From 22b51232c0df7eacfc02b102432d1e8ad8d00f74 Mon Sep 17 00:00:00 2001 From: Volker Lendecke Date: Fri, 7 Sep 2001 15:35:26 +0000 Subject: Fixed paragraph about byte range locking. Jerry, could you make a pdf of this? Thanks, Volker (This used to be commit 3811b6a9eba8c5567b4df01c86cc4fe33b0a8079) --- docs/docbook/projdoc/UNIX_INSTALL.sgml | 35 +++++++++++++++++++--------------- 1 file changed, 20 insertions(+), 15 deletions(-) (limited to 'docs/docbook') diff --git a/docs/docbook/projdoc/UNIX_INSTALL.sgml b/docs/docbook/projdoc/UNIX_INSTALL.sgml index 41eb7a478c..0e4d8a5d03 100644 --- a/docs/docbook/projdoc/UNIX_INSTALL.sgml +++ b/docs/docbook/projdoc/UNIX_INSTALL.sgml @@ -379,21 +379,26 @@ The second is the "deny modes" that are specified when a file is open. - Samba supports "record locking" using the fcntl() unix system - call. This is often implemented using rpc calls to a rpc.lockd process - running on the system that owns the filesystem. Unfortunately many - rpc.lockd implementations are very buggy, particularly when made to - talk to versions from other vendors. It is not uncommon for the - rpc.lockd to crash. - - There is also a problem translating the 32 bit lock - requests generated by PC clients to 31 bit requests supported - by most unixes. Unfortunately many PC applications (typically - OLE2 applications) use byte ranges with the top bit set - as semaphore sets. Samba attempts translation to support - these types of applications, and the translation has proved - to be quite successful. - + Record locking semantics under Unix is very + different from record locking under Windows. Versions + of Samba before 2.2 have tried to use the native + fcntl() unix system call to implement proper record + locking between different Samba clients. This can not + be fully correct due to several reasons. The simplest + is the fact that a Windows client is allowed to lock a + byte range up to 2^32 or 2^64, depending on the client + OS. The unix locking only supports byte ranges up to + 2^31. So it is not possible to correctly satisfy a + lock request above 2^31. There are many more + differences, too many to be listed here. + + Samba 2.2 and above implements record locking + completely independent of the underlying unix + system. If a byte range lock that the client requests + happens to fall into the range 0-2^31, Samba hands + this request down to the Unix system. All other locks + can not be seen by unix anyway. + Strictly a SMB server should check for locks before every read and write call on a file. Unfortunately with the way fcntl() works this can be slow and may overstress the -- cgit