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2008-04-21dlm: move plock code from gfs2David Teigland
Move the code that handles cluster posix locks from gfs2 into the dlm so that it can be used by both gfs2 and ocfs2. Signed-off-by: David Teigland <teigland@redhat.com>
2008-01-29dlm: proper prototypesAdrian Bunk
This patch adds a proper prototype for some functions in fs/dlm/dlm_internal.h Signed-off-by: Adrian Bunk <bunk@kernel.org> Signed-off-by: David Teigland <teigland@redhat.com>
2007-07-09[DLM] add lock timeouts and warnings [2/6]David Teigland
New features: lock timeouts and time warnings. If the DLM_LKF_TIMEOUT flag is set, then the request/conversion will be canceled after waiting the specified number of centiseconds (specified per lock). This feature is only available for locks requested through libdlm (can be enabled for kernel dlm users if there's a use for it.) If the new DLM_LSFL_TIMEWARN flag is set when creating the lockspace, then a warning message will be sent to userspace (using genetlink) after a request/conversion has been waiting for a given number of centiseconds (configurable per node). The time warnings will be used in the future to do deadlock detection in userspace. Signed-off-by: David Teigland <teigland@redhat.com> Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
2006-12-07[DLM] Clean up lowcommsPatrick Caulfield
This fixes up most of the things pointed out by akpm and Pavel Machek with comments below indicating why some things have been left: Andrew Morton wrote: > >> +static struct nodeinfo *nodeid2nodeinfo(int nodeid, gfp_t alloc) >> +{ >> + struct nodeinfo *ni; >> + int r; >> + int n; >> + >> + down_read(&nodeinfo_lock); > > Given that this function can sleep, I wonder if `alloc' is useful. > > I see lots of callers passing in a literal "0" for `alloc'. That's in fact > a secret (GFP_ATOMIC & ~__GFP_HIGH). I doubt if that's what you really > meant. Particularly as the code could at least have used __GFP_WAIT (aka > GFP_NOIO) which is much, much more reliable than "0". In fact "0" is the > least reliable mode possible. > > IOW, this is all bollixed up. When 0 is passed into nodeid2nodeinfo the function does not try to allocate a new structure at all. it's an indication that the caller only wants the nodeinfo struct for that nodeid if there actually is one in existance. I've tidied the function itself so it's more obvious, (and tidier!) >> +/* Data received from remote end */ >> +static int receive_from_sock(void) >> +{ >> + int ret = 0; >> + struct msghdr msg; >> + struct kvec iov[2]; >> + unsigned len; >> + int r; >> + struct sctp_sndrcvinfo *sinfo; >> + struct cmsghdr *cmsg; >> + struct nodeinfo *ni; >> + >> + /* These two are marginally too big for stack allocation, but this >> + * function is (currently) only called by dlm_recvd so static should be >> + * OK. >> + */ >> + static struct sockaddr_storage msgname; >> + static char incmsg[CMSG_SPACE(sizeof(struct sctp_sndrcvinfo))]; > > whoa. This is globally singly-threaded code?? Yes. it is only ever run in the context of dlm_recvd. >> >> +static void initiate_association(int nodeid) >> +{ >> + struct sockaddr_storage rem_addr; >> + static char outcmsg[CMSG_SPACE(sizeof(struct sctp_sndrcvinfo))]; > > Another static buffer to worry about. Globally singly-threaded code? Yes. Only ever called by dlm_sendd. >> + >> +/* Send a message */ >> +static int send_to_sock(struct nodeinfo *ni) >> +{ >> + int ret = 0; >> + struct writequeue_entry *e; >> + int len, offset; >> + struct msghdr outmsg; >> + static char outcmsg[CMSG_SPACE(sizeof(struct sctp_sndrcvinfo))]; > > Singly-threaded? Yep. >> >> +static void dealloc_nodeinfo(void) >> +{ >> + int i; >> + >> + for (i=1; i<=max_nodeid; i++) { >> + struct nodeinfo *ni = nodeid2nodeinfo(i, 0); >> + if (ni) { >> + idr_remove(&nodeinfo_idr, i); > > Didn't that need locking? Not. it's only ever called at DLM shutdown after all the other threads have been stopped. >> >> +static int write_list_empty(void) >> +{ >> + int status; >> + >> + spin_lock_bh(&write_nodes_lock); >> + status = list_empty(&write_nodes); >> + spin_unlock_bh(&write_nodes_lock); >> + >> + return status; >> +} > > This function's return value is meaningless. As soon as the lock gets > dropped, the return value can get out of sync with reality. > > Looking at the caller, this _might_ happen to be OK, but it's a nasty and > dangerous thing. Really the locking should be moved into the caller. It's just an optimisation to allow the caller to schedule if there is no work to do. if something arrives immediately afterwards then it will get picked up when the process re-awakes (and it will be woken by that arrival). The 'accepting' atomic has gone completely. as Andrew pointed out it didn't really achieve much anyway. I suspect it was a plaster over some other startup or shutdown bug to be honest. Signed-off-by: Patrick Caulfield <pcaulfie@redhat.com> Signed-off-by: Steven Whitehouse <swhiteho@redhat.com> Cc: Andrew Morton <akpm@osdl.org> Cc: Pavel Machek <pavel@ucw.cz>
2006-07-13[DLM] dlm: user locksDavid Teigland
This changes the way the dlm handles user locks. The core dlm is now aware of user locks so they can be dealt with more efficiently. There is no more dlm_device module which previously managed its own duplicate copy of every user lock. Signed-off-by: Patrick Caulfield <pcaulfie@redhat.com> Signed-off-by: David Teigland <teigland@redhat.com> Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
2006-01-18[DLM] The core of the DLM for GFS2/CLVMDavid Teigland
This is the core of the distributed lock manager which is required to use GFS2 as a cluster filesystem. It is also used by CLVM and can be used as a standalone lock manager independantly of either of these two projects. It implements VAX-style locking modes. Signed-off-by: David Teigland <teigland@redhat.com> Signed-off-by: Steve Whitehouse <swhiteho@redhat.com>