to be synchronised, in bytes;
       if nbytes is zero, then all bytes from offset through  to  the  end  of
       file  are synchronised.	Synchronisation is in units of the system page
       size: offset is rounded down to a page boundary;	 (offset+nbytes-1)  is
       rounded up to a page boundary.

       The flags bit-mask argument can include any of the following values:

       SYNC_FILE_RANGE_WAIT_BEFORE
	      Wait  upon  write-out  of	 all pages in the specified range that
	      have already been submitted to the device driver	for  write-out
	      before performing any write.

       SYNC_FILE_RANGE_WRITE
	      Initiate	write-out  of  all  dirty pages in the specified range
	      which are not presently submitted write-out.

       SYNC_FILE_RANGE_WAIT_AFTER
	      Wait upon write-out of all pages in the range  after  performing
	      any write.

       Specifying flags as 0 is permitted, as a no-op.

NOTES
       None  of	 these	operations  write out the file's metadata.  Therefore,
       unless the application is strictly performing  overwrites  of  already-
       instantiated disk blocks, there are no guarantees that the data will be
       available after a crash.

       SYNC_FILE_RANGE_WAIT_BEFORE and SYNC_FILE_RANGE_WAIT_AFTER will	detect
       any  I/O errors or ENOSPC conditions and will return these to the call‐
       er.

       Useful combinations of the flags bits are:

       SYNC_FILE_RANGE_WAIT_BEFORE | SYNC_FILE_RANGE_WRITE
	      Ensures that all pages in the specified range which  were	 dirty
	      when  sync_file_range()  was  called are placed under write-out.
	      This is a start-write-for-data-integrity operation.

       SYNC_FILE_RANGE_WRITE
	      Start write-out of all dirty pages in the specified range	 which
	      are  not	presently  under  write-out.   This is an asynchronous
	      flush-to-disk  operation.	  This	is  not	 suitable   for	  data
	      integrity operations.

       SYNC_FILE_RANGE_WAIT_BEFORE (or SYNC_FILE_RANGE_WAIT_AFTER)
	      Wait  for	 completion of write-out of all pages in the specified
	      range.	 This	 can	be    used    after	an     earlier
	      SYNC_FILE_RANGE_WAIT_BEFORE | SYNC_FILE_RANGE_WRITE operation to
	      wait for completion of that operation, and obtain its result.

       SYNC_FILE_RANGE_WAIT_BEFORE	 |	 SYNC_FILE_RANGE_WRITE	     |
       SYNC_FILE_RANGE_WAIT_AFTER
	      This  is	a  traditional fdatasync(2) operation.	It is a write-
	      for-data-integrity operation that will ensure that all pages  in
	      the  specified range which were dirty when sync_file_range() was
	      called are committed to disk.

ERRORS
       EBADF  fd is not a valid file descriptor.

       EIO    I/O error.

       EINVAL flags specifies an invalid bit; or offset or nbytes is invalid.

       ENOMEM Out of memory.

       ENOSPC Out of disk space.

       ESPIPE fd refers to something  other  than  a  regular  file,  a	 block
	      device, a directory, or a symbolic link.

CONFORMING TO
       This  system  call is Linux specific, and should be avoided in portable
       programs.

SEE ALSO
       fdatasync(2), fsync(2), msync(2), sync(2)

Linux 2.6.17			  2006-07-05		    SYNC_FILE_RANGE(2)
[top]

List of man pages available for CentOS

Copyright (c) for man pages and the logo by the respective OS vendor.

For those who want to learn more, the polarhome community provides shell access and support.

[legal] [privacy] [GNU] [policy] [cookies] [netiquette] [sponsors] [FAQ]
Tweet
Polarhome, production since 1999.
Member of Polarhome portal.
Based on Fawad Halim's script.
...................................................................
Vote for polarhome
Free Shell Accounts :: the biggest list on the net