From 5604b35a61e22930873ffc4e9971002f578e7978 Mon Sep 17 00:00:00 2001 From: Sean Finney Date: Tue, 19 Apr 2011 11:04:35 -0400 Subject: nfs-utils: Increase the stdio file buffer size for procfs files Previously, when writing to /proc/net/rpc/*/channel, if a cache line were larger than the default buffer size (likely 1024 bytes), mountd and svcgssd would split writes into a number of buffer-sized writes. Each of these writes would get an EINVAL error back from the kernel procfs handle (it expects line-oriented input and does not account for multiple/split writes), and no cache update would occur. When such behavior occurs, NFS clients depending on mountd to finish the cache operation would block/hang, or receive EPERM, depending on the context of the operation. This is likely to happen if a user is a member of a large (~100-200) number of groups. Instead, every fopen() on the procfs files in question is followed by a call to setvbuf(), using a per-file dedicated buffer of RPC_CHAN_BUF_SIZE length. Really, mountd should not be using stdio-style buffered file operations on files in /proc to begin with. A better solution would be to use internally managed buffers and calls to write() instead of these stdio calls, but that would be a more extensive change; so this is proposed as a quick and not-so-dirty fix in the meantime. Signed-off-by: Sean Finney Signed-off-by: Steve Dickson --- support/include/misc.h | 3 +++ 1 file changed, 3 insertions(+) (limited to 'support/include/misc.h') diff --git a/support/include/misc.h b/support/include/misc.h index bc5ba23..eedc1fe 100644 --- a/support/include/misc.h +++ b/support/include/misc.h @@ -17,4 +17,7 @@ int weakrandomkey(unsigned char *keyout, int len); extern int is_mountpoint(char *path); +/* size of the file pointer buffers for rpc procfs files */ +#define RPC_CHAN_BUF_SIZE 32768 + #endif /* MISC_H */ -- cgit