From: Tom Zanussi <zanussi@us.ibm.com> Signed-off-by: Tom Zanussi <zanussi@us.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> --- Documentation/filesystems/relayfs.txt | 17 +++++++++++------ 1 files changed, 11 insertions(+), 6 deletions(-) diff -puN Documentation/filesystems/relayfs.txt~relayfs-update-documentation-fix Documentation/filesystems/relayfs.txt --- 25/Documentation/filesystems/relayfs.txt~relayfs-update-documentation-fix Mon Aug 29 15:25:41 2005 +++ 25-akpm/Documentation/filesystems/relayfs.txt Mon Aug 29 15:25:41 2005 @@ -82,10 +82,15 @@ mmap() results in channel buffer being memory space. Note that you can't do a partial mmap - you must map the entire file, which is NRBUF * SUBBUFSIZE. -read() read the contents of a channel buffer. If there are active - channel writers, results may be unpredictable - users should - make sure that all logging to the channel has ended before - using read(). +read() read the contents of a channel buffer. The bytes read are + 'consumed' by the reader i.e. they won't be available again + to subsequent reads. If the channel is being used in + no-overwrite mode (the default), it can be read at any time + even if there's an active kernel writer. If the channel is + being used in overwrite mode and there are active channel + writers, results may be unpredictable - users should make + sure that all logging to the channel has ended before using + read() with overwrite mode. poll() POLLIN/POLLRDNORM/POLLERR supported. User applications are notified when sub-buffer boundaries are crossed. @@ -256,8 +261,8 @@ consulted. The default subbuf_start() implementation, used if the client doesn't define any callbacks, or doesn't define the subbuf_start() callback, -implements the simplest possible 'overwrite' mode i.e. it does nothing -but return 1. +implements the simplest possible 'no-overwrite' mode i.e. it does +nothing but return 0. Header information can be reserved at the beginning of each sub-buffer by calling the subbuf_start_reserve() helper function from within the _